PADI4 and arthritic joint disease: Multiple studies have shown a protective effect in autoimmune diseases when PAD4−/− animals have been used, so it would be likely that a PAD inhibitor would have some effect in ameliorating autoimmunity in diseases in which NETs are likely to play a role such as lupus, atherosclerosis, arthritis, diabetes, and AAV (86, 87, 92–95).