Rubbing salt into wounded endothelium: Sodium potentiates proatherogenic effects of TNF-α under non-uniform shear stress

Summary

Increased consumption of sodium is a risk factor for hypertension and cardiovascular diseases. In vivo studies indicated that high dietary sodium may have a direct negative influence on endothelium. We investigated the effects of high sodium on the endothelial activation during early steps of atherogenesis. Endothelial cells (HUVECs) grown in a model of arterial bifurcations were exposed to shear stress in the presence of normal or high (+ 30 mmol/l) sodium. Adherent THP-1 cells, and the adhesion molecule expression were quantified. Sodium channel blockers, pathways’ inhibitors, and siRNA against tonicity-responsive enhancer binding protein (TonEBP) were used to identify the mechanisms of sodium effects on endothelium. ApoE-deficient mice on low-fat diet received water containing normal or high salt (8% w/v) for four weeks, and the influence of dietary salt on inflammatory cell adhesion in the common carotid artery and carotid bifurcation was measured by intravital microscopy. In vitro, high sodium dramatically increased the endothelial responsiveness to tumour necrosis factor-α under non-uniform shear stress. Sodium-induced increase in monocytic cell adhesion was mediated by reactive oxygen species and the endothelial nitric oxygen synthase, and was sensitive to the knockdown of TonEBP. The results were subsequently confirmed in the ApoE-deficient mice. As compared with normal-salt group, high-salt intake significantly enhanced the adhesion of circulating CD11b+ cells to carotid bifurcations, but not to the straight segment of common carotid artery. In conclusion, elevated sodium has a direct effect on endothelial activation under atherogenic shear stress in vitro and in vivo, and promotes the endothelial-leukocyte interactions even in the absence of increased lipid concentrations.

Keywords

Atherosclerosis - high sodium - endothelial-leukocyte interactions - shear stress - TonEBP

^* Equally contributed as senior authors.

