Role of HIF-1α in Alcohol-Mediated Multiple Organ Dysfunction

Pioglitazone reverses alcohol-induced alterations in alveolar macrophage mitochondrial phenotype

BACKGROUND

People with alcohol use disorder (AUD) have an increased risk of developing pneumonia and pulmonary diseases. Alveolar macrophages (AMs) are immune cells of the lower respiratory tract that are necessary for clearance of pathogens. However, alcohol causes AM oxidative stress, mitochondrial damage and dysfunction, and diminished phagocytic capacity, leading to lung injury and immune suppression.

METHODS

AMs were isolated by bronchoalveolar lavage from people with AUD and male and female C57BL/6J mice given chronic ethanol (20% w/v, 12 weeks) in drinking water. The peroxisome proliferator-activated receptor γ ligand, pioglitazone, was used to treat human AMs ex vivo (10 μM, 24 h) and mice in vivo by oral gavage (10 mg/kg/day). Levels of AM mitochondrial superoxide and hypoxia-inducible factor-1 alpha (HIF-1α) mRNA, a marker of oxidative stress, were measured by fluorescence microscopy and RT-qPCR, respectively. Mouse AM phagocytic ability was determined by internalized Staphylococcus aureus, and mitochondrial capacity, dependency, and flexibility for glucose, long-chain fatty acid, and glutamine oxidation were measured using an extracellular flux analyzer. In vitro studies used a murine AM cell line, MH-S (±0.08% ethanol, 72 h) to investigate mitochondrial fuel oxidation and ATP-linked respiration.

RESULTS

Pioglitazone treatment decreased mitochondrial superoxide in AMs from people with AUD and ethanol-fed mice and HIF-1α mRNA in ethanol-fed mouse lungs. Pioglitazone also reversed mouse AM glutamine oxidation and glucose or long-chain fatty acid flexibility to meet basal oxidation needs. In vitro, ethanol decreased the rate of AM mitochondrial and total ATP production, and pioglitazone improved changes in glucose and glutamine oxidation.

CONCLUSIONS

Pioglitazone reversed chronic alcohol-induced oxidative stress in human AM and mitochondrial substrate oxidation flexibility and superoxide levels in mouse AM. Decreased ethanol-induced AM HIF-1α mRNA with pioglitazone suggests that this pathway may be a focus for metabolic-targeted therapeutics to improve morbidity and mortality in people with AUD.

Genetic factors associated with suicidal behaviors and alcohol use disorders in an American Indian population

American Indians (AI) demonstrate the highest rates of both suicidal behaviors (SB) and alcohol use disorders (AUD) among all ethnic groups in the US. Rates of suicide and AUD vary substantially between tribal groups and across different geographical regions, underscoring a need to delineate more specific risk and resilience factors. Using data from over 740 AI living within eight contiguous reservations, we assessed genetic risk factors for SB by investigating: (1) possible genetic overlap with AUD, and (2) impacts of rare and low-frequency genomic variants. Suicidal behaviors included lifetime history of suicidal thoughts and acts, including verified suicide deaths, scored using a ranking variable for the SB phenotype (range 0-4). We identified five loci significantly associated with SB and AUD, two of which are intergenic and three intronic on genes AACSP1, ANK1, and FBXO11. Nonsynonymous rare and low-frequency mutations in four genes including SERPINF1 (PEDF), ZNF30, CD34, and SLC5A9, and non-intronic rare and low-frequency mutations in genes OPRD1, HSD17B3 and one lincRNA were significantly associated with SB. One identified pathway related to hypoxia-inducible factor (HIF) regulation, whose 83 nonsynonymous rare and low-frequency variants on 10 genes were significantly linked to SB as well. Four additional genes, and two pathways related to vasopressin-regulated water metabolism and cellular hexose transport, also were strongly associated with SB. This study represents the first investigation of genetic factors for SB in an American Indian population that has high risk for suicide. Our study suggests that bivariate association analysis between comorbid disorders can increase statistical power; and rare and low-frequency variant analysis in a high-risk population enabled by whole-genome sequencing has the potential to identify novel genetic factors. Although such findings may be population specific, rare functional mutations relating to PEDF and HIF regulation align with past reports and suggest a biological mechanism for suicide risk and a potential therapeutic target for intervention.

