NAFLD vs. MAFLD - It is not the name but the disease that decides the outcome in fatty liver

Metabolic dysfunction-associated fatty liver disease indicates more hepatic fibrosis than nonalcoholic fatty liver disease

The term metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed based on a redefinition of the nonalcoholic fatty liver disease (NAFLD) criteria. Our study aimed to address the knowledge gap by comparing the diagnostic accuracy of MAFLD and NAFLD criteria in identifying significant fibrosis among patients with hepatic steatosis. A cross-sectional study was conducted on 2626 patients with hepatic steatosis treated at Beijing Ditan Hospital between January 2009 and December 2022. Patients with viral hepatitis were excluded. Significant fibrosis was defined as a Meta-analysis of Histological Data in Viral Hepatitis (METAVIR) score F ≥ 2. MAFLD and NAFLD were diagnosed in 478 and 428 patients, respectively. Clinicopathological characteristics were compared between the MAFLD+ NAFLD- group (patients who met the criteria for MAFLD but not NAFLD) and MAFLD- NAFLD+ group (patients who met the criteria for NAFLD but not MAFLD). A total of 743 patients with histologically verified hepatic steatosis were analyzed. The MAFLD+ NAFLD- group comprised 163 (21.9%) and the MAFLD- NAFLD+ group comprised 113 (15.2%) patients. Patients in the MAFLD+ NAFLD- group were older and more likely to be male and had higher body mass index and liver stiffness levels than those in the MAFLD- NAFLD+ group. The prevalence of significant fibrosis was higher in the MAFLD+ NAFLD- group than in the MAFLD- NAFLD+ group (43.6% vs 15.9%, P < .001). The MAFLD criteria may be a better indicator of fibrosis than the NAFLD criteria. Fibrosis in patients with MAFLD can be determined by metabolic disorders, not excessive alcohol consumption.

Impact of nomenclature as metabolic associated steatotic liver disease on steatotic liver disease prevalence and screening: a prospective population survey in Asians

BACKGROUND AND AIM

The introduction of the latest nomenclature, metabolic associated steatotic liver disease (MASLD), proposed by the multi-society without Asian society consensus statement, aims to redefine the diagnostic criteria for metabolic associated fatty liver disease (MAFLD). However, its effect on the epidemiology in Asia remains unclear.

METHOD

We conducted a population-based cross-sectional survey on fatty liver disease using multistage stratified random sampling of participants from Guangzhou, a representative area in China (ChiCTR2000033376). Demographic, socioeconomic, lifestyle, and laboratory data were collected. Hepatic steatosis and the severity of fibrosis were assessed using FibroScan.

RESULTS

A total of 7388 individuals were recruited, the proportion of which meeting the definitions for nonalcoholic fatty liver disease (NAFLD), MAFLD, and MASLD were 2359 (31.9%), 2666 (36.1%), and 2240 (30.3%), respectively. One hundred and twenty (1.6%) patients had cryptogenic SLD, and 537 (7.3%) patients were diagnosed with MetALD. MASLD did not significantly differ from NAFLD and MAFLD, except that MAFLD patients had a lower proportion of males, hypertension, and diabetes and were less likely to consume tea (P < 0.05). Both cryptogenic SLD and MASLD non-MAFLD patients exhibited milder hepatic steatosis and a lower frequency of liver injury than NAFLD, MAFLD, or MASLD patients (all P < 0.05). An increased HOMA-IR (adjusted OR: 1.33, 95% CI: 1.10-2.03) was associated with higher risk of moderate-to-severe steatosis for MASLD non-MAFLD patients, while consuming more cups of tea (P for trend = 0.015) showed inverse associations.

CONCLUSION

Irrespective of terminology used is that fatty liver disease is highly prevalent in the Han Chinese population. Differences in insulin resistance and lifestyle risk factors are associated with redefinition disparities.

Association of MAFLD and MASLD with all-cause and cause-specific dementia: a prospective cohort study

BACKGROUND

Liver disease and dementia are both highly prevalent and share common pathological mechanisms. We aimed to investigate the associations between metabolic dysfunction-associated fatty liver disease (MAFLD), metabolic dysfunction-associated steatotic liver disease (MASLD) and the risk of all-cause and cause-specific dementia.

METHODS

We conducted a prospective study with 403,506 participants from the UK Biobank. Outcomes included all-cause dementia, Alzheimer's disease, and vascular dementia. Multivariable Cox proportional hazards models were used for analyses.

