Molecular targets in the treatment of alcoholic hepatitis

Schisandra chinensis polysaccharide prevents alcohol-associated liver disease in mice by modulating the gut microbiota-tryptophan metabolism-AHR pathway axis

Polysaccharides are one of the main active components of Schisandra chinensis and have been shown to possess diverse biological activities. In this study, we investigated the preventive effect of Schisandra chinensis polysaccharide (SCP) on alcohol-associated liver disease (ALD) by chronic-plus-binge ethanol feeding and the underlying mechanisms. The results suggest that supplementation with SCP prevents ALD by modulating gut microbiota and tryptophan (Trp) metabolism. SCP significantly enriched intestinal Lactobacillus, especially Lactobacillus reuteri, restored the content of intestinal indole derivatives (TRM, IAA, ILA, IALD) that can activate the aromatic hydrocarbon receptor (AHR), increased the colon AHR pathway activity, repaired intestinal barriers damage, reduced the circulating LPS, and inhibited the liver inflammation, oxidative stress, and lipid accumulation. The in vitro Trp metabolizing capacity was used to selected for a strain of L.reuteri whose in vitro proliferation was similarly promoted by SCP. Importantly, the gavage of the L.reuteri increased intestinal TRM content in mice. In addition, its ALD preventive effects were consistent with SCP and dependent on the colon AHR pathway. Our findings confirm that SCP may prevent ALD by mudulating the gut microbial-Trp metabolism-AHR pathway axis, suggesting that supplementation with the prebiotic SCP is an effective way to prevent ALD.

Interleukin-17 in Liver Disease Pathogenesis

Interleukin 17A (IL-17A)-producing T helper 17 (Th17) cells were identified as a subset of T helper cells that play a critical role in host defense against bacterial and fungal pathogens. Th17 cells differentiate from Th0 naïve T-cells in response to transforming growth factor β1 (TGF-β1) and IL-6, the cytokines which also drive development of liver fibrosis, require activation of transcription factor retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt). IL-17A signals through the ubiquitously expressed receptor IL-17RA. Expression of IL-17RA is upregulated in patients with hepatitis B virus/hepatitis C virus (HBV/HCV) infections, nonalcoholic steatohepatitis (NASH), alcohol-associated liver disease (AALD), hepatocellular carcinoma (HCC), and experimental models of chronic toxic liver injury. The role of IL-17 signaling in the pathogenesis of NASH- and AALD-induced metabolic liver injury and HCC will be the focus of this review. The role of IL-17A-IL-17RA axis in mediation of the cross-talk between metabolically injured hepatic macrophages, hepatocytes, and fibrogenic myofibroblasts will be discussed.

The implementation of drug reposition for alcoholic hepatitis based on a sub-pathway integration strategy

Background

Alcoholic hepatitis (AH) is one of the most severe forms of liver disease. The therapies which are currently available are not entirely effective, and thus novel therapies are urgently needed. However, the development of these novel therapies is limited due to incomplete information about the molecular mechanisms involved in AH.

Methods

The microarray data (GSE28619) was downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between the AH and the control samples were identified using the significant analysis of microarrays (SAM) method. Metabolic sub-pathways were identified using the SubpathwayMiner R package. Cell Counting Kit-8 (CCK-8) was used to evaluate the cell viability of AML-12 cells treated with different concentrations of ethanol or riboflavin. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were employed to show the hepatocyte function.

Results

A total of 1,041 genes were determined to be expressed differentially. We then identified 11 metabolic sub-pathways that could be involved in the development of AH. This was followed by a final integrated analysis of the sub-pathways involved in AH as well as the sub-pathways involved in the drug-affected cases. The final integration results led to the identification of 64 small molecular drugs. A potential novel drug (riboflavin) involved in the fatty acid metabolism pathway was identified for further investigation. Riboflavin at the 60 nM for 24 h could reverse ethanol-induced AML-12 cell injury and could markedly decrease ALT and AST activity. The decrease in the activities of these two enzymes was observed in a dose-dependent manner when it was compared to ethanol alone, which suggests that riboflavin has a protective effect against liver cell injury caused by alcoholism.

Conclusions

To summarize, the candidate agents which are identified in the present study might give practitioners insight into the development of novel therapeutic approaches for AH.

