The effect of 6-gingerol on inflammatory response and Th17/Treg balance in DSS-induced ulcerative colitis mice

Background: Ulcerative colitis (UC) is a non-specific chronic intestinal inflammatory disease with unclear etiology. Previous studies have suggested that the imbalance of Treg/Thl7 cells may be involved in the development of UC. It was found that 6-gingerol can alleviate the intestinal inflammatory damage and improve the weight loss of colitis mice. However, whether 6-gingerol can regulate the balance of Th17/Treg cells and inhibit the intestinal inflammatory response remains to be clarified. Methods: In this study, a dextran sulfate sodium (DSS)-induced colitis mouse model was established, and the effects of 6-gingerol on cytokines and the balance of Th17/Treg cells were observed usingserial assays, including enzyme-linked immunosorbent assay (ELISA), quantitative real time-polymerase chain reaction (qPCR), and Western blotting. Results: DSS caused the damage of bowel tissue and a 100% weight loss rate in colitis mice. The treatment of 6-gingerol can significantly relieve bowel damage and reduce incidence of weight loss to 16.7% at a low or high dose (P<0.05), which was similar to the therapeutic effect of mesalazine. It was found that DSS can up-regulate the mRNA levels of IL-6 and IL-17 in serum (by qPCR), and the serum and bowel levels of IL-6 and IL-17 (by ELISA); these levels were significantly different from those of the blank group (P<0.05). Furthermore, 6-gingerol was found to inhibit the increase of mRNA levels and serum and bowel levels of IL-6 and IL-17 induced by DSS, which is similar with mesalazine. It was also found that DSS can down-regulate the mRNA level of IL-10 in serum, along with the serum and bowel level of IL-10, with this being significantly different from the levels of the blank group (P<0.05). 6-gingerol could also inhibit the decrease of mRNA levels and serum and bowel levels of IL-10 induced by DSS, which is also similar to mesalazine. In addition, DSS could increase Th17 cell count and decrease Treg cell count in blood, with significant difference from that of the blank group (P<0.05). 6-gingerol could significantly (P<0.05) inhibit the increase of Th17 cells and the decrease of Treg cells induced by DSS, which is similar to the effect of mesalazine. The detection of expression levels of transcription factors RORγT for Th17 and FOXP3 for Treg at both mRNA and protein levels showed that DSS can up-regulate the mRNA and protein levels of RORγT, and down-regulate the mRNA and protein levels of FOXP3. Furthermore, 6-gingerol could significantly (P<0.05) inhibit the up-regulation of RORγT mRNA and protein, and the down-regulation of FOXP3 mRNA and protein induced by DSS, which is similar to the effect of mesalazine. Conclusions: 6-gingerol showed efficacy in the treatment of DSS-induced UC in mice, by regulating the cell balance of Th17/Treg, and by relieving inflammatory responses both systematically and locally.