Alcoholic liver injury： Pathological features and models—Role of alcohol in the regulation of iron metabolism

Patients with alcoholic liver disease frequently exhibit increased body iron stores, as reflected by elevated serum iron indices (transferrin saturation, ferritin) and hepatic iron concentration. Even mild to moderate alcohol consumption has been shown to increase the prevalence of iron overload. Moreover, increased hepatic iron content is associated with greater mortality from alcoholic cirrhosis, suggesting a pathogenic role for iron in alcoholic liver disease. Alcohol increases the severity of disease in patients with genetic hemochromatosis, an iron overload disorder common in the Caucasian population. Both iron and alcohol individually cause oxidative stress and lipid peroxidation, which culminates in liver injury. Despite these observations, the underlying mechanisms of iron accumulation and the source of the excess iron observed in alcoholic liver disease remain unclear. Over the last decade, several novel iron-regulatory proteins have been identified and these have greatly enhanced our understanding of iron metabolism. For example, hepcidin, a circulatory antimicrobial peptide synthesized by the hepatocytes of the liver is now known to play a central role in the regulation of iron homeostasis. This review attempts to describe the interaction of alcohol and iron-regulatory molecules. Understanding these molecular mechanisms is of considerable clinical importance because both alcoholic liver disease and genetic hemochromatosis are common diseases, in which alcohol and iron appear to act synergistically to cause liver injury.     

Molecular pathogenesis and clinical conse-quences of iron overload in liver cirrhosis

BACKGROUND: The liver, as the main iron storage compart-ment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Exces-sive accumulation of iron is an important risk factor in liver disease progression to cirrhosis and hepatocellular carcinoma. Here, we review the literature on the molecular pathogenesis of iron overload and its clinical consequences in chronic liver diseases.
DATA SOURCES: PubMed was searched for English-language articles on molecular genesis of primary and secondary iron overload, as well as on their association with liver disease pro-gression. We have also included literature on adjuvant thera-peutic interventions aiming to alleviate detrimental effects of excessive body iron load in liver cirrhosis.
RESULTS: Excess of free, unbound iron induces oxidative stress, increases cell sensitivity to other detrimental factors, and can directly affect cellular signaling pathways, resulting in accelerated liver disease progression. Diagnosis of liver cirrhosis is, in turn, often associated with the identiifcation of a pathological accumulation of iron, even in the absence of genetic background of hereditary hemochromatosis. Iron depletion and adjuvant therapy with antioxidants are shown to cause signiifcant improvement of liver functions in patients with iron overload. Phlebotomy can have beneifcial effects on liver histology in patients with excessive iron accumulation combined with compensated liver cirrhosis of different etiology.
CONCLUSION: Excessive accumulation of body iron in liver cirrhosis is an important predictor of liver failure and avail-able data suggest that it can be considered as target for adju-vant therapy in this condition.     

Alcoholic liver disease and hepatitis C virus infection

Alcohol consumption and hepatitis C virus(HCV) infection have a synergic hepatotoxic effect, and the coexistence of these factors increases the risk of advanced liver disease. The main mechanisms of this effect are increased viral replication and altered immune response, although genetic predisposition may also play an important role. Traditionally, HCV prevalence has been considered to be higher(up to 50%) in alcoholic patients than in the general po pulation. However, the presence of advanc e d alcoholic liver disease(ALD) or intravenous drug use(IDU) may have confounded the results of previous studies, and the real prevalence of HCV infection in alcoholic patients without ALD or prior IDU has been shown to be lower. Due to the toxic combined effect of HCV and alcohol, patients with HCV infection should be screened for excessive ethanol intake. Patients starting treatment for HCV infection should be specifically advised to stop or reduce alcohol consumption because of its potential impact on treatment efficacy and adherence and may benefi t from addi tionalsupport during antiviral therapy. This recommendation might be extended to all currently recommended drugs for HCV treatment. Patients with alcohol dependence and HCV infection, can be treated with acamprosate, nalmefene, topiramate, and disulfiram, although baclofen is the only drug specifically tested for this purpose in patients with ALD and/or HCV infection.     

