PRTN3 and rheumatoid arthritis: Of note, the presence of anti-citrullinated protein autoantibodies (ACPA), a hallmark feature of RA, in the vaginal fluid of RA females in premenopausal age supports the hypothesis that some urogenital mucosal pathobiont may play a role in stimulating a specific humoral response, NETs generation, and predisposition to RA development.