Atherogenic Lipids Induce Adhesion of Human Coronary Artery Smooth Muscle Cells to Macrophages by Up-regulating Chemokine CX3CL1 on Smooth Muscle Cells in a TNFα-NFκB-dependent Manner

Abstract

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 α production and NF-κB 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. 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 α production and NF-κB 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. Atherosclerosis involves a complex interplay of inflammatory cells, vascular elements, and lipoproteins coordinated by adhesion molecules, cytokines, and chemokines (1Charo I.F. Taubman M.B. Circ. Res. 2004; 95: 858-866Crossref PubMed Scopus (634) Google Scholar, 2Ross R. N. Engl. J. Med. 1999; 340: 115-126Crossref PubMed Scopus (18955) Google Scholar). Oxidation of low density lipoprotein (LDL) 3The abbreviations used are: LDL, low density lipoprotein; oxLDL, oxidized low density lipoprotein; SMC, smooth muscle cells; CASMC, coronary artery smooth muscle cells; PGPC, 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine; POV-PC, 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine; 9-HODE, 9-hydroxy-10E,12Z-octadecadienoic acid ester; 13-HODE, 13-hydroxy-9Z,11E-octadecadienoic acid ester; TNFα, tumor necrosis factor α; sTNFα R, soluble TNFα receptor; RNAi, RNA interference; sRNAi, stealth RNAi; IFN, interferon; IL, interleukin. 3The abbreviations used are: LDL, low density lipoprotein; oxLDL, oxidized low density lipoprotein; SMC, smooth muscle cells; CASMC, coronary artery smooth muscle cells; PGPC, 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine; POV-PC, 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine; 9-HODE, 9-hydroxy-10E,12Z-octadecadienoic acid ester; 13-HODE, 13-hydroxy-9Z,11E-octadecadienoic acid ester; TNFα, tumor necrosis factor α; sTNFα R, soluble TNFα receptor; RNAi, RNA interference; sRNAi, stealth RNAi; IFN, interferon; IL, interleukin. and its accumulation in the subendothelial space are key initiating events that promote accumulation of leukocytes and other cell types that organize over time to form plaque (3Witztum J.L. Lancet. 1994; 344: 793-795Abstract PubMed Scopus (1251) Google Scholar). Leukocyte recruitment mechanisms are unclear; however, recent genetic data from mouse and man have implicated members of the chemokine family, a large group of leukocyte chemoattractants active at G protein-coupled receptors (4Murphy P.M. Pharmacol. Rev. 2002; 54: 227-229Crossref PubMed Scopus (305) Google Scholar). Of these, the evidence for CX3CL1 (also known as fractalkine) and its receptor CX3CR1 is particularly strong (5Combadiere C. Potteaux S. Gao J.L. Esposito B. Casanova S. Lee E.J. Debre P. Tedgui A. Murphy P.M. Mallat Z. Circulation. 2003; 107: 1009-1016Crossref PubMed Scopus (406) Google Scholar, 6Ghilardi G. Biondi M.L. Turri O. Guagnellini E. Scorza R. Stroke. 2004; 35: 1276-1279Crossref PubMed Scopus (42) Google Scholar, 7Lesnik P. Haskell C.A. Charo I.F. J. Clin. Invest. 2003; 111: 333-340Crossref PubMed Scopus (409) Google Scholar, 8McDermott D.H. Halcox J.P.J. Schenke W.H. Waclawiw M.A. Merrell M.N. Epstein N. Quyyumi A.A. Murphy P.M. Circ. Res. 2001; 89: 401-407Crossref PubMed Scopus (216) Google Scholar, 9McDermott D.H. Fong A.M. Yang Q. Sechler J.M. Cupples L.A. Merrell M.N. Wilson P.W.F. D'Agostino R.B. O'Donnell C.J. Patel D.D. Murphy P.M. J. Clin. Invest. 2003; 111: 1241-1250Crossref PubMed Scopus (240) Google Scholar, 10Moatti D. Faure S. Fumeron F. Amara M.E.W. Seknadji P. McDermott D.H. Debre P. Aumont M.C. Murphy P.M. de Prost D. Combadiere C. Blood. 2001; 97: 1925-1928Crossref PubMed Scopus (303) Google Scholar). CX3CL1 is an atypical multimodular chemokine that exists both in membrane-tethered and shed forms. The immobilized form consists of a chemokine domain anchored to the plasma membrane through an extended mucin-like stalk, a transmembrane helix, and an intracellular domain (11Bazan J.F. Bacon K.B. Hardiman G. Wang W. Soo K. Rossi D. Greaves D.R. Zlotnik A. Schall T.J. Nature. 