Dihydromyricetin Protects the Liver via Changes in Lipid Metabolism and Enhanced Ethanol Metabolism

Background

Excess alcohol (ethanol, EtOH) consumption is a significant cause of chronic liver disease, accounting for nearly half of the cirrhosis‐associated deaths in the United States. EtOH‐induced liver toxicity is linked to EtOH metabolism and its associated increase in proinflammatory cytokines, oxidative stress, and the subsequent activation of Kupffer cells. Dihydromyricetin (DHM), a bioflavonoid isolated from Hovenia dulcis, can reduce EtOH intoxication and potentially protect against chemical‐induced liver injuries. But there remains a paucity of information regarding the effects of DHM on EtOH metabolism and liver protection. As such, the current study tests the hypothesis that DHM supplementation enhances EtOH metabolism and reduces EtOH‐mediated lipid dysregulation, thus promoting hepatocellular health.

Methods

The hepatoprotective effect of DHM (5 and 10 mg/kg; intraperitoneal injection) was evaluated using male C57BL/6J mice and a forced drinking ad libitum EtOH feeding model and HepG2/VL‐17A hepatoblastoma cell models. EtOH‐mediated lipid accumulation and DHM effects against lipid deposits were determined via H&E stains, triglyceride measurements, and intracellular lipid dyes. Protein expression of phosphorylated/total proteins and serum and hepatic cytokines was determined via Western blot and protein array. Total NAD⁺/NADH Assay of liver homogenates was used to detect NAD + levels.

Results

DHM reduced liver steatosis, liver triglycerides, and liver injury markers in mice chronically fed EtOH. DHM treatment resulted in increased activation of AMPK and downstream targets, carnitine palmitoyltransferase (CPT)‐1a, and acetyl CoA carboxylase (ACC)‐1. DHM induced expression of EtOH‐metabolizing enzymes and reduced EtOH and acetaldehyde concentrations, effects that may be partly explained by changes in NAD⁺. Furthermore, DHM reduced the expression of proinflammatory cytokines and chemokines in sera and cell models.

Conclusion

In total, these findings support the utility of DHM as a dietary supplement to reduce EtOH‐induced liver injury via changes in lipid metabolism, enhancement of EtOH metabolism, and suppressing inflammation responses to promote liver health.

Semen hoveniae extract ameliorates alcohol-induced chronic liver damage in rats via modulation of the abnormalities of gut-liver axis

BACKGROUND

Hovenia dulcis Thunb. is considered as a traditional herbal medicine that has been used in the treatment for ethanol-induced liver disease for centuries. Recently, substantial studies demonstrated that Semen hoveniae extract (SHE) not only suppressed the hepatic steatosis caused by chronic ethanol exposure, but also inhibited lipopolysaccharide-stimulated inflammatory responses. Nevertheless, the underlying molecular mechanisms largely remained elusive.

AIM

To determine the hepatoprotective effects of SHE on ethanol-triggered liver damage and further elucidate its potential mechanisms.

METHODS

In the present study, the Sprague-Dawley rats were fed with the Lieber-DeCarli diet containing alcohol or isocaloric maltose dextrin as control diet with or without SHE (300 and 600 mg/kg/d bw) for 8 weeks. The levels of serum biomarkers (ALT, AST and LDH) and LPS were detected by biochemical assay kits and endotoxin detection LAL kit, respectively. The histopathological changes of liver and intestinal tissues were observed by hematoxylin and eosin (H&E) staining and Transmission electron microscope (TEM). The expressions of CD14, TLR4, MyD88, NF-κB, Iκ-B, P-Iκ-B and TNF-α in liver, and ZO-1 and occludin in intestine were determined by western blot. The faecal microbial composition was determined by16S rRNA Gene Sequencing Analysis.

RESULTS

Biochemical and histopathological analysis revealed that SHE significantly alleviated the lipid deposition and inflammation response in liver induced by ethanol. SHE remarkably inhibited the TLR4 pathway and its downstream inflammatory mediators, and up-regulated the expressions of ZO-1 and occludin in the intestine. The further investigations suggested SHE dramatically reversed ethanol-induced alterations in the intestinal microbial flora and decreased the generation of gut-derived endotoxin.

CONCLUSION

In summary, SHE probably modulated abnormalities of gut-liver axis and inhibited TLR4-associated inflammatory mediators activation to exert its hepatoprotective properties. These findings suggested that SHE as a traditional therapeutic options which may play an essential role in protecting against the chronic ethanol-triggered liver injury.

