Advertisement

Chimeric galectin-3 and collagens: Biomarkers and potential therapeutic targets in fibroproliferative diseases

Open AccessPublished:October 19, 2022DOI:https://doi.org/10.1016/j.jbc.2022.102622
      Fibrosis, stiffening and scarring of an organ/tissue due to genetic abnormalities, environmental factors, infection, and/or injury, is responsible for > 40% of all deaths in the industrialized world, and to date, there is no cure for it despite extensive research and numerous clinical trials. Several biomarkers have been identified, but no effective therapeutic targets are available. Human galectin-3 is a chimeric gene product formed by the fusion of the internal domain of the collagen alpha gene [N-terminal domain (ND)] at the 5′-end of galectin-1 [C-terminal domain (CRD)] that appeared during evolution together with vertebrates. Due to the overlapping structural similarities between collagen and galectin-3 and their shared susceptibility to cleavage by matrix metalloproteases to generate circulating collagen-like peptides, this review will discuss present knowledge on the role of collagen and galectin-3 as biomarkers of fibrosis. We will also highlight the need for transformative approaches targeting both the ND and CRD domains of galectin-3, since glycoconjugate binding by the CRD is triggered by ND-mediated oligomerization and the therapies targeted only at the CRD have so far achieved limited success.

      Keywords

      Abbreviations:

      CITP (C-terminal fragment of collagen type I degradation), COPD (chronic obstructive pulmonary disease), ECM (extracellular matrix), ILD (interstitial lung disease), IPF (idiopathic pulmonary fibrosis), MCP (modified citrus pectin), MMP (matrix metalloprotease), NASH (nonalcoholic steatohepatitis), ND (N-terminus domain), PAH (Pulmonary arterial hypertension), PICP (C-terminal propeptide of procollagen type I), PINP (procollagen type I N-terminal propeptide), SSc (systemic sclerosis), TGF-β (transforming growth factor-β)
      The extracellular matrix (ECM) is the noncellular scaffold structure present within all tissues and organs, composed mainly of proteoglycans and fibrous proteins. It is crucial for tissue morphogenesis, differentiation, and homeostasis. ECM can be divided into basement membrane and interstitial matrix. The basement membrane, which functions as a scaffold for epithelial and endothelial cells, is composed of collagen type IV, laminin, nidogen (enactin), and perlecan. The major component is collagen type IV, constituting about 50% of all basement membrane proteins. Laminin is the major noncollagenous component of the basement membrane. The interstitial matrix, mainly produced by fibroblasts and composed of collagen I, III, V, and VI, fibronectin, and proteoglycans makes up the majority of ECM in the body. These components together assemble in a highly cross-linked network, with great functional and compositional variations allowing rapid diffusion of certain small molecules (reviewed in (
      • Genovese F.
      • Karsdal M.A.
      Protein degradation fragments as diagnostic and prognostic biomarkers of connective tissue diseases: understanding the extracellular matrix message and implication for current and future serological biomarkers.
      )).
      Tissue injury knocking out epithelial and endothelial cells and exposure of basement membrane results in an influx of inflammatory cells, such as macrophages and neutrophils into the damaged site. These cells secrete proteases to degrade the basement membrane and release the fragments of component proteins into circulation. To repair the basement membrane, the activated fibroblasts secrete new proteins to substitute the degraded proteins (Fig. 1A). This results in wound healing. In case of chronic inflammation, the deeper tissues including the interstitial layer of ECM are exposed and get damaged. Several inflammatory cytokines including the interleukins (
      • Nikolic-Paterson D.J.
      • Main I.W.
      • Tesch G.H.
      • Lan H.Y.
      • Atkins R.C.
      Interleukin-1 in renal fibrosis.
      ,
      • O'Reilly S.
      • Ciechomska M.
      • Cant R.
      • Hugle T.
      • van Laar J.M.
      Interleukin-6, its role in fibrosing conditions.
      ) and members of transforming growth factor-β (TGF-β) (
      • Wu N.
      • Meng F.
      • Invernizzi P.
      • Bernuzzi F.
      • Venter J.
      • Standeford H.
      • et al.
      The secretin/secretin receptor axis modulates liver fibrosis through changes in transforming growth factor-beta1 biliary secretion in mice.
      ,
      • Walton K.L.
      • Johnson K.E.
      • Harrison C.A.
      Targeting TGF-beta mediated SMAD signaling for the prevention of fibrosis.
      ) secreted by platelets, endothelial cells, smooth muscle cells, and macrophages act on fibroblasts to induce proliferation and differentiation. The differentiated fibroblasts continue to secrete proteins leading to disproportionate accumulation of collagen in the interstitial space, causing scarring of the affected organ (
      • Genovese F.
      • Karsdal M.A.
      Protein degradation fragments as diagnostic and prognostic biomarkers of connective tissue diseases: understanding the extracellular matrix message and implication for current and future serological biomarkers.
      ) (Fig. 1B). Galectin-3 is a profibrotic molecule regulating the functions of macrophages and fibroblasts in response to inflammation. It was shown that increased galectin-3 expression further activates myofibroblasts leading to wound scarring and is thus implicated in inflamed organ’s ‘fibrosis’(Fig. 1). On the other hand, its deficiency leads to reduced fibrotic response.
      Figure thumbnail gr1
      Figure 1Schematic presentation of wound healing and fibrosis: (A) Cell death resulting from tissue injury results in recruitment of inflammatory cells through the damaged epithelium. These cells secrete proteases, degrade basement membrane, and release the components into circulation. Galectin-3 and TGF-β secreted by macrophages activate the resting fibroblasts into myofibroblasts, which secrete fresh basement membrane resulting in wound healing. The synthetic and degradative processes are in balance. (B) Constant and repetitive injury induces damage to the deeper interstitial layer and results in overproduction of the basement membrane components in an unorganized way leading to fibrosis. Secretion of IL-4 and IL-13 by inflammatory cells activates alternative macrophages, activated macrophages secrete increased galectin-3 and overexpress its cell surface receptor CD98. Galectin-3 and CD98 binding stabilizes CD98 and activates PI3K via an association with phosphorylated FAK and β-1 integrin. A galectin-3 feedback loop drives alternative macrophage activation. (Adapted from Genovese and Karsdal, 2016, Expert Review of Proteomics, 13 (
      • Nikolic-Paterson D.J.
      • Main I.W.
      • Tesch G.H.
      • Lan H.Y.
      • Atkins R.C.
      Interleukin-1 in renal fibrosis.
      ), 213–225).
      The abnormal remodeling of the ECM is related to a plethora of fibroproliferative diseases of various organs including heart, liver, lung, kidneys, skin, and some systemic disorders such as systemic sclerosis, atherosclerosis, and cystic fibrosis (Fig. 2) and is responsible for nearly 45% of all deaths (
      • Wynn T.A.
      Fibrotic disease and the T(H)1/T(H)2 paradigm.
      ). The mechanism of fibrosis is similar in various organs as all epithelial tissues such as skin, digestive tract, pulmonary organs, genitourinary tracts, and endothelial cells of blood vessels, as well as mesothelial cells in the body cavities, are lined by ECM (
      • Mak K.M.
      • Mei R.
      Basement membrane type IV collagen and laminin: an overview of their biology and value as fibrosis biomarkers of liver disease.
      ,
      • Vracko R.
      Basal lamina scaffold-anatomy and significance for maintenance of orderly tissue structure.
      ). In recent years, fibroproliferative process has been the focus of interest as a candidate for disease intervention. The noninvasive method of detecting fibrosis is by analyzing the levels of circulating biomarkers. Several biomarkers have been studied including collagen-related peptides, matrix metalloproteases (MMPs), tissue inhibitors of metalloproteases, selected miRNAs, galectin-3, and several noncollagen-related peptides. Among these, collagen peptides and galectin-3 appear to be most promising as reflecting combined effects of injury, inflammation, and fibrosis. In this review, we have selected the liver, heart, and lung as representative organs of fibroproliferative diseases, and we will discuss the current knowledge on these two proteins and their peptides as biomarkers of fibrosis and disease progression and value of galectin-3 as a therapeutic target.
      Figure thumbnail gr2
      Figure 2Fibroproliferative diseases: Various organs develop fibrotic scars as a result of constant tissue damage and insults. FSGS, focal segmental glomerlosclerosis; NASH, nonalcoholic steatohepatitis; AMD, age-related macular degeneration; COPD, chronic obstructive pulmonary disease. (Adapted from Karsdal et al, 2014 Alimentary Pharmacology and Therapeutics, 40: 233–249)

      Biomarkers of fibrosis

      Collagens

      Collagens are a superfamily of 28 members comprising the most abundant proteins in humans. The common feature of all family members is a triple helix structure made up of three polypeptide chains, which can either be homotrimers (3 identical α chains) or heterotrimers (nonidentical α chains) and are of variable lengths in different members. Collagens are characterized by their capacity to form supramolecular assemblies (
      • Karsdal M.A.
      • Daniels S.J.
      • Holm Nielsen S.
      • Bager C.
      • Rasmussen D.G.K.
      • Loomba R.
      • et al.
      Collagen biology and non-invasive biomarkers of liver fibrosis.
      ). Based on the supramolecular structure, the collagens can be fibrils, beaded filaments, anchoring fibrils, and networks (
      • Ricard-Blum S.
      The collagen family.
      ). Further diversity in the collagen family is due to the several molecular isoforms as well as alternative splicing and alternative promoters. Collagens are synthesized as procollagens and cleaved to mature form. The mature collagens are enzymatically cleaved and released as biologically active fragments (
      • Ricard-Blum S.
      The collagen family.
      ). As collagens are an integral part of the ECM, their deregulated cleavage and reassembly play an important role in fibrosis. Circulating collagen fragments (neoepitopes) as biomarkers of the fibrogenic or fibrolytic events in various diseases have been studied extensively. Propeptides, which are released from procollagen as part of the maturing process, reflect the synthetic process, whereas the degradation epitopes, which are released as part of the degradation process reflect the fibrolytic process (
      • Karsdal M.A.
      • Daniels S.J.
      • Holm Nielsen S.
      • Bager C.
      • Rasmussen D.G.K.
      • Loomba R.
      • et al.
      Collagen biology and non-invasive biomarkers of liver fibrosis.
      ). Various collagen epitopes used as biomarkers have been summarized in Table 1.
      Table 1Major collagen neo-epitopes used as serum biomarkers for fibroproliferative diseases
      Synthesis-related epitopes
      Collagen typeNameDescriptionAffected organ
      Collagen type IPINPAmino-terminal peptide of procollagen type IHeart
      PICPC-terminal peptide of procollagen type IHeart
      Collagen type IIIPIIINPAmino-terminal peptide of procollagen Type IIILiver, heart, and lung
      Pro C3A fragment of N-terminal type III collagenLung
      Collagen type IVP4NP77S domain of type IV collagenLiver
      NC-1Carboxy-terminal region of alpha chainLiver
      Collagen type VIProC6A fragment of C-terminal type VIa3 collagenLung
      Degradation-related epitopes
      Collagen typeNameDescriptionAffected organ
      Collagen type ICIMMMP degraded fragment of Collagen type ILung
      CITPCarboxy terminal telopeptide of collagen IHeart
      Collagen type IIIC3MMMP degraded fragment of Type III collagenLiver, Lung
      C3AADAMTS degraded fragment of type III collagenLung
      Collagen type IVC4MMMP degraded fragment of type IV collagenLiver
      Collagen type VC5MMMP degraded fragment of type V collagenLung
      Collagen type VIC6MMMP degraded fragment of type VI collagenLung

