急性肺损伤大鼠多形核白细胞L选择素变化及其在肺内扣押中的作用

Changes of L-selectin expression on polymorphonuclear leukocytes and its role during polymorphonuclear leukocytes sequestration in lungs of rats with acute lung injury

目的 探讨急性肺损伤 (ALI)大鼠循环血多形核白细胞 (PMN)L选择素表达的变化及其于肺内扣押中的作用。方法 通过静脉注射内毒素 (5mg/kg)复制大鼠ALI模型 ,5 6只大鼠随机分为7组 ,每组 8只。分别为 :(1)内毒素 5min组 ;(2 )内毒素 15min组 ;(3)内毒素 30min组 ;(4 )内毒素 6 0min组 ;(5 )fucodin干预 5min组 ;(6 )Fucodin干预 15min组 :静脉注射fucodin 5mg/kg后 ,立即静脉注射内毒素 5mg/kg ;(7)正常对照组 :静脉注射等量生理盐水替代内毒素。用免疫荧光间接法和流式细胞仪检测大鼠ALI过程中PMNL选择素蛋白表达的变化 ;用髓过氧化酶 (MPO)分析法及组织学检查定量ALI过程中PMN于肺内的扣押量。结果 (1)PMNL选择素的表达于静脉注射内毒素后 5min为7 8± 1 6 ,与对照组 (10 5± 2 1)比较差异有显著性 (P <0 0 5 ) ,静脉注射内毒素后 15min(2 9± 0 5 )、30min(3 5± 0 7)和 6 0min(4 9± 0 7)与对照组比较差异更具显著性 (P <0 0 1)。 (2 )大鼠肺组织MPO活力于静脉注射内毒素后 5min [(0 35 9± 0 0 74)U/mg肺组织 ]、15min [(0 490± 0 0 6 9)U/mg肺组织 ]、30min [(0 5 6 5± 0 111)U/mg肺组织 ]、6 0min [(0 710± 0 112 )U/mg肺组织 ]与对照组 [(0 0 6 9± 0 0 11)

Objective To explore the changes of L-selectin protein expression on peripheral blood polymorphonuclear leukocytes (PMN) and their role during PMN sequestration in the lungs of rats with acute lung injury (ALI). Methods The model of ALI in rat was established by intravenous injection of E. Coli endotoxin (ET). The protein expression of L-selectin on peripheral blood PMNs was measured by immunofluorescence and flow cytometry. Myeloperoxidase (MPO) enzyme analysis and histology were employed to estimate the quantity of PMN sequestration in lungs of rats during ALI. Results (1) The protein expression of L-selectin on PMN after injection of ET (7.8±1.6) was all significantly lower than that in control group (10.5±2.1,P<0.05). (2)MPO activity increased significantly after injection of ET in comparison with the control group [0.069±0.011) U/mg lung tissue, P<0.01]. The difference was not significant between the fucodin treated 5 min group [(0.391±0.071) U/mg lung tissue] and ET-treated 5 min group [(0.359±0.074) U/mg lung tissue]. But MPO activity was significantly lower in fucodin-treated 15 min group [(0.396±0.061) U/mg lung tissue]than that in ET-treated group at same time point [(0.490±0.069) U/mg lung tissue, P<0.05]. Conclusions (1) In physiological state, L-selectin are consistently expressed on the surface of PMN membrane. The protein expression of L-selectin on PMNs reduces rapidly after injection of ET and is the lowest at 15 min, then gradually increases.(2)The early stage of PMN sequestration in lungs is not dependent on L-selectin, but L-selectin is still important for maintaining a continual PMN sequestration in lungs of rats with ALI.