Nicotine protects against ulcerative colitis through regulating microRNA-124 and STAT3 / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE Although it is generally believed that nicotine accounts for the beneficial effect of smoking on ulcerative colitis, the underlying mechanisms remain not well- understood. Our previous finding that nicotine inhibits inflammatory responses through inducing miRNA-124 prompted us to ask whether the miRNA is involved in the protective action of nicotine on UC. METHODS MiR-124 expression in colon tissues and cells was determined by q-PCR and in situ hybridization. The effect of miR-124 on protective role of nicotine in ulcerative colitis was evaluated in DSS-treated mice and IL-6-treated Caco-2 colon epithelial cells. Expression of p-STAT3/STAT3 was detected by immuno?histochemistry and Western blot analysis. RESULTS miR- 124 expression is upregulated in colon tissues from patients and DSS- induced colitis. Nicotine treatment further elevated miR- 124 level in colon tissues of the mice, in infiltrated lymphocytes and epithelial cells, and augmented miR- 124 expression in lymphocytes isolated from human ulcerative colon tissues. Administration of nicotine also reduced weight loss, improved DAI and decreased HE score in DSS-induced colitis. Moreover, knock?down of miR-124 in vivo significantly diminished the beneficial effect of nicotine, and in vitro on IL-6-treated Caco-2 colon epithelial cells. Further analysis indicated that nicotine inhibited STAT3 activation in vivo and in IL-6-treated Caco-2 colon epithelial cells and Jurkat human T lymphocytes, in which miR-124 knockdown led to increased activation of STAT3. CONCLUSION These data indicated that nicotine exerts its protective action in UC through inducing miR-124 and its effect on STAT3, suggesting that the miR-124/STAT3 system is a potential target for the therapeutic intervention of UC.