Lysophosphatidylcholine and Carotid Intima-Media Thickness in Young Smokers: A Role for Oxidized LDL-Induced Expression of PBMC Lipoprotein-Associated Phospholipase A2?
Background Although cigarette smoking has been associated with carotid intima-media thickness (CIMT) the mechanisms are yet not completely known. Lysophosphatidylcholine (lysoPC), a main product of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity, appears to be a major determinant of the pro-atherogenic properties of oxidized LDL (oxLDL) and to induce proteoglycan synthesis, a main player in intimal thickening. In this study we assessed whether cigarette smoking-induced oxidative stress may influence plasma Lp-PLA2 and lysoPC and Lp-PLA2 expression in peripheral blood mononuclear cells (PBMC), as well as the relationship between lysoPC and CIMT. Methods/Results 45 healthy smokers and 45 age and sex-matched subjects participated in this study. Smokers, compared to non-smokers, showed increased plasma concentrations of oxLDL, Lp-PLA2 and lysoPC together with up-regulation of Lp-PLA2 (mRNA and protein) expression in PBMC (P<0.001). Plasma Lp-PLA2 positively correlated with both lysoPC (r=0.639, P<0.001) and PBMC mRNA Lp-PLA2 (r=0.484, P<0.001) in all subjects. Moreover CIMT that was higher in smokers (P<0.001), positively correlated with lysoPC (r=0.55, P<0.001). Then in in vitro study we demonstrated that both oxLDL (at concentrations similar to those found in smoker’s serum) and oxidized phospholipids contained in oxLDL, were able to up-regulate mRNA Lp-PLA2 in PBMC. This effect was likely due, at least in part, to the enrichment in oxidized phospholipids found in PBMC after exposure to oxLDL. Our results also showed that in human aortic smooth muscle cells lysoPC, at concentrations similar to those found in smokers, increased the expression of biglycan and versican, two main proteoglycans. Conclusions In smokers a further effect of raised oxidative stress is the up-regulation of Lp-PLA2 expression in PBMC with subsequent increase of plasma Lp-PLA2 and lysoPC. Moreover the correlation between lysoPC and CIMT together with the finding that lysoPC up-regulates proteoglycan synthesis suggests that lysoPC may be a link between smoking and intimal thickening.
Ambrose JA, Barua RS (2004) The pathophysiology of cigarette smoking and cardiovascular disease: an update. J Am Coll Cardiol 43: 1731-1737. doi:10.1016/j.jacc.2003.12.047. PubMed: 15145091.
[3]
Benowitz NL (2003) Cigarette smoking and cardiovascular disease: pathophysiology and implications for treatment. Prog Cardiovasc Dis 46: 91-111. doi:10.1016/S0033-0620(03)00087-2. PubMed: 12920702.
[4]
Csiszar A, Podlutsky A, Wolin MS, Losonczy G, Pacher P et al. (2009) Oxidative stress and accelerated vascular aging: implications for cigarette smoking. Front Biosci 14: 3128-3144. PubMed: 19273262.
[5]
Garbin U, Fratta Pasini A, Stranieri C, Cominacini M, Pasini A, et al. (2009) Cigarette smoking blocks the protective expression of Nrf2/ARE pathway in peripheral mononuclear cells of adult heavy smokers favouring inflammation. PLoS One 9;4(12): e8225.
[6]
Fratta Pasini A, Albiero A, Stranieri C, Cominacini M, Pasini A et al. (2012) Serum oxidative stress-induced repression of Nrf2 and GSH depletion: a mechanism potentially involved in endothelial dysfunction of adult smokers. PLOS ONE 7(1): e30291. doi:10.1371/journal.pone.0030291. PubMed: 22272327.
[7]
Epps KC, Wilensky RL (2011) Lp-PLA2 – a novel risk factor for high-risk coronary and carotid artery disease. J Intern Med 269: 94-106. doi:10.1111/j.1365-2796.2010.02297.x. PubMed: 21054587.
De Keyzer D, Karabina SA, Wei W, Geeraert B, Stengel D et al. (2009) Increased PAFAH and oxidized lipids are associated with inflammation and atherosclerosis in hypercholesterolemic pigs. Arterioscler Thromb Vasc Biol 29: 2041-2046. doi:10.1161/ATVBAHA.109.196592. PubMed: 19797705.
[10]
Wang WY, Li J, Yang D, Xu W, Zha RP, et al. (2010) OxLDL stimulates lipoprotein-associated phospholipase A2 expression in THP-1 monocytes via PI3K and p38 MAPK pathways. Cardiovasc Res 85: 845-852. doi:10.1093/cvr/cvp367. PubMed: 19910444.
