IL17A and Crohn disease: Inflamed mucosal tissues and inflammatory diseases of the gut [inflammatory bowel diseases (IBDs) and Crohn’s disease (CD)] were associated with increased frequency of IFN-γ/IL-17A-producing ILCs (Geremia et al., 2011; Bernink et al., 2013) and reduced frequency of IL-22-producing ILCs (Takayama et al., 2010; Bernink et al., 2015).