A systematic review of 10 studies involving biologic therapies reported that the gut microbiota of IBD patients who responded to anti-TNF agents (8 studies) had higher α-diversity and greater relative abundances of genera from the Clostridiales order, including Faecalibacterium, Roseburia or Clostridium (butyrate-producers) either at baseline or during follow-up[143]. Here, TNF is linked to irritable bowel syndrome.