Roles of alcohol consumption in fatty liver: a longitudinal study

Changes in drinking levels and metabolic dysfunction-associated steatotic liver disease: a longitudinal study from the China multi-ethnic cohort study

BACKGROUND

Little is known about the associations of changes in drinking levels with the newly defined metabolic dysfunction-associated steatotic liver disease (MASLD). We therefore sought to estimate the associations between changes in drinking levels and MASLD in less developed regions of China.

METHODS

This longitudinal study included 8727 participants from the China Multi-Ethnic Cohort (CMEC) in less developed regions, all participating in baseline and a follow-up survey. MASLD was defined as hepatic steatosis, along with the presence of at least one of five cardiometabolic risks, in addition to limiting excessive alcohol consumption. We applied the parametric g-formula to evaluate the association between changes in drinking levels and MASLD. We further estimated the association between changes in drinking levels and fibrosis scores (AST-to-platelet ratio and fibrosis-4 index) in patients with MASLD.

RESULTS

Compared with sustained non-drinking, sustained modest drinking was associated with a higher risk of MASLD (Mean Ratio (MR): 1.127 [95% CI: 1.040-1.242]). Compared to sustained non-drinking, the MR for those transitioning from non-drinking to modest drinking was 1.065 [95% CI: 0.983-1.169], while the MR for those changing from modest drinking to non-drinking was 1.059 [95% CI: 0.965, 1.173]. Non-invasive fibrosis scores tended to increase with modest drinking compared to sustained non-drinking.

CONCLUSION

In the less developed regions of China, sustained moderate drinking was associated with the risk of MASLD compared with sustained non-drinking. Increased drinking showed a trend towards a higher risk of MASLD. This study can inform drinking policies related to MASLD and liver fibrosis in less developed regions.

MetALD: Clinical aspects, pathophysiology and treatment

Metabolic dysfunction-associated steatotic liver disease (MASLD) and alcohol-related liver disease (ALD) are the most prevalent causes of chronic liver disease worldwide. Both conditions have many pathophysiological mechanisms in common, such as altered lipid and bile acid metabolism, and share some similar clinical features. Furthermore, metabolic risk factors and alcohol often co-exist in the same individuals and have recently been shown to act synergistically to markedly increase the risk of liver disease. Given the high prevalence and impact of this interaction, steatotic liver disease due to the combination of metabolic dysfunction and moderate-to-high alcohol intake has been termed MetALD in the new steatotic liver disease nomenclature, attracting the interest of the scientific community. Subsequent studies have investigated the prevalence of MetALD, which ranges from 1.7% to 17% in cohorts of patients with steatotic liver disease, depending on the population setting and study design. A few cohort studies have also assessed the prognosis of this patient population, with preliminary data suggesting that MetALD is associated with an intermediate risk of liver fibrosis, decompensation and mortality among steatotic liver disease subtypes. In this review article, we examine the clinical evidence and the experimental models of MetALD and discuss the clinical implications of the term for early detection and management. We provide insight into the pathophysiological mechanisms of the synergistic effect of alcohol and metabolic risk factors, possible screening strategies, the use of biomarkers and emerging models of care, as well as potential therapeutic interventions with a special focus on medications for MASLD, highlighting the most promising drugs for patients with MetALD.

Associations of an overall healthy lifestyle with the risk of metabolic dysfunction-associated fatty liver disease

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) affects up to one-third of the global population. Since no approved pharmacotherapy for MAFLD is available, lifestyle modification remains the cornerstone of clinical care. Our study aims to evaluate the association of an overall healthy lifestyle with MAFLD risk.

METHODS

We conducted an analysis of 327,387 participants from UK biobank. An overall healthy lifestyle score including six evidence-based lifestyles (diet, alcohol consumption, physical activity, sedentary behavior, sleep, and smoking) was assessed by questionnaires. MAFLD and its subtypes were diagnosed by blood biochemistry, ICD codes, and medication information from touchscreen and verbal interview. The prevalence ratios (PRs) and risk ratios (RRs) were estimated by Poisson regression models with robust variance.

RESULTS

In the cross-sectional analysis, the PR (95% CI) was 0.83 (0.83 to 0.84) for MAFLD, and 0.83 (0.83 to 0.84) for MAFLD-overweight/obesity (MAFLD-O), 0.68 (0.66 to 0.70) for MAFLD-lean/normal weight and metabolic dysfunction (P-value for heterogeneity < 0.001), and 0.71 (0.71 to 0.72) for MAFLD-type 2 diabetes mellitus (MAFLD-T2D); and 0.68 (0.66 to 0.71) for dual (or more) etiology fatty liver disease (MAFLD-dual) and 0.83 (0.83 to 0.84) for single etiology MAFLD (MAFLD-single) (P-value for heterogeneity < 0.001) for one additional point in the overall healthy lifestyle score. During a median follow-up of 4.4 years, the RR (95% CI) was 0.83 (0.81 to 0.85) for MAFLD, and 0.83 (0.81 to 0.85) for MAFLD-O, 0.71 (0.62 to 0.81) for MAFLD-L, and 0.68 (0.64 to 0.72) for MAFLD-T2D (P-value for heterogeneity < 0.001); and 0.83 (0.81 to 0.85) for MAFLD-dual and 0.70 (0.58 to 0.85) for MAFLD-single (P-value for heterogeneity = 0.08) for one additional point in the overall healthy lifestyle score. These findings were validated in a prospective analysis among 15,721 participants with revisit data, and also supported by fatty liver index and proton density fat fraction data.

CONCLUSIONS

An overall healthy lifestyle that includes six evidence-based factors was strongly associated with lower MAFLD risk, especially the subtypes with multiple etiologies.

Clinical Characteristics of Steatotic Liver Disease Categories in a Large Cohort of Japanese Health Checkup Participants

Background and Aims

The clinical characteristics and risk factors involved in the development of liver fibrosis in the subtypes of steatotic liver disease (SLD) remain unknown. We examined the clinical characteristics of SLD subtypes using a large Japanese cohort.

Methods

We performed a cross-sectional analysis (total n = 108,446). In this cohort, SLD was diagnosed by ultrasonography. Individuals with none of the cardiometabolic risk factors were excluded.

Results

According to their nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated steatotic liver disease (MASLD) status based on the database, participants with cardiometabolic criteria were allocated to the MASLD, MASLD with increased alcohol intake (MetALD), and alcohol-associated liver disease (ALD) with metabolic dysfunction groups. Of 30,857 subjects with SLD, 21,488 (69.6%) had NAFLD, and 20,922 (67.8%) had MASLD. There were few differences in the clinical characteristics between NAFLD and MASLD. After adjustment for clinical variables, we found that male patients with MetALD [odds ratio (OR) 2.26; 95% confidence interval (CI) 1.87-2.84] and ALD with metabolic dysfunction (OR 3.92; 95% CI 2.85-5.39) had a significantly higher risk for advanced liver fibrosis (diagnosed by Fibrosis-4 (FIB-4) index >2.67) compared to those with MASLD. In female patients with ALD, metabolic dysfunction (OR 5.80; 95% CI 2.51-13.4) and systemic blood pressure of ≥130 mmHg were significant risk factors for high FIB-4 (males: OR 3.38, 95% CI 2.51-4.55; females: OR 4.34, 95% CI 2.66-7.07, P < .001).

Conclusion

Alcohol intake and systolic blood pressure are independent contributors to liver fibrosis progression assessed by FIB-4 in SLD.