• References

• 1 Go AS, Mozaffarian D, Roger VL. et al. Heart disease and stroke statistics--2013 update: a report from the American Heart Association. Circulation 2013; 127: e6-e245.
• 2 Appel LJ, Frohlich ED, Hall JE. et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke: a call to action from the American Heart Association. Circulation 2011; 123: 1138-1143.
• 3 Verbalis JG. Disorders of body water homeostasis. Best Pract Res Clin Endocrinol Metabol 2003; 17: 471-503.
• 4 Perry IJ, Beevers DG. Salt intake and stroke: a possible direct effect. J Hum Hypertens 1992; 06: 23-25.
• 5 Safar ME, Thuilliez C, Richard V. et al. Pressure-independent contribution of sodium to large artery structure and function in hypertension. Cardiovasc Res 2000; 46: 269-276.
• 6 Simon G. Experimental evidence for blood pressure-independent vascular effects of high sodium diet. Am J Hypertens 2003; 16: 1074-1078.
• 7 Cook NR, Cutler JA, Obarzanek E. et al. Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP). Br Med J 2007; 334: 885-888.
• 8 Strazzullo P, D’Elia L, Kandala NB. et al. Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies. Br Med J 2009; 339: b4567.
• 9 Lim SS, Vos T, Flaxman AD. et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012; 380: 2224-2260.
• 10 Tzemos N, Lim PO, Wong S. et al. Adverse cardiovascular effects of acute salt loading in young normotensive individuals. Hypertension 2008; 51: 1525-1530.
• 11 Jablonski KL, Gates PE, Pierce GL. et al. Low dietary sodium intake is associated with enhanced vascular endothelial function in middle-aged and older adults with elevated systolic blood pressure. Therap Advanc Cardiovasc Dis 2009; 03: 347-356.
• 12 Eufinger SC, Votaw J, Faber T. et al. Habitual dietary sodium intake is inversely associated with coronary flow reserve in middle-aged male twins. Am J Clin Nutr 2012; 95: 572-579.
• 13 Njoroge JN, El Khoudary SR, Fried LF. et al. High urinary sodium is associated with increased carotid intima-media thickness in normotensive overweight and obese adults. Am J Hypertens 2011; 24: 70-76.
• 14 Catanozi S, Rocha JC, Passarelli M. et al. Dietary sodium chloride restriction enhances aortic wall lipid storage and raises plasma lipid concentration in LDL receptor knockout mice. J Lipid Res 2003; 44: 727-732.
• 15 Lu H, Wu C, Howatt DA. et al. Differential effects of dietary sodium intake on blood pressure and atherosclerosis in hypercholesterolemic mice. J Nutr Biochem 2013; 24: 49-53.
• 16 Ivanovski O, Szumilak D, Nguyen-Khoa T. et al. Dietary salt restriction accelerates atherosclerosis in apolipoprotein E-deficient mice. Atherosclerosis 2005; 180: 271-276.
• 17 Ketonen J, Merasto S, Paakkari I. et al. High sodium intake increases vascular superoxide formation and promotes atherosclerosis in apolipoprotein E-deficient mice. Blood Press 2005; 14: 373-382.
• 18 Halterman JA, Kwon HM, Zargham R. et al. Nuclear factor of activated T cells 5 regulates vascular smooth muscle cell phenotypic modulation. Arterioscler Thromb Vasc Biol 2011; 31: 2287-2296.
• 19 Chien S. Molecular and mechanical bases of focal lipid accumulation in arterial wall. Prog Biophys Mol Biol 2003; 83: 131-151.
• 20 Cicha I, Beronov K, Ramirez EL. et al. Shear stress preconditioning modulates endothelial susceptibility to circulating TNF-alpha and monocytic cell recruitment in a simplified model of arterial bifurcations. Atherosclerosis 2009; 207: 93-102.
• 21 Machnik A, Neuhofer W, Jantsch J. et al. Macrophages regulate salt-dependent volume and blood pressure by a vascular endothelial growth factor-C-dependent buffering mechanism. Nat Med 2009; 15: 545-552.
• 22 Drechsler M, Megens RT, van Zandvoort M. et al. Hyperlipidemia-triggered neutrophilia promotes early atherosclerosis. Circulation 2010; 122: 1837-1845.
• 23 Kusche-Vihrog K, Sobczak K, Bangel N. et al. Aldosterone and amiloride alter ENaC abundance in vascular endothelium. Pflugers Arch 2008; 455: 849-857.
• 24 Traub O, Ishida T, Ishida M. et al. Shear stress-mediated extracellular signal-regulated kinase activation is regulated by sodium in endothelial cells. Potential role for a voltage-dependent sodium channel. J Biol Chem 1999; 274: 20144-20150.
• 25 Hwang J, Saha A, Boo YC. et al. Oscillatory shear stress stimulates endothelial production of O2- from p47phox-dependent NAD(P)H oxidases, leading to monocyte adhesion. J Biol Chem 2003; 278: 47291-47298.
• 26 Harrison D, Griendling KK, Landmesser U. et al. Role of oxidative stress in atherosclerosis. Am J Cardiol 2003; 91: 7A-11A.
• 27 Wilcox CS, Pearlman A. Chemistry and antihypertensive effects of tempol and other nitroxides. Pharmacol Rev 2008; 60: 418-469.
• 28 Schmidt TS, McNeill E, Douglas G. et al. Tetrahydrobiopterin supplementation reduces atherosclerosis and vascular inflammation in apolipoprotein E-knock-out mice. Clin Sci 2010; 119: 131-142.
