IL9 and irritable bowel syndrome: Biologic agents classified as IBD therapeutics include monoclonal antibodies against tumor necrosis factor-alpha (TNF-α), such as certolizumab, adalimumab, golimumab, and infliximab; agents targeting integrins, such as natalizumab (which targets the α4 subunit in α4β7 and α4β1 integrins, approved for CD); and ustekinumab (a monoclonal antibody directed to the p40 subunit of IL-12 and IL-23).