Alcoholic muscle disease and biomembrane perturbations (review)

The Influence of Stress and Binge-Patterned Alcohol Drinking on Mouse Skeletal Muscle Protein Synthesis and Degradation Pathways

Adverse experiences (e.g., acute stress) and alcohol misuse can both impair skeletal muscle homeostasis, resulting in reduced protein synthesis and greater protein breakdown. Exposure to acute stress is a significant risk factor for engaging in alcohol misuse. However, little is known about how these factors together might further affect skeletal muscle health. To that end, this study investigated the effects of acute stress exposure followed by a period of binge-patterned alcohol drinking on signaling factors along mouse skeletal muscle protein synthesis (MPS) and degradation (MPD) pathways. Young adult male C57BL/6J mice participated in the Drinking in the Dark paradigm, where they received 2-4 h of access to 20% ethanol (alcohol group) or water (control group) for four days to establish baseline drinking levels. Three days later, half of the mice in each group were either exposed to a single episode of uncontrollable tail shocks (acute stress) or remained undisturbed in their home cages (no stress). Three days after stress exposure, mice received 4 h of access to 20% ethanol (alcohol) to model binge-patterned alcohol drinking or water for ten consecutive days. Immediately following the final episode of alcohol access, mouse gastrocnemius muscle was extracted to measure changes in relative protein levels along the Akt-mTOR MPS, as well as the ubiquitin-proteasome pathway (UPP) and autophagy MPD pathways via Western blotting. A single exposure to acute stress impaired Akt singling and reduced rates of MPS, independent of alcohol access. This observation was concurrent with a potent increase in heat shock protein seventy expression in the muscle of stressed mice. Alcohol drinking did not exacerbate stress-induced alterations in the MPS and MPD signaling pathways. Instead, changes in the MPS and MPD signaling factors due to alcohol access were primarily observed in non-stressed mice. Taken together, these data suggest that exposure to a stressor of sufficient intensity may cause prolonged disruptions to signaling factors that impact skeletal muscle health and function beyond what could be further induced by periods of alcohol misuse.

Episodic Binge-like Ethanol Reduces Skeletal Muscle Strength Associated with Atrophy, Fibrosis, and Inflammation in Young Rats

Binge Drinking (BD) corresponds to episodes of ingestion of large amounts of ethanol in a short time, typically ≤2 h. BD occurs across all populations, but young and sports-related people are especially vulnerable. However, the short- and long-term effects of episodic BD on skeletal muscle function have been poorly explored. Young rats were randomized into two groups: control and episodic Binge-Like ethanol protocol (BEP) (ethanol 3 g/kg IP, 4 episodes of 2-days ON-2-days OFF paradigm). Muscle function was evaluated two weeks after the last BEP episode. We found that rats exposed to BEP presented decreased muscle strength and increased fatigability, compared with control animals. Furthermore, we observed that skeletal muscle from rats exposed to BEP presented muscle atrophy, evidenced by reduced fiber size and increased expression of atrophic genes. We also observed that BEP induced fibrotic and inflammation markers, accompanied by mislocalization of nNOSµ and high levels of protein nitration. Our findings suggest that episodic binge-like ethanol exposure alters contractile capacity and increases fatigue by mechanisms involving atrophy, fibrosis, and inflammation, which remain for at least two weeks after ethanol clearance. These pathological features are common to several neuromuscular diseases and might affect muscle performance and health in the long term.

The effects of voluntary binge-patterned ethanol ingestion and daily wheel running on signaling of muscle protein synthesis and degradation in female mice

Excessive ethanol ingestion can reduce skeletal muscle protein synthesis (MPS) through the disruption of signaling along the Akt-mTOR pathway and increase muscle protein degradation (MPD) through the Ubiquitin Proteasome Pathway (UPP) and autophagy. Identification of interventions that curb the disrupting effects of alcohol misuse on MPS and MPD are of central importance for the prevention of chronic health complications that arise from muscle loss. Physical activity is one potential strategy to combat the deleterious effects of alcohol on skeletal muscle. Therefore, the purpose of this study was to investigate the interaction between daily wheel running and binge-patterned ethanol consumption, through episodes of voluntary binge-patterned ethanol drinking, on signaling factors along the Akt-mTOR, Ubiquitin-Proteasome, and autophagy pathways. Adult female C57BL/6J mice received daily access to cages with or without running wheels for 2.5 h/day for five weeks. During the final five days of the study, mice received 2-4 h of daily access to sipper tubes containing water (n = 14 sedentary; n = 15 running) or 20% ethanol (n = 14 sedentary; n = 16 running) 30 min after running wheel access, using the "Drinking in the Dark" (DID) model of binge-patterned ethanol consumption. Immediately after the final episode of DID, gastrocnemius muscle was extracted. Western blotting was performed to measure proteins along Akt-mTOR, Ubiquitin-Proteasome, and autophagy pathways, and PCR was used to assess mRNA expression of atrogenes. Ethanol access increased expression of MAFbx by 82% (p = 0.048), but did not robustly influence Akt-mTOR or UPP signaling. Daily wheel access did not prevent alcohol-induced MAFbx expression; however, ethanol access decreased the phosphorylation of p70S6K by 45% in running mice (p = 0.020). These results suggest that physical activity may be insufficient to prevent alcohol-induced changes to signaling factors along pathways involved in muscle loss. Instead, binge-patterned ethanol ingestion may impair the benefits of physical activity on factors involved in MPS.

