Alcohol Inhibits the Progression as Well as the Initiation of Atherosclerotic Lesions in C57Bl/6 Hyperlipidemic Mice

Moderate dose alcohol protects against serum amyloid protein A1-induced endothelial dysfunction via both notch-dependent and notch-independent pathways

BACKGROUND

Arterial endothelium plays a critical role in maintaining vessel homeostasis and preventing atherosclerotic cardiovascular disease (CVD). Low-to-moderate alcohol (EtOH) consumption is associated with reduced atherosclerosis and stimulates Notch signaling in endothelial cells. The aim of this study was to determine whether EtOH protects the endothelium against serum amyloid A1 (SAA1)-induced activation/injury, and to determine whether this protection is exclusively Notch-dependent.

METHODS AND RESULTS

Human coronary artery endothelial cells (HCAEC) were stimulated or not with "pro-atherogenic" SAA1 (1 μM) in the absence or presence of EtOH (25 mM), the Notch ligand DLL4 (3 μg/ml), or the Notch inhibitor DAPT (20 μM). EtOH stimulated Notch signaling in HCAEC, as evidenced by increased expression of the Notch receptor and hrt target genes. Treatment with EtOH alone or stimulation of Notch signaling by DLL4 increased eNOS activity and enhanced HCAEC barrier function as assessed by trans-endothelial electrical resistance. Moreover, EtOH and DLL4 both inhibited SAA1-induced monolayer leakiness, cell adhesion molecule (ICAM, VCAM) expression, and monocyte adhesion. The effects of EtOH were Notch-dependent, as they were blocked with DAPT and by Notch receptor (N1, N4) knockdown. In contrast, EtOH's inhibition of SAA1-induced inflammatory cytokines (IL-6, IFN-γ) and reactive oxygen species (ROS) was Notch-independent, as these effects were unaffected by DAPT or by N1 and/or N4 knockdown.

CONCLUSIONS

EtOH at moderate levels protects against SAA1-induced endothelial activation via both Notch-dependent and Notch-independent mechanisms. EtOH's maintenance of endothelium in a nonactivated state would be expected to preserve vessel homeostasis and protect against atherosclerosis development.

Early vascular damage from smoking and alcohol in teenage years: the ALSPAC study

Aims

To determine the impact of smoking and alcohol exposure during adolescence on arterial stiffness at 17 years.

Methods and results

Smoking and alcohol use were assessed by questionnaires at 13, 15, and 17 years in 1266 participants (425 males and 841 females) from the ALSPAC study. Smoking status (smokers and non-smoker) and intensity ('high' ≥100, 'moderate' 20-99, and 'low or never' <20 cigarettes in lifetime) were ascertained. Participants were classified by frequency (low or high) and intensity of drinking [light (LI <2), medium (MI 3-9), and heavy (HI >10 drinks on a typical drinking day)]. Carotid to femoral pulse wave velocity (PWV) was assessed at 17 years [mean ± standard deviation and/or mean difference (95% confidence intervals)]. Current smokers had higher PWV compared with non-smokers (P = 0.003). Higher smoking exposure was associated with higher PWV compared with non-smokers [5.81 ± 0.725 vs. 5.71 ± 0.677 m/s, mean adjusted difference 0.211 (0.087-0.334) m/s, P = 0.001]. Participants who stopped smoking had similar PWV to never smokers (P = 0.160). High-intensity drinkers had increased PWV [HI 5.85 ± 0.8 vs. LI 5.67 ± 0.604 m/s, mean adjusted difference 0.266 (0.055-0.476) m/s, P = 0.013]. There was an additive effect of smoking intensity and alcohol intensity, so that 'high' smokers who were also HI drinkers had higher PWV compared with never-smokers and LI drinkers [mean adjusted increase 0.603 (0.229-0.978) m/s, P = 0.002].

Conclusion

Smoking exposure even at low levels and intensity of alcohol use were associated individually and together with increased arterial stiffness. Public health strategies need to prevent adoption of these habits in adolescence to preserve or restore arterial health.