Direct effects of alcohol on gut-epithelial barrier: Unraveling the disruption of physical and chemical barrier of the gut-epithelial barrier that compromises the host-microbiota interface upon alcohol exposure

The development of alcohol-associated diseases is multifactorial, mechanism of which involves metabolic alteration, dysregulated immune response, and a perturbed intestinal host-environment interface. Emerging evidence has pinpointed the critical role of the intestinal host-microbiota interaction in alcohol-induced injuries, suggesting its contribution to disease initiation and development. To maintain homeostasis in the gut, the intestinal mucosa serves as the first-line defense against exogenous factors in the gastrointestinal tract, including dietary contents and the commensal microbiota. The gut-epithelial barrier comprises a physical barrier lined with a single layer of intestinal epithelial cells and a chemical barrier with mucus trapping host regulatory factors and gut commensal bacteria. In this article, we review recent studies pertaining to the disrupted gut-epithelial barrier upon alcohol exposure and examine how alcohol and its metabolism can affect the regulatory ability of intestinal epithelium.

Effect of Postnatal Epigallocatechin-Gallate Treatment on Cardiac Function in Mice Prenatally Exposed to Alcohol

Prenatal alcohol exposure affects the cardiovascular health of the offspring. Epigallocatechin-3-gallate (EGCG) may be a protective agent against it, but no data are available regarding its impact on cardiac dysfunction. We investigated the presence of cardiac alterations in mice prenatally exposed to alcohol and the effect of postnatal EGCG treatment on cardiac function and related biochemical pathways. C57BL/6J pregnant mice received 1.5 g/kg/day (Mediterranean pattern), 4.5 g/kg/day (binge pattern) of ethanol, or maltodextrin until Day 19 of pregnancy. Post-delivery, treatment groups received EGCG-supplemented water. At post-natal Day 60, functional echocardiographies were performed. Heart biomarkers of apoptosis, oxidative stress, and cardiac damage were analyzed by Western blot. BNP and Hif1α increased and Nrf2 decreased in mice prenatally exposed to the Mediterranean alcohol pattern. Bcl-2 was downregulated in the binge PAE drinking pattern. Troponin I, glutathione peroxidase, and Bax increased in both ethanol exposure patterns. Prenatal alcohol exposure led to cardiac dysfunction in exposed mice, evidenced by a reduced ejection fraction, left ventricle posterior wall thickness at diastole, and Tei index. EGCG postnatal therapy restored the physiological levels of these biomarkers and improved cardiac dysfunction. These findings suggest that postnatal EGCG treatment attenuates the cardiac damage caused by prenatal alcohol exposure in the offspring.

Bioactive Compounds as Inhibitors of Inflammation, Oxidative Stress and Metabolic Dysfunctions via Regulation of Cellular Redox Balance and Histone Acetylation State

Bioactive compounds (BCs) are known to exhibit antioxidant, anti-inflammatory, and anti-cancer properties by regulating the cellular redox balance and histone acetylation state. BCs can control chronic oxidative states caused by dietary stress, i.e., alcohol, high-fat, or high-glycemic diet, and adjust the redox balance to recover physiological conditions. Unique functions of BCs to scavenge reactive oxygen species (ROS) can resolve the redox imbalance due to the excessive generation of ROS. The ability of BCs to regulate the histone acetylation state contributes to the activation of transcription factors involved in immunity and metabolism against dietary stress. The protective properties of BCs are mainly ascribed to the roles of sirtuin 1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (NRF2). As a histone deacetylase (HDAC), SIRT1 modulates the cellular redox balance and histone acetylation state by mediating ROS generation, regulating nicotinamide adenine dinucleotide (NAD+)/NADH ratio, and activating NRF2 in metabolic progression. In this study, the unique functions of BCs against diet-induced inflammation, oxidative stress, and metabolic dysfunction have been considered by focusing on the cellular redox balance and histone acetylation state. This work may provide evidence for the development of effective therapeutic agents from BCs.

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.