Mac-2-binding protein glycosylation isomer is useful to predict muscle cramps in patients with chronic liver disease

Muscle cramps are frequently overlooked and worsen the quality of life in patients with chronic liver disease (CLD). Therefore, a valuable biomarker for predicting muscle cramps is required in the clinical setting. This study aimed to investigate whether the serum Mac-2-binding protein glycosylation isomer (M2BPGi) levels, a reliable liver fibrosis marker, could predict muscle cramps in patients with CLD. This retrospective study included 80 patients with CLD. Muscle cramps were assessed using a questionnaire regarding their presence, frequency, pain severity, and duration. The associated predictors were analyzed using logistic regression analysis. The diagnostic accuracy and optimal cutoff values were evaluated using receiver operating characteristic curves. Of the 80 patients, 55% had muscle cramps and showed significantly higher serum M2BPGi levels than those without them (4.54 cutoff index [COI] vs 2.20; P = .001). Multivariate analysis revealed that M2BPGi (odds ratio [ORs], 1.19; 95% confidence interval, 1.003-1.42; P = .046) was independently associated with the presence of muscle cramps. The optimal COI value for predicting muscle cramps was 3.95, and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 61.4%, 80.6%, 79.4%, 63.0%, and 70.0%, respectively. Patients with a COI value ≥3.95 had a 2-fold higher incidence of muscle cramps than patients with a COI value <3.95 (79% vs 37%; P < .001). M2BPGi levels were also associated with the duration of muscle cramps. Serum M2BPGi appears useful as a biomarker for predicting muscle cramps in patients with CLD.

Neuromuscular mechanisms of weakness in a mouse model of chronic alcoholic myopathy

BACKGROUND

Weakness is a common clinical symptom reported in individuals with chronic alcohol use disorder. However, it remains unclear whether low strength in these individuals is directly related to excessive ethanol intake, other deleterious factors (lifestyle, environment, genetics, etc.), or a combination of both. Therefore, we examined whether (and how) ethanol reduces the muscle's force-producing capacity using a controlled in vivo preclinical mouse model of excessive ethanol intake.

METHODS

To establish whether chronic ethanol consumption causes weakness, C57BL/6 female mice consumed 20% ethanol for 40 weeks (following a 2-week ethanol ramping period), and various measures of muscular force were quantified. Functional measures included all-limb grip strength and in vivo contractility of the left ankle dorsiflexors and plantarflexors. Once confirmed that mice consuming ethanol were weaker than age-matched controls, we sought to determine the potential neuromuscular mechanisms of muscle dysfunction by assessing neuromuscular excitation, muscle quantity, and muscle quality.

RESULTS

Mice consuming chronic ethanol were 13 to 16% weaker (p ≤ 0.016) than controls (i.e., mice consuming 100% water) with the negative impact of ethanol on voluntary grip strength (ƞ²  = 0.603) being slightly larger than that of electrically stimulated muscle contractility (ƞ²  = 0.482). Relative to controls, lean mass and muscle wet masses were 9 to 16% lower in ethanol-consuming mice (p ≤ 0.048, ƞ²  ≥ 0.268). No significant changes were observed between groups for indices of neuromuscular excitation at the level of the motor unit, neuromuscular junction, or plasmalemma (p ≥ 0.259, ƞ²  ≤ 0.097), nor was muscle quality altered after 40 weeks of 20% ethanol consumption (p ≥ 0.695, ƞ²  ≤ 0.012).

CONCLUSIONS

Together, these findings establish that chronic ethanol consumption in mice induces a substantial weakness in vivo that we interpret to be primarily due to muscle atrophy (i.e., reduced muscle quantity) and possibly, to a lesser degree, loss of central neural drive.

Role of cell-free network communication in alcohol-associated disorders and liver metastasis

The aberrant use of alcohol is a major factor in cancer progression and metastasis. Contributing mechanisms include the systemic effects of alcohol and the exchange of bioactive molecules between cancerous and non-cancerous cells along the brain-gut-liver axis. Such interplay leads to changes in molecular, cellular, and biological functions resulting in cancer progression. Recent investigations have examined the role of extracellular vesicles (EVs) in cancer mechanisms in addition to their contribution as diagnostic biomarkers. Also, EVs are emerging as novel cell-free mediators in pathophysiological scenarios including alcohol-mediated gut microbiome dysbiosis and the release of nanosized EVs into the circulatory system. Interestingly, EVs in cancer patients are enriched with oncogenes, miRNA, lipids, and glycoproteins whose delivery into the hepatic microenvironment may be enhanced by the detrimental effects of alcohol. Proof-of-concept studies indicate that alcohol-associated liver disease is impacted by the effects of exosomes, including altered immune responses, reprogramming of stromal cells, and remodeling of the extracellular matrix. Moreover, the culmination of alcohol-related changes in the liver likely contributes to enhanced hepatic metastases and poor outcomes for cancer patients. This review summarizes the numerous aspects of exosome communications between organs with emphasis on the relationship of EVs in alcohol-associated diseases and cancer metastasis. The potential impact of EV cargo and release along a multi-organ axis is highly relevant to the promotion of tumorigenic mechanisms and metastatic disease. It is hypothesized that EVs target recipient tissues to initiate the formation of prometastatic niches and cancer progression. The study of alcohol-associated mechanisms in metastatic cancers is expected to reveal a better understanding of factors involved in the growth of secondary malignancies as well as novel approaches for therapeutic interventions.

