N-acetyl cysteine in the treatment of alcohol use disorder in patients with liver disease: Rationale for further research

N acetylcysteine in the treatment of alcohol use disorder: a randomized, double-blind, placebo-controlled trial

N-acetyl cysteine (NAC) is a potent antioxidant that modulates glutamatergic signalling which is thought to play a role in alcohol use disorder (AUD). There have been no clinical trials investigating NAC for AUD. We aimed to conduct a 28 day double-blind, placebo-controlled (PL) randomized trial of NAC in the treatment of AUD (NCT03879759). A total of 42 participants with AUD (56% alcohol-related liver disease) were randomized to receive placebo or NAC 2400 mg/day. Feasibility outcomes included treatment retention and adverse events. Primary clinical outcomes included alcohol consumption (heavy drinking days, standard drinks per drinking day). Secondary clinical outcome measures included craving, liver tests, and psychological outcomes. There were no significant differences in overall retention between treatment groups (χ2(1) = 0.14, P = 0.71: 86% vs 76% for placebo and NAC, respectively). The most commonly reported adverse event in NAC-treated individuals included headache (14%). For standard drinks per drinking day, there was a significant overall effect of time (F = 9.18, P < 0.001), no significant effect of treatment (F = 0.75, P = 0.79), and a significant time x treatment (NAC vs PL) effect (F = 2.73, P < 0.05). For number of heavy drinks per day, there was a significant overall effect of time (F = 3.16, P < 0.05) but no significant effect of treatment or time x treatment (P = 0.17). There were no significant NAC vs PL effects on secondary clinical outcome measures. In the first trial of NAC for the management of AUD, NAC appears to be feasible and safe. Although there was a significant effect of NAC vs placebo on some alcohol measures such as drinks per drinking day, there does appear to be a variable pattern of effect across time suggesting that a larger trial incorporating a longer treatment duration is now required to determine efficacy.

Antioxidants ameliorate oxidative stress in alcoholic liver injury by modulating lipid metabolism and phospholipid homeostasis

Alcoholic liver disease (ALD) is a significant risk factor in the global disease burden. The antioxidants vitamin C (Vc) and N-acetyl cysteine (NAC) have shown hepatoprotective effects in preventing and treating ALD. However, the correlation between the improved effect of antioxidants and lipid metabolism is still unclear. In this study, AML12 cells and C57BL/6 mice stimulated with alcohol were used to investigate the protective effects and potential mechanisms of two antioxidants (Vc and NAC) on alcoholic liver injury. Results showed that Vc and NAC attenuated intracellular lipid accumulation and oxidative damage induced by excessive alcohol exposure in hepatic AML12 cells. The in vivo results indicated that antioxidants ameliorated alcohol-induced changes in histopathology, reducing the levels of alcohol metabolizing factors and aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), and total cholesterol (TC) contents, which demonstrated that antioxidants effectively mitigated liver injury in ALD mice. Further studies showed that antioxidants reversed the disruption of fatty acid (FA) synthesis and lipid transport induced by alcohol exposure, and restored phospholipid levels. Especially, Vc and NAC increased the endogenous antioxidant plasmenyl phosphatidylethanolamine (PlsEtn). Additionally, antioxidants ameliorated the alcohol-impaired mitochondrial function and inhibited excessive oxidative stress. In conclusion, antioxidants can regulate lipid metabolism and phospholipid homeostasis, which in turn inhibit oxidative stress and thereby exert protective effects against ALD.

Alcohol and the mechanisms of liver disease

Alcoholic liver disease (ALD), which is a leading cause of morbidity and mortality worldwide, covers a large spectrum of liver injuries ranging from simple steatosis to steatohepatitis, advanced fibrosis, cirrhosis, and hepatocellular carcinoma. The pathogenesis of ALD includes genetic and epigenetic alterations, oxidative stress, acetaldehyde-mediated toxicity and cytokine and chemokine-induced inflammation, metabolic reprogramming, immune damage, and dysbiosis of the gut microbiota. This review discusses the progress in the pathogenesis and molecular mechanism of ALD, which could provide evidence for further research on the potential therapeutic strategies targeting these pathways.