A critical review of recent knowledge of alcohol's effects on the immunological response in different tissues

Alcohol misuse contributes to the dysregulation of immune responses and multiorgan dysfunction across various tissues, which are associated with higher risk of morbidity and mortality in people with alcohol use disorders. Organ-specific immune cells, including microglia in the brain, alveolar macrophages in the lungs, and Kupffer cells in the liver, play vital functions in host immune defense through tissue repair and maintenance of homeostasis. However, binge drinking and chronic alcohol misuse impair these immune cells' abilities to regulate inflammatory signaling and metabolism, thus contributing to multiorgan dysfunction. Further complicating these delicate systems, immune cell dysfunction associated with alcohol misuse is exacerbated by aging and gut barrier leakage. This critical review describes recent advances in elucidating the potential mechanisms by which alcohol misuse leads to derangements in host immunity and highlights current gaps in knowledge that may be the focus of future investigations.

Lactobacillus plantarum ST-III culture supernatant ameliorates alcohol-induced cognitive dysfunction by reducing endoplasmic reticulum stress and oxidative stress

Background

Long-term alcohol exposure is associated with oxidative stress, endoplasmic reticulum (ER) stress, and neuroinflammation, which may impair cognitive function. Probiotics supplements can significantly improve cognitive function in neurodegenerative diseases such as Alzheimer’s disease. Nevertheless, the effect of Lactobacillus plantarum ST-III culture supernatant (LP-cs) on alcohol-induced cognitive dysfunction remains unclear.

Methods

A mouse model of cognitive dysfunction was established by intraperitoneal injection of alcohol (2 g/kg body weight) for 28 days. Mice were pre-treated with LP-cs, and cognitive function was evaluated using the Morris water maze test. Hippocampal tissues were collected for biochemical and molecular analysis.

Results

LP-cs significantly ameliorated alcohol-induced decline in learning and memory function and hippocampal morphology changes, neuronal apoptosis, and synaptic dysfunction. A mechanistic study showed that alcohol activated protein kinase R-like endoplasmic reticulum kinase (PERK) signaling and suppressed brain derived neurotrophic factor (BDNF) levels via ER stress in the hippocampus, which LP-cs reversed. Alcohol activated oxidative stress and inflammation responses in the hippocampus, which LP-cs reversed.

Conclusion

LP-cs significantly ameliorated alcohol-induced cognitive dysfunction and cellular stress. LP-cs might serve as an effective treatment for alcohol-induced cognitive dysfunction.

The relationship between short-term PM2.5 exposure and outpatient visits for acne vulgaris in Chongqing, China: a time-series study

Many researches have reported the air pollution impacts, either long term or short term, on inflammatory skin diseases, but there are few studies on the relation between PM_2.5 and acne vulgaris. To determine the correlation between short-term PM_2.5 exposure and acne outpatient visits, data for 120,842 acne vulgaris outpatient visits between December 2013 and December 2019 were obtained from three large hospitals in Chongqing, China. Both single-pollutant models and two-pollutant models were established to explore the relationship between PM_2.5 exposure and acne outpatient visits. The stratified analyses were conducted through two-sample z-tests to investigate the possible gender (male or female) and age (< 25 years or ≥ 25 years) differences in PM_2.5 effects. The results demonstrated positive correlations between PM_2.5 concentrations and acne outpatient visits. A 10 μg/m³ increase in PM_2.5 concentration was associated with a 1.71% (95% CI: 1.06-2.36%) increase in acne outpatient visits at lag 0-7 day. Stratified analyses showed that PM_2.5 effects were greater in individuals aged ≥ 25 years than those aged < 25 years, but no gender difference was found. In conclusion, short-term PM_2.5 exposure was positively associated with the risk of acne outpatient visits, especially for people ≥ 25 years old.

Comorbidity of osteoporosis and Alzheimer's disease: Is `AKT `-ing on cellular glucose uptake the missing link?