      Galectin-3

      Human galectin-3 (LGALS3), a protein of 31Kda (
      • Raz A.
      • Pazerini G.
      • Carmi P.
      Identification of the metastasis-associated, galactoside-binding lectin as a chimeric gene product with homology to an IgE-binding protein.
      ,
      • Raz A.
      • Carmi P.
      • Raz T.
      • Hogan V.
      • Mohamed A.
      • Wolman S.R.
      Molecular cloning and chromosomal mapping of a human galactoside-binding protein.
      ), belongs to the galectin gene family of carbohydrate-binding proteins and is the only member that is expressed in vertebrates. All of the galectin family members contain a conserved carbohydrate-binding domain of ∼130 amino acids. Galectins have been divided into three subtypes based on their structure: prototype, tandem repeat, and chimera. Galectin-3 is the only chimera (fused) protein consisting of three distinct structural motifs: a short 12 amino acid N-terminal motif, followed by a long collagen α-like sequence (collagen α) and a C-terminal carbohydrate-binding domain (galectin-1).
      The short N-terminal motif contains a site of serine6 phosphorylation for controlling the nuclear transport and ligand affinity (
      • Gong H.C.
      • Honjo Y.
      • Nangia-Makker P.
      • Hogan V.
      • Mazurak N.
      • Bresalier R.S.
      • et al.
      The NH2 terminus of galectin-3 governs cellular compartmentalization and functions in cancer cells.
      ). The long and intrinsically disorganized collagen α like proline-rich sequence of about 110 amino acids (ND) is cleavable by MMPs -2, -9, and membrane type 1 MMP at the Ala62-Tyr63 bond, resulting in the generation of a cleaved fragment of 22kD (
      • Ochieng J.
      • Fridman R.
      • Nangia-Makker P.
      • Kleiner D.E.
      • Liotta L.A.
      • Stetler-Stevenson W.G.
      • et al.
      Galectin-3 is a novel substrate for human matrix metalloproteinases-2 and -9.
      ) (Fig. 3). The C-terminal domain (CRD), consisting of about 130 amino acids, is the common domain shared by all galectin family members and is responsible for their lectin activity. Galectin-3 has a preferential binding for N-acetyllactosamine residues on cell surface glycoconjugates. Galectin-3 interacts with several ligands both intracellularly and extracellularly and influences various pathways and processes via its CRD binding activity. It binds Bcl-2, CD95, Nucling, Alix/AIP1, synexin, and regulates apoptosis. Its interaction with activated K-Ras protein affects cell proliferation and survival. β-catenin is its binding partner in the Wnt signaling pathway. Galectin-3 binds to laminin, fibronectin, hensin, elastin, collagen IV, and tenascin-C and tenascin-R to modulate cell–ECM adhesion. In addition, it also binds α1β1, αvβ3, and αMβ1 integrins, the main proteins involved in cell adhesion (Table 2).
      Figure thumbnail gr3
      Figure 3Molecular structure of galectin-1(top left) and galectin-3 (top right). Lower panel: cleaved galectin-3 N-terminal and C-terminal. Visualization and analysis was done by YASARA model software.
      A germ-line mutation at position 191 (rs4644) substituting amino acid proline64 to histidine makes this protein susceptible to MMP cleavage and enhances its migratory and angiogenic potential (
      • Nangia-Makker P.
      • Raz T.
      • Tait L.
      • Hogan V.
      • Fridman R.
      • Raz A.
      Galectin-3 cleavage: a novel surrogate marker for matrix metalloproteinase activity in growing breast cancers.
      ,
      • Balan V.
      • Nangia-Makker P.
      • Schwartz A.G.
      • Jung Y.S.
      • Tait L.
      • Hogan V.
      • et al.
      Racial disparity in breast cancer and functional germ line mutation in galectin-3 (rs4644): a pilot study.
      ). It was reported that cleaved galectin-3 had stronger affinity for glycoconjugates than the full-length protein (
      • Ochieng J.
      • Green B.
      • Evans S.
      • James O.
      • Warfield P.
      Modulation of the biological functions of galectin-3 by matrix metalloproteinases.
      ), while some other interactions require both N-terminus domain and CRD motifs. Galectin-3 displays multivalency by the hydrophobic interactions of the N terminal with itself and with the CRD forming a fuzzy complex, which is the characteristic of intrinsically disordered proteins to achieve liquid–liquid phase separation (
      • Lin Y.H.
      • Qiu D.C.
      • Chang W.H.
      • Yeh Y.Q.
      • Jeng U.S.
      • Liu F.T.
      • et al.
      The intrinsically disordered N-terminal domain of galectin-3 dynamically mediates multisite self-association of the protein through fuzzy interactions.
      ). Additional functional oligomeric states exist due to the dynamic homodimerization of the N terminal. It is generally accepted that galectin-3 oligomerization gives rise to changes in activity, which are associated with and reflected in its diverse biological functions. Galectin-3 oligomer forms a lattice with T cell surface receptors that prevents their uncontrolled activation (
      • Demetriou M.
      • Granovsky M.
      • Quaggin S.
      • Dennis J.W.
      Negative regulation of T-cell activation and autoimmunity by Mgat5 N-glycosylation.
      ), and its cross-linking with either EGF and TGF-β receptors delays their internalization and degradation (
      • Pugliese G.
      • Iacobini C.
      • Pesce C.M.
      • Menini S.
      Galectin-3: an emerging all-out player in metabolic disorders and their complications.
      ). Table 2 reflects the several biological processes regulated by C-terminal and N-terminal domains of galectin-3 in association with various binding partners.
      Table 2Binding partners of galectin-3 C-terminal and N-terminal
      C-terminalFunctionReference
      Bcl2ApoptosisYang et al, 1996 (
      • Yang R.Y.
      • Hsu D.K.
      • Liu F.T.
      Expression of galectin-3 modulates T-cell growth and apoptosis.
      )
      CD95ApoptosisFukumori et al, 2004 (
      • Fukumori T.
      • Takenaka Y.
      • Oka N.
      • Yoshii T.
      • Hogan V.
      • Inohara H.
      • et al.
      Endogenous galectin-3 determines the routing of CD95 apoptotic signaling pathways.
      )
      NuclingApoptosisLiu et al, 2004 (
      • Liu L.
      • Sakai T.
      • Sano N.
      • Fukui K.
      Nucling mediates apoptosis by inhibiting expression of galectin-3 through interference with nuclear factor kappaB signalling.
      )
      Alix/AIP1ApoptosisLiu et al, 2002 (
      • Liu F.T.
      • Patterson R.J.
      • Wang J.L.
      Intracellular functions of galectins.
      )
      K-RasCell proliferationEelad-sfadia et al, 2004 (
      • Elad-Sfadia G.
      • Haklai R.
      • Balan E.
      • Kloog Y.
      Galectin-3 augments K-Ras activation and triggers a Ras signal that attenuates ERK but not phosphoinositide 3-kinase activity.
      )
      AktCell ProliferationLee et al, 2003 (
      • Lee Y.J.
      • Song Y.K.
      • Song J.J.
      • Siervo-Sassi R.R.
      • Kim H.R.
      • Li L.
      • et al.
      Reconstitution of galectin-3 alters glutathione content and potentiates TRAIL-induced cytotoxicity by dephosphorylation of Akt.
      ), Oka et al, 2005 (
      • Oka N.
      • Nakahara S.
      • Takenaka Y.
      • Fukumori T.
      • Hogan V.
      • Kanayama H.O.
      • et al.
      Galectin-3 inhibits tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by activating Akt in human bladder carcinoma cells.
      )
      β-cateninWnt signalingShimura et al, 2004 (
      • Shimura T.
      • Takenaka Y.
      • Tsutsumi S.
      • Hogan V.
      • Kikuchi A.
      • Raz A.
      Galectin-3, a novel binding partner of beta-catenin.
      )
      LamininECM adhesionMassa et al, 1993 (
      • Massa S.M.
      • Cooper D.N.
      • Leffler H.
      • Barondes S.H.
      L-29, an endogenous lectin, binds to glycoconjugate ligands with positive cooperativity.
      ),
      FibronectinECM adhesionSato et al, 1992 (
      • Sato S.
      • Hughes R.C.
      Binding specificity of a baby hamster kidney lectin for H type I and II chains, polylactosamine glycans, and appropriately glycosylated forms of laminin and fibronectin.
      )
      HensinECM adhesionHikita et al, 2000 (
      • Hikita C.
      • Vijayakumar S.
      • Takito J.
      • Erdjument-Bromage H.
      • Tempst P.
      • Al-Awqati Q.
      Induction of terminal differentiation in epithelial cells requires polymerization of hensin by galectin 3.
      )
      ElastinECM adhesionOchieng et al, 1998 (
      • Ochieng J.
      • Warfield P.
      • Green-Jarvis B.
      • Fentie I.
      Galectin-3 regulates the adhesive interaction between breast carcinoma cells and elastin.
      )
      Collagen IVECM adhesionOchieng et al, 1998 (
      • Ochieng J.
      • Leite-Browning M.L.
      • Warfield P.
      Regulation of cellular adhesion to extracellular matrix proteins by galectin-3.
      )
      Tenascin-C&-RECM adhesionProbstmeier et al, 1995 (
      • Probstmeier R.
      • Montag D.
      • Schachner M.
      Galectin-3, a beta-galactoside-binding animal lectin, binds to neural recognition molecules.
      ))
      α1β1 integrinCell adhesionOchieng et al, 1998 (
      • Ochieng J.
      • Leite-Browning M.L.
      • Warfield P.
      Regulation of cellular adhesion to extracellular matrix proteins by galectin-3.
      )
      CD11b/CD18Inflammatory macrophageDong et al, 1997 (
      • Dong S.
      • Hughes R.C.
      Macrophage surface glycoproteins binding to galectin-3 (Mac-2-antigen).
      )
      Lamp-1 and -2Inflammatory macrophageDong et al, 1997 (
      • Dong S.
      • Hughes R.C.
      Macrophage surface glycoproteins binding to galectin-3 (Mac-2-antigen).
      )
      IgEInflammationCherayil et al, 1989 (
      • Cherayil B.J.
      • Weiner S.J.
      • Pillai S.
      The Mac-2 antigen is a galactose-specific lectin that binds IgE.
      )
      CD44Cargo protein internalizationLakshminarayan et al, 2014 (
      • Lakshminarayan R.
      • Wunder C.
      • Becken U.
      • Howes M.T.
      • Benzing C.
      • Arumugam S.
      • et al.
      Galectin-3 drives glycosphingolipid-dependent biogenesis of clathrin-independent carriers.
      )
      CD98Membrane traffickingDalton et al, 2007 (
      • Dalton P.
      • Christian H.C.
      • Redman C.W.
      • Sargent I.L.
      • Boyd C.A.
      Membrane trafficking of CD98 and its ligand galectin 3 in BeWo cells–implication for placental cell fusion.
      )
      CD66Inflammatory neutrophilsFeuk-Lagersted et al,1999 (
      • Feuk-Lagerstedt E.
      • Movitz C.
      • Pellme S.
      • Dahlgren C.
      • Karlsson A.
      Lipid raft proteome of the human neutrophil azurophil granule.
      )
      N-terminalFunctionReference
      EGFRCross-linking & endocytosisPartridge et al, 2004 (
      • Partridge E.A.
      • Le Roy C.
      • Di Guglielmo G.M.
      • Pawling J.
      • Cheung P.
      • Granovsky M.
      • et al.
      Regulation of cytokine receptors by Golgi N-glycan processing and endocytosis.
      ); Liu 2012 (
      • Liu W.
      • Hsu D.K.
      • Chen H.Y.
      • Yang R.Y.
      • Carraway 3rd, K.L.
      • Isseroff R.R.
      • et al.
      Galectin-3 regulates intracellular trafficking of EGFR through Alix and promotes keratinocyte migration.
      )
      TGFβRCross linking& endocytosisPartridge et al, 2004 (
      • Partridge E.A.
      • Le Roy C.
      • Di Guglielmo G.M.
      • Pawling J.
      • Cheung P.
      • Granovsky M.
      • et al.
      Regulation of cytokine receptors by Golgi N-glycan processing and endocytosis.
      )
      CD147Clustering &MMP9 inductionMauris et al, 2014 (
      • Mauris J.
      • Woodward A.M.
      • Cao Z.
      • Panjwani N.
      • Argueso P.
      Molecular basis for MMP9 induction and disruption of epithelial cell-cell contacts by galectin-3.
      )
      AlixHIV infectionWang et al, 2014 (
      • Wang S.F.
      • Tsao C.H.
      • Lin Y.T.
      • Hsu D.K.
      • Chiang M.L.
      • Lo C.H.
      • et al.
      Galectin-3 promotes HIV-1 budding via association with Alix and Gag p6.
      )
      AlixT cell receptor (TCR) downregulationChen et al, 2009 (
      • Chen H.Y.
      • Fermin A.
      • Vardhana S.
      • Weng I.C.
      • Lo K.F.
      • Chang E.Y.
      • et al.
      Galectin-3 negatively regulates TCR-mediated CD4+ T-cell activation at the immunological synapse.
      )
      Bacterial LPSInflammationLo et al, 2021 (
      • Lo T.H.
      • Chen H.L.
      • Yao C.I.
      • Weng I.C.
      • Li C.S.
      • Huang C.C.
      • et al.
      Galectin-3 promotes noncanonical inflammasome activation through intracellular binding to lipopolysaccharide glycans.
      )
      Abbreviations: Alix, ALG2 interacting protein X; CEA, carcinoembryonic antigen.
      Galectin-3 is a profibrotic molecule and implicated in modulation of fibroblasts and macrophage activity in chronically inflamed lung, liver, kidney, heart, skin, blood vessels, etc. affecting common fibroproliferative pathways leading to fibrosis (
      • Hara A.
      • Niwa M.
      • Noguchi K.
      • Kanayama T.
      • Niwa A.
      • Matsuo M.
      • et al.
      Galectin-3 as a next-generation biomarker for detecting early stage of various diseases.
      ,
      • Miah A.
      • S P.
      • Tongue P.
      • Roach K.
      • Bradding P.
      • Gooptu B.
      Ex vivo studies of the gal-3-fibrosome hypothesis in IPF and non-fibrotic control lung tissue and myofibroblasts..
      ). It is a proinflammatory molecule (
      • Liu F.T.
      • Hsu D.K.
      The role of galectin-3 in promotion of the inflammatory response.
      ). It regulates immune functions and mediates acute and chronic inflammation. It activates and is abundantly expressed in cells of myeloid origin, such as monocytes, macrophages, dendritic cells, and neutrophils (
      • Fulton D.J.R.
      • Li X.
      • Bordan Z.
      • Wang Y.
      • Mahboubi K.
      • Rudic R.D.
      • et al.
      Galectin-3: a harbinger of reactive oxygen species, fibrosis, and inflammation in pulmonary arterial hypertension.
      ). It interacts with inflammatory cytokines TGF-β and CD98 expressed by migrating inflammatory cells and plays a major role in the profibrotic response (
      • Walton K.L.
      • Johnson K.E.
      • Harrison C.A.
      Targeting TGF-beta mediated SMAD signaling for the prevention of fibrosis.
      ). In galectin-3–deficient mice, a dramatic reduction in fibrosis in response to TGF-β and bleomycin was observed accompanied with reduced epithelial to mesenchymal transition and myofibroblast activation (
      • MacKinnon A.C.
      • Farnworth S.L.
      • Hodkinson P.S.
      • Henderson N.C.
      • Atkinson K.M.
      • Leffler H.
      • et al.
      Regulation of alternative macrophage activation by galectin-3.
      ,
      • Mackinnon A.C.
      • Gibbons M.A.
      • Farnworth S.L.
      • Leffler H.
      • Nilsson U.J.
      • Delaine T.
      • et al.
      Regulation of transforming growth factor-beta1-driven lung fibrosis by galectin-3.
      ). Galectin-3 is instrumental in TGF-β1–induced fibroblasts differentiation via the MAPK/extracellular signal-regulated kinase (ERK)-ERK 1/2 signaling pathway (Fig. 1). It aids the extravasation of inflammatory cells and binds to specific cell surface receptors on macrophages (CD11b, CD98) and on neutrophils (CD66). It is upregulated in alternative macrophage activation by IL4 and IL13, and it activates PI3K via binding to CD98 and aids in increased collagen deposition (
      • Sato S.
      • Ouellet N.
      • Pelletier I.
      • Simard M.
      • Rancourt A.
      • Bergeron M.G.
      Role of galectin-3 as an adhesion molecule for neutrophil extravasation during streptococcal pneumonia.
      ,
      • Dong S.
      • Hughes R.C.
      Macrophage surface glycoproteins binding to galectin-3 (Mac-2-antigen).
      ) by differentiation of resting fibroblasts into myofibroblasts leading to scar formation (
      • Slack R.J.
      • Mills R.
      • Mackinnon A.C.
      The therapeutic potential of galectin-3 inhibition in fibrotic disease.
      ) (Fig. 1).

      Hepatic fibrosis

      Hepatitis B and Hepatitis C virus infections, innate immunity, and chronic inflammation play a role in the pathogenesis of liver metabolic disorders, nonalcoholic fatty liver disease, liver steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Chronic liver disease and cirrhosis result in ∼35,000 deaths each year in the US and for approximately two million deaths per year worldwide.
      The major histological components of the liver consist of (i) hepatocytes, constituting the parenchyma, (ii) stroma, (iii) sinusoids (the capillaries travelling between hepatocytes), and (iv) the spaces of Disse, which are located between the hepatocytes and the sinusoids. The liver sinusoids are a unique structure and are classified as discontinuous capillaries as they do not have a continuous endothelial lining but are endowed with fenestrated endothelium, which enables liver functions like ultrafiltration, endocytosis, and immunological activities. The spaces of Disse is enriched in collagen IV and perlecan but lacks laminin and nidogen (other components of the basement membrane). Sinusoidal capillarization is characterized by the formation of the basal lamina, loss of fenestrae, and transformation of the sinusoids into the continuous capillary. This interferes with hepatic microcirculation and leads to hepatic dysfunction (
      • Martinez-Hernandez A.
      • Martinez J.
      The role of capillarization in hepatic failure: studies in carbon tetrachloride-induced cirrhosis.
      ). The capillarization of sinusoids is the basic remodeling in all chronic liver diseases, accompanied with increased collagen IV and laminin deposits in the spaces of Disse.

      Collagen fragments as biomarkers of hepatic fibrosis

      Collagen IV expression levels were used to distinguish between the early and late stages of fibrosis in hepatitis C-related fibrosis (
      • Chen W.
      • Rock J.B.
      • Yearsley M.M.
      • Ferrell L.D.
      • Frankel W.L.
      Different collagen types show distinct rates of increase from early to late stages of hepatitis C-related liver fibrosis.
      ). A 14-fold increase in collagen IV was observed in liver cirrhosis (
      • Rojkind M.
      • Ponce-Noyola P.
      The extracellular matrix of the liver.
      ), and the levels were higher in alcoholic than in nonalcoholic hepatitis and cirrhosis (
      • Ueno T.
      • Inuzuka S.
      • Torimura T.
      • Oohira H.
      • Ko H.
      • Obata K.
      • et al.
      Significance of serum type-IV collagen levels in various liver diseases. Measurement with a one-step sandwich enzyme immunoassay using monoclonal antibodies with specificity for pepsin-solubilized type-IV collagen.
      ,
      • Hirayama C.
      • Suzuki H.
      • Takada A.
      • Fujisawa K.
      • Tanikawa K.
      • Igarashi S.
      Serum type IV collagen in various liver diseases in comparison with serum 7S collagen, laminin, and type III procollagen peptide.
      ). In addition, neoepitopes of collagen IV: 7S and NCI (noncollagenous C-terminal domain of collagen IV) domains have been studied as noninvasive biomarkers of chronic liver disease. A correlation between the serum 7S collagen fragment levels and liver fibrosis grade was observed in chronic hepatitis C (
      • Murawaki Y.
      • Ikuta Y.
      • Koda M.
      • Yamada S.
      • Kawasaki H.
      Comparison of serum 7S fragment of type IV collagen and serum central triple-helix of type IV collagen for assessment of liver fibrosis in patients with chronic viral liver disease.
      ), and these levels were much higher in chronic hepatitis C with cirrhosis (
      • Sakugawa H.
      • Nakayoshi T.
      • Kobashigawa K.
      • Yamashiro T.
      • Maeshiro T.
      • Miyagi S.
      • et al.
      Clinical usefulness of biochemical markers of liver fibrosis in patients with nonalcoholic fatty liver disease.
      ,
      • Yoneda M.
      • Mawatari H.
      • Fujita K.
      • Yonemitsu K.
      • Kato S.
      • Takahashi H.
      • et al.
      Type IV collagen 7s domain is an independent clinical marker of the severity of fibrosis in patients with nonalcoholic steatohepatitis before the cirrhotic stage.
      ). A similar relationship was observed with NCI and progressive liver disease cirrhosis, when compared with chronic active hepatitis (
      • Hayasaka A.
      • Schuppan D.
      • Ohnishi K.
      • Okuda K.
      • Hahn E.G.
      Serum concentrations of the carboxyterminal cross-linking domain of procollagen type IV (NC1) and the aminoterminal propeptide of procollagen type III (PIIIP) in chronic liver disease.
      ,
      • Babbs C.
      • Haboubi N.Y.
      • Mellor J.M.
      • Smith A.
      • Rowan B.P.
      • Warnes T.W.
      Endothelial cell transformation in primary biliary cirrhosis: a morphological and biochemical study.
      ). To date, the most used marker of liver fibrosis is the amino-terminal peptide of procollagen type III (PIIINP) (
      • Siddiqui M.S.
      • Yamada G.
      • Vuppalanchi R.
      • Van Natta M.
      • Loomba R.
      • Guy C.
      • et al.
      Diagnostic accuracy of noninvasive fibrosis models to detect change in fibrosis stage.
      ,
      • Peleg N.
      • Sneh Arbib O.
      • Issachar A.
      • Cohen-Naftaly M.
      • Braun M.
      • Shlomai A.
      Noninvasive scoring systems predict hepatic and extra-hepatic cancers in patients with nonalcoholic fatty liver disease.
      ,
      • Nielsen M.J.
      • Kazankov K.
      • Leeming D.J.
      • Karsdal M.A.
      • Krag A.
      • Barrera F.
      • et al.
      Markers of collagen remodeling detect clinically significant fibrosis in chronic hepatitis C patients.
      ) together with C3M, which is an MMP degraded fragment of type III collagen reported to be elevated in liver fibrosis, skin fibrosis, and ankylosing spondylitis (
      • Trinchet J.C.
      • Hartmann D.J.
      • Pateron D.
      • Munz-Gotheil C.
      • Callard P.
      • Ville G.
      • et al.
      Serum type I collagen and N-terminal peptide of type III procollagen in patients with alcoholic liver disease: relationship to liver histology.
      ,
      • Rosenberg W.M.
      • Voelker M.
      • Thiel R.
      • Becka M.
      • Burt A.
      • Schuppan D.
      • et al.
      Serum markers detect the presence of liver fibrosis: a cohort study.
      ,
      • Nielsen M.J.
      • Nedergaard A.F.
      • Sun S.
      • Veidal S.S.
      • Larsen L.
      • Zheng Q.
      • et al.
      The neo-epitope specific PRO-C3 ELISA measures true formation of type III collagen associated with liver and muscle parameters.
      ).

