Alcoholic Hepatitis

Integrating behavioral interventions into a holistic approach to metabolic dysfunction-associated steatotic liver disease

INTRODUCTION

The therapeutic landscape of Metabolic dysfunction-Associated Steatotic Liver Disease (MASLD) is rapidly evolving with the FDA approval of resmetirom, the first authorized molecule to treat metabolic dysfunction-associated steatohepatitis. Clinical trials are investigating other promising molecules. However, this focus on pharmacotherapy may overshadow lifestyle interventions, which remain the cornerstone of MASLD management. A significant percentage of patients with MASLD struggle with an underlying eating disorder, often a precursor to obesity. The obesity pandemic, exacerbated by the increasing prevalence of binge eating, underscores the need for a psychological approach to address their common roots.

AREAS COVERED

We reviewed the current evidence on behavioral interventions for MASLD. Interventions such as self-monitoring, goal setting, and frequent counseling, have proven effective in achieving at least 5% weight loss. Cognitive behavioral therapy is the first-line treatment for eating disorders and has shown efficacy in treating binge eating and obesity. Further research is needed to establish the optimal behavioral therapy for MASLD, focusing on enhancing compliance and achieving sustained weight loss through diet and physical exercise.

EXPERT OPINION

The treatment of MASLD should not rely solely on pharmacotherapy targeting a single-organ manifestation. Instead, we must consider behavioral interventions, emphasizing the pivotal role of a holistic approach to this multifaceted disorder. [Figure: see text].

In Vivo Acute on Chronic Ethanol Effects in Liver: A Mouse Model Exhibiting Exacerbated Injury, Altered Metabolic and Epigenetic Responses

Chronic alcoholics who also binge drink (i.e., acute on chronic) are prone to an exacerbated liver injury but its mechanism is not understood. We therefore investigated the in vivo effects of chronic and binge ethanol ingestion and compared to chronic ethanol followed by three repeat binge ethanol on the liver of male C57/BL6 mice fed ethanol in liquid diet (4%) for four weeks followed by binge ethanol (intragastric administration, 3.5 g/kg body weight, three doses, 12h apart). Chronic followed by binge ethanol exacerbated fat accumulation, necrosis, decrease in hepatic SAM and SAM:SAH ratio, increase in adenosine levels, and elevated CYP2E1 levels. Histone H3 lysine acetylation (H3AcK9), dually modified phosphoacetylated histone H3 (H3AcK9/PS10), and phosphorylated H2AX increased after binge whereas phosphorylation of histone H3 ser 10 (H3S10) and H3 ser 28 (H3S28) increased after chronic ethanol-binge. Histone H3 lysine 4 and 9 dimethylation increased with a marked dimethylation in H3K9 in chronic ethanol binge group. Trimethylated histone H3 levels did not change. Nuclear levels of histone acetyl transferase GCN5 and histone deacetylase HDAC3 were elevated whereas phospho-CREB decreased in a distinctive manner. Taken together, acute on chronic ethanol ingestion caused amplification of liver injury and elicited characteristic profiles of histone modifications, metabolic alterations, and changes in nuclear protein levels. These findings demonstrate that chronic ethanol exposure renders liver more susceptible to repeat acute/binge ethanol induced acceleration of alcoholic liver disease.

Epigenetic histone modifications in a clinically relevant rat model of chronic ethanol-binge-mediated liver injury

PURPOSE

Ethanol binge augments liver injury after chronic ethanol consumption in humans, but the mechanism behind the enhanced liver injury by ethanol binge is not known. In this study we used a clinically relevant rat model in which liver injury is amplified by binge after chronic ethanol treatment and investigated the importance of histone modifications.

METHODS

Eight-week-old Sprague-Dawley rats were fed ethanol in a liquid diet for 4 weeks. Control rats were fed an isocaloric liquid diet. This was followed by three binge administrations of ethanol (intragastric 5 g/kg body weight, 12 h apart). In the control, ethanol was replaced by water. Four hours after the last binge administration, liver samples were analyzed for histone modifications and parameters of liver injury.

