New drug targets for alcoholic liver disease

Identification of Novel Peptides with Alcohol Dehydrogenase (ADH) Activating Ability in Chickpea Protein Hydrolysates

Alcohol dehydrogenase (ADH) is one of the main rate-limiting enzymes in alcohol metabolism. Food protein-derived peptides are thought to have ADH activating ability. We verified for the first time that chickpea protein hydrolysates (CPHs) had the ability to activate ADH and identified novel peptides from them. CPHs obtained by hydrolysis with Alcalase for 30 min (CPHs-Pro-30) showed the highest ADH activating ability, and the ADH activation rate could still maintain more than 80% after in vitro simulated gastrointestinal digestion. We have verified four peptides with activation ability to ADH: ILPHF, MFPHLPSF, LMLPHF and FDLPALRF (concentration for 50% of maximal effect (EC₅₀): 1.56 ± 0.07 µM, 1.62 ± 0.23 µM, 1.76 ± 0.03 µM and 9.11 ± 0.11 µM, respectively). Molecular docking showed that the mechanism for activating ADH was due to the formation of a stable complex between the peptide and the active center of ADH through hydrogen bonding. The findings suggest that CPHs and peptides with ADH activating ability may be developed as natural anti-alcoholic ingredients to prevent alcoholic liver disease (ALD).

Current Therapeutic Options and Potential of Mesenchymal Stem Cell Therapy for Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a globally prevalent chronic liver disease caused by chronic or binge consumption of alcohol. The therapeutic efficiency of current therapies for ALD is limited, and there is no FDA-approved therapy for ALD at present. Various strategies targeting pathogenic events in the progression of ALD are being investigated in preclinical and clinical trials. Recently, mesenchymal stem cells (MSCs) have emerged as a promising candidate for ALD treatment and have been tested in several clinical trials. MSC-released factors have captured attention, as they have the same therapeutic function as MSCs. Herein, we focus on current therapeutic options, recently proposed strategies, and their limitations in ALD treatment. Also, we review the therapeutic effects of MSCs and those of MSC-related secretory factors on ALD. Although accumulating evidence suggests the therapeutic potential of MSCs and related factors in ALD, the mechanisms underlying their actions in ALD have not been well studied. Further investigations of the detailed mechanisms underlying the therapeutic role of MSCs in ALD are required to expand MSC therapies to clinical applications. This review provides information on current or possible treatments for ALD and contributes to our understanding of the development of effective and safe treatments for ALD.

Identification of a novel peptide that activates alcohol dehydrogenase from crucian carp swim bladder and how it protects against acute alcohol-induced liver injury in mice

Alcoholism is a severe threat to public health, and there are no adequate treatments for alcoholic liver disease. The aim of this study was to identify bioactive peptides derived from natural proteins that prevent acute alcohol-induced liver injury. We identified a peptide with the sequence Gly-Leu-hydroxyproline-Gly-Glu-Arg (GLpGER) from the hydrolysate of crucian carp swim bladder using size-exclusion chromatography and reversed-phase chromatography. The in vitro EC₅₀ value of GLpGER to activate alcohol dehydrogenase (ADH) was 137.9 ± 9 µM. Molecular docking experiments indicated that the mechanism by which GLpGER activates ADH may be related to the formation of stable complexes with ADH active pockets through hydrogen bonding, and electrostatic and hydrophobic interactions. Oral administration of GLpGER one hour before acute alcohol ingestion significantly increased alcohol metabolism, manifesting as reduced incidence of the loss of righting reflex, increased alcohol tolerance time, shortened sobering time, and decreased blood alcohol concentration level. GLpGER restored liver ADH activity, maintained the typical morphology of hepatocytes, and reduced serum levels of alanine aminotransferase and aspartate aminotransferase. These findings suggest that GLpGER might reduce acute alcohol-induced liver injury and may have the potential to be developed as an anti-inebriation ingredient.

Multiparametric magnetic resonance imaging/magnetic resonance elastography assesses progression and regression of steatosis, inflammation, and fibrosis in alcohol-associated liver disease

BACKGROUND

Magnetic resonance imaging (MRI) and MRI-based elastography (MRE) are the most promising noninvasive techniques in assessing liver diseases. The purpose of this study was to evaluate an advanced multiparametric imaging method for staging disease and assessing treatment response in realistic preclinical alcohol-associated liver disease (ALD).

