黄芩汤对溃疡性结肠炎模型小鼠NLRP3/Caspase-1通路的影响

Effects of Huangqin Tang on NLRP3/Caspase-1 pathway in mice model of ulcerative colitis

探讨黄芩汤(HQT)对硫酸葡聚糖钠盐(dextran sulfate, DSS)诱导的溃疡性结肠炎(ulcerative colitis, UC)模型小鼠NLRP3/Caspase-1信号通路的影响。将C57BL/6J小鼠随机分为空白组,模型组(DSS组),黄芩汤低(HQT-L组)、中(HQT-M组)、高(HQT-H组)剂量组,西药美沙拉嗪组(西药组),建立小鼠UC模型。造模成功后,HQT-L组、HQT-M组、HQT-H组和西药组分别给予低、中、高剂量的黄芩汤和美沙拉嗪混悬液灌胃,空白组和DSS组分别给予等体积的蒸馏水灌胃,给药10 d后,测定各组小鼠体质量、疾病活动指数(DAI)评分、结肠组织病理学评分,采用ELISA法测定血清白细胞介素6(interleukin-6,IL-6)、白细胞介素10(interleukin-10,IL-10)、白细胞介素1β(interleukin-1β,IL-1β)、肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)含量,实时荧光定量PCR(quantitative real-time, RT-qPCR)法测定结肠组织NLRP3、Caspase-1 mRNA的表达,免疫组化法检测结肠组织NLRP3、Caspase-1蛋白表达情况。结果显示,与空白组相比,DSS组小鼠体质量明显下降,DAI评分、结肠组织病理学评分明显增高;与DSS组相比,HQT各组及西药组的DAI评分明显改善,其中以HQT-M组、HQT-H组及西药组改善较为显著(P<0.05);HQT各组及西药组的结肠组织病理学评分明显下降,其中以HQT-M组、HQT-H组及西药组改善较为显著(P<0.05)。此外,与空白组相比,DSS组结肠组织中NLRP3、Caspase-1表达明显增多,同时小鼠血清中IL-6、IL-1β、TNF-α含量明显增高,IL-10含量明显降低;与DSS组小鼠相比较,HQT各组与西药组结肠组织中NLRP3、Caspase-1表达明显降低,而HQT各组和西药组的血清IL-6、IL-1β、TNF-α含量明显降低,IL-10含量显著升高,且HQT-H组及西药组改善最为显著(P<0.01)。综上,黄芩汤可能通过调节NLRP3/Caspase-1经典细胞焦亡途径,降低结肠组织中NLRP3、Caspase-1的表达,减少血清中IL-6、IL-1β、TNF-α的表达,增加IL-10的表达,从而改善DSS小鼠的肠道损伤症状及肠黏膜的炎症浸润,发挥治疗作用。

The aim of this study was to explore the effects of Huangqin Tang(HQT) on the NLRP3/Caspase-1 signaling pathway in mice with DSS-induced ulcerative colitis(UC). C57BL/6J mice were randomly divided into a blank group, a model group(DSS group), and low-, medium-and high-dose HQT groups(HQT-L, HQT-M, and HQT-H), and western medicine mesalazine group(western medicine group). The UC model was induced in mice. Subsequently, the mice in the HQT-L, HQT-M, HQT-H groups, and the western medicine group were given low-, medium-, high-dose HQT, and mesalazine suspension by gavage, respectively, while those in the blank and DSS groups were given an equal volume of distilled water by gavage. After 10 days of administration, the body weight, DAI scores, and colonic histopathological score of mice in each group were determined. The levels of IL-6, IL-10, IL-1β, and TNF-α in serum were determined by ELISA. The mRNA expression of NLRP3 and Caspase-1 in colon tissues was determined by RT-qPCR. The protein expression of NLRP3 and Caspase-1 in colon tissues was detected by immunohistochemistry. The results showed that compared with the blank group, the DSS group showed decreased body weight of mice and increased DAI scores and intestinal histopathological score. Compared with the DSS group, the HQT groups and the western medicine group showed improved DAI scores, especially in the HQT-M, HQT-H, and the western medicine groups(P<0.05). The intestinal histopathological scores of the HQT groups and the western medicine group significantly decreased, especially in the HQT-M, HQT-H, and the western medicine groups(P<0.05). In addition, compared with the blank group, the DSS group showed elevated expression of NLRP3 and Caspase-1 in colon tissues, increased serum levels of IL-6, IL-1β, and TNF-α, and decreased IL-10 level. Compared with the DSS group, the HQT groups and the western medicine group displayed decreased expression of NLRP3 and Caspase-1 in colon tissues, reduced serum levels of IL-6, IL-1β, and TNF-α, and increased IL-10 level. The improvement was the most significant in the HQT-H group and the western medicine group(P<0.01). In conclusion, HQT may reduce the expression of NLRP3 and Caspase-1 in colon tissues, reduce the se-rum levels of IL-6, IL-1β, and TNF-α, and increase the expression of IL-10 by regulating the classic pyroptosis pathway of NLRP3/Caspase-1, thereby improving the symptoms of intestinal injury and inflammatory infiltration of intestinal mucosa in DSS mice to achieve its therapeutic effect.