Telmisartan alleviates alcohol-induced liver injury by activation of PPAR-γ/ Nrf-2 crosstalk in mice

Excessive consumption of alcohol may induce severe liver damage, in part via oxidative stress and inflammatory responses, which implicates these processes as potential therapeutic approaches. Prior literature has shown that Telmisartan (TEL) may provide protective effects, presumably mediated by its anti-oxidant and anti-inflammatory activities. The purpose of this study was to determine TEL's hepatoprotective effects and to identify its possible curative mechanisms in alcoholic liver disease. A mouse chronic alcohol plus binge feedings model was used in the current study for induction of alcoholic liver disease (ALD). Our results showed that TEL (10 mg/kg/day) has the ability to reduce serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). TEL also increased the activity of superoxide dismutase (SOD) and glutathione (GSH) with concomitant reduction of nitric oxide (NO) malonaldehyde (MDA) in the liver homogenate. Moreover, TEL downregulated nuclear factor kappa B (NF-κB) expression and decreased liver content of interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). These anti-inflammatory and anti-oxidant activities were associated with a significant increase in the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), peroxisome proliferator-activated receptors -γ (PPAR-γ), and heme oxygenase-1 (Hmox-1). In conclusion, TEL's hepatoprotective effects against ALD may be attributable to its anti-inflammatory and anti-oxidant activities which may be in part via the modulation of PPAR-γ/ Nrf-2/ NF-κB crosstalk.

Protective effect of Terminalia arjuna against alcohol induced oxidative damage of rat erythrocyte membranes

Background

Alcohol is a widely abused drug with many health implications, mainly caused by the oxidative and nitrosative stress on different body parts. Ayurvedic herbalism authenticates the multiple therapeutic applications of Terminalia arjuna bark due to its rich phytochemical repertoire.

Objective

To observe the extent of oxidative damage caused to erythrocytes by alcohol and assess the protective ability of T. arjuna bark powder aqueous extract (AETA) against the damage.

Materials and methods

Wister albino rats were categorized into four groups of eight rats per group; first group (control) was fed with glucose, second group was given alcohol at a dose of 20% v/v; 5g alcohol/kg b. wt/day, third group was co-administered with AETA (0.5 g/kg b. wt/day) and alcohol and the fourth group was kept on bark extract alone. Blood samples were collected and evaluated for different biochemical parameters after the completion of the treatment period.

Results

Alcohol significantly increased the erythrocyte membrane protein carbonyl and malondialdehyde (MDA) contents, along with a concomitant decrease in the membrane antioxidant status, when compared to the control group. Chromatographic analysis of the alcohol-treated rat erythrocyte membranes revealed altered membrane individual phospholipid contents and fluidity properties. Alcohol-induced morphological changes in the erythrocytes and its effect on decreasing the resistance of hypotonic shock induced by NaCl are evident from the hemolysis curves. However, AETA administration to alcoholic rats beneficially modulated the membrane properties anvd protected erythrocytes from damage.

Conclusion

Results suggest that AETA protects erythrocytes from alcohol-induced oxidative stress, biophysical, and biochemical changes very effectively.

Patients with Alcoholic Liver Disease Have Worse Functional Status at Time of Liver Transplant Registration and Greater Waitlist and Post-transplant Mortality Which Is Compounded by Older Age

BACKGROUND

Worse functional status correlates with increased mortality on the liver transplant (LT) waitlist. Whether functional status affects LT outcomes equally across cirrhosis etiologies is unclear.

AIMS

We evaluate the impact of functional status on waitlist and post-LT mortality stratified by etiology and age.

METHODS

Functional status among US adults from 2005 to 2017 United Network for Organ Sharing LT registry data was retrospectively evaluated using Karnofsky Performance Status Score (KPS-1 = functional status 80-100%, KPS-2 = 60-70%, KPS-3 = 40-50%, KPS-4 = 10-30%). Waitlist and post-LT survival were stratified by KPS and cirrhosis etiology, including alcoholic liver disease (ALD), nonalcoholic steatohepatitis (NASH), hepatitis C (HCV), and HCV/ALD, and evaluated using Kaplan-Meier and multivariate Cox proportional hazard models.

RESULTS

Among 94,201 waitlist registrants (69.4% men, 39.5% HCV, 26.7% ALD, 23.2% NASH), ALD patients had worse functional status compared to HCV (KPS-4: 17.2% vs. 8.3%, p < 0.001). Worse functional status at time of waitlist registration was associated with higher 90-day waitlist mortality with the greatest effect in ALD (KPS-4 vs. KPS-1: ALD HR 2.16, 95% CI 1.83-2.55; HCV HR 2.17, 95% CI 1.87-2.51). Similar trends occurred in 5-year post-LT survival with ALD patients the most harmed. Compared to patients < 50 years, patients ≥ 65 years had increased waitlist mortality at 90-days if they had HCV or HCV/ALD, and 5-year post-LT mortality regardless of cirrhosis etiology with ALD patients most severely affected.

CONCLUSIONS

In a retrospective cohort study of patients, US ALD patients had disparately worse functional status at time of LT waitlist registration. Worse functional status correlated with higher risk of waitlist and post-LT mortality, affecting ALD and HCV patients the most.

Alcohol Consumption Reduces the Beneficial Influence of Protein Intake on Muscle Mass in Middle-Aged Korean Adults: A 12-Year Community-Based Prospective Cohort Study

The influence of alcohol consumption on the association of protein intake with muscle mass was assessed using data from the Korean Genome and Epidemiology Study. Dietary protein intakes of 4412 middle-aged participants with normal baseline muscle mass were assessed using a semi-quantitative Food Frequency Questionnaire, and baseline alcohol consumption data (e.g., frequency and amount) were collected using a structured questionnaire. The skeletal muscle mass index (SMI), defined as the weight-adjusted skeletal muscle mass, was measured using multi-frequency bioelectrical impedance analyses every 2 years until the study endpoint. Low muscle mass was defined as a SMI <2 standard deviations below the sex-specific normal mean for a young reference group. During a 12-year follow-up, 395 subjects developed a low SMI. After multivariate adjustments, high protein intake (≥1.2 g/kg body weight (BW)) was shown to reduce the risk of low SMI development in both men (hazard ratio (HR): 0.24; 95% confidence interval (CI): 0.12, 0.51; p for trend < 0.001) and women (HR: 0.29; 95% CI: 0.16, 0.53; p for trend < 0.001), compared with low protein intake (<0.8 g/kg BW). Alcohol consumption attenuated the protective influence of protein intake against low SMI development in women (HR: 0.64; 95% CI: 0.18, 2.25; p for trend = 0.478). Among the total subjects, heavy drinkers with high protein intake were not significantly associated with the development of a low SMI (HR: 0.20; 95% CI: 0.03, 1.50; p = 0.117). Additional research should clarify the dose-response effects of alcohol consumption on muscle mass relative to daily protein intake.