Osteoporosis and Alzheimer's disease (AD) are both degenerative diseases. Osteoporosis often proceeds cognitive deficits, and multiple studies have revealed common triggers that lead to energy deficits in brain and bone. Risk factors for osteoporosis and AD, such as obesity, type 2 diabetes, aging, chemotherapy, vitamin deficiency, alcohol abuse, and apolipoprotein Eε4 and/or Il-6 gene variants, reduce cellular glucose uptake, and protective factors, such as estrogen, insulin, exercise, mammalian target of rapamycin inhibitors, hydrogen sulfide, and most phytochemicals, increase uptake. Glucose uptake is a fine-tuned process that depends on an abundance of glucose transporters (Gluts) on the cell surface. Gluts are stored in vesicles under the plasma membrane, and protective factors cause these vesicles to fuse with the membrane, resulting in presentation of Gluts on the cell surface. This translocation depends mainly on AKT kinase signaling and can be affected by a range of factors. Reduced AKT kinase signaling results in intracellular glucose deprivation, which causes endoplasmic reticulum stress and iron depletion, leading to activation of HIF-1α, the transcription factor necessary for higher Glut expression. The link between diseases and aging is a topic of growing interest. Here, we show that diseases that affect the same biochemical pathways tend to co-occur, which may explain why osteoporosis and/or diabetes are often associated with AD.

Transcriptional and Epigenetic Regulation of Monocyte and Macrophage Dysfunction by Chronic Alcohol Consumption

Drinking alcohol, even in moderation, can affect the immune system. Studies have shown disproportionate effects of alcohol on circulating and tissue-resident myeloid cells (granulocytes, monocytes, macrophages, dendritic cells). These cells orchestrate the body's first line of defense against microbial challenges as well as maintain tissue homeostasis and repair. Alcohol's effects on these cells are dependent on exposure pattern, with acute drinking dampening but chronic drinking enhancing production of inflammatory mediators. Although chronic drinking is associated with heightened systemic inflammation, studies on tissue resident macrophage populations in several organs including the spleen, liver, brain, and lung have also shown compromised functional and metabolic capacities of these cells. Many of these effects are thought to be mediated by oxidative stress caused by alcohol and its metabolites which can directly impact the cellular epigenetic landscapes. In addition, since myeloid cells are relatively short-lived in circulation and are under constant repopulation from the bone marrow compartment, alcohol's effects on bone marrow progenitors and hematopoiesis are important for understanding the impact of alcohol systemically on these myeloid populations. Alcohol-induced disruption of progenitor, circulating, and tissue resident myeloid populations contribute to the increased susceptibility of patients with alcohol use disorders to viral and bacterial infections. In this review, we provide an overview of the impact of chronic alcohol consumption on the function of monocytes and macrophages in host defense, tissue repair and inflammation. We then summarize our current understanding of the mechanisms underlying alcohol-induced disruption and examine changes in transcriptome and epigenome of monocytes and mcrophages. Overall, chronic alcohol consumption leads to hyper-inflammation concomitant with decreased microbial and wound healing responses by monocytes/macrophages due to a rewiring of the epigentic and transcriptional landscape. However, in advanced alcoholic liver disease, myeloid cells become immunosuppressed as a response to the surrounding hyper-inflammatory milieu. Therefore, the effect of chronic alcohol on the inflammatory response depends on disease state and the immune cell population.

The role of hypoxia-inducible factor 1-alpha in inflammatory bowel disease

Inflammatory bowel disease (IBD) develops as a result of a combination of genetic predisposition, dysbiosis of the gut microbiota, and environmental influences, which is mainly represented by ulcerative colitis (UC) and Crohn's disease (CD). IBDs can result in inflammatory hypoxia by causing intestinal inflammation and vascular damage. The hypoxia-inducible factor 1-alpha (HIF-1α), as a transcription factor, can regulate the cellular adaptation to low oxygen levels and support the development and function of the gut barrier. HIF-αplays its functions through translocating into the nucleus, dimerizing with HIF-1β, and binding to hypoxia-responsive elements of HIF-1 target genes. So far, most studies have addressed the function of HIF-1α in murine models of IBD. In this review, we aim to outline the major roles of HIF-1α in the IBD.

Selection pressure at altitude for genes related to alcohol metabolism: A role for endogenous enteric ethanol synthesis?

NEW FINDINGS

What is the topic of this review? Highland natives have undergone natural selection for genetic variants advantageous in adaptation to the hypobaric hypoxia experienced at high altitude. Why genes related to alcohol metabolism appear consistently selected for has not been greatly considered. We hypothesize that altitude-related changes in the gut microbiome offer one possible explanation. What advances does it highlight? Low intestinal oxygen tension might favour the production of ethanol through anaerobic fermentation by the gut microbiome. Subsequent increases in endogenous ethanol absorption could therefore provide a selection pressure for gene variants favouring its increased degradation, or perhaps reduced degradation if endogenously synthesized ethanol acts as a metabolic signalling molecule.