Prevalence and Risk Factors of Carotid Plaque Among Middle-aged and Elderly Adults in Rural Tianjin, China

Carotid plaque (CP) is associated with cardiovascular and cerebrovascular events. However, population-based studies with a large sample are rare in China, particularly those in the low-income population. We aimed to determine the prevalence of CP and the associated risk factors in the rural areas of northern China. Between April 2014 and June 2014, we recruited 3789 residents aged ≥45 years. B-mode ultrasonography was performed to measure the extent of CP. The prevalence of CP was 40.3% overall, 47.1% in men, and 35.4% in women (P < 0.001). The prevalence of CP increased with increasing age (P < 0.001). The participants with CP were more likely to have hypertension, diabetes, high total cholesterol (TC) levels, and high low-density lipoprotein-cholesterol levels and be a current smoker; however, they were less likely to be obese. Multiple logistic regression analysis, adjusted for confounders, indicated that age, male sex, hypertension, diabetes, current smoking, and high LDL-C levels were the independent risk factors for CP. There was a lower risk of CP with alcohol consumption. The findings suggest that managing the conventional risk factors is crucial to reduce the burden of cardiovascular and cerebrovascular diseases in the low-income population in China.

The Effect and Underlying Mechanism of Ethanol on Intracellular H(+) -Equivalent Membrane Transporters in Human Aorta Smooth Muscle Cells

BACKGROUND

The presence of intracellular pH (pHi ) regulators, including Na(+) -H(+) exchanger (NHE), Na(+) -HCO3- co-transporter (NBC), Cl(-) /OH(-) exchanger (CHE), and Cl(-) /HCO3- exchanger (AE), have been confirmed in many mammalian cells. Alcohol consumption is associated with increased risk of cardiovascular disorder. The aims of the study were to identify the possible transmembrane pHi regulators and to explore the effects of ethanol (EtOH) (10 to 300 mM) on the resting pHi and pHi regulators in human aorta smooth muscle cells (HASMCs).

METHODS

HASMCs were obtained from patients undergoing heart transplant. The pHi was measured by microspectrofluorimetry with the pH-sensitive dye, BCECF-AM.

RESULTS

The following results are obtained. (i) In cultured HASMCs, the resting pHi was 7.19 ± 0.04 and 7.13 ± 0.02 for HEPES- and CO2 /HCO3--buffered solution, respectively. (ii) Two different Na(+) -dependent acid-equivalent extruders, including NHE and Na(+) -coupled HCO3- transporter, functionally coexisted. (iii) Two different Cl(-) -dependent acid loaders (CHE and AE) were functionally identified. (iv) EtOH induced a biphasic, concentration-dependent change in resting pHi (+0.25 pH unit at 100 mM but only +0.05 pH unit at 300 mM) in bicarbonate-buffered solution, while caused a concentration-dependent decrease in resting pHi (-0.06 pH unit at 300 mM) in HEPES-buffered solution. (v) The effect of EtOH on NHE activity was also biphasic: increase of 40% at lower concentration of 10 mM, followed by decrease of 30% at higher concentration of 300 mM. (vi) The increase in Na(+) -coupled HCO3- transporter activity by EtOH was concentration dependent. (vii) The effect of EtOH on CHE and AE activities was both biphasic: increase of ~25% at 30 mM, followed by decrease of 10 to 25% at 100 mM, and finally increase of 15 to 20% at 300 mM.

CONCLUSIONS

This study demonstrated that 2 acid extruders and 2 acid loaders coexisted functionally in HASMCs and that EtOH induced a biphasic, concentration-dependent change in resting pHi by altering the activity of the 2 acid extruders, NHE and Na(+) -coupled HCO3- transporter, and the 2 acid loaders, CHE and AE.

