Upregulation of Monocyte Chemoattractant Protein-1 in Early Stage Diffuse Scleroderma

Abstract

Fibroblast derived monocyte chemoattractant protein1 (MCP1 or CCU) is a candidate mediator that may link inflammatory and fibrotic processes in scleroderma (SSc) pathogenesis. This study examines the relationship between MCP-1 ligand and receptor expression and stage and subset of scleroderma. METHODS: Serum samples and skin biopsies were examined from 54 patients with SSc and 12 healthy controls. 20 had early (within 3 years from onset) diffuse cutaneous SSc (dcSSc), 14 late dcSSc and 20 limited cutaneous SSc (1cSSc). Levels of MCP-1 in serum were measured by commercial ELISA. Expression of MCP-1 and its major receptor CCRZ in snap-frozen skin biopsies was determined by immunohistochemistry. Fibroblasts were cultured from a randomly selected subgroup of early dcSSc and culture supernatants examined by western blot. Chemokine receptor expression (CCR2, CXCRZ and CCRS) on fibroblasts was determined by flow cytometry, comparing receptor-specific antibody binding with an isotype matched control. RESULTS: MCP1 serum levels (meansem) were significantly elevated in SSc patients (342&4 pg/ml) compared to controls (132i26pg/ml, p=0.002) and were highest in the early dcSSc subset (433i47 pg/ml) compared to late dcSSc (307+_41 pg/ml) and lcSSc (276228 pg/ml). Western Blot analysis of cultured fibroblasts supernatants confirmed substantial overproduction (meanksem) of MCP-I by cells from early dcSSc (n=8) (RDU=37.5+11.2) compared with normal fibroblasts (RDU=8.3d2.0) ( ~ 3 . 0 0 2 ) . lmmunohistochemistry showed strong expression of MCP1 and CCRZ in skin from all patients with early stage dcSSc. but expression in late stage dcSSc and lcSSc was weaker or absent. By flow cytometry CCRZ was detectable only on early-stage dcSSc, both normal and SSc fibroblasts expressed CXCR2 whereas CCR5 was not detected. CONCLUSION: High serum levels of MCP-I in early diffuse disease, overproduction by fibroblasts cultured from early-stage dcSSc biopsies and CCR2 expression on fibroblasts confirm upregulation of the MCP-I ligand-receptor axis in SSc and suggest that chemokine antagonism may be a logical therapeutic strategy.