Risk of hepatocellular carcinoma after hepatitis C virus cure

Hepatitis C virus(HCV)is a significant cause of hepatocellular carcinoma(HCC).The direct-acting antivirals marked a new era of HCV therapy and are associated with greater than 95%cure rate.Successful treatment of chronic hepatitis C greatly reduces the risk of HCC.A proportion of patients,especially those with pre-existing cirrhosis,remain at risk for HCC despite sustained virologic response(SVR).Diabetes mellitus,hepatic steatosis,alcohol consumption and lack of fibrosis regression are associated with risks of HCC after HCV cure.Noninvasive modalities such as aspartate aminotransferase to platelet ratio index and fibrosis-4 index and transient elastography have been used to monitor hepatic fibrosis.More recently,various fibrosis scores have been combined with clinical parameters and other novel biomarkers to predict risks of HCC for patients who achieved SVR.These models still need to be validated and standardized prior to applying to routine clinical care.     

Role of alcohol in pathogenesis of hepatitis B virus infection

Hepatitis B virus(HBV)and alcohol abuse often contribute to the development of end-stage liver disease.Alcohol abuse not only causes rapid progression of liver disease in HBV infected patients but also allows HBV to persist chronically.Importantly,the mechanism by which alcohol promotes the progression of HBVassociated liver disease are not completely understood.Potential mechanisms include a suppressed immune response,oxidative stress,endoplasmic reticulum and Golgi apparatus stresses,and increased HBV replication.Certainly,more research is necessary to gain a better understanding of these mechanisms such that treatment(s)to prevent rapid liver disease progression in alcohol-abusing HBV patients could be developed.In this review,we discuss the aforementioned factors for the higher risk of liver diseases in alcohol-induced HBV pathogenies and suggest the areas for future studies in this field.     

Effects of antiviral therapy on preventing liver tumorigenesis and hepatocellular carcinoma recurrence

Chronic hepatitis B virus(HBV)infection is the key driving force of liver disease progression,resulting in the development of hepatic dysfunction,cirrhosis and hepatocellular carcinoma(HCC).The primary aim of therapy is to suppress or eliminate HBV replication to reduce the activity of hepatitis,thus reducing the risk of,or slowing the progression of,liver disease.Nucleos(t)ide analogues(Nucs)may result in rapid suppression of HBV replication with normalization of serum transaminases and restore liver function,thus increasing survival in patients with hepatic decompensation.Long-term Nuc therapy may result in histological improvement or reversal of advanced fibrosis and reduction in disease progression,including the development of HCC.The long-term benefits of a finite course of interferon(IFN)-αtherapy also include a sustained and cumulative response,as well as hepatitis B surface antigen seroclearance and reduction in the development of cirrhosis and/or HCC.Pegylated IFN and newer Nucs may achieve better long-term outcomes because of improved efficacy and a low risk of drug resistance.However,treatment outcomes are still far from satisfactory.Understanding the effects of anti-HBV treatment against HCC incidence and recurrence after hepatectomy or liver transplantation is required for further improvement of outcome.     

Hepatic non-parenchymal cells: Master regulators of alcoholic liver disease?

Chronic alcohol consumption is one of the most common causes of the progression of alcoholic liver disease(ALD). In the past, alcohol-mediated hepatocyte injury was assumed to be a significantly major cause of ALD. However, a huge number of recent and brilliant studies have demonstrated that hepatic non-parenchymal cells including Kupffer cells, hepatic stellate cells, liver sinusoidal endothelial cells and diverse types of lymphocytes play crucial roles in the pathogenesis of ALD by producing inflammatory mediators such as cytokines, oxidative stress, micro RNA, and lipid-originated metabolites(retinoic acid and endocannabinoids) or by directly interacting with parenchymal cells(hepatocytes). Therefore, understanding the comprehensive roles of hepatic nonparenchymal cells during the development of ALD will provide new integrative directions for the treatment of ALD. This review will address the roles of nonparenchymal cells in alcoholic steatosis, inflammation, and liver fibrosis and might help us to discover possible therapeutic targets and treatments involving modulating the non-parenchymal cells in ALD.     

Hepatocellular carcinoma in the post-hepatitis C virus era: Should we change the paradigm?