      Galectin-3 as a biomarker of hepatic fibrosis

      Galectin-3–null mice fed high-fat diet exhibited all the symptoms of nonalcoholic fatty liver disease including increased liver weight, elevated triglycerides, hyperglycemia, and hepatic steatosis, as well as inflammation and fibrosis (
      • Rosenberg W.M.
      • Voelker M.
      • Thiel R.
      • Becka M.
      • Burt A.
      • Schuppan D.
      • et al.
      Serum markers detect the presence of liver fibrosis: a cohort study.
      ) subsequently developing liver nodules progressing to hepatocellular carcinoma (
      • Rosenberg W.M.
      • Voelker M.
      • Thiel R.
      • Becka M.
      • Burt A.
      • Schuppan D.
      • et al.
      Serum markers detect the presence of liver fibrosis: a cohort study.
      ,
      • Nielsen M.J.
      • Nedergaard A.F.
      • Sun S.
      • Veidal S.S.
      • Larsen L.
      • Zheng Q.
      • et al.
      The neo-epitope specific PRO-C3 ELISA measures true formation of type III collagen associated with liver and muscle parameters.
      ). However, some other investigators have documented protection from NASH with attenuation of fibrosis, inflammation, and hepatic injury and other symptoms related to high-fat diets such as hepatocyte degeneration and focal necrosis in galectin-3 KO mice (
      • Iacobini C.
      • Menini S.
      • Ricci C.
      • Blasetti Fantauzzi C.
      • Scipioni A.
      • Salvi L.
      • et al.
      Galectin-3 ablation protects mice from diet-induced NASH: a major scavenging role for galectin-3 in liver.
      ,
      • Negre-Salvayre A.
      • Coatrieux C.
      • Ingueneau C.
      • Salvayre R.
      Advanced lipid peroxidation end products in oxidative damage to proteins. Potential role in diseases and therapeutic prospects for the inhibitors.
      ). In the carbon tetrachloride-induced cirrhosis mouse model, galectin-3 played a role in ECM production (
      • Butscheid M.
      • Hauptvogel P.
      • Fritz P.
      • Klotz U.
      • Alscher D.M.
      Hepatic expression of galectin-3 and receptor for advanced glycation end products in patients with liver disease.
      ) and was responsible for diet-induced steatohepatitis through IL-33/ST2 axis (
      • Butscheid M.
      • Hauptvogel P.
      • Fritz P.
      • Klotz U.
      • Alscher D.M.
      Hepatic expression of galectin-3 and receptor for advanced glycation end products in patients with liver disease.
      ).
      The removal of advanced glycation end products and advanced lipidomic end products is performed by the liver and galectin-3 is reported to be directly involved with the endocytosis of these harmful byproducts by the liver's sinusoidal and endothelial cells. In galectin-3–null mice, the circulating levels of advanced glycation end products/advanced lipidomic end products were higher than the control mice (
      • Iacobini C.
      • Menini S.
      • Ricci C.
      • Blasetti Fantauzzi C.
      • Scipioni A.
      • Salvi L.
      • et al.
      Galectin-3 ablation protects mice from diet-induced NASH: a major scavenging role for galectin-3 in liver.
      ,
      • Negre-Salvayre A.
      • Coatrieux C.
      • Ingueneau C.
      • Salvayre R.
      Advanced lipid peroxidation end products in oxidative damage to proteins. Potential role in diseases and therapeutic prospects for the inhibitors.
      ), though overexpression of galectin-3 is related to detoxification protection (
      • Butscheid M.
      • Hauptvogel P.
      • Fritz P.
      • Klotz U.
      • Alscher D.M.
      Hepatic expression of galectin-3 and receptor for advanced glycation end products in patients with liver disease.
      ).

      Myocardial fibrosis

      Cardiac fibrosis is a significant worldwide health problem associated with nearly all forms of heart disease causing >650,000 deaths in the US. Formation of a fibrotic scar in the cardiac muscle is a fundamental part of several cardiovascular diseases, such as heart failure (HF), dilated cardiomyopathy, and hypertrophic cardiomyopathy and is characterized by activation and differentiation of cardiac fibroblasts into myofibroblasts leading to increased matrix stiffness and abnormalities in cardiac function (for review see (
      • Hinderer S.
      • Schenke-Layland K.
      Cardiac fibrosis - a short review of causes and therapeutic strategies.
      )).

      Collagen fragments as biomarkers of myocardial fibrosis

      Both the synthesis and breakdown-related neoepitopes of collagen have been studied as biomarkers of cardiac fibrosis. The major component of the cardiac ECM is collagen type I, which makes fibrillar structures in combination with collagen type III. In addition, collagen type IV, V, and VI are also present in small amounts in the pericellular space and around the myocytes (
      • Eghbali M.
      • Czaja M.J.
      • Zeydel M.
      • Weiner F.R.
      • Zern M.A.
      • Seifter S.
      • et al.
      Collagen chain mRNAs in isolated heart cells from young and adult rats.
      ,
      • Eghbali M.
      • Blumenfeld O.O.
      • Seifter S.
      • Buttrick P.M.
      • Leinwand L.A.
      • Robinson T.F.
      • et al.
      Localization of types I, III and IV collagen mRNAs in rat heart cells by in situ hybridization.
      ,
      • Engvall E.
      • Hessle H.
      • Klier G.
      Molecular assembly, secretion, and matrix deposition of type VI collagen.
      ). Plasma levels of C-terminal propeptide of procollagen type I (PICP), which is released as a byproduct of the maturing process of procollagen type I, were shown to be correlated with the myocardial PICP content and collagen volume fraction as determined histologically in hypertrophic cardiomyopathy (
      • Yang C.
      • Qiao S.
      • Song Y.
      • Liu Y.
      • Tang Y.
      • Deng L.
      • et al.
      Procollagen type I carboxy-terminal propeptide (PICP) and MMP-2 are potential biomarkers of myocardial fibrosis in patients with hypertrophic cardiomyopathy.
      ) and hypertension patients (
      • Ferreira J.P.
      • Rossignol P.
      • Pizard A.
      • Machu J.L.
      • Collier T.
      • Girerd N.
      • et al.
      Potential spironolactone effects on collagen metabolism biomarkers in patients with uncontrolled blood pressure.
      ). However, in a study on the heart failure model in rats, no such correlation was observed (
      • Adamcova M.
      • Baka T.
      • Dolezelova E.
      • Aziriova S.
      • Krajcirovicova K.
      • Karesova I.
      • et al.
      Relations between markers of cardiac remodelling and left ventricular collagen in an isoproterenol-induced heart damage model.
      ) indicating the involvement of other confounding factors such as weight loss and a catabolic state. In a study including 111 patients with decompensated heart failure, serum PICP levels were found to be significantly increased in patients that underwent new hospitalizations or death (
      • Ruiz-Ruiz F.J.
      • Ruiz-Laiglesia F.J.
      • Samperiz-Legarre P.
      • Lasierra-Diaz P.
      • Flamarique-Pascual A.
      • Morales-Rull J.L.
      • et al.
      Propeptide of procollagen type I (PIP) and outcomes in decompensated heart failure.
      ). These authors concluded that PICP could be used as an independent predictive biomarker of heart failure, hospitalization, and death.
      Another synthesis biomarker of collagen type I is the procollagen type I N-terminal propeptide (PINP), a cleavage product by the proteolytic activity of the ADAMTS family (
      • Colige A.
      • Vandenberghe I.
      • Thiry M.
      • Lambert C.A.
      • Van Beeumen J.
      • Li S.W.
      • et al.
      Cloning and characterization of ADAMTS-14, a novel ADAMTS displaying high homology with ADAMTS-2 and ADAMTS-3.
      ). A few studies have examined its validity as a biomarker for fibrosis. Zile et al. in a large case-control study reported that in patients of heart failure with reduced ejection fraction, levels of PINP and PIIINP were higher than the controls (
      • Zile M.R.
      • O'Meara E.
      • Claggett B.
      • Prescott M.F.
      • Solomon S.D.
      • Swedberg K.
      • et al.
      Effects of sacubitril/valsartan on biomarkers of extracellular matrix regulation in patients with HFrEF.
      ). In a rat model of ischemic cardiomyopathy, plasma PINP levels were much higher than the controls (
      • Zhang B.
      • Li X.
      • Chen C.
      • Jiang W.
      • Lu D.
      • Liu Q.
      • et al.
      Renal denervation effects on myocardial fibrosis and ventricular arrhythmias in rats with ischemic cardiomyopathy.
      ). Various studies have shown that serum PIIINP levels can be used as a biomarker of myocardial fibrosis. PIIINP levels in the serum were higher and could be correlated to the cardiac collagen III levels in patients suffering from idiopathic or ischemic dilated cardiomyopathy (
      • Klappacher G.
      • Franzen P.
      • Haab D.
      • Mehrabi M.
      • Binder M.
      • Plesch K.
      • et al.
      Measuring extracellular matrix turnover in the serum of patients with idiopathic or ischemic dilated cardiomyopathy and impact on diagnosis and prognosis.
      ). Higher serum PIIINP levels could also be related to advanced heart diseases (
      • Ding Y.
      • Wang Y.
      • Zhang W.
      • Jia Q.
      • Wang X.
      • Li Y.
      • et al.
      Roles of biomarkers in myocardial fibrosis.
      ).
      MMPs are the matrix metalloproteases that degrade mature collagen into smaller biologically active fragments. A C-terminal fragment of collagen type I degradation (CITP) has been of interest as a biomarker of fibrolysis. There are some controversial data on the relationship of CITP to heart disease. Lombardi et al. in a cross-sectional study demonstrated that levels of CITP were higher, while the levels of fibrogenic markers of collagen type I (PICP and PINP) were not affected indicating a shift toward the breakdown of collagen type I in hypertrophic cardiomyopathy patients (
      • Lombardi R.
      • Betocchi S.
      • Losi M.A.
      • Tocchetti C.G.
      • Aversa M.
      • Miranda M.
      • et al.
      Myocardial collagen turnover in hypertrophic cardiomyopathy.
      ). Similarly, elevated serum CITP levels were observed in patients with heart failure and atrial fibrillation (
      • Morine K.J.
      • Paruchuri V.
      • Qiao X.
      • Mohammad N.
      • McGraw A.
      • Yunis A.
      • et al.
      Circulating multimarker profile of patients with symptomatic heart failure supports enhanced fibrotic degradation and decreased angiogenesis.
      ,
      • Kallergis E.M.
      • Manios E.G.
      • Kanoupakis E.M.
      • Mavrakis H.E.
      • Arfanakis D.A.
      • Maliaraki N.E.
      • et al.
      Extracellular matrix alterations in patients with paroxysmal and persistent atrial fibrillation: biochemical assessment of collagen type-I turnover.
      ). Circulating levels of CITP were considered as an independent prognostic biomarker of acute myocardial infarction–related death (
      • Manhenke C.
      • Orn S.
      • Squire I.
      • Radauceanu A.
      • Alla F.
      • Zannad F.
      • et al.
      The prognostic value of circulating markers of collagen turnover after acute myocardial infarction.
      ). However, another study did not find a correlation of circulating CITP levels with either cardiac collagen type I and III expression levels or with other left ventricle remodeling parameters (
      • Nagao K.
      • Inada T.
      • Tamura A.
      • Kajitani K.
      • Shimamura K.
      • Yukawa H.
      • et al.
      Circulating markers of collagen types I, III, and IV in patients with dilated cardiomyopathy: relationships with myocardial collagen expression.
      ). Ding et al. (
      • Ding Y.
      • Wang Y.
      • Zhang W.
      • Jia Q.
      • Wang X.
      • Li Y.
      • et al.
      Roles of biomarkers in myocardial fibrosis.
      ) stated that CITP levels may have a diagnostic and prognostic value in myocardial fibrosis.

