内毒素致新生大鼠肺组织PECAM-1,t-PA,PAI-1表达的改变及其意义

目的　制备新生大鼠肺损伤模型 ,探讨PECAM 1(血小板内皮细胞粘附因子 )和t PA(组织型纤溶酶原激活因子 ) ,PAI 1(纤溶酶原激活物抑制因子 )mRNA在新生大鼠肺损伤中的作用。方法　腹腔注射LPS致新生大鼠肺损伤 ,观察不同时间点肺组织大体 ,光镜和电镜的病理改变 ,应用免疫组化和RT PCR的方法分别检测肺组织PECAM 1蛋白及mRNA和t PA ,PAI 1mRNA的表达改变。结果　病理改变证实了新生大鼠肺出血的发生 ,注射LPS后 ,PECAM 1蛋白及mRNA表达逐渐下降 ,8h和 16h分别达最低值 (分别为 95 1± 9 76 ,0 86 1± 0 0 16 ) ,与正常对照组 (分别为 12 9 5± 6 15 ,1 192± 0 0 35 )相比 ,差异有显著意义 (P <0 0 1)。LPS作用后 ,t PA ,PAI 1mRNA在肺组织的表达呈逐渐上升趋势 ,t PAmRNA表达高峰为给药后 2h(1 195± 0 0 36 ) ,与对照组 (0 781± 0 0 17)比较 ,差异显著意义 (P <0 0 1)。PAI 1mRNA表达高峰为给药后 2～ 8h(分别为 1 178± 0 0 6 9,1 15 3± 0 0 36 ,1 176±0 0 4 4 ) ,与对照组 (0 6 81± 0 0 19)比较 ,差异显著意义 (P <0 0 1)。结论LPS作用于新生大鼠后 ,肺组织PECAM I蛋白及mRNA表达显著降低 ,保护性机制破坏 ;t PA和PAI 1mRNA表达增加 ,随着大鼠病情加重 ,平衡状态遭到破坏 ,局部

Changes of platelet endothelial cell adhesion molecule-1, tissue type plasminogen activator and plasminogen activator inhibitor-1 expression in the lung tissue of neonatal rats after intraperitoneal injection with lipopolysaccharide

OBJECTIVE: To further explore the pathogenesis of neonatal acute lung injury and neonatal pulmonary hemorrhage by establishing the animal model of neonatal acute lung injury (ALI) and by investigating the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1), tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in ALI. METHODS: Totally 88 neonatal rats which were divided into 8 groups randomly including one normal saline control group and 30 min, 1 h, 2 h, 4 h, 8 h, 16 h and 24 h post injection groups. The changes of lung pathology in newborn rats were observed at different time after LPS was injected intraperitoneally. The changes of PECAM-1 protein, t-PA and PAI-1 mRNA expression were measured by immunohistochemistry and RT-PCR. RESULTS: The expression of PECAM-1 protein and mRNA was decreased and the lowest level was reached at 8 h and 16 h post injection, respectively. The average values were 95.1 +/- 9.76 and 0.861 +/- 0.016, respectively, which were significantly lower than those in the control group (129.5 +/- 6.15, 1.192 +/- 0.035, P < 0.01). The expression of t-PA and PAI-1 mRNA was increased after LPS was injected. The highest level of t-PA mRNA expression was observed at 2 h after injection. The average value was 1.195 +/- 0.036, which was significantly higher than that in the control group (0.781 +/- 0.017, P < 0.01). The highest level of PAI-1 mRNA expression was observed at 2 h, 4 h and 8 h post injection. The average values were 1.178 +/- 0.069, 1.153 +/- 0.036 and 1.176 +/- 0.044, respectively, which was significantly higher than those of the control group (0.681 +/- 0.019, P < 0.01). CONCLUSIONS: The expression of PECAM-1 protein and mRNA was decreased after LPS injection, suggesting the disruption of the tissue protective mechanism; the expression of t-PA and PAI-1 mRNA was increased, indicating the presence of a hypercoagulability state. At the same time, the expression of t-PA mRNA was increased which caused the extra-cellular matrix degradation at the early phase after LPS injection. These three phenomena might be the contributory factors to pulmonary hemorrhage.