IL17A and Arthritis: The available literature indicates C. aerofaciens as a pathobiont, which is also overabundant in metabolic syndrome,41 type 2 diabetes,42 autoimmune polyendocrine syndrome type 1,43 and psoriatic arthritis (together with the species Dorea formicigenerans).44 Furthermore, C. aerofaciens exacerbates arthritis in a collagen-induced arthritis model by increasing gut permeability and triggering the expression of IL-17, CXCL1, and CXCL5 in intestinal epithelial cells.45