Angiogenic Effects of Interleukin 8 (CXCL8) in Human Intestinal Microvascular Endothelial Cells Are Mediated by CXCR2

doi:10.1074/jbc.M208231200

Angiogenic Effects of Interleukin 8 (CXCL8) in Human Intestinal Microvascular Endothelial Cells Are Mediated by CXCR2*

From the Departments of ^‡Medicine,^§Microbiology and Molecular Genetics, and ^¶Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and the ^‖Department of Medicine B, University of Münster, Münster 48149, Germany

Abstract

Angiogenesis plays a critical role in metastasis and tumor growth. Human tumors, including colorectal adenocarcinoma, secrete angiogenic factors, inducing proliferation and chemotaxis of microvascular endothelial cells, eventually leading to tumor neovascularization. The chemokine interleukin 8 (IL-8; CXCL8) exerts potent angiogenic properties on endothelial cells through interaction with its cognate receptors CXCR1 and CXCR2. As CXCR1 and CXCR2 expression is differentially regulated in tissue-specific endothelial cells and effects of IL-8 on intestinal endothelial cells are not defined, we characterized the potential IL-8-induced angiogenic mechanisms in primary cultures of human intestinal microvascular endothelial cells (HIMEC) and IL-8 receptor expression in human intestinal microvessels. CXCR1 and CXCR2 expression on HIMEC were defined using reverse transcriptase-PCR, immunohistochemistry, flow cytometry, and Western blot analysis. IL-8-induced downstream signaling events were assessed using immunoblot analysis and immunofluorescence. The angiogenic effects of IL-8 on HIMEC were determined using proliferation and chemotaxis assays. HIMEC responded to IL-8 with rapid stress fiber assembly, chemotaxis, enhanced proliferation, and phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK 1/2). HIMEC express CXCR2, but not CXCR1. Neutralizing antibodies to CXCR2 diminished IL-8-induced chemotaxis and stress fiber assembly. Specific inhibitors of ERK 1/2 and phosphoinositide 3-kinase abrogated endothelial tube formation and IL-8-induced chemotaxis in HIMEC. IL-8 elicits angiogenic responses in microvascular endothelial cells isolated from human intestine by engaging CXCR2. We confirmed tissue expression of CXCR2 in human intestinal microvessels. Supported by the notion that malignant colonic epithelial cells overexpress IL-8, CXCR2 blockade may be a novel target for anti-angiogenic therapy in colorectal adenocarcinoma.

Footnotes

↵* This work was supported by National Institutes of Health Grants DK056234, DK057139 (to D. G. B.), and DK02808 (to M. B. D.) and grants from the Deutsche Gesellschaft für Verdauungs- und Stoffwechselkrankheiten (to J. H.), the Crohn's and Colitis Foundation of America (to D. G. B.), the Cancer Center (to D. G. B., P. R., and M. B. D.), and the Digestive Disease Center (to D. G. B., P. R., and M. F. O.) of the Medical College of Wisconsin.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵** To whom correspondence should be addressed: Division of Gastroenterology and Hepatology, Dept. of Medicine, Medical College of Wisconsin, 9200 W. Wisconsin Ave., Milwaukee, WI 53226. Tel.: 414-456-6845; Fax: 414-456-6214; E-mail: dbinion@mcw.edu.
Published, JBC Papers in Press, December 20, 2002, DOI 10.1074/jbc.M208231200
Abbreviations:

EC

endothelial cell

ERK

extracellular signal-regulated kinase

HIMEC

human intestinal microvascular endothelial cells

IL-8

interleukin 8

MAPK

mitogen-activated protein kinase

PI3K

phosphoinositide 3-kinase

VEGF

vascular endothelial growth factor

TNF-α

tumor necrosis factor α

IFN

interferon

LPS

lipopolysaccharide

FBS

fetal bovine serum

BSA

bovine serum albumin

PBMC

peripheral blood mononuclear cells

PBS

phosphate-buffered saline

DARC

Duffy antigen receptor for chemokines
- Received August 12, 2002.
- Revision received December 17, 2002.
The American Society for Biochemistry and Molecular Biology, Inc.