IL17A and inflammatory bowel disease: Th17 and Th22 cells, along with serum IL-17 and MCP-1 (Table 2), play a protective role in IBD promoting barrier function through epithelial cell regeneration, host protection through immune cell recruitment and maintaining intestinal homeostasis.28,29 Within the T helper (Th) cell populations, Th22 cells and IL-17+ IL-22+ cells were significantly increased in the MD versus the OO and CO fed diets (Figure 4d).