Cellular and molecular signatures of alcohol-induced myopathy in women

Alcoholic myopathy is characterized by the reduction in cross-sectional area (CSA) of muscle fibers and impaired anabolic signaling. The goal of the current study was to investigate the causes and compare the changes in CSA and fiber type composition with the modifications of anabolic and catabolic signaling pathways at the early stages of chronic alcohol consumption in women. Skeletal muscle samples from 5 female patients with alcohol abuse (AL; 43 ± 5 yr old; alcohol abuse duration 5,6 ± 0,6 yr) were compared with the muscle from the control group of 8 healthy women (C; 35 ± 4 yr old). The average daily dose of alcohol consumption was 110 ± 10 ml of pure ethanol. In women patients, a significant decrease in CSA of type I and II muscle fibers, titin and nebulin content, plasma IGF-1 level and total IRS-1, p-Akt and p-4E-BP1 in vastus lateralis was found in comparison with the control group. The p-AMPK level was found to be increased versus the control group. In women patients with chronic alcoholic myopathy 1) both fast and slow muscle fibers are subjected to atrophy; 2) impairments in IGF-I-dependent signaling and pathways controlling translation initiation (AMPK/mTOR/4E-BP1), but not translation elongation, are observed; 3) the level of calpain-1 and ubiquitinated proteins increases, unlike E3 ligases content.

Cholecalciferol in ethanol-preferring rats muscle fibers increases the number and area of type II fibers

The chronic use of ethanol causes neuropathy and atrophy of type II fibers and promotes vitamin D decrease. This study evaluated cholecalciferol effects on the deep fibular nerve and extensor digitorum longus (EDL) muscle using an UChB ethanol-preferring rats model. Blood analyses were carried out to measure levels of 25-hydroxycholecalciferol (25(OH)D), calcium (Ca²⁺), Phosphorus (P), and parathyroid hormone (PTH). It was used EDL muscle to evaluate oxidative stress. The deep fibular nerve and EDL muscle were used for morphologic and morphometric assessment. 25(OH)D plasma levels were higher in the supplemented group and no alterations were observed in other parameters including the oxidative stress evaluation. The G ratio remained constant which indicates nervous conduction normality. Cholecalciferol supplementation promoted an increase in the number and area of type II fibers and a decrease in the area of type I fibers. In the studied model, there was neither alcoholic myopathy nor neuropathy. The EDL muscle glycolytic patterns in the high-drinker UChB rats may be associated with the differential effects of cholecalciferol on metabolism and protein synthesis in skeletal muscle.

Effect of Chronic Alcohol Abuse on Anabolic and Catabolic Signaling Pathways in Human Skeletal Muscle

BACKGROUND

Animal studies showed that alcoholic myopathy is characterized by the reduction in myofiber cross-sectional area (CSA) and by impaired anabolic signaling. The goal of this study was to compare changes in CSA and fiber type composition with modifications in anabolic and catabolic signaling pathways at the early stages of alcohol misuse in humans.

METHODS

Skeletal muscle samples from 7 male patients with chronic alcohol abuse (AL; 47.7 ± 2.0 years old; alcohol misuse duration 7.7 ± 0.6 years) were compared with muscle from a control group of 7 healthy men (C; 39.7 ± 5.0 years old). Biopsies from vastus lateralis muscles were taken and analyzed for the changes in fiber type composition, fiber CSA, and for the alterations in anabolic and catabolic signaling pathways.

RESULTS

AL patients did not have detectable clinical myopathy symptoms or muscle fiber atrophy, but the relative proportion of fast fibers was increased. There was a significant decrease in IGF-1 in plasma and IRS-1 protein content in muscle of AL group. Levels of total and phosphorylated p70S6K1, GSK3β, and p90RSK1 were not different between AL and C groups. Muscle of AL patients had increased mRNA expression of HSP70 and HSP90. A marker of anabolic pathway p-4E-BP1 was decreased, while catabolic markers (MuRF-1, MAFbx, ubiquitinated proteins) were increased in AL patients when compared with C group.

CONCLUSIONS

At the early stages of alcohol misuse in humans, changes in the regulation of anabolic and catabolic signaling pathways precede the development of skeletal muscle atrophy and manifestation of clinical symptoms of alcoholic myopathy.

Organ-Organ Crosstalk and Alcoholic Liver Disease

Alcohol consumption is a common custom worldwide, and the toxic effects of alcohol on several target organs are well-understood. Given the poor prognosis of treating clinically-relevant alcoholic liver disease (ALD) (i.e., alcoholic hepatitis (AH) and cirrhosis), additional research is required to develop more effective therapies. While the stages of ALD have been well-characterized, targeted therapies to prevent or reverse this process in humans are still needed. Better understanding of risk factors and mechanisms underlying disease progression can lead to the development of rational therapies to prevent or reverse ALD in the clinic. A potential area of targeted therapy for ALD may be organ–organ communication in the early stages of the disease. In contrast to AH and end-stage liver diseases, the involvement of multiple organs in the development of ALD is less understood. The impact of these changes on pathology to the liver and other organs may not only influence disease progression during the development of the disease, but also outcomes of end stages diseases. The purpose of this review is to summarize the established and proposed communication between the liver and other organ systems that may contribute to the development and progression of liver disease, as well as to other organs. Potential mechanisms of this organ–organ communication are also discussed.