[11]
Matsumoto T, Kobayashi T, Kamata K (2007) Role of lysophosphatidylcholine in atherosclerosis. Curr Med Chem 14: 3209-3220.
[12]
O’Leary DH, Polak JF, Kronmal RA, Manolio TA, Wolfson SK et al. (1999) Carotid artery intima and media thickness as a risk factor for myocardial infarction and stroke in older adults. N Engl J Med 340: 14-22. doi:10.1056/NEJM199901073400103. PubMed: 9878640.
[13]
Lorenz MW, Markus HS, Bots ML, Rosvall M, Sitzer M (2007) Prediction of clinical cardiovascular events with carotid intima-media thickness. Circulation 115: 459-467. doi:10.1161/CIRCULATIONAHA.106.628875. PubMed: 17242284.
[14]
Finn AV, Kolodgie FD, Virmani R ( 2010) Correlation between carotid intimal/medial thickness and atherosclerosis: a point of view from pathology. Arterioscler Thromb Vasc Biol 30: 177–181. doi:10.1161/ATVBAHA.108.173609. PubMed: 19679833.
[15]
Falk E, Shah PK, Fuster V (1995) Coronary plaque disruption. Circulation 92: 657–667. doi:10.1161/01.CIR.92.3.657. PubMed: 7634481.
[16]
Howard G, Wagenknecht LE, Burke GL, Diez-Roux A, Evans GW et al. (1998) Cigarette smoking and progression of atherosclerosis: The Atherosclerosis Risk in Communities (ARIC) Study. JAMA 279: 119-124. doi:10.1001/jama.279.2.119. PubMed: 9440661.
[17]
Johnson HM, Piper ME, Jorenby DE, Fiore MC, Baker TB et al. (2010) Risk factors for subclinical carotid atherosclerosis among current smokers. Prev Cardiol 13: 166-171. doi:10.1111/j.1751-7141.2010.00068.x. PubMed: 20860639.
[18]
Wight T (1996) The vascular extracellular matrix. In: V. FusterR. RossEJ Topol. Atherosclerosis and coronary artery disease. Philadelphia: Lippincott Raven. pp. 421-440.
[19]
Little PJ, Ballinger ML, Osman N (2007) Vascular wall proteoglycan synthesis and structure as a target for the prevention of atherosclerosis. Vasc Health Risk Manag 3: 1-8. PubMed: 17583170.
[20]
Nakashima Y, Wight TN, Sueishi K (2008) Early atherosclerosis in humans: role of diffuse intimal thickening and extracellular matrix proteoglycans. Cardiovasc Res 79: 14-23. doi:10.1093/cvr/cvn099. PubMed: 18430750.
[21]
Nakashima Y, Chen YX, Kinukawa N, Sueishi K (2002) Distributions of diffuse intimal thickening in human arteries: preferential expression in atherosclerosis-prone arteries from an early age. Virchows Arch 441: 279-288. doi:10.1007/s00428-002-0605-1. PubMed: 12242525.
[22]
Nakashima Y, Fujii H, Sumiyoshi S, Wight TN, Sueishi K (2007) Early human atherosclerosis. Accumulation of lipid and proteoglycans in intimal thickenings followed by macrophage infiltration. Arterioscler Thromb Vasc Biol 27: 1159-1165. doi:10.1161/ATVBAHA.106.134080. PubMed: 17303781.
[23]
Chang MY, Potter-Perigo S, Tsoi C, Chait A, Wight TN (2000) Oxidized low density lipoproteins regulate synthesis of monkey aortic smooth muscle cell proteoglycans that have enhanced native low density lipoprotein binding properties. J Biol Chem 275: 4766-4773. doi:10.1074/jbc.275.7.4766. PubMed: 10671509.
[24]
Chang MY, Tsoi C, Wight TN, Chait A (2003) Lysophosphatidylcholine regulates synthesis of biglycan and the proteoglycan form of macrophage colony stimulating factor. Arterioscler Thromb Vasc Biol 23: 809-815. doi:10.1161/01.ATV.0000069208.20268.D0. PubMed: 12663372.
[25]
Chang MY, Han CY, Wight TN, Chait A (2006) Antioxidants inhibit the ability of lysophosphatidylcholine to regulate proteoglycan synthesis. Arterioscler Thromb Vasc Biol 26: 494-500. PubMed: 16357313.
[26]
Touboul PJ, Hennerici MG, Meairs S, Adams H, Amarenco P, et al. (2007) An Update on behalf of the Advisory Board of the 3rd and 4th Watching the Risk Symposium 13th and 15th European Stroke Conferences, Mannheim, Germany, 2004, and Brussels, Belgium, 2006. Cerebrovasc Dis 23: 75-80.
