Oxidized LDL immune complexes stimulate collagen IV production in mesangial cells via Fc gamma receptors I and III

Diabetic nephropathy is characterized by progressive mesangial expansion. Although we have reported that circulating oxidized LDL-containing immune complexes (oxLDL-IC) are associated with abnormal levels of albuminuria, the underlying mechanisms have not been investigated. In this study, we have studied the effect of oxLDL-IC on collagen IV expression by mesangial cells. We found that oxLDL-IC markedly stimulated collagen IV expression in a concentration- and time-dependent fashion while oxLDL only had moderate effect. We also found that oxLDL-IC stimulated collagen IV expression by engaging Fc gamma receptor (Fc gamma R) I and III, but not Fc gamma RII, and that p38 MAPK, JNK and PKC pathways were involved in collagen IV expression. Furthermore, we found that oxLDL-IC stimulated Fc gamma RI expression, suggesting a positive feedback mechanism involved in oxLDL-IC-stimulated collagen IV expression. Taken together, this study showed that oxLDL-IC stimulated collagen IV in mesangial cells via Fc gamma RI and Fc gamma RIII, and the expression of Fc gamma RI was increased by oxLDL-IC. Published by Elsevier Inc.