Autophagy, Oxidative Stress, and Alcoholic Liver Disease: A Systematic Review and Potential Clinical Applications

Ethanol consumption triggers oxidative stress by generating reactive oxygen species (ROS) through its metabolites. This process leads to steatosis and liver inflammation, which are critical for the development of alcoholic liver disease (ALD). Autophagy is a regulated dynamic process that sequesters damaged and excess cytoplasmic organelles for lysosomal degradation and may counteract the harmful effects of ROS-induced oxidative stress. These effects include hepatotoxicity, mitochondrial damage, steatosis, endoplasmic reticulum stress, inflammation, and iron overload. In liver diseases, particularly ALD, macroautophagy has been implicated as a protective mechanism in hepatocytes, although it does not appear to play the same role in stellate cells. Beyond the liver, autophagy may also mitigate the harmful effects of alcohol on other organs, thereby providing an additional layer of protection against ALD. This protective potential is further supported by studies showing that drugs that interact with autophagy, such as rapamycin, can prevent ALD development in animal models. This systematic review presents a comprehensive analysis of the literature, focusing on the role of autophagy in oxidative stress regulation, its involvement in organ-organ crosstalk relevant to ALD, and the potential of autophagy-targeting therapeutic strategies.

Zinc-glutathione in Chinese Baijiu prevents alcohol-associated liver injury

Zinc depletion is associated with alcohol-associated liver injury. We tested the hypothesis that increasing zinc availability along with alcohol consumption prevents alcohol-associated liver injury. Zinc-glutathione (ZnGSH) was synthesized and directly added to Chinese Baijiu. Mice were administered a single gastric dose of 6 g/kg ethanol in Chinese Baijiu with or without ZnGSH. ZnGSH in Chinese Baijiu did not change the likeness of the drinkers but significantly reduced the recovery time from drunkenness along with elimination of high-dose mortality. ZnGSH in Chinese Baijiu decreased serum AST and ALT, suppressed steatosis and necrosis, and increased zinc and GSH concentrations in the liver. It also increased alcohol dehydrogenase and aldehyde dehydrogenase in the liver, stomach, and intestine and reduced acetaldehyde in the liver. Thus, ZnGSH in Chinese Baijiu prevents alcohol-associated liver injury by increasing alcohol metabolism timely with alcohol consumption, providing an alternative approach to the management of alcohol-associated drinking.

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.

Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different

In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.

Stress- and drug-induced neuroimmune signaling as a therapeutic target for comorbid anxiety and substance use disorders

Stress and substance use disorders remain two of the most highly prevalent psychiatric conditions and are often comorbid. While individually these conditions have a debilitating impact on the patient and a high cost to society, the symptomology and treatment outcomes are further exacerbated when they occur together. As such, there are few effective treatment options for these patients, and recent investigation has sought to determine the neural processes underlying the co-occurrence of these disorders to identify novel treatment targets. One such mechanism that has been linked to stress- and addiction-related conditions is neuroimmune signaling. Increases in inflammatory factors across the brain have been heavily implicated in the etiology of these disorders, and this review seeks to determine the nature of this relationship. According to the "dual-hit" hypothesis, also referred to as neuroimmune priming, prior exposure to either stress or drugs of abuse can sensitize the neuroimmune system to be hyperresponsive when exposed to these insults in the future. This review completes an examination of the literature surrounding stress-induced increases in inflammation across clinical and preclinical studies along with a summarization of the evidence regarding drug-induced alterations in inflammatory factors. These changes in neuroimmune profiles are also discussed within the context of their impact on the neural circuitry responsible for stress responsiveness and addictive behaviors. Further, this review explores the connection between neuroimmune signaling and susceptibility to these conditions and highlights the anti-inflammatory pharmacotherapies that may be used for the treatment of stress and substance use disorders.

N-acetyl cysteine in the treatment of cannabis use disorder: A systematic review of clinical trials

BACKGROUND AND AIM

Cannabis is the most consumed illicit drug globally, with a high risk of developing cannabis use disorder (CUD). No approved pharmacological treatment exists for CUD, but N-Acetyl Cysteine (NAC) has shown promising results in different clinical studies. This study aims to conduct a systematic review of NAC clinical trials for the treatment of CUD.

METHODS

Systematic review of randomized controlled trials (RCTs) was conducted to determine the effect of NAC for the treatment of cannabis dependence/cannabis use disorder (CUD). Articles were electronically searched across different databases using PubMed, Google Scholar, EMBASE, Cochrane Library, Medline and PsycINFO from inception to June 2021. Several study characteristics, including study duration, sample size, study population and age group, intervention, adverse effects, and outcome measure were extracted. A PICO table was used for data extraction.

