Document Detail

Interleukin-6 protects human macrophages from cellular cholesterol accumulation and attenuates the proinflammatory response.
MedLine Citation:
PMID:  21757719     Owner:  NLM     Status:  MEDLINE    
Cholesterol-laden monocyte-derived macrophages are phagocytic cells characteristic of early and advanced atherosclerotic lesions. Interleukin-6 (IL-6) is a macrophage secretory product that is abundantly expressed in atherosclerotic plaques but whose precise role in atherogenesis is unclear. The capacity of macrophages to clear apoptotic cells, through the efferocytosis mechanism, as well as to reduce cellular cholesterol accumulation contributes to prevent plaque progression and instability. By virtue of its capacity to promote cellular cholesterol efflux from phagocyte-macrophages, ABCA1 was reported to reduce atherosclerosis. We demonstrated that lipid loading in human macrophages was accompanied by a strong increase of IL-6 secretion. Interestingly, IL-6 markedly induced ABCA1 expression and enhanced ABCA1-mediated cholesterol efflux from human macrophages to apoAI. Stimulation of ABCA1-mediated cholesterol efflux by IL-6 was, however, abolished by selective inhibition of the Jak-2/Stat3 signaling pathway. In addition, we observed that the expression of molecules described to promote efferocytosis, i.e. c-mer proto-oncogene-tyrosine kinase, thrombospondin-1, and transglutaminase 2, was significantly induced in human macrophages upon treatment with IL-6. Consistent with these findings, IL-6 enhanced the capacity of human macrophages to phagocytose apoptotic cells; moreover, we observed that IL-6 stimulates the ABCA1-mediated efflux of cholesterol derived from the ingestion of free cholesterol-loaded apoptotic macrophages. Finally, the treatment of human macrophages with IL-6 led to the establishment of an anti-inflammatory cytokine profile, characterized by an increased secretion of IL-4 and IL-10 together with a decrease of that of IL-1β. Taken together, our results indicate that IL-6 favors the elimination of excess cholesterol in human macrophages and phagocytes by stimulation of ABCA1-mediated cellular free cholesterol efflux and attenuates the macrophage proinflammatory phenotype. Thus, high amounts of IL-6 secreted by lipid laden human macrophages may constitute a protective response from macrophages to prevent accumulation of cytotoxic-free cholesterol. Such a cellular recycling of free cholesterol may contribute to reduce both foam cell formation and the accumulation of apoptotic bodies as well as intraplaque inflammation in atherosclerotic lesions.
Eric Frisdal; Philippe Lesnik; Maryline Olivier; Paul Robillard; M John Chapman; Thierry Huby; Maryse Guerin; Wilfried Le Goff
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-07-08
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  286     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2011 Sep 
Date Detail:
Created Date:  2011-08-29     Completed Date:  2011-10-25     Revised Date:  2013-06-28    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  30926-36     Citation Subset:  IM    
INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France.
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MeSH Terms
ATP-Binding Cassette Transporters / metabolism
Cell Line
Cholesterol / metabolism*
Cytokines / metabolism
Interleukin-6 / metabolism*
Jurkat Cells
Lipoproteins / chemistry
Macrophages / metabolism*
Monocytes / cytology
RNA Interference
Reg. No./Substance:
0/ATP binding cassette transporter 1; 0/Cytokines; 0/Interleukin-6; 0/Lipoproteins; 57-88-5/Cholesterol

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