IL17A and inflammatory bowel disease: The reduced number of peripheral blood Tregs and the increased numbers of peripheral Th17 cells were observed in IBD patients,11, 24 whereas FoxP3 mRNA expression levels in the mucosa are elevated, and elevated IL‐17A, IL‐1β, and IL‐6 mRNA levels are also elevated in IBD.11 Tregs suppress colonic inflammation by downregulating Th17 through TGF‐β.15, 25