右美托咪定上调HIF-1α抑制NLRP3炎性体的激活减轻糖尿病小鼠心肌缺血再灌注损伤

Dexmedetomidine Alleviates Myocardial Ischemia-reperfusion Injury in Diabetic Mice by up-regulating HIF-1αand Inhibiting the Activation of NLRP3 Inflammasome

目的:探讨右美托咪定(DEX)对糖尿病小鼠心肌缺血再灌注损伤的保护作用及可能分子机制。方法:将60只8周龄的SPF级C57BL小鼠高脂喂养6周,第7周通过腹腔注射链脲佐菌素(STZ)45 mg/kg/天,1次/天,连续5天,建立2型糖尿病模型,建模后采用随机数字表法分为假手术组(sham组)、缺血再灌注组(I/R组)、缺氧诱导因子-1α(HIF-1α)抑制剂2ME2组(2ME2组)、DEX组、DEX+2ME2组(DM组),每组12只。假手术组仅切开皮肤后缝合,其余四组开胸结扎冠状动脉左前降支,缺血60 min后松开结扎线结,再灌注120 min建立缺血再灌注损伤模型。于再灌注120 min时抽取小鼠腹主动脉血,ELISA检测血清肌钙蛋白I(cTnI)、白介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)的浓度,随后处死小鼠,分离左心室,HE染色观察心肌组织形态结构,Western blot检测HIF-1α、nod样受体蛋白3(NLRP3)的表达量,再灌注24 h时超声心动图评估心功能。结果:与sham组相比,I/R组、2ME2组、DEX组、DM组cTnI、IL-1β,TNF-α浓度明显升高,心肌组织结构紊乱,心肌纤维断裂增加,心肌细胞明显肿胀,炎性细胞浸润增加,心肌组织NLRP3表达量显著增加,每搏量(SV)、射血分数(EF)%、短轴缩短率(FS)%明显下降(P<0.05);与I/R组相比,DEX组、DM组HIF-1α表达量明显增加,NLRP3表达明显降低,cTnI、IL-1β,TNF-α浓度明显下降,心肌组织结构明显改善,炎性细胞浸润明显减少,SV,EF、FS明显升高(P<0.05);与DEX组相比,DM组HIF-1α表达量明显降低,NLRP3表达量明显增加,cTnI、IL-1β、TNF-α浓度明显增加,心肌组织结构紊乱,心肌纤维断裂增加,心肌细胞明显肿胀,炎性细胞浸润增加,SV,EF、FS明显降低(P<0.05)。结论:DEX可能通过上调心肌组织HIF-1α的表达,抑制NLRP3炎性体的激活,减轻心脏炎症反应,改善糖尿病小鼠心肌缺血再灌注损伤。

Objective:To investigate the protective effect of dexmedetomidine(DEX)on myocardial ischemia-reperfusion injury in diabetic mice and its possible molecular mechanism.Methods:Sixty 8-week-old SPF C57BL mice were fed with high fat for 6 weeks.At the 7th week,the type 2 diabetes model was established by intraperitoneal injection of streptozotocin(STZ)45 mg/kg/d once a day for 5 days.After modeling,the mice were randomly divided into sham operation group(sham group),ischemia-reperfusion group(I/R group),hypoxia-inducible factor-1α(HIF-1α)inhibitor 2ME2 group(2ME2 group),DEX group and DEX+2ME2 group(DM group),with 12 mice in each group.In sham group,the skin was only cut and sutured.In the other four groups,the left anterior descending coronary artery was ligated through thoracotomy,and the ligating wire was released after 60 minutes of ischemia,followed by 120 minutes of reperfusion to establish the ischemia-reperfusion injury model.Blood samples were collected from the abdominal aorta at 120 min of reperfusion for determination of serum concentrations of troponin I(cTnI),interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)by ELISA.Then the mice were sacrificed and left ventricles were isolated for observation of morphology and structure of myocardium by HE staining.The expression of HIF-1αand NOD-like receptor protein 3(NLRP3)was detected by Western blot.Cardiac function was assessed by echocardiography at 24 h of reperfusion.Results:Compared with sham group,the concentrations of cTnI,IL-1βand TNF-αwere significantly increased,myocardial tissue structure disorder,myocardial fiber rupture,myocardial cell swelling,inflammatory cell infiltration were significantly increased,the expression of NLRP3 in myocardial tissue was significantly increased,and stroke volume(SV),ejection fraction(EF)%and fractional shortening(FS)%were significantly decreased in I/R,2ME2,DEX and DM groups(P<0.05).Compared with I/R group,the expression of HIF-1αwas significantly increased,the expression of NLRP3 was significantly decreased,the concentrations of cTnI,IL-1βand TNF-αwere significantly decreased,myocardial tissue structure was significantly improved,inflammatory cell infiltration was significantly decreased,SV,EF and FS were significantly increased in DEX and DM groups(P<0.05).Compared with the DEX group,the expression of HIF-1αwas significantly decreased,the expression of NLRP3 was significantly increased,the concentrations of cTnI,IL-1βand TNF-αwere significantly increased,myocardial tissue structure disorder,myocardial fiber rupture,myocardial cell swelling,inflammatory cell infiltration were significantly increased,SV,EF and FS were significantly decreased in the DM group(P<0.05).Conclusion:DEX can alleviate myocardial I/R injury in diabetic mice by up-regulating HIF-1α,inhibiting the activation of NLRP3 inflammasome and reducing inflammatory response.