      Galectin-3 as a biomarker of myocardial fibrosis

      Several cardiovascular diseases, especially those that result from chronic inflammation, have been associated with increased serum galectin-3 levels. In 2017, the American Heart Association recommended that plasma levels of galectin-3 could be used as a risk factor and prognosis biomarker of heart failure (
      • Chow S.L.
      • Maisel A.S.
      • Anand I.
      • Bozkurt B.
      • de Boer R.A.
      • Felker G.M.
      • et al.
      Role of biomarkers for the prevention, assessment, and management of heart failure: a scientific statement from the American heart association.
      ). A pooled analysis of data from three cohorts (COACH, PRIDE, and UDM H-23258) showed that plasma galectin-3 concentration > 17.8 ng/ml was predictive of rehospitalizations in heart failure patients (
      • Meijers W.C.
      • Januzzi J.L.
      • deFilippi C.
      • Adourian A.S.
      • Shah S.J.
      • van Veldhuisen D.J.
      • et al.
      Elevated plasma galectin-3 is associated with near-term rehospitalization in heart failure: a pooled analysis of 3 clinical trials.
      ). Several other studies have shown a positive correlation between serum galectin-3 levels and prognosis for heart failure (
      • Imran T.F.
      • Shin H.J.
      • Mathenge N.
      • Wang F.
      • Kim B.
      • Joseph J.
      • et al.
      Meta-analysis of the usefulness of plasma galectin-3 to predict the risk of mortality in patients with heart failure and in the general population.
      ,
      • Chen H.
      • Chen C.
      • Fang J.
      • Wang R.
      • Nie W.
      Circulating galectin-3 on admission and prognosis in acute heart failure patients: a meta-analysis.
      ,
      • Felker G.M.
      • Fiuzat M.
      • Shaw L.K.
      • Clare R.
      • Whellan D.J.
      • Bettari L.
      • et al.
      Galectin-3 in ambulatory patients with heart failure: results from the HF-action study.
      ); however, some reports did not find such a correlation (
      • Demissei B.G.
      • Cotter G.
      • Prescott M.F.
      • Felker G.M.
      • Filippatos G.
      • Greenberg B.H.
      • et al.
      A multimarker multi-time point-based risk stratification strategy in acute heart failure: results from the RELAX-AHF trial.
      ,
      • Tummalapalli S.L.
      • Zelnick L.R.
      • Andersen A.H.
      • Christenson R.H.
      • deFilippi C.R.
      • Deo R.
      • et al.
      Association of cardiac biomarkers with the Kansas city cardiomyopathy questionnaire in patients with chronic kidney disease without heart failure.
      ). In their recent review, Blanda et al. concluded that galectin-3 has a prognostic value for HF patients, but its value in the prediction of early diagnosis of HF is not so certain (
      • Blanda V.
      • Bracale U.M.
      • Di Taranto M.D.
      • Fortunato G.
      Galectin-3 in cardiovascular diseases.
      ).
      Atherosclerosis, the plaque deposition in the arteries results from several risk factors including hyperlipidemia, hypertension, diabetes, and insulin resistance. It was shown that patients with unstable plaques had higher circulating galectin-3 levels than those with stable plaques (
      • Falcone C.
      • Lucibello S.
      • Mazzucchelli I.
      • Bozzini S.
      • D'Angelo A.
      • Schirinzi S.
      • et al.
      Galectin-3 plasma levels and coronary artery disease: a new possible biomarker of acute coronary syndrome.
      ). Moreover, a correlation was also shown between the number of compromised vessels and serum galectin-3 levels (
      • Falcone C.
      • Lucibello S.
      • Mazzucchelli I.
      • Bozzini S.
      • D'Angelo A.
      • Schirinzi S.
      • et al.
      Galectin-3 plasma levels and coronary artery disease: a new possible biomarker of acute coronary syndrome.
      ). Several other studies have shown higher levels of galectin-3 in advanced carotid atherosclerosis (
      • Oyenuga A.
      • Folsom A.R.
      • Fashanu O.
      • Aguilar D.
      • Ballantyne C.M.
      Plasma galectin-3 and sonographic measures of carotid atherosclerosis in the atherosclerosis risk in communities study.
      ,
      • Ciaccio M.
      • Agnello L.
      • Bracale U.M.
      • Taranto M.
      • Ciaccio M.
      • Bracale U.M.
      • et al.
      Galectin-3 and Lp(a) plasma concentrations and advanced carotid atherosclerotic plaques: correlation with plaque presence and features.
      ) and demonstrated that galectin-3 is an independent biomarker of advanced atherosclerosis independent of age, sex, LDL cholesterol levels, and history of acute myocardial infarction (
      • Ciaccio M.
      • Agnello L.
      • Bracale U.M.
      • Taranto M.
      • Ciaccio M.
      • Bracale U.M.
      • et al.
      Galectin-3 and Lp(a) plasma concentrations and advanced carotid atherosclerotic plaques: correlation with plaque presence and features.
      ). Galectin-3 was reported to directly affect the functioning of the three cell types involved in the development of atherosclerosis, i.e., the dysfunction of endothelial cells, differentiation of monocytes to macrophages and foam cells, and proliferation and migration of vascular smooth muscle cells (reviewed in (
      • Gao Z.
      • Liu Z.
      • Wang R.
      • Zheng Y.
      • Li H.
      • Yang L.
      Galectin-3 is a potential mediator for atherosclerosis.
      )). Sharma et al. (
      • Sharma U.C.
      • Pokharel S.
      • van Brakel T.J.
      • van Berlo J.H.
      • Cleutjens J.P.
      • Schroen B.
      • et al.
      Galectin-3 marks activated macrophages in failure-prone hypertrophied hearts and contributes to cardiac dysfunction.
      ) demonstrated the conversion of fibroblasts to myofibroblasts by treating the cells with recombinant galectin-3, resulting in the expression of TGF-β, collagen, and cyclin D1. Activation of macrophages by galectin-3 resulted in increased production of IL-4 and IL-13 and ECM deposition (
      • MacKinnon A.C.
      • Farnworth S.L.
      • Hodkinson P.S.
      • Henderson N.C.
      • Atkinson K.M.
      • Leffler H.
      • et al.
      Regulation of alternative macrophage activation by galectin-3.
      ). Galectin-3 also increases the collagen I synthesis in HL-I cardiomyocytes (
      • Song X.
      • Qian X.
      • Shen M.
      • Jiang R.
      • Wagner M.B.
      • Ding G.
      • et al.
      Protein kinase C promotes cardiac fibrosis and heart failure by modulating galectin-3 expression.
      ).
      Ferreira et al. reported that galectin-3 is associated with the onset of left ventricular diastolic dysfunction in postmyocardial infarction patients (
      • Ferreira J.P.
      • Bauters C.
      • Eschalier R.
      • Lamiral Z.
      • Fay R.
      • Huttin O.
      • et al.
      Echocardiographic diastolic function evolution in patients with an anterior Q-wave myocardial infarction: insights from the REVE-2 study.
      ). In a recent study, based on 5805 participants, Mortensen et al. (
      • Mortensen M.B.
      • Fuster V.
      • Muntendam P.
      • Mehran R.
      • Baber U.
      • Sartori S.
      • et al.
      Negative risk markers for cardiovascular events in the elderly.
      ) concluded that low galectin-3 was a useful independent negative predictor of cardiovascular risk. In a long-term follow-up study, patients with high plasma galectin-3 levels showed higher mortality rates (
      • Maiolino G.
      • Rossitto G.
      • Pedon L.
      • Cesari M.
      • Frigo A.C.
      • Azzolini M.
      • et al.
      Galectin-3 predicts long-term cardiovascular death in high-risk patients with coronary artery disease.
      ,
      • Aksan G.
      • Gedikli O.
      • Keskin K.
      • Nar G.
      • Inci S.
      • Yildiz S.S.
      • et al.
      Is galectin-3 a biomarker, a player-or both-in the presence of coronary atherosclerosis?.
      ), while those without acute events showed decreased galectin-3 levels (
      • Swiecki P.
      • Sawicki R.
      • Knapp M.
      • Kaminski K.A.
      • Ptaszynska-Kopczynska K.
      • Sobkowicz B.
      • et al.
      Galectin-3 as the prognostic factor of adverse cardiovascular events in long-term follow up in patients after myocardial infarction-A pilot study.
      ). High serum galectin-3 but not galectin-1 levels were associated with increased incidence of large atherosclerotic stroke (
      • Dong H.
      • Wang Z.H.
      • Zhang N.
      • Liu S.D.
      • Zhao J.J.
      • Liu S.Y.
      Serum Galectin-3 level, not Galectin-1, is associated with the clinical feature and outcome in patients with acute ischemic stroke.
      ) and postoperative stroke in patients undergoing carotid endarterectomy, postoperative cerebrovascular ischemic events (
      • Edsfeldt A.
      • Bengtsson E.
      • Asciutto G.
      • Duner P.
      • Bjorkbacka H.
      • Fredrikson G.N.
      • et al.
      High plasma levels of galectin-3 are associated with increased risk for stroke after carotid endarterectomy.
      ). Galectin-3 distribution was altered in arteries from patients with the peripheral arterial disease; its expression was mainly localized in the middle media layer in peripheral arterial disease patients as compared to the outer adventitia layer in normal arteries (
      • Fort-Gallifa I.
      • Hernandez-Aguilera A.
      • Garcia-Heredia A.
      • Cabre N.
      • Luciano-Mateo F.
      • Simo J.M.
      • et al.
      Galectin-3 in peripheral artery disease. Relationships with markers of oxidative stress and inflammation.
      ).

      Pulmonary fibrosis

      Pulmonary fibrosis is a severe, lifelong lung disease that is nearly always fatal and affects ∼ 128,000 people per year in the US with recorded early mortality of ∼ 40,000 patients per year. It is manifested as lung scarring and results as a pathological response when the compensatory mechanisms for remodeling normal tissue integrity fail after constant and persistent abuses such as lung infection, cigarette smoking, drug, or radiation treatment. When fibrosis of the lung occurs in response to interstitial lung disease (ILD), it is more serious as it is progressive; the worst prognosis has been reported for idiopathic pulmonary fibrosis (IPF) with a median survival of about 3 years after diagnosis. Pulmonary arterial hypertension (PAH) is common in patients with ILD. It is characterized by thickening of the pulmonary wall resulting in high arterial blood pressure contributing to the failure of the right ventricle. In these patients, fibrosis occurs in both the lung blood vessels as well as in the right ventricle (
      • Bennett G.A.
      • Smith F.J.
      Pulmonary hypertension in rats living under compressed air conditions.
      ).

      Collagen fragments as biomarkers of pulmonary fibrosis

      The normal lung tissue contains twice as much type I collagen as type III collagen, with these two being the main collagen types (
      • Hance A.J.
      • Crystal R.G.
      The connective tissue of lung.
      ,
      • Seyer J.M.
      • Hutcheson E.T.
      • Kang A.H.
      Collagen polymorphism in idiopathic chronic pulmonary fibrosis.
      ). It was reported that in early fibrosis, both collagen levels increase, but the ratio changes in favor of type III collagen. In long-standing fibrotic scars mainly collagen I remained (
      • Bateman E.D.
      • Turner-Warwick M.
      • Adelmann-Grill B.C.
      Immunohistochemical study of collagen types in human foetal lung and fibrotic lung disease.
      ,
      • Madri J.A.
      • Furthmayr H.
      Collagen polymorphism in the lung. An immunochemical study of pulmonary fibrosis.
      ,
      • Selman M.
      • Montano M.
      • Ramos C.
      • Chapela R.
      Concentration, biosynthesis and degradation of collagen in idiopathic pulmonary fibrosis.
      ), which is less elastic and contributes to fibrosis-related abnormalities. In addition to increased collagen I and its cross-linking, there is also increased elastin, fibronectin, hyaluronan, and proteoglycans all contributing to the inaccessibility of collagen cleavage sites by the proteolytic enzymes (
      • Bensadoun E.S.
      • Burke A.K.
      • Hogg J.C.
      • Roberts C.R.
      Proteoglycan deposition in pulmonary fibrosis.
      ,
      • Ebihara T.
      • Venkatesan N.
      • Tanaka R.
      • Ludwig M.S.
      Changes in extracellular matrix and tissue viscoelasticity in bleomycin-induced lung fibrosis. Temporal aspects.
      ,
      • Kolb M.
      • Margetts P.J.
      • Sime P.J.
      • Gauldie J.
      Proteoglycans decorin and biglycan differentially modulate TGF-beta-mediated fibrotic responses in the lung.
      ). Sand et al. (
      • Sand J.M.
      • Larsen L.
      • Hogaboam C.
      • Martinez F.
      • Han M.
      • Rossel Larsen M.
      • et al.
      MMP mediated degradation of type IV collagen alpha 1 and alpha 3 chains reflects basement membrane remodeling in experimental and clinical fibrosis–validation of two novel biomarker assays.
      ) developed ELISA assays to assess the levels of circulating fragments of type IV collagen α1 and α3 chains as indicators of fibrosis and related their elevated levels to liver fibrosis and IPF or chronic obstructive pulmonary disease (COPD), respectively. Teles-Grilo et al. (
      • Teles-Grilo M.L.
      • Leite-Almeida H.
      • Martins dos Santos J.
      • Oliveira C.
      • Boaventura P.
      • Grande N.R.
      Differential expression of collagens type I and type IV in lymphangiogenesis during the angiogenic process associated with bleomycin-induced pulmonary fibrosis in rat.
      ) demonstrated an increased expression of collagen type I and IV around the new pulmonary blood vessels of bleomycin-treated rats where pulmonary fibrosis was induced. The levels of neoepitope PIIINP increased significantly in broncho alveolar lavage fluid of IPF patients compared to controls (
      • Bjermer L.
      • Lundgren R.
      • Hallgren R.
      Hyaluronan and type III procollagen peptide concentrations in bronchoalveolar lavage fluid in idiopathic pulmonary fibrosis.
      ). Tzortzaki et al. (
      • Tzortzaki E.G.
      • Koutsopoulos A.V.
      • Dambaki K.I.
      • Lambiri I.
      • Plataki M.
      • Gordon M.K.
      • et al.
      Active remodeling in idiopathic interstitial pneumonias: evaluation of collagen types XII and XIV.
      ) showed expressions of collagen type XII and XIV in the lung’s fibrosis of IPF patients and overexpression of collagen type I in the fibrotic scar. Leeming et al. (
      • Leeming D.J.
      • Sand J.M.
      • Nielsen M.J.
      • Genovese F.
      • Martinez F.J.
      • Hogaboam C.M.
      • et al.
      Serological investigation of the collagen degradation profile of patients with chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis.
      ) were the first group to investigate the collagen turnover profiles in the serum of patients with lung fibrotic disease. They demonstrated that MMP-mediated degradation products of collagen type I, III, V, and VI (CIM, C3M, C5M, C6M) levels could differentiate between IPF and mild COPD patients and healthy controls. Elevated C4M and C3A (neo-epitope of ADAMTS-4, 5–mediated degradation of type III collagen) levels could be related to COPD.
      Su et al. (
      • Su Y.
      • Gu H.
      • Weng D.
      • Zhou Y.
      • Li Q.
      • Zhang F.
      • et al.
      Association of serum levels of laminin, type IV collagen, procollagen III N-terminal peptide, and hyaluronic acid with the progression of interstitial lung disease.
      ) showed that serum levels of PIIINP and three other ECM molecules (laminin, collagen type IV, and hyaluronic acid) could be used as biomarkers of disease progression from IPF to acute exacerbation of IPF and connective tissue disease–related ILD. Circulating levels of PIIINP were also reported to be higher in patients with progressive pulmonary fibrosis but not in those with stable fibrosis (
      • Low R.B.
      • Giancola M.S.
      • King Jr., T.E.
      • Chapitis J.
      • Vacek P.
      • Davis G.S.
      Serum and bronchoalveolar lavage of N-terminal type III procollagen peptides in idiopathic pulmonary fibrosis.
      ). Kubo et al. (
      • Kubo S.
      • Siebuhr A.S.
      • Bay-Jensen A.C.
      • Juhl P.
      • Karsdal M.A.
      • Satoh Y.
      • et al.
      Correlation between serological biomarkers of extracellular matrix turnover and lung fibrosis and pulmonary artery hypertension in patients with systemic sclerosis.
      ) analyzed nine serological biomarkers of collagen metabolism and organ involvement in 79 patients with systemic sclerosis (SSc) and concluded that increased turnover of collagen seen in patients of SSc may not be derived only from the skin. They reported that SSc patients with ILD or PAH showed increased type VI collagen metabolism as indicated by increased levels of C6M. In addition, ProC3 (a fragment of N-terminal type III collagen) and ProC6 (a fragment of C-terminal type VI a3 collagen) were also higher in SSc patients with PAH. In a prospective cohort study, 11 neoepitopes of MMP-degraded ECM proteins were tested in participants with idiopathic pulmonary fibrosis or idiopathic nonspecific interstitial pneumonia. In patients with progressive idiopathy pulmonary fibrosis, serum levels of C1M, C3A, C3M, C6M, CRPM (C-reactive protein metabolite), and VICM (a fragment of vimentin released by MMP) were significantly higher compared to healthy controls (
      • Jenkins R.G.
      • Simpson J.K.
      • Saini G.
      • Bentley J.H.
      • Russell A.M.
      • Braybrooke R.
      • et al.
      Longitudinal change in collagen degradation biomarkers in idiopathic pulmonary fibrosis: an analysis from the prospective, multicentre PROFILE study.
      ).
      Lung tissues of the patients with IPF showed higher expression of collagen type VI α1 and collagen type VI α3 chains in the fibrotic foci containing a myofibroblasts core and procollagen I (
      • Williams L.M.
      • McCann F.E.
      • Cabrita M.A.
      • Layton T.
      • Cribbs A.
      • Knezevic B.
      • et al.
      Identifying collagen VI as a target of fibrotic diseases regulated by CREBBP/EP300.
      ,
      • Herrera J.
      • Forster C.
      • Pengo T.
      • Montero A.
      • Swift J.
      • Schwartz M.A.
      • et al.
      Registration of the extracellular matrix components constituting the fibroblastic focus in idiopathic pulmonary fibrosis.
      ). In addition, collagen type VI also interacts with ECM and cell surface proteins and forms a filamentous mesh around collagen I, II, III, and IV fibers (
      • Godwin A.R.F.
      • Starborg T.
      • Sherratt M.J.
      • Roseman A.M.
      • Baldock C.
      Defining the hierarchical organisation of collagen VI microfibrils at nanometre to micrometre length scales.
      ). It was suggested that collagen type VI may also have a regulatory role in the early events of pulmonary fibrosis (
      • Specks U.
      • Nerlich A.
      • Colby T.V.
      • Wiest I.
      • Timpl R.
      Increased expression of type VI collagen in lung fibrosis.
      ).

