THP1 macrophages oxidized cholesterol, generating 7-derivative oxysterols specifically released by HDL

• Published in: Steroids Vol. 99; no. Pt B; pp. 212 - 218
• Main Authors: Chen, Yinan, Arnal-Levron, Maud, Lagarde, Michel, Moulin, Philippe, Luquain-Costaz, Celine, Delton, Isabelle
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2015; Elsevier
• Subjects: Androstenes - pharmacology; Animals; Apolipoprotein A-I - metabolism; Cells, Cultured; Cholesterol; Cholesterol - metabolism; Efflux; Endosomes - drug effects; Endosomes - metabolism; Humans; Intracellular Space - metabolism; Ketocholesterols - metabolism; Life Sciences; Lipoproteins, HDL - metabolism; Lipoproteins, LDL - metabolism; Low density lipoprotein; Macrophages; Macrophages - drug effects; Macrophages - metabolism; Mice; Oxidation-Reduction - drug effects; Oxysterols; RAW 264.7 Cells; HDL; oxy; Efflux; CE; LDL; Oxysterols; ApoA1; LE; Macrophages; FC; Low density lipoprotein; Cholesterol; Apolipoprotein A-I/metabolism; Cholesterol/metabolism; Humans; Ketocholesterols/metabolism; Oxidation-Reduction/drug effects; Cells; Endosomes/drug effects/metabolism; Lipoproteins; HDL/metabolism; Animals; Macrophages/drug effects/metabolism; LDL/metabolism; Intracellular Space/metabolism; RAW 264.7 Cells; Cultured; Mice; Androstenes/pharmacology
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2015.02.020

[Display omitted] •THP1 macrophages produce oxysterols from both intracellular and LDL-associated cholesterol.•Intracellular cholesterol oxidation occurs in late endosomes.•Oxysterols are specifically exported by HDL. Macrophages are well recognized as key pathophysiologic agents in many chronic inflammatory diseases, especially atherosclerosis. During atherogenesis process, low density lipoproteins (LDL) undergo oxidation (oxLDL) and become highly atherogenic as they induce a strong accumulation of cholesterol in subendothelial macrophages leading to the formation of foam cells, the major cellular component of fatty streaks. OxLDL are enriched in oxidation products of cholesterol called oxysterols involved in the regulation of cholesterol homeostasis, by their ability to induce cellular oxidative stress and cytotoxicity. Little is known about intracellular oxysterol production in macrophages. Using both radiochemical and mass analyzes, we showed that THP1 macrophages promote the intracellular oxidation of LDL derived-cholesterol as well as intracellular cholesterol, this later mechanism being enhanced by exposure with native or oxLDL. We demonstrated that in both THP1 and Raw 267.4 cells cholesterol oxidation occurs in the late endosomal compartment. Most oxysterols were produced by non-enzymatic routes (7-ketocholesterol and 7α/β-hydroxycholesterol) but enzymatically formed 7α-, 27-hydroxycholesterol were also quantified. Incubation of THP1 macrophages with nLDL or oxLDL, induced a 2- and 100-fold increase in oxysterol production, respectively. Both oxysterols derived from LDL cholesterol and cellular cholesterol were readily exported to HDL whereas apoA1 was inefficient, showing that HDL plays a major role in the removal of excess oxysterols in THP1 macrophages.