Objective: To elucidate the pathogenic role of leukotriene B4 (LTB4) in increased pulmonary microvascular endothelial cell permeability induced by one lung ventilation (OLV) in rabbits.
Methods: Forty-eight healthy Japanese white rabbits were randomly divided into control group (group C), saline pretreatment group (group S), bestatin (a leukotriene A4 hydrolase (LTA4H) inhibitor) plus saline pretreatment group (group B), OLV group (group O), saline pretreatment plus OLV group (group SO) and bestatin plus saline pretreatment with OLV group (group BO). ELISA was used to detect LTB4 content in the lung tissues, and LTA4H and phospholipase Cεl (PLCEl) expressions were examined by Western blotting and quantitative PCR. The wet/dry weight (W/D) ratio of the lung, lung permeability index and the expressions of myosin light chain kinase (MLCK) protein and mRNA in the lung tissues were determined to evaluate the permeability of the pulmonary microvascular endothelial cells (PMVECs). The severities of lung injury were evaluated by lung histomorphological scores.
Results: No significant differences were found among groups C, S and B except that LTA4H expressions was significantly lower in group B than in groups C and S (P<0.05). OLV significantly increased the expressions of LTA4H (P<0.05) and resulted in LTB4 overproduction in the lungs (P<0.05) accompanied by significantly enhanced PLCE1 expression and PMVEC permeability (P<0.05). Pretreatment with bestatin, significantly reduced the expression of LTA4H and LTB4 production (P<0.05) and down-regulated the expression of PLCE1 in the lungs of the rabbits receiving OLV (P<0.05).
Conclusion: Bestatin plays a protective role in OLV-induced rabbit lung injury by downregulating LTA4H to reduce the production of LTB4 in the lungs. LTB4 can increase PMVEC permeability by up-regulating PLCE1 expression in rabbits with OLV-induced lung injury.
目的: 观察运用乌苯美司减少单肺通气(OLV)兔肺内白三烯B4(LTB4)生成对肺组织磷脂酶Cεl(PLCE l)表达变化的影响，阐明LTB4在OLV致肺微血管内皮细胞(PMVEC)通透性增加中的作用机制。
方法: 48只健康日本大耳白兔随机均分为：对照组(C组)、溶剂(生理盐水)预处理组(S组)、(乌苯美司+生理盐水)预处理组(B组)、OLV组(O组)、生理盐水预处理+OLV组(SO组)和(乌苯美司+生理盐水)预处理+OLV组(BO组)。ELISA检测肺内LTB4含量。Western blotting和定量PCR分别用于检测白三烯A4水解酶(LTA4H)和PLCE1蛋白及各自mRNA表达水平。以肺通透性指数、肺湿/干(W/D)比值和肌球蛋白轻链激酶(MLCK)蛋白及mRNA表达水平反映PMVEC通透性，并通过肺组织形态学评分对肺损伤的严重程度进行评价。
结果: 除LTA4H表达水平在B组明显下降外(P < 0.05)，C组、S组和B组其它各检测指标均无显著性差异；OLV兔肺组织LTA4H表达水平上调(P < 0.05)，肺内LTB4生成增多(P < 0.05)，同时伴有PLCE1表达水平、PMVEC通透性和肺组织学评分的显著增加(P < 0.05)。生理盐水预处理对OLV实验动物上述指标变化无显著影响；乌苯美司预处理可显著抑制LTA4H表达(P < 0.05)，减少OLV实验动物肺内LTB4生成(P < 0.05)，下调肺组织PLCE1表达(P < 0.05)，明显减轻OLV诱导的PMVEC通透性增加和肺损伤(P < 0.05)。
结论: 乌苯美司可通过下调OLV兔LTA4H表达，减少肺内LTB4生成，继而发挥抗OLV致肺损伤保护作用。LTB4致OLV兔PMVEC通透性增加的作用机制与其上调PLCE1表达有关。