RESULTS

155,068 (38.4%) participants had MAFLD, and 111,938 (27.7%) had MASLD at baseline. During a median follow-up of 13.7 years, 5,732 participants developed dementia (2,355 Alzheimer's disease and 1,274 vascular dementia). MAFLD was associated with an increased risk of vascular dementia (HR 1.32 [95% CI 1.18-1.48]) but a reduced risk of Alzheimer's disease (0.92 [0.84-1.0]). Differing risks emerged among MAFLD subtypes, with the diabetes subtype increasing risk of all-cause dementia (1.8 [1.65-1.96]), vascular dementia (2.95 [2.53-3.45]) and Alzheimer's disease (1.46 [1.26-1.69]), the lean metabolic disorder subtype only increasing vascular dementia risk (2.01 [1.25-3.22]), whereas the overweight/obesity subtype decreasing risk of Alzheimer's disease (0.83 [0.75-0.91]) and all-cause dementia (0.9 [0.84-0.95]). MASLD was associated with an increased risk of vascular dementia (1.24 [1.1-1.39]) but not Alzheimer's disease (1.0 [0.91-1.09]). The effect of MAFLD on vascular dementia was consistent regardless of MASLD presence, whereas associations with Alzheimer's disease were only present in those without MASLD (0.78 [0.67-0.91]).

CONCLUSIONS

MAFLD and MASLD are associated with an increased risk of vascular dementia, with subtype-specific variations observed in dementia risks. Further research is needed to refine MAFLD and SLD subtyping and explore the underlying mechanisms contributing to dementia risk.

Impact of metabolic phenotype and alcohol consumption on mortality risk in metabolic dysfunction-associated fatty liver disease: a population-based cohort study

Patients with metabolic dysfunction-associated fatty liver disease (MAFLD) often present with concomitant metabolic dysregulation and alcohol consumption, potentially leading to distinct clinical outcomes. We analyzed data from 8043 participants with MAFLD in the Thai National Health Examination Survey with linked mortality records. According to the MAFLD criteria, 1432 individuals (17.2%) were categorized as having the diabetes phenotype, 5894 (71.0%) as the overweight/obesity phenotype, and 978 (11.8%) as the lean metabolic phenotype. Over 71,145 person-years, 916 participants died. Using Cox proportional hazard models adjusting for physiological, lifestyle, and comorbid factors, both diabetes (adjusted hazards ratio [aHR] 1.59, 95% CI 1.18-2.13) and lean metabolic phenotypes (aHR 1.28, 95% CI 1.01-1.64) exhibited significantly higher mortality risk compared to the overweight/obesity phenotype. A J-shaped relationship was observed between daily alcohol consumption and the risk of all-cause mortality. Daily alcohol intake exceeding 50 g for women and 60 g for men increased the all-cause mortality risk among MAFLD individuals with the lean metabolic phenotype (aHR 3.39, 95% CI 1.02-11.29). Our study found that metabolic phenotype and alcohol consumption have interactive effects on the risk of all-cause mortality in patients with MAFLD, indicating that evaluating both factors is crucial for determining prognostic outcomes and management strategies.

The Global Epidemic of Metabolic Fatty Liver Disease

PURPOSE OF REVIEW

The objective of this manuscript is to examine the current literature on the epidemiology of metabolic dysfunction-associated steatotic liver disease (MASLD), its correlation with cardiovascular disease (CVD) outcomes, as well as to evaluate the update in nomenclature from non-alcoholic liver disease (NAFLD).

RECENT FINDINGS

The update of diagnostic criteria from NAFLD to MASLD reduces the stigma associated with alcohol consumption and poor health choices. It also shines a light on the crucial role of cardiometabolic risk factors in disease pathophysiology. The incidence and prevalence of MASLD are projected to increase significantly in the future as the population burden of cardiometabolic risk factors rises. MASLD is also a potent risk factor for developing CVD that should be tackled by using a multi-disciplinary team with a holistic approach. As the new nomenclature for metabolic liver disease is adopted on a global scale, more research is needed to investigate the applicability of findings from previous trials focusing on NAFLD. It is anticipated that the epidemic of MASLD will continue to increase globally, hence the urgent need for therapeutic approaches to reverse this trend.