Alcohol and cardiovascular disease--modulation of vascular cell function

Alcohol is a commonly used drug worldwide. Epidemiological studies have identified alcohol consumption as a factor that may either positively or negatively influence many diseases including cardiovascular disease, certain cancers and dementia. Often there seems to be a differential effect of various drinking patterns, with frequent moderate consumption of alcohol being salutary and binge drinking or chronic abuse being deleterious to one’s health. A better understanding of the cellular and molecular mechanisms mediating the many effects of alcohol consumption is beginning to emerge, as well as a clearer picture as to whether these effects are due to the direct actions of alcohol itself, or caused in part by its metabolites, e.g., acetaldehyde, or by incidental components present in the alcoholic beverage (e.g., polyphenols in red wine). This review will discuss evidence to date as to how alcohol (ethanol) might affect atherosclerosis that underlies cardiovascular and cerebrovascular disease, and the putative mechanisms involved, focusing on vascular endothelial and smooth muscle cell effects.

Alcohol inhibits smooth muscle cell proliferation via regulation of the Notch signaling pathway

OBJECTIVE

To determine the role of Notch signaling in mediating alcohol's inhibition of smooth muscle cell (SMC) proliferation.

METHODS AND RESULTS

Treatment of human coronary artery SMCs with ethanol (EtOH) decreased Notch 1 mRNA and Notch 1 intracellular domain protein levels, in the absence of any effect on Notch 3. EtOH treatment also decreased C-promoter binding factor-1 (CBF-1)/recombination signal-binding protein (RBP)-jk promoter activity and Notch target gene (hairy related transcription factor [HRT-1] or HRT-2) expression. These effects were concomitant with an inhibitory effect of EtOH on SMC proliferation. Overexpression of constitutively active Notch 1 intracellular domain or human hairy related transcription factor-1 (hHRT-1) prevented the EtOH-induced inhibition of SMC proliferation. In vivo, Notch 1 and HRT-1 mRNA expression was increased after ligation-induced carotid artery remodeling. The vessel remodeling response was inhibited in mice that received "moderate" amounts of alcohol by gavage daily; intimal-medial thickening was markedly reduced, and medial and neointimal SMC proliferating cell nuclear antigen expression was decreased. Moreover, Notch 1 and HRT-1 expression, induced after ligation injury, was inhibited by moderate alcohol consumption.

CONCLUSIONS

EtOH inhibits Notch signaling and, subsequently, SMC proliferation, in vitro and in vivo. The modulation of Notch signaling in SMCs by EtOH may be relevant to the cardiovascular protective effects of moderate alcohol consumption purported by epidemiological studies.

Alcohol consumption is directly associated with carotid intima-media thickness in Finnish young adults: the Cardiovascular Risk in Young Finns Study

OBJECTIVES

There is substantial epidemiological data suggesting a J- or U-shaped association between alcohol consumption and coronary events. However, some studies in experimental animals suggest that alcohol may increase atherosclerosis. Therefore, our aim was to study whether alcohol consumption is associated with carotid intima-media thickness (IMT), marker of subclinical atherosclerosis, in young, healthy adults.

METHODS

Alcohol consumption, carotid IMT and conventional cardiovascular risk factors were investigated in 2074 subjects, aged 24-39 years.

RESULTS

In subjects consuming none, >0 to <2, 2 to <4 or >or=4 units of alcohol per day, the respective carotid IMT values were 0.57+/-0.004, 0.59+/-0.003, 0.59+/-0.006, and 0.60+/-0.012 mm (mean+/-S.E.M., P<0.0001 for increasing IMT trend across alcohol consumption categories). This direct association between alcohol consumption and IMT was independent of age, sex and several cardiovascular risk factors, e.g. blood pressure, LDL-cholesterol, HDL-cholesterol, BMI, smoking, CRP and insulin (P=0.008 in multivariable regression model). The frequencies of drinking wine or strong alcohol beverages (respective P-values 0.03 and 0.01 for increasing IMT trend across beverage consuming frequency) were directly correlated with carotid IMT in models adjusted for age, sex and risk factors.

