Type-17 immune response, mediated mainly by IL-17, plays a critical role in ulcerative colitis. Previously, we showed that madecassic acid (MA), the main active ingredient of Centella asiatica herbs for anti-colitis effect, ameliorated dextran sulfate sodium (DSS)-induced mouse colitis through reducing the level of IL-17. Here, we explore the effect of MA on the activation of γδT17 cells, an alternative source of IL-17 in colitis. In DSS-induced colitis mice, oral administration of MA decreased the number of γδT17 cells and attenuated the inflammation in the colon, and the anti-colitis effect of MA was significantly counteracted by redundant γδT17 cells, suggesting that the decrease in γδT17 cells is important for the anti-colitis effect of MA. In vitro, MA could inhibit the activation but not the proliferation of γδT17 cells at concentrations without evident cytotoxicity. Antibody microarray profiling showed that the inhibition of MA on the activation of γδT17 cells involved PPARγ–PTEN/Akt/GSK3β/NFAT signals. In γδT17 cells, MA could reduce the nuclear localization of NFATc1 through inhibiting Akt phosphorylation to promote GSK3β activation. Moreover, it was confirmed that MA inhibited the Akt/GSK3β/NFATc1 pathway and the activation of γδT17 cells through activating PPARγ to increase PTEN expression and phosphorylation. The correlation between activation of PPARγ, decrease in γδT17 cell number, and amelioration of colitis by MA was validated in mice with DSS-induced colitis. In summary, these findings reveal that MA inhibits the activation of γδT17 cells through PPARγ–PTEN/Akt/GSK3β/NFAT pathway, which contributes to the amelioration of colitis.

主要由 IL-17 介导的 17 型免疫反应在溃疡性结肠炎中起关键作用。之前，我们展示了积雪草的主要活性成分羟基积雪草酸 (MA)具有抗结肠炎作用的草药，通过降低 IL-17 的水平来改善葡聚糖硫酸钠 (DSS) 诱导的小鼠结肠炎。在这里，我们探讨了 MA 对 γδT17 细胞活化的影响，γδT17 细胞是结肠炎中 IL-17 的替代来源。在 DSS 诱导的结肠炎小鼠中，口服 MA 减少了 γδT17 细胞的数量并减轻了结肠炎症，并且 MA 的抗结肠炎作用被多余的 γδT17 细胞显着抵消，表明 γδT17 细胞的减少很重要MA的抗结肠炎作用。在体外，MA在没有明显细胞毒性的浓度下可以抑制γδT17细胞的活化但不能抑制其增殖。抗体微阵列分析表明，MA 对 γδT17 细胞活化的抑制涉及 PPARγ-PTEN/Akt/GSK3β/NFAT 信号。在 γδT17 细胞中，MA 可以通过抑制 Akt 磷酸化促进 GSK3β 活化来减少 NFATc1 的核定位。此外，证实MA通过激活PPARγ增加PTEN表达和磷酸化来抑制Akt/GSK3β/NFATc1通路和γδT17细胞的活化。PPARγ 激活、γδT17 细胞数量减少和 MA 改善结肠炎之间的相关性在 DSS 诱导的结肠炎小鼠中得到验证。总之，这些发现表明MA通过PPARγ-PTEN/Akt/GSK3β/NFAT途径抑制γδT17细胞的活化，这有助于结肠炎的改善。证实MA通过激活PPARγ增加PTEN表达和磷酸化来抑制Akt/GSK3β/NFATc1通路和γδT17细胞的活化。PPARγ 激活、γδT17 细胞数量减少和 MA 改善结肠炎之间的相关性在 DSS 诱导的结肠炎小鼠中得到验证。总之，这些发现表明MA通过PPARγ-PTEN/Akt/GSK3β/NFAT途径抑制γδT17细胞的活化，这有助于结肠炎的改善。证实MA通过激活PPARγ增加PTEN表达和磷酸化来抑制Akt/GSK3β/NFATc1通路和γδT17细胞的活化。PPARγ 激活、γδT17 细胞数量减少和 MA 改善结肠炎之间的相关性在 DSS 诱导的结肠炎小鼠中得到验证。总之，这些发现表明MA通过PPARγ-PTEN/Akt/GSK3β/NFAT途径抑制γδT17细胞的活化，这有助于结肠炎的改善。