Steatotic liver disease predicts cardiovascular disease and advanced liver fibrosis: A community-dwelling cohort study with 20-year follow-up

BACKGROUND

Steatotic liver disease (SLD) has emerged as new nomenclature to increase awareness and reflect the pathophysiology of the disease better. We investigated the risk of advanced fibrosis and cardiovascular disease (CVD) in SLD using data derived from a Korean prospective cohort.

METHODS

We defined SLD using the fatty liver index (FLI) and identified advanced fibrosis with the age-adjusted Fibrosis-4 Index. SLD was further subcategorized into metabolic dysfunction-associated SLD (MASLD), MASLD with increased alcohol intake (MetALD), and alcohol-associated liver disease (ALD).

FINDINGS

The Ansung-Ansan cohort of the Korean Genome and Epidemiology study, following 9497 participants from 2002 to 2020, included 3642 (38.3%) with MASLD, 424 (4.5%) with MetALD, and 207 (2.1%) with ALD. During the median follow-up of 17.5 years, CVD risk was higher in those with MASLD (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.12-1.45; P < 0.001), MetALD (HR, 1.88; 95% CI, 1.33-2.65; P < 0.001), and ALD (HR, 1.95; 95% CI, 1.01-3.77; P < 0.001) than in those without SLD, after adjusting for conventional risk factors. Notably, CVD risk was higher in the MetALD than in the MASLD group (P = 0.027). In the MASLD group, the number of cardiometabolic risk factors (CMRFs) correlated positively with CVD risk (HR, 1.34; 95% CI, 1.24-1.45; P < 0.001 for trend). Among the CMRFs, hypertension (HR, 1.94; 95% CI, 1.63-2.31; P < 0.001) was the predominant contributor to CVD. The MASLD (HR, 1.39; 95% CI, 1.25-1.55; P < 0.001), MetALD (HR, 1.75; 95% CI, 1.38-2.23; P < 0.001), and ALD (HR, 2.00; 95% CI, 1.30-3.07; P = 0.002) groups had a higher risk of advanced fibrosis than did the non-SLD group (P < 0.001 for trend).

INTERPRETATION

Our study provides new insight into hepatic and cardiovascular outcomes related to SLD subtypes. The risk of CVD increased in the order of no SLD, MASLD, and MetALD. The SLD subcategories, considering CMRFs and alcohol intake, outperformed traditional fatty liver categorizations in predicting CVD risk. The proposed SLD terminology could impact clinical practice, warranting further exploration of the heterogeneity of clinical outcomes among SLD subtypes.

The evil relationship between liver fibrosis and cardiovascular disease in metabolic dysfunction-associated fatty liver disease (MAFLD): Looking for the culprit

Metabolic dysfunction-associated fatty liver disease (MAFLD), the hepatic component of the metabolic syndrome caused by insulin resistance, is a major public health problem, affecting about the 25 % of the general population in Western countries. Morbidity and mortality of MAFLD patients is increased primarily due to cardiovascular disease (CVD). Liver fibrosis, the byproduct of hepatic repair, is the main determinant of MAFLD progression and the strongest predictor for overall mortality. Since the mechanistic relationship between MAFLD, fibrosis, insulin resistance and the cardiometabolic risk is far to be clear, deciphering the functional link of hepatic fibrogenesis with genetic factors and hypercoagulability in MAFLD-associated CVD may hold translational potential for risk profiling and innovative therapeutic targeting.

Low Health Literacy, Lack of Knowledge, and Self-Control Hinder Healthy Lifestyles in Diverse Patients with Steatotic Liver Disease

INTRODUCTION

In parallel with the obesity and diabetes epidemics, steatotic liver disease (SLD) has emerged as a major global public health concern. The mainstay of therapy is counseling on weight loss and increased exercise. However, such lifestyle modifications infrequently lead to success. We aimed to identify barriers to diet and lifestyle modification in patients with SLD.

METHODS

Patients with SLD completed a 14-item questionnaire that assigned barriers to healthy eating to three categories: lack of knowledge, lack of self-control, and lack of time, with a higher summary score indicating more perceived barriers. We administered assessments of health literacy and physical activity. We analyzed the data using descriptive statistics and ordinal regression analysis.

RESULTS

We included 151 participants with a median age of 64; 54% were female and 68.2% were Hispanic. Median BMI was 31.9 kg/m2. Most respondents, 68.2%, had low health literacy and were either underactive, 29.1% or sedentary, 23.2%. Lack of self-control was the strongest barrier to achieving a healthy lifestyle, followed by lack of knowledge. Lack of time was not significant barrier. Patients with the most significant barriers were more likely to have obesity, low health literacy, and be sedentary.