1997; 385: 640-644Crossref PubMed Scopus (1671) Google Scholar). Transmembrane CX3CL1 is an adhesion molecule that mediates integrin-independent cell capture by binding to CX3CR1 on target cells (12Fong A.M. Robinson L.A. Steeber D.A. Tedder T.F. Yoshie O. Imai T. Patel D.D. J. Exp. Med. 1998; 188: 1413-1419Crossref PubMed Scopus (584) Google Scholar). Following protease-mediated release of the chemokine domain (13Garton K.J. Gough P.J. Blobel C.P. Murphy G. Greaves D.R. Dempsey P.J. Raines E.W. J. Biol. Chem. 2001; 276: 37993-38001Abstract Full Text Full Text PDF PubMed Google Scholar, 14Hundhausen C. Misztela D. Berkhout T.A. Broadway N. Saftig P. Reiss K. Hartmann D. Fahrenholz F. Postina R. Matthews V. Kallen K.J. Rose-John S. Ludwig A. Blood. 2003; 102: 1186-1195Crossref PubMed Scopus (538) Google Scholar), CX3CL1 may also promote classical chemotactic responses of CX3CR1+ monocytes, platelets, NK cells, NK-T cells, T cells, and dendritic cells (15Imai T. Hieshima K. Haskell C. Baba M. Nagira M. Nishimura M. Kakizaki M. Takagi S. Nomiyama H. Schall T.J. Yoshie O. Cell. 1997; 91: 521-530Abstract Full Text Full Text PDF PubMed Scopus (1134) Google Scholar). Two lines of cx3cr1-/- mice established on the atherosclerosis-prone apoE-/- background both have decreased lesion formation in the aorta compared with controls, with fewer macrophages infiltrating plaque in the aortic root (5Combadiere C. Potteaux S. Gao J.L. Esposito B. Casanova S. Lee E.J. Debre P. Tedgui A. Murphy P.M. Mallat Z. Circulation. 2003; 107: 1009-1016Crossref PubMed Scopus (406) Google Scholar, 7Lesnik P. Haskell C.A. Charo I.F. J. Clin. Invest. 2003; 111: 333-340Crossref PubMed Scopus (409) Google Scholar). A dysfunctional human CX3CR1 variant named CX3CR1 M280 has been consistently associated in multiple epidemiologic studies with reduced risk of measured disease end points, including coronary endothelial dysfunction and stenosis (8McDermott D.H. Halcox J.P.J. Schenke W.H. Waclawiw M.A. Merrell M.N. Epstein N. Quyyumi A.A. Murphy P.M. Circ. Res. 2001; 89: 401-407Crossref PubMed Scopus (216) Google Scholar), acute coronary events (10Moatti D. Faure S. Fumeron F. Amara M.E.W. Seknadji P. McDermott D.H. Debre P. Aumont M.C. Murphy P.M. de Prost D. Combadiere C. Blood. 2001; 97: 1925-1928Crossref PubMed Scopus (303) Google Scholar), and progression of carotid atherosclerosis (6Ghilardi G. Biondi M.L. Turri O. Guagnellini E. Scorza R. Stroke. 2004; 35: 1276-1279Crossref PubMed Scopus (42) Google Scholar). Consistent with this, deletion of cx3cl1 on an apoE-/- background resulted in decreased brachiocephalic artery lesions; cx3cl1-/-ldlr-/- mice displayed reduced lesion size in both the aortic root and the brachiocephalic artery (16Teupser D. Pavlides S. Tan M. Gutierrez-Ramos J.C. Kolbeck R. Breslow J.L. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: 17795-17800Crossref PubMed Scopus (168) Google Scholar). Neither CX3CL1 nor CX3CR1 has been found in normal human arteries; however, their expression is up-regulated in the context of coronary artery disease on both foam cells and vascular smooth muscle cells in plaque (17Lucas A.D. Bursill C. Guzik T.J. Sadowski J. Channon K.M. Greaves D.R. Circulation. 2003; 108: 2498-2504Crossref PubMed Scopus (139) Google Scholar, 18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google Scholar). Moreover, CX3CL1 on smooth muscle cells (SMCs) was found to co-localize with macrophage CX3CR1 (18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google Scholar), consistent with close proximity of these cells in human plaque (19Stary H.C. Chandler A.B. Glagov S. Guyton J.R. Insull Jr., W. Rosenfeld M.E. Schaffer S.A. C.J. Circulation. 1994; 89: PubMed Scopus Google Scholar, H.C. Chandler A.B. V. Glagov S. Insull Jr., W. Rosenfeld M.E. C.J. Circulation. PubMed Scopus Google Scholar). both cell types are to atherogenic lipids (3Witztum J.L. Lancet. 