Hepatocellular carcinoma (HCC) is a common and deadly malignancy. The disease usually develops on a background of chronic liver disease. Until recently, the most common etiology was infection with the hepatitis C virus (HCV). The advent of direct-acting antiviral (DAA) therapies has been a major breakthrough in HCV treatment. Sustained virologic response can now be achieved in almost all treated patients, even in patients with a high risk for the development of HCC, such as the elderly or those with significant fibrosis. Early reports raised concerns of a high risk for HCC occurrence after DAA therapy both in patients with previous resection of tumors and those without previous tumors. As the World Health Organization’s goals for eradication of HCV are being endorsed worldwide, the elimination of HCV seems feasible. Simultaneous to the decrease in the burden of cirrhosis from HCV, non-alcoholic fatty liver disease (NAFLD) incidence has been increasing dramatically including significant increased incidence of cirrhosis and HCC in these patients. Surprisingly, a substantial proportion of patients with NAFLD were shown to develop HCC even in the absence of cirrhosis. Furthermore, HCC treatment and potential complications are known to be influenced by liver steatosis. These changes in etiology and epidemiology of HCC suggest the beginning of a new era: The post–HCV era. Changes may eventually undermine current practices of early detection, surveillance and management of HCC. We focused on the risk of HCC occurrence and recurrence in the post–HCV era, the surveillance needed after DAA therapy and current studies in HCC patients with NAFLD.     

Alcohol and hepatitis C

Alcohol abuse and hepatitis C virus (HCV) infection coexist with chronic liver disease in many patients. The mechanism of injury in these patients is probably multifactorial and involves, but is not limited to, a combination of diminished immune clearance of HCV, oxidative stress, emergence of HCV quasi-species, hepatic steatosis, increased iron stores, and increased rate of hepatocyte apoptosis. In patients with HCV infection, alcohol consumption is known to cause accelerated progression of liver fibrosis, higher frequency of cirrhosis, and increased incidence of hepatocellular carcinoma (HCC). These patients also have decreased survival as compared with patients with either alcohol abuse or HCV liver injury alone. Alcohol abuse causes decreased response to interferon treatment in HCV patients. It is therefore necessary for patients with HCV infection to abstain from alcohol consumption.     

Hepatitis C and Alcohol

BACKGROUND: Alcohol abuse and hepatitis C virus (HCV) infection frequently coexist in patients with chronic liver disease. It is widely believed that alcohol and HCV act synergistically in these patients to promote the development and progression of liver damage. METHODS: A review of the relevant medical literature, identified by computer assisted literature search, was conducted. RESULTS: It has been established that alcohol consumption is associated with the accelerated progression of liver injury, higher frequency of cirrhosis, and higher incidence of hepatocellular carcinoma. Alcohol abuse is also associated with decreased response to interferon treatment, and there are reports to suggest that patients with HCV cirrhosis, who abuse alcohol, have higher mortality than those who do not. Abstinence may reverse some of these deleterious effects of alcohol, and may even improve the ultimate response to treatment. The mechanism for the synergistic effect of alcohol and HCV is not fully understood, but has been attributed to alcohol's effect on viral replication, or to its effect on the immune system, hepatic iron content, or hepatic regeneration. CONCLUSIONS: Alcohol has a deleterious effect on HCV associated liver disease. It is recommended that patients with HCV infection abstain from alcohol consumption.     

Alcohol use disorder and the liver

Alcohol use disorders (AUD) cause a range of physical harms, but the major cause of alcohol-related mortality is alcohol-related liver disease (ALD), in some countries accounting for almost 90% of alcohol-related deaths. The risk of ALD has an exponential relationship with increasing alcohol consumption, but is also associated with genetic factors, other life-style factors and social deprivation. ALD includes a spectrum of progressive pathology, from liver steatosis to fibrosis and liver cirrhosis. There are no specific treatments for liver cirrhosis, but abstinence from alcohol is key to limit progression of the disease. Over time, cirrhosis can progress (often silently) to decompensated cirrhosis and hepatocellular carcinoma (HCC). Liver transplantation may be suitable for patients with decompensated liver cirrhosis and may also be used as a curative intervention for HCC, but only for a few selected patients, and complete abstinence is a prerequisite. Patients with AUD are also at risk of developing alcoholic hepatitis, which has a high mortality and limited evidence for effective therapies. There is a strong evidence base for the effectiveness of psychosocial and pharmacological interventions for AUD, but very few of these have been trialled in patients with comorbid ALD. Integrated specialist alcohol and hepatology collaborations are required to develop interventions and pathways for patients with ALD and ongoing AUD.     

