罗格列酮通过抑制肠系膜脂肪组织炎症改善三硝基苯磺酸(TNBS)诱导的小鼠结肠炎

Rosiglitazone ameliorates TNBS-induced colitis in mice by inhibiting inflammation of the mesenteric adipose tissues

目的探讨过氧化物酶体增殖物激活受体γ(PPARγ)激动剂罗格列酮(rosiglitazone)对2,4,6-三硝基苯磺酸(TNBS诱导的结肠炎小鼠的治疗作用及可能机制。方法选取雄性BALB/c小鼠20只建立TNBS结肠炎模型,造模成功后随机分为罗格列酮处理组及模型组,每组10只。罗格列酮处理组给予罗格列酮灌胃(0. 2 m L,[20 mg/(kg·d)]),模型组给予生理盐水(0. 2 m L/d)灌胃。处理6周后,处死所有小鼠。采用炎症性肠病疾病活动度指数(DAI)及HE染色结合Spencer结肠炎组织学评分评估两组小鼠肠道炎症程度及组织学改变,ELISA检测肠黏膜白细胞介素1β(IL-1β)、肿瘤坏死因子α(TNF-α)、IL-10水平及肠系膜脂肪组织IL-6、单核细胞趋化蛋白1(MCP-1)水平;脂肪组织HE染色后200倍光镜下拍照依据比例尺计算脂肪细胞直径;免疫组织化学染色法检测小鼠肠系膜脂肪组织F4/80阳性巨噬细胞浸润数量、脂肪细胞成熟标志物外周蛋白(peripherin)、脂连蛋白(adiponectin)及瘦素(leptin)水平。Western blot法检测小鼠肠系膜脂肪组织核因子κB(NF-κB)和信号通路中的NF-κBp65、磷酸化的NF-κBp65(p-NF-κBp65)、磷酸化的NF-κB抑制蛋白(p-IκB)及磷酸化的IκB激酶(p-IKK)的蛋白水平。结果罗格列酮处理后第5及6周,小鼠DAI评分显著低于模型组。同时,处理组小鼠肠黏膜IL-1β及TNF-α水平显著低于模型组,而IL-10水平显著高于模型组。与模型组小鼠相比,罗格列酮处理组小鼠肠系膜脂肪细胞直径及脂肪细胞成熟标志物perilipin水平均显著高于模型组。同时,罗格列酮处理组小鼠肠系膜脂肪组织巨噬细胞浸润数量及炎症介质IL-6、MCP-1水平均显著低于模型组。罗格列酮治疗显著促进处理组小鼠肠系膜脂肪细胞adiponectin的表达,而抑制leptin的水平。罗格列酮处理组小鼠肠系膜脂肪组织NF-κBp65、p-NF-κBp65、p-IKK及p-IκB蛋白水平均显著低于模型组。结论罗格列酮可显著抑制TNBS模型小鼠肠道炎症,可能与抑制肠系膜脂肪组织NF-κBp65通路有关。

Objective To evaluate the therapeutic effect and possible mechanism of PPARy agonist rosiglitazone on 2, 4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in mice.Methods Twenty male BALB/c mice were selected to establish TNBS-induced colitis model and were randomly divided into rosiglitazone treated group and model group with 10 rats in each group.Rosiglitazone group was treated with rosiglitazone(0.2mL,[20mg/(kg ·d)] )and model group with normal saline(0.2mL/d).After 6 weeks of administration,the mice were sacrificed.Inflammatory bowel disease disease activity index (DAI)and HE staining combined with Spencer colitis histological score were used to evaluate the degree of intestinal inflammation and histological changes in the two groups.ELISA was used to detect the levels of interleukin-1β(IL-1β), tumor necrosis factor alpha(TNF-α)and IL-10 in the intestinal mucosa,the levels of IL-6 and monocyte chemoattractant protein 1(MCP-1)in the mesenteric adipose tissues.The mean diameter of adipocytes in the mesenteric adipose tissues was calculated under light microscope after HE staining.The number of F4/80+macrophages and the expressions of peripherin,adiponectin and leptin in mesenteric adipose tissues were detected by immunohistochemical staining.The phosphorylation of NF-κBp65,IKK,IκB proteins in the mesenteric adipose tissues was detected by Western blot analysis. Results The DAI score of rosiglitazone group was significantly lower than that of model group at 5 and 6 weeks after rosiglitazone treatment.At the same time,the levels of IL-1β and TNF-α in the intestinal mucosa of the treated group were significantly lower than those in the model group,while the IL-10 levels were significantly higher in the treated group than in the model group.Compared with the model group,the mesenteric adipocyte diameter and the perilipin level of adipocyte maturation markers in rosiglitazone treated mice were significantly higher than those in model group.Meanwhile, the number of infiltration of macrophages in mesenteric adipose tissues of mice treated with rosiglitazone and the levels of inflammatory mediators IL-6 and MCP-1 were significantly lower than that of the model group.Rosiglitazone significantly promoted the expression of adiponectin and inhibited the expression of leptin in mesenteric adipocytes.The phosphorylation of NF-κBp65,IKK and IκB proteins in mesenteric adipose tissues of rosiglitazone treated mice was significantly lower than those of model group.Conclusion Rosiglitazone significantly inhibites intestinal inflammation in TNBS-induced colitis in mice, which may be related to the inhibition of NF-κBp65 pathway in mesenteric adipose tissues.