High prevalence of sarcopenia among binge drinking elderly women: a nationwide population-based study

Background

Alcohol consumption is considered a risk factor for sarcopenia, but the association between alcohol consumption and the prevalence of sarcopenia has not been evaluated in detail. This study was to identify the relationship between alcohol drinking patterns and the prevalence of sarcopenia in the elderly Korean population.

Methods

The cross-sectional study was performed using data from the Korea National Health and Nutrition Examination Survey. Participants were excluded if they were under the age of 65, or if data was not available regarding skeletal muscle mass or dietary intake. After these exclusions, a total of 4020 participants (men: 1698; women: 2322) were analyzed in the present study. Sarcopenia is defined according to the criteria for the Asia Working Group for Sarcopenia (AWGS). Binge drinking was defined as consuming ≥5 standard alcoholic drinks (≥4 drinks for women) consecutively on one occasion. This data was subcategorized into two groups based on presence of binge drinking: Social drinking (≤1 time/month) and binge drinking (>1 time/month).

Results

Women binge drinkers with weekly or daily consumption had 2.8 times higher prevalence of sarcopenia than social drinkers (Odds Ratio [OR] = 2.84; 95% Confidence Interval [CI] = 1.12–7.29). However, there were no associations between binge drinkers and sarcopenia in men. After adjusting for age, body mass index (BMI), energy intake, moderate physical activity, and energy intake, women binge drinkers with weekly or daily alcohol consumption had 3.9 times higher prevalence of sarcopenia than social drinkers (OR = 3.88; 95% CI = 1.33–11.36).

Conclusions

The prevalence of sarcopenia in elderly women was related to binge drinking frequency and amounts of drinking after adjusting for covariates. Elderly Korean women who binge drink once or more per week may be associated with sarcopenia, as seen with the observed 3.9 times higher prevalence compared to social drinkers.

Transitional Remodeling of the Hepatic Extracellular Matrix in Alcohol-Induced Liver Injury

Alcohol consumption is a common custom worldwide, and the toxic effects of alcohol on several target organs are well understood. The liver is the primary site of alcohol metabolism and is therefore the major target of alcohol toxicity. Alcoholic liver disease is a spectrum of disease states, ranging from simple steatosis (fat accumulation), to inflammation, and eventually to fibrosis and cirrhosis if untreated. The fibrotic stage of ALD is primarily characterized by robust accumulation of extracellular matrix (ECM) proteins (collagens) which ultimately impairs the function of the organ. The role of the ECM in early stages of ALD is poorly understood, but recent research has demonstrated that a number of changes in the hepatic ECM in prefibrotic ALD not only are present, but may also contribute to disease progression. The purpose of this review is to summarize the established and proposed changes to the hepatic extracellular matrix (ECM) that may contribute to earlier stages of ALD development and to discuss potential mechanisms by which these changes may mediate the progression of the disease.

Heavy Alcohol Consumption with Alcoholic Liver Disease Accelerates Sarcopenia in Elderly Korean Males: The Korean National Health and Nutrition Examination Survey 2008-2010

Background and Aim

Although a few studies have reported that sarcopenia is associated with alcoholic liver disease (ALD), no studies have investigated this association in a large sample representative of the elderly Korean population.

Methods

This was a cross-sectional study that used data from the Fourth and Fifth Korean National Health and Nutrition Examination Surveys (KNHANES) on subjects aged 65 years and older. Sarcopenia was defined as a skeletal muscle index (SMI) more than 1 SD below the gender-specific mean for young adults; SMI was calculated as the appendicular muscle mass divided by height squared (ASM/Ht²). Heavy alcohol consumption was defined as consuming at least 210 g/week, and elevated liver enzymes were defined as alanine aminotransferase levels of at least 32 U/L or aspartate aminotransferase levels of at least 34 U/L. ALD was defined as heavy alcohol consumption and elevated liver enzymes.

Results

The mean age of the 1,151 elderly males was 71.6 ± 0.2 years, and the prevalence of heavy alcohol consumption was 11.8% (136 subjects). SMI did not differ between the non-heavy and heavy alcohol consumer groups (7.1 ± 0.0 kg/m² vs. 7.3 ± 0.1 kg/m², respectively, P = 0.145). However, after stratifying by the presence of liver disease and heavy alcohol consumption and adjusting for other confounders in the multivariate logistic regression, SMI was significantly lower among heavy alcohol consumers with ALD (all P < 0.05). Additionally, two-way ANOVA showed a significant interaction between heavy alcohol consumption and liver disease (P = 0.011).

Conclusion

Sarcopenia was accelerated in the elderly male ALD group, with a significant interaction between alcohol consumption and liver disease.