Mitochondrial reactive oxygen species as a mystery voice in hepatitis C

There are several lines of evidence suggesting that oxidative stress is present in hepatitis C to a greater degree than in other inflammatory liver diseases and is closely related to disease progression. The main production site of reactive oxygen species (ROS) is assumed to be mitochondria, which concept is supported by evidence that hepatitis C virus (HCV) core protein is directly associated with them. The detoxification of ROS also is an important function of the cellular redox homeostasis system. These results draw our attention to how HCV‐induced mitochondrial ROS production is beyond redox regulation and affects the disease progression and development of hepatocellular carcinoma (HCC) in chronic hepatitis C. On the other hand, HCV‐related chronic liver diseases are characterized by metabolic alterations such as insulin resistance, hepatic steatosis and/or iron accumulation in the liver. These metabolic disorders also are relevant to the development of HCC in HCV‐related chronic liver diseases. Here, we review the mechanisms by which HCV increases mitochondrial ROS production and offer new insights as to how mitochondrial ROS are linked to metabolic disorders such as insulin resistance, hepatic steatosis and hepatic iron accumulation that are observed in HCV‐related chronic liver diseases.     

Alcoholic hepatitis and HCV interactions in the modulation of liver disease

Most HCV‐infected patients regularly consume alcohol. Alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection together are the most common causes of liver disease worldwide. Although both factors independently cause liver disease, they synergistically promote rapid liver disease progression with devastating outcomes for patients. This review focuses on the prevalence, clinical characteristics and molecular pathophysiologic mechanisms of HCV infection associated with alcohol abuse. Recent findings have centred on the synergistic effect of alcohol and HCV on viral replication, hepatocyte apoptosis, oxidative stress, alcohol‐induced ‘leaky gut’, miR‐122 and immune dysregulation. Clinical and basic research findings presented here summarize key scientific findings with the aim of highlighting potential areas for new therapies and identifying ways of optimizing current treatments for alcoholics with HCV infection.     

Advancing donor liver age and rapid fibrosis progression following transplantation for hepatitis C

BACKGROUND: Chronic hepatitis C virus (HCV) infection is frequently associated with elevated markers of iron stores. Recessively inherited mutations in the HFE gene are responsible for iron accumulation in most cases of hereditary haemochromatosis and may have a role in HCV infection. They may also be associated with progressive liver fibrosis although this remains controversial. AIMS: To assess the prevalence of HFE mutations in Scottish HCV infected patients and to explore the effect of the carrier state on serum and liver iron stores, and the severity of liver disease. PATIENTS: A total of 164 patients with antibodies to HCV who underwent liver biopsy were assessed prospectively. METHODS: Each patient was screened for HFE mutations (Cys282Tyr and His63Asp). Iron markers were assessed in serum (ferritin, transferrin saturation) and on liver biopsy (stainable iron, liver iron concentration (LIC) and hepatic iron index). RESULTS: There were 67 (41%, 26 Cys282Tyr, 33 His63Asp, eight compound) heterozygotes. Forty four (28%) patients had elevated serum iron markers, 24 (15%) had stainable liver iron, and five (3%) had elevated LICs. Carriage of HFE mutations was not associated with any clinical, biochemical, virological, or pathological features, including accumulation of liver iron. Elevated serum iron markers were associated with male sex, increased alcohol consumption, and increased liver inflammation and fibrosis. Patients with elevated LICs were older, acquired HCV infection earlier, and had more liver inflammation. CONCLUSIONS: Patients with chronic HCV infection frequently have elevated serum iron markers although elevated LICs are uncommon. Elevated serum iron studies and LICs occur in patients with more severe liver disease. Carriage of HFE mutations, although frequently observed in these HCV infected patients, does not have a role in the accumulation of iron or the progression of liver disease in HCV infection.