IL17A and rheumatoid arthritis: Collinsella, Eggerthella, and Faecalibacterium segregate with RA in random forest modeling (121) Collinsella and Eggerthella correlate with increased intestinal permeability, mucosal inflammation, and immune response, and Collinsella is confirmed to correlate with increased proinflammatory cytokine IL-17A, gut permeability, and RA disease severity (119, 121).