Risk for development of severe liver disease in lean patients with nonalcoholic fatty liver disease: A long-term follow-up study

Clinical characteristics of lean and non-lean non-alcoholic fatty liver disease: a cross-sectional study

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) affects more than a quarter of the global population and has become the world's number one chronic liver disease, seriously jeopardizing public life and health. Despite the new terminology of metabolic dysfunction-associated steatotic liver disease (MASLD) has been proposed, the mechanisms underlying the heterogeneity across BMI stratification in non-alcoholic fatty liver disease (NAFLD) remain unclear. The aim of this study was to reveal the differences in metabolic and fibrotic characteristics between lean (BMI < 23 kg/m2) and non-lean NAFLD in an Asian population.

METHODS

The current study collected NAFLD patients from the physical examination population. Patients were divided into two groups by BMI to compare their clinical parameters, including lean (BMI < 23 kg/m2) and non-lean (BMI ≥ 23 kg/m2) and fibrosis subgroups (with a threshold of LSM = 8 kPa) and analyzed for risk factors by logistic regression models.

RESULTS

Of the 11,577 NAFLD patients who participated in the study, there were 916 lean and 10,661 non-lean. The non-lean group was younger than the lean group (median age 50 vs. 52 years, P < 0.001) and had a significantly higher prevalence of hypertension (28.0% vs. 18.3%), diabetes mellitus (10.1% vs. 6.1%), and liver fibrosis (9.1% vs. 5.1%) (all P < 0.001). Analysis of metabolic indexes showed that TyG, TyG-BMI, TG/HDL-C and APRI were higher in the non-lean group (all P < 0.001). Gender stratification revealed that ALT was significantly higher in the male non-lean group, while HDL-C was lower in the female non-lean group (1.35 vs. 1.47 mmol/L). Multiple regression suggested that the risk of fibrosis was independently associated with CAP values and fasting glucose, BMI, direct bilirubin, globulin, and age in the non-lean group, whereas the risk was mainly driven by GGT and ALP in the lean group.

CONCLUSIONS

Non-lean NAFLD patients showed more significant metabolic disturbances and risk of liver fibrosis. Although metabolic indicators (TyG, FIB-4) have limited predictive value for liver fibrosis, they are strongly associated with metabolic risk in MASLD.

Association of metabolic dysfunction-associated fatty liver disease with white matter hyperintensity and cognitive decline: A longitudinal cohort study

AIMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) has recently been proposed to describe the hepatic steatosis associated with metabolic abnormalities. Substantial evidence has shown that hepatic steatosis may be linked with cognitive impairment and dementia. This study aimed to clarify the association between MAFLD and brain structural and cognitive changes.

MATERIALS AND METHODS

We analysed data from 2155 participants with both baseline and 4-year follow-up brain magnetic resonance images and neuropsychological measures from the Ansan cohort of the Korean Genome Epidemiology Study. The presence of hepatic steatosis was defined as a liver attenuation index (LAI) value <5 Hounsfield units using computed tomography.

RESULTS

Over a median follow-up of 4.1 years, MAFLD was associated with an increased risk of white matter hyperintensity (WMH) (RR 1.35; 95% CI 1.09-1.66, p = 0.006), but not with brain volume changes. When examined by individual components of MAFLD, the presence of hepatic steatosis was an independent factor associated with the risk of WMH regardless of metabolic derangements. Lower LAI values were linearly associated with greater executive function Z score decline (p = 0.007). This relationship was more evident in the non-obese group (body mass index <25 kg/m2, p for interaction = 0.003).

CONCLUSIONS

MAFLD was associated with an increased risk of WMH over 4.1 years in middle-aged adults. The hepatic steatosis itself was independently associated with an increased risk of WMH regardless of comorbid metabolic abnormalities. The degree of hepatic steatosis was associated with decreased executive function, especially in non-obese individuals.

Post-hoc analysis of the tofogliflozin post-marketing surveillance study (J-STEP/LT): Tofogliflozin improves liver function in type 2 diabetes patients regardless of BMI

AIMS/INTRODUCTION

Patients with type 2 diabetes are at high risk of developing steatotic liver disease (SLD). Weight loss has proven effective in treating metabolic dysfunction-associated steatotic liver disease (MASLD) in obese patients with type 2 diabetes, with sodium-glucose cotransporter 2 (SGLT2) inhibitors showing promising results. However, lean MASLD is more prevalent in Japan, necessitating alternative approaches to body weight reduction.