CONCLUSIONS

We found a direct relationship between alcohol consumption and carotid IMT in young adults. This association was independent of cardiovascular risk factors suggesting that in young healthy adults alcohol consumption may have pro-atherogenic effects.

Acute ethanol exposure disrupts VEGF receptor cell signaling in endothelial cells

Physiological angiogenesis is regulated by various factors, including signaling through vascular endothelial growth factor (VEGF) receptors. We previously reported that a single dose of ethanol (1.4 g/kg), yielding a blood alcohol concentration of 100 mg/dl, significantly impairs angiogenesis in murine wounds, despite adequate levels of VEGF, suggesting direct effects of ethanol on endothelial cell signaling (40). To examine the mechanism by which ethanol influences angiogenesis in wounds, we employed two different in vitro angiogenesis assays to determine whether acute ethanol exposure (100 mg/dl) would have long-lasting effects on VEGF-induced capillary network formation. Ethanol exposure resulted in reduced VEGF-induced cord formation on collagen and reduced capillary network structure on Matrigel in vitro. In addition, ethanol exposure decreased expression of endothelial VEGF receptor-2, as well as VEGF receptor-2 phosphorylation in vitro. Inhibition of ethanol metabolism by 4-methylpyrazole partially abrogated the effect of ethanol on endothelial cell cord formation. However, mice treated with t-butanol, an alcohol not metabolized by alcohol dehydrogenase, exhibited no change in wound vascularity. These results suggest that products of ethanol metabolism are important factors in the development of ethanol-induced changes in endothelial cell responsiveness to VEGF. In vivo, ethanol exposure caused both decreased angiogenesis and increased hypoxia in wounds. Moreover, in vitro experiments demonstrated a direct effect of ethanol on the response to hypoxia in endothelial cells, as ethanol diminished nuclear hypoxia-inducible factor-1alpha protein levels. Together, the data establish that acute ethanol exposure significantly impairs angiogenesis and suggest that this effect is mediated by changes in endothelial cell responsiveness to both VEGF and hypoxia.

Mechanism by which Alcohol and Wine Polyphenols Affect Coronary Heart Disease Risk

The reduction in coronary heart disease (CHD) from moderate alcohol intake may be mediated, in part, by increased fibrinolysis; endothelial cell (EC)-mediated fibrinolysis should decrease acute atherothrombotic consequences (eg, plaque rupture) of myocardial infarction (MI). We have shown that alcohol and individual polyphenols modulate EC fibrinolytic protein (t-PA, u-PA, PAI-1, u-PAR and Annexin-II) expression at the cellular, molecular, and gene levels to sustain increased fibrinolytic activity. Herein we describe the sequence of molecular events by which EC t-PA expression is increased through common activation of p38 MAPK signaling. Up-regulation of t-PA gene transcription, through specific alcohol and polyphenol transcription factor binding sites in the t-PA promoter, results in increased in vitro fibrinolysis and in vivo clot lytic activity (using real-time fluorescence [Fl] imaging of Cy5.5-labeled fibrin clot lysis in a mouse model). Fl-labeled fibrin clots injected into untreated C56Bl/6 wild-type control mice are lysed in approximately 2 hours and clot lytic rates significantly increased in mice treated with either alcohol, catechins, or quercetin (4-6 weeks). Fl-labeled clot lysis in ApoE knock-out mice (atherosclerosis model) showed impaired in vivo clot lysis that was "normalized" to wild-type control levels by treatment with alcohol, catechin, or quercetin for 6 to 8 weeks.

An update on alcohol and atherosclerosis

PURPOSE OF REVIEW

Epidemiological studies consistently link moderate alcohol use with a lower risk of cardiovascular disease, but a number of important issues remain controversial. These include the putative impact of non-alcoholic constituents of some alcoholic beverages, the role of genetic factors, potential mechanisms for this association, and confirmation of the relationship in experimental models.

