异丙酚抑制甲酰基肽受体1减轻脓毒症诱导的小鼠急性肺损伤

Propofol reduces sepsis induced acute lung injury in a murine model by inhibiting formyl peptide receptor 1

为探讨异丙酚在脓毒症诱导的急性肺损伤(acute lung injury, ALI)小鼠模型中的保护作用并通过体外试验观察其对甲酰基肽受体1(formyl peptide receptor 1,FPR1)激动剂诱导的人中性粒细胞活化的抑制作用,将40只小鼠随机分为4组,每组10只:1组为用50μL 10%二甲基亚砜(dimethyl sulfoxide, DMSO)处理的假手术小鼠;2组为用50μL异丙酚(40 mg/kg)处理的假手术小鼠;3组为用50μL 10%DMSO处理的脓毒症小鼠(该模型通过单次腹腔注射200μL LPS构建);4组为用50μL异丙酚(40 mg/kg)处理的脓毒症小鼠。采用免疫组织化学法检测各组小鼠肺组织中FPR1、淋巴细胞抗原6G(lymphocyte antigen 6 complex locus G, Ly6G)表达;髓过氧化物酶(myeloperoxidase, MPO)测定试剂盒评估肺组织中MPO活性;ELISA检测试剂盒评估支气管肺泡灌洗液(bronchoalveolar lavage fluid, BALF)中主要炎性因子水平。此外,体外条件下于培养的人中性粒细胞中分别添加DMSO或异丙酚,采用分光光度法检测中性粒细胞释放弹性蛋白酶和超氧化物的情况;Western blotting检测促分裂原活化的蛋白激酶(mitogen activated protein kinase, MAPK)信号通路蛋白的表达情况。结果显示,脓毒症显著增加了小鼠肺部组织FPR1和Ly6G蛋白表达水平及MPO活性(均P<0.01),而经腹腔异丙酚注射可有效减少FPR1和Ly6G蛋白表达并显著抑制MPO活性(P<0.01)。与假手术组相比,脓毒症小鼠BALF中TNF-α、IL-1β、IL-6和CXCL1表达水平显著增加(均P<0.01),而异丙酚腹腔注射显著逆转了上述变化(均P<0.05)。体外试验结果显示,异丙酚(5~100μmol/L)剂量依赖性地显著减少了N-甲酰-甲硫氨酰-亮氨酰-苯丙氨酸(N-formyl-methionyl-leucyl-phenylalanine, fMLF)诱导的中性粒细胞弹性蛋白酶和超氧化物释放(均P<0.05)。Western blotting分析显示,异丙酚显著降低了fMLF诱导的人中性粒细胞细胞外信号调节激酶(extracellular signal regulated kinase, ERK)、p38 MAPK和c-Jun氨基末端激酶(c-Jun N-terminal kinase, JNK)的磷酸化水平(均P<0.001)。由此,在脓毒症诱导的小鼠ALI模型中,异丙酚腹腔注射可显著改善其肺部损伤,下调FPR1和Ly6G表达及肺组织中中性粒细胞数。进一步体外试验证实,异丙酚对fMLF诱导的中性粒细胞活化的抑制作用是通过与FPR1结合介导的,可抑制FPR1下游信号转导和炎症级联反应。

To investigate the protective effect of propofol in the murine model of acute lung injury(ALI) induced by sepsis, and to observe the inhibitory effect of propofol on human neutrophils activated by formyl peptide receptor 1(FPR1) agonist in vitro, forty mice were equally and randomly divided into the following 4 groups(n=10, respectively): Group 1, sham mice treated with 50 μL 10% dimethyl sulfoxide(DMSO)(this model was established by single injection of 200 μL LPS) introperitoneal;Group 2, sham mice treated with 50 μL propofol(40 mg/kg);Group 3, septic mice treated with 50 μL 10% DMSO(this model was established by single intraperitoneal injection of 200 μL LPS);Group 4, septic mice treated with 50 μL propofol(40 mg/kg). The expression of FPR1 and lymphocyte antigen 6 complex locus G(Ly6 G) in the lung tissue was analyzed by immunohistochemistry. The activity of myeloperoxidase(MPO) in the lung tissue was evaluated by the MPO assay kit and the level of inflammatory factors in bronchoalveolar lavage fluid(BALF) was evaluated by the ELISA kit. The in vitro cultured human neutrophils were treated with DMSO or propofol. The release of elastase and superoxide from neutrophils was measured by spectrophotometry, and the phosphorylation level of proteins in mitogen activated protein kinase(MAPK) pathway was analyzed by Western blotting. Immunohistochemistry results showed that sepsis significantly increased the expression of FPR1 and Ly6 G protein and MPO activity(all P<0.01), while intraperitoneal propofol injection could effectively reduce the expression of FPR1 and Ly6 G protein and inhibit significantly MPO activity(P<0.01). Compared with sham group, sepsis significantly increased the levels of TNF-α, IL-1β, IL-6, and CXCL1 in BALF(all P<0.01), while propofol treatment significantly reversed these changes(all P<0.05). In vitro results showed that propofol(5~100 μmol/L) significantly decreased the release of elastase and superoxide from neutrophils induced by N-formyl-methionyl-leucyl-phenylalanine(fMLF) in a dose-dependent manner(all P<0.05). Western blotting analysis showed that propofol significantly attenuated the fMLF-induced phosphorylation of extracellular signal regulated kinase(ERK), p38 MAPK, and c-Jun N-terminal kinase(JNK) in human neutrophils(all P<0.001). Thus, in the ALI murine model induced by sepsis, propofol improves lung function, alleviates lung injury, and decreases the expression of FPR1, Ly6 G and lung tissue infiltrating neutrophils. Further in vitro experiments showed that the inhibitory effects of propofol on fMLF induced neutrophil activation are mediated by binding to FPR1, which inhibits receptor-mediated downstream signaling and inflammatory cascades.