促红细胞生成素预处理在心肌缺氧复氧损伤中的抗炎作用

Anti-inflammatory effect of erythropoietin pretreatment in myocardium exposed to hypoxia-reoxygenation injury

目的观察促红细胞生成素(erythropoietin,EPO)预处理在大鼠心肌缺氧复氧损伤(hypoxia/reoxygenation,H/R)中的抗炎作用并探讨其可能机制。方法Wistar成年雄性大鼠60只,分为对照组,EPO预处理组(EPO组),每组30只,EPO组大鼠经腹腔注射5000U/kg重组人促红细胞生成素(recombinant human erythropoietin,RHuEPO),对照组注射同体积生理盐水。2组各15只大鼠于给药24h后,采取心肌,以DNA末端转移酶标记法(TUNEL法)检测心肌细胞凋亡,免疫组化检测凋亡效应酶胱天蛋白酶-3(caspase-3)、炎性细胞因子TNF-α蛋白表达水平,凝胶电泳迁移率实验(elec-trophoretic mobility shift assay,EMSA)检测核因子-κB(nuclear factor-κB,NF-κB)DNA结合活性,其余15只大鼠置于常压缺氧环境中(O27%)12h后,移至常压常氧环境中2h,予H/R损伤,采取心肌,检测以上各指标。结果H/R损伤前2组心肌细胞凋亡率,caspase-3、TNF-α蛋白表达差异无统计学意义(P>0.05),EPO组心肌NF-κB DNA结合活性显著高于对照组(P<0.05,P<0.01)。H/R损伤后2组心肌细胞凋亡率,caspase-3、TNF-α蛋白表达水平,NF-κB DNA结合活性显著高于损伤前(P<0.01),EPO组的心肌细胞凋亡率,caspase-3、TNF-α蛋白表达水平,NF-κB DNA结合活性显著低于对照组(P<0.05,P<0.01)。结论EPO预处理在心肌H/R损伤中具有抑制NF-κB活化及炎性细胞因子TNF-α表达的抗炎作用;这一作用可能与NF-κB激活的负反馈机制有关。

Objective This study is to explore the anti-inflammatory effect of EPO pretreatment in myocardium exposed to H/R injury. Methods 60 male adult Wistar rats were randomly divided into 2 groups：eontrol group and EPO pretreatment group （EPO group）. The rats in EPO group received peritoneal injection of 5000U/kg PHuEPO, and control group received the peritoneal injection of the same volume of saline. 24 hours after the pretreatment,myoeardium was collected from 15 rats in each group. Apoptotic ratio of cardiomyocytes was detected by TUNEL. Expression of caspase-3 and TNF-α was analyzed by immunostaining. EMSA was used to analyze NF-κB DNF-binding activity. The other 15 rats in each group were exposed to hypoxia （ O2 7% ）for 12 hours and then to normoxia for 2 hours （reoxygenation）. All the markers mentioned above were assayed then. Results There was no significant difference in apoptotic ration of eardiomyoeytes and expression of caspase-3 and TNF-α protein between the 2 groups before H/R （P〉0. 05 ）. NF-κB DNA-binding activity was elevated in EPO group, compared to control group （P〈0. 01 ）. After H/R, apoptotie ratio of cardiomyoctyes, expression of easpase-3 and TNF-α protein and NF-κB DNA-binding activity in beth groups increased significantly compared to before H/R （ P〈0. 05, P〈0.01 ）. Apoptosis of eardiomyoetyes, elevation of expression of easpase-3 and TNF-α protein and activation of NF-κB were inhibited in EPO group（ P〈0. 05, P〈0.01 ）. Conclusion EPO pretreatment can inhibit activation of NF-κB and expression of TNF-α protein in myocardium exposed to H/R injury,producing anti-inflammatory effect. This effect might be associated with the negative feed-back regulation of NF-κB pathway.