Alcoholism: A systemic proinflammatory condition

Excessive ethanol consumption affects virtually any organ, both by indirect and direct mechanisms. Considerable research in the last two decades has widened the knowledge about the paramount importance of proinflammatory cytokines and oxidative damage in the pathogenesis of many of the systemic manifestations of alcoholism. These cytokines derive primarily from activated Kupffer cells exposed to Gram-negative intestinal bacteria, which reach the liver in supra-physiological amounts due to ethanol-mediated increased gut permeability. Reactive oxygen species (ROS) that enhance the inflammatory response are generated both by activation of Kupffer cells and by the direct metabolic effects of ethanol. The effects of this increased cytokine secretion and ROS generation lie far beyond liver damage. In addition to the classic consequences of endotoxemia associated with liver cirrhosis that were described several decades ago, important research in the last ten years has shown that cytokines may also induce damage in remote organs such as brain, bone, muscle, heart, lung, gonads, peripheral nerve, and pancreas. These effects are even seen in alcoholics without significant liver disease. Therefore, alcoholism can be viewed as an inflammatory condition, a concept which opens the possibility of using new therapeutic weapons to treat some of the complications of this devastating and frequent disease. In this review we examine some of the most outstanding consequences of the altered cytokine regulation that occurs in alcoholics in organs other than the liver.

Human alcohol-related neuropathology

Alcohol-related diseases of the nervous system are caused by excessive exposures to alcohol, with or without co-existing nutritional or vitamin deficiencies. Toxic and metabolic effects of alcohol (ethanol) vary with brain region, age/developmental stage, dose, and duration of exposures. In the mature brain, heavy chronic or binge alcohol exposures can cause severe debilitating diseases of the central and peripheral nervous systems, and skeletal muscle. Most commonly, long-standing heavy alcohol abuse leads to disproportionate loss of cerebral white matter and impairments in executive function. The cerebellum (especially the vermis), cortical-limbic circuits, skeletal muscle, and peripheral nerves are also important targets of chronic alcohol-related metabolic injury and degeneration. Although all cell types within the nervous system are vulnerable to the toxic, metabolic, and degenerative effects of alcohol, astrocytes, oligodendrocytes, and synaptic terminals are major targets, accounting for the white matter atrophy, neural inflammation and toxicity, and impairments in synaptogenesis. Besides chronic degenerative neuropathology, alcoholics are predisposed to develop severe potentially life-threatening acute or subacute symmetrical hemorrhagic injury in the diencephalon and brainstem due to thiamine deficiency, which exerts toxic/metabolic effects on glia, myelin, and the microvasculature. Alcohol also has devastating neurotoxic and teratogenic effects on the developing brain in association with fetal alcohol spectrum disorder/fetal alcohol syndrome. Alcohol impairs function of neurons and glia, disrupting a broad array of functions including neuronal survival, cell migration, and glial cell (astrocytes and oligodendrocytes) differentiation. Further progress is needed to better understand the pathophysiology of this exposure-related constellation of nervous system diseases and better correlate the underlying pathology with in vivo imaging and biochemical lesions.

Human alcohol-related neuropathology

Alcohol-related diseases of the nervous system are caused by excessive exposures to alcohol, with or without co-existing nutritional or vitamin deficiencies. Toxic and metabolic effects of alcohol (ethanol) vary with brain region, age/developmental stage, dose, and duration of exposures. In the mature brain, heavy chronic or binge alcohol exposures can cause severe debilitating diseases of the central and peripheral nervous systems, and skeletal muscle. Most commonly, long-standing heavy alcohol abuse leads to disproportionate loss of cerebral white matter and impairments in executive function. The cerebellum (especially the vermis), cortical-limbic circuits, skeletal muscle, and peripheral nerves are also important targets of chronic alcohol-related metabolic injury and degeneration. Although all cell types within the nervous system are vulnerable to the toxic, metabolic, and degenerative effects of alcohol, astrocytes, oligodendrocytes, and synaptic terminals are major targets, accounting for the white matter atrophy, neural inflammation and toxicity, and impairments in synaptogenesis. Besides chronic degenerative neuropathology, alcoholics are predisposed to develop severe potentially life-threatening acute or subacute symmetrical hemorrhagic injury in the diencephalon and brainstem due to thiamine deficiency, which exerts toxic/metabolic effects on glia, myelin, and the microvasculature. Alcohol also has devastating neurotoxic and teratogenic effects on the developing brain in association with fetal alcohol spectrum disorder/fetal alcohol syndrome. Alcohol impairs function of neurons and glia, disrupting a broad array of functions including neuronal survival, cell migration, and glial cell (astrocytes and oligodendrocytes) differentiation. Further progress is needed to better understand the pathophysiology of this exposure-related constellation of nervous system diseases and better correlate the underlying pathology with in vivo imaging and biochemical lesions.

Effect of neuromuscular electrical stimulation in glycogen muscle reserves because of ingestion of ethanol: a study in rats

OBJECTIVE

To evaluate the effects of alcoholic ingestion and neurostimulation on the muscle glycogen reserve, body weight, blood sugar, and weight of the soleus muscle.

METHODS

Twenty male rats were distributed into four experimental groups (n=5), namely, Control, Ethanol, Electrostimulated, and Ethanol+Electrostimulated. The study lasted for 22 days. The groups submitted to the use of ethanol received the substance diluted in water, which was consumed during the entire experimental period. The groups that received electrostimulation, undersedationfor the procedure, had their left hind leg shaved, and the current was applied daily for 7 days, in 20-minute sessions. Next, after induced alcoholism and electrical stimulation in the corresponding groups, the animals were euthanized so that their muscles could be sent for glycogen analysis.

RESULTS

The Ethanol group displayed a lower body weight when compared to the Control and Electrostimulated groups; the Ethanol+Electrostimulated groups had a lower body weight compared to the Control and Electrostimulated groups, but were in a better situation when compared to the Ethanol group. As to glycogen capture, it was noted that the Ethanol group demonstrated resistance to blood glucose capture, whereas the Ethanol Electrostimulated group showed better capture than the other groups. As to muscle weight, it was observed that the Ethanol group had a lower weight than did the Controls, and that the Electrostimulated group weight greater when compared to the Control and Ethanol groups, respectively. On the other hand, the Ethanol+Electrostimulated groups showed no significant difference relative to the Controls, but had better results when compared to the Ethanol group.

