CAJ | 학술논문

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。
목적：탐토재생리급염증응격조건하，인단핵세포계（T HP-1）거서세포화혈관평활기세포（VSMCs）、저밀도지단백수체（LDLr）적부반궤조공적세포특이성차별급기가능적궤제。방법지다당（LPS）가입T HP-1거서세포화VSMCs배양기중유도염증응격，매학법검측세포내담고순수평，반전록취합매련반응（RT-PCR）법검측LDLr、SCAP、고순조공원건결합단백2（SREBP2）mRNA수평。결과생리조건하，LDL부하증가세포내담고순수평，진이감소 THP-1거서세포화 VSMCs LDLr mRNA 수평。VSMCs IC50위11．25μg/mL ，저우THP-1거서세포적18．125μg/mL。0～400 ng/mL LPS 정제량의뢰성상조량충세포 LDLr mRNA 수평，단VSMCs LDLr곡선비THP-1거서세포LDLr곡선평탄，200 ng/mL LPS처리하，THP-1거서세포LDLr mRNA상조배수원고우VSMCs（0．33화0．04）。LDLr조단제간소납감소량충세포내유LPS유도적담고순침적。생리조건하，LDL부하감소SREBP2화SCAP mRNA수평，이LPS증가SREBP2화SCAP mRNA수평。결론염증응격재량충세포중균우란세포내담고순수평개도적LDLr부반궤조공，THP-1거서세포LDLr상조정도경대，저가능시염증응격하T HP-1거서세포경역포말화적일개원인。
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 .