MATERIALS AND METHODS

We used the J-STEP/LT dataset including up to 3-year treatment data to analyze the effects of the SGLT2 inhibitor tofogliflozin on liver function and treatment safety and conducted a subgroup analysis based on body mass index (BMI; kg/m2, <20, 20-<23, 23-<25, 25-<30, and ≥30).

RESULTS

This study included 4,208 participants. Tofogliflozin significantly reduced alanine aminotransferase (ALT) levels in participants with baseline ALT levels >30 U/L across all BMI groups, with median changes of -12, -16, -13, -15, and -15 U/L, respectively (P = 0.9291 for trends). However, median changes in body weight with tofogliflozin were -2.00, -2.75, -2.00, -3.00, and -3.80 kg, respectively (P < 0.0001 for trends), with no significant weight loss observed in the BMI <20 group. ALT levels were also significantly decreased in participants who did not lose weight. Safety assessments according to BMI and age categories revealed no clear differences in the frequency of adverse events.

CONCLUSIONS

Tofogliflozin reduced ALT levels without substantial body weight reduction among lean participants. These findings suggest that SGLT2 inhibitors may be a viable treatment option for non-obese patients with type 2 diabetes and SLD.

Opportunistic assessment of steatotic liver disease in lung cancer screening eligible individuals

BACKGROUND

Steatotic liver disease (SLD) is a potentially reversible condition but often goes unnoticed with the risk for end-stage liver disease.

PURPOSE

To opportunistically estimate SLD on lung screening chest computed tomography (CT) and investigate its prognostic value in heavy smokers participating in the National Lung Screening Trial (NLST).

MATERIAL AND METHODS

We used a deep learning model to segment the liver on non-contrast-enhanced chest CT scans of 19,774 NLST participants (age 61.4 ± 5.0 years; 41.2% female) at baseline and on the 1-year follow-up scan if no cancer was detected. SLD was defined as hepatic fat fraction (HFF) ≥5% derived from Hounsfield unit measures of the segmented liver. Participants with SLD were categorized as lean (body mass index [BMI] < 25 kg/m2) and overweight (BMI ≥ 25 kg/m2). The primary outcome was all-cause mortality. Cox proportional hazard regression assessed the association between (1) SLD and mortality at baseline and (2) the association between a change in HFF and mortality within 1 year.

RESULTS

There were 5.1% (1000/19,760) all-cause deaths over a median follow-up of 6 (range, 0.8-6) years. At baseline, SLD was associated with increased mortality in lean but not in overweight/obese participants as compared to participants without SLD (hazard ratio [HR] adjusted for risk factors: 1.93 [95% confidence interval 1.52-2.45]; p = 0.001). Individuals with an increase in HFF within 1 year had a significantly worse outcome than participants with stable HFF (HR adjusted for risk factors: 1.29 [1.01-1.65]; p = 0.04).

CONCLUSION

SLD is an independent predictor for long-term mortality in heavy smokers beyond known clinical risk factors.

Associations of MAFLD subtypes and air pollutants with multi-system morbidity and all-cause mortality: A prospective cohort study

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) and air pollution are both significant health concerns. However, their combined effects on multi-system morbidity and all-cause mortality remain poorly understood.

METHODS

We analyzed data from 434,417 UK Biobank participants, categorizing them into four groups: non-MAFLD, MAFLD-diabetes, MAFLD-lean, and MAFLD-overweight/obesity. To evaluate the long-term effects of air pollution exposure, we used time-varying Cox proportional hazard models to assess four air pollutants: particulate matter with an aerodynamic diameter < 2.5 μm (PM2.5), PM10, nitrogen dioxide (NO2), and nitrogen oxides (NOx). We examined the associations between these air pollutants, MAFLD subtypes, and their joint impact on multi-system morbidity and all-cause mortality. Furthermore, we explored the additive and multiplicative interactions between air pollutants and MAFLD subtypes.

