Objective: To evaluate the therapeutic effect of Huangqin Decoction (HQD) on ulcerative colitis (UC) in mice and explore its mechanism.
Methods: Male Balb/c mice were randomly divided into normal control group, model group, mesalazine group (5-ASA, 200 mg/kg), and low-, medium-and high-dose HQD groups (2.275, 4.55 and 9.1 g/kg, respectively). With the exception of those in the normal control group, all the mice were exposed to 3% DSS solution in drinking water for 7 days to establish UC models. After treatment with the indicated drugs, the mice were assessed for colon injury and apoptosis using HE, AB-PAS and TUNEL staining, and the expression levels of inflammatory factors were detected with ELISA. Western blotting, immunohistochemistry and qRT-PCR were used to detect the changes in protein expressions associated with the intestinal chemical barrier, mechanical barrier and endoplasmic reticulum stress (ERS).
Results: HQD treatment significantly reduced DAI score and macro score of UC mice, decreased colonic epithelial cell apoptosis, lowered expressions of IL-6, TNF-α, IL-1β and IL-8, and enhanced the expressions of MUC2 and TFF3. HQD treatment also upregulated the protein expressions of claudin-1, occludin and E-cadherin, reduced the expressions of GRP78, CHOP, caspase-12 and caspase-3, decreased the phosphorylation levels of PERK, eIF2α and IRE1α, and increased the Bcl-2/Bax ratio in the colon tissues of UC mice.
Conclusion: HQD inhibits colonic epithelial cell apoptosis and improves intestinal barrier function in UC mice possibly by reducing ERS mediated by the PERK and IRE1α signaling pathways.
目的: 观察黄芩汤对小鼠溃疡性结肠炎（UC）细胞凋亡的影响并探讨其作用机制。
方法: 将雄性Balb/c小鼠随机分为：正常组、模型组、美沙拉嗪组（5-ASA，200 mg/kg）、黄芩汤低、中、高剂量组（HQDL，2.275 g/kg；HQDM，4.55 g/kg；HQDH，9.1 g/kg），8只/组。各组自由饮食，除正常组自由饮用无菌水外，其余各组小鼠自由饮用3% DSS溶液，持续7d以建立UC模型。取结肠组织采用HE、AB-PAS和TUNEL染色分别观察结肠损伤和细胞凋亡情况，采用ELISA法检测炎症因子表达变化；采用Western blotting、免疫组化和qRT-PCR法分别检测肠道化学屏障、机械屏障、内质网应激等相关指标的蛋白或基因表达变化。
结果: 与模型组相比，黄芩汤干预下的UC小鼠，DAI评分和宏观评分下降（P<0.01），TUNEL染色荧光强度下降（P<0.01）。促炎因子IL-6、TNF-α、IL-1β、IL-8表达减少（P<0.01），MUC2和TFF3的基因表达升高（P<0.05），Claudin-1、Occludin和E-cadherin的蛋白表达升高（P<0.05），GRP78、CHOP和Caspase-12的基因和蛋白表达下降（P<0.01）、PERK、eIF2α和IRE1α的磷酸化表达降低（P<0.05），Bcl-2/Bax蛋白表达比例升高（P<0.01）和Caspase-3的蛋白表达降低（P<0.01）。
结论: 黄芩汤能够抑制UC小鼠的细胞凋亡反应并改善肠道屏障功能，其机制可能与PERK和IRE1α信号通路介导的内质网应激有关。
Keywords: Huangqin Decoction; apoptosis; endoplasmic reticulum stress; ulcerative colitis.