Role of Neutrophils in the Development of Steatotic Liver Disease

This review explores the biological aspects of neutrophils, their contributions to the development of steatotic liver disease, and their potential as therapeutic targets for the disease. Although alcohol-associated and metabolic dysfunction-associated liver diseases originate from distinct etiological factors, the two diseases frequently share excessive lipid accumulation as a common contributor to their pathogenesis, thereby classifying them as types of steatotic liver disease. Dysregulated lipid deposition in the liver induces hepatic injury, triggering the activation of the innate immunity, partially through neutrophil recruitment. Traditionally recognized for their role in microbial clearance, neutrophils have recently garnered attention for their involvement in sterile inflammation, a pivotal component of steatotic liver disease pathogenesis. In conclusion, technological innovations, including single-cell RNA sequencing, have gradually disclosed the existence of various neutrophil subsets; however, how the distinct subsets of neutrophil population contribute differentially to the development of steatotic liver disease remains unclear.

Changing landscape of alcohol-associated liver disease in younger individuals, women, and ethnic minorities

Alcohol use is the most important determinant of the development of alcohol-associated liver disease (ALD) and of predicting long-term outcomes in those with established liver disease. Worldwide, the amount, type, and pattern of use of alcohol vary. Alcohol use and consequent liver disease have been increasing in certain ethnic groups especially Hispanics and Native Americans, likely due to variations in genetics, cultural background, socio-economic status, and access to health care. Furthermore, the magnitude and burden of ALD have been increasing especially in the last few years among females and young adults who are at the prime of their productivity. It is critical to recognize the problem and care for these patients integrating cultural aspects in liver clinics. At the federal level, a societal approach is needed with the implementation of public health policies aiming to reduce alcohol consumption in the community. By addressing these challenges and promoting awareness, we can strive to reduce the burden of ALD, especially in high-risk demographic groups to improve their long-term health outcomes. Finally, we need studies and quality research examining these changing landscapes of demographics in ALD as a basis for developing therapeutic targets and interventions to reduce harmful drinking behaviours in these high-risk demographic groups.

Interactions between the metabolic syndrome and alcohol consumption increases the risk of liver disease

Alcohol-related liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD, recently renamed metabolic dysfunction-associated steatotic liver disease [MASLD]) share many features, including certain pathophysiological mechanisms, susceptibility genes, and histological lesions. However, the natural history of the two diseases, studied separately, is significantly different, with ALD being associated with a higher risk of cirrhosis and liver-related mortality. Moreover, evidence suggests an interactive effect between ALD and metabolic risk factors that are associated with NAFLD on the risk of progressive fibrosis and development of cirrhosis. Patients with both a high consumption of alcohol and metabolic risk factors, such as obesity or diabetes, should therefore be considered a particularly high-risk group for cirrhosis. Additional studies regarding the efficacy of screening for advanced liver fibrosis or cirrhosis in these risk groups are needed. The most effective and established method for reducing the risk of progression in ALD is alcohol abstinence, whereas weight loss is effective in NAFLD. In this narrative review, we introduce the reader to the literature of the field and present key studies showing this interactive effect.

Effect of Low-Dose Alcohol Consumption on Chronic Liver Disease

Although alcohol is one of the most important etiologic agents in the development of chronic liver disease worldwide, also recognized as a promoter of carcinogenesis, several studies have shown a beneficial effect of moderate consumption in terms of reduced cardiovascular morbidity and mortality. Whether this benefit is also present in patients with liver disease due to other causes (viral, metabolic, and others) is still debated. Although there is no clear evidence emerging from guidelines and scientific literature, total abstention from drinking is usually prescribed in clinical practice. In this review, we highlight the results of the most recent evidence on this controversial topic, in order to understand the effect of mild alcohol use in this category of individuals. The quantification of alcohol intake, the composition of the tested populations, and the discrepancy between different works in relation to the outcomes represent important limitations emerging from the scientific literature. In patients with NAFLD, a beneficial effect is demonstrated only in a few works. Even if there is limited evidence in patients affected by chronic viral hepatitis, a clear deleterious effect of drinking in determining disease progression in a dose-dependent manner emerges. Poor data are available about more uncommon pathologies such as hemochromatosis. Overall, based on available data, it is not possible to establish a safe threshold for alcohol intake in patients with liver disease.

Is There a Safe Alcohol Consumption Limit for the General Population and in Patients with Liver Disease?

Excessive alcohol consumption represents an important burden for health systems worldwide and is a major cause of liver- and cancer-related deaths. Alcohol consumption is mostly assessed by self-report that often underestimates the amount of drinking. While alcohol use disorders identification test - version C is the most widely used test for alcohol use screening, in patients with liver disease the use of alcohol biomarker could help an objective assessment. The amount of alcohol that leads to significant liver disease depends on gender, genetic background, and coexistence of comorbidities (i.e., metabolic syndrome factors). All patients with alcohol-associated liver disease are recommended to follow complete abstinence and they should be treated within multidisciplinary teams. Abstinence slows down and even reverses the progression of liver fibrosis and can help recompensate patients with complicated cirrhosis. Whether there is a safe amount of alcohol in the general population is a matter of intense debate. Large epidemiological studies showed that the safe amount of alcohol to avoid overall health-related risks is lower than expected even in the general population. Even one drink per day can increase cancer-related death. In patients with any kind of chronic liver disease, especially in those with metabolic-associated steatotic liver disease, no alcohol intake is recommended. This review article discusses the current evidence supporting the deleterious effects of small-to-moderate amounts of alcohol in the general population and in patients with underlying chronic liver disease.

ACG Clinical Guideline: Alcohol-Associated Liver Disease

ABSTRACT

Alcohol-associated liver disease (ALD) is the most common cause of advanced hepatic disease and frequent indication for liver transplantation worldwide. With harmful alcohol use as the primary risk factor, increasing alcohol use over the past decade has resulted in rapid growth of the ALD-related healthcare burden. The spectrum of ALD ranges from early asymptomatic liver injury to advanced disease with decompensation and portal hypertension. Compared with those with other etiologies of liver disease, patients with ALD progress faster and more often present at an advanced stage. A unique phenotype of advanced disease is alcohol-associated hepatitis (AH) presenting with rapid onset or worsening of jaundice, and acute on chronic liver failure in severe forms conveying a 1-month mortality risk of 20%-50%. The model for end stage disease score is the most accurate score to stratify AH severity (>20 defined as severe disease). Corticosteroids are currently the only available therapeutic with proven efficacy for patients with severe AH, providing survival benefit at 1 month in 50%-60% of patients. Abstinence of alcohol use, a crucial determinant of long-term outcomes, is challenging to achieve in ALD patients with concurrent alcohol use disorder (AUD). As patients with ALD are rarely treated for AUD, strategies are needed to overcome barriers to AUD treatment in patients with ALD and to promote a multidisciplinary integrated care model with hepatology, addiction medicine providers, and social workers to comprehensively manage the dual pathologies of liver disease and of AUD. Liver transplantation, a definitive treatment option in patients with advanced cirrhosis, should be considered in selected patients with AH, who are unresponsive to medical therapy and have a low risk of relapse to posttransplant alcohol use. Level of evidence and strength of recommendations were evaluated using the Grading of Recommendations, Assessment, Development, and Evaluations system. This guideline was developed under the American College of Gastroenterology Practice Parameters Committee.

Fatty Liver Change in Older Adults as an Important Risk Factor for Type 2 Diabetes: A Nationwide Cohort Study

OBJECTIVE

To examine the association between changes in fatty liver disease (FLD) over time and the risk of type 2 diabetes in elderly individuals with prediabetes.