METHODS

We utilized four different preclinical mouse models in our study: Model 1-mice were fed a fast-food diet and fructose water for 48 weeks to induce nonalcoholic fatty liver disease; Model 2-mice were fed chronic-binge ethanol (EtOH) for 10 days or 8 weeks to induce liver steatosis/inflammation. Two groups of mice were treated with interleukin-22 at different time points to induce disease regression; Model 3-mice were administered CCl4 for 2 to 4 weeks to establish liver fibrosis followed by 2 or 4 weeks of recovery; and Model 4-mice were administered EtOH plus CCl4 for 12 weeks. Mouse liver imaging biomarkers including proton density fat fraction (PDFF), liver stiffness (LS), loss modulus (LM), and damping ratio (DR) were assessed. Liver and serum samples were obtained for histologic and biochemical analyses. Ordinal logistic regression and generalized linear regression analyses were used to model the severity of steatosis, inflammation, and fibrosis, and to assess the regression of these conditions.

RESULTS

Multiparametric models with combinations of biomarkers (LS, LM, DR, and PDFF) used noninvasively to predict the histologic severity and regression of steatosis, inflammation, and fibrosis were highly accurate (area under the curve > 0.84 for all). A three-parameter model that incorporates LS, DR, and ALT predicted histologic fibrosis progression (r = 0.84, p < 0.0001) and regression (r = 0.79, p < 0.0001) as measured by collagen content in livers.

CONCLUSION

This preclinical study provides evidence that multiparametric MRI/MRE can be used noninvasively to assess disease severity and monitor treatment response in ALD.

Alcohol-associated liver disease: A review on its pathophysiology, diagnosis and drug therapy

One of the global burdens of health care is an alcohol-associated liver disease (ALD) and liver-related death which is caused due to acute or chronic consumption of alcohol. Chronic consumption of alcohol damage the normal defense mechanism of the liver and likely to disturb the gut barrier system, mucosal immune cells, which leads to decreased nutrient absorption. Therapy of ALD depends upon the spectrum of liver injury that causes fatty liver, hepatitis, and cirrhosis. The foundation of therapy starts with abstinence from alcohol. Corticosteroids are used for the treatment of ALD but due to poor acceptance, continuing mortality, and identification of tumor necrosis factor-alpha as an integral component in pathogenesis, recent studies focus on pentoxifylline and, antitumor necrosis factor antibody to neutralize cytokines in the therapy of severe alcoholic hepatitis. Antioxidants also play a significant role in the treatment but till today there is no universally accepted therapy available for any stage of ALD. The treatment aspects need to restore the gut functions and require nutrient-based treatments to regulate the functions of the gut system and prevent liver injury. The vital action of saturated fatty acids greatly controls the gut barrier. Overall, this review mainly focuses on the mechanism of alcohol-induced metabolic dysfunction, contribution to liver pathogenesis, the effect of pregnancy, and targeted therapy of ALD.

Interleukin-22 in alcoholic hepatitis and beyond

Alcoholic hepatitis (AH) is a clinical syndrome characterized by jaundice and progressive inflammatory liver injury in patients with a history of prolonged periods of excess alcohol consumption and recent heavy alcohol abuse. Severe AH is a life-threatening form of alcohol-associated liver disease with a high short-term mortality rate around 30-50% at one month from the initial presentation. A large number of pro-inflammatory mediators, metabolic pathways, transcriptional factors and epigenetic factors have been suggested to be associated with the development and progression of AH. Several factors may contribute to liver failure and mortality in patients with severe AH including hepatocyte death, inflammation, and impaired liver regeneration. Although the pathogeneses of AH have been extensively investigated and many therapeutic targets have been identified over the last five decades, no new drugs for AH have been successfully developed. In this review, we discuss interleukin-22 (IL-22) biology and its roles of anti-apoptosis, anti-fibrosis, anti-oxidation, anti-bacterial infection and regenerative stimulation in protecting against liver injury in many preclinical models including several recently developed models such as chronic-plus-binge ethanol feeding, acute-on-chronic liver failure, C-X-C motif chemokine ligand 1 plus high-fat diet-induced nonalcoholic steatohepatitis. Finally, clinical trials of IL-22 for the treatment of AH are also discussed, which showed some promising benefits for AH patients.

