IL17A and Crohn disease: Previous research has shown that the levels of Th1 cytokines, such as interferon-γ (IFNγ) and interleukin (IL)-12, along with Th17 cytokines, including IL-17A and IL-23, are markedly elevated in Crohn’s disease and in mouse colitis models including TNBS-induced colitis, which is a relevant model for studying Crohn’s disease [29,30,31,32].