Lactobacillus plantarum LC27 and Bifidobacterium longum LC67 mitigate alcoholic steatosis in mice by inhibiting LPS-mediated NF-κB activation through restoration of the disturbed gut microbiota

Long-term exposure to ethanol simultaneously causes gastrointestinal inflammation, liver injury, and steatosis. In the present study, we investigated the effects of Bifidobacterium longum LC67, Lactobacillus plantarum LC27, and their mixture (LM) against ethanol-induced steatosis in mice. Exposure to ethanol caused liver damage: it increased ALT, AST, TG, TC, and lipopolysaccharide levels in the blood and induced NF-κB activation in the liver. Oral administration of LC27, LC67, or LM in mice reduced ethanol-induced ALT, AST, TG, and TC levels in the blood and liver. These also suppressed ethanol-induced NF-κB activation and α-smooth muscle actin expression in the liver and increased ethanol-suppressed AMPK activation. Treatment with LC27, LC67, or LM increased ethanol-suppressed alcohol dehydrogenase and acetaldehyde dehydrogenase activities in the liver, as well as tight junction protein expression in the liver and colon. Moreover, treatment with LC27, LC67, or LM restored the ethanol-disturbed gut microbiota composition, such as the increased population of Proteobacteria, and inhibited fecal and blood lipopolysaccharide levels. These inhibited NF-κB activation and increased tight junction protein expression in ethanol- or lipopolysaccharide-stimulated Caco-2 cells. These findings suggest that LC27, LC67, and LM can alleviate alcoholic steatosis by inhibiting LPS-mediated NF-κB activation through restoration of the disturbed gut microbiota.

Baseline urine metabolic phenotype in patients with severe alcoholic hepatitis and its association with outcome

Severe alcoholic hepatitis (SAH) has a high mortality rate, and corticosteroid therapy is effective in 60% patients. This study aimed to investigate a baseline metabolic phenotype that could help stratify patients not likely to respond to steroid therapy and to have an unfavorable outcome. Baseline urine metabolome was studied in patients with SAH using ultra‐high performance liquid chromatography and high‐resolution mass spectrometry. Patients were categorized as responders (Rs, n = 52) and nonresponders (NRs, n = 8) at day 7 according to the Lille score. Multivariate projection analysis identified metabolites in the discovery cohort (n = 60) and assessed these in a validation cohort of 80 patients (60 Rs, 20 NRs). A total of 212 features were annotated by using metabolomic/biochemical/spectral databases for metabolite identification. After a stringent selection procedure, a total of nine urinary metabolites linked to mitochondrial functions significantly discriminated nonresponders, most importantly by increased acetyl‐L‐carnitine (12‐fold), octanoylcarnitine (4‐fold), decanoylcarnitine (4‐fold), and alpha‐ketoglutaric acid (2‐fold) levels. Additionally, urinary acetyl‐L‐carnitine and 3‐hydroxysebasic acid discriminated nonsurvivors (P < 0.01). These urinary metabolites significantly correlated to severity indices and mortality (r > 0.3; P < 0.01) and were associated with nonresponse (odds ratio >3.0; P < 0.001). In the validation cohort, baseline urinary acetyl‐L‐carnitine documented an area under the receiver operating curve of 0.96 (0.85‐0.99) for nonresponse prediction and a hazard ratio of 3.5 (1.5‐8.3) for the prediction of mortality in patients with SAH. Acetyl‐L‐carnitine at a level of >2,500 ng/mL reliably segregated survivors from nonsurvivors (P < 0.01, log‐rank test) in our study cohort. Conclusion: Urinary metabolome signatures related to mitochondrial functions can predict pretherapy steroid response and disease outcome in patients with SAH. (Hepatology Communications 2018;2:628‐643)

Dihydromyricetin modulates p62 and autophagy crosstalk with the Keap-1/Nrf2 pathway to alleviate ethanol-induced hepatic injury

Increasing evidence has demonstrated that dihydromyricetin (DMY) contains highly effective antioxidative, anti-inflammatory, anti-microbial and anti-diabetic properties. Nevertheless, the underlying hepatoprotective mechanisms of DMY have infrequently been reported thus far. In the present study, C57BL/6 mice were fed with the Lieber-DeCarli diet containing alcohol or isocaloric maltose dextrin as a control diet with or without DMY (75 and 150mg/kg/d bw) for 6 weeks. DMY significantly attenuated hepatic enzyme release, hepatic lipid peroxidation and triglyceride deposition induced by chronic alcohol exposure. In addition, DMY dramatically attenuated the alcohol-triggered elevation of the level of inflammatory cytokines and partially recovered hepatic pathological changes. Notably, DMY remarkably modified aberrant expression of CYP2E1, Keap-1 and HO-1 in the liver and simultaneously ameliorated disordered nuclear localization of NF-κB and Nrf2 to exert its hepatoprotective effects. Further mechanistic exploration suggested that DMY activated Nrf2, possibly mediated through the autophagy pathway. Analysis of the crosstalk among p62, Keap-1 and Nrf2 demonstrated that the p62 upregulation caused by DMY contributes to a positive feedback loop in Nrf2 activation. In summary, DMY likely modulates p62 and autophagy crosstalk with the Keap-1/Nrf2 pathway to alleviate liver steatosis and the inflammatory response in the pathological progression of ALD.

