袖状胃切除术调节GLP-1/DPP-4通路抑制肥胖症小鼠氧化应激诱导脂肪炎症的作用

Effect of sleeve gastrectomy in regulating the GLP-1/DPP-4 pathway to inhibit oxidative stress-induced adipose inflammation in obese mice

背景与目的:袖状胃切除术(SG)是治疗肥胖症的有效方法,但其产生疗效的机制仍未完全明确。胰高血糖素样肽1(GLP-1)和二肽基肽酶4(DPP-4)信号通路与肥胖症的慢性氧化应激状态以及脂肪炎症密切相关,但SG术的治疗作用是否影响该通路尚不清楚。因此,本研究探讨SG术对高脂饮食诱导肥胖症小鼠脂肪组织GLP-1/DPP-4通路、氧化应激及炎症反应的影响。方法:将30只小鼠用高脂饲养法建立肥胖症模型,另将10只用标准饲料饲养的小鼠作为正常对照组。将30只肥胖症模型小鼠随机均分为三组,分别行SG术(模型+SG组)和假手术(模型+假手术组)或不做任何处理(单纯模型组),术后各组小鼠给予标准饲料继续饲养4周,采集内脏脂肪组织标本,通过HE染色观察脂肪组织病理学变化,采用免疫组化及qRT-PCR方法分析脂肪组织中GLP-1及其受体GLP-1R、DPP-4、NADPH氧化酶4(Nox-4)、抗氧化酶[锰超氧化物歧化酶(MnSOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)]、巨噬细胞表面标志物(CD11b)、单核细胞/巨噬细胞表面标志物(CD68、F4/80)以及促炎因子[单核细胞趋化蛋白1(MCP-1)、IL-1β、IL-6、TNF-α]的表达。结果:HE染色结果显示,各肥胖症模型组小鼠脂肪组织相对于正常对照组均出现单核细胞浸润反应和炎症反应,但模型+SG组的以上反应弱于单纯模型组与模型+假手术组。免疫组化结果显示,与正常对照组比较,各肥胖症模型组小鼠脂肪组织中GLP-1与GLP-1R的表达降低,而DPP-4的表达增高,CD11b阳性细胞比例及Nox-4表达增加,但模型+SG组以上变化明显弱于单纯模型组与模型+假手术组,而后两组间以上变化无明显差异。qRT-PCR结果显示,与正常对照组比较,各肥胖症模型组小鼠脂肪组织中GLP-1与GLP-1R的mRNA表达降低,而DPP-4的mRNA表达增高(均P<0.05);CD68、F4/80的mRNA表达明显升高(均P<0.05)、Nox-4的mRNA表达水平升高,而MnSOD、GSH-Px及CAT的mRNA表达明显降低(均P<0.05);MCP-1、IL-1β、IL-6及TNF-α表达明显升高(均P<0.05),但模型+SG组以上指标的变化幅度均明显小于单纯模型组与模型+假手术组(均P<0.05),而后两组间以上指标的变化幅度均无明显差异(均P>0.05)。结论:SG术能够有效调节脂肪组织中GLP-1/DPP-4通路,抑制免疫反应、氧化应激及促炎因子的异常表达,从而改善脂肪组织炎症反应。

Background and Aims:Sleeve gastrectomy(SG)is an effective method for treating obesity,but the mechanisms through which it exerts its effects are not fully understood.The glucagon-like peptide-1(GLP-1)and dipeptidyl peptidase-4(DPP-4)signaling pathways are closely related to the chronic oxidative stress state and adipose inflammation associated with obesity.However,it remains unclear whether the therapeutic effects of SG impact this pathway.Therefore,this study investigates the effects of SG on the GLP-1/DPP-4 pathway,oxidative stress,and inflammatory response in the adipose tissue of high-fat diet-induced obese mice.Methods:Thirty mice were fed a high-fat diet to establish an obesity model,while another ten mice fed a standard diet were the normal control group.The 30 obese model mice were randomly divided into three groups to undergo SG operation(model+SG group),and sham operation(model+sham operation group),or to receive no treatment(simple model group),respectively.After surgery,all groups were fed a standard diet for 4 weeks.Visceral fat tissue samples were collected,and pathological changes in adipose tissue were observed using HE staining.Immunohistochemistry and qRT-PCR methods were used to analyze the expression of GLP-1 and its receptor GLP-1R,DPP-4,NADPH oxidase 4(Nox-4),antioxidant enzymes[manganese superoxide dismutase(MnSOD),glutathione peroxidase(GSH-Px),catalase(CAT)],macrophage surface markers(CD11b),monocyte/macrophage surface markers(CD68,F4/80),and pro-inflammatory factors[monocyte chemoattractant protein-1(MCP-1),IL-1β,IL-6,TNF-α]in the adipose tissue.Results:HE staining showed that all obesity model groups had monocyte infiltration and inflammatory responses in adipose tissue compared to the normal control group.However,these responses were weaker in the model+SG group than those in the simple model group and the model+sham operation group.Immunohistochemistry results showed that the expressions of GLP-1 and GLP-1R were decreased compared to the normal control group.In contrast,DPP-4 expression was increased,and the proportion of CD11b positive cells and Nox-4 expression increased in the adipose tissue of all obesity model groups.However,these changes were significantly weaker in the model+SG group than those in the simple model group and the model+sham operation group,with no significant differences between the latter two groups.qRT-PCR results showed that in all obesity model groups compared to the normal control group,the mRNA expressions of GLP-1 and GLP-1R were decreased,while the mRNA expression of DPP-4 was increased(all P<0.05);the mRNA expression of CD68,F4/80 significantly increased(all P<0.05),the mRNA expression of Nox-4 increased,while the mRNA expression of MnSOD,GSH-Px,and CAT significantly decreased(all P<0.05);MCP-1,IL-1β,IL-6,and TNF-αexpression significantly increased(all P<0.05).However,the magnitudes of changes in these variables were significantly smaller in the model+SG group compared to the simple model group and the model+sham operation group(all P<0.05).At the same time,there were no significant differences in the magnitudes of changes between the latter two groups(all P>0.05).Conclusion:SG operation can effectively regulate the GLP-1/DPP-4 pathway in adipose tissue and inhibit the immune responses,oxidative stress,and abnormal expression of pro-inflammatory factors,thereby improving the inflammatory response in adipose tissue.