中性粒细胞和炎性介质在大鼠肠缺血再灌注后肺损伤中的作用

Roles of neutrophils and inflammatory mediators in lung injury induced by intestinal ischemia-reperfusion in rats

目的:探讨中性粒细胞(PMN)扣押和炎性介质对大鼠全肠道缺血再灌注(GIR)后肺损伤的影响及可能机制。方法:36只Wister大鼠随机分为缺血前30min和再灌注后(POR)3、6、24、48、72h共6组(n=6),采用夹闭肠系膜前动脉(时间60min)技术复制GIR损伤大鼠模型。观察各时相点(1)血浆肿瘤坏死因子(TNF-α)和内毒素(LPS)水平的变化;(2)血浆和肺组织的磷脂酶A2(PLA2)和弹性蛋白酶(NE)活性的变化;(3)肺组织髓过氧化物酶(MPO)活性的变化;(4)肺组织湿干重比值(W/D)的变化。结果:成功复制了大鼠GIR模型,GIR损伤可引起(1)血浆PLA2活性和LPS水平的较缺血前明显上升(均P<0.01);(2)再灌注后各时点血浆NE活性和TNF-α水平较缺血前明显增高(均P<0.01);(3)再灌注后各时点肺组织的MPO、PLA2和NE活性较缺血前明显增加(P<0.05或P<0.01);(4)再灌注后各时点肺W/D均显著高于缺血前水平(均P<0.01);(5)肺W/D的变化不仅与血浆LPS、TNF-α、NE密切相关,而且与肺组织中MPO、PLA2也密切相关。结论:大鼠GIR后,血浆LPS、TNF-α和NE大量释放及肺组织中PMN活化、扣押和PLA2的激活促发和加重了肺组织损伤。

Objective To investigate the roles of inflammatory mediators and sequestration of neutrophils in lung injury induced by intestinal ischemia-reperfusion （IIR） in rats. Methods A murine model of IIR was established by clamping superior mesenteric artery for one hour. 36 Wister rats were randomized to blank group （30 min before IIR, n = 6） and IIR group ; the latter group was further divided into five subgroups （3, 6, 24, 48, and 72 hours after IIR, n = 6）. At different time points, plasma levels of LPS and TNF-α, activities of phospholipase A2（PLA2） and elastase （NE） in plasma and the lung tissues, myeloperoxidase （MPO） activity and the W/D lung weight ratio in the lung tissues were determined. Results The model of IIR was successfully constructed. As compal：ed with the blank group, plasma levels of LPS and TNF-α and activities of PLA2 and NE were significantly elevated in the five subgroups （P 〈 0.01 for all comparisons）, so were activities of MPO, PLA2, and NE in the lung tissues （P 〈 0.05 or P 〈 0.01） and the W/D lung weight ratio （P 〈 0.01 ）. The change in the W/D weight ratio was not only closely associated with plasma LPS, TNF-α, and NE, but also with MPO and PLA2 in the lung tissues. Conclusion In rats with IIR, a massive release of NE, TNF-α, and LPS in plasma, activation and sequestration of neutrophils in the lung tissue, and PLA2 activation trigger and worsen lung injury.