MPO and nephritis: In addition, C5a has broad pro-inflammatory activity through its receptor C5aR, and contributes to the pathogenesis of some types of nephritis such as anti-glomerular basement (GBM) glomerulonephritis, lupus nephritis, anti-myeloperoxidase (MPO)-induced necrotizing crescentic glomerulonephritis (NCGN) [20–23].