Atherogenic lipids induce adhesion of human coronary artery smooth muscle cells to macrophages by up-regulating chemokine CX3CL1 on smooth muscle cells in a TNFalpha-NFkappaB-dependent manner.
Recent genetic evidence has implicated the adhesive chemokine CX3CL1 and its leukocyte receptor CX3CR1 in atherosclerosis. We previously proposed a mechanism involving foam cell anchorage to vascular smooth muscle cells because: 1) CX3CL1 and CX3CR1 are expressed by both cell types in mouse and human atherosclerotic lesions; 2) foam cells are reduced in lesions in cx3cr1(-/-)apoE(-/-) mice; and 3) proatherogenic lipids (oxidized low density lipoprotein [oxLDL] and oxidized linoleic acid derivatives) induce adhesion of primary human macrophages to primary human coronary artery smooth muscle cells (CASMCs) in vitro in a macrophage CX3CR1-dependent manner. Here we analyze this concept further by testing whether atherogenic lipids regulate expression and function of CX3CL1 and CX3CR1 on CASMCs. We found that both oxLDL and oxidized linoleic acid derivatives indirectly up-regulated CASMC CX3CL1 at both the protein and mRNA levels through an autocrine feedback loop involving tumor necrosis factor alpha production and NF-kappaB signaling. Oxidized lipids also up-regulated CASMC CX3CR1 but through a different mechanism. Oxidized lipid stimulation also increased adhesion of macrophages to CASMCs when CASMCs were stimulated prior to assay, and a synergistic pro-adhesive effect was observed when both cell types were prestimulated. Selective inhibition with a CX3CL1-specific blocking antibody indicated that adhesion was strongly CASMC CX3CL1-dependent. These findings support the hypothesis that CX3CR1 and CX3CL1 mediate heterotypic anchorage of foam cells to CASMCs in the context of atherosclerosis and suggest that this chemokine/chemokine receptor pair may be considered as a pro-inflammatory target for therapeutic intervention in atherosclerotic cardiovascular disease.
Barlic
Jana
J
Molecular Signaling Section, Laboratory of Molecular Immunology, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA.
Zhang
Yuan
Y
Murphy
Philip M
PM
D001057:Apolipoproteins E / Q000235:genetics; D000073883:CX3C Chemokine Receptor 1; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002450:Cell Communication / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C / Q000235:genetics / Q000378:metabolism*; D003324:Coronary Artery Disease / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005487:Foam Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008041:Linoleic Acids / Q000378:metabolism / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D001057:Apolipoproteins E; D000073883:CX3C Chemokine Receptor 1; C515538:CX3CL1 protein, human; C095235:CX3CR1 protein, human; D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C; C515539:Cx3cl1 protein, mouse; D016207:Cytokines; D008041:Linoleic Acids; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D016328:NF-kappa B; D019707:Receptors, Chemokine; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein