脂多糖通过上调SSAO活性抑制泡沫细胞ABCA1表达和促进细胞内脂质蓄积

Lipopolysaccharide Inhibits Foam Cell ABCA1 Expression and Promotes Intracellular Lipid Accumulation by Up-regulating SSAO Activity

目的探讨脂多糖(LPS)是否通过调节氨基脲敏感性胺氧化酶(SSAO)活性改变血管平滑肌细胞源性泡沫细胞三磷酸腺苷结合盒转运体A1(ABCA1)蛋白质的表达和脂质蓄积。方法氧化型低密度脂蛋白(ox-LDL)孵育小鼠主动脉平滑肌原代细胞使其泡沫化,不同浓度LPS和SSAO抑制剂氨基脲(SEM)处理细胞6 h后,高效液相色谱分析细胞SSAO活性、总胆固醇、游离胆固醇和胆固醇酯含量,葡萄糖氧化酶-过氧化物酶法检测培养基葡萄糖含量,荧光分光光度计检测过氧化氢(H2O2)含量,液体闪烁计数器检测细胞内胆固醇流出,Western blot检测ABCA1蛋白质表达的变化。结果 LPS增加泡沫细胞SSAO活性,促进葡萄糖消耗,增加H2O2生成,SEM作用后完全抑制此作用;LPS抑制细胞ABCA1蛋白质的表达,细胞内胆固醇流出减少,细胞总胆固醇、游胆固醇与胆固醇酯增加;SEM作用后部分抑制LPS的这种作用。结论 LPS下调ABCA1蛋白质表达而促进细胞内脂质蓄积与SSAO活性增加相关。

Aim To investigate whether the protein expression of ATP-binding cassette transporter A1（ABCA1）and the accumulation of lipid could be regulated by the activity of semicarbazide-sensitive amine oxidase（SSAO） in vascular smooth muscle cells（VSMC） derived foam cells treated with lipopolysaccharide（LPS）. Methods Vascular smooth muscle cells derived foam cells were exposed to different concentration of LPS along or together with SSAO inhibitor semicarbazide（SEM） for 6 hours. The activity of SSAO and the cellular lipid accumulation were determined by high-performance liquid chromatography analysis. The concentration of glucose in the samples was determined in a glucose oxidase-peroxidase method. Fluorospectrophotometer was used to determine the intracellular or medium H2O2 levels. Cholesterol efflux was determined by FJ-2107 P type liquid scintillator. Western blot was used to determine the protein levels of ABCA1. Results The activity of SSAO,glucose consumption,H2O2 production were increased after treated with LPS and these changes can be reversed by SEM completely. The cellular lipid accumulation was increased,while the cellular cholesterol efflux and the protein expression of ABCA1 were decreased in vascular smooth muscle cells derived foam cells but these changes can be reversed by SEM partly. Conclusion LPS can down-regulate the protein expression of ABCA1 and promote the cellular lipid accumulation by up-regulating the activity of SSAO partly in vascular smooth muscle cells derived foam cells.