RESULTS

At baseline, 15,325 participants were classified as MAFLD-diabetes, 3341 as MAFLD-lean, and 140,934 as MAFLD-overweight/obesity. Among these groups, MAFLD-diabetes was most strongly associated with adverse outcomes compared to other subtypes. Air pollution exposure had a synergistic effect on cirrhosis risk across all MAFLD subtypes, with the most pronounced effects observed for PM2.5 [relative excess risk due to interaction (RERI): 2.10 (0.94, 3.26)] and NO2 [RERI:1.85 (0.67, 3.04)] in MAFLD-lean group. Positive additive and multiplicative interactions between air pollutants and MAFLD subtypes were also observed for coronary artery disease (CAD), with the exception of nitrogen oxide in the MAFLD-lean group. Additionally, only the MAFLD-diabetes demonstrated significant positive additive interactions with all four air pollutants in relation to chronic kidney disease (CKD).

CONCLUSIONS

This study highlights the distinct impacts of MAFLD subtypes on multi-system morbidity and all-cause mortality, underscoring the critical need for targeted prevention and treatment strategies, particularly for individuals with MAFLD-diabetes. Our findings reveal significant additive and synergistic effects of air pollution exposure on the risks of cirrhosis, CAD, and CKD among MAFLD patients.

Metabolic dysfunction-associated steatotic liver disease: heterogeneous pathomechanisms and effectiveness of metabolism-based treatment

The global epidemic of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. People with MASLD can progress to cirrhosis and hepatocellular carcinoma and are at increased risk of developing type 2 diabetes, cardiovascular disease, chronic kidney disease, and extrahepatic cancers. Most people with MASLD die from cardiac-related causes. This outcome is attributed to the shared pathogenesis of MASLD and cardiometabolic diseases, involving unhealthy dietary habits, dysfunctional adipose tissue, insulin resistance, and subclinical inflammation. In addition, the steatotic and inflamed liver affects the vasculature and heart via increased glucose production and release of procoagulant factors, dyslipidaemia, and dysregulated release of hepatokines and microRNAs. However, there is substantial heterogeneity in the contributors to the pathophysiology of MASLD, which might influence its rate of progression, its relationship with cardiometabolic diseases, and the response to therapy. The most effective non-pharmacological treatment approaches for people with MASLD include weight loss. Paradoxically, some effective pharmacological approaches to improve liver health in people with MASLD are associated with no change in bodyweight or even with weight gain, and similar response heterogeneity has been observed for changes in cardiometabolic risk factors. In this Review, we address the heterogeneity of MASLD with respect to its pathogenesis, outcomes, and metabolism-based treatment responses. Although there is currently insufficient evidence for the implementation of precision medicine for risk prediction, prevention, and treatment of MASLD, we discuss whether knowledge about this heterogeneity might help achieving this goal in the future.

Central Obesity is an Independent Determinant of Advanced Fibrosis in Lean Patients With Nonalcoholic Fatty Liver Disease

Background

The current definition of lean is based on body mass index (BMI). However, BMI is an imperfect surrogate for adiposity and provides no information on central obesity (CO). Hence, we explored the differences in clinical profile and liver disease severity in lean patients with nonalcoholic fatty liver disease (NAFLD) with and without CO.

Methods

One hundred seventy lean patients with NAFLD (BMI <23 kg/m2) were divided into two groups depending upon the presence or absence of CO (waist circumference ≥80 cm in females and ≥90 cm in males). Noninvasive assessment of steatosis was done by ultrasound and controlled attenuation parameter (CAP), while fibrosis was assessed with FIB-4 and liver stiffness measurement (LSM). FibroScan-AST (FAST) score was used for non-invasive prediction of NASH with significant fibrosis.

