Given that IL-10 is a major product of Treg cells and plays a crucial role in Treg cell-mediated colitis alleviation 28, and that the pathogenic roles of IL-17A, IL-22, and IL-2 produced by Th17 cells have been well documented in IBD 29, we examined the alteration in cytokine production and Treg/Th17 balance in the intestinal mucosa. Here, IL17A is linked to inflammatory bowel disease.