METHODS

A total of 156,984 elderly individuals with prediabetes who underwent national health screening in 2009 and 2011 were followed up through December 31, 2019. The FLD status was defined as a change in the fatty liver index. Prediabetes was defined as impaired fasting glucose levels at baseline. Multivariable Cox proportional hazards regression was used to calculate the hazard ratio and CIs for type 2 diabetes according to the changes in FLD.

RESULTS

During a median of 8.35 years of follow-up, type 2 diabetes developed in 29,422 (18.7%) elderly individuals with prediabetes. Multivariable adjusted hazard ratio of type 2 diabetes according to FLD change was 2.22 (95% CI, 2.11 to 2.34) in individuals with persistent FLD compared with those who have never had FLD. Although overall weight loss of 5% or more was associated with a 7% lower risk of type 2 diabetes in total participants, fatty liver status was important. Even with weight loss, those with a history of fatty liver-resolved FLD, new FLD, or persistent FLD-had an increased risk of type 2 diabetes. The risk of type 2 diabetes did not increase in individuals with sustained FLD-free status, regardless of weight change.

CONCLUSION

The presence and change of FLD are important factors for the development of type 2 diabetes in elderly individuals with prediabetes.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

Prevalence and associated metabolic factors of nonalcoholic fatty liver disease in the general population from 2014 to 2018 in Japan: A large-scale multicenter retrospective study

AIM

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. The aim of this study was to determine the recent prevalence and clinical characteristics of NAFLD in Japan.

METHODS

This study initially included 410 061 retrospectively enrolled adults from the medical health checkup registry for metabolic syndrome, chronic kidney disease, and fatty liver in Japan (MIRACLE-J; UMIN-CTR no. UMIN000049419), who were evaluated between 2014 and 2018 at 13 health centers in Japan. Individuals consuming >20 g of alcohol/day or with chronic liver disease were excluded. Fatty liver was diagnosed by ultrasonography. The probability of NAFLD with advanced fibrosis was estimated based on the fibrosis-4 index and NAFLD fibrosis score.

RESULTS

A total of 71 254 participants were included in the final analysis. The overall prevalence of NAFLD was 25.8%. There was a significant, twofold difference in NAFLD prevalence between men (37.4%) and women (18.1%). Nonalcoholic fatty liver disease prevalence increased linearly with body mass index, triglycerides, and low-density lipoprotein cholesterol regardless of threshold values, even in the absence of obesity. Among patients with NAFLD, 14% had diabetes mellitus, 31% had hypertension, and 48% had dyslipidemia. The estimated prevalence of NAFLD with advanced fibrosis was 1.7% and 1.0% according to the fibrosis-4 index and NAFLD fibrosis score, respectively.

CONCLUSIONS

The prevalence of NAFLD was approximately one-quarter of the general population in Japan. There was a linear relationship between NAFLD prevalence and various metabolic parameters, even in nonobese participants. The prevalence of NAFLD with advanced fibrosis was estimated to be 1%-2%.

Non-metabolic causes of steatotic liver disease

Hepatic steatosis is caused by exaggerated hepatic lipid accumulation and is a common histological and radiological finding. Non-alcoholic fatty liver disease (NAFLD), or metabolic dysfunction associated steatotic liver disease (MASLD), is highly associated with metabolic syndrome and represents the most common cause of hepatic steatosis. However, since several comorbidities, lifestyle factors, and drugs can cause hepatic steatosis, MASLD is, to some extent, a diagnosis of exclusion. Nevertheless, initiatives have been taken to encompass positive (instead of negative) criteria for diagnosis - such as the presence of cardiometabolic risk factors together with hepatic steatosis. Nonetheless, before confirming a patient with MASLD, it is essential to map and evaluate other causes of fatty liver disease or steatotic liver disease. Several causes of hepatic steatosis have been identified in studies; however, the study cohorts are scarce and often anecdotal. Additionally, many studies have shown correlation without proving causation, and many are retrospective without reporting relevant patient characteristics and comorbidities - making it difficult to draw conclusions regarding the underlying etiology or present comorbidity of hepatic steatosis. In this narrative review, we aimed to identify and summarize present studies evaluating the impact of the most common and often suggested causes of hepatic steatosis.

The effect of obstructive sleep apnea on fatty liver disease may be obscured by alcohol consumption: An ordinal logistic regression analysis

BACKGROUND

Obstructive sleep apnea (OSA) is closely associated with non-alcoholic fatty liver disease (NAFLD). The current definition of NAFLD cannot exclude the involvement of alcohol consumption in the development of fatty liver disease (FLD), but alcohol can aggravate OSA and participate in steatosis. There is limited evidence on the relationship between OSA and alcohol and its effect on FLD severity.

OBJECTIVE

To determine the effect of OSA on FLD severity based on ordinal responses, and its relationship with alcohol consumption, in order to develop strategies for the prevention and treatment of FLD.

METHODS

Patients with chief complaints of "snoring" who underwent polysomnography and abdominal ultrasound between January 2015 and October 2022 were selected. A total of 325 cases were divided into three groups according to abdominal ultrasound results: no FLD (n = 66), mild FLD (n = 116), and moderately severe FLD (n = 143) group. Patients were also categorized into alcoholic and nonalcoholic groups. Univariate analysis was used to examine the correlation between OSA and FLD severity. Multivariate ordinal logistic regression analysis was further used to identify the determinants of FLD severity and differences between the alcoholic and nonalcoholic groups.

RESULTS

A higher proportion of moderately severe FLD was observed in the group with an apnea/hypopnea index (AHI) > 30 compared to the AHI<15 group in all participants and in the nonalcoholic population (all p < 0.05). There was no significant difference among these groups in the alcoholic population. Ordinal logistic regression analysis found that in all participants, age [OR = 0.966(0.947-0.986)], BMI [OR = 1.293 (1.205-1.394)], diabetes mellitus [OR = 1.932(1.132-3.343)], hyperlipidemia [OR = 2.432(1.355-4.464)], severe OSA [OR = 2.36(1.315-4.259)] (all p < 0.05) were the independent risk factors for more severe FLD. However, different risk factors applied according to alcohol consumption. In addition to age and BMI, the independent risk factors for the alcoholic group also included diabetes mellitus [OR = 3.323(1.494-7.834)] while in the non-alcoholic group risk factors included hyperlipidemia [OR = 4.094(1.639-11.137)], and severe OSA[OR = 2.956(1.334-6.664)] (all p < 0.05).

CONCLUSION

Severe OSA is an independent determinant for developing more severe NAFLD in nonalcoholic population, and alcohol consumption may obscure the effect of OSA on the progression of FLD.

Sex and Tumor-Site Differences in the Association of Alcohol Intake With the Risk of Early-Onset Colorectal Cancer

PURPOSE

Given the increasing incidence of early-onset colorectal cancer (CRC; diagnosed before age 50 years) worldwide, it is important to identify modifiable risk factors. We investigated whether alcohol consumption in the young population correlated with an increased early-onset CRC risk that differed by tumor location and sex.

PATIENTS AND METHODS

We investigated the association between average daily alcohol consumption and the risk of early-onset CRC among 5,666,576 individuals age 20-49 years using data from the Korean National Health Insurance Service (2009-2019). Alcohol consumption levels of nondrinker, light (reference), moderate, and heavy drinker were defined as 0, <10, 10 to <30, and ≥30 g/d for men and 0, <10, 10 to <20, and ≥20 g/d for women, respectively. Multivariate Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs) with 95% CIs.

