PRTN3 and rheumatoid arthritis: Although other factors may be able to induce protein citrullination [7], Porphyromonas gingivalis a key pathogen associated with the pathogenesis of periodontitis by inducing dysbiotic changes in the subgingival biofilm [8, 9] releases a specific deaminase, which has been linked to protein citrullination, thereby with potential to stimulate ACPA formation in RA patients [10, 11].