RECENT FINDINGS

Although high-density lipoprotein cholesterol (HDL-C) is considered the primary mediator of the cardiovascular effects of moderate drinking, recent evidence has shown the alcohol-HDL-C relation is not linear beyond the range of moderate drinking. Moderate alcohol use also has important inverse relations with inflammatory factors. Some, but not all, animal models confirm the anti-atherogenic effects of ethanol and highlight inflammatory factors as one possible mechanism. The non-alcoholic constituents of red wine also have anti-atherogenic and perhaps even life-extending properties in vitro, but their relevance to humans remains uncertain. Genetic variants of the apolipoprotein E and interleukin 6 genes in humans may modify how alcohol influences atherosclerosis, further emphasizing the importance of HDL-C and inflammatory factors as mediators.

SUMMARY

The robust relationship between moderate drinking and lower risk of cardiovascular disease remains an intriguing area of investigation. Clarifying potential gene-environment interactions and translational research into uses for non-alcoholic components will be important areas for future investigation.

Alcohol consumption and coronary atherosclerosis progression—the Stockholm Female Coronary Risk Angiographic Study

OBJECTIVE

To assess the association of alcohol intake with progression of coronary atherosclerosis. Although moderate drinkers have a lower risk of coronary heart disease than abstainers, the relation of alcohol use and coronary atherosclerosis has not been well studied.

METHODS AND RESULTS

In the Stockholm Female Coronary Risk Angiographic Study, we evaluated 103 women, aged 65 years or younger, hospitalized with acute myocardial infarction or unstable angina pectoris who underwent serial quantitative coronary angiography 3-6 months following their index event and repeated an average of 3 years and 3 months (range 2-5 years) later. Individual alcoholic beverage consumption was assessed by a standardized questionnaire. We used mixed model analysis to estimate the effect of alcohol consumption on progression of coronary atherosclerosis, as measured by mean luminal diameter change, controlling for age, smoking, body-mass index, education, physical activity, index cardiac event, menopausal status, diabetes, and history of dyslipidemia. Of the 93 women with complete information on alcohol intake, 14 consumed no alcohol (abstainers), 55 consumed up to 5 g of alcohol per day (light drinkers), and 24 consumed more than 5 g of alcohol per day (moderate drinkers). Coronary atherosclerosis progressed by a multivariate-adjusted average of 0.138 mm (95% confidence interval (CI): 0.027-0.249) among abstainers, 0.137 mm (95% CI: 0.057-0.217) among light drinkers, and -0.054 mm (95% CI: -0.154 to 0.047) among moderate drinkers (P < 0.001). The inverse association persisted in analyses stratified by index event. No beverage type appeared to confer particular benefit.

CONCLUSIONS

Among middle-aged women with coronary heart disease, moderate alcohol consumption (over 5 g/day) was protective of coronary atherosclerosis progression.

Alcohol Reduces GM1 Ganglioside Content in the Serum of Inbred Mouse Strains

BACKGROUND

Endogenous and exogenous gangliosides in the plasma affect physiologic and pathologic processes such as angiogenesis and atherogenesis. However, the genetic and environmental factors that regulate the expression of plasma gangliosides are not well known. As shown in the liver and the brain, profiles of gangliosides in the plasma may be strain-specific and can be altered by intake of alcohol. Therefore, we analyzed serum gangliosides derived from inbred mouse strains with and without alcohol treatment.

METHODS

C57BL/6ByJ (B6By) and BALB/cJ mice (60-70 days old) were injected with 20% alcohol (1-6 g/kg) or saline intraperitoneally, and the ganglioside content of the serum, liver, and cerebellum was measured 4 hr after the injection. Also, the effect of oral alcohol self-administration for 18 days with escalating (3-12%) concentrations of alcohol on the serum GM1 content was studied in B6By mice. The quantification of GM1 was performed with a thin-layer chromatography-staining procedure using a cholera toxin B subunit, and the content of other gangliosides was measured after staining with resorcinol reagent.