An Open-Label, Dose-Escalation Study to Assess the Safety and Efficacy of IL-22 Agonist F-652 in Patients With Alcohol-associated Hepatitis

BACKGROUND AND AIMS

Interleukin-22 has beneficial effects on inflammation and impaired hepatic regeneration that characterize alcohol-associated hepatitis (AH). F-652 is a recombinant fusion protein of human interleukin-22 and immunoglobulin G2 fragment crystallizable. This study aims to assess the safety and efficacy signals of F-652 in patients with moderate and severe AH.

APPROACH AND RESULTS

A phase-2 dose-escalating study was carried out. F-652 (10 μg/kg, 30 μg/kg, or 45 μg/kg) administered on days 1 and 7 was tested in 3 patients each with moderate (Model for End-Stage Liver Disease [MELD] scores: 11-20) and severe AH (MELD scores: 21-28). Safety was defined by absence of serious adverse events and efficacy was assessed by Lille score, changes in MELD score, and serum bilirubin and aminotransferases at days 28 and 42. Three independent propensity-matched comparator patient cohorts were used. Plasma extracellular vesicles and multiplex serum cytokines were measured to assess inflammation and hepatic regeneration. Eighteen patients (9 moderate and 9 severe AH) were enrolled, 66% were male, and the mean age was 48 years. The half-life of F-652 following the first dose was 61-85 hours. There were no serious adverse events leading to discontinuation. The MELD score and serum aminotransferases decreased significantly at days 28 and 42 from baseline (P < 0.05). Day-7 Lille score was 0.45 or less in 83% patients as compared with 6%, 12%, and 56% among the comparator cohorts. Extracellular vesicle counts decreased significantly at day 28 (P < 0.013). Cytokine inflammatory markers were down-regulated, and regeneration markers were up-regulated at days 28 and 42.

CONCLUSIONS

F-652 is safe in doses up to 45 μg/kg and associated with a high rate of improvement as determined by Lille and MELD scores, reductions in markers of inflammation and increases in markers of hepatic regeneration. This study supports the need for randomized placebo-controlled trials to test the efficacy of F-652 in AH.

Interleukin 22 in Liver Injury, Inflammation and Cancer

Interleukin 22(IL-22), a member of the IL-10 cytokine family and is an emerging CD4+Th cytokine that plays an important role in anti-microbial defense, homeostasis and tissue repair. We are interested in IL-22 as it has the double function of suppressing or encouraging inflammation in various disease models including hepatic inflammation. As a survival factor for hepatocytes, IL-22 plays a protective role in many kinds of liver diseases, such as hepatitis, liver fibrosis, or hepatocellular carcinoma (HCC) by binding to the receptors IL-22R1 and IL-10R2. Overexpression of IL-22 reduces liver fibrosis by attenuating the activation of hepatic stellate cell (the main cell types involved in hepatic fibrosis), and down-regulating the levels of inflammatory cytokines. Administration of exogenous IL-22 increases the replication of hepatocytes by inhibiting cell apoptosis and promoting mitosis, ultimately plays a contributing role in liver regeneration. Furthermore, treatment with IL-22 activates hepatic signal transducer and activator of transcription 3 (STAT3), ameliorates hepatic oxidative stress and alcoholic fatty liver, effectively alleviate the liver damage caused by alcohol and toxicant. In conclusion, the hepatoprotective functions and liver regeneration promoting effect of IL-22 suggests the therapeutic potential of IL-22 in the treatment of human hepatic diseases.

Targeting inflammation for the treatment of alcoholic liver disease

Alcoholic liver disease (ALD) is a leading cause of chronic liver disease with a wide spectrum of manifestations including simple steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Liver injury in ALD is caused by chronic inflammation, which has been actively investigated as a therapeutic target for the treatment of ALD for over the last four decades. In this review, we summarize a wide variety of inflammatory mediators that have been shown to contribute to the pathogenesis of ALD, and discuss the therapeutic potential of these mediators for the treatment of ALD.

Probiotics for people with hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a disorder of brain function as a result of liver failure or portosystemic shunt or both. Both hepatic encephalopathy (clinically overt) and minimal hepatic encephalopathy (not clinically overt) significantly impair patient's quality of life and daily functioning, and represent a significant burden on healthcare resources. Probiotics are live micro-organisms, which when administered in adequate amounts, may confer a health benefit on the host.