• 29 Valent S, Toth M. Spectrophotometric analysis of the protective effect of ascorbate against spontaneous oxidation of tetrahydrobiopterin in aqueous solution: kinetic characteristics and potentiation by catalase of ascorbate action. Intern J Biochem Cell Biol 2004; 36: 1266-1280.
• 30 Soehnlein O, Drechsler M, Doring Y. et al. Distinct functions of chemokine receptor axes in the atherogenic mobilization and recruitment of classical monocytes. EMBO Mol Med 2013; 05: 471-481.
• 31 Cardilo-Reis L, Gruber S, Schreier SM. et al. Interleukin-13 protects from atherosclerosis and modulates plaque composition by skewing the macrophage phenotype. EMBO Mol Med 2012; 04: 1072-1086.
• 32 Ochi H, Masuda J, Gimbrone MA. Hyperosmotic stimuli inhibit VCAM-1 expression in cultured endothelial cells via effects on interferon regulatory factor-1 expression and activity. Eur J Immunol 2002; 32: 1821-1831.
• 33 Oberleithner H, Peters W, Kusche-Vihrog K. et al. Salt overload damages the glycocalyx sodium barrier of vascular endothelium. Pflugers Arch 2011; 462: 519-528.
• 34 Korte S, Wiesinger A, Straeter AS. et al. Firewall function of the endothelial glycocalyx in the regulation of sodium homeostasis. Pflugers Arch 2012; 463: 269-278.
• 35 Haldenby KA, Chappell DC, Winlove CP. et al. Focal and regional variations in the composition of the glycocalyx of large vessel endothelium. J Vasc Res 1994; 31: 2-9.
• 36 van den Berg BM, Spaan JA, Rolf TM. et al. Atherogenic region and diet diminish glycocalyx dimension and increase intima-to-media ratios at murine carotid artery bifurcation. Am J Physiol Heart Circ Physiol 2006; 290: H915-920.
• 37 Koo A, Dewey Jr CF. Garcia-Cardena G. Hemodynamic shear stress characteristic of atherosclerosis-resistant regions promotes glycocalyx formation in cultured endothelial cells. Am J Physiol Cell Physiol 2013; 304: C137-146.
• 38 Nilius B, Droogmans G. Ion channels and their functional role in vascular endothelium. Physiol Rev 2001; 81: 1415-1459.
• 39 Zhu J, Drenjancevic-Peric I, McEwen S. et al. Role of superoxide and angiotensin II suppression in salt-induced changes in endothelial Ca2+ signaling and NO production in rat aorta. Am J Physiol Heart Circ Physiol 2006; 291: H929-938.
• 40 Cicha I, Goppelt-Struebe M, Muehlich S. et al. Pharmacological inhibition of RhoA signaling prevents connective tissue growth factor induction in endothelial cells exposed to non-uniform shear stress. Atherosclerosis 2008; 196: 136-145.
• 41 Zhou X, Ferraris JD, Cai Q. et al. Increased reactive oxygen species contribute to high NaCl-induced activation of the osmoregulatory transcription factor To-nEBP/OREBP. Am J Physiol Renal Physiol 2005; 289: F377-385.
• 42 Zhou X, Ferraris JD, Burg MB. Mitochondrial reactive oxygen species contribute to high NaCl-induced activation of the transcription factor TonEBP/ OREBP. Am J Physiol Renal Physiol 2006; 290: F1169-1176.
• 43 Ketonen J, Mervaala E. Effects of dietary sodium on reactive oxygen species formation and endothelial dysfunction in low-density lipoprotein receptor-deficient mice on high-fat diet. Heart Vessels 2008; 23: 420-429.
• 44 Mori T, Cowley Jr AW. Renal oxidative stress in medullary thick ascending limbs produced by elevated NaCl and glucose. Hypertension 2004; 43: 341-346.
• 45 Fleming I. Molecular mechanisms underlying the activation of eNOS. Pflugers Arch 2010; 459: 793-806.
• 46 Neuhofer W, Fraek ML, Beck FX. Nitric oxide decreases expression of osmoprotective genes via direct inhibition of TonEBP transcriptional activity. Pflugers Arch 2009; 457: 831-843.
• 47 Halterman JA, Kwon HM, Wamhoff BR. Tonicity-independent regulation of the osmosensitive transcription factor TonEBP (NFAT5). Am J Physiol Cell Physiol 2012; 302: C1-8.
• 48 Gallazzini M, Heussler GE, Kunin M. et al. High NaCl-induced activation of CDK5 increases phosphorylation of the osmoprotective transcription factor To-nEBP/OREBP at threonine 135, which contributes to its rapid nuclear localization. Mol Biol Cell 2011; 22: 703-714.
• 49 Roth I, Leroy V, Kwon HM. et al. Osmoprotective transcription factor NFAT5/TonEBP modulates nuclear factor-kappaB activity. Mol Biol Cell 2010; 21: 3459-3474.
• 50 Johansson ME, Bernberg E, Andersson IJ. et al. High-salt diet combined with elevated angiotensin II accelerates atherosclerosis in apolipoprotein E-deficient mice. J Hypertens 2009; 27: 41-47.
• 51 Tikellis C, Pickering RJ, Tsorotes D. et al. Activation of the Renin-Angiotensin system mediates the effects of dietary salt intake on atherogenesis in the apolipoprotein E knockout mouse. Hypertension 2012; 60: 98-105.
• 52 Dotsch M, Busch J, Batenburg M. et al. Strategies to reduce sodium consumption: a food industry perspective. Crit Rev Food Sci Nutr 2009; 49: 841-851.