Journal Article

Expression of CX3CL1/fractalkine by mesangial cells <i>in vitro</i> and in acute anti-Thy1 glomerulonephritis in rats

Yung-Ming Chen, Mi-I Hu-Tsai, Shuei-Liong Lin, Tun-Jun Tsai and Bor-Shen Hsieh

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 18, issue 12, pages 2505-2514
Published in print December 2003 | ISSN: 0931-0509
Published online December 2003 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfg457
Expression of CX3CL1/fractalkine by mesangial cells in vitro and in acute anti-Thy1 glomerulonephritis in rats

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Background. Mesangial cells (MCs) can promote glomerular macrophage accumulation in glomerulonephritis through production of a variety of chemokines. This study investigated the potential of MCs to synthesize CX3CL1/fractalkine, a CX3C chemokine, both in vitro and in acute anti-Thy1 glomerulonephritis in rats.

Methods. Anti-Thy1 glomerulonephritis was induced in Wistar rats by a single injection of mouse anti-rat Thy1.1 antibody intravenously. Glomerular mRNAs for CX3CL1/fractalkine, CCL2/monocyte chemoattractant protein (MCP)-1, and their cognate receptors, CX3CR1 and CCR2, were determined by northern blot analysis or reverse-transcription polymerase chain reaction. CX3CL1/fractalkine mRNA and protein expression in vivo was localized by in situ hybridization and immunohistochemistry. Monocytes/macrophages and activated MCs were detected by immunohistochemistry. Regulation of CX3CL1/fractalkine expression in cultured MCs was determined by northern and western blot analysis.

Results. After induction of anti-Thy1 disease, glomerular CX3CL1/fractalkine mRNA was significantly up-regulated, peaking at 2 h and sustaining into day 5 of the nephritis. A corresponding increase in urinary CX3CL1/fractalkine protein was evident after day 1 of the nephritis, but became more prominent during the MC proliferative phase (days 3–5). Meanwhile, induction of glomerular CCL2/MCP-1 mRNA and urinary CCL2/MCP-1 protein occurred within 24 h, and was barely detectable after day 3 of the nephritis. Urinary CCL2/MCP-1, but not CX3CL1/fractalkine, correlated with glomerular macrophage accumulation (r = 0.936, P<0.01) and glomerular CCR2 mRNA expression (r = 0.965, P<0.01). In contrast, only urinary CX3CL1/fractalkine coincided temporally to glomerular mRNA for CX3CR1 (r = 0.809, P < 0.01). Combined in situ hybridization and immunohistochemistry revealed that activated MCs were a major source for CX3CL1/fractalkine mRNA and protein during days 3–5 of the nephritis. Incubation of cultured MCs with tumour necrosis factor (TNF)-α, interleukin (IL)-1β, platelet-derived growth factor (PDGF)-AB or basic fibroblast growth factor (bFGF) significantly up-regulated CX3CL1/fractalkine mRNA and protein expression. This cytokine- and growth factor-stimulated CX3CL1/fractalkine expression could be abolished by the nuclear factor-κB inhibitors, curcumin and MG132.

Conclusions. Our data demonstrate that activated MCs are a source for the augmented glomerular CX3CL1/fractalkine expression during the proliferative phase of acute anti-Thy1 glomerulonephritis. Up-regulation of MC CX3CL1/fractalkine by TNF-α, IL-1β, PDGF-AB and bFGF is mediated, at least in part, via the nuclear factor-κB signalling pathway. The differential expression of CCL2/MCP-1 and CX3CL1/fractalkine may sequentially recruit distinct subsets of monocytes to the glomerulus during acute anti-Thy1 glomerulonephritis.

Keywords: anti-Thy1 glomerulonephritis; CCL2/MCP-1, CCR2; CX3CL1/fractalkine; CX3CR1; mesangial cells

Journal Article.  4915 words.  Illustrated.

Subjects: Nephrology

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