CONCLUSIONS

Chronic exposure to alcohol showed a direct relationship with reduced muscle and body weight, and in glycogen capture and muscle reserves, besides favoring innumerous organic disorders, thus interfering in rehabilitation processes.

A dynamic plasma membrane proteome analysis of alcohol-induced liver cirrhosis

Alcohol-induced injury has become one of the major causes for liver cirrhosis. However, the molecular mechanisms of ethanol-induced injury are not fully understood. To this end, we performed a dynamic plasma membrane proteomic research on rat model. A rat model from hepatitis to liver cirrhosis was developed. Plasma membrane from liver tissue with liver fibrosis stage of 2 and 4 (S2 and S4) was purified by sucrose density gradient centrifugation. Its purification was verified by western blotting. Proteins from plasma membrane were separated by two-dimensional electrophoresis (2DE) and differentially expressed proteins were identified by tandem mass spectrometry. 16 consistent differentially expressed proteins from S2 to S4 were identified by mass spectrometry. The expression of differentially expressed proteins annexin A6 and annexin A3 were verified by western blotting, and annexin A3 was futher verified by immunohistochemistry. Our research suggests a possible mechanism by which ethanol alters protein expression to enhance the liver fibrosis progression. These differentially expressed proteins might be new drug targets for treating alcoholic liver cirrhosis.

Plasma membrane proteome analysis of the early effect of alcohol on liver: implications for alcoholic liver disease

In humans, the over-consumption of alcohol can lead to serious liver disease. To examine the early effects of alcohol on liver disease, rats were given sufficient ethanol to develop liver cirrhosis. Rats before the onset of fibrosis were studied in this work. Plasma membranes (PM) of liver were extracted by twice sucrose density gradient centrifugation. The proteome profiles of PM from ethanol-treated rats and the controls were analyzed using two-dimensional gel electrophoresis (2-DE) and isobaric tag for relative and absolute quantitation (iTRAQ) technology. Ethanol treatment altered the amount of 15 different liver proteins: 10 of them were detected by 2-DE and 5 by iTRAQ. Keratin 8 was detected by both methods. Gene ontology analysis of these differentially detected proteins indicated that most of them were involved in important cell functions such as binding activity (including ion, DNA, ATP binding, etc.), cell structure, or enzyme activity. Among these, annexin A2, keratin 8, and keratin 18 were further verified using western blot analysis and annexin A2 was verified by immunohistochemistry. Our results suggested that alcohol has the potential to affect cell structure, adhesion and enzyme activity by altering expression levels of several relevant proteins in the PM. To the best of our knowledge, this is the first time to study the effect of alcohol on the liver PM proteome and it might be helpful for understanding the possible mechanisms of alcohol-induced liver disease.

Ethanol decreases agrin-induced acetylcholine receptor clustering in C2C12 myotube culture

We investigated the effect of ethanol on skeletal muscle development using C2C12 cell culture. The ethanol concentrations of 10mM, 25mM, and 100mM, were tested because plasma samples of alcohol-dependent individuals fall within this range. We assessed two specific events in skeletal muscle development, the fusion of myoblasts to form myotubes and the acetylcholine receptor (AChR) clustering associated with neuromuscular synapse formation. We report that ethanol does not effect myotube formation or the viability of myoblasts or myotubes in C2C12 cell culture. However, ethanol does effect AChR clustering on C2C12 myotubes. As motor neurons approach skeletal muscle during development, agrin is released by motor neurons and induces AChR clustering on muscle fibers. In our experiments, agrin was applied to cell cultures during the period when myoblasts fuse to form myotubes. In cell cultures exposed to ethanol during myotube formation, agrin-induced AChR clustering was decreased compared to untreated cultures. In cell cultures exposed to ethanol during myoblast proliferation, with ethanol removed during myotube formation, agrin-induced AChR clustering was unaffected. We conclude that exposure to a physiologically relevant concentration of ethanol during the specific period of myotube formation decreases agrin-induced AChR clustering.

Biochemical and neurotransmitter changes implicated in alcohol-induced brain damage in chronic or 'binge drinking' alcohol abuse

The brain damage, which occurs after either chronic alcoholization or binge drinking regimes, shows distinct biochemical and neurotransmitter differences. An excessive amount of glutamate is released into specific brain regions during binge drinking (in excess of 4- to 5-fold of the normal basal concentration) that is not evident during periods of excessive alcohol consumption in chronic alcohol abusers. Increases in glutamate release are only observed during the initial stages of withdrawal from chronic alcoholism ( approximately 2- to 3-fold) due to alterations in the sensitivities of the NMDA receptors. Such changes in either density or sensitivity of these receptors are reported to be unaltered by binge drinking. When such excesses of glutamate are released in these two different models of alcohol abuse, a wide range of biochemical changes occur, mediated in part by increased fluxes of calcium ions and/or activation of various G-protein-associated signalling pathways. Cellular studies of alveolar macrophages isolated from these two animal models of alcohol abuse showed enhanced (binge drinking) or reduced (chronic alcoholization) lipopolysaccharide (LPS)-stimulated NO release. Such studies could suggest that neuroadaptation occurs with the development of tolerance to alcohol's effects in both neurotransmitter function and cellular processes during chronic alcoholization that delay the occurrence of brain damage. In contrast, 'binge drinking' induces immediate and toxic effects and there is no evidence of an increased preference for alcohol as seen after withdrawal from chronic alcoholization.