RESULTS

We included 08 RCTs in the qualitative analysis. The risk of bias (RoB) was assessed according to Cochrane RoB criteria, and a 5 point grading system according to the Oxford Centre for Evidence-Based Medicine was used to rate the methodological quality (level of evidence) of the included articles. Mild and well-tolerated adverse events were reported in the placebo and NAC group.

CONCLUSIONS

The studies collectively offer mixed results, although the strength of the evidence available on which to make a recommendation is strong. NAC has shown to be effective in promoting abstinence, medication adherence and reducing cannabis use and craving among cannabis dependent users. This review also suggests recommendations for future research.

Crosstalk between Oxidative Stress and Inflammatory Liver Injury in the Pathogenesis of Alcoholic Liver Disease

Alcoholic liver disease (ALD) is characterized by the injury, inflammation, and scarring in the liver owing to excessive alcohol consumption. Currently, ALD is a leading cause for liver transplantation. Therefore, extensive studies (in vitro, in experimental ALD models and in humans) are needed to elucidate pathological features and pathogenic mechanisms underlying ALD. Notably, oxidative changes in the liver have been recognized as a signature trait of ALD. Progression of ALD is linked to the generation of highly reactive free radicals by reactions involving ethanol and its metabolites. Furthermore, hepatic oxidative stress promotes tissue injury and, in turn, stimulates inflammatory responses in the liver, forming a pathological loop that promotes the progression of ALD. Accordingly, accumulating further knowledge on the relationship between oxidative stress and inflammation may help establish a viable therapeutic approach for treating ALD.

New approved and emerging pharmacological approaches to alcohol use disorder: a review of clinical studies

introduction: The number of medications approved for AUD is small and they generally have limited efficacy. We need new pharmacotherapies for the management of AUD.Areas covered: In this review, the authors aim to synthesise literature for new approved and emerging pharmacotherapies for AUD. Recently approved medications include nalmefene, which was approved in Europe and Australia for the purposes of controlled drinking. Baclofen has also been approved in France but not in other countries. Off label medications including topiramate and gabapentin have received significant attention with multiple RCTs and meta-analyses and have widespread use in several countries including the USA. Several novel medications have emerged over the last decade but further work is required to determine their efficacy and safety for the widespread management of AUD.Expert opinion: Despite significant advances in our understanding of the neurobiological basis of factors that contribute to the development and maintenance of AUD, there have been few new AUD medications approved for almost 20 years. There are many challenges to the development and introduction of new pharmacotherapies for AUD. Strategies for improving the translational pipeline include drug repurposing and utilisation of human acute laboratory models.

Efficacy of N-acetylcysteine in the prevention of alcohol relapse-like drinking: Study in long-term ethanol-experienced male rats

Alcohol use disorders are chronic and highly relapsing disorders, thus alcoholic patients have a high rate of recidivism for drug use even after long periods of abstinence. The literature points to the potential usefulness of N-acetylcysteine (NAC) in the management of several substance use disorders probably due to its capacity to restore brain homeostasis of the glutamate system disrupted in addiction. However, there is little evidence in the case of alcohol. The aim of this study was to explore the potential anti-relapse efficacy of NAC using the alcohol deprivation effect (ADE) model in long-term experienced rats. Two experiments were performed in male Wistar rats to: (a) test the efficacy of NAC to prevent relapse and (b) discriminate the best administration schedule (intermittent vs. continuous) for NAC. In the first experiment, animals were implanted with mini-osmotic pumps delivering 0 or 1 mg/hr NAC during 14 days. In a second experiment, rats received 0, 60, or 100 mg/kg once daily by subcutaneous injection. The efficacy to prevent ADE was evaluated in both experiments. NAC subcutaneously administered, either by continuous infusion or by intermittent injections regimen, is able to block the ADE. The best results were obtained after using 60 mg/kg NAC dose. Our findings support the hypothesis that NAC may represent a valuable therapy in the management of alcohol relapse.