      Galectin-3 as a biomarker in pulmonary fibrosis

      Calvier et al. demonstrated a direct correlation between the onset of vascular hypertrophy, inflammation, and fibrosis with galectin-3 levels (
      • Calvier L.
      • Miana M.
      • Reboul P.
      • Cachofeiro V.
      • Martinez-Martinez E.
      • de Boer R.A.
      • et al.
      Galectin-3 mediates aldosterone-induced vascular fibrosis.
      ). Galectin-3 affects STAT 3 and MMP 9 signaling pathways in response to TGF-β induction and mediates vascular fibrosis (
      • Wang X.
      • Wang Y.
      • Zhang J.
      • Guan X.
      • Chen M.
      • Li Y.
      • et al.
      Galectin-3 contributes to vascular fibrosis in monocrotaline-induced pulmonary arterial hypertension rat model.
      ). In a mouse model, TGF-β and bleomycin-induced lung fibrosis was blocked by TD139, a galectin-3 small molecule inhibitor with an affinity for carbohydrate-binding domain (
      • Mackinnon A.C.
      • Gibbons M.A.
      • Farnworth S.L.
      • Leffler H.
      • Nilsson U.J.
      • Delaine T.
      • et al.
      Regulation of transforming growth factor-beta1-driven lung fibrosis by galectin-3.
      ) via inhibiting β-catenin nuclear translocation. Similar effects were replicated in galectin-3 knockout mice (
      • Mackinnon A.C.
      • Gibbons M.A.
      • Farnworth S.L.
      • Leffler H.
      • Nilsson U.J.
      • Delaine T.
      • et al.
      Regulation of transforming growth factor-beta1-driven lung fibrosis by galectin-3.
      ).
      In patients with PAH, serum galectin-3 levels were higher than the base levels (
      • Fenster B.E.
      • Lasalvia L.
      • Schroeder J.D.
      • Smyser J.
      • Silveira L.J.
      • Buckner J.K.
      • et al.
      Galectin-3 levels are associated with right ventricular functional and morphologic changes in pulmonary arterial hypertension.
      ) while other studies showed that serum galectin-3 could be a biomarker of the severity of PAH (
      • Calvier L.
      • Legchenko E.
      • Grimm L.
      • Sallmon H.
      • Hatch A.
      • Plouffe B.D.
      • et al.
      Galectin-3 and aldosterone as potential tandem biomarkers in pulmonary arterial hypertension.
      ,
      • Mazurek J.A.
      • Horne B.D.
      • Saeed W.
      • Sardar M.R.
      • Zolty R.
      Galectin-3 levels are elevated and predictive of mortality in pulmonary hypertension.
      ). Feng et al. (
      • Feng W.
      • Wu X.
      • Li S.
      • Zhai C.
      • Wang J.
      • Shi W.
      • et al.
      Association of serum galectin-3 with the acute exacerbation of chronic obstructive pulmonary disease.
      ) demonstrated an increase in serum galectin-3 levels in patients with acute exacerbation of chronic obstructive pulmonary disease. Furthermore, the levels of circulating galectin-3 were higher in smokers compared to nonsmokers with acute exacerbation of chronic obstructive pulmonary disease. Idiopathic inflammatory myopathy patients with associated ILD showed elevated levels of serum galectin-3 compared to the healthy controls accompanied by increased galectin-3 expression in the inflammatory cells of interstitial fibrosis, myositis, and dermatitis (
      • Watanabe E.
      • Kato K.
      • Gono T.
      • Chiba E.
      • Terai C.
      • Kotake S.
      Serum levels of galectin-3 in idiopathic inflammatory myopathies: a potential biomarker of disease activity.
      ). In a recent study, d’Alessandro et al. (
      • d'Alessandro M.
      • De Vita E.
      • Bergantini L.
      • Mazzei M.A.
      • di Valvasone S.
      • Bonizzoli M.
      • et al.
      Galactin-1, 3 and 9: potential biomarkers in idiopathic pulmonary fibrosis and other interstitial lung diseases.
      ) reported a significant increase in serum galectin-1 and galectin-9 levels in fibrotic ILD patients compared to healthy controls.

      Galectin-3 as a therapeutic target in fibroproliferative diseases

      Galectin-3 secreted by macrophages, epithelial cells, and myofibroblasts regulates fibrosis, resulting in pathophysiological responses that include epithelial mesenchymal transition, apoptosis, activation, and proliferation of myofibroblasts resulting in increased production of ECM. Out of all the galectin family members, galectin-3 has shown the strongest involvement with fibrosis. Several preclinical and clinical studies have been conducted aiming at galectin-3 as an antifibrosis target; however, the results were not consistent.
      Modified citrus pectin (MCP) was first reported as a functional inhibitor of galectin-3 (
      • Inohara H.
      • Raz A.
      Effects of natural complex carbohydrate (citrus pectin) on murine melanoma cell properties related to galectin-3 functions.
      ,
      • Nangia-Makker P.
      • Hogan V.
      • Honjo Y.
      • Baccarini S.
      • Tait L.
      • Bresalier R.
      • et al.
      Inhibition of human cancer cell growth and metastasis in nude mice by oral intake of modified citrus pectin.
      ,
      • Platt D.
      • Raz A.
      Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.
      ). Later, other complex polysaccharides, e.g., belapectin, GCS-100, pectasol, and several small molecule inhibitors GM-CT-01, GR-MD-02, TD139, and GB1211, all focused on carbohydrate-binding domain, became commercially available as fibrosis inhibitors for preclinical and clinical studies. In galectin-3 null mice, hypoxia-induced right ventricle hypertrophy was ameliorated (
      • Hao M.
      • Li M.
      • Li W.
      Galectin-3 inhibition ameliorates hypoxia-induced pulmonary artery hypertension.
      ). Similar results were observed in N-Lac (a nonspecific galectin-3 inhibitor) ---treated mice (
      • Luo H.
      • Liu B.
      • Zhao L.
      • He J.
      • Li T.
      • Zha L.
      • et al.
      Galectin-3 mediates pulmonary vascular remodeling in hypoxia-induced pulmonary arterial hypertension.
      ). Barman et al. demonstrated a direct correlation between the galectin-3 levels and the pulmonary vascular remodeling using galectin-3 KO mice or using GM-CT-01 and GR-MD-02 inhibitors using an animal model of PAH (
      • Barman S.A.
      • Chen F.
      • Li X.
      • Haigh S.
      • Stepp D.W.
      • Kondrikov D.
      • et al.
      Galectin-3 promotes vascular remodeling and contributes to pulmonary hypertension.
      ).
      Inhalation of a small molecule galectin-3 inhibitor TD139, having a strong affinity to the carbohydrate-binding domain, has been shown to reduce galectin-3 expression in the lungs of idiopathic pulmonary fibrosis patients along with decreased circulating levels of platelet-derived growth factor-BB, plasminogen activator inhibitor-1, galectin-3, CCL18, and YKL-40 (
      • Hirani N.
      • MacKinnon A.C.
      • Nicol L.
      • Ford P.
      • Schambye H.
      • Pedersen A.
      • et al.
      Target inhibition of galectin-3 by inhaled TD139 in patients with idiopathic pulmonary fibrosis.
      ). Another small oral molecule GB1211 is under development but has not been tested for fibrosis inhibition. GR-MD-02 attenuated the NASH-related hepatic fibrosis in a thioacetamide-induced mouse model of liver fibrosis and has undergone clinical trials for the treatment of NASH with advanced fibrosis (
      • Traber P.G.
      • Zomer E.
      Therapy of experimental NASH and fibrosis with galectin inhibitors.
      ,
      • Harrison S.A.
      • Marri S.R.
      • Chalasani N.
      • Kohli R.
      • Aronstein W.
      • Thompson G.A.
      • et al.
      Randomised clinical study: GR-MD-02, a galectin-3 inhibitor, vs. placebo in patients having non-alcoholic steatohepatitis with advanced fibrosis.
      ). In phase 2b clinical trials, however, no significant effect on NASH was observed in the patients treated with GR-MD-02 for 1 year compared to the placebo control (
      • Chalasani N.
      • Abdelmalek M.F.
      • Garcia-Tsao G.
      • Vuppalanchi R.
      • Alkhouri N.
      • Rinella M.
      • et al.
      Effects of belapectin, an inhibitor of galectin-3, in patients with nonalcoholic steatohepatitis with cirrhosis and portal hypertension.
      ).
      In a mouse model of dilated cardiomyopathy, galectin-3 was upregulated by ∼40-fold in the heart, accompanied by dilation of cardiac chambers, reduced left ventricular ejection fraction, increased collagen content, and increased fibrosis. While galectin-3 gene knockout reduced these effects, MCP had no effect (
      • Nguyen M.N.
      • Ziemann M.
      • Kiriazis H.
      • Su Y.
      • Thomas Z.
      • Lu Q.
      • et al.
      Galectin-3 deficiency ameliorates fibrosis and remodeling in dilated cardiomyopathy mice with enhanced Mst1 signaling.
      ). In another study, however, MCP ameliorated cardiac dysfunction, reduced collagen deposition, and decreased myocardial injury, and galectin-3 expression in a rat model of heart failure (
      • Xu G.R.
      • Zhang C.
      • Yang H.X.
      • Sun J.H.
      • Zhang Y.
      • Yao T.T.
      • et al.
      Modified citrus pectin ameliorates myocardial fibrosis and inflammation via suppressing galectin-3 and TLR4/MyD88/NF-kappaB signaling pathway.
      ). Belapectin was well tolerated by NASH patients but did not show anti-fibrotic effects in phase II clinical trial (
      • Harrison S.A.
      • Dennis A.
      • Fiore M.M.
      • Kelly M.D.
      • Kelly C.J.
      • Paredes A.H.
      • et al.
      Utility and variability of three non-invasive liver fibrosis imaging modalities to evaluate efficacy of GR-MD-02 in subjects with NASH and bridging fibrosis during a phase-2 randomized clinical trial.
      ). Taken together, these studies imply that targeting just the carbohydrate-binding domain of galectin-3 is probably inadequate, as galectin-3 KO mice showed ameliorated fibrosis. Thus, most likely, both the N and C terminals of galectin-3 should simultaneously be targeted to combat fibrosis.

      Concluding remarks

      Chimeric galectin-3 is a biological marker of active inflammation and advanced disease that could be clinically useful alone or in combination with collagen to serve as marker(s) and therapeutic target(s), based on the fact that collagen fragments are being used as biomarkers for fibrosis and inflammation-related diseases as a noninvasive method to investigate the disease progression. Their abundance and diversity, as well as several synthesis-related and lysis-related neoepitopes of each collagen type make it a very complicated story to analyze. Moreover, as the neoepitopes are detected in serum, it is hard to predict the site of fibrosis unless other markers and symptoms of the disease are investigated. For example, serum levels of PIIINP are enhanced in progression of the liver, heart, and lung disease, while some other neoepitopes are specific for a particular organ, e.g., C6M and C3M are specific for liver fibrosis and PINP is specific for lung fibrosis (
      • Ricard-Blum S.
      • Baffet G.
      • Theret N.
      Molecular and tissue alterations of collagens in fibrosis.
      ). A detailed fingerprinting of various epitopes is required to be able to predict accurately the course of disease progression. Moreover, for accurate measurement of these markers, a specific antibody is crucial. Their levels can also be influenced by cellular uptake as some of the neoepitopes work as signaling molecules for cell surface receptors, e.g., integrin receptors (reviewed by (
      • Karsdal M.A.
      • Daniels S.J.
      • Holm Nielsen S.
      • Bager C.
      • Rasmussen D.G.K.
      • Loomba R.
      • et al.
      Collagen biology and non-invasive biomarkers of liver fibrosis.
      )).
      Galectin-3 on the other hand belongs to a small family. Specific antibodies are present for different members of the family. Moreover, galectin-3, galectin-1, and galectin-9 are the only galectins related to fibrosis, with galectin-3 being the most thoroughly investigated. Galectin-3 is of particular interest because it can be used as a biomarker as well as therapeutic target for fibrosis as it is one of the earlier proteins released during neutrophil activation. The secreted protein is cleaved by MMPs in the same manner as collagens, and its cleavage has been proposed to be used as a diagnostic marker of MMP activity (
      • Nangia-Makker P.
      • Raz T.
      • Tait L.
      • Hogan V.
      • Fridman R.
      • Raz A.
      Galectin-3 cleavage: a novel surrogate marker for matrix metalloproteinase activity in growing breast cancers.
      ). A comparison of the 3-dimensional structure of galectin-1 and galectin-3 full-length and cleaved forms has been shown in Fig. 3. Cleaved galectin-3 retains some part of the N-terminal domain, making it different from galectin-1, which is made up only of the CRD. Specific antibodies are able to distinguish between the full-length and cleaved galectin-3 (
      • Nangia-Makker P.
      • Raz T.
      • Tait L.
      • Hogan V.
      • Fridman R.
      • Raz A.
      Galectin-3 cleavage: a novel surrogate marker for matrix metalloproteinase activity in growing breast cancers.
      ).
      However, targeting galectin-3 has not been as successful as antifibrosis treatment, compared to the studies in KO mice. This could be because all the inhibitors used so far are designed specifically to target CRD. As presented in Table 1, both N-terminal and C-terminal domains of galectin-3 play a significant role in ligand binding. N-terminal domain is important for full biological activity of galectin-3. It facilitates proper folding of the protein, its multivalency, secretion, and its carbohydrate-binding properties. Flores-Ibarra et al. (
      • Flores-Ibarra A.
      • Vertesy S.
      • Medrano F.J.
      • Gabius H.J.
      • Romero A.
      Crystallization of a human galectin-3 variant with two ordered segments in the shortened N-terminal tail.
      ) reported formation of hairpin by the amino acids spanning Tyr101 in the N-terminal to Leu 114 in CRD. Miller et al. demonstrated that binding of polysaccharide rhamnogalacturonan to galectin-3 utilized two epitopes within the carbohydrate-binding domain, and one novel epitope within the first 40 amino acids of the N-terminal domain (
      • Miller M.C.
      • Zheng Y.
      • Yan J.
      • Zhou Y.
      • Tai G.
      • Mayo K.H.
      Novel polysaccharide binding to the N-terminal tail of galectin-3 is likely modulated by proline isomerization.
      ). To neutralize the microbicidal properties of galectin-3, protozoan parasites Trypanosoma cruzi and Leishmania major have developed molecular mechanisms to proteolytically cleave galecin-3 at its N terminus. The cleaved galectin-3 retained the carbohydrate-binding capacity but failed to induce the immune response (
      • Pineda M.
      • Corvo L.
      • Callejas-Hernandez F.
      • Fresno M.
      • Bonay P.
      Trypanosoma cruzi cleaves galectin-3 N-terminal domain to suppress its innate microbicidal activity.
      ,
      • Pelletier I.
      • Sato S.
      Specific recognition and cleavage of galectin-3 by Leishmania major through species-specific polygalactose epitope.
      ). In a recent report, Zhao et al. (
      • Zhao Z.
      • Xu X.
      • Cheng H.
      • Miller M.C.
      • He Z.
      • Gu H.
      • et al.
      Galectin-3 N-terminal tail prolines modulate cell activity and glycan-mediated oligomerization/phase separation.
      ) reported that replacing the prolines in the N-terminal domain impaired all the classical cellular functions attributed to galectin-3. Mauris et al. demonstrated the requirement of a full-length protein for interaction with and clustering of CD147, an MMP-9 inducer in migrating epithelia (
      • Mauris J.
      • Woodward A.M.
      • Cao Z.
      • Panjwani N.
      • Argueso P.
      Molecular basis for MMP9 induction and disruption of epithelial cell-cell contacts by galectin-3.
      ). N-terminal domain of galectin-3 secreted by T cells upon T cell receptor engagement interacts with the proline-rich region of ALG-2–interacting protein X (Alix) in HIV infected cells facilitating HIV-1 budding (
      • Wang S.F.
      • Tsao C.H.
      • Lin Y.T.
      • Hsu D.K.
      • Chiang M.L.
      • Lo C.H.
      • et al.
      Galectin-3 promotes HIV-1 budding via association with Alix and Gag p6.
      ). Bocker et al. found that Δ1-62 and Δ1-116 showed a 3- to 6-fold increased binding efficiency to asialofetuin compared to native galectin-3 when tagged with SNAP (
      • Bocker S.
      • Elling L.
      Binding characteristics of galectin-3 fusion proteins.
      ). Although galectin-3 enhances neutrophil activation by binding to microbial lipopolysaccharides via its carbohydrate recognition domain, N-terminal domain is also required, indicating dependence upon multivalency of galectin-3 (
      • Fermino M.L.
      • Polli C.D.
      • Toledo K.A.
      • Liu F.T.
      • Hsu D.K.
      • Roque-Barreira M.C.
      • et al.
      LPS-induced galectin-3 oligomerization results in enhancement of neutrophil activation.
      ,
      • Lo T.H.
      • Chen H.L.
      • Yao C.I.
      • Weng I.C.
      • Li C.S.
      • Huang C.C.
      • et al.
      Galectin-3 promotes noncanonical inflammasome activation through intracellular binding to lipopolysaccharide glycans.
      ).
      Considering the above, it may be worthwhile to target both N-terminal and C-terminal domains of galectin-3 to control fibrosis by small molecule inhibitors and/or galectin-3 domains-specific antibodies. DX-52-1, a semisynthetic derivative of quinocarmycin, and HUK-921, a complex synthetic molecule related to naphthyridinomycin family, are two compounds that were reported to bind galectin-3 outside of its carbohydrate domain (
      • Kahsai A.W.
      • Cui J.
      • Kaniskan H.U.
      • Garner P.P.
      • Fenteany G.
      Analogs of tetrahydroisoquinoline natural products that inhibit cell migration and target galectin-3 outside of its carbohydrate-binding site.
      ) and exhibited antimigration and antiproliferation effects on cells and showed no competition with the agonist lactose. In addition, several noncarbohydrate small molecules have been designed and tested (reviewed by (
      • Sethi A.
      • Sanam S.
      • Alvala M.
      Non-carbohydrate strategies to inhibit lectin proteins with special emphasis on galectins.
      )) in an attempt to obtain more maintainable, reproducible, and effective galectin-3 inhibition, however, with limited success. The potential for galectin-3 as a therapeutic target in fibrosis remains a challenge together with the need to further unveil the molecular mechanism that regulates MMPs activities in the circulation. It is expected that due to the deleterious effects of fibrosis on organs’ functions, a new class of drugs/antibodies selectively and explicitly directed against the intact and cleaved galectin-3 will be available as a novel therapeutic modality, not too far away in the future.

