IL17A and arthritic joint disease: In addition, in an animal study using SKG mice harboring a microbiota dominated by Prevotella copri from RA patients, interleukin-17 (IL-17) was increased with a higher number of intestinal Th17 cells, which response to the arthritis-related autoantigen 60S ribosomal protein L23a (RPL23A) in the lymphocytes of regional lymph nodes and the colon, leading to the development of arthritis.