New treatment options for alcoholic hepatitis

The burden of alcoholic liver disease has rapidly grown in the past two decades and is expected to increase further in the coming years. Alcoholic hepatitis, the most florid presentation of alcoholic liver disease, continues to have high morbidity and mortality, with significant financial and healthcare burden with limited treatment options. Steroids remain the current standard of care in severe alcoholic hepatitis in carefully selected patients. No specific treatments are available for those patients who are steroid ineligible, intolerant or unresponsive. Liver transplant has shown good short-term outcome; however, feasibility, ethical and economic concerns remain. Modification of gut microbiota composition and their products, such as lipopolysaccharide, nutritional interventions, immune modulation, increasing steroid sensitivity, genetic polymorphism and epigenetic modification of alcohol induced liver damage, augmenting hepatic regeneration using GCSF are potential therapeutic avenues in steroid non-responsive/ineligible patients. With better understanding of the pathophysiology, using “Omics” platforms, newer options for patients with alcoholic hepatitis are expected soon.

Alcoholic Liver Disease: Role of Cytokines

The present review spans a broad spectrum of topics dealing with alcoholic liver disease (ALD), including clinical and translational research. It focuses on the role of the immune system and the signaling pathways of cytokines in the pathogenesis of ALD. An additional factor that contributes to the pathogenesis of ALD is lipopolysaccharide (LPS), which plays a central role in the induction of steatosis, inflammation, and fibrosis in the liver. LPS derived from the intestinal microbiota enters the portal circulation, and is recognized by macrophages (Kupffer cells) and hepatocytes. In individuals with ALD, excessive levels of LPS in the liver affect immune, parenchymal, and non-immune cells, which in turn release various inflammatory cytokines and recruit neutrophils and other inflammatory cells. In this review, we elucidate the mechanisms by which alcohol contributes to the activation of Kupffer cells and the inflammatory cascade. The role of the stellate cells in fibrogenesis is also discussed.

Ethanol and liver: Recent insights into the mechanisms of ethanol-induced fatty liver

Alcoholic fatty liver disease (AFLD), a potentially pathologic condition, can progress to steatohepatitis, fibrosis, and cirrhosis, leading to an increased probability of hepatic failure and death. Alcohol induces fatty liver by increasing the ratio of reduced form of nicotinamide adenine dinucleotide to oxidized form of nicotinamide adenine dinucleotide in hepatocytes; increasing hepatic sterol regulatory element-binding protein (SREBP)-1, plasminogen activator inhibitor (PAI)-1, and early growth response-1 activity; and decreasing hepatic peroxisome proliferator-activated receptor-α activity. Alcohol activates the innate immune system and induces an imbalance of the immune response, which is followed by activated Kupffer cell-derived tumor necrosis factor (TNF)-α overproduction, which is in turn responsible for the changes in the hepatic SREBP-1 and PAI-1 activity. Alcohol abuse promotes the migration of bone marrow-derived cells (BMDCs) to the liver and then reprograms TNF-α expression from BMDCs. Chronic alcohol intake triggers the sympathetic hyperactivity-activated hepatic stellate cell (HSC) feedback loop that in turn activates the HSCs, resulting in HSC-derived TNF-α overproduction. Carvedilol may block this feedback loop by suppressing sympathetic activity, which attenuates the progression of AFLD. Clinical studies evaluating combination therapy of carvedilol with a TNF-α inhibitor to treat patients with AFLD are warranted to prevent the development of alcoholic liver disease.

