摘要
目的：探讨在生理及炎症应激条件下，人单核细胞系（T HP-1）巨噬细胞和血管平滑肌细胞（VSMCs）、低密度脂蛋白受体（LDLr）的负反馈调控的细胞特异性差别及其可能的机制。方法脂多糖（LPS）加入T HP-1巨噬细胞和VSMCs培养基中诱导炎症应激，酶学法检测细胞内胆固醇水平，反转录聚合酶链反应（RT-PCR）法检测LDLr、SCAP、固醇调控元件结合蛋白2（SREBP2）mRNA水平。结果生理条件下，LDL负荷增加细胞内胆固醇水平，进而减少 THP-1巨噬细胞和 VSMCs LDLr mRNA 水平。VSMCs IC50为11．25μg/mL ，低于THP-1巨噬细胞的18．125μg/mL。0～400 ng/mL LPS 呈剂量依赖性上调两种细胞 LDLr mRNA 水平，但VSMCs LDLr曲线比THP-1巨噬细胞LDLr曲线平坦，200 ng/mL LPS处理下，THP-1巨噬细胞LDLr mRNA上调倍数远高于VSMCs（0．33和0．04）。LDLr阻断剂肝素钠减少两种细胞内由LPS诱导的胆固醇沉积。生理条件下，LDL负荷减少SREBP2和SCAP mRNA水平，而LPS增加SREBP2和SCAP mRNA水平。结论炎症应激在两种细胞中均扰乱细胞内胆固醇水平介导的LDLr负反馈调控，THP-1巨噬细胞LDLr上调程度更大，这可能是炎症应激下T HP-1巨噬细胞更易泡沫化的一个原因。
Objective To investigate cell-specific regulation of LDLr in THP-1 macrophages and human VSMCs under physiological and inflammatory conditions and its potential mechanisms .Methods Inflammatory stress was induced by adding LPS to human THP-1 macrophages and human VSMCs .Intracellular total cholesterol （TC） , free cholesterol （FC） and cholesterol ester （CE） were examined by an enzymic assay .Total cellular RNA was isola-ted from cells for detecting LDLr ,SREBP-2 and SCAP mRNA levels using real-time PCR .Results LDL loading in-creased intracellular cholesterol level ,thereby reduced LDLr mRNA level in both T HP-1 macrophages and VSMCs under physiological conditions .The IC50 in VSMCs was 11 .25 μg/mL ,which is much lower than 18 .125 μg/mL in THP-1 macrophages .With the increase in concentration of LPS （0-400 ng/mL） ,the LDLr mRNA levels were up-regulated in both cells ,but the curve of LDLr mRNA in VSMCs showed more flat than that of THP-1 macrophages . Under the treatment of 200 ng/mL of LPS ,the upregulation fold （URF） of the LDLr mRNA in THP-1 macrophages was much higher than that of VSMCs （0 .33 VS 0 .04） .LDLr blocking agent heparin decreased lipid droplets induced by LPS significantly in THP-1 macrophages and VSMCs .LDL loading reduced the SREBP2 and SCAP mRNA level under physiological conditions .Exposure to LPS caused over-expression of SREBP2 and SCAP despite a high concen-tration of LDL in the culture medium .Conclusion Inflammatory stress disrupts LDLr negative feedback regulation induced by intracellular cholesterol in both cell types ,to a greater degree in THP-1 macrophages ,which could be one reason why THP-1 macrophages are more prone to become foam cells under inflammatory stress .
出处
《检验医学与临床》
CAS
2014年第16期2193-2195,2198,共4页
Laboratory Medicine and Clinic
基金
国家自然科学基金面上项目(30670869)
四川省卫生厅基金项目(2011-110335)
四川省泸州市科技局基金项目(2011-I-S37(6/7))
泸州医学院基金项目(2010-108)
泸州医学院附属医院基金项目(2011-43)
关键词
巨噬细胞
血管平滑肌细胞
脂多糖
低密度脂蛋白受体
固醇调控元件结合蛋白2
SREBP裂解激活蛋白
泡沫细胞
macrophages
vascular smooth muscle cells
lipopolysaccharide
low-density lipoprotein re-ceptor
sterol regulatory element binding protein2
SREBP cleavage-activating protein
foam cells
