IL17A and rheumatoid arthritis: In summary, M. tenuis consistently showed strong pro‐inflammatory effect and elevated IL‐17A levels, but E. rectale showed discrepancy in statistic and experimentally validated correlations: The statistics suggested that E. rectale was negatively correlated to RA and was putatively anti‐inflammatory, while the experimental results demonstrated that E. rectale promoted inflammation and significantly reduced IL‐10, IL‐17, IL‐2 and IL‐12p70.