RESULTS

We identified 8,314 incident early-onset CRC cases during the follow-up period. Moderate and heavy drinkers showed an increased risk of early-onset CRC compared with light drinkers (aHR, 1.09 [95% CI, 1.02 to 1.16] and aHR, 1.20 [95% CI, 1.11 to 1.29], respectively). Subgroup analysis by tumor location showed positive dose-response significance for early-onset distal colon and rectal cancers, but not for proximal colon cancer. The dose-response association between drinking frequency and risk of early-onset CRC was significant, with a 7%, 14%, and 27% increased risk for 1-2, 3-4, and ≥5 d/wk compared with nondrinkers, respectively.

CONCLUSION

Excessive alcohol consumption increases the risk of CRC onset before age 50 years. Thus, effective interventions are required to discourage alcohol consumption among young people and to tailor CRC screening approaches for high-risk individuals.

Research Priorities for Precision Medicine in NAFLD

NAFLD is a multisystem condition and the leading cause of chronic liver disease globally. There are no approved NAFLD-specific dugs. To advance in the prevention and treatment of NAFLD, there is a clear need to better understand the pathophysiology and genetic and environmental risk factors, identify subphenotypes, and develop personalized and precision medicine. In this review, we discuss the main NAFLD research priorities, with a particular focus on socioeconomic factors, interindividual variations, limitations of current NAFLD clinical trials, multidisciplinary models of care, and novel approaches in the management of patients with NAFLD.

Antibody to hepatitis B virus core antigen positivity is a predictor of non-alcoholic fatty liver disease severity

Insufficient information is available about co-factors favoring the progression of non-alcoholic fatty liver disease (NAFLD) toward cirrhosis. We aimed to evaluate the impact of a limited alcohol intake and of occult hepatitis B virus (HBV) infection (OBI) on the severity of NAFLD. Three-hundred-seventy-four alcohol non-abusers and HBV surface antigen negative NAFLD patients (223 males; mean age 55.4 years), consecutively admitted to the outpatients clinic of a referral liver unit from January 1st, 2018 to December 31st, 2019, were studied. Anti-HBV core antigen antibody [(anti-HBc), a surrogate marker of OBI] was assessed in all patients. Patients were distinguished between teetotal and moderate alcohol consumers (intake of less than 30 g and 20 g if males or females, respectively). Liver fibrosis was non-invasively assessed by FIB-4 and transient elastography. Uni- and multivariate analyses were performed to identify predictors of advanced fibrosis. Patients had a mean BMI of 28.5 kg/m², and the majority presented metabolic and cardio-vascular comorbidities [258 patients (69%) had insulin resistance/diabetes, 249 (66.6%) dyslipidemia, 200 (53.5%) arterial hypertension]. Multivariate analysis showed that anti-HBc positivity (p = 0.046, OR 2.153) was a factor associated with advanced fibrosis at FIB-4 score testing, whereas moderate alcohol intake was not associated with severe NAFLD both at FIB-4 and transient elastography evaluations. The study showed that a moderate alcohol intake has no impact on NAFLD severity and suggested that OBI might negatively affect the NAFLD outcome.

Lifestyle changes during the coronavirus disease 2019 pandemic impact metabolic dysfunction-associated fatty liver disease

BACKGROUND AND AIMS

The coronavirus disease 2019 (COVID-19) pandemic precipitated lifestyle changes. We aimed to clarify whether COVID-19-induced lifestyle changes affected the development of metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

This retrospective longitudinal study included 973 participants who underwent health check-ups between 2018 and 2020. We used data from the MedCity21 health examination registry. Participants' clinical characteristics and lifestyle habits were investigated. Independent lifestyle predictors of MAFLD development before the pandemic (2018-2019) and during the pandemic (2019-2020) were identified using logistic regression analysis.

RESULTS

In 2018, 261 (27%) patients were diagnosed with MAFLD. Before the pandemic, 22 patients developed new MAFLD. During this time, routine late-night meals were identified as an independent lifestyle predictor of MAFLD development (hazard ratio [HR] 2.54, 95% confidence interval [CI] 1.02-6.36, P = .046). In contrast, 44 patients developed new MAFLD during the pandemic. During this time, higher daily alcohol intake was identified as an independent lifestyle predictor of MAFLD development (HR 1.03, 95% CI 1.01-1.05, P = .008). In participants aged <60 years, daily alcohol intake and the proportion of participants who ate 2 times/day were significantly higher in patients who developed MAFLD during the pandemic than in those who did not. In participants aged ≥60 years, no lifestyle habits were associated with MAFLD development before or during the pandemic.

CONCLUSIONS

New MAFLD diagnoses increased during the COVID-19 pandemic. Changes in lifestyle factors, particularly in those aged <60 years, must be monitored and addressed as the pandemic continues.

Lifestyle and metabolic factors for nonalcoholic fatty liver disease: Mendelian randomization study

The risk factors for nonalcoholic fatty liver disease (NAFLD) have not been clearly identified. We conducted a Mendelian randomization (MR) study to explore this. Independent genetic variants strongly associated with 5 lifestyle and 9 metabolic factors were selected as instrumental variables from corresponding genome-wide association studies (GWASs). Summary-level data for NAFLD were obtained from a GWAS meta-analysis of 8434 cases and 770,180 non-cases (discovery dataset) and another GWAS meta-analysis of 1483 cases and 17,781 non-cases (replication dataset). Univariable and multivariable MR analyses were performed. There were associations with NAFLD for lifetime smoking index (odds ratio (OR) 1.59, 95% confidence interval (CI) 1.31–1.93 per SD-increase), body mass index (BMI, OR 1.33, 95% CI 1.23–1.43 per SD-increase), waist circumference (OR 1.82; 95% CI 1.48–2.24 per SD-increase), type 2 diabetes (OR 1.21, 95% CI 1.15–1.27 per unit increase in log-transformed odds), systolic blood pressure (OR 1.17; 95% CI 1.07–1.26 per 10 mmHg increase), high-density lipoprotein cholesterol (OR 0.84, 95% CI 0.77–0.90 per SD-increase), and triglycerides (OR 1.23, 95% CI 1.15–1.33 per SD-increase). The associations for type 2 diabetes, systolic blood pressure, triglycerides, but not for high-density lipoprotein cholesterol remained strong after adjusting for genetically-predicted BMI. Genetic liability to type 2 diabetes mediated 51.4% (95% CI 13.4–89.3%) of the BMI-effects on NAFLD risk. There were suggestive inverse associations of genetically-predicted alcohol, coffee, and caffeine consumption, and vigorous physical activity with NAFLD risk. This study identified several lifestyle and metabolic factors that may be causally implicated in NAFLD.

Clinical practice advice on lifestyle modification in the management of nonalcoholic fatty liver disease in Japan: an expert review

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver diseases worldwide, including in Japan. The Japanese Society of Gastroenterology (JSGE) and the Japanese Society of Hepatology (JSH) have established the Japanese NAFLD/NASH guidelines in 2014 and revised these guidelines in 2020. As described in these guidelines, weight reduction by diet and/or exercise therapy is important for the treatment of NAFLD patients. The I148M single nucleotide polymorphism (rs738409 C > G) of PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is widely known to be associated with the occurrence and progression of NAFLD. In the Japanese, the ratio of PNPLA3 gene polymorphisms found is approximately 20%, which is higher than that found in Westerners. In addition, the ratio of lean NAFLD patients is also higher in Japan than in Western countries. Therefore, the method for lifestyle guidance for the NAFLD patients in Japan would be different from that for the people in Western countries. The problems in the treatment of NAFLD patients include alcohol consumption and sarcopenia. Therefore, guidelines that can help clinicians treat Japanese patients with NAFLD are needed. In this expert review, we summarize evidence-based interventions for lifestyle modification (diet, exercise, alcohol, and sarcopenia) for the treatment of patients with NAFLD, especially from Japan and Asian countries.

