title: Macrophage deficiency of Akt2 reduces atherosclerosis in Ldlr null mice.
abstract: Macrophages play crucial roles in the formation of atherosclerotic lesions. Akt, a serine/threonine protein kinase B, is vital for cell proliferation, migration, and survival. Macrophages express three Akt isoforms, Akt1, Akt2, and Akt3, but the roles of Akt1 and Akt2 in atherosclerosis in vivo remain unclear. To dissect the impact of macrophage Akt1 and Akt2 on early atherosclerosis, we generated mice with hematopoietic deficiency of Akt1 or Akt2. After 8 weeks on Western diet, Ldlr(-/-) mice reconstituted with Akt1(-/-) fetal liver cells (Akt1(-/-)→Ldlr(-/-)) had similar atherosclerotic lesion areas compared with control mice transplanted with WT cells (WT→Ldlr(-/-)). In contrast, Akt2(-/-)→Ldlr(-/-) mice had dramatically reduced atherosclerotic lesions compared with WT→Ldlr(-/-) mice of both genders. Similarly, in the setting of advanced atherosclerotic lesions, Akt2(-/-)→Ldlr(-/-) mice had smaller aortic lesions compared with WT→Ldlr(-/-) and Akt1(-/-)→Ldlr(-/-) mice. Importantly, Akt2(-/-)→Ldlr(-/-) mice had reduced numbers of proinflammatory blood monocytes expressing Ly-6C(hi) and chemokine C-C motif receptor 2. Peritoneal macrophages isolated from Akt2(-/-) mice were skewed toward an M2 phenotype and showed decreased expression of proinflammatory genes and reduced cell migration. Our data demonstrate that loss of Akt2 suppresses the ability of macrophages to undergo M1 polarization reducing both early and advanced atherosclerosis.
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Vladimir R
authors.initials: VR
authors.lastname: Babaev
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Katie E
authors.initials: KE
authors.lastname: Hebron
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Carrie B
authors.initials: CB
authors.lastname: Wiese
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Toth
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Lei
authors.initials: L
authors.lastname: Ding
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Youmin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: James M
authors.initials: JM
authors.lastname: May
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232 Department of Pathology, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Sergio
authors.initials: S
authors.lastname: Fazio
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232 Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Kasey C
authors.initials: KC
authors.lastname: Vickers
authors.affiliation: Atherosclerosis Research Unit, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232 Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: MacRae F
authors.initials: MF
authors.lastname: Linton
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000235:genetics; D050197:Atherosclerosis / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002465:Cell Movement; D005260:Female; D005786:Gene Expression Regulation; D055786:Gene Knockout Techniques; D006410:Hematopoiesis; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000378:metabolism; D010641:Phenotype; D051057:Proto-Oncogene Proteins c-akt / Q000172:deficiency* / Q000235:genetics*; D054390:Receptors, CCR2 / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000172:deficiency* / Q000235:genetics
chemical_list: D000950:Antigens, Ly; C515335:Ccr2 protein, mouse; C494192:Ly-6C antigen, mouse; D054390:Receptors, CCR2; D011973:Receptors, LDL; D051057:Proto-Oncogene Proteins c-akt
keywords: apoptosis; cell signaling; foam cells; macrophages/monocytes