大胞饮途径介导血管平滑肌细胞内脂滴聚集

Macropinocytosis mediates accumulation of lipid droplets in vascular smooth muscle cells in vitro

目的探讨大胞饮途径是否介导血管平滑肌细胞(vascular smooth muscle cells,VSMCs)内脂滴聚集。方法组织块贴壁培养法培养VSMCs;免疫荧光染色鉴定原代VSMCs;天然低密度脂蛋白(nLDL,50、200、800μg/mL)及脂多糖(LPS,200 ng/mL)刺激培养VSMCs,构建泡沫细胞模型;流式细胞术检测VSMCs对大胞饮示踪剂Lucifer Yellow(LY)和Di I标记的nLDL(Di I-nLDL)的摄取;油红O染色鉴定VSMCs内脂滴聚集。结果 (1)LPS刺激可促进VSMCs对nLDL呈浓度依赖性地摄取增加,导致细胞内脂滴的聚集逐渐增多。(2)200 ng/mL LPS刺激VSMCs 6 h,VSMCs对LY的摄取增加75%(P<0.01),对Di I-nLDL的摄取增加76%(P<0.01)。(3)应用胞饮抑制剂LY294002后,VSMCs对Di I-nLDL的摄取减少约29%(P<0.01),VSMCs内脂滴聚集明显减少。结论 LPS刺激诱导VSMCs通过大胞饮途径摄取nLDL,从而增加细胞内脂滴的聚集,促进平滑肌源性泡沫细胞形成。

Objective To investigate whether macropinocytosis mediates the accumulation of lipid droplets in vascular smooth muscle cells （VSMCs）. Methods Primary VSMCs were cultured with tissue explant method and identified by immunofluorescence staining. VSMCsderived foam cells were induced by stimulation of the VSMCs with native low-density lipoprotein （nLDL） at 50, 200, or 800 μg/mL and lipopolysaccharide （LPS） at 200 ng/mL. The changes in the uptake of Lucifer Yellow （LY） and DiI-nLDL by the VSMCs were assessed with flow cytometry. Results LPS promoted lipid droplet accumulation in nLDL-stimulated VSMCs in a concentration-dependent manner. The primary cultured VSMCs showed significantly increased LY uptake by 75% （P〈0.01） and DiI-nLDL uptake by 76% （P〈0.01） in response to stimulation with 200 ng/mL LPS for 6 h. The uptake of DiI-nLDL was significantly lowered by 29% （P〈0.01） and lipid droplet accumulation was significantly decreased in the cells after treatment with LY294002 for inhibiting macropinocytosis. Conclusion LPS induces the uptake of nLDL by VSMCs via the macropinocytosis pathway to promote the formation of VSMCs-derived foam cells.