title: Reduced atherosclerosis in MyD88-null mice links elevated serum cholesterol levels to activation of innate immunity signaling pathways.
abstract: Atherosclerosis, the leading cause of death in developed countries, has been linked to hypercholesterolemia for decades. More recently, atherosclerotic lesion progression has been shown to depend on persistent, chronic inflammation in the artery wall. Although several studies have implicated infectious agents in this process, the role of infection in atherosclerosis remains controversial. Because the involvement of monocytes and macrophages in the pathogenesis of atherosclerosis is well established, we investigated the possibility that macrophage innate immunity signaling pathways normally activated by pathogens might also be activated in response to hyperlipidemia. We examined atherosclerotic lesion development in uninfected, hyperlipidemic mice lacking expression of either lipopolysaccharide (LPS) receptor CD14 or myeloid differentiation protein-88 (MyD88), which transduces cell signaling events downstream of the Toll-like receptors (TLRs), as well as receptors for interleukin-1 (IL-1) and IL-18. Whereas the MyD88-deficient mice evinced a marked reduction in early atherosclerosis, mice deficient in CD14 had no decrease in early lesion development. Inactivation of the MyD88 pathway led to a reduction in atherosclerosis through a decrease in macrophage recruitment to the artery wall that was associated with reduced chemokine levels. These findings link elevated serum lipid levels to a proinflammatory signaling cascade that is also engaged by microbial pathogens.
authors.affiliation: Lipid Metabolism Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Harry
authors.initials: H
authors.lastname: Björkbacka
authors.forename: Vidya V
authors.initials: VV
authors.lastname: Kunjathoor
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Moore
authors.forename: Stephanie
authors.initials: S
authors.lastname: Koehn
authors.forename: Christine M
authors.initials: CM
authors.lastname: Ordija
authors.forename: Melinda A
authors.initials: MA
authors.lastname: Lee
authors.forename: Terry
authors.initials: T
authors.lastname: Means
authors.forename: Kristen
authors.initials: K
authors.lastname: Halmen
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Luster
authors.forename: Douglas T
authors.initials: DT
authors.lastname: Golenbock
authors.forename: Mason W
authors.initials: MW
authors.lastname: Freeman
mesh_terms: D000818:Animals; D001161:Arteriosclerosis / Q000097:blood / Q000235:genetics*; D002784:Cholesterol / Q000097:blood*; D007113:Immunity, Innate; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015398:Signal Transduction
chemical_list: D002784:Cholesterol