title: Macrophage-derived apolipoprotein E ameliorates dyslipidemia and atherosclerosis in obese apolipoprotein E-deficient mice.
abstract: Previous studies have demonstrated that macrophage-derived apolipoprotein E (apoE) reduces atherosclerotic lesion formation in lean apoE-deficient ((-/-)) mice. apoE has also been demonstrated to play a role in adipocyte differentiation and lipid accumulation. Because the prevalence of obesity has grown to epidemic proportions, we sought to determine whether macrophage-derived apoE could impact atherosclerotic lesion formation or adipose tissue expansion and inflammation in obese apoE(-/-) mice. To this end, we transplanted obese leptin-deficient (ob/ob) apoE(-/-) mice with bone marrow from either ob/ob;apoE(-/-) or ob/ob;apoE(+/+) donors. There were no differences in body weight, total body adipose tissue, or visceral fat pad mass between recipient groups. The presence of macrophage-apoE had no impact on adipose tissue macrophage content or inflammatory cytokine expression. Recipients of apoE(+/+) marrow demonstrated 3.7-fold lower plasma cholesterol (P < 0.001) and 1.7-fold lower plasma triglyceride levels (P < 0.01) by 12 wk after transplantation even though apoE was present in plasma at concentrations <10% of wild-type levels. The reduced plasma lipids reflected a dramatic decrease in very low density lipoprotein and a mild increase in high-density lipoprotein levels. Atherosclerotic lesion area was >10-fold lower in recipients of ob/ob;apoE(+/+) marrow (P < 0.005). Similar results were seen in leptin receptor-deficient (db/db) apoE(-/-) mice. Finally, when bone marrow transplantation was performed in 4-mo-old ob/ob;apoE(-/-) and db/db;apoE(-/-) mice with preexisting lesions, recipients of apoE(+/+) marrow had a 2.8-fold lower lesion area than controls (P = 0.0002). These results demonstrate that macrophage-derived apoE does not impact adipose tissue expansion or inflammatory status; however, even very low levels of macrophage-derived apoE are capable of reducing plasma lipids and atherosclerotic lesion area in obese mice.
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232-0615, USA.
authors.forename: Robin D
authors.initials: RD
authors.lastname: Atkinson
authors.forename: Kimberly R
authors.initials: KR
authors.lastname: Coenen
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Plummer
authors.forename: Marnie L
authors.initials: ML
authors.lastname: Gruen
authors.forename: Alyssa H
authors.initials: AH
authors.lastname: Hasty
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D001823:Body Composition / Q000502:physiology; D016026:Bone Marrow Transplantation / Q000502:physiology; D050171:Dyslipidemias / Q000235:genetics / Q000378:metabolism*; D020738:Leptin / Q000172:deficiency / Q000235:genetics; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009765:Obesity / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001057:Apolipoproteins E; D020738:Leptin; D008055:Lipids; D008074:Lipoproteins