1994; 344: 793-795Abstract PubMed Scopus (1251) Google that expression and this we have that oxLDL and its oxidized linoleic acid in human acid and acid J. Hartmann S. PubMed Scopus Google Scholar, C.J. PubMed Scopus Google Scholar, W. G. W. A. Chem. 1998; 91: PubMed Scopus Google Scholar), induce of human to macrophages that strongly to CASMCs in a CX3CR1-dependent J. J.F. Murphy P.M. Circulation. PubMed Scopus Google Scholar). we whether the atherogenic lipids regulate CX3CR1 and CX3CL1 expression and function on CASMCs. and oxLDL were from and 13-HODE, and and were from CX3CR1 mouse and mouse and mouse CX3CL1 was from and used for and studies were from TNFα receptor was from TNFα, and were from including human and were from and NF-κB were from human CASMCs and were from CASMC from and evidence of cardiovascular disease. and cell adhesion were from and were in and as by the CASMCs were to prior to of CASMCs were in a for at with oxLDL oxidized and oxidized linoleic lipids were to cell from of were as previously and in with of were at in a at for stimulated with oxLDL oxidized and oxidized linoleic lipids for human these lipid CX3CR1 and to macrophages J. J.F. Murphy P.M. Circulation. PubMed Scopus Google and were used for were and with at for in with and and as previously J. J.F. Murphy P.M. Circulation. PubMed Scopus Google Scholar). mRNA was and by as previously J. J.F. Murphy P.M. Circulation. PubMed Scopus Google Scholar). CASMC and NF-κB was from stealth the of the NF-κB complex and The sRNAi, to low and and that the used to the as the CASMCs were and for primary with with of These of have with of Following cells were in of CASMC and with LDL, oxLDL, lipids at for were with LDL, oxLDL, 9-HODE, for with and for with at were at at for with CASMCs that were stimulated with LDL, oxLDL, 9-HODE, for cells were by and end was measured a on a were by the from the in blocking CASMCs were with an of prior to with and the adhesion was as were in and was in different and CASMC for were and data are as of The of was by the of by by the were considered to be CX3CL1 and CX3CR1 in CX3CL1 nor CX3CR1 have been observed in coronary (18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google Scholar), we found that both were expressed on the of CASMCs in vitro of CX3CL1 was increased by by of LDL, and PGPC, are found in atherosclerotic plaque A.D. N. M. S. J.L. W. D. W. G. A.M. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar), but this oxLDL and 13-HODE, oxidized linoleic of oxLDL found at in plaque J. Hartmann S. PubMed Scopus Google Scholar, C.J. PubMed Scopus Google Scholar, W. G. W. A. Chem. 1998; 91: PubMed Scopus Google Scholar), increased the of and CX3CR1+ cells A and on and CX3CR1+ cells increased when CASMCs were stimulated with oxLDL oxidized linoleic lipids of both was also observed at the mRNA to CASMCs in a adhesion to CASMCs was low both cell types were stimulated with adhesion increased over when but monocytes, were stimulated with oxLDL 9-HODE, cell adhesion increased to a and when but CASMCs were stimulated with oxLDL 9-HODE, both and CASMCs were stimulated assay, adhesion of the cell types increased by CASMCs CX3CL1 in of CASMCs with prior to the adhesion decreased adhesion of of stimulated CASMCs with this antibody strongly and reduced adhesion by oxLDL 9-HODE, and by of CASMCs with the effect on adhesion the that adhesion of macrophages to CASMCs is and by TNFα Oxidized CX3CL1 on pro-inflammatory TNFα, and are in human atherosclerotic lesions A. Mallat Z. Rev. PubMed Scopus Google Scholar). in vitro stimulation with of of these has previously been to induce CX3CL1 expression in vascular endothelial cells and aortic T. H. K. J. 2004; 11: PubMed Scopus Google Scholar, A. Berkhout T. K. P. G. J. 2002; PubMed Scopus Google Scholar), we whether oxidized lipid stimulation induce production of the in CASMCs. in stimulation of cells with induce TNFα 9-HODE, 13-HODE, of oxLDL strongly up-regulated CASMC production of TNFα, and of expression of CX3CL1 CX3CR1 and of TNFα with A and with and production of CASMC antibody of and but in a the oxidized in of cells the CASMC The effect was and for the CASMC and but for the CX3CR1 for and for effect of on cell was observed for the CX3CR1 and Moreover, of the with oxidized expression of CX3CR1 on these cell types and data suggest that TNFα and are the in to stimulation with atherogenic lipids in promote but on CASMCs. but on CASMCs and NF-κB J. C.A. Clin. Rev. 2002; PubMed Scopus Google Scholar, N. A. K. N. M. S. R. D. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: PubMed Scopus Google Scholar). we whether NF-κB atherogenic CX3CL1 on CASMCs. We also the of a effect of these on its that oxidized lipids NF-κB as previously for and endothelial cells K. W. A. M. C. J. J. 2001; Google indirectly by production of factor to of CASMCs with and of in decreased expression of NF-κB R. G. J. S.A. T. M.E. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar), NF-κB a that as a of NF-κB M. H. T. H. T. H. Med. Chem. 2003; 11: PubMed Scopus Google Scholar, M. H. T. F. H. Med. 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Chem. 2004; Full Text Full Text PDF PubMed Scopus Google with decreased risk of cardiovascular disease in (6Ghilardi G. Biondi M.L. Turri O. Guagnellini E. Scorza R. Stroke. 2004; 35: 1276-1279Crossref PubMed Scopus (42) Google Scholar, 8McDermott D.H. Halcox J.P.J. Schenke W.H. Waclawiw M.A. Merrell M.N. Epstein N. Quyyumi A.A. Murphy P.M. Circ. Res. 2001; 89: 401-407Crossref PubMed Scopus (216) Google Scholar, 10Moatti D. Faure S. Fumeron F. Amara M.E.W. Seknadji P. McDermott D.H. Debre P. Aumont M.C. Murphy P.M. de Prost D. Combadiere C. Blood. 2001; 97: 1925-1928Crossref PubMed Scopus (303) Google Scholar), including the D.H. Fong A.M. Yang Q. Sechler J.M. Cupples L.A. Merrell M.N. Wilson P.W.F. D'Agostino R.B. O'Donnell C.J. Patel D.D. Murphy P.M. J. Clin. Invest. 2003; 111: 1241-1250Crossref PubMed Scopus (240) Google Scholar). the and inflammatory of oxLDL and its derivatives as of CX3CL1 and are both expressed in the context of (4Murphy P.M. Pharmacol. Rev. 2002; 54: 227-229Crossref PubMed Scopus (305) Google Scholar). CX3CL1 may in a membrane-tethered soluble form (11Bazan J.F. Bacon K.B. Hardiman G. Wang W. Soo K. Rossi D. Greaves D.R. Zlotnik A. Schall T.J. Nature. 1997; 385: 640-644Crossref PubMed Scopus (1671) Google Scholar, K.J. Gough P.J. Blobel C.P. Murphy G. Greaves D.R. Dempsey P.J. Raines E.W. J. Biol. Chem. 2001; 276: 37993-38001Abstract Full Text Full Text PDF PubMed Google Scholar, 14Hundhausen C. Misztela D. Berkhout T.A. Broadway N. Saftig P. Reiss K. Hartmann D. Fahrenholz F. Postina R. Matthews V. Kallen K.J. Rose-John S. Ludwig A. Blood. 2003; 102: 1186-1195Crossref PubMed Scopus (538) Google Scholar), the data suggest that leukocyte may also be for and of cells in The of at cell types in atherosclerotic lesions H.C. A Pathol. PubMed Scopus Google Scholar, H.C. Biol. PubMed Scopus Google that both the and the receptor (17Lucas A.D. Bursill C. Guzik T.J. Sadowski J. Channon K.M. Greaves D.R. Circulation. 2003; 108: 2498-2504Crossref PubMed Scopus (139) Google Scholar, 18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google that the be for formation of heterotypic are consistent with previously findings of adhesion of and cells to human aortic A. Berkhout T. K. P. G. J. 2002; PubMed Scopus Google Scholar, V. Faure S. N. S. P. Combadiere C. de 2003; PubMed Scopus Google Scholar). is to that the of the atherosclerotic is the of oxLDL and its derivatives (3Witztum J.L. Lancet. 1994; 344: 793-795Abstract PubMed Scopus (1251) Google Scholar), to macrophages P. H. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar, P. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). human atherosclerotic macrophages are the cell of the that are in with (19Stary H.C. Chandler A.B. Glagov S. Guyton J.R. Insull Jr., W. Rosenfeld M.E. Schaffer S.A. C.J. Circulation. 