RESULTS

Chronic ethanol administration alone caused an increase in histone H3 ser10 and ser28 (H3S10 or S28) phosphorylation, and binge ethanol reduced their levels. Levels of dually modified phosphoacetylated histone H3 (H3AcK9/PS10) increased after acute binge ethanol and remained same after chronic ethanol binge. In contrast, histone H3 lysine-9 acetylation (H3AcK9) was not increased after chronic ethanol but increased significantly after acute binge and chronic ethanol binge. Increase in histone acetylation was accompanied by increased phospho-ERK1/2 in the nuclear extracts. Increased acetylation after chronic ethanol binge was also accompanied by increased protein levels of GCN5 histone acetyl transferase and a modest increase in HDAC3 in the nucleus. Histone lysine-9 dimethylation was significantly increased after chronic ethanol binge. Chronic ethanol binge also resulted in a decrease in the SAM:SAH ratio with a relative decrease of SAM levels and a corresponding increase in SAH levels.

CONCLUSIONS

Ethanol binge after chronic ethanol altered the profile of site-specific histone modifications and may underlie the mechanism of augmented liver injury by chronic-ethanol-binge-treated rats.

Role of oxidative stress in the pathogenesis of alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease, which represents a major cause of morbidity and mortality worldwide. The pathological process of alcohol-induced liver disease is characterized by a broad spectrum of morphological changes ranging from steatosis with minimal injury to more advanced liver damage, including steato-hepatitis and fibrosis/cirrhosis. Experimental and clinical studies increasingly show that the oxidative damage induced by ethanol contribute in many ways to the pathogenesis of alcohol hepatotoxicity. This article describes the contribution of oxidative mechanisms to liver damage by alcohol.

Binge ethanol and liver: new molecular developments

Binge consumption of alcohol is an alarming global health problem. Binge (acute) ethanol (EtOH) is implicated in the pathophysiology of alcoholic liver disease (ALD). New studies from experimental animals and from humans indicate that binge EtOH has profound effects on immunological, signaling, and epigenetic parameters of the liver. This is in addition to the known metabolic effects of acute EtOH. Binge EtOH alters the levels of several cellular components and dramatically amplifies liver injury in chronically EtOH exposed liver. These studies highlight the importance of molecular investigations into binge effects of EtOH for a better understanding of ALD and also to develop therapeutic strategies to control it. This review summarizes these recent developments.

A proteomic analysis of liver after ethanol binge in chronically ethanol treated rats

Background

Binge ethanol in rats after chronic ethanol exposure augments necrosis and steatosis in the liver. In this study, two-dimensional gel electrophoresis proteomic profiles of liver of control, chronic ethanol, control-binge, and chronic ethanol- binge were compared.

Results

The proteomic analysis identified changes in protein abundance among the groups. The levels of carbonic anhydrase 3 (CA3) were decreased after chronic ethanol and decreased further after chronic ethanol-binge. Ethanol binge alone in control rats had no effect on this protein suggesting its possible role in increased susceptibility to injury by binge after chonic ethanol treatment. A protein spot, in which both cytosolic isocitrate dehydrogenase (IDH1) and glutamine synthetase (GS) were identified, showed a small decrease after chronic ethanol binge but western blot demonstrated significant decrease only for glutamine synthetase in chronic ethanol treated rats. The level of gluathione S-transferase mu isoform (GSTM1) increased after chronic ethanol but was lower after chronic ethanol-binge compared to chronic ethanol treatment. The protein levels of the basic form of protein disulfide isomerase associated protein 3 (PDIA3) were significantly decreased and the acidic forms were increased after chronic ethanol- binge but not in chronic ethanol treated rats or ethanol binge in control rats. The significant changes in proteome profile in chronic ethanol binge were accompanied by a marked increase in liver injury as evidenced by enhanced steatosis, necrosis, increased 4-hydroxynonenal labeled proteins, CYP2E1 expression, and decreased histone H2AX phosphorylation.

Conclusions

Given the role of CA3, IDH1 and GST in oxidative stress; PDIA3 in protein quality control, apoptosis and DNA repair and decreased glutamine synthetase as a sensitive marker of pericentral liver injury this proteome study of chronic ethanol-binge rat model identifies these proteins for the first time as molecular targets with potential role in progression of liver injury by binge ethanol drinking.

