The leukocyte and myeloid cell-specific knockdown of HIF-1α has been found to result in more severe colonic inflammation with increased levels of pro-inflammatory cytokines in dextran sulfate sodium (DSS)-induced IBD model mice [18,20,21,22], indicating that hypoxia underlies the polarization of inflammatory T cells such as type 1 T helper (Th1) and Th17 cells in inflamed tissues. Here, HIF1A is linked to inflammatory bowel disease.