OBJECTIVES

To determine the beneficial and harmful effects of probiotics in any dosage, compared with placebo or no intervention, or with any other treatment for people with any grade of acute or chronic hepatic encephalopathy. This review did not consider the primary prophylaxis of hepatic encephalopathy.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, conference proceedings, reference lists of included trials, and the World Health Organization International Clinical Trials Registry Platform until June 2016.

SELECTION CRITERIA

We included randomised clinical trials that compared probiotics in any dosage with placebo or no intervention, or with any other treatment in people with hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration. We conducted random-effects model meta-analysis due to obvious heterogeneity of participants and interventions. We defined a P value of 0.05 or less as significant. We expressed dichotomous outcomes as risk ratio (RR) and continuous outcomes as mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 21 trials with 1420 participants, of these, 14 were new trials. Fourteen trials compared a probiotic with placebo or no treatment, and seven trials compared a probiotic with lactulose. The trials used a variety of probiotics; the most commonly used group of probiotic was VSL#3, a proprietary name for a group of eight probiotics. Duration of administration ranged from 10 days to 180 days. Eight trials declared their funding source, of which six were independently funded and two were industry funded. The remaining 13 trials did not disclose their funding source. We classified 19 of the 21 trials at high risk of bias.We found no effect on all-cause mortality when probiotics were compared with placebo or no treatment (7 trials; 404 participants; RR 0.58, 95% CI 0.23 to 1.44; low-quality evidence). No-recovery (as measured by incomplete resolution of symptoms) was lower for participants treated with probiotic (10 trials; 574 participants; RR 0.67, 95% CI 0.56 to 0.79; moderate-quality evidence). Adverse events were lower for participants treated with probiotic than with no intervention when considering the development of overt hepatic encephalopathy (10 trials; 585 participants; RR 0.29, 95% CI 0.16 to 0.51; low-quality evidence), but effects on hospitalisation and change of/or withdrawal from treatment were uncertain (hospitalisation: 3 trials, 163 participants; RR 0.67, 95% CI 0.11 to 4.00; very low-quality evidence; change of/or withdrawal from treatment: 9 trials, 551 participants; RR 0.70, 95% CI 0.46 to 1.07; very low-quality evidence). Probiotics may slightly improve quality of life compared with no intervention (3 trials; 115 participants; results not meta-analysed; low-quality evidence). Plasma ammonia concentration was lower for participants treated with probiotic (10 trials; 705 participants; MD -8.29 μmol/L, 95% CI -13.17 to -3.41; low-quality evidence). There were no reports of septicaemia attributable to probiotic in any trial.When probiotics were compared with lactulose, the effects on all-cause mortality were uncertain (2 trials; 200 participants; RR 5.00, 95% CI 0.25 to 102.00; very low-quality evidence); lack of recovery (7 trials; 430 participants; RR 1.01, 95% CI 0.85 to 1.21; very low-quality evidence); adverse events considering the development of overt hepatic encephalopathy (6 trials; 420 participants; RR 1.17, 95% CI 0.63 to 2.17; very low-quality evidence); hospitalisation (1 trial; 80 participants; RR 0.33, 95% CI 0.04 to 3.07; very low-quality evidence); intolerance leading to discontinuation (3 trials; 220 participants; RR 0.35, 95% CI 0.08 to 1.43; very low-quality evidence); change of/or withdrawal from treatment (7 trials; 490 participants; RR 1.27, 95% CI 0.88 to 1.82; very low-quality evidence); quality of life (results not meta-analysed; 1 trial; 69 participants); and plasma ammonia concentration overall (6 trials; 325 participants; MD -2.93 μmol/L, 95% CI -9.36 to 3.50; very low-quality evidence). There were no reports of septicaemia attributable to probiotic in any trial.

AUTHORS' CONCLUSIONS

The majority of included trials suffered from a high risk of systematic error ('bias') and a high risk of random error ('play of chance'). Accordingly, we consider the evidence to be of low quality. Compared with placebo or no intervention, probiotics probably improve recovery and may lead to improvements in the development of overt hepatic encephalopathy, quality of life, and plasma ammonia concentrations, but probiotics may lead to little or no difference in mortality. Whether probiotics are better than lactulose for hepatic encephalopathy is uncertain because the quality of the available evidence is very low. High-quality randomised clinical trials with standardised outcome collection and data reporting are needed to further clarify the true efficacy of probiotics.