糖调节蛋白78在大鼠肠源性内毒素血症促进肝硬化形成中的作用

目的:探讨糖调节蛋白78(GRP78)在大鼠肠源性内毒素血症(IETM)促进肝硬化形成过程中的作用。方法:51只雄性Wistar大鼠随机分为肝硬化模型4周组、6周组、8周组及同期正常对照组。采用复合致病因素法诱导大鼠肝硬化,HE染色和VG染色分别观察肝损伤和肝纤维化情况;RT-PCR法和免疫组化法分别检测肝组织GRP78 mRNA及蛋白表达;同时测定血浆中丙氨酸氨基转移酶(ALT)、内毒素、肿瘤坏死因子-α(TNF-α)、同型半胱氨酸(HCY)以及肝组织匀浆中TNF-α、丙二醛(MDA)、Ⅲ型前胶原(PⅢP)水平。结果:(1)随病程进展,各模型组血浆中ALT、内毒素、TNF-α、HCY以及肝组织中GRP78 mRNA、蛋白表达水平、MDA、TNF-α、PⅢP含量和肝组织纤维化指数均逐渐升高并显著高于正常对照组(P0.05)。(2)血浆中升高的内毒素水平分别与GRP78蛋白、血浆MDA和HCY水平以及肝纤维化指数呈显著正相关(P0.01);表达增高的GRP78蛋白分别与血浆MDA和HCY水平以及肝纤维化指数呈显著正相关(P0.01)。结论:GRP78可能在肝硬化形成过程中发挥重要作用;内质网应激很可能是IETM促进肝纤维化乃至肝硬化发生的重要机制。

Role of 78 kD glucose-regulated protein in the development of liver cirrhosis promoted by intestinal endotoxemia in rats

AIM: To explore the role of 78 kD glucose-regulated protein (GRP78) in the development of liver cirrhosis in rats promoted by intestinal endotoxemia (IETM). METHODS: Fifty-one male Wistar rats were randomly divided into liver cirrhosis groups of 4th-week, 6th-week and 8th-week, and normal control group at the corresponding time points. The rat model of hepatic cirrhosis was induced by employing multiple pathogenic factors to the animals. The liver injury and hepatic fibrosis were observed with the staining of HE and VG, respectively. The expression of GRP78 at the mRNA and protein levels was measured by the methods of RT-PCR and immnunohistochemistry, respectively. The concentrations of alanine aminotransferase(ALT), endotoxin, TNF-α and homocystine (HCY) in plasma, and the content of TNF-α, malondialdehyde(MDA) and PⅢP in liver tissues were detected. RESULTS: As liver cirrhosis developed, the levels of ALT, endotoxin, TNF-α and HCY in plasma, the expression of GRP78 at mRNA and protein, the content of TNF-α, MDA and PⅢP in liver tissues, and the index of liver fibrosis were gradually increased and were significantly higher than those in normal control group (P<0.05). Elevated endotoxin in plasma was correlated positively with the protein expression of GRP78, the content of MDA and HCY in plasma and the index of liver fibrosis (P<0.01). Elevated protein expression of GRP78 was correlated positively with the content of MDA and HCY in plasma and the index of liver fibrosis (P<0.01). CONCLUSION: GRP78 plays an important role in the development of liver cirrhosis. Endoplasmic reticulum stress is a possible mechanism in the development of liver cirrhosis promoted by IETM.