右美托咪定对缺氧/复氧心肌细胞的保护作用及机制研究

Protective effect and mechanism of dexmedetomidine on hypoxia-reoxygenated myocardial cells

目的探讨右美托咪定(Dex)对缺氧/复氧(H/R)心肌细胞的保护作用及机制。方法选取H9C2细胞构建H/R细胞损伤模型(H/R组),正常培养的细胞为对照组。采用Dex处理细胞24 h后进行H/R处理,纳入H/R+Dex组,将Vector、微小RNA(miR)-138-5p mimic质粒转染至H9C2细胞后采用H/R处理,分别定义为H/R+Vector组、H/R+miR-138-5p组。将Vector、miR-138-5p mimic质粒分别与MUT-SOX9、WT-SOX9载体结合后共同转染至H9C2细胞,得到的转染细胞分别纳入突变型(MUT)-SOX9+Vector组、MUT-性别决定区Y框蛋白9(SOX9)+miR-138-5p组、野生型(WT)-SOX9+Vector组及WT-SOX9+miR-138-5p组。采用细胞计数试剂盒8(CCK-8)检测细胞增殖;采用流式细胞术检测细胞凋亡;采用酶联免疫吸附法(ELISA)检测细胞上清液超氧化物歧化酶(SOD)、乳酸脱氢酶(LDH)、丙二醛(MDA)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平;采用实时荧光定量聚合酶链式反应(RT-qPCR)检测miR-138-5p表达;采用Weston blot检测TNF-α、IL-6、白细胞淋巴瘤-2(Bcl-2)、Bcl相关X蛋白(Bax)及SOX9的表达;采用荧光素酶报告实验检测miR-138-5p与SOX9的靶向关系。结果与对照组比较,H/R组细胞增殖活力、凋亡率、Bax、SOX9、MDA、LDH、TNF-α及IL-6表达量升高,Bcl-2、SOD及miR-138-5p表达量降低,差异有统计学意义(P<0.001)。与H/R组比较,H/R+Dex组细胞增殖活力、凋亡率、Bax、SOX9、MDA、LDH、TNF-α及IL-6表达量降低,Bcl-2、SOD及miR-138-5p表达量升高,差异有统计学意义(P<0.001)。与H/R+Vector组比较,H/R+miR-138-5p组细胞增殖活力、凋亡率、Bax、SOX9、MDA、LDH、TNF-α及IL-6表达量降低,Bcl-2、SOD及miR-138-5p表达量升高,差异有统计学意义(P<0.001)。H/R+miR-138-5p组细胞SOX9表达量低于H/R+Vector组,差异有统计学意义(P<0.05)。与WT-SOX9+Vector组比较,WT-SOX9+miR-138-5p组细胞SOX9表达量降低,差异有统计学意义(P<0.05);MUT-SOX9+Vector组与MUT-SOX9+miR-138-5p组细胞SOX9表达量差异无统计学意义(P>0.05)。结论Dex通过上调miR-138-5p的表达水平抑制SOX9的表达,减轻炎症反应和氧化应激反应,从而减轻H/R引起的心肌细胞损伤程度。

Objective To investigate the protective effect and mechanism of dexmedetomidine(Dex)on hypoxia-reoxygenated (H/R) cardiomyocytes.Methods H9C2 cells were selected to construct a H/Rcell injury model(H/Rgroup),and normal cultured cells were used as the control group.The cells treated with Dex for 24 h before H/R treatment were defined as H/R+Dex group.Vector and microRNA(miR)-138-5p mimic plasmids transfected into H9C2 cells after H/R treatment were defined as H/R+Vector group and H/R+miR-138-5p group.Vector and miR-138-5p mimic plasmids were co-transfected with MUT-SOX9 and WT-SOX9 vectors,and then transfected into H9C2 cells,which were defined as mutant type(MUT)-SOX9+Vector group,MUT-sex-determining region Y box protein 9(SOX9)+miR-138-5p group,WT-SOX9+Vector group and wild type(WT)-SOX9+miR-138-5p group.Cell Counting Kit-8(CCK-8)was conducted to perform cell proliferation;flow cytometry was conducted to perform apoptosis;enzyme-linked reaction adsorption assay(ELISA)was conducted to perform cell supernatant superoxide dismutase(SOD),lactate dehydrogenase(LDH),malondialdehyde(MDA),tumor necrosis factor-α(TNF-α),and interleukin-6(IL-6)levels;the real-time fluorescence quantitative polymerase chain reaction(RT-qPCR)was conducted to perform miR-138-5p expression;Weston blot was conducted to perform TNF-α,IL-6,leukocyte lymphoma-2(Bcl-2),and Bcl-related X protein(Bax)and SOX9 expression;the luciferase reporter assay was performed to detect the targeting relationship between miR-138-5p and SOX9.Results Compared with the control group,cell proliferation viability,apoptosis rate,expression of Bax,SOX9,MDA,LDH,TNF-α and IL-6 were increased in the H/R group,and expression of Bcl-2,SOD and miR-138-5p were decreased(P<0.05).Compared with the H/R group,cell proliferation viability,apoptosis rate,Bax,SOX9,MDA,LDH,TNF-α and IL-6 expression were decreased in the H/R+Dex group,and Bcl-2,SOD and miR-138-5p expression were increased in the H/R+Dex group(P<0.001).Compared with the H/R+Vector group,cell proliferation viability,apoptosis rate,Bax,SOX9,MDA,LDH,TNF-α and IL-6 expression were decreased in the H/R+miR-138-5p group,and Bcl-2,SOD and miR-138-5p expression were increased(P<0.05).The expression of SOX9 in H/R+miR-138-5p group was lower than that in the H/R+Vector group(P<0.001).Compared with WT-SOX9+Vector group,the expression level of SOX9 in WT-SOX9+miR-138-5p group was decreased(P<0.05).There was no significant difference in the expression of SOX9 between the MUT-SOX9+Vector group and the MUT-SOX9+miR-138-5p group(P>0.05).Conclusion Dex inhibits the expression of SOX9 by up-regulating the expression level of miR-138-5p,alleviates inflammatory response and oxidative stress response,thereby alleviating the degree of myocardial cell damage caused by H/R.