DISCUSSION

Lack of self-control and knowledge are the greatest barriers to adopting a healthy lifestyle in patients with SLD. Future clinical interventions should integrate education that targets various health literacy levels with behavioral approaches to improve a sense of agency.

Modifying effects of 2,4-D and Glyphosate exposures on gut-liver-adipose tissue axis of diet-induced non-alcoholic fatty liver disease in mice

Nonalcoholic fatty liver disease (NAFLD), which is linked to western diet (WD) intake, affects 30% of the world's population and involves the crosstalk of liver steatosis, hypertrophy/inflammation of adipose tissue and deregulation of gut microbiome. Glyphosate and 2,4-D are some of the most applied herbicides worldwide, and their roles in NAFLD have not been investigated. Thus, the present study evaluated whether glyphosate and 2,4-D, in single or mixed exposure, alter WD-induced NAFLD in a mouse model. Male C57Bl/6 mice (n = 10/group) received a fat (30% lard, 0.02% cholesterol), and sucrose-rich diet (20%) and high sugar solution (23.1 and 18.9 g/L of fructose and glucose) for 6 months. Simultaneously, animals received glyphosate (0.05 or 5 mg/kg/day), 2,4-D (0.02 or 2 mg/kg/day), or their combination (0.05 +0.02 or 5 +2 mg/kg/day) by intragastrical administration (5 ×/week). Doses were based on the Acceptable Daily Intake (ADIs) or No Observed Adverse Effect Level (NOAEL) levels. Herbicide exposures featured differential responses. WD-induced obesity, hypercholesterolemia, and hyperglycemia remained unaltered. Compared to the group receiving only WD, only the concomitant exposure to WD and 2,4-D (2 mg) enhanced the percentage of mice with moderate/severe hepatic inflammation, CD68 macrophage infiltration, and malondialdehyde levels in the liver. In line, this herbicide modulated immune response- (including Cd4, C8b, Cd28, Cxcr3, Cxcr6) and oxidative stress-related (such as Gsta1, Gsta2, Gsta4, Gstm1, Gstm2, Gstm3, Gstm4, Nqo1, Gpx2) genes in the hepatic transcriptome analysis. This exposure also enriched pro-inflammatory Deferribacteres phylum in fecal microbiome. In general, the herbicide mixtures did not feature the same effects attributed to 2,4-D isolated exposure. Our findings indicate that 2,4-D, at a dose within the toxicological limits, was able to induce disturbances in mainly at the liver and gut axes involved in NAFLD development in male mice.

An international Delphi consensus statement on metabolic dysfunction-associated fatty liver disease and risk of chronic kidney disease

BACKGROUND

With the rising global prevalence of fatty liver disease related to metabolic dysfunction, the association of this common liver condition with chronic kidney disease (CKD) has become increasingly evident. In 2020, the more inclusive term metabolic dysfunction-associated fatty liver disease (MAFLD) was proposed to replace the term non-alcoholic fatty liver disease (NAFLD). The observed association between MAFLD and CKD and our understanding that CKD can be a consequence of underlying metabolic dysfunction support the notion that individuals with MAFLD are at higher risk of having and developing CKD compared with those without MAFLD. However, to date, there is no appropriate guidance on CKD in individuals with MAFLD. Furthermore, there has been little attention paid to the link between MAFLD and CKD in the Nephrology community.

METHODS AND RESULTS

Using a Delphi-based approach, a multidisciplinary panel of 50 international experts from 26 countries reached a consensus on some of the open research questions regarding the link between MAFLD and CKD.

CONCLUSIONS

This Delphi-based consensus statement provided guidance on the epidemiology, mechanisms, management and treatment of MAFLD and CKD, as well as the relationship between the severity of MAFLD and risk of CKD, which establish a framework for the early prevention and management of these two common and interconnected diseases.

Special Population: Lean Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with obesity but around 10% to 20% of patients with NAFLD have normal body mass index, a condition referred to as lean or nonobese NAFLD. Although lean patients more often have milder liver disease, a proportion may nonetheless develop steatohepatitis and advanced liver fibrosis. Both genetic and environmental factors contribute to the development of NAFLD. Noninvasive tests have similarly good accuracy as initial assessments for lean NAFLD. Future studies should determine the most appropriate treatment in this special population.

