Chen J. et al. (2016) also showed the abundance of Collinsella is associated with pathologic expression of IL-17A and deterioration of rheumatoid arthritis. Furthermore, the high levels of Campylobacter jejuni leads to alteration in gut microbiota population and expression of IL-17A, IL-22, and TNF-α in pathologic format (Heimesaat et al., 2016; Rodrigues et al., 2018). A feature of IBD-ulcerative colitis and Crohn’s disease was a change in ’healthy’ microbiota such as Bifidobacterium and Bacteriodes, and a concurrent reduction in SCFAs (Hudafaujan et al., 2010; Chaysavanh et al., 2012). Here, IL17A is linked to ulcerative colitis.