intermedin对大鼠肾脏缺血再灌注损伤的保护作用及其机制

目的 观察intermedin（IMD）对大鼠肾脏缺血再灌注损伤（IRI）的保护作用并探讨其机制。 方法 健康雄性Wistar大鼠24只随机分为对照组、IRI组、转空质粒组、转IMD质粒组。动物右肾切除后，用超声微泡技术将质粒转染入肾脏，1周后制作肾脏IRI模型。PAS染色观察肾脏病理损伤，比色法检测肾组织超氧化物岐化酶（SOD）、髓过氧化物酶（MPO）和天冬氨酸半胱氨酸蛋白酶3（caspase-3），以及脂质过氧化物丙二醛（MDA）含量。免疫组织化学方法检测细胞间黏附分子1（ICAM-1）、P选择素及内皮素1（ET-1）表达。TUNEL染色检测肾组织细胞凋亡。 结果 PAS染色结果显示，IRI组肾小管及间质病理损伤显著重于对照组（P < 0.01）；转IMD组肾组织病理损伤则显著轻于IRI组（P < 0.01）。IRI组肾组织SOD活性显著低于对照组（P < 0.05），MPO活性、活性caspase-3、MDA含量及ICAM-1、P选择素和 ET-1表达均显著高于对照组（均P < 0.01）；转IMD组SOD活性显著高于IRI组（P < 0.05），MPO活性、活性caspase-3、MDA含量及ICAM-1、P选择素和ET-1表达均显著低于IRI组（均P < 0.01）。TUNEL染色显示，IRI组肾组织凋亡细胞数显著高于对照组（34.83%±8.75%比3.33%±0.47%，P < 0.01）；转IMD组肾组织凋亡细胞数（20.67%±7.71%）则较IRI组显著减轻（P < 0.01）。转空质粒组和IRI组以上指标差异均无统计学意义。 结论 IMD能减轻肾脏IRI，其机制至少部分与抑制氧自由基生成、炎细胞浸润及炎性因子ICAM-1、P选择素生成、ET-1生成、细胞凋亡有关，从而减轻肾组织局部氧化应激反应产生的活性氧。

Protective effect of intermedin on renal ischemia reperfusion injury and its mechanism

Objective To investigate the protective effect of intermedin(IMD) on renal ischemia reperfusion injury(IRI) and its mechanism. Methods A total of twenty-four male Wistar rats were randomly divided into four groups: control group, IRI group, empty plasmid group and IMD group. After remove of right kidney, plasmid was transfected into the kidney by ultrasonic microbubbles technology, and IRI model was made after 1 week. Renal pathology was observed by PAS staining. Renal tissue superoxide dismutase (SOD), myeloperoxidase (MPO), caspase-3 activity, and malondialdehyde (MDA) content were detected by colorimetric method. The intercellular cell adhesion molecule-1(ICAM-1), endothelin 1(ET-1) and P-selection expression of renal tissue were detected by immunohistochemical method. Apoptosis of renal tubular cell was detected by TUNEL. Results Compared with control group, tubulointerstitial pathological injury was significant aggravated in IRI group(P<0.01); compared with IRI group, IMD pretreatment significantly alleviated the degree of renal injury(P<0.01). Compared with control group, in IRI group, SOD activity was significantly decreased (P<0.05), MPO activity, caspase-3 activity, MDA production and the expression of ICAM-1, P-selection, ET-1 were increased significantly (all P< 0.01). Compared with IRI group, IMD pretreatment significantly increased SOD activity (P<0.05), decreased the MPO activity, caspase-3 activity, MDA production and the expression of ICAM-1, P-selection, ET-1(all P<0.01). The apoptosis rate of renal tubular epithelial cells in IRI group was significantly higher than that in control group (34.83%±8.75% vs 3.33%±0.47%, P<0.01), while the apoptosis rate of IMD group (20.67%±7.71%) was significantly lower than that of IRI group. There was no difference of above indexes between empty plasmid group and IRI group. Conclusions IMD pretreatment protects against renal IRI. The mechanism may be at least partly related to the clearance of oxygen free radicals, the improvement of lipid peroxidation, inflammatory cell infiltration and cell apoptosis, leading to the decrease of the production of reactive oxygen species caused by oxidative stress.