INASL-SAASL Consensus Statements on NAFLD Name Change to MAFLD

There is an ongoing debate on the change of terminology of non-alcoholic fatty liver disease (NAFLD) to metabolic associated fatty liver disease (MAFLD). Experts from the Indian National Association for Study of the Liver (INASL) and the South Asian Association for Study of the Liver (SAASL) involved in diagnosing, managing, and preventing NAFLD met in March 2022 to deliberate if the name change from NAFLD to MAFLD is appropriate, as proposed by a group of experts who published a "consensus" statement in 2020. Proponents of name change to MAFLD opined that NAFLD does not reflect current knowledge, and the term MAFLD was suggested as a more appropriate overarching term. However, this "consensus" group which proposed the name change to MAFLD did not represent the views and opinions of gastroenterologists and hepatologists, as well as perceptions of patients across the globe, given the fact that change of nomenclature for any disease entity is bound to have multidimensional impact on all aspects of patient care. This statement is the culmination of the participants' combined efforts who presented recommendations on specific issues concerning the proposed name change. The recommendations were then circulated to all the core group members and updated based on a systematic literature search. Finally, all the members voted on them using the nominal voting technique as per the standard guidelines. The quality of evidence was adapted from the Grades of Recommendation, Assessment, Development and Evaluation system.

Indian National Association for Study of the Liver (INASL) Guidance Paper on Nomenclature, Diagnosis and Treatment of Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease globally and in India. The already high burden of NAFLD in India is expected to further increase in the future in parallel with the ongoing epidemics of obesity and type 2 diabetes mellitus. Given the high prevalence of NAFLD in the community, it is crucial to identify those at risk of progressive liver disease to streamline referral and guide proper management. Existing guidelines on NAFLD by various international societies fail to capture the entire landscape of NAFLD in India and are often difficult to incorporate in clinical practice due to fundamental differences in sociocultural aspects and health infrastructure available in India. A lot of progress has been made in the field of NAFLD in the 7 years since the initial position paper by the Indian National Association for the Study of Liver on NAFLD in 2015. Further, the ongoing debate on the nomenclature of NAFLD is creating undue confusion among clinical practitioners. The ensuing comprehensive review provides consensus-based, guidance statements on the nomenclature, diagnosis, and treatment of NAFLD that are practically implementable in the Indian setting.

Metabolic dysfunction-associated fatty liver disease and excessive alcohol consumption are both independent risk factors for mortality

BACKGROUND AND AIMS

MAFLD often cooccurs with excessive alcohol consumption, while its prognostic value in this group remains unclear. We aimed to study the mortality risk of MAFLD in relation to excessive alcohol consumption and its potential interactions.

APPROACH AND RESULTS

We analyzed persons 25-74 years old enrolled in the National Health and Nutrition Examination Survey III cohort with available steatosis and alcohol data. Participants with viral hepatitis, body mass index < 18.5, and missing data on age or follow-up were excluded, leaving 12,656 participants for analysis with a median follow-up of 22.9 [20.9-24.8] years. MAFLD was defined as steatosis on ultrasound in the presence of metabolic dysfunction. Daily alcohol intake of ≥10 g in females and ≥20 g in males was considered excessive alcohol consumption. We quantified mortality risk with multivariate Cox regression for MAFLD and excessive alcohol consumption. Models were adjusted for age, age squared, sex, race, marital status, education, and smoking. MAFLD was present in 31% and excessive alcohol consumption in 13% and were both independently and simultaneously associated with increased mortality risk in fully adjusted models (adjusted HR [aHR], 1.21; 95% CI, 1.13-1.30 and aHR, 1.14; 95% CI, 1.04-1.26, respectively). Similarly, MAFLD was associated with increased mortality risk in participants with and without excessive alcohol consumption. Participants with both MAFLD and excessive alcohol consumption (4.0%) expressed the highest mortality risk (aHR, 1.47; 95% CI, 1.28-1.71). Results were consistent using the initial 10 years of follow-up, a stringent definition of excessive alcohol, and propensity score weighting.

CONCLUSIONS

MAFLD increases mortality risk independent of excessive alcohol consumption. This underscores the importance of MAFLD, even in patients with excessive alcohol consumption.

