白三烯B4在“肺保护性”通气致肺损伤中的作用机制  

Pathogenic role leukotriene B4 in lung injury induced by lung-protective mechanical ventilation in rabbits

作　　者：袁凌跃 李江[1] 杨泳[3] 郭欣[1] 刘星玲[1] 李丽莎[1] 朱晓燕 刘睿[1] YUAN Lingyue;LI Jiang;YANG Yong;GUO Xin;LIU Xingling;LI Lisha;ZHU Xiaoyan;LIU Rui(Department of Anesthesiology,First People's Hospital of Yunnan Province,Kunming 650032,China;Department of Anesthesiology,Third People's Hospital of Yunnan Province,Kunming 650011,China;Experimental Center of Medical Function,Kunming Medical University,Kunming 650500,China)

机构地区：[1]云南省第一人民医院麻醉科,云南昆明650032 [2]云南省第三人民医院麻醉科,云南昆明650011 [3]昆明医科大学医学机能实验中心,云南昆明650500

出　　处：《南方医科大学学报》2020年第10期1465-1471,共7页Journal of Southern Medical University

基　　金：国家自然科学基金地区基金项目(81760018);云南省科技厅-昆明医科大学联合专项(2017FE467-110);云南省卫生科技计划项目(2018NS0244)。

摘　　要：目的探讨白三烯B4(LTB4)在“肺保护性”机械通气(LPMV)致肺损伤中的作用机制。方法32只健康日本大耳白兔随机平均分为:溶剂预处理+假手术组(S组)、乌苯美司(白三烯A4水解酶抑制剂)预处理+假手术组(BS组)、溶剂预处理+LPMV组(PM组)和乌苯美司预处理+LPMV组(BPM组)。BS组和BPM组先实施连续5 d的乌苯美司8 mg/(kg·d)灌胃预处理,S组和PM组则在相同时间点灌胃给予同等容积的溶剂。乌苯美司或溶剂预处理结束后,对PM组和BPM组实验动物实施时长为5 h的LPMV:潮气量(VT)=8 mL/kg,呼气末正压(PEEP)=5 cm H2O,吸气时间:呼气时间(I∶E)=1∶2,吸入氧浓度(FiO2)=0.5,调整呼吸频率(RR)维持呼末CO2在35~45 mmHg范围内;S组和BS组则保留自主呼吸。酶联免疫法用于检测实验动物肺组织LTB4和环一磷酸腺苷(cAMP)含量;肺组织cAMP含量、蛋白激酶A(PKA)蛋白表达水平和活化Rap1蛋白(Rap1-GTP)/总Rap1蛋白比值分别用于反映cAMP/PKA和Rap1信号通路活性变化情况;用肺通透性[肺通透性指数和肺湿/干(W/D)重比值]、肺炎症反应[支气管肺泡灌洗液(BALF)中多形核白细胞(PMN)计数和肺组织髓过氧化物酶(MPO)活性]和肺组织形态学评分对肺损伤的严重程度进行判断。结果S组与BS组实验动物各检测指标无显著差异;除肺组织学评分无显著差异外,PM组和BPM组实验动物其余各指标均显著增高于S组(P<0.05);与PM组相比,BPM组实验动物肺内LTB4生成明显减少(P<0.05),cAMP/PKA和Rap1信号通路活性进一步上调(P<0.05),肺炎症反应与肺通透性增加明显减轻(P<0.05)。结论LPMV会造成实验动物肺内LTB4大量生成继而诱发肺炎症反应和肺通透性增加,LTB4在其中的作用机制与下调cAMP/PKA和Rap1信号通路活性有关;乌苯美司可通过抑制肺内LTB4的生成发挥抗LPMV诱导的肺炎症反应和肺通透性增加保护作用。Objective To elucidate the pathogenic role of leukotriene B4(LTB4)in pulmonary hyper-permeability and inflammation induced by lung-protective mechanical ventilation(LPMV)in rabbits.Methods Thirty-two healthy Japanese white rabbits were randomized into 4 groups for treatment with vehicle or bestatin(a leukotriene A4 hydrolase inhibitor that inhibits LTB4 production)administered intragastrically at the daily dose of 8 mg/kg for 5 days,followed by sham operation(group S and group BS,respectively,in which the rabbits were anesthetized only)or LPMV(group PM and group BPM,respectively,in which the rabbits received ventilation with 50%oxygen at a tidal volume of 8 mL/kg for 5 h).The concentrations of LTB4 and cyclic adenosine monophosphate(cAMP)in the lung tissues were analyzed by ELISA.cAMP content,protein kinase A(PKA)protein expression and the Rap1-GTP protein to total Rap1 protein ratio were determined to assess the activities of cAMP/PKA and Rap1 signaling pathways.The lung injury was evaluated by assessing lung permeability index,lung wet/dry weight ratio,polymorphonuclear leukocyte(PMN)count in bronchoalveolar lavage fluid(BALF),pulmonary myeloperoxidase(MPO)activity and lung histological scores.Results None of the examined parameters differed significantly between group S and group BS.All the parameters with the exception of lung histological score increased significantly in group PM and group BPM as compared to those in group S(P<0.05).Compared with those in PM group,the rabbits in group BPM showed significantly reduced LTB4 production in the lungs(P<0.05),up-regulated cAMP/PKA and Rap1 signaling pathway activities(P<0.05),and alleviated lung hyper-permeability and inflammation(P<0.05).Conclusion LPMV can induce LTB4 overproduction to down-regulate cAMP/PKA and Rap1 signaling pathways in the lungs of rabbits,which results in lung hyper-permeability and inflammation.Bestatin can inhibit LTB4 production in the lungs to protect against LPMV-induced lung hyper-permeability and inflammation.

关 键 词：机械通气 肺损伤 白三烯B4 环一磷酸腺苷/蛋白激酶A信号通路 环一磷酸腺苷/Rap1信号通路 

分 类 号：R965[医药卫生—药理学]