PADI4 and Autoimmunity: As a special way of capturing invasive bacteria, NETs contain abundant cytosolic proteins, especially those with post-translational modifications, such as PAD4 that drives citrullination, which is an important potential source of self-antigens to promote the loss of immune tolerance and autoimmunity (17) and increase the generation of antineutrophil cytoplasmic antibodies (ANCAs) (18) and anti-cyclic citrullinated peptide antibodies (ACPAs) (19).