      Conflict of interests

      The authors declare that they have no conflict of interest with the contents of this article.

      Author contributions

      P. N.-M. and A. R. conceptualization; P. N.-M. and A. R. investigation; P. N.-M. writing-original draft; P. N.-M., V. H., and A. R. writing-reviewing and editing; V. B. visualization and analysis of galectin-1 and -3 structures.

      Funding and additional information

      This work was supported by the Paul Zuckerman Endowment (to A. R.) and by the NCI/ NIH Cancer Center Support Grant ( CA-22453 ).

      References

        • Genovese F.
        • Karsdal M.A.
        Protein degradation fragments as diagnostic and prognostic biomarkers of connective tissue diseases: understanding the extracellular matrix message and implication for current and future serological biomarkers.
        Expert Rev. Proteomics. 2016; 13: 213-225
        • Nikolic-Paterson D.J.
        • Main I.W.
        • Tesch G.H.
        • Lan H.Y.
        • Atkins R.C.
        Interleukin-1 in renal fibrosis.
        Kidney Int. Suppl. 1996; 54: S88-90
        • O'Reilly S.
        • Ciechomska M.
        • Cant R.
        • Hugle T.
        • van Laar J.M.
        Interleukin-6, its role in fibrosing conditions.
        Cytokine Growth Factor Rev. 2012; 23: 99-107
        • Wu N.
        • Meng F.
        • Invernizzi P.
        • Bernuzzi F.
        • Venter J.
        • Standeford H.
        • et al.
        The secretin/secretin receptor axis modulates liver fibrosis through changes in transforming growth factor-beta1 biliary secretion in mice.
        Hepatology. 2016; 64: 865-879
        • Walton K.L.
        • Johnson K.E.
        • Harrison C.A.
        Targeting TGF-beta mediated SMAD signaling for the prevention of fibrosis.
        Front. Pharmacol. 2017; 8: 461
        • Wynn T.A.
        Fibrotic disease and the T(H)1/T(H)2 paradigm.
        Nat. Rev. Immunol. 2004; 4: 583-594
        • Mak K.M.
        • Mei R.
        Basement membrane type IV collagen and laminin: an overview of their biology and value as fibrosis biomarkers of liver disease.
        Anat. Rec. (Hoboken). 2017; 300: 1371-1390
        • Vracko R.
        Basal lamina scaffold-anatomy and significance for maintenance of orderly tissue structure.
        Am. J. Pathol. 1974; 77: 314-346
        • Karsdal M.A.
        • Daniels S.J.
        • Holm Nielsen S.
        • Bager C.
        • Rasmussen D.G.K.
        • Loomba R.
        • et al.
        Collagen biology and non-invasive biomarkers of liver fibrosis.
        Liver Int. 2020; 40: 736-750
        • Ricard-Blum S.
        The collagen family.
        Cold Spring Harb. Perspect. Biol. 2011; 3: a004978
        • Raz A.
        • Pazerini G.
        • Carmi P.
        Identification of the metastasis-associated, galactoside-binding lectin as a chimeric gene product with homology to an IgE-binding protein.
        Cancer Res. 1989; 49: 3489-3493
        • Raz A.
        • Carmi P.
        • Raz T.
        • Hogan V.
        • Mohamed A.
        • Wolman S.R.
        Molecular cloning and chromosomal mapping of a human galactoside-binding protein.
        Cancer Res. 1991; 51: 2173-2178
        • Gong H.C.
        • Honjo Y.
        • Nangia-Makker P.
        • Hogan V.
        • Mazurak N.
        • Bresalier R.S.
        • et al.
        The NH2 terminus of galectin-3 governs cellular compartmentalization and functions in cancer cells.
        Cancer Res. 1999; 59: 6239-6245
        • Ochieng J.
        • Fridman R.
        • Nangia-Makker P.
        • Kleiner D.E.
        • Liotta L.A.
        • Stetler-Stevenson W.G.
        • et al.
        Galectin-3 is a novel substrate for human matrix metalloproteinases-2 and -9.
        Biochemistry. 1994; 33: 14109-14114
        • Nangia-Makker P.
        • Raz T.
        • Tait L.
        • Hogan V.
        • Fridman R.
        • Raz A.
        Galectin-3 cleavage: a novel surrogate marker for matrix metalloproteinase activity in growing breast cancers.
        Cancer Res. 2007; 67: 11760-11768
        • Balan V.
        • Nangia-Makker P.
        • Schwartz A.G.
        • Jung Y.S.
        • Tait L.
        • Hogan V.
        • et al.
        Racial disparity in breast cancer and functional germ line mutation in galectin-3 (rs4644): a pilot study.
        Cancer Res. 2008; 68: 10045-10050
        • Ochieng J.
        • Green B.
        • Evans S.
        • James O.
        • Warfield P.
        Modulation of the biological functions of galectin-3 by matrix metalloproteinases.
        Biochim. Biophys. Acta. 1998; 1379: 97-106
        • Lin Y.H.
        • Qiu D.C.
        • Chang W.H.
        • Yeh Y.Q.
        • Jeng U.S.
        • Liu F.T.
        • et al.
        The intrinsically disordered N-terminal domain of galectin-3 dynamically mediates multisite self-association of the protein through fuzzy interactions.
        J. Biol. Chem. 2017; 292: 17845-17856
        • Demetriou M.
        • Granovsky M.
        • Quaggin S.
        • Dennis J.W.
        Negative regulation of T-cell activation and autoimmunity by Mgat5 N-glycosylation.
        Nature. 2001; 409: 733-739
        • Pugliese G.
        • Iacobini C.
        • Pesce C.M.
        • Menini S.
        Galectin-3: an emerging all-out player in metabolic disorders and their complications.
        Glycobiology. 2015; 25: 136-150
        • Hara A.
        • Niwa M.
        • Noguchi K.
        • Kanayama T.
        • Niwa A.
        • Matsuo M.
        • et al.
        Galectin-3 as a next-generation biomarker for detecting early stage of various diseases.
        Biomolecules. 2020; 10: 389
        • Miah A.
        • S P.
        • Tongue P.
        • Roach K.
        • Bradding P.
        • Gooptu B.
        Ex vivo studies of the gal-3-fibrosome hypothesis in IPF and non-fibrotic control lung tissue and myofibroblasts..
        Thorax. 2019; 74: A57
        • Liu F.T.
        • Hsu D.K.
        The role of galectin-3 in promotion of the inflammatory response.
        Drug News Perspect. 2007; 20: 455-460
        • Fulton D.J.R.
        • Li X.
        • Bordan Z.
        • Wang Y.
        • Mahboubi K.
        • Rudic R.D.
        • et al.
        Galectin-3: a harbinger of reactive oxygen species, fibrosis, and inflammation in pulmonary arterial hypertension.
        Antioxid. Redox Signal. 2019; 31: 1053-1069
        • MacKinnon A.C.
        • Farnworth S.L.
        • Hodkinson P.S.
        • Henderson N.C.
        • Atkinson K.M.
        • Leffler H.
        • et al.
        Regulation of alternative macrophage activation by galectin-3.
        J. Immunol. 2008; 180: 2650-2658
        • Mackinnon A.C.
        • Gibbons M.A.
        • Farnworth S.L.
        • Leffler H.
        • Nilsson U.J.
        • Delaine T.
        • et al.
        Regulation of transforming growth factor-beta1-driven lung fibrosis by galectin-3.
        Am. J. Respir. Crit. Care Med. 2012; 185: 537-546
        • Sato S.
        • Ouellet N.
        • Pelletier I.
        • Simard M.
        • Rancourt A.
        • Bergeron M.G.
        Role of galectin-3 as an adhesion molecule for neutrophil extravasation during streptococcal pneumonia.
        J. Immunol. 2002; 168: 1813-1822
        • Dong S.
        • Hughes R.C.
        Macrophage surface glycoproteins binding to galectin-3 (Mac-2-antigen).
        Glycoconj J. 1997; 14: 267-274
        • Slack R.J.
        • Mills R.
        • Mackinnon A.C.
        The therapeutic potential of galectin-3 inhibition in fibrotic disease.
        Int. J. Biochem. Cell Biol. 2021; 130: 105881
        • Martinez-Hernandez A.
        • Martinez J.
        The role of capillarization in hepatic failure: studies in carbon tetrachloride-induced cirrhosis.
        Hepatology. 1991; 14: 864-874
        • Chen W.
        • Rock J.B.
        • Yearsley M.M.
        • Ferrell L.D.
        • Frankel W.L.
        Different collagen types show distinct rates of increase from early to late stages of hepatitis C-related liver fibrosis.
        Hum. Pathol. 2014; 45: 160-165
        • Rojkind M.
        • Ponce-Noyola P.
        The extracellular matrix of the liver.
        Coll. Relat. Res. 1982; 2: 151-175
        • Ueno T.
        • Inuzuka S.
        • Torimura T.
        • Oohira H.
        • Ko H.
        • Obata K.
        • et al.
        Significance of serum type-IV collagen levels in various liver diseases. Measurement with a one-step sandwich enzyme immunoassay using monoclonal antibodies with specificity for pepsin-solubilized type-IV collagen.
        Scand. J. Gastroenterol. 1992; 27: 513-520
        • Hirayama C.
        • Suzuki H.
        • Takada A.
        • Fujisawa K.
        • Tanikawa K.
        • Igarashi S.
        Serum type IV collagen in various liver diseases in comparison with serum 7S collagen, laminin, and type III procollagen peptide.
        J. Gastroenterol. 1996; 31: 242-248
        • Murawaki Y.
        • Ikuta Y.
        • Koda M.
        • Yamada S.
        • Kawasaki H.
        Comparison of serum 7S fragment of type IV collagen and serum central triple-helix of type IV collagen for assessment of liver fibrosis in patients with chronic viral liver disease.
        J. Hepatol. 1996; 24: 148-154
        • Sakugawa H.
        • Nakayoshi T.
        • Kobashigawa K.
        • Yamashiro T.
        • Maeshiro T.
        • Miyagi S.
        • et al.
        Clinical usefulness of biochemical markers of liver fibrosis in patients with nonalcoholic fatty liver disease.
        World J. Gastroenterol. 2005; 11: 255-259
        • Yoneda M.
        • Mawatari H.
        • Fujita K.
        • Yonemitsu K.
        • Kato S.
        • Takahashi H.
        • et al.
        Type IV collagen 7s domain is an independent clinical marker of the severity of fibrosis in patients with nonalcoholic steatohepatitis before the cirrhotic stage.
        J. Gastroenterol. 2007; 42: 375-381
        • Hayasaka A.
        • Schuppan D.
        • Ohnishi K.
        • Okuda K.
        • Hahn E.G.
        Serum concentrations of the carboxyterminal cross-linking domain of procollagen type IV (NC1) and the aminoterminal propeptide of procollagen type III (PIIIP) in chronic liver disease.
        J. Hepatol. 1990; 10: 17-22
        • Babbs C.
        • Haboubi N.Y.
        • Mellor J.M.
        • Smith A.
        • Rowan B.P.
        • Warnes T.W.
        Endothelial cell transformation in primary biliary cirrhosis: a morphological and biochemical study.
        Hepatology. 1990; 11: 723-729
        • Siddiqui M.S.
        • Yamada G.
        • Vuppalanchi R.
        • Van Natta M.
        • Loomba R.
        • Guy C.
        • et al.
        Diagnostic accuracy of noninvasive fibrosis models to detect change in fibrosis stage.
        Clin. Gastroenterol. Hepatol. 2019; 17: 1877-1885.e1875
        • Peleg N.
        • Sneh Arbib O.
        • Issachar A.
        • Cohen-Naftaly M.
        • Braun M.
        • Shlomai A.
        Noninvasive scoring systems predict hepatic and extra-hepatic cancers in patients with nonalcoholic fatty liver disease.
        PLoS One. 2018; 13: e0202393
        • Nielsen M.J.
        • Kazankov K.
        • Leeming D.J.
        • Karsdal M.A.
        • Krag A.
        • Barrera F.
        • et al.
        Markers of collagen remodeling detect clinically significant fibrosis in chronic hepatitis C patients.
        PLoS One. 2015; 10: e0137302
        • Trinchet J.C.
        • Hartmann D.J.
        • Pateron D.
        • Munz-Gotheil C.
        • Callard P.
        • Ville G.
        • et al.
        Serum type I collagen and N-terminal peptide of type III procollagen in patients with alcoholic liver disease: relationship to liver histology.
        Alcohol. Clin. Exp. Res. 1992; 16: 342-346
        • Rosenberg W.M.
        • Voelker M.
        • Thiel R.
        • Becka M.
        • Burt A.
        • Schuppan D.
        • et al.
        Serum markers detect the presence of liver fibrosis: a cohort study.
        Gastroenterology. 2004; 127: 1704-1713
        • Nielsen M.J.
        • Nedergaard A.F.
        • Sun S.
        • Veidal S.S.
        • Larsen L.
        • Zheng Q.
        • et al.
        The neo-epitope specific PRO-C3 ELISA measures true formation of type III collagen associated with liver and muscle parameters.
        Am. J. Transl. Res. 2013; 5: 303-315
        • Iacobini C.
        • Menini S.
        • Ricci C.
        • Blasetti Fantauzzi C.
        • Scipioni A.
        • Salvi L.
        • et al.
        Galectin-3 ablation protects mice from diet-induced NASH: a major scavenging role for galectin-3 in liver.
        J. Hepatol. 2011; 54: 975-983
        • Negre-Salvayre A.
        • Coatrieux C.
        • Ingueneau C.
        • Salvayre R.
        Advanced lipid peroxidation end products in oxidative damage to proteins. Potential role in diseases and therapeutic prospects for the inhibitors.
        Br. J. Pharmacol. 2008; 153: 6-20
        • Butscheid M.
        • Hauptvogel P.
        • Fritz P.
        • Klotz U.
        • Alscher D.M.
        Hepatic expression of galectin-3 and receptor for advanced glycation end products in patients with liver disease.
        J. Clin. Pathol. 2007; 60: 415-418
        • Hinderer S.
        • Schenke-Layland K.
        Cardiac fibrosis - a short review of causes and therapeutic strategies.
        Adv. Drug Deliv. Rev. 2019; 146: 77-82
        • Eghbali M.
        • Czaja M.J.
        • Zeydel M.
        • Weiner F.R.
        • Zern M.A.
        • Seifter S.
        • et al.
        Collagen chain mRNAs in isolated heart cells from young and adult rats.
        J. Mol. Cell Cardiol. 1988; 20: 267-276
        • Eghbali M.
        • Blumenfeld O.O.
        • Seifter S.
        • Buttrick P.M.
        • Leinwand L.A.
        • Robinson T.F.
        • et al.
        Localization of types I, III and IV collagen mRNAs in rat heart cells by in situ hybridization.
        J. Mol. Cell Cardiol. 1989; 21: 103-113
        • Engvall E.
        • Hessle H.
        • Klier G.
        Molecular assembly, secretion, and matrix deposition of type VI collagen.
        J. Cell Biol. 1986; 102: 703-710
        • Yang C.
        • Qiao S.
        • Song Y.
        • Liu Y.
        • Tang Y.
        • Deng L.
        • et al.
        Procollagen type I carboxy-terminal propeptide (PICP) and MMP-2 are potential biomarkers of myocardial fibrosis in patients with hypertrophic cardiomyopathy.
        Cardiovasc. Pathol. 2019; 43: 107150
        • Ferreira J.P.
        • Rossignol P.
        • Pizard A.
        • Machu J.L.
        • Collier T.
        • Girerd N.
        • et al.
        Potential spironolactone effects on collagen metabolism biomarkers in patients with uncontrolled blood pressure.
        Heart. 2019; 105: 307-314
        • Adamcova M.
        • Baka T.
        • Dolezelova E.
        • Aziriova S.
        • Krajcirovicova K.
        • Karesova I.
        • et al.
        Relations between markers of cardiac remodelling and left ventricular collagen in an isoproterenol-induced heart damage model.
        J. Physiol. Pharmacol. 2019; 70https://doi.org/10.26402/jpp.2019.1.08
