Netting neutrophils in autoimmune small-vessel vasculitis

Neutrophils release neutrophil extracellular traps (NETs), chromatin fibers that can ensnare bacteria. In small-vessel vasculitis (SVV), a chronic inflammatory condition linked to antineutrophil autoantibodies, these NETs express SVV-associated autoantigens, accumulate in inflamed kidneys and promote the autoimmune response against neutrophils in people with SVV. Small-vessel vasculitis (SVV) is a chronic autoinflammatory condition linked to antineutrophil cytoplasm autoantibodies (ANCAs). Here we show that chromatin fibers, so-called neutrophil extracellular traps (NETs), are released by ANCA-stimulated neutrophils and contain the targeted autoantigens proteinase-3 (PR3) and myeloperoxidase (MPO). Deposition of NETs in inflamed kidneys and circulating MPO-DNA complexes suggest that NET formation triggers vasculitis and promotes the autoimmune response against neutrophil components in individuals with SVV.