Tetrahydrobiopterin Restores Microvascular Dysfunction in Young Adult Binge Drinkers

Reactive Oxygen Species Are Central Mediators of Vascular Dysfunction and Hypertension Induced by Ethanol Consumption

Consumption of high amounts of ethanol is a risk factor for development of cardiovascular diseases such as arterial hypertension. The hypertensive state induced by ethanol is a complex multi-factorial event, and oxidative stress is a pathophysiological hallmark of vascular dysfunction associated with ethanol consumption. Increasing levels of reactive oxygen species (ROS) in the vasculature trigger important processes underlying vascular injury, including accumulation of intracellular Ca2+ ions, reduced bioavailability of nitric oxide (NO), activation of mitogen-activated protein kinases (MAPKs), endothelial dysfunction, and loss of the anticontractile effect of perivascular adipose tissue (PVAT). The enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a central role in vascular ROS generation in response to ethanol. Activation of the renin-angiotensin-aldosterone system (RAAS) is an upstream mechanism which contributes to NADPH oxidase stimulation, overproduction of ROS, and vascular dysfunction. This review discusses the mechanisms of vascular dysfunction induced by ethanol, detailing the contribution of ROS to these processes. Data examining the association between neuroendocrine changes and vascular oxidative stress induced by ethanol are also reviewed and discussed. These issues are of paramount interest to public health as ethanol contributes to blood pressure elevation in the general population, and it is linked to cardiovascular conditions and diseases.

New insights into the mechanism of alcohol-mediated organ damage via its impact on immunity, metabolism, and repair pathways: A summary of the 2021 Alcohol and Immunology Research Interest Group (AIRIG) meeting

On November 19th, 2021, the annual Alcohol and Immunology Research Interest Group (AIRIG) meeting was held at Loyola University Chicago Health Sciences Campus in Maywood, Illinois. The 2021 meeting focused on how alcohol misuse is linked to immune system derangements, leading to tissue and organ damage, and how this research can be translated into improving treatment of alcohol-related disease. This meeting was divided into three plenary sessions: the first session focused on how alcohol misuse affects different parts of the immune system, the second session presented research on mechanisms of organ damage from alcohol misuse, and the final session highlighted research on potential therapeutic targets for treating alcohol-mediated tissue damage. Diverse areas of alcohol research were covered during the meeting, from alcohol's effect on pulmonary systems and neuroinflammation to epigenetic changes, senescence markers, and microvesicle particles. These presentations yielded a thoughtful discussion on how the findings can lead to therapeutic treatments for people suffering from alcohol-related diseases.

Alcohol-Induced Oxidative Stress and the Role of Antioxidants in Alcohol Use Disorder: A Systematic Review

Alcohol use disorder (AUD) is a highly prevalent, comorbid, and disabling disorder. The underlying mechanism of ethanol neurotoxicity and the involvement of oxidative stress is still not fully elucidated. However, ethanol metabolism has been associated with increased oxidative stress through alcohol dehydrogenase, the microsomal ethanol oxidation system, and catalase metabolic pathways. We searched the PubMed and genome-wide association studies (GWAS) catalog databases to review the literature systematically and summarized the findings focusing on AUD and alcohol abstinence in relation to oxidative stress. In addition, we reviewed the ClinicalTrials.gov resource of the US National Library of Medicine to identify all ongoing and completed clinical trials that include therapeutic interventions based on antioxidants. The retrieved clinical and preclinical studies show that oxidative stress impacts AUD through genetics, alcohol metabolism, inflammation, and neurodegeneration.

Folic Acid Homeostasis and Its Pathways Related to Hepatic Oxidation in Adolescent Rats Exposed to Binge Drinking