[27]
Bianchini E, Bozec E, Gemignani V, Faita F, Laurent S et al. (2010) Assessment of carotid stiffness and intima-media thickness from ultrasound data: comparison between two methods. J Ultrasound Med 29: 1169-1175. PubMed: 20660450.
[28]
Fratta Pasini A, Anselmi M, Garbin U, Franchi E, Stranieri C et al. (2007) Enhanced levels of oxidized low-density lipoprotein prime monocytes to cytokine overproduction via upregulation of CD14 and toll-like receptor 4 in unstable angina. Arterioscler Thromb Vasc Biol 27: 1991-1997. doi:10.1161/ATVBAHA.107.142695. PubMed: 17600225.
[29]
Holvoet P, Mertens A, Verhamme P, Bogaerts K, Beyens G et al. (2001) Circulating oxidized LDL is a useful marker for identifying patients with coronary artery disease. Arterioscler Thromb Vasc Biol 21: 844-848. doi:10.1161/01.ATV.21.5.844. PubMed: 11348884.
[30]
Cominacini L, Fratta Pasini A, Garbin U, Davoli A, Tosetti ML et al. (2000) Oxidized low density lipoprotein (oxLDL) binding to oxLDL receptor-1 in endothelial cells induces the activation of NF-kappaB through an increased production of intracellular reactive oxygen species. J Biol Chem 275: 12633-12638. doi:10.1074/jbc.275.17.12633. PubMed: 10777555.
[31]
Tao Z, Smart FW, Figueroa JE, Glancy DL, Vijayagopal P (1997) Elevated expression of proteoglycans in proliferating vascular smooth muscle cells. Atherosclerosis 135: 171-179. doi:10.1016/S0021-9150(97)00158-5. PubMed: 9430366.
[32]
Gruber F, Oskolkova O, Leitner A, Mildner M, Tschachler E et al. (2007) Photooxidation generates biologically active phospholipids that induce heme oxygenase-1 in skin cells. J Biol Chem 282: 16934-16941. doi:10.1074/jbc.M702523200. PubMed: 17449870.
[33]
Watson AD, Leitinger N, Navab M, Faull KF, H？rkk？ S et al. (1997) Structural identification by mass spectrometry of oxidized phospholipids in minimally oxidized low density lipoprotein that induce monocyte/endothelial interactions and evidence for their presence in vivo. J Biol Chem 272: 13597-13607. doi:10.1074/jbc.272.21.13597. PubMed: 9153208.
Persson M, Nilsson JA, Nelson JJ, Hedblad B, Berglund G (2007) The epidemiology of Lp-PLA(2): distribution and correlation with cardiovascular risk factors in a population-based cohort. Atherosclerosis190: 388-396. doi:10.1016/j.atherosclerosis.2006.02.016. PubMed: 16530769.
[36]
Tselepis AD, Panagiotakos DB, Pitsavos C, Tellis CC, Chrysohoou C et al. (2009) Smoking induces lipoprotein-associated phospholipase A2 in cardiovascular disease free adults: the ATTICA Study. Atherosclerosis 206: 303-308. doi:10.1016/j.atherosclerosis.2009.02.016. PubMed: 19394616.
[37]
Paik JK, Kim JY, Kim OY, Lee Y, Lee JH et al. (2012) Circulating and PBMC Lp-PLA2 associate differently with oxidative stress and subclinical inflammation in nonobese women (menopausal status). PLOS ONE 7: e29675. doi:10.1371/journal.pone.0029675. PubMed: 22359537.
[38]
Bochkov VN, Oskolkova OV, Birukov KG, Levonen AL, Binder CJ et al. (2010) Generation and biological activities of oxidized phospholipids. Antioxid Redox Signal 12: 1009-1059. doi:10.1089/ars.2009.2597. PubMed: 19686040.
[39]
Shi Y, Zhang P, Zhang L, Osman H, Wilensky RL et al. (2007) Role of lipoprotein-associated phospholipase A2 in leukocyte activation and inflammatory responses. Atherosclerosis 191: 54-62. doi:10.1016/j.atherosclerosis.2006.05.001. PubMed: 16765356.
[40]
Kardys I, Oei HH, Van der Meer IM, Hofman A, Witteman JC et al. (2006) Lipoprotein-associated phospholipase A2 and measures of extracoronary atherosclerosis: the Rotterdam Study. Arterioscler Thromb Vasc Biol 26: 631-636. PubMed: 16373603.
[41]
Kiortsis DN, Tsouli S, Lourida ES, Xydis V, Argyropoulou MI et al. (2005) Lack of association between carotid intima-media thickness and PAF acetylhydrolase mass and activity in patients with primary hyperlipidemia. Angiology 56: 451-458. doi:10.1177/000331970505600413. PubMed: 16079929.
