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.
BACKGROUND/AIMS: The accumulation of freecholesterol in atherosclerotic lesions has been well documented in both animals and humans. In studying the relevance of freecholesterol buildup in atherosclerosis, contradictory results have been generated, indicating that freecholesterol produces both pro- and anti-atherosclerosis effects in macrophages. This inconsistency might stem from the examination of only select concentrations of freecholesterol. In the present study, we sought to investigate the implication of excess freecholesterol 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 freecholesterol from (in µg/ml) 0 to 20, but gradually decreased at higher concentrations from 20 to 60. Lower freecholesterol 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 freecholesterol resulted in pro-inflammatory M1 activation. Moreover, with the application of higher freecholesterol concentrations, macrophage apoptosis and secretion of the inflammatory cytokine IL-1β increased significantly. CONCLUSION: These results for the first time demonstrate that freecholesterol could render concentration-dependent diversification effects on macrophage viability, polarization, apoptosis and inflammatory cytokine secretions, thereby reconciling the pros and cons of freecholesterol buildup in macrophages to the pathophysiology of atherosclerosis.
Authors: Jonathan E Feig; Sajesh Parathath; James X Rong; Stephanie L Mick; Yuliya Vengrenyuk; Lisa Grauer; Stephen G Young; Edward A Fisher Journal: Circulation Date: 2011-02-21 Impact factor: 29.690
Authors: Machteld M Tiemessen; Ann L Jagger; Hayley G Evans; Martijn J C van Herwijnen; Susan John; Leonie S Taams Journal: Proc Natl Acad Sci U S A Date: 2007-11-27 Impact factor: 11.205
Authors: Ioannis Kokkinopoulos; Mei Mei Wong; Claire M F Potter; Yao Xie; Baoqi Yu; Derek T Warren; Witold N Nowak; Alexandra Le Bras; Zhichao Ni; Chao Zhou; Xiongzhong Ruan; Eirini Karamariti; Yanhua Hu; Li Zhang; Qingbo Xu Journal: Stem Cell Reports Date: 2017-07-27 Impact factor: 7.765
Authors: Xiaoyang Xu; Aolin Zhang; Matthew S Halquist; Xinxu Yuan; Scott C Henderson; William L Dewey; Pin-Lan Li; Ningjun Li; Fan Zhang Journal: J Cell Mol Med Date: 2016-09-15 Impact factor: 5.310