黄芪多糖对巨噬细胞脂质代谢的影响及机制

Effect and mechanism of astragalus polysaccharide on lipid metabolism of macrophages

目的分析黄芪多糖对巨噬细胞脂质代谢的影响及其机制。方法用不同浓度黄芪多糖处理巨噬细胞,氧化修饰型低密度脂蛋白(ox-LDL)孵育24h;将ATP结合盒转运子A1(ABCA1)siRNA转染巨噬细胞,qRT-PCR和Western blot检测ABCA1mRNA和蛋白的表达;油红O分析泡沫细胞水平;高效液相色谱检测脂质堆积;[3H]标记检测胆固醇流出。结果与对照组相比,黄芪多糖剂量依赖性抑制ox-LDL诱导的巨噬泡沫细胞的形成,同时胆固醇酯(CE)/总胆固醇(TC)比值明显下降,细胞内胆固醇的流出增加(P<0.05)。此外,研究结果显示,黄芪多糖使ABCA1蛋白表达增高(P<0.05),而抑制其表达后,黄芪多糖抑制的脂质堆积水平出现明显增加,同时伴随有胆固醇流出减少(P<0.05)。结论黄芪多糖可能通过调节ABCA1介导的胆固醇逆转运而影响巨噬细胞脂质代谢进程,提示其在易损斑块诱发的心脑血管疾病治疗中具有潜在应用价值。

Objective To explore the effect of astragalus polysaccharide (APS) on oxidized low-density lipoprotein (ox-LDL)-induced lipid metabolism of macrophages and its underlying mechanism. Methods The small interfering RNA (siRNA) targeting ATP binding cassette transporter A1 (ABCA1) was transfected into RAW 264.7 macrophages. Then the cells were stimulated with various concentrations of APS (20 mg/L,60 mg/L and 150 mg/L ),followed by the incubation with 50 mg/L ox-LDL for 24 h. qRT-PCR and Western blot were used to investigate the expression of ABCA1 mRNA and protein. Oil red O was used to analyze the level of foam cells. Lipid accumulation level was assessed by high performance liquid chromatography.[ 3H]-cholesterol was used to evaluate cholesterol efflux. Results APS dose-dependently inhibited ox-LDL-induced formation of macrophage-derived foam cell compared with those in control group ( P <0.05). HPLC analysis confirmed that APS attenuated lipid accumulation in a dose-dependent manner based on the decrease in ratio of cholesterol ester (CE)/total cholesterol (TC),concomitant with up-regulation of cholesterol efflux ( P <0.05),indicating that APS might inhibit lipid deposition in macrophage by enhancing reverse cholesterol transport. Further more,APS dose-dependently increased ABCA1 mRNA and protein levels ( P <0.05). When silencing ABCA1 expression with its specific siRNA,APS-inhibited lipid accumulation was significantly up-regulated,accompanied with the down-regulation of cholesterol efflux ( P <0.05). Conclusion APS may regulate lipid metabolism of macrophages by ABCA1-mediated progress of reverse cholesterol transport. Therefore,this study provides a potential target for the treatment of cardiovascular diseases triggered by vulnerable plaque.