Dysregulated phosphorylation and nuclear translocation of cyclic AMP response element binding protein (CREB) in rat liver after chronic ethanol binge

Binge ethanol during chronic ethanol abuse augments liver injury but the underlying mechanism remains unknown. CREB (cyclic AMP response element binding protein) is implicated as a key transcription factor in liver regeneration and hepatic glucose and lipid metabolism. We examined the effects of ethanol on the phosphorylation of CREB in hepatocytes, and in vivo in rat liver after chronic ethanol binge. For in vivo studies, rats were fed ethanol in liquid diet for 4 weeks followed by single binge administration of ethanol (intragastric, 5 g/kg body weight). Four hours after binge administration, liver samples were collected and analyzed. Treatment of hepatocytes with ethanol caused increased phosphorylation of p38 MAPK (mitogen activated protein kinase), MSK-1 (mitogen and stress activated kinase) and CREB in the nuclear compartment without activation of ERK1/2 (extracellular regulated kinase); whereas angiotensin II induced activation of CREB was accompanied by activation of ERK1/2. In chronic ethanol-binge studies, analysis of the whole cell extracts showed increased phosphorylation of CREB, with no effect on CREB protein levels; increased phospho-ERK1/2, and decreased phospho-p38 MAPK. In contrast, the nuclear levels of phospho-CREB and CREB protein were reduced. Reduction in phospho-CREB and CREB proteins in the nuclear extracts was accompanied by suppression of mRNA levels for CPT-1 (carnitine palmitoyl transferase-1) and increase in hepatic steatosis after binge. It is concluded that binge ethanol causes defect in the nuclear accumulation of CREB protein, phospho-CREB, and an exaggerated hepatic steatosis. These in vivo effects are distinct from the effects of ethanol on hepatocytes in vitro.

Elevated activation of ERK1 and ERK2 accompany enhanced liver injury following alcohol binge in chronically ethanol-fed rats

BACKGROUND

Binge drinking after chronic ethanol consumption is one of the important factors contributing to the progression of steatosis to steatohepatitis. The molecular mechanisms of this effect remain poorly understood. We have therefore examined in rats the effect of single and repeat ethanol binge superimposed on chronic ethanol intake on liver injury, activation of mitogen-activated protein kinases (MAPKs), and gene expression.

METHODS

Rats were chronically treated with ethanol in liquid diet for 4 weeks followed by single ethanol binge (5 gm/kg body weight) or 3 similar repeated doses of ethanol. Serum alcohol and alanine amino transferase (ALT) levels were determined by enzymatic methods. Steatosis was assessed by histology and hepatic triglycerides. Activation of MAPK, 90S ribosomal kinase (RSK), and caspase 3 were evaluated by Western blot. Levels of mRNA for tumor necrosis factor alpha (TNFα), early growth response-1 (egr-1), and plasminogen activator inhibitor-1 (PAI-1) were measured by real-time qRT-PCR.

RESULTS

Chronic ethanol treatment resulted in mild steatosis and necrosis, whereas chronic ethanol followed by binge group exhibited marked steatosis and significant increase in necrosis. Chronic binge group also showed significant increase (compared with chronic ethanol alone) in the phosphorylation of extracellular regulated kinase 1 (ERK1), ERK2, and RSK. Phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK did not increase by the binge. Ethanol binge, after chronic ethanol intake, caused increase in mRNA for egr-1 and PAI-1, but not TNFα.

CONCLUSIONS

Chronic ethanol exposure increases the susceptibility of rat liver to increased injury by 1 or 3 repeat binge. Among other alterations, the activated levels of ERK1, and more so ERK2, were remarkably amplified by binge suggesting a role of these isotypes in the binge amplification of the injury. In contrast, p38 MAPK and JNK1/2 activities were not amplified. These binge-induced changes were also reflected in the increases in the RNA levels for egr-1 and PAI-1. This study offers chronic followed by repeat binge as a model for the study of progression of liver injury by ethanol and highlights the involvement of ERK1 and ERK2 isotypes in the amplification of liver injury by binge ethanol.