游离胆固醇负载对巨噬细胞活力和极化的浓度依赖性多样化效应
Concentration-Dependent Diversifcation Effects of Free Cholesterol Loading on Macrophage Viability and Polarization.
作者信息
Xu Xiaoyang, Zhang Aolin, Li Ningjun, Li Pin-Lan, Zhang Fan
机构信息
Department of Pharmacology & Toxicology, Medical College of Virginia, Virginia Commonwealth University, VA 23298.
出版信息
Cell Physiol Biochem. 2015;37(2):419-431. doi: 10.1159/000430365. Epub 2015 Aug 28.
BACKGROUND/AIMS: The accumulation of free cholesterol in atherosclerotic lesions has been well documented in both animals and humans. In studying the relevance of free cholesterol buildup in atherosclerosis, contradictory results have been generated, indicating that free cholesterol produces both pro- and anti-atherosclerosis effects in macrophages. This inconsistency might stem from the examination of only select concentrations of free cholesterol. In the present study, we sought to investigate the implication of excess free cholesterol loading in the pathophysiology of atherosclerosis across a broad concentration range from (in µg/ml) 0 to 60.
METHODS
Macrophage viability was determined by measuring formazan formation and flow cytometry viable cell counting. The polarization of M1 and M2 macrophages was differentiated by FACS (Fluorescence-Activated Cell Sorting) assay. The secretion of IL-1β in macrophage culture medium was measured by ELISA kit. Macrophage apoptosis was detected by flow cytometry using a TUNEL kit.
RESULTS
Macrophage viability was increased at the treatment of lower concentrations of free cholesterol from (in µg/ml) 0 to 20, but gradually decreased at higher concentrations from 20 to 60. Lower free cholesterol loading induced anti-inflammatory M2 macrophage polarization. The activation of the PPARx03B3; (Peroxisome Proliferator-Activated Receptor gamma) nuclear factor underscored the stimulation of this M2 phenotype. Nevertheless, higher levels of free cholesterol resulted in pro-inflammatory M1 activation. Moreover, with the application of higher free cholesterol concentrations, macrophage apoptosis and secretion of the inflammatory cytokine IL-1β increased significantly.
CONCLUSION
These results for the first time demonstrate that free cholesterol could render concentration-dependent diversification effects on macrophage viability, polarization, apoptosis and inflammatory cytokine secretions, thereby reconciling the pros and cons of free cholesterol buildup in macrophages to the pathophysiology of atherosclerosis.
背景/目的：在动物和人类中，动脉粥样硬化病变中游离胆固醇的积累已有充分记录。在研究游离胆固醇积累与动脉粥样硬化的相关性时，产生了相互矛盾的结果，表明游离胆固醇在巨噬细胞中既产生促动脉粥样硬化作用，也产生抗动脉粥样硬化作用。这种不一致可能源于仅对特定浓度游离胆固醇的研究。在本研究中，我们试图研究在0至60（微克/毫升）的广泛浓度范围内，过量游离胆固醇负荷对动脉粥样硬化病理生理学的影响。
方法
通过测量甲臜形成和流式细胞术活细胞计数来确定巨噬细胞活力。通过荧光激活细胞分选（FACS）测定法区分M1和M2巨噬细胞的极化。使用酶联免疫吸附测定（ELISA）试剂盒测量巨噬细胞培养基中白细胞介素-1β（IL-1β）的分泌。使用TUNEL试剂盒通过流式细胞术检测巨噬细胞凋亡。
结果
在游离胆固醇浓度从0至20（微克/毫升）的较低浓度处理下，巨噬细胞活力增加，但在20至60的较高浓度下逐渐降低。较低的游离胆固醇负荷诱导抗炎性M2巨噬细胞极化。过氧化物酶体增殖物激活受体γ（PPARγ）核因子的激活突出了对这种M2表型的刺激。然而，较高水平的游离胆固醇导致促炎性M1激活。此外，随着游离胆固醇浓度的升高，巨噬细胞凋亡和炎性细胞因子IL-1β的分泌显著增加。
结论
这些结果首次表明，游离胆固醇可对巨噬细胞活力、极化、凋亡和炎性细胞因子分泌产生浓度依赖性的多样化影响，从而调和了巨噬细胞中游离胆固醇积累在动脉粥样硬化病理生理学中的利弊。
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