How the Availability of Anti-C5a Agents Could Change the Management of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a cluster of potentially life-threatening disorders, often involving the kidney with a necrotizing crescentic glomerulonephritis with scanty deposition of immunoglobulins and complement. Historically the role of complement has been considered ancillary. Recently, an anti-myeloperoxidase (MPO) AAV model in complement-deficient mice has shown an involvement for the complement cascade in the development of the renal injuries. Further animal studies showing that in contrast to mice deficient for factor B and C5 animals deficient for C4 were susceptible to AAV development by injection of anti-MPO antibodies emphasized the specific involvement of the alternative pathway. Consonantly, the C5a receptor (Cd88) blockade was found to protect mice from MPO-AAV. CCX168, i.e., avacopan, a powerful inhibitor of C5a receptor that can be administered orally, was shown to reduce the proinflammatory effects of C5a and abolish the activation of neutrophils, their migration and adherence to endothelium, and the vascular endothelial cell retraction that increases permeability.