mTOR promotes an inflammatory response through the HIF1 signaling pathway in ulcerative colitis

The imbalance between T helper cell 17 （Th17）and regulatory T cells (Treg) cells leading to inflammation has an important role in the pathogenesis of ulcerative colitis (UC). Mammalian target of rapamycin (mTOR) can regulate the differentiation of T cells, but the specific pathway leading mTOR to regulate Th17/Treg cells in UC remains unclear. Our aim with this study was to investigate the effects of mTOR overexpression and silencing on the hypoxia inducible factor-1α (HIF-1α) - Th17/Treg signaling pathway. To mimic a human study, we established a colon cancer epithelial cell line (HT-29) co-culture system with human CD4⁺ T cells, and we treated the cells with TNF-α. We observed the effects of mTOR on the HIF-Th17/Treg signaling pathway to determine whether mTOR is involved in the regulatory mechanism. Under the stimulation of TNF-α, the levels of HIF-1α in CD4⁺T cells were increased in the HT-29 co-culture with CD4⁺ T cells, promoting glycolysis, increasing the Th17 proportion, decreasing the Treg proportion, increasing the pro-inflammatory factors levels, and decreasing the anti-inflammatory factors levels. Moreover, after mTOR silencing, the HIF-1α level and cell glycolysis levels decreased, Th17 cell differentiation decreased, the pro-inflammatory factor levels decreased, and the anti-inflammatory factor levels increased. In contrast, mTOR overexpression lead to the opposite results.mTOR promotes inflammation by regulating the HIF signaling pathway during UC, and silencing mTOR may alleviate inflammation. An mTOR inhibitor is a potential therapeutic target for UC treatment.