Molecular and cellular events in alcohol-induced muscle disease

Alcohol consumption induces a dose-dependent noxious effect on skeletal muscle, leading to progressive functional and structural damage of myocytes, with concomitant reductions in lean body mass. Nearly half of high-dose chronic alcohol consumers develop alcoholic skeletal myopathy. The pathogenic mechanisms that lie between alcohol intake and loss of muscle tissue involve multiple pathways, making the elucidation of the disease somewhat difficult. This review discusses the recent advances in basic and clinical research on the molecular and cellular events involved in the development of alcohol-induced muscle disease. The main areas of recent research interest on this field are as follows: (i) molecular mechanisms in alcohol exposed muscle in the rat model; (ii) gene expression changes in alcohol exposed muscle; (iii) the role of trace elements and oxidative stress in alcoholic myopathy; and (iv) the role of apoptosis and preapoptotic pathways in alcoholic myopathy. These aforementioned areas are crucial in understanding the pathogenesis of this disease. For example, there is overwhelming evidence that both chronic alcohol ingestion and acute alcohol intoxication impair the rate of protein synthesis of myofibrillar proteins, in particular, under both postabsorptive and postprandial conditions. Perturbations in gene expression are contributory factors to the development of alcoholic myopathy, as ethanol-induced alterations are detected in over 400 genes and the protein profile (i.e., the proteome) of muscle is also affected. There is supportive evidence that oxidative damage is involved in the pathogenesis of alcoholic myopathy. Increased lipid peroxidation is related to muscle fibre atrophy, and reduced serum levels of some antioxidants may be related to loss of muscle mass and muscle strength. Finally, ethanol induces skeletal muscle apoptosis and increases both pro- and antiapoptotic regulatory mechanisms.

Oxidative stress, chronic disease, and muscle wasting

Underlying the pathogenesis of chronic disease is the state of oxidative stress. Oxidative stress is an imbalance in oxidant and antioxidant levels. If an overproduction of oxidants overwhelms the antioxidant defenses, oxidative damage of cells, tissues, and organs ensues. In some cases, oxidative stress is assigned a causal role in disease pathogenesis, whereas in others the link is less certain. Along with underlying oxidative stress, chronic disease is often accompanied by muscle wasting. It has been hypothesized that catabolic programs leading to muscle wasting are mediated by oxidative stress. In cases where disease is localized to the muscle, this concept is easy to appreciate. Transmission of oxidative stress from diseased remote organs to skeletal muscle is thought to be mediated by humoral factors such as inflammatory cytokines. This review examines the relationship between oxidative stress, chronic disease, and muscle wasting, and the mechanisms by which oxidative stress acts as a catabolic signal.

Erythrocyte and plasma protein modification in alcoholism: A possible role of acetaldehyde

Analysis of the oxidative modification of plasma and erythrocyte ghost proteins of chronic alcoholic subjects and healthy non-alcoholics has been performed. It was found that increased levels of protein carbonyls in both plasma and erythrocyte ghosts from alcoholic subjects occurred in comparison to the levels found in preparations from non-alcoholics. Plasma proteins from alcoholic subjects did not show evidence of cross-linking, although plasma protein concentration and composition were changed. In alcoholic subjects who displayed no evidence of abnormal erythrocyte morphology no cross-linking of erythrocyte ghost proteins was detectable, whereas the ghosts obtained from alcoholic subjects who displayed morphologically abnormal erythrocytes contained cross-linked proteins. The in vitro treatment with acetaldehyde of erythrocytes from non-alcoholics caused increased levels of protein carbonyls and cross-linking products in erythrocyte ghost preparations which were similar to those found in severe alcoholics. It is concluded that chronic alcohol consumption can cause abnormal erythrocyte morphology and increased erythrocyte fragility as a result of oxidation and cross-linking of erythrocyte ghost proteins. These effects can be ascribed, in part, to exposure of erythrocytes to circulatory acetaldehyde which is a product of ethanol metabolism.

Limited effects of combined dietary copper deficiency/iron overload on oxidative stress parameters in rat liver and plasma

Copper (Cu) deficiency decreases the activity of Cu-dependent antioxidant enzymes such as Cu,zinc-superoxide dismutase (Cu,Zn-SOD) and may be associated with increased susceptibility to oxidative stress. Iron (Fe) overload represents a dietary oxidative stress relevant to overuse of Fe-containing supplements and to hereditary hemochromatosis. In a study to investigate oxidative stress interactions of dietary Cu deficiency with Fe overload, weanling male Long-Evans rats were fed one of four sucrose-based modified AIN-93G diets formulated to differ in Cu (adequate 6 mg/kg diet vs. deficient 0.5 mg/kg) and Fe (adequate 35 mg/kg vs. overloaded 1500 mg/kg) in a 2 x 2 factorial design for 4 weeks prior to necropsy. Care was taken to minimize oxidation of the diets prior to feeding to the rats. Liver and plasma Cu content and liver Cu,Zn-SOD activity declined with Cu deficiency and liver Fe increased with Fe overload, confirming the experimental dietary model. Liver thiobarbituric acid reactive substances were significantly elevated with Fe overload (pooled across Cu treatments, 0.80+/-0.14 vs. 0.54+/-0.08 nmol/mg protein; P<.0001) and not affected by Cu deficiency. Liver cytosolic protein carbonyl content and the concentrations of several oxidized cholesterol species in liver tissue did not change with these dietary treatments. Plasma protein carbonyl content decreased in Cu-deficient rats and was not influenced by dietary Fe overload. The various substrates (lipid, protein and cholesterol) appeared to differ in their susceptibility to the in vivo oxidative stress induced by dietary Fe overload, but these differences were not exacerbated by Cu deficiency.