ABSTRACT

Reduced tissue availability of oxygen results from ascent to high altitude, where atmospheric pressure, and thus the partial pressure of inspired oxygen, fall (hypobaric hypoxia). In humans, adaptation to such hypoxia is necessary for survival. These functional changes remain incompletely characterized, although metabolic adaptation (rather than simple increases in convective oxygen delivery) appears to play a fundamental role. Those populations that have remained native to high altitude have undergone natural selection for genetic variants associated with advantageous phenotypic traits. Interestingly, a consistent genetic signal has implicated alcohol metabolism in the human adaptive response to hypobaric hypoxia. The reasons for this remain unclear. One possibility is that increased alcohol synthesis occurs through fermentation by gut bacteria in response to enteric hypoxia. There is growing evidence that anaerobes capable of producing ethanol become increasingly prevalent with high-altitude exposure. We hypothesize that: (1) ascent to high altitude renders the gut luminal environment increasingly hypoxic, favouring (2) an increase in the population of enteric fermenting anaerobes, hence (3) the synthesis of alcohol which, through systemic absorption, leads to (4) selection pressure on genes relating to alcohol metabolism. In theory, alcohol could be viewed as a toxic product, leading to selection of gene variants favouring its metabolism. On the contrary, alcohol is a metabolic substrate that might be beneficial. This mechanism could also account for some of the interindividual differences of lowlanders in acclimatization to altitude. Future research should be aimed at determining any shifts to favour ethanol-producing anaerobes after ascent to altitude.

Maintenance of gut barrier integrity after injury: Trust your gut microRNAs

The gastrointestinal (GI) tract is a highly dynamic structure essential for digestion, nutrient absorption, and providing an interface to prevent gut bacterial translocation. In order to maintain the barrier function, the gut utilizes many defense mechanisms including proliferation, apoptosis, and apical junctional complexes. Disruption of any of these parameters due to injury or disease could negatively impact the intestinal barrier function and homeostasis resulting in increased intestine inflammation, permeability, bacterial dysbiosis, and tissue damage. MicroRNAs are small noncoding RNA sequences that are master regulators of normal cellular homeostasis. These regulatory molecules affect cellular signaling pathways and potentially serve as candidates for providing a mechanism of impaired gut barrier integrity following GI-related pathologic conditions, ethanol exposure, or trauma such as burn injury. MicroRNAs influence cellular apoptosis, proliferation, apical junction complex expression, inflammation, and the microbiome. Due to their widespread functional affiliations, altered expression of microRNAs are associated with many pathologic conditions. This review explores the role of microRNAs in regulation of intestinal barrier integrity. The studies reviewed demonstrate that microRNAs largely impact intestine barrier function and provide insight behind the observed adverse effects following ethanol and burn injury. Furthermore, these studies suggest that microRNAs are excellent candidates for therapeutic intervention or for biomarkers to manage gut barrier integrity following trauma such as burn injury and other GI-related pathologic conditions.

Transcriptomic-based toxicological investigations of ethanol to human umbilical vein endothelial cells

Ethanol has a complex effect on the cardiovascular system in humans, but the systemic effects of ethanol to endothelial cells were rarely investigated. In this study, we exposed human umbilical vein endothelial cells (HUVECs) to 5- or 50-mM ethanol and performed transcriptomics to investigate the systemic effects of ethanol. While these concentrations of ethanol did not significantly affect HUVEC viability, 5-mM ethanol significantly upregulated and downregulated 59 and 73 genes, respectively, whereas 50-mM ethanol significantly upregulated and downregulated 50 and 80 genes, respectively. Totally, 37 genes were shared by the two concentrations of ethanol. The most significantly altered gene ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway after 5-mM ethanol treatment were nucleic acid binding (GO:0003676) and Herpes simplex virus 1 infection (ko05168), respectively, whereas the most significantly altered GO term and KEGG pathway by 50-mM ethanol treatment were aryl sulfotransferase activity (GO:0004062) and chemical carcinogenesis (ko05204). We further verified that ethanol treatment downregulated the mRNA levels of CD38 molecule (CD38), ORAI calcium release-activated calcium modulator 2 (ORAI2), cysteinyl leukotriene receptor 2 (CYSLTR2), key genes involved in calcium signaling pathway (ko04020), as well as integrin subunit alpha 2 (ITGA2), and cAMP responsive element binding protein 3 like 2 (CREB3L2), key genes involved in PI3K-Akt signaling pathway (ko04151). The results from this study suggested that ethanol could induce systemic effects and alter signaling pathways in HUVECs.

