小鼠全肝缺血再灌注时肺泡巨噬细胞TLR2的激活与肺损伤的机制

目的：探讨肺泡巨噬细胞Toll样受体2（TLR2）的激活机制及其在肝脏缺血再灌注（HIR）中肺损伤的意义。方法：用野生型小鼠C3h/Heouj和TLR4缺失小鼠C3h/Hej建立HIR动物模型。于再灌注1，6，12h后经支气管肺泡灌洗液获取肺泡巨噬细胞，采用荧光定量PCR方法检测TLR2/4mRNA的表达。同时检测支气管肺泡灌洗液中内毒素及肿瘤坏死因子（TNF）的水平，肺组织湿干重比值，肺组织髓过氧化物酶的浓度，并进行肺组织学评分。结果：C3h/Heouj组HIR缺血再灌后各时点肺泡巨噬细胞TLR2/4mRNA表达升高，TLR2mRNA表达持续升高，TLR4mRNA6h达到最高值。同时C3h/Heouj组HIR后支气管肺泡灌洗液中TNF水平明显升高，肺损伤加重，肺组织湿干重比值持续升高，肺组织髓过氧化物酶持续增加(P<0.05)。C3h/Hej组HIR后TLR2mRNA表达仅轻度升高，且支气管肺泡灌洗液中TNF水平低于C3h/Heouj组(P<0.05)，肺损伤轻于C3h/Heouj组(P<0.05)。结论：HIR可致肺泡巨噬细胞表面TLR4的激活，可上调TLR2的表达，从而可加重HIR时的肺损伤。

The mechanism of TLR2 activation and lung injury during the process of total hepatic ischemia/reperfusion in mice

Abstract:Objective：To explore the mechanism of the activation of Toll-like receptor 2 in alveolar macrophage and its significances in hepatic ischemia/reperfusion(HIR) associated lung injury in mice. Methods：Wild type mice（C3h/Heouj）and TLR4-deficient mice(C3h/HeJ) were used in a model of hepatic ischemia/reperfusion. Alveolar macrophages were collected at the time point of 1h, 6h and 12h after HIR by means of bronchoalveolar lavage (BAL),and the expression of TLR2/4 mRNA was detected with Real-Time PCR. The level of endotoxin and TNF-α in BAL fluid were measured. The concentration of MPO, the ratio of wet/dry weight of lung tissue, and lung histological scores were used to assess the degrees of lung injuries. Results：The expressions of TLR2/4 mRNA in HIR group of C3h/Heouj mice were up-regulated at the all three time points after HIR. The level of TLR2mRNA was increased sustainedly and TLR4 markedly increased at 6h(P<0.01). At the same time TNF-α concentrations in BALF were increased(P<0.01) and lung injuries were aggravated which was indicated by the level of MPO, the ratio of wet/dry weight of lung and lung histological scores. But in TLR4-deficient(C3h/Hej) animals, the activations of TLR2 after HIR were only slight increased. TNF-α levels were significantly decreased compared to wild type mice at three time points after reperfusion(P<0.01), and lung injuries were milder than that in wild typy mice(P<0.05). Conclusions：Toll-like receptor 2 on alveolar macrophage can up-regulate TLR4 expression after HIR, which can aggravated the injury of the lung.