C3a receptor activation promotes uric acid or LPS-induced CCL2 production in proximal tubular epithelial cells

Abstract

Background To identify the role of the interaction of complement fragment 3a (C3a) and its receptor C3aR in uric acid (UA) or lipopolysaccharide (LPS)-induced CCL2 expression in human renal proximal tubular epithelial cell line HK-2.Methods HK-2 cells were cultured in vitro and treated with UA or LPS to induce the production of CCL2. To determine the role of C3a-C3aR interaction in CCL2 production, HK-2 cells exposed to UA or LPS were pretreated with the small molecule sb290157 (1μmol/l) or recombinant C3a protein (100nmol/l) to block or amplify C3a-C3aR interaction. The expression of CCL2, C3 and C3aR were detected by real-time quantitative PCR (Q-PCR), enzyme-linked immunosorbent assay (ELISA) and Western Blotting. Results 12 hours of UA (150μmol/L) stimulation or 8 hours of LPS (5μg/ml) treatment significantly induced CCL2 and C3 mRNA transcription in HK-2 cells. The expression of CCL2 induced by UA or LPS could be abrogated by C3aR blockade. C3a stimulation alone has little effect on inducing CCL2 expression in HK-2 cells. However, when it stimulated the HK-2 cells together with UA or LPS, it could remarkably potentiate UA or LPS-induced CCL2 expression.Conclusion The activation of C3aR provides an important co-stimulating signal for CCL2 production in HK-2 cells and blocking the interaction of C3a-C3aR will significantly inhibit UA or LPS induced CCL2 production.