Alcohol and Metabolic-associated Fatty Liver Disease

The diagnosis of metabolic-associated fatty liver disease is based on the detection of liver steatosis together with the presence of metabolic dysfunction. According to this new definition, the diagnosis of metabolic-associated fatty liver disease is independent of the amount of alcohol consumed. Actually, alcohol and its metabolites have various effects on metabolic-associated abnormalities during the process of alcohol metabolism. Studies have shown improved metabolic function in light to moderate alcohol drinkers. There are several studies focusing on the role of light to moderate alcohol intake on metabolic dysfunction. However, the results from studies are diverse, and the conclusions are often controversial. This review systematically discusses the effects of alcohol consumption, focusing on light to moderate alcohol consumption, obesity, lipid and glucose metabolism, and blood pressure.

Diet and exercise in NAFLD/NASH: Beyond the obvious

Lifestyle represents the most relevant factor for non-alcoholic fatty liver disease (NAFLD) as the hepatic manifestation of the metabolic syndrome. Although a tremendous body of clinical and preclinical data on the effectiveness of dietary and lifestyle interventions exist, the complexity of this topic makes firm and evidence-based clinical recommendations for nutrition and exercise in NAFLD difficult. The aim of this review is to guide readers through the labyrinth of recent scientific findings on diet and exercise in NAFLD and non-alcoholic steatohepatitis (NASH), summarizing "obvious" findings in a holistic manner and simultaneously highlighting stimulating aspects of clinical and translational research "beyond the obvious". Specifically, the importance of calorie restriction regardless of dietary composition and evidence from low-carbohydrate diets to target the incidence and severity of NAFLD are discussed. The aspect of ketogenesis-potentially achieved via intermittent calorie restriction-seems to be a central aspect of these diets warranting further investigation. Interactions of diet and exercise with the gut microbiota and the individual genetic background need to be comprehensively understood in order to develop personalized dietary concepts and exercise strategies for patients with NAFLD/NASH.

The Effects of Modest Alcohol Consumption on Non-alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

Background and Objective: There is no consensus regarding modest alcohol consumption in patients with non-alcoholic fatty liver disease (NAFLD) due to conflicting results. The aim of this meta-analysis was to examine the effects of modest alcohol consumption on histological severity, histological course, hepatocellular carcinoma, and long-term clinical outcomes in NAFLD patients.

Methods: We searched MEDLINE and EMBASE databases from inception to October 2020 for studies evaluating the effects of modest alcohol consumption among patients with NAFLD. A random-effects meta-analysis using pooled odds ratio (OR) and hazard ratio (HR) was calculated with 95% confidence interval (CI). Study quality was assessed with the Newcastle-Ottawa Scale.

Results: Fourteen cross-sectional or cohort studies with aggregate data on 14,435 patients were included in the analysis. Modest alcohol consumption resulted in lower risks for steatohepatitis (OR 0.59; 95% CI 0.45–0.78; I² = 12%) and advanced fibrosis (OR 0.59, 95% CI 0.36–0.95; I² = 75%). Histological follow-up data showed that modest alcohol use was associated significantly with less steatohepatitis resolution but not with fibrosis progression. The HR for developing hepatocellular carcinoma was 3.77 (95% CI 1.75–8.15; I² = 0%). NAFLD patients with modest alcohol intake had a lower mortality risk than lifelong abstainers (HR 0.85; 95% CI 0.75–0.95; I² = 64%).

Conclusion: This meta-analysis suggests that medical advice for modest alcohol drinking should be made cautiously in caring for an individual patient based on the clinical context. Practically, patients with steatohepatitis or advanced fibrosis should avoid alcohol use, whereas patients with low fibrosis risk may be allowed for modest and safe drinking.

Associations between alcohol consumption and hepatic steatosis in the USA

Despite being widely recognized as a common cause of fatty liver, the exact impact of alcohol consumption on hepatic steatosis in the general population is elusive. The recent National Health and Nutrition Examination Survey (NHANES) allowed us to examine this relationship among US adults. Herein, we extracted data on detailed alcohol consumption and controlled attenuation parameter (CAP) by FibroScan from 4509 participants in NHANES 2017-2018. Compared to metabolic risk factors such as diabetes and obesity, the association between alcohol consumption and CAP was less significant. In multivariable analysis, only those drinking 5-7 times per week showed significant increases in CAP scores. Although both frequency and quantity of drinking were positively associated with CAP score, only frequency remained significant after adjustment for quantity and binge drinking. These epidemiological observations suggested that the impact of alcohol on hepatic steatosis was much smaller than metabolic factors and dependent upon the frequency of drinking.

The FibroScan-aspartate aminotransferase score can stratify the disease severity in a Japanese cohort with fatty liver diseases

This study aimed to prove that the FibroScan-aspartate aminotransferase (FAST) scores can be used to stratify disease severity in a Japanese cohort with fatty liver diseases [metabolic dysfunction-associated fatty liver disease (MAFLD) and nonalcoholic fatty liver disease (NAFLD)]. All the participants (n = 2254) underwent liver stiffness measurements and controlled attenuation parameter assessments. We compared the clinical characteristics of the patients with MAFLD and NAFLD using the FAST scores and explored the independent determinants of FAST scores ≥ 0.35, which indicated possible progressive disease. Overall, MAFLD was diagnosed in 789 patients (35.0%), while NAFLD was diagnosed in 618 (27.4%). The proportion of patients that had a condition that suggested progressive liver disease was higher in those with MAFLD than in those with NAFLD [68 (8.6%) vs 48 (7.7%)]. The area under the receiver-operating characteristic curve of the FAST score for diagnosing advanced fibrosis was 0.969 in MAFLD and 0.965 in NAFLD. Multivariate analyses determined that diabetes mellitus, alanine aminotransferase (ALT) levels, fatty liver index, and Fibrosis-4 index independently predict FAST scores ≥ 0.35 in patients with MAFLD. ALT levels had the strongest correlation with the FAST scores (p = 0.7817). The FAST score could stratify the disease severity in the Japanese cohort with fatty liver diseases.

Validation of a two-step approach combining serum biomarkers and liver stiffness measurement to predict advanced fibrosis

Background and Aim

The Gut and Obesity in Asia Workgroup recently reported that a two‐step approach using fibrosis scores followed by liver stiffness measurement (LSM) could accurately detect patients with non‐alcoholic fatty liver disease (NAFLD) having advanced fibrosis in low‐risk fibrosis populations. This study aimed to validate the utility of this approach using a Japanese health checkup registry.

Methods

This cross‐sectional study included subjects who underwent a health checkup from 2014 to 2019. Using estimated fibrosis stage measured by LSM as a standard, we calculated the percentage of misclassification from assessments made based on fibrosis scores (NAFLD fibrosis score [NFS] or Fibrosis‐4 score [FIB‐4]) and LSM, alone or in combination.

Results

Of 630 subjects with NAFLD, 4 (0.8%) had advanced fibrosis. In the first‐step evaluation, only 21.4–38.0% of subjects needed further testing. This approach was associated with a high specificity of approximately 100% and a negative predictive value of 99.7%. The percentage of misclassification based on NFS or FIB‐4 values followed by LSM in all subjects and using LSM after NFS or FIB‐4 determination only in subjects with indeterminate/high NFS or FIB‐4 values (two‐step approach) was 0% and 0.3% and 0.16% and 0.3%, respectively. In addition, very few false negatives occurred for both NFS and FIB‐4.

Conclusion

The two‐step approach helps to identify the subjects with NAFLD who have advanced fibrosis during a routine health checkup and is associated with only a few false negatives.

Alcohol consumption in patients with nonalcoholic fatty liver disease: yes, or no?