        • Ruiz-Ruiz F.J.
        • Ruiz-Laiglesia F.J.
        • Samperiz-Legarre P.
        • Lasierra-Diaz P.
        • Flamarique-Pascual A.
        • Morales-Rull J.L.
        • et al.
        Propeptide of procollagen type I (PIP) and outcomes in decompensated heart failure.
        Eur. J. Intern. Med. 2007; 18: 129-134
        • Colige A.
        • Vandenberghe I.
        • Thiry M.
        • Lambert C.A.
        • Van Beeumen J.
        • Li S.W.
        • et al.
        Cloning and characterization of ADAMTS-14, a novel ADAMTS displaying high homology with ADAMTS-2 and ADAMTS-3.
        J. Biol. Chem. 2002; 277: 5756-5766
        • Zile M.R.
        • O'Meara E.
        • Claggett B.
        • Prescott M.F.
        • Solomon S.D.
        • Swedberg K.
        • et al.
        Effects of sacubitril/valsartan on biomarkers of extracellular matrix regulation in patients with HFrEF.
        J. Am. Coll. Cardiol. 2019; 73: 795-806
        • Zhang B.
        • Li X.
        • Chen C.
        • Jiang W.
        • Lu D.
        • Liu Q.
        • et al.
        Renal denervation effects on myocardial fibrosis and ventricular arrhythmias in rats with ischemic cardiomyopathy.
        Cell Physiol. Biochem. 2018; 46: 2471-2479
        • Klappacher G.
        • Franzen P.
        • Haab D.
        • Mehrabi M.
        • Binder M.
        • Plesch K.
        • et al.
        Measuring extracellular matrix turnover in the serum of patients with idiopathic or ischemic dilated cardiomyopathy and impact on diagnosis and prognosis.
        Am. J. Cardiol. 1995; 75: 913-918
        • Ding Y.
        • Wang Y.
        • Zhang W.
        • Jia Q.
        • Wang X.
        • Li Y.
        • et al.
        Roles of biomarkers in myocardial fibrosis.
        Aging Dis. 2020; 11: 1157-1174
        • Lombardi R.
        • Betocchi S.
        • Losi M.A.
        • Tocchetti C.G.
        • Aversa M.
        • Miranda M.
        • et al.
        Myocardial collagen turnover in hypertrophic cardiomyopathy.
        Circulation. 2003; 108: 1455-1460
        • Morine K.J.
        • Paruchuri V.
        • Qiao X.
        • Mohammad N.
        • McGraw A.
        • Yunis A.
        • et al.
        Circulating multimarker profile of patients with symptomatic heart failure supports enhanced fibrotic degradation and decreased angiogenesis.
        Biomarkers. 2016; 21: 91-97
        • Kallergis E.M.
        • Manios E.G.
        • Kanoupakis E.M.
        • Mavrakis H.E.
        • Arfanakis D.A.
        • Maliaraki N.E.
        • et al.
        Extracellular matrix alterations in patients with paroxysmal and persistent atrial fibrillation: biochemical assessment of collagen type-I turnover.
        J. Am. Coll. Cardiol. 2008; 52: 211-215
        • Manhenke C.
        • Orn S.
        • Squire I.
        • Radauceanu A.
        • Alla F.
        • Zannad F.
        • et al.
        The prognostic value of circulating markers of collagen turnover after acute myocardial infarction.
        Int. J. Cardiol. 2011; 150: 277-282
        • Nagao K.
        • Inada T.
        • Tamura A.
        • Kajitani K.
        • Shimamura K.
        • Yukawa H.
        • et al.
        Circulating markers of collagen types I, III, and IV in patients with dilated cardiomyopathy: relationships with myocardial collagen expression.
        ESC Heart Fail. 2018; 5: 1044-1051
        • Chow S.L.
        • Maisel A.S.
        • Anand I.
        • Bozkurt B.
        • de Boer R.A.
        • Felker G.M.
        • et al.
        Role of biomarkers for the prevention, assessment, and management of heart failure: a scientific statement from the American heart association.
        Circulation. 2017; 135: e1054-e1091
        • Meijers W.C.
        • Januzzi J.L.
        • deFilippi C.
        • Adourian A.S.
        • Shah S.J.
        • van Veldhuisen D.J.
        • et al.
        Elevated plasma galectin-3 is associated with near-term rehospitalization in heart failure: a pooled analysis of 3 clinical trials.
        Am. Heart J. 2014; 167: 853-860.e854
        • Imran T.F.
        • Shin H.J.
        • Mathenge N.
        • Wang F.
        • Kim B.
        • Joseph J.
        • et al.
        Meta-analysis of the usefulness of plasma galectin-3 to predict the risk of mortality in patients with heart failure and in the general population.
        Am. J. Cardiol. 2017; 119: 57-64
        • Chen H.
        • Chen C.
        • Fang J.
        • Wang R.
        • Nie W.
        Circulating galectin-3 on admission and prognosis in acute heart failure patients: a meta-analysis.
        Heart Fail. Rev. 2020; 25: 331-341
        • Felker G.M.
        • Fiuzat M.
        • Shaw L.K.
        • Clare R.
        • Whellan D.J.
        • Bettari L.
        • et al.
        Galectin-3 in ambulatory patients with heart failure: results from the HF-action study.
        Circ. Heart Fail. 2012; 5: 72-78
        • Demissei B.G.
        • Cotter G.
        • Prescott M.F.
        • Felker G.M.
        • Filippatos G.
        • Greenberg B.H.
        • et al.
        A multimarker multi-time point-based risk stratification strategy in acute heart failure: results from the RELAX-AHF trial.
        Eur. J. Heart Fail. 2017; 19: 1001-1010
        • Tummalapalli S.L.
        • Zelnick L.R.
        • Andersen A.H.
        • Christenson R.H.
        • deFilippi C.R.
        • Deo R.
        • et al.
        Association of cardiac biomarkers with the Kansas city cardiomyopathy questionnaire in patients with chronic kidney disease without heart failure.
        J. Am. Heart Assoc. 2020; 9: e014385
        • Blanda V.
        • Bracale U.M.
        • Di Taranto M.D.
        • Fortunato G.
        Galectin-3 in cardiovascular diseases.
        Int. J. Mol. Sci. 2020; 21: 9232
        • Falcone C.
        • Lucibello S.
        • Mazzucchelli I.
        • Bozzini S.
        • D'Angelo A.
        • Schirinzi S.
        • et al.
        Galectin-3 plasma levels and coronary artery disease: a new possible biomarker of acute coronary syndrome.
        Int. J. Immunopathol. Pharmacol. 2011; 24: 905-913
        • Oyenuga A.
        • Folsom A.R.
        • Fashanu O.
        • Aguilar D.
        • Ballantyne C.M.
        Plasma galectin-3 and sonographic measures of carotid atherosclerosis in the atherosclerosis risk in communities study.
        Angiology. 2019; 70: 47-55
        • Ciaccio M.
        • Agnello L.
        • Bracale U.M.
        • Taranto M.
        • Ciaccio M.
        • Bracale U.M.
        • et al.
        Galectin-3 and Lp(a) plasma concentrations and advanced carotid atherosclerotic plaques: correlation with plaque presence and features.
        Biochim. Cli. 2019; 43: 289-295
        • Gao Z.
        • Liu Z.
        • Wang R.
        • Zheng Y.
        • Li H.
        • Yang L.
        Galectin-3 is a potential mediator for atherosclerosis.
        J. Immunol. Res. 2020; 2020: 5284728
        • Sharma U.C.
        • Pokharel S.
        • van Brakel T.J.
        • van Berlo J.H.
        • Cleutjens J.P.
        • Schroen B.
        • et al.
        Galectin-3 marks activated macrophages in failure-prone hypertrophied hearts and contributes to cardiac dysfunction.
        Circulation. 2004; 110: 3121-3128
        • Song X.
        • Qian X.
        • Shen M.
        • Jiang R.
        • Wagner M.B.
        • Ding G.
        • et al.
        Protein kinase C promotes cardiac fibrosis and heart failure by modulating galectin-3 expression.
        Biochim. Biophys. Acta. 2015; 1853: 513-521
        • Ferreira J.P.
        • Bauters C.
        • Eschalier R.
        • Lamiral Z.
        • Fay R.
        • Huttin O.
        • et al.
        Echocardiographic diastolic function evolution in patients with an anterior Q-wave myocardial infarction: insights from the REVE-2 study.
        ESC Heart Fail. 2019; 6: 70-79
        • Mortensen M.B.
        • Fuster V.
        • Muntendam P.
        • Mehran R.
        • Baber U.
        • Sartori S.
        • et al.
        Negative risk markers for cardiovascular events in the elderly.
        J. Am. Coll. Cardiol. 2019; 74: 1-11
        • Maiolino G.
        • Rossitto G.
        • Pedon L.
        • Cesari M.
        • Frigo A.C.
        • Azzolini M.
        • et al.
        Galectin-3 predicts long-term cardiovascular death in high-risk patients with coronary artery disease.
        Arterioscler. Thromb. Vasc. Biol. 2015; 35: 725-732
        • Aksan G.
        • Gedikli O.
        • Keskin K.
        • Nar G.
        • Inci S.
        • Yildiz S.S.
        • et al.
        Is galectin-3 a biomarker, a player-or both-in the presence of coronary atherosclerosis?.
        J. Investig. Med. 2016; 64: 764-770
        • Swiecki P.
        • Sawicki R.
        • Knapp M.
        • Kaminski K.A.
        • Ptaszynska-Kopczynska K.
        • Sobkowicz B.
        • et al.
        Galectin-3 as the prognostic factor of adverse cardiovascular events in long-term follow up in patients after myocardial infarction-A pilot study.
        J. Clin. Med. 2020; 9: 1640
        • Dong H.
        • Wang Z.H.
        • Zhang N.
        • Liu S.D.
        • Zhao J.J.
        • Liu S.Y.
        Serum Galectin-3 level, not Galectin-1, is associated with the clinical feature and outcome in patients with acute ischemic stroke.
        Oncotarget. 2017; 8: 109752-109761
        • Edsfeldt A.
        • Bengtsson E.
        • Asciutto G.
        • Duner P.
        • Bjorkbacka H.
        • Fredrikson G.N.
        • et al.
        High plasma levels of galectin-3 are associated with increased risk for stroke after carotid endarterectomy.
        Cerebrovasc. Dis. 2016; 41: 199-203
        • Fort-Gallifa I.
        • Hernandez-Aguilera A.
        • Garcia-Heredia A.
        • Cabre N.
        • Luciano-Mateo F.
        • Simo J.M.
        • et al.
        Galectin-3 in peripheral artery disease. Relationships with markers of oxidative stress and inflammation.
        Int. J. Mol. Sci. 2017; 18: 973
        • Bennett G.A.
        • Smith F.J.
        Pulmonary hypertension in rats living under compressed air conditions.
        J. Exp. Med. 1934; 59: 181-193
        • Hance A.J.
        • Crystal R.G.
        The connective tissue of lung.
        Am. Rev. Respir. Dis. 1975; 112: 657-711
        • Seyer J.M.
        • Hutcheson E.T.
        • Kang A.H.
        Collagen polymorphism in idiopathic chronic pulmonary fibrosis.
        J. Clin. Invest. 1976; 57: 1498-1507
        • Bateman E.D.
        • Turner-Warwick M.
        • Adelmann-Grill B.C.
        Immunohistochemical study of collagen types in human foetal lung and fibrotic lung disease.
        Thorax. 1981; 36: 645-653
        • Madri J.A.
        • Furthmayr H.
        Collagen polymorphism in the lung. An immunochemical study of pulmonary fibrosis.
        Hum. Pathol. 1980; 11: 353-366
        • Selman M.
        • Montano M.
        • Ramos C.
        • Chapela R.
        Concentration, biosynthesis and degradation of collagen in idiopathic pulmonary fibrosis.
        Thorax. 1986; 41: 355-359
        • Bensadoun E.S.
        • Burke A.K.
        • Hogg J.C.
        • Roberts C.R.
        Proteoglycan deposition in pulmonary fibrosis.
        Am. J. Respir. Crit. Care Med. 1996; 154: 1819-1828
        • Ebihara T.
        • Venkatesan N.
        • Tanaka R.
        • Ludwig M.S.
        Changes in extracellular matrix and tissue viscoelasticity in bleomycin-induced lung fibrosis. Temporal aspects.
        Am. J. Respir. Crit. Care Med. 2000; 162: 1569-1576
        • Kolb M.
        • Margetts P.J.
        • Sime P.J.
        • Gauldie J.
        Proteoglycans decorin and biglycan differentially modulate TGF-beta-mediated fibrotic responses in the lung.
        Am. J. Physiol. Lung Cell Mol. Physiol. 2001; 280: L1327-1334
        • Sand J.M.
        • Larsen L.
        • Hogaboam C.
        • Martinez F.
        • Han M.
        • Rossel Larsen M.
        • et al.
        MMP mediated degradation of type IV collagen alpha 1 and alpha 3 chains reflects basement membrane remodeling in experimental and clinical fibrosis–validation of two novel biomarker assays.
        PLoS One. 2013; 8: e84934
        • Teles-Grilo M.L.
        • Leite-Almeida H.
        • Martins dos Santos J.
        • Oliveira C.
        • Boaventura P.
        • Grande N.R.
        Differential expression of collagens type I and type IV in lymphangiogenesis during the angiogenic process associated with bleomycin-induced pulmonary fibrosis in rat.
        Lymphology. 2005; 38: 130-135
        • Bjermer L.
        • Lundgren R.
        • Hallgren R.
        Hyaluronan and type III procollagen peptide concentrations in bronchoalveolar lavage fluid in idiopathic pulmonary fibrosis.
        Thorax. 1989; 44: 126-131
        • Tzortzaki E.G.
        • Koutsopoulos A.V.
        • Dambaki K.I.
        • Lambiri I.
        • Plataki M.
        • Gordon M.K.
        • et al.
        Active remodeling in idiopathic interstitial pneumonias: evaluation of collagen types XII and XIV.
        J. Histochem. Cytochem. 2006; 54: 693-700
        • Leeming D.J.
        • Sand J.M.
        • Nielsen M.J.
        • Genovese F.
        • Martinez F.J.
        • Hogaboam C.M.
        • et al.
        Serological investigation of the collagen degradation profile of patients with chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis.
        Biomark Insights. 2012; 7: 119-126
        • Su Y.
        • Gu H.
        • Weng D.
        • Zhou Y.
        • Li Q.
        • Zhang F.
        • et al.
        Association of serum levels of laminin, type IV collagen, procollagen III N-terminal peptide, and hyaluronic acid with the progression of interstitial lung disease.
        Medicine (Baltimore). 2017; 96: e6617
        • Low R.B.
        • Giancola M.S.
        • King Jr., T.E.
        • Chapitis J.
        • Vacek P.
        • Davis G.S.
        Serum and bronchoalveolar lavage of N-terminal type III procollagen peptides in idiopathic pulmonary fibrosis.
        Am. Rev. Respir. Dis. 1992; 146: 701-706
        • Kubo S.
        • Siebuhr A.S.
        • Bay-Jensen A.C.
        • Juhl P.
        • Karsdal M.A.
        • Satoh Y.
        • et al.
        Correlation between serological biomarkers of extracellular matrix turnover and lung fibrosis and pulmonary artery hypertension in patients with systemic sclerosis.
        Int. J. Rheum. Dis. 2020; 23: 532-539
        • Jenkins R.G.
        • Simpson J.K.
        • Saini G.
        • Bentley J.H.
        • Russell A.M.
        • Braybrooke R.
        • et al.
        Longitudinal change in collagen degradation biomarkers in idiopathic pulmonary fibrosis: an analysis from the prospective, multicentre PROFILE study.
        Lancet Respir. Med. 2015; 3: 462-472
        • Williams L.M.
        • McCann F.E.
        • Cabrita M.A.
        • Layton T.
        • Cribbs A.
        • Knezevic B.
        • et al.
        Identifying collagen VI as a target of fibrotic diseases regulated by CREBBP/EP300.
        Proc. Natl. Acad. Sci. U. S. A. 2020; 117: 20753-20763
        • Herrera J.
        • Forster C.
        • Pengo T.
        • Montero A.