Chronic ethanol consumption and liver disease are intimately related to folic acid (FA) homeostasis. Despite the fact that FA decreases lipid oxidation, its mechanisms are not yet well elucidated. Lately, adolescents have been practising binge drinking (BD), consisting of the intake of a high amount of alcohol in a short time; this is a particularly pro-oxidant form of consumption. The aim of this study is to examine, for the first time, FA homeostasis in BD adolescent rats and its antioxidant properties in the liver. We used adolescent rats, including control rats and rats exposed to an intermittent intraperitoneal BD model, supplemented with or without FA. Renal FA reabsorption and renal FA deposits were increased in BD rats; hepatic deposits were decreased, and heart and serum levels remained unaffected. This depletion in the liver was accompanied by higher transaminase levels; an imbalance in the antioxidant endogenous enzymatic system; lipid and protein oxidation; a decrease in glutathione (GSH) levels; hyper-homocysteinemia (HHcy); an increase in NADPH oxidase (NOX) 1 and NOX4 enzymes; an increase in caspase 9 and 3; and a decrease in the anti-apoptotic metallopeptidase inhibitor 1. Furthermore, BD exposure increased the expression of uncoupled endothelial nitric oxide synthase (eNOS) by increasing reactive nitrogen species generation and the nitration of tyrosine proteins. When FA was administered, hepatic FA levels returned to normal levels; transaminase and lipid and protein oxidation also decreased. Its antioxidant activity was due, in part, to the modulation of superoxide dismutase activity, GSH synthesis and NOX1, NOX4 and caspase expression. FA reduced HHcy and increased the expression of coupled eNOS by increasing tetrahydrobiopterin expression, avoiding nitrosative stress. In conclusion, FA homeostasis and its antioxidant properties are affected in BD adolescent rats, making it clear that this vitamin plays an important role in the oxidative, nitrosative and apoptotic hepatic damage generated by acute ethanol exposure. For this, FA supplementation becomes a potential BD therapy for adolescents, preventing future acute alcohol-related harms.

Endothelial function is preserved in light to moderate alcohol drinkers but is impaired in heavy drinkers in women: Flow-mediated Dilation Japan (FMD-J) study

Light to moderate alcohol consumption has protective effects on all-cause death and coronary artery disease in women. It is thought that light to moderate alcohol consumption has a beneficial effect on vascular function in women. We measured flow-mediated vasodilation (FMD) in 702 women aged 17-86 years who provided information on alcohol consumption. We divided the subjects into four groups: non-drinkers (0 g/week), light drinkers (>0 to 140 g/week), moderate drinkers (>140 to 280 g/week) and heavy drinkers (>280 g/week). There was no significant difference in FMD among the four groups. Multivariate regression analysis revealed that alcohol consumption in non-drinkers and light drinkers was not an independent predictor of FMD (β = -0.001, P = 0.98). We compared 50 moderate drinkers and 50 non-drinkers matched for age and medical histories and 22 heavy drinkers and 22 non-drinkers in matched pair analysis. There was no significant difference in FMD between moderate drinkers and non-drinkers (8.2±4.3% vs. 8.1±3.5, P = 0.91), while FMD in heavy drinkers was significantly lower than that in non-drinkers (5.9±2.5% vs. 8.9±3.5%, P = 0.002). These findings suggest that heavy alcohol consumption is associated with endothelial dysfunction but that light to moderate alcohol consumption is not associated with endothelial dysfunction in women. Clinical trial registration information This study was approved by principal authorities and ethical issues in Japan (University Hospital Medical Information Network UMIN000012952, 01/12/2009). www.umin.ac.jp/.

The Effect of Low-Carbohydrate Diet on Macrovascular and Microvascular Endothelial Function is Not Affected by the Provision of Caloric Restriction in Women with Obesity: A Randomized Study

Obesity impairs both macro- and microvascular endothelial function due to decreased bioavailability of nitric oxide. Current evidence on the effect of low-carbohydrate (LC) diet on endothelial function is conflicting and confounded by the provision of caloric restriction (CR). We tested the hypothesis that LC without CR diet, but not LC with CR diet, would improve macro- and microvascular endothelial function in women with obesity. Twenty-one healthy women with obesity (age: 33 ± 2 years, body mass index: 33.0 ± 0.6 kg/m²; mean ± SEM) were randomly assigned to receive either a LC diet (~10% carbohydrate calories) with CR (n = 12; 500 calorie/day deficit) or a LC diet without CR (n = 9) and completed the 6-week diet intervention. After the intervention, macrovascular endothelial function, measured as brachial artery flow-mediated dilation did not change (7.3 ± 0.9% to 8.0 ± 1.1%, p = 0.7). On the other hand, following the LC diet intervention, regardless of CR, blocking nitric oxide production decreased microvascular endothelial function, measured by arteriolar flow-induced dilation (p ≤ 0.02 for both diets) and the magnitude was more than baseline (p ≤ 0.04). These data suggest improved NO contributions following the intervention. In conclusion, a 6-week LC diet, regardless of CR, may improve microvascular, but not macrovascular endothelial function, via increasing bioavailability of nitric oxide in women with obesity.