Diagnostic ability using fatty liver and metabolic markers for metabolic-associated fatty liver disease stratified by metabolic/glycemic abnormalities

AIMS/INTRODUCTION

Although several noninvasive predictive markers for fatty liver and metabolic markers have been used for fatty liver prediction, whether such markers can also predict metabolic-associated fatty liver disease (MAFLD) remains unclear. We aimed to examine the ability of existing fatty liver or metabolic markers to predict MAFLD.

MATERIALS AND METHODS

Participants in a high-volume center in Tokyo were classified into groups with and without MAFLD, based on the presence of metabolic abnormalities and fatty liver diagnosed through abdominal ultrasonography, between 2008 and 2018. The diagnostic abilities of three fatty liver markers: fatty liver index (FLI), hepatic steatosis index (HSI), and lipid accumulation product (LAP), and three common metabolic markers: waist-to-height ratio (WHR), body mass index (BMI), and waist circumference (WC), for predicting MAFLD, were evaluated. Analyses stratified by MAFLD subtypes were performed.

RESULTS

Of 92,374 individuals, 19,392 (36.1%) had MAFLD. The diagnostic performances for MAFLD prediction, measured as c-statistics, for FLI, HSI, LAP, WHR, BMI, and WC were 0.906, 0.892, 0.878, 0.844, 0.877, and 0.878, respectively. Optimal cutoff values for diagnosing MAFLD for FLI, HSI, LAP, WHR, BMI, and WC were 20.3, 32.7, 20.0, 0.49, 22.9, and 82.1, respectively. Analyses stratified by MAFLD subtypes, based on BMI and metabolic/glycemic abnormalities, suggested that FLI and HSI had acceptable (c-statistics >0.700) diagnostic abilities throughout all the analyses.

CONCLUSIONS

All six markers were excellent predictors of MAFLD in diagnosing among the general population, with FLI and HSI particularly useful among all sub-populations.

Lessons on Drug Development: A Literature Review of Challenges Faced in Nonalcoholic Fatty Liver Disease (NAFLD) Clinical Trials

NAFLD is the most common chronic liver disease worldwide, occurring in both obese and lean patients. It can lead to life-threatening liver diseases and nonhepatic complications, such as cirrhosis and cardiovascular diseases, that burden public health and the health care system. Current care is weight loss through diet and exercise, which is a challenging goal to achieve. However, there are no FDA-approved pharmacotherapies for NAFLD. This review thoroughly examines the clinical trial findings from 22 drugs (Phase 2 and above) and evaluates the future direction that trials should take for further drug development. These trialed drugs can broadly be categorized into five groups-hypoglycemic, lipid-lowering, bile-pathway, anti-inflammatory, and others, which include nutraceuticals. The multitude of challenges faced in these yet-to-be-approved NAFLD drug trials provided insight into a few areas of improvement worth considering. These include drug repurposing, combinations, noninvasive outcomes, standardization, adverse event alleviation, and the need for precision medicine with more extensive consideration of NAFLD heterogenicity in drug trials. Understandably, every evolution of the drug development landscape lies with its own set of challenges. However, this paper believes in the importance of always learning from lessons of the past, with each potential improvement pushing clinical trials an additional step forward toward discovering appropriate drugs for effective NAFLD management.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

Nonalcoholic Fatty Liver Disease Without Metabolic-associated Fatty Liver Disease and the Risk of Metabolic Syndrome

BACKGROUND & AIMS

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) was proposed to replace nonalcoholic fatty liver disease (NAFLD). Some people fulfill diagnostic criteria of NAFLD but not MAFLD (NAFLD without MAFLD), but the clinical implications of NAFLD in these subjects is unknown.

METHODS

We followed cohort of 12,197 men and women 20 years of age or older without metabolic dysfunction (defined by MAFLD criteria), heavy alcohol use, chronic viral hepatitis, liver cirrhosis, or malignancy for their risk of incident metabolic syndrome defined by Adult Treatment Panel III criteria.

RESULTS

By design, none of the study participants had MAFLD at baseline. The prevalence of NAFLD among participants without metabolic dysfunction meeting MAFLD criteria and without significant alcohol intake was 7.6%. During 74,508 person-years of follow-up, 2179 participants developed metabolic syndrome. The fully adjusted hazard ratio for metabolic syndrome comparing participants with NAFLD to those without it was 1.61 (95% confidence interval, 1.42-1.83). The increased risk of incident metabolic syndrome associated with NAFLD persisted for all studied subgroups, and the association was stronger for those with increased waist circumference (P for interaction = .029) and those without elevated triglycerides levels (P for interaction = .047).

