C3AR1 and systemic lupus erythematosus: C3aR signaling in kidney diseases was found to be involved in the pathogenesis of membranous nephropathy [11], focal and segmental glomerulosclerosis [12], lupus [13], IgA nephropathy [14], p-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) vasculitis [15], C3 glomerulopathy [16], and membrano-proliferative glomerulonephritis [17].