New advances in molecular mechanisms and emerging therapeutic targets in alcoholic liver diseases

Alcoholic liver disease is a major health problem in the United States and worldwide. Chronic alcohol consumption can cause steatosis, inflammation, fibrosis, cirrhosis and even liver cancer. Significant progress has been made to understand key events and molecular players for the onset and progression of alcoholic liver disease from both experimental and clinical alcohol studies. No successful treatments are currently available for treating alcoholic liver disease; therefore, development of novel pathophysiological-targeted therapies is urgently needed. This review summarizes the recent progress on animal models used to study alcoholic liver disease and the detrimental factors that contribute to alcoholic liver disease pathogenesis including miRNAs, S-adenosylmethionine, Zinc deficiency, cytosolic lipin-1β, IRF3-mediated apoptosis, RIP3-mediated necrosis and hepcidin. In addition, we summarize emerging adaptive protective effects induced by alcohol to attenuate alcohol-induced liver pathogenesis including FoxO3, IL-22, autophagy and nuclear lipin-1α.

New Approaches for Studying Alcoholic Liver Disease

Alcoholic liver disease (ALD) is major cause of chronic liver injury which results in liver fibrosis and cirrhosis. According to the surveillance report published by the National Institute on Alcohol Abuse and Alcoholism, liver cirrhosis is the 12th leading cause of death in the United States with 48 % of these deaths being attributed to excessive alcohol consumption. ALD includes a spectrum of disorders from simple steatosis to steatohepatitis, fibrosis, and hepatocellular carcinoma. Several mechanisms play a critical role in the pathogenesis of ALD. These include ethanol-induced oxidative stress and depletion of glutathione, pathological methionine metabolism, increased gut permeability and release of endotoxins into the portal blood, recruitment and activation of inflammatory cells including bone marrow-derived and liver resident macrophages (Kupffer cells). Chronic alcohol consumption results in liver damage and activation of hepatic stellate cells (HSCs) and myofibroblasts, leading to liver fibrosis. Here we discuss the current view on factors that are specific for different stages of ALD and those that regulate its progression, including cytokines and chemokines, alcohol-responsive intracellular signaling pathways, and transcriptional factors. We also review recent studies demonstrating that alcohol-mediated changes can be regulated on an epigenetic level, including microRNAs. Finally, we discuss the reversibility of liver fibrosis and inactivation of HSCs as a potential strategy for treating alcohol-induced liver damage.

Focus on alcoholic liver disease: from nosography to treatment

Abusive alcohol intake currently ranks as a major cause of liver disease, and is associated with significant mortality worldwide. Alcoholic liver disease (ALD) generically defines liver abnormalities ranging from liver steatosis to the end-stages of disease such as liver cirrhosis. Information regarding the precise incidence and prevalence of ALD is still limited by a lack of large population-based studies and by the absence of large systematic reviews of all epidemiological data available. However, existing collected data show an overall increase in the number of alcohol abusers and alcohol-related liver disease. The burden exerted on medical systems worldwide is significant, with hospitalization and management costs rising constantly over the years. A great number of all cirrhosis-related deaths in Europe and a significant percentage worldwide are associated with alcohol consumption. The main possible risk factors for ALD are the amount and duration of alcohol abuse, patterns of drinking and the type of alcoholic beverage consumed. However, ALD does not progress to cirrhosis in all patients, therefore a series of additional factors are implicated. Even though insufficiently studied, genetic factors are generally regarded as highly important, and the presence of comorbidities and dietary habits seem to play a role in disease onset and progression. This lack of clear pathophysiological data further translates in the absence of definite treatment for ALD and shall prove challenging in the coming years. In this article, we aimed to briefly review epidemiologic data on the burden of ALD, risk factors, clinical and nosographic as well as therapeutic aspects of this disease. Without attempting to be exhaustive, this short topic highlight emphasizes each point and may serve as a general guidance tool in the complicated literature related to ALD.

Pentoxifylline attenuates nitrogen mustard-induced acute lung injury, oxidative stress and inflammation