Suppression of cirrhosis-related renal injury by N-acetyl cysteine

Cirrhosis-induced renal injury or cholemic nephropathy (CN) is a serious clinical complication with poor prognosis. CN could finally lead to renal failure and the need for organ transplantation. Unfortunately, there is no specific pharmacological intervention against CN to date. On the other hand, various studies mentioned the role of oxidative stress and mitochondrial impairment in the pathogenesis of CN. The current study aimed to evaluate the potential protective effects of NAC as a thiol-reducing agent and antioxidant in CN. Bile duct ligation (BDL) was used as a reliable animal model of cholestasis. BDL animals received NAC (0.25% and 1% w: v) in drinking water for 28 consecutive days. Finally, urine, blood, and kidney samples were collected and analyzed. Significant elevation in serum biomarkers of renal injury, along with urine markers of kidney damage, was evident in the BDL group. Moreover, markers of oxidative stress, including reactive oxygen species (ROS) formation, lipid peroxidation, protein carbonylation, and increased oxidized glutathione (GSSG) were evident detected in the kidney of cholestatic rats. Renal tissue antioxidant capacity and reduced glutathione (GSH) were also significantly depleted in the BDL group. Significant mitochondrial depolarization, depleted ATP content, and mitochondrial permeabilization was also detected in mitochondria isolated from the kidney of cholestatic animals. Renal histopathological alterations consisted of significant tissue fibrosis, interstitial inflammation, and tubular atrophy. It was found that NAC (0.25 and 1% in drinking water for 28 consecutive days) blunted histopathological changes, decreased markers of oxidative stress, and improved mitochondrial indices in the kidney of cirrhotic rats. Moreover, serum and urine biomarkers of renal injury were also mitigated in upon NAC treatment. These data indicate a potential renoprotective role for NAC in cholestasis. The effects of NAC on cellular redox state and mitochondrial function seem to play a fundamental role in its renoprotective effects during CN.

Selective luminescence determination of cysteine by using terbium-modified silver nanoparticles or terbium-modified graphene quantum dots

Two methods for the luminescence determination of cysteine (Cys) are presented. They make use of either silver nanoparticles (Ag NPs) or graphene quantum dots (GQDs), both doped with terbium(III). The methods are based on the finding that Cys quenches the green luminescence of Tb(III)-Ag NPs and Tb(III)-GQDs. The excitation/emission maxima are at 306/545 and 257/545 nm, for both nanoprobes, respectively. Response is linear in the 0.28-5.0 μg mL^-1 Cys concentration range for the Tb(III)-Ag NP system, and from 0.05-3.0 μg mL^-1 for the Tb(III)-GQD system. The respective limits of detection are 0.09 and 0.015 μg mL^-1. The probes were applied to the time-resolved luminometric determination of Cys in (spiked) food supplements and gave satisfactory results. Graphical abstractSchematic representation of the quenching by cysteine (Cys) of the time-resolved luminescence (TSL) of terbium-graphene quantum dots [Tb(III)-GQD] and of terbium-silver nanoparticles [Tb(III)-Ag NP].

Growing burden of alcoholic liver disease in China: A review

Explosive economic growth and increasing social openness in China over the last 30 years have significantly boosted alcohol consumption, and consequently, the incidence of alcoholic liver disease (ALD) in China has increased. Because the epidemiologic and clinical features of ALD in the Chinese population may differ from those of the Caucasian population, this review describes the epidemiology, pathogenesis, genetic polymorphisms, diagnosis, and treatment of ALD in the Chinese population. This updated knowledge of ALD in China provides information needed for a global understanding of ALD and may help in the development of useful strategies for reducing the global ALD burden.

Medication Development for Alcohol Use Disorder: A Focus on Clinical Studies

Compared to other medical disorders, including other brain diseases, the number of medications approved for alcohol use disorder (AUD) is very small. Disulfiram, naltrexone (oral and long-acting), and acamprosate are approved by the US Food and Drug Administration (FDA) to treat patients with AUD. These medications are also approved in other countries, including in Europe, where the European Medicines Agency (EMA) also approved nalmefene for AUD. Furthermore, baclofen was recently approved for AUD in France. These approved medications have small effect sizes, which are probably the consequence of the fact that they only work for some patients, yet a personalized approach to match the right medication with the right patient is still in its infancy. Therefore, research is needed to expand the armamentarium of medications that clinicians can use to treat their patients, as well as to better develop personalized approaches. This book chapter reviews other medications, beyond those approved by the FDA, that have shown efficacy in clinical trials, as well as medications which are still in the early stages of evaluation in human studies.