RESULTS

We found that basal GM1 (containing N-glycolylneuraminic acid) content in the serum of BALB/cJ mice (4.8 +/- 0.26 ng/microl) was 25 times higher than that of B6By mice (0.19 +/- 0.01 ng/microl); the major ganglioside in both strains was GM2. The ganglioside profile in the liver was similar to that of the serum, and the GM1 content in BALB/cJ was nine times higher than that of B6By. Both injection and oral self-administration of alcohol lowered GM1 levels in the serum.

CONCLUSIONS

Endogenous ganglioside profiles in the serum are under genetic control among inbred mouse strains, and they can be altered by acute and chronic alcohol administration. These genetic and alcohol-induced differences in the plasma gangliosides, which appear to reflect ganglioside metabolism in the liver, may affect alcohol-related behaviors and pathologic processes.

Alcohol Consumption and Carotid Atherosclerosis in Older Adults

OBJECTIVE

The association of alcohol use with atherosclerosis is inconsistent in previous studies.

METHODS AND RESULTS

For the Cardiovascular Health Study, 5888 adults aged 65 years and older underwent a standardized interview and examination. They reported beer, wine, and liquor use individually and underwent B-mode ultrasonography to determine internal and common carotid intima-media thickness (IMT). We compared composite carotid IMT values cross-sectionally using linear regression to adjust for demographic and clinical characteristics. Among 4247 participants free of cardiovascular disease, consumers of 1 to 6 drinks per week had 0.07+/-0.04-mm lower composite IMT and consumers of 14 or more drinks per week had 0.07+/-0.05-mm higher IMT than abstainers (P quadratic trend=0.02). We found similar relationships using internal and common carotid thickness measures and among men and women. The higher IMT associated with heavier alcohol use was particularly strong among 1592 participants with confirmed cardiovascular disease (0.24+/-0.09 mm greater than abstainers). Controlling for HDL cholesterol levels reduced the effect on composite IMT among consumers of 1 to 6 drinks per week by 22%.

CONCLUSIONS

Relative to older adults who abstain from alcohol, consumption of 1 to 6 drinks per week had an inverse association with carotid atherosclerosis whereas consumption of 14 or more drinks had a positive association.

Dietary Cholate Is Required for Antiatherogenic Effects of Ethanol in Mouse Models

BACKGROUND

Human consumption of moderate amounts of ethanol is associated with reduced cardiovascular events. Studies examining the effect of ethanol on atherosclerosis in mouse models have yielded conflicting results that may be due to differences in dietary fat and cholate content. To determine if dietary cholate influences ethanol's effect on atherosclerosis, we fed apolipoprotein E-/- and low-density lipoprotein receptor (LDLR)-/- mice different liquid diets with or without ethanol.

METHODS

Apolipoprotein E-/- mice were fed a low-fat or high saturated fat, cholate-containing diet with or without ethanol for 3 to 10 weeks, and LDLR-/- mice were fed a low-fat, high saturated fat, or high saturated fat diet with cholate with or without ethanol for 7 weeks. At the end of the feeding study, aortic root lesion size was determined and compared with serum cholesterol, triglycerides, and high-density lipoprotein cholesterol. Because dietary cholate increases hepatic nuclear factor (NF)-kappaB and ethanol inhibits NF-kappaB, we also examined the effect of ethanol on aortic NF-kappaB binding activity.

RESULTS

Adding ethanol to a low-fat diet had no effect on lesion size. Similarly, ethanol had no effect on lesion size in LDLR-/- mice consuming a high saturated fat diet. Adding ethanol to a high-fat, cholate-containing diet for either strain resulted in a 25% to 50% reduction in lesion size. Dietary cholate increased and ethanol reduced NF-kappaB binding activity in the aorta.

CONCLUSIONS

These results suggest that ethanol inhibits atherosclerosis in the presence of dietary cholate, which may occur via an anti-inflammatory mechanism.