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目的:研究感染和炎症时前蛋白转化酶枯草溶菌素9(proprotein convertase subtilisin/kexin type 9,PCSK9)在调节血浆低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)代谢中的作用及其可能的分子机制。方法:用全自动生化仪监测小鼠血浆总胆固醇、高密度脂蛋白胆固醇、甘油三酯、磷脂以及谷氨酸氨基转移酶含量。同时,用快速液相色谱(fast proteinliquid chromatography,FPLC)分析混合的小鼠血浆。血浆淀粉样蛋白A(serum amyloid A,SAA)浓度用酶联免疫吸附法测定。用定量PCR法检测肝脏组织的PCSK9、LDL受体等脂代谢相关基因mRNA丰度,并用Western blot分析肝组织中LDL受体表达变化。结果:研究发现低剂量脂多糖(liposacaridica,LPS)注射24 h后血浆谷氨酸氨基转移酶无明显变化,小鼠血浆LDL-C增高43.02%,高密度脂蛋白胆固醇增高30.09%、甘油三酯增高27.21%,磷脂增高25.50%。LPS注射组动物的血浆SAA明显增多至(1 271.05±94.13)ng/ml,增多的SAA主要与高密度脂蛋白和低密度脂蛋白结合。LPS处理诱导肝脏PCSK9基因表达上调,抑制肝脏LDL受体的蛋白表达。结论:研究表明LPS引起肝细胞中PCSK9上调,LDL受体蛋白表达受抑制,同时小鼠血浆LDL-C迅速增多,提示PCSK9抑制LDL受体通路可能通过影响血浆脂蛋白代谢在炎症导致的宿主反应中起重要作用。
OBJECTIVE: To investigate the role of proprotein convertase subtilisin / kexin type 9 (9) in the regulation of plasma LDL-C metabolism during infection and inflammation Possible molecular mechanisms. Methods: The contents of total cholesterol, high density lipoprotein cholesterol, triglyceride, phospholipid and glutamate aminotransferase in plasma of mice were detected by automatic biochemical analyzer. Simultaneously, pooled mouse plasma was analyzed by fast protein liquid chromatography (FPLC). Serum amyloid A (SAA) concentrations were measured by enzyme-linked immunosorbent assay. Quantitative PCR method was used to detect mRNA abundance of lipid metabolism related genes such as PCSK9 and LDL receptors in liver tissues. The expression of LDL receptor in liver tissue was analyzed by Western blot. Results: The results showed that there was no significant change of plasma glutamate aminotransferase in 24 h after injection of low dose lipopolysaccharide (LPS). LDL-C increased 43.02%, high density lipoprotein cholesterol increased 30.09%, triglyceride Increased by 27.21%, phospholipid increased by 25.50%. The SAA in the LPS injection group increased significantly to (1 271.05 ± 94.13) ng / ml, and the increased SAA was mainly associated with high density lipoprotein and low density lipoprotein. LPS treatment upregulated the expression of PCSK9 gene in liver and inhibited the expression of hepatic LDL receptor. Conclusion: LPS induced upregulation of PCSK9 in hepatocytes and inhibition of LDL receptor protein expression in mice, and rapid increase of plasma LDL-C in mice, suggesting that inhibition of LDL receptor pathway by PCSK9 may affect the host reaction caused by inflammation through the influence of plasma lipoprotein metabolism Play an important role.