Protective effects of PX478 on gut barrier in a mouse model of ethanol and burn injury

Ethanol remains a confounder in postburn pathology, which is associated with an impaired intestinal barrier. Previously, we demonstrated that ethanol and burn injury reduce intestinal oxygen delivery (hypoxia) and alters microRNA (miR) expression in small intestinal epithelial cells. Hypoxia has been shown to influence expression of miRs and miR biogenesis components. Therefore, we examined whether hypoxia influences expression of miR biogenesis components (drosha, dicer, and argonaute-2 [ago-2]) and miRs (-7a and -150) and whether these changes impacted other parameters following ethanol and burn injury. Mice were gavaged with ethanol (∼2.9 g/kg) 4 h before receiving a ∼12.5% total body surface full thickness burn. Mice were resuscitated at the time of injury with normal saline with or without 5 mg/kg PX-478, a hypoxia-inducible factor-1α inhibitor. One day following injury mice were euthanized, and the expression of miRs and their biogenesis components as well as bacterial growth, tight junction proteins, intestinal transit, and permeability were assessed. Ethanol combined with burn injury significantly reduced expression of drosha, ago-2, miRs (-7a and -150), occludin, zonula occludens-1, claudin-4, zonula occludens-1, mucins-2 and -4, and intestinal transit compared to shams. Furthermore, there was an increase in intestinal permeability, total bacteria, and Enterobacteriaceae populations following the combined injury compared to shams. PX-478 treatment improved expression of drosha, ago-2, miRs (-7a and -150), occludin, claudin-4, zonula occludens-1, and mucin-2. PX-478 treatment also improved intestinal transit and reduced dysbiosis and permeability. These data suggest that PX-478 improves miR biogenesis and miR expression, and restores barrier integrity while reducing bacterial dysbiosis following ethanol and burn injury.

Parkin deficiency accentuates chronic alcohol intake-induced tissue injury and autophagy defects in brain, liver and skeletal muscle

Alcoholism leads to organ injury including mitochondrial defect and apoptosis with evidence favoring a role for autophagy dysregulation in alcoholic damage. Parkin represents an autosomal recessive inherited gene for Parkinson's disease and an important member of selective autophagy for mitochondria. The association between Parkinson's disease and alcoholic injury remains elusive. This study aimed to examine the effect of parkin deficiency on chronic alcohol intake-induced organ injury in brain, liver and skeletal muscle (rectus femoris muscle). Adult parkin-knockout (PRK-/-) and wild-type mice were placed on Liber-De Carli alcohol liquid diet (4%) for 12 weeks prior to assessment of liver enzymes, intraperitoneal glucose tolerance, protein carbonyl content, apoptosis, hematoxylin and eosin morphological staining, and mitochondrial respiration (cytochrome c oxidase, NADH:cytochrome c reductase and succinate:cytochrome c reductase). Autophagy protein markers were monitored by western blot analysis. Our data revealed that chronic alcohol intake imposed liver injury as evidenced by elevated aspartate aminotransferase and alanine transaminase, glucose intolerance, elevated protein carbonyl formation, apoptosis, focal inflammation, necrosis, microvesiculation, autophagy/mitophagy failure and dampened mitochondrial respiration (complex IV, complexes I and III, and complexes II and III) in the brain, liver and rectus femoris skeletal muscle. Although parkin ablation itself did not generate any notable effects on liver enzymes, insulin sensitivity, tissue carbonyl damage, apoptosis, tissue morphology, autophagy or mitochondrial respiration, it accentuated alcohol intake-induced tissue damage, apoptosis, morphological change, autophagy/mitophagy failure and mitochondrial injury without affecting insulin sensitivity. These data suggest that parkin plays an integral role in the preservation against alcohol-induced organ injury, apoptosis and mitochondrial damage.