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目的:探讨葡萄糖调节蛋白78(GRP78)引发大鼠肝肺综合征(HPS)肺微血管重构的机制。方法:Wistar大鼠被随机分为4周组、6周组和8周组3个时点,采用复合致病因素法制备大鼠肝硬化合并HPS模型,并设标准饮食的正常大鼠作为对照组。免疫组化染色法观察肺组织GRP78、Ⅷ因子相关抗原(FⅧ-RAg)C/EBP同源蛋白(CHOP)/生长阻滞及DNA损伤诱导蛋白153(GADD153)、caspase-12、Bcl-2和核因子(nuclear factor,NF)-κB的表达。RT-PCR和Western blotting法检测肺组织血管内皮生长因子(VEGF)mRNA和蛋白表达水平。结果:模型组动物肺组织中GRP78、FⅧ-RAg及VEGF蛋白的表达随HPS进展逐步增高,CHOP/GADD153及caspase-12的表达随HPS进展逐步降低,Bcl-2和NF-κB随病程进展表达逐渐增加,NF-κB尤以胞核表达增高明显。GRP78与FⅧ-RAg及VEGF蛋白水平呈明显正相关(P<0.01),而与CHOP/GADD153及caspase-12的表达呈明显负相关(P<0.01)。在各时点,模型组动物肺组织GRP78和FⅧ-RAg显著高于正常对照组;VEGF蛋白和mRNA均显著高于正常对照组;而CHOP/GADD153及caspase-12的表达均低于正常对照组(P<0.05)。结论:GRP78可能通过促进血管内皮细胞增殖和抑制其凋亡,促进肺微血管重构,导致HPS的发病。
AIM: To investigate the mechanism of pulmonary microvascular remodeling induced by glucose regulated protein 78 (GRP78) in rat hepatopulmonary syndrome (HPS). Methods: Wistar rats were randomly divided into 4 weeks group, 6 weeks group and 8 weeks group at 3 time points. The compound pathogenic factors were used to prepare the rats with cirrhosis and HPS model. Normal rats with standard diet were used as control group. Immunohistochemical staining was used to observe the expression of GRP78, CHV / CHD and DNA damage-inducible protein 153 (GADD153), caspase-12, Bcl-2 and Nuclear factor (NF) -κB expression. The mRNA and protein expression of vascular endothelial growth factor (VEGF) in lung tissue were detected by RT-PCR and Western blotting. Results: The expressions of GRP78, FⅧ-RAg and VEGF in the model group were gradually increased with the progression of HPS. The expression of CHOP / GADD153 and caspase-12 gradually decreased with the progress of HPS, while the expressions of Bcl-2 and NF- Gradually increased, NF-κB especially increased nuclear expression. GRP78 was positively correlated with FⅧ-RAg and VEGF (P <0.01), but negatively correlated with the expression of CHOP / GADD153 and caspase-12 (P <0.01). At each time point, the expression of GRP78 and FⅧ-RAg in model group was significantly higher than that in normal control group; VEGF protein and mRNA in model group were significantly higher than those in normal control group; while expression of CHOP / GADD153 and caspase-12 were lower than those in normal control group (P <0.05). CONCLUSION: GRP78 may promote pulmonary microvascular remodeling by inducing the proliferation of vascular endothelial cells and inhibiting their apoptosis, resulting in the pathogenesis of HPS.