Nitrogen mustard (NM) is a toxic alkylating agent that causes damage to the respiratory tract. Evidence suggests that macrophages and inflammatory mediators including tumor necrosis factor (TNF)α contribute to pulmonary injury. Pentoxifylline is a TNFα inhibitor known to suppress inflammation. In these studies, we analyzed the ability of pentoxifylline to mitigate NM-induced lung injury and inflammation. Exposure of male Wistar rats (150-174 g; 8-10 weeks) to NM (0.125 mg/kg, i.t.) resulted in severe histopathological changes in the lung within 3d of exposure, along with increases in bronchoalveolar lavage (BAL) cell number and protein, indicating inflammation and alveolar-epithelial barrier dysfunction. This was associated with increases in oxidative stress proteins including lipocalin (Lcn)2 and heme oxygenase (HO)-1 in the lung, along with pro-inflammatory/cytotoxic (COX-2(+) and MMP-9(+)), and anti-inflammatory/wound repair (CD163+ and Gal-3(+)) macrophages. Treatment of rats with pentoxifylline (46.7 mg/kg, i.p.) daily for 3d beginning 15 min after NM significantly reduced NM-induced lung injury, inflammation, and oxidative stress, as measured histologically and by decreases in BAL cell and protein content, and levels of HO-1 and Lcn2. Macrophages expressing COX-2 and MMP-9 also decreased after pentoxifylline, while CD163+ and Gal-3(+) macrophages increased. This was correlated with persistent upregulation of markers of wound repair including pro-surfactant protein-C and proliferating nuclear cell antigen by Type II cells. NM-induced lung injury and inflammation were associated with alterations in the elastic properties of the lung, however these were largely unaltered by pentoxifylline. These data suggest that pentoxifylline may be useful in treating acute lung injury, inflammation and oxidative stress induced by vesicants.

Diagnosis and treatment of alcoholic hepatitis

Alcoholic liver disease (ALD) is increasing in incidence in the UK. It is the commonest cause of liver-related deaths, predominantly in people below the age of 60. Alcoholic hepatitis (AH) is an acute form of ALD with high mortality when severe. Jaundice and coagulopathy are clinical hallmarks of severe AH. Histology findings are characterised by parenchymal inflammation and hepatocellular damage although biopsy is only required when diagnostic uncertainty exists; clinical findings are usually sufficient for accurate diagnosis. Patients with AH should be stratified as non-severe or severe using non-invasive scoring systems such as the discriminant function or the Glasgow Alcoholic Hepatitis Score. In patients with non-severe AH, abstinence is the mainstay of treatment, and it is important that steps are taken to help patients stop drinking. Severe AH requires specialist treatment. Consensus guidelines recommend the use of prednisolone although this remains subject to clinical trials. Pentoxifylline may have a survival benefit if corticosteroids are contraindicated. Nutritional support and N-acetylcysteine should be considered for use in conjunction with corticosteroids although evidence of benefit is not conclusive. Patients with severe disease who do not respond to therapy within a week have a very poor outcome. Recent data have shown a survival benefit of liver transplantation in this group although this remains experimental at present. Current and future research should focus on targeted therapies for severe AH and those who fail first-line treatment.

Chronic ethanol consumption modulates growth factor release, mucosal cytokine production, and microRNA expression in nonhuman primates

BACKGROUND

Chronic alcohol consumption has been associated with enhanced susceptibility to both systemic and mucosal infections. However, the exact mechanisms underlying this enhanced susceptibility remain incompletely understood.

METHODS

Using a nonhuman primate model of ethanol (EtOH) self-administration, we examined the impact of chronic alcohol exposure on immune homeostasis, cytokine, and growth factor production in peripheral blood, lung, and intestinal mucosa following 12 months of chronic EtOH exposure.

RESULTS

EtOH exposure inhibited activation-induced production of growth factors hepatocyte growth factor (HGF), granulocyte colony-stimulating factor (G-CSF), and vascular-endothelial growth factor (VEGF) by peripheral blood mononuclear cells (PBMC). Moreover, EtOH significantly reduced the frequency of colonic Th1 and Th17 cells in a dose-dependent manner. In contrast, we did not observe differences in lymphocyte frequency or soluble factor production in the lung of EtOH-consuming animals. To uncover mechanisms underlying reduced growth factor and Th1/Th17 cytokine production, we compared expression levels of microRNAs in PBMC and intestinal mucosa. Our analysis revealed EtOH-dependent up-regulation of distinct microRNAs in affected tissues (miR-181a and miR-221 in PBMC; miR-155 in colon). Moreover, we were able to detect reduced expression of the transcription factors STAT3 and ARNT, which regulate expression of VEGF, G-CSF, and HGF and contain targets for these microRNAs. To confirm and extend these observations, PBMC were transfected with either mimics or antagomirs of miR-181 and miR-221, and protein levels of the transcription factors and growth factors were determined. Transfection of microRNA mimics led to a reduction in both STAT3/ARNT as well as VEGF/HGF/G-CSF levels. The opposite outcome was observed when microRNA antagomirs were transfected.

CONCLUSIONS

Chronic EtOH consumption significantly disrupts both peripheral and mucosal immune homeostasis, and this dysregulation may be mediated by changes in microRNA expression.