        • Swift J.
        • Schwartz M.A.
        • et al.
        Registration of the extracellular matrix components constituting the fibroblastic focus in idiopathic pulmonary fibrosis.
        JCI Insight. 2019; 4e125185
        • Godwin A.R.F.
        • Starborg T.
        • Sherratt M.J.
        • Roseman A.M.
        • Baldock C.
        Defining the hierarchical organisation of collagen VI microfibrils at nanometre to micrometre length scales.
        Acta Biomater. 2017; 52: 21-32
        • Specks U.
        • Nerlich A.
        • Colby T.V.
        • Wiest I.
        • Timpl R.
        Increased expression of type VI collagen in lung fibrosis.
        Am. J. Respir. Crit. Care Med. 1995; 151: 1956-1964
        • Calvier L.
        • Miana M.
        • Reboul P.
        • Cachofeiro V.
        • Martinez-Martinez E.
        • de Boer R.A.
        • et al.
        Galectin-3 mediates aldosterone-induced vascular fibrosis.
        Arterioscler. Thromb. Vasc. Biol. 2013; 33: 67-75
        • Wang X.
        • Wang Y.
        • Zhang J.
        • Guan X.
        • Chen M.
        • Li Y.
        • et al.
        Galectin-3 contributes to vascular fibrosis in monocrotaline-induced pulmonary arterial hypertension rat model.
        J. Biochem. Mol. Toxicol. 2017; 31https://doi.org/10.1002/jbt.21879
        • Fenster B.E.
        • Lasalvia L.
        • Schroeder J.D.
        • Smyser J.
        • Silveira L.J.
        • Buckner J.K.
        • et al.
        Galectin-3 levels are associated with right ventricular functional and morphologic changes in pulmonary arterial hypertension.
        Heart Vessels. 2016; 31: 939-946
        • Calvier L.
        • Legchenko E.
        • Grimm L.
        • Sallmon H.
        • Hatch A.
        • Plouffe B.D.
        • et al.
        Galectin-3 and aldosterone as potential tandem biomarkers in pulmonary arterial hypertension.
        Heart. 2016; 102: 390-396
        • Mazurek J.A.
        • Horne B.D.
        • Saeed W.
        • Sardar M.R.
        • Zolty R.
        Galectin-3 levels are elevated and predictive of mortality in pulmonary hypertension.
        Heart Lung Circ. 2017; 26: 1208-1215
        • Feng W.
        • Wu X.
        • Li S.
        • Zhai C.
        • Wang J.
        • Shi W.
        • et al.
        Association of serum galectin-3 with the acute exacerbation of chronic obstructive pulmonary disease.
        Med. Sci. Monit. 2017; 23: 4612-4618
        • Watanabe E.
        • Kato K.
        • Gono T.
        • Chiba E.
        • Terai C.
        • Kotake S.
        Serum levels of galectin-3 in idiopathic inflammatory myopathies: a potential biomarker of disease activity.
        Rheumatology (Oxford). 2021; 60: 322-332
        • d'Alessandro M.
        • De Vita E.
        • Bergantini L.
        • Mazzei M.A.
        • di Valvasone S.
        • Bonizzoli M.
        • et al.
        Galactin-1, 3 and 9: potential biomarkers in idiopathic pulmonary fibrosis and other interstitial lung diseases.
        Respir. Physiol. Neurobiol. 2020; 282: 103546
        • Inohara H.
        • Raz A.
        Effects of natural complex carbohydrate (citrus pectin) on murine melanoma cell properties related to galectin-3 functions.
        Glycoconj. J. 1994; 11: 527-532
        • Nangia-Makker P.
        • Hogan V.
        • Honjo Y.
        • Baccarini S.
        • Tait L.
        • Bresalier R.
        • et al.
        Inhibition of human cancer cell growth and metastasis in nude mice by oral intake of modified citrus pectin.
        J. Natl. Cancer Inst. 2002; 94: 1854-1862
        • Platt D.
        • Raz A.
        Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.
        J. Natl. Cancer Inst. 1992; 84: 438-442
        • Hao M.
        • Li M.
        • Li W.
        Galectin-3 inhibition ameliorates hypoxia-induced pulmonary artery hypertension.
        Mol. Med. Rep. 2017; 15: 160-168
        • Luo H.
        • Liu B.
        • Zhao L.
        • He J.
        • Li T.
        • Zha L.
        • et al.
        Galectin-3 mediates pulmonary vascular remodeling in hypoxia-induced pulmonary arterial hypertension.
        J. Am. Soc. Hypertens. 2017; 11: 673-683.e673
        • Barman S.A.
        • Chen F.
        • Li X.
        • Haigh S.
        • Stepp D.W.
        • Kondrikov D.
        • et al.
        Galectin-3 promotes vascular remodeling and contributes to pulmonary hypertension.
        Am. J. Respir. Crit. Care Med. 2018; 197: 1488-1492
        • Hirani N.
        • MacKinnon A.C.
        • Nicol L.
        • Ford P.
        • Schambye H.
        • Pedersen A.
        • et al.
        Target inhibition of galectin-3 by inhaled TD139 in patients with idiopathic pulmonary fibrosis.
        Eur. Respir. J. 2021; 57: 2002559
        • Traber P.G.
        • Zomer E.
        Therapy of experimental NASH and fibrosis with galectin inhibitors.
        PLoS One. 2013; 8: e83481
        • Harrison S.A.
        • Marri S.R.
        • Chalasani N.
        • Kohli R.
        • Aronstein W.
        • Thompson G.A.
        • et al.
        Randomised clinical study: GR-MD-02, a galectin-3 inhibitor, vs. placebo in patients having non-alcoholic steatohepatitis with advanced fibrosis.
        Aliment. Pharmacol. Ther. 2016; 44: 1183-1198
        • Chalasani N.
        • Abdelmalek M.F.
        • Garcia-Tsao G.
        • Vuppalanchi R.
        • Alkhouri N.
        • Rinella M.
        • et al.
        Effects of belapectin, an inhibitor of galectin-3, in patients with nonalcoholic steatohepatitis with cirrhosis and portal hypertension.
        Gastroenterology. 2020; 158: 1334-1345.e1335
        • Nguyen M.N.
        • Ziemann M.
        • Kiriazis H.
        • Su Y.
        • Thomas Z.
        • Lu Q.
        • et al.
        Galectin-3 deficiency ameliorates fibrosis and remodeling in dilated cardiomyopathy mice with enhanced Mst1 signaling.
        Am. J. Physiol. Heart Circ. Physiol. 2019; 316: H45-H60
        • Xu G.R.
        • Zhang C.
        • Yang H.X.
        • Sun J.H.
        • Zhang Y.
        • Yao T.T.
        • et al.
        Modified citrus pectin ameliorates myocardial fibrosis and inflammation via suppressing galectin-3 and TLR4/MyD88/NF-kappaB signaling pathway.
        Biomed. Pharmacother. 2020; 126: 110071
        • Harrison S.A.
        • Dennis A.
        • Fiore M.M.
        • Kelly M.D.
        • Kelly C.J.
        • Paredes A.H.
        • et al.
        Utility and variability of three non-invasive liver fibrosis imaging modalities to evaluate efficacy of GR-MD-02 in subjects with NASH and bridging fibrosis during a phase-2 randomized clinical trial.
        PLoS One. 2018; 13: e0203054
        • Ricard-Blum S.
        • Baffet G.
        • Theret N.
        Molecular and tissue alterations of collagens in fibrosis.
        Matrix Biol. 2018; 68-69: 122-149
        • Flores-Ibarra A.
        • Vertesy S.
        • Medrano F.J.
        • Gabius H.J.
        • Romero A.
        Crystallization of a human galectin-3 variant with two ordered segments in the shortened N-terminal tail.
        Sci. Rep. 2018; 8: 9835
        • Miller M.C.
        • Zheng Y.
        • Yan J.
        • Zhou Y.
        • Tai G.
        • Mayo K.H.
        Novel polysaccharide binding to the N-terminal tail of galectin-3 is likely modulated by proline isomerization.
        Glycobiology. 2017; 27: 1038-1051
        • Pineda M.
        • Corvo L.
        • Callejas-Hernandez F.
        • Fresno M.
        • Bonay P.
        Trypanosoma cruzi cleaves galectin-3 N-terminal domain to suppress its innate microbicidal activity.
        Clin. Exp. Immunol. 2020; 199: 216-229
        • Pelletier I.
        • Sato S.
        Specific recognition and cleavage of galectin-3 by Leishmania major through species-specific polygalactose epitope.
        J. Biol. Chem. 2002; 277: 17663-17670
        • Zhao Z.
        • Xu X.
        • Cheng H.
        • Miller M.C.
        • He Z.
        • Gu H.
        • et al.
        Galectin-3 N-terminal tail prolines modulate cell activity and glycan-mediated oligomerization/phase separation.
        Proc. Natl. Acad. Sci. U. S. A. 2021; 118e2021074118
        • Mauris J.
        • Woodward A.M.
        • Cao Z.
        • Panjwani N.
        • Argueso P.
        Molecular basis for MMP9 induction and disruption of epithelial cell-cell contacts by galectin-3.
        J. Cell Sci. 2014; 127: 3141-3148
        • Wang S.F.
        • Tsao C.H.
        • Lin Y.T.
        • Hsu D.K.
        • Chiang M.L.
        • Lo C.H.
        • et al.
        Galectin-3 promotes HIV-1 budding via association with Alix and Gag p6.
        Glycobiology. 2014; 24: 1022-1035
        • Bocker S.
        • Elling L.
        Binding characteristics of galectin-3 fusion proteins.
        Glycobiology. 2017; 27: 457-468
        • Fermino M.L.
        • Polli C.D.
        • Toledo K.A.
        • Liu F.T.
        • Hsu D.K.
        • Roque-Barreira M.C.
        • et al.
        LPS-induced galectin-3 oligomerization results in enhancement of neutrophil activation.
        PLoS One. 2011; 6: e26004
        • Lo T.H.
        • Chen H.L.
        • Yao C.I.
        • Weng I.C.
        • Li C.S.
        • Huang C.C.
        • et al.
        Galectin-3 promotes noncanonical inflammasome activation through intracellular binding to lipopolysaccharide glycans.
        Proc. Natl. Acad. Sci. U. S. A. 2021; 118e2026246118
        • Kahsai A.W.
        • Cui J.
        • Kaniskan H.U.
        • Garner P.P.
        • Fenteany G.
        Analogs of tetrahydroisoquinoline natural products that inhibit cell migration and target galectin-3 outside of its carbohydrate-binding site.
        J. Biol. Chem. 2008; 283: 24534-24545
        • Sethi A.
        • Sanam S.
        • Alvala M.
        Non-carbohydrate strategies to inhibit lectin proteins with special emphasis on galectins.
        Eur. J. Med. Chem. 2021; 222: 113561
        • Yang R.Y.
        • Hsu D.K.
        • Liu F.T.
        Expression of galectin-3 modulates T-cell growth and apoptosis.
        Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 6737-6742
        • Fukumori T.
        • Takenaka Y.
        • Oka N.
        • Yoshii T.
        • Hogan V.
        • Inohara H.
        • et al.
        Endogenous galectin-3 determines the routing of CD95 apoptotic signaling pathways.
        Cancer Res. 2004; 64: 3376-3379
        • Liu L.
        • Sakai T.
        • Sano N.
        • Fukui K.
        Nucling mediates apoptosis by inhibiting expression of galectin-3 through interference with nuclear factor kappaB signalling.
        Biochem. J. 2004; 380: 31-41
        • Liu F.T.
        • Patterson R.J.
        • Wang J.L.
        Intracellular functions of galectins.
        Biochim. Biophys. Acta. 2002; 1572: 263-273
        • Elad-Sfadia G.
        • Haklai R.
        • Balan E.
        • Kloog Y.
        Galectin-3 augments K-Ras activation and triggers a Ras signal that attenuates ERK but not phosphoinositide 3-kinase activity.
        J. Biol. Chem. 2004; 279: 34922-34930
        • Lee Y.J.
        • Song Y.K.
        • Song J.J.
        • Siervo-Sassi R.R.
        • Kim H.R.
        • Li L.
        • et al.
        Reconstitution of galectin-3 alters glutathione content and potentiates TRAIL-induced cytotoxicity by dephosphorylation of Akt.
        Exp. Cell Res. 2003; 288: 21-34
        • Oka N.
        • Nakahara S.
        • Takenaka Y.
        • Fukumori T.
        • Hogan V.
        • Kanayama H.O.
        • et al.
        Galectin-3 inhibits tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by activating Akt in human bladder carcinoma cells.
        Cancer Res. 2005; 65: 7546-7553
        • Shimura T.
        • Takenaka Y.
        • Tsutsumi S.
        • Hogan V.
        • Kikuchi A.
        • Raz A.
        Galectin-3, a novel binding partner of beta-catenin.
        Cancer Res. 2004; 64: 6363-6367
        • Massa S.M.
        • Cooper D.N.
        • Leffler H.
        • Barondes S.H.
        L-29, an endogenous lectin, binds to glycoconjugate ligands with positive cooperativity.
        Biochemistry. 1993; 32: 260-267
        • Sato S.
        • Hughes R.C.
        Binding specificity of a baby hamster kidney lectin for H type I and II chains, polylactosamine glycans, and appropriately glycosylated forms of laminin and fibronectin.
        J. Biol. Chem. 1992; 267: 6983-6990
        • Hikita C.
        • Vijayakumar S.
        • Takito J.
        • Erdjument-Bromage H.
        • Tempst P.
        • Al-Awqati Q.
        Induction of terminal differentiation in epithelial cells requires polymerization of hensin by galectin 3.
        J. Cell Biol. 2000; 151: 1235-1246
        • Ochieng J.
        • Warfield P.
        • Green-Jarvis B.
        • Fentie I.
        Galectin-3 regulates the adhesive interaction between breast carcinoma cells and elastin.
        J. Cell Biochem. 1999; 75: 505-514
        • Ochieng J.
        • Leite-Browning M.L.
        • Warfield P.
        Regulation of cellular adhesion to extracellular matrix proteins by galectin-3.
        Biochem. Biophys. Res. Commun. 1998; 246: 788-791
        • Probstmeier R.
        • Montag D.
        • Schachner M.
        Galectin-3, a beta-galactoside-binding animal lectin, binds to neural recognition molecules.
        J. Neurochem. 1995; 64: 2465-2472
        • Cherayil B.J.
        • Weiner S.J.
        • Pillai S.
        The Mac-2 antigen is a galactose-specific lectin that binds IgE.
        J. Exp. Med. 1989; 170: 1959-1972
        • Lakshminarayan R.
        • Wunder C.
        • Becken U.
        • Howes M.T.
        • Benzing C.
        • Arumugam S.
        • et al.
        Galectin-3 drives glycosphingolipid-dependent biogenesis of clathrin-independent carriers.
        Nat. Cell Biol. 2014; 16: 595-606
        • Dalton P.
        • Christian H.C.
        • Redman C.W.
        • Sargent I.L.
        • Boyd C.A.
        Membrane trafficking of CD98 and its ligand galectin 3 in BeWo cells–implication for placental cell fusion.
        FEBS J. 2007; 274: 2715-2727
        • Feuk-Lagerstedt E.
        • Movitz C.
        • Pellme S.
        • Dahlgren C.
        • Karlsson A.
        Lipid raft proteome of the human neutrophil azurophil granule.
        Proteomics. 2007; 7: 194-205
        • Partridge E.A.
        • Le Roy C.
        • Di Guglielmo G.M.
        • Pawling J.
        • Cheung P.
        • Granovsky M.
        • et al.
        Regulation of cytokine receptors by Golgi N-glycan processing and endocytosis.
        Science. 2004; 306: 120-124
        • Liu W.
        • Hsu D.K.
        • Chen H.Y.
        • Yang R.Y.
        • Carraway 3rd, K.L.
        • Isseroff R.R.
        • et al.
        Galectin-3 regulates intracellular trafficking of EGFR through Alix and promotes keratinocyte migration.
        J. Invest. Dermatol. 2012; 132: 2828-2837
        • Chen H.Y.
        • Fermin A.
        • Vardhana S.
        • Weng I.C.
        • Lo K.F.
        • Chang E.Y.
        • et al.
        Galectin-3 negatively regulates TCR-mediated CD4+ T-cell activation at the immunological synapse.
        Proc. Natl. Acad. Sci. U. S. A. 2009; 106: 14496-14501