IL17A and rheumatoid arthritis: P. histicola has demonstrated reparative effects in AR when administered in combination with a tumor necrosis factor (TNF) inhibitor in DQ8 mouse models [109,112], additionally, other studies employing similar methodologies have reported a decreased incidence of RA as a result of reduced serum levels of cytokines such as IL-2, IL-17, and TNF-α.