1994; 89: PubMed Scopus Google Scholar, H.C. Chandler A.B. V. Glagov S. Insull Jr., W. Rosenfeld M.E. C.J. Circulation. PubMed Scopus Google Scholar). Moreover, adhesion studies that CX3CR1+ to CASMCs when both cell types are in the of oxidized when CASMCs were stimulated with atherogenic the adhesion increased and cell adhesion was increased when both cell types were These adhesion of and in plaque both cell types are to an (3Witztum J.L. Lancet. 1994; 344: 793-795Abstract PubMed Scopus (1251) Google and are to the adhesion of macrophages to atherogenic is the that the of this in The atherogenic that promote vascular oxLDL (3Witztum J.L. Lancet. 1994; 344: 793-795Abstract PubMed Scopus (1251) Google Scholar), have been to induce expression of adhesion including and on endothelial cells A. C. G. D. G. K. T. S. Q. G. 1997; PubMed Scopus Google Scholar, A. 2001; Full Text Full Text PDF PubMed Scopus Google CX3CL1 is the adhesion molecule by of human atherosclerotic has CX3CL1 expression on and macrophages but on endothelial cells (17Lucas A.D. Bursill C. Guzik T.J. Sadowski J. Channon K.M. Greaves D.R. Circulation. 2003; 108: 2498-2504Crossref PubMed Scopus (139) Google Scholar, 18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google Scholar), the that adhesion in atherosclerosis may be in a cell manner. this integrin-independent adhesion to endothelial cells was to NF-κB A. Res. 2001; PubMed Scopus Google Scholar). adhesion was in These are in with data the of NF-κB on CX3CL1 expression in aortic B. S. S. F. J. 2003; PubMed Scopus Google Scholar). NF-κB in oxidized CASMCs in decreased adhesion compared with adhesion in cells, be that of NF-κB may of other adhesion including and C.J. E. A. R. Cell. PubMed Scopus Google Scholar, R. M. R. U. M. T. W. A. W. V. 1998; PubMed Scopus Google Scholar, R. N. R. M. O. A. W. V. Biol. 2001; PubMed Scopus Google Scholar, U. A. M. W. N. C. Circ. Res. 2004; PubMed Scopus Google Scholar). has also of CX3CL1 in human endothelial and smooth muscle cells T. H. K. J. 2004; 11: PubMed Scopus Google Scholar, A. Berkhout T. K. P. G. J. 2002; PubMed Scopus Google Scholar, V. Faure S. N. S. P. Combadiere C. de 2003; PubMed Scopus Google Scholar). are consistent with these and to a oxidized lipid autocrine loop in and genetic evidence for NF-κB as a of TNFα and CX3CL1 We also found that CASMCs in expressed CX3CL1 and is consistent with a of and CASMCs in human atherosclerotic lesions (17Lucas A.D. Bursill C. Guzik T.J. Sadowski J. Channon K.M. Greaves D.R. Circulation. 2003; 108: 2498-2504Crossref PubMed Scopus (139) Google Scholar). The of this is that be to adhesion in a manner. the of data we suggest a in atherogenic lipids induce production of and however, TNFα and to mediate CX3CL1 the CX3CR1 of CASMCs. is to that in the of TNFα that up-regulated CX3CL1 were low in A. Berkhout T. K. P. G. J. 2002; PubMed Scopus Google Scholar, V. Faure S. N. S. P. Combadiere C. de 2003; PubMed Scopus Google Scholar). data a mechanism to CX3CL1 and CX3CR1 expression may be in the also suggest an for and of foam cells in plaque involving heterotypic adhesive with smooth muscle Consistent with this, of atherosclerotic lesions has that are in in with macrophages (19Stary H.C. Chandler A.B. Glagov S. Guyton J.R. Insull Jr., W. Rosenfeld M.E. Schaffer S.A. C.J. Circulation. 1994; 89: PubMed Scopus Google Scholar, H.C. Chandler A.B. V. Glagov S. Insull Jr., W. Rosenfeld M.E. C.J. Circulation. PubMed Scopus Google Scholar), and CX3CL1 and CX3CR1 have been to be expressed and to co-localize in plaque (17Lucas A.D. Bursill C. Guzik T.J. Sadowski J. Channon K.M. Greaves D.R. Circulation. 2003; 108: 2498-2504Crossref PubMed Scopus (139) Google Scholar, 18Wong B.W.C. Wong D. McManus B.M. Cardiovasc. Pathol. 2002; 11: 332-338Crossref PubMed Scopus (126) Google Scholar). and mechanisms the genetic established previously the and atherosclerosis. the support of CX3CL1 and as as as TNFα as for the and of atherosclerosis. with