Excessive alcohol intake is an established risk factor for chronic liver disease. At the same time, moderate alcohol intake appears to reduce cardiovascular morbidity. Accordingly, recommendations for alcohol intake in patients with nonalcoholic fatty liver disease (NAFLD), who are at increased risk for liver-related and cardiovascular events, are a point of debate. Some studies have shown beneficial effects of alcohol on cardiovascular and overall mortality in this specific subset of patients. Nonetheless, even light alcohol intake appears to aggravate liver disease and increase the risk of hepatocellular cancer. Therefore, patients with nonalcoholic steatohepatitis or advanced fibrosis should be advised against consuming alcohol. On the other hand, only light alcohol consumption (<10 g/day) might be permitted in patients without significant hepatic fibrosis, provided that they are carefully followed-up. As the research field focusing on NAFLD keeps widening, more prospective studies regarding this specific subject are expected, and may provide a basis for less ambiguous recommendations.

Alcohol consumption in the general population is associated with structural changes in multiple organ systems

Background:

Excessive alcohol consumption is associated with damage to various organs, but its multi-organ effects have not been characterised across the usual range of alcohol drinking in a large general population sample.

Methods:

We assessed global effect sizes of alcohol consumption on quantitative magnetic resonance imaging phenotypic measures of the brain, heart, aorta, and liver of UK Biobank participants who reported drinking alcohol.

Results:

We found a monotonic association of higher alcohol consumption with lower normalised brain volume across the range of alcohol intakes (–1.7 × 10⁻³ ± 0.76 × 10⁻³ per doubling of alcohol consumption, p=3.0 × 10⁻¹⁴). Alcohol consumption was also associated directly with measures of left ventricular mass index and left ventricular and atrial volume indices. Liver fat increased by a mean of 0.15% per doubling of alcohol consumption.

Conclusions:

Our results imply that there is not a ‘safe threshold’ below which there are no toxic effects of alcohol. Current public health guidelines concerning alcohol consumption may need to be revisited.

Funding:

See acknowledgements.

Moderate alcohol consumption is associated with advanced fibrosis in non-alcoholic fatty liver disease and shows a synergistic effect with type 2 diabetes mellitus

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Whether moderate alcohol consumption plays a role for progression of NAFLD is disputed. Moreover, it is not known which tool is ideal for assessment of alcohol consumption in NAFLD. This study aimed to evaluate if moderate alcohol consumption assessed with different methods, including the biological marker phosphatidylethanol (PEth), is associated with advanced fibrosis in NAFLD.

METHODS

We conducted a cross-sectional study of patients with biopsy-proven NAFLD. All participants were clinically evaluated with medical history, blood tests, and anthropometric measurements. Alcohol consumption was assessed using PEth in blood, the questionnaire AUDIT-C, and clinical interview.

FINDINGS

86 patients were included of which 17% had advanced fibrosis. All participants reported alcohol consumption < 140 g/week. Average weekly alcohol consumption was higher in the group with advanced fibrosis. Moderate alcohol consumption, independently of the method of assessment, was associated with increased probability of advanced fibrosis (adjusted OR 5.5-9.7, 95% CI 1.05-69.6). Patients with type 2 diabetes mellitus (T2DM) consuming moderate amounts of alcohol had a significantly higher rate of advanced fibrosis compared with those consuming low amounts (50.0-60.0% vs. 3.3-21.6%, p < 0.05).

CONCLUSIONS

Moderate alcohol consumption, irrespective of assessment method (clinical interview, AUDIT-C, and PEth), was associated with advanced fibrosis. PEth in blood ≥ 50 ng/mL may be a biological marker indicating increased risk for advanced fibrosis in NAFLD. Patients with T2DM consuming moderate amounts of alcohol had the highest risk of advanced fibrosis, indicating a synergistic effect of insulin resistance and alcohol on the histopathological progression of NAFLD.

Second hits exacerbate alcohol-related organ damage: an update

Chronic and excessive alcohol abuse cause direct and indirect detrimental effects on a wide range of body organs and systems and accounts for ~4% of deaths worldwide. Many factors influence the harmful effects of alcohol. This concise review presents newer insights into the role of select second hits in influencing the progression of alcohol-induced organ damage by synergistically acting to generate a more dramatic downstream biological defect. This review specifically addresses on how a lifestyle factor of high fat intake exacerbates alcoholic liver injury and its progression. This review also provides the mechanistic insights into how increasing matrix stiffness during liver injury promotes alcohol-induced fibrogenesis. It also discusses how hepatotropic viral (HCV, HBV) infections as well as HIV (which is traditionally not known to be hepatotropic), are potentiated by alcohol exposure to promote hepatotoxicity and fibrosis progression. Finally, this review highlights the impact of reactive aldehydes generated during alcohol and cigarette smoke coexposure impair innate antimicrobial defense and increased susceptibility to infections. This review was inspired by the symposium held at the 17th Congress of the European Society for Biomedical research on Alcoholism in Lille, France entitled 'Second hits in alcohol-related organ damage'.

[Mixed steatohepatitis: more questions than answers (Part 1)]

The term steatohepatitis is used for a heterogeneous group of diseases of various etiologies, characterized by a similar morphological picture. Earlier the diagnosis of non-alcoholic fatty liver disease implied the exclusion of other causes of steatohepatitis, in recent years it has been suggested that a combination of various etiological variants of steatohepatitis is possible. The review considers the terminological, epidemiological and pathogenetic aspects of the most common combination: metabolic and alcoholic genesis, the issues of the mutual influence of etiopathogenetic factors and the identification of the predominant process. Issues of existing and prospective pathogenetic and symptomatic therapy are discussed in detail. Treatment of steatohepatitis is based on the elimination of known causal factors and lifestyle modification; therapy includes medications, that have been proven to be effective in certain types of steatohepatitis and symptomatic therapy as well.

A Cohort Study Examining the Interaction of Alcohol Consumption and Obesity in Hepatic Steatosis and Mortality

OBJECTIVE

To study the interaction of alcohol consumption with body mass index (BMI) in the development of hepatic steatosis and mortality.

PARTICIPANTS AND METHODS

We conducted a retrospective cohort study of 18,506 participants without fatty liver disease or cirrhosis at enrollment in the Mayo Clinic Biobank from April 9, 2009, through March 31, 2016. Participants were classified by self-reported alcohol consumption status (nondrinkers, moderate drinkers [0 to 2 drinks per day], and heavy drinkers [>2 drinks per day]). The primary outcome of interest was the incidence of hepatic steatosis, identified by International Classification of Diseases, Ninth Revision code and confirmed with imaging. The secondary outcome of interest was all-cause mortality. Multivariate Cox regression analysis determined the impact of alcohol consumption stratified by BMI on outcomes compared with nondrinkers.

RESULTS

The cohort (mean ± SD age, 55.8±16.9 years; 63.8% female; mean ± SD BMI, 28.8±6.1 kg/m²) of 18,506 participants included 3657 (19.8%) nondrinkers, 14,236 (76.9%) moderate drinkers, and 613 (3.3%) heavy drinkers at enrollment. After a median follow-up of 5.8 years (interquartile range, 3.8 to 7.2 years), 684 participants had development of hepatic steatosis and 968 died. In moderate drinkers, the risk of hepatic steatosis development was high in the obese group (adjusted hazard ratio [AHR], 1.31; 95% CI, 1.03 to 1.67), insignificant in the overweight group (AHR, 0.86; 95% CI, 0.58 to 1.26), and decreased in the normal-BMI group (AHR, 0.48; 95% CI, 0.26 to 0.90). Heavy drinkers had an increased risk of hepatic steatosis irrespective of BMI. Moderate alcohol use was associated with decreased mortality in the normal-weight (AHR, 0.44; 95% CI, 0.34 to 0.58) and overweight (AHR, 0.70; 95% CI, 0.56 to 0.88) groups but not in the obese group (AHR, 0.80; 95% CI, 0.64 to 1.00).