CONCLUSION

In this large cohort, participants with NAFLD without MAFLD were at higher risk of developing metabolic syndrome compared to participants with no NAFLD and no MAFLD. Using MAFLD criteria may miss opportunities for early intervention in these subjects.

Insight into Potential Interactions of Thyroid Hormones, Sex Hormones and Their Stimulating Hormones in the Development of Non-Alcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common manifestation of metabolic syndrome. In addition to lifestyle, endocrine hormones play a role in the dysregulation of hepatic metabolism. The most common endocrine hormones contributing to metabolic syndrome are alterations in the levels of thyroid hormones (THs, predominantly in subclinical hypothyroidism) and of sex hormones (in menopause). These hormonal changes influence hepatic lipid and glucose metabolism and may increase hepatic fat accumulation. This review compares the effects of sex hormones, THs and the respective stimulating hormones, Thyroid-Stimulating Hormone (TSH) and Follicle-Stimulating Hormone (FSH), on the development of hepatosteatosis. TSH and FSH may be more relevant to the dysregulation of hepatic metabolism than the peripheral hormones because metabolic changes were identified when only levels of the stimulating hormones were abnormal and the peripheral hormones were still in the reference range. Increased TSH and FSH levels appear to have additive effects on the development of NAFLD and to act independently from each other.

The Role of Gut–Liver Axis in Gut Microbiome Dysbiosis Associated NAFLD and NAFLD-HCC

Nonalcoholic fatty liver disease (NAFLD) is considered as one of the most prevalent chronic liver diseases worldwide due to the rapidly rising prevalence of obesity and metabolic syndrome. As a hepatic manifestation of metabolic disease, NAFLD begins with hepatic fat accumulation and progresses to hepatic inflammation, termed as non-alcoholic steatohepatitis (NASH), hepatic fibrosis/cirrhosis, and finally leading to NAFLD-related hepatocellular carcinoma (NAFLD-HCC). Accumulating evidence showed that the gut microbiome plays a vital role in the initiation and progression of NAFLD through the gut–liver axis. The gut–liver axis is the mutual communication between gut and liver comprising the portal circulation, bile duct, and systematic circulation. The gut microbiome dysbiosis contributes to NAFLD development by dysregulating the gut–liver axis, leading to increased intestinal permeability and unrestrained transfer of microbial metabolites into the liver. In this review, we systematically summarized the up-to-date information of gut microbiome dysbiosis and metabolomic changes along the stages of steatosis, NASH, fibrosis, and NAFLD-HCC. The components and functions of the gut–liver axis and its association with NAFLD were then discussed. In addition, we highlighted current knowledge of gut microbiome-based treatment strategies targeting the gut–liver axis for preventing NAFLD and its associated HCC.

Liver biopsy for assessment of chronic liver diseases: a synopsis

The world-wide increase in chronic liver disease (CLD) calls for refinement of diagnostic and prognostic measures for early and accurate disease detection and management. Regardless of the aetiology, liver biopsy allows direct visualisation of specimen under the microscope. It facilitates histological evaluation of disease-specific morphological alterations. Thereby, it aids in disease diagnosis, prognosis, and assessment of treatment compliance/response. Indeed, with the advent of non-invasive methods, liver biopsy is used less frequently than before, but it is still considered as a gold standard for staging and grading several CLDs. This short review revisits liver biopsy. It highlights the significance of liver biopsy in evaluating CLDs and explains the commonly used Ishak, METAVIR and Batts-Ludwig scoring systems for grading and staging CLDs. The utility of liver biopsy in examining alcohol-related liver disease and non-alcoholic fatty liver disease (NAFLD) is discussed along with the disease-specific alcoholic hepatitis histology score (AHHS) and non-alcoholic fatty liver disease activity score (NAS). Additionally, the review elaborates on the role of liver biopsy in evaluating viral hepatitis, haemochromatosis, and hepatocellular carcinoma. Contextual explanation on the diagnosis of metabolic dysfunction-associated liver disease (MAFLD) is provided. The significance and clinical indications of repeat biopsy are also explained. Lastly, caveats and limitations associated with liver biopsy are reviewed. Essentially, this review collates the application of liver biopsy in assessing various CLDs and provides succinct explanations of the core scoring systems, all under one roof. It is clinically relevant and provides a useful synopsis to budding scientists and hepato-pathologists.