CONCLUSION

In obese individuals, even moderate alcohol use is associated with the development of hepatic steatosis. Moderate alcohol consumption is associated with lower mortality in normal-BMI and overweight individuals but not in those who are obese.

Established and emerging factors affecting the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease affecting approximately 25% of the global population. Although a majority of NAFLD patients will never experience liver-related symptoms it is estimated that 5-10% will develop cirrhosis-related complications with risk of death or need for liver transplantation. NAFLD is closely associated with cardiovascular disease and components of the metabolic syndrome. However, NAFLD is not uncommon in lean individuals and may in these subjects represent a different entity with separate pathophysiological mechanisms involved implying a higher risk for development of end-stage liver disease. There is considerable fluctuation in the histopathological course of NAFLD that may partly be attributed to lifestyle factors and dietary composition. Nutrients such as fructose, monounsaturated fatty acids, and trans-fatty acids may aggravate NAFLD. Presence of type 2 diabetes mellitus seems to be the most important clinical predictor of liver-related morbidity and mortality in NAFLD. Apart from severity of the metabolic syndrome, genetic polymorphisms and environmental factors, such as moderate alcohol consumption, may explain the variation in histopathological and clinical outcome among NAFLD patients.

The effect of moderate alcohol drinking in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is defined by fat accumulation in liver that is not caused by excessive alcohol consumption. Safe limits of alcohol consumption in NAFLD are usually defined as alcohol consumption of less than 210 g per week for men and 140 g per week for women (30 g/day in men, 20 g/day in women) and alcohol consumption below safe limits is generally regarded as moderate alcohol consumption. Many studies have investigated the effects of moderate alcohol consumption on NAFLD patients. Some studies showed that moderate alcohol consumption prevented the progression of fibrosis in the liver, whereas other reports showed worsening of fibrosis in the liver based on serologic, radiologic and liver biopsy findings compared with effects on total abstainers. NAFLD is also thought to be a hepatic manifestation of metabolic syndrome, and when combined with excessive alcohol consumption results in the development of components of metabolic syndrome and systemic harmful effects. The effects of moderate alcohol consumption on NAFLD have yet to be established.

Obesity and binge alcohol intake are deadly combination to induce steatohepatitis: A model of high-fat diet and binge ethanol intake

Obesity and binge drinking often coexist and work synergistically to promote steatohepatitis; however, the underlying mechanisms remain obscure. In this mini-review, we briefly summarize clinical evidence of the synergistical effect of obesity and heavy drinking on steatohepatitis and discuss the underlying mechanisms obtained from the study of several mouse models. High-fat diet (HFD) feeding and binge ethanol synergistically induced steatohepatitis and fibrosis in mice with significant intrahepatic neutrophil infiltration; such HFD-plus-ethanol treatment markedly up-regulated the hepatic expression of many chemokines with the highest fold (approximately 30-fold) induction of chemokine (C-X-C motif) ligand 1 (Cxcl1), which contributes to hepatic neutrophil infiltration and liver injury. Furthermore, HFD feeding activated peroxisome proliferator-activated receptor gamma that subsequently inhibited CXCL1 upregulation in hepatocytes, thereby forming a negative feedback loop to prevent neutrophil overaction; whereas binge ethanol blocked this loop and then exacerbated CXCL1 elevation, neutrophil infiltration, and liver injury. Interestingly, inflamed mouse hepatocytes attracted neutrophils less effectively than inflamed human hepatocytes due to the lower induction of CXCL1 and the lack of the interleukin (IL)-8 gene in the mouse genome, which may be one of the reasons for difficulty in development of mouse models of alcoholic steatohepatitis and nonalcoholic steatohepatitis (NASH). Hepatic overexpression of Cxcl1 and/or IL-8 promoted steatosis-to-NASH progression in HFD-fed mice by inducing neutrophil infiltration, oxidative stress, hepatocyte death, fibrosis, and p38 mitogen-activated protein kinase activation. Collectively, obesity and binge drinking synergistically promote steatohepatitis via the induction of CXCL1 and subsequent hepatic neutrophil infiltration.

Effects of low ethanol consumption on nonalcoholic steatohepatitis in mice

Several recent clinical and epidemiological studies have suggested inhibitory effects of light-to-moderate alcohol consumption on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH); however, these effects have not been confirmed in experimental studies. Therefore, in this study, we examined the effects of small amounts of ethanol consumption on a mouse model of NASH. Nine-week-old male obese mice (db/db mice) were divided into the following groups: control, high-fat, and low-ethanol groups. The control group was provided ad libitum access to a control liquid diet, the high-fat group was provided access to a high-fat liquid diet, and the low-ethanol group was provided access to the high-fat liquid diet supplemented with 0.1% (w/w) ethanol. Eight weeks later, the mice were sacrificed and serum biochemical, histopathological, and molecular analyses were performed. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were significantly lower in the low-ethanol group than in the high-fat group (p = 0.033 and 0.037, respectively). Liver histopathological analysis showed that intralobular and portal inflammation was significantly milder in the low-ethanol group than in the high-fat group (p = 0.018 and 0.041, respectively). However, no significant differences were observed among the groups in serum insulin and adiponectin levels, hepatic 4-hydroxynonenal (oxidative injury marker) levels, and hepatic cytokine and receptor gene expression levels. In conclusion, the serum transaminase levels and hepatic inflammation in NASH model mice improved after administration of small amounts of ethanol. This study directly demonstrated inhibitory effects of small amounts of ethanol on NASH in mice. The mechanisms underlying these inhibitory effects remain to be elucidated.

Effect of alcohol consumption and the presence of fatty liver on the risk for incident type 2 diabetes: a population-based longitudinal study

INTRODUCTION

Both fatty liver disease (FLD) and alcohol consumption have been reported to affect incident type 2 diabetes mellitus. The aim of this study was to evaluate the combined effect of FLD and alcohol consumption on incident type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this historical cohort study involving 9948 men, we investigated the influence of the presence of FLD and the grades of alcohol consumption on incident type 2 diabetes using Cox proportional hazards models. We categorized the participants into the following four groups: none or minimal alcohol consumption, <40 g/week; light, 40-140 g/week; moderate, 140-280 g/week; or heavy alcohol consumption, >280 g/week. FLD was diagnosed by abdominal ultrasonography.

RESULTS

During the median 6.0-year follow-up, 568 participants developed type 2 diabetes. Heavy alcohol consumers with FLD showed a higher risk for developing type 2 diabetes compared with the other groups. Moderate alcohol consumers without FLD had a significantly higher risk for developing incident type 2 diabetes, compared with none or minimal and light alcohol consumers without FLD. In contrast, there was no apparent difference in the risk for incident type 2 diabetes between none or minimal, light, and moderate alcohol consumers with FLD. Furthermore, there was no statistically significant difference in the risk for incident type 2 diabetes between a moderate and heavy alcohol consumer without FLD and a none or minimal, light, and moderate alcohol consumer with FLD.

CONCLUSIONS

To prevent incident type 2 diabetes, we should acknowledge that the impact of alcohol consumption may vary in the presence of FLD.

Non-alcoholic Fatty Liver Disease and Alcohol-Related Liver Disease: Two Intertwined Entities

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, with a prevalence of 25-30%. Since its first description in 1980, NAFLD has been conceived as a different entity from alcohol-related fatty liver disease (ALD), despite that, both diseases have an overlap in the pathophysiology, share genetic-epigenetic factors, and frequently coexist. Both entities are characterized by a broad spectrum of histological features ranging from isolated steatosis to steatohepatitis and cirrhosis. Distinction between NAFLD and ALD is based on the amount of consumed alcohol, which has been arbitrarily established. In this context, a proposal of positive criteria for NAFLD diagnosis not considering exclusion of alcohol consumption as a prerequisite criterion for diagnosis had emerged, recognizing the possibility of a dual etiology of fatty liver in some individuals. The impact of moderate alcohol use on the severity of NAFLD is ill-defined. Some studies suggest protective effects in moderate doses, but current evidence shows that there is no safe threshold for alcohol consumption for NAFLD. In fact, given the synergistic effect between alcohol consumption, obesity, and metabolic dysfunction, it is likely that alcohol use serves as a significant risk factor for the progression of liver disease in NAFLD and metabolic syndrome. This also affects the incidence of hepatocellular carcinoma. In this review, we summarize the overlapping pathophysiology of NAFLD and ALD, the current data on alcohol consumption in patients with NAFLD, and the effects of metabolic dysfunction and overweight in ALD.

Low Levels of Alcohol Consumption, Obesity, and Development of Fatty Liver With and Without Evidence of Advanced Fibrosis

BACKGROUND AND AIMS

The effects of low-level alcohol consumption on fatty liver disease and the potential for effect modification by obesity is uncertain. We investigated associations among low-level alcohol consumption, obesity status, and the development of incident hepatic steatosis (HS), either with or without an increase in noninvasive liver fibrosis score category (from low to intermediate or high category).

APPROACH AND RESULTS

A total of 190,048 adults without HS and a low probability of fibrosis with alcohol consumption less than 30 g/day (men) and less than 20 g/day (women) were followed for up to 15.7 years. Alcohol categories of no, light, and moderate consumption were defined as 0, 1-9.9, and 10-29.9 g/day (10-19.9 g/day for women), respectively. HS was diagnosed by ultrasonography, and the probability of fibrosis was estimated using the fibrosis-4 index (FIB-4). Parametric proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). A total of 43,466 participants developed HS, 2,983 of whom developed HS with an increase in FIB-4 index (to intermediate or high scores). Comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for incident HS were 0.93 (0.90-0.95) and 0.90 (0.87-0.92), respectively. In contrast, comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for developing HS plus intermediate/high FIB-4 were 1.15 (1.04-1.27) and 1.49 (1.33-1.66), respectively. The association between alcohol consumption categories and incident HS plus intermediate/high FIB-4 was observed in both nonobese and obese individuals, although the association was stronger in nonobese individuals (P for interaction by obesity = 0.017).

CONCLUSIONS

Light/moderate alcohol consumption has differential effects on the development of different stages of fatty liver disease, which is modified by the presence of obesity.

Obstacles and opportunities in the prevention and treatment of HBV-related hepatocellular carcinoma

Despite the tremendous progresses toward our understanding of the mechanisms of how liver cancer was developed, the therapeutic outcomes of liver cancer in the clinic have very limited improvement within the past three decades or so. In addition, both the incidence and mortality of liver cancer worldwide are not dropping, but increasing steadily, in the last decade. Thus, it is time for us to rethink what has been wrong and how could we do better in the upcoming years, in order to achieve our goal of improving the therapeutic outcomes of patients with liver cancer in the clinic, and at the meantime, effectively reducing the incidence of liver cancer by blocking malignant transformation of hepatocytes from chronic viral infection. This is also one of the main reasons why we try to organize this special issue on primary liver cancer in the journal of Genes & Diseases. In this perspective, I will summarize the major obstacles confronted with in the prevention and management of patients with chronic hepatitis B infection and subsequent development of liver cirrhosis and liver cancer. Next, I will delineate the pitfalls and underlying mechanisms of why the current anti-viral strategies and therapeutic agents are not as effective as one expected in terms of successful reduction or prevention chronic hepatitis B infection associated liver cirrhosis and liver cancer. I will then provide my personal perspectives on potential approaches and strategies for effective prevention and management of hepatitis B-related liver cancer.

Moderate Alcohol Intake in Non-Alcoholic Fatty Liver Disease: To Drink or Not to Drink?

Nonalcoholic fatty liver disease (NAFLD) is defined by hepatic steatosis in the presence of alcohol intake within safe limits, defined by guidelines of scientific associations (usually 20 g or 2 units/day in women, 30 g or 3 units in men). The diagnosis is usually followed by medical counseling of total abstinence, in order to prevent disease progression. This policy has been challenged by epidemiological studies, suggesting that the risk of liver disease and disease progression is lower in modest drinkers than in total abstainers. We revised the literature on the effects of modest alcohol intake on disease burden. Epidemiological data may suffer from several potential biases (recall bias for retrospective analyses, difficulties in the calculation of g/day), limiting their validity. Prospective data suggest that NAFLD patients with regular alcohol intake, although within the safe thresholds, are at higher risk of liver disease progression, including hepatocellular carcinoma; a detrimental effect of modest alcohol drinking is similarly observed in liver disease of viral etiology. Alcohol intake is also a risk factor for extrahepatic cancers, particularly breast, oral, and pharyngeal cancers, with gender difference and no floor effect, which outweigh the possible beneficial effects on cardiovascular system, also derived from retrospective studies. Finally, the negative effects of the calorie content of alcohol on dietary restriction and weight loss, the pivotal intervention to reduce NAFLD burden, should be considered. In summary, the policy of counseling NAFLD patients for alcohol abstinence should be maintained.

Effect of alcohol consumption on nonalcoholic fatty liver disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) is estimated to be 26.3% among the US population. A subset of this population exhibits an aggressive histological phenotype, nonalcoholic steatohepatitis (NASH) with ≥ stage 2 fibrosis, which may progress to cirrhosis. The definition of NAFLD excludes excessive alcohol intake, which is well known to cause alcoholic liver disease and will not be discussed here. Most NAFLD clinical trials use ~14 drinks per week as the cutoff for excessive alcohol intake. Alcohol consumption below this threshold, which we define as moderate alcohol consumption, is common in the US. According to the 2012 Behavioral Risk Factor Surveillance System (BRFSS), 56% of the US adult population consume alcohol, but only 8.2% report drinking heavily and 18.3% report binge drinking. The American Association for the Study of Liver Diseases (AASLD) Practice Guidance of 2018 states that there are insufficient data to make a recommendation with regard to moderate alcohol consumption in patients with NAFLD, citing a lack of longitudinal studies that examine the impact of moderate alcohol consumption on disease progression and its extrahepatic harms versus benefits, specifically in individuals with established NAFLD. NAFLD prevalence studies have generally noted a negative correlation between modest alcohol consumption and NAFLD. However, prevalence studies have limited application to patients with established NAFLD who present to the clinic. There can also be many confounding factors, because modest alcohol consumption is also negatively associated with some NAFLD risk factors, and those risk factors may not be adequately adjusted for in analyses. The prevalence of NASH with significant fibrosis (≥ F2) is more important because this is the group that is believed to have progressive disease. Thus, cohort studies of disease progression are more important from the patient's standpoint. Because these patients have already developed NAFLD or NASH, their interest lies in their odds of disease progression if they have moderate alcohol consumption compared to abstinence. It is also noteworthy that cardiovascular disease is the most important cause of death among patients with NAFLD. Moderate alcohol consumption has been associated with a reduction in overall mortality, but mostly in cardiovascular mortality. However, this protective effect has not been demonstrated specifically in patients with NAFLD.