Results

Of 170 patients with lean NAFLD, 96 (56.5%) had CO. Female gender (40.6% vs. 17.6%, P = 0.001), hypertriglyceridemia (58.3% vs. 39.2%, P = 0.01) and metabolic syndrome (23.9% vs. 4.1%, P < 0.001) were more common in the CO group. There was a poor correlation between BMI and waist circumference (r = 0.24, 95% CI: 0.09-0.38). Grade 2-3 steatosis on ultrasound was significantly more common in CO patients (30% vs. 12.3%, P = 0.007). CAP [312.5 (289.8-341) dB/m vs. 275 (248-305.1) dB/m, P = 0.002], FAST score [0.42 (0.15-0.66) vs. 0.26 (0.11-0.39), P = 0.04], FIB-4 and LSM were higher in those with CO. Advanced fibrosis was more prevalent among CO patients using FIB-4 (19.8% vs 8.1%, P = 0.03) and LSM (9.5% vs. 0, P = 0.04). CO was independently associated with advanced fibrosis after adjusting for BMI and metabolic risk factors (aOR: 3.11 (1.10-8.96), P = 0.03). Among these 170 patients, 142 fulfilled metabolic dysfunction associated steatotic liver disease (MASLD) criteria. CO was also an independent risk factor for advanced fibrosis in MASLD (3.32 (1.23-8.5), P = 0.02).

Conclusion

Lean patients with NAFLD or MASLD and CO have more severe liver disease compared to those without CO.

Long-term outcomes and risk modifiers of metabolic dysfunction-associated steatotic liver disease between lean and non-lean populations

One-third of adults across the globe exhibit metabolic dysfunction-associated steatotic liver disease (MASLD)-formerly known as nonalcoholic fatty liver disease (NAFLD). To date, MASLD is the fastest-growing etiology of chronic liver disease and hepatocellular carcinoma (HCC). Besides the population with obesity, MASLD can also be found in lean populations, accounting for 13% of the global population, especially Asians. Notably, individuals with lean MASLD face equal or higher overall mortality rates compared to their non-lean counterparts. Risk modifiers encompass advanced age, hepatic fibrosis, and type 2 diabetes mellitus (T2DM). Moreover, the population with lean MASLD is associated with an increased risk of HCC, while their non-lean counterparts are more prone to cardiovascular outcomes and T2DM. Existing evidence indicates a similar risk of liver-related events and extrahepatic cancer between the two groups. However, MASLD-related genetic variants, such as PNPLA3 and TM6SF2, did not significantly affect mortality between the two populations. Still, underreporting alcohol consumption and regional representation limits the study's comprehensiveness. Longitudinal studies and mechanistic explorations are needed to understand differences in lean versus non-lean MASLD populations. This review highlights the need for awareness and tailored interventions in managing MASLD, considering lean individuals' unique risks.

Liver diseases and hepatocellular carcinoma in the Asia-Pacific region: burden, trends, challenges and future directions

Globally, nearly half of deaths from cirrhosis and chronic liver diseases (CLD) and three-quarters of deaths from hepatocellular carcinoma (HCC) occur in the Asia-Pacific region. Chronic hepatitis B is responsible for the vast majority of liver-related deaths in the region. Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common form of CLD, affecting an estimated 30% of the adult population. Compared with people of European descent, people from the Asia-Pacific region carry more genetic variants associated with MASLD and its progression. Alcohol is a fast-growing cause of CLD and HCC in Asia as a result of the rising per-capita consumption of alcohol. Drug-induced liver injury is under-recognized and probably has a high prevalence in this region. The epidemiological and outcome data of acute-on-chronic liver failure are heterogeneous, and non-unified definitions across regions contribute to this heterogeneity. CLDs are severely underdiagnosed, and effective treatments and vaccinations are underutilized. In this Review, we highlight trends in the burden of CLD and HCC in the Asia-Pacific region and discuss the rapidly changing aetiologies of liver disease. We examine the multiple gaps in the care cascade and propose mitigating strategies and future directions.

Decoding the fatty liver-hyperuricemia link in the obese and nonobese hypertensive patients: insights from a cohort study

Metabolic-dysfunction-associated fatty liver disease (MAFLD) and serum uric acid are closely related to cardiovascular and cerebrovascular diseases. However, the causal association between MAFLD and serum uric acid remains unclear. A total of 3417 patients without hyperuricemia were included in the final analysis. MAFLD was defined as fatty liver index (FLI) ≥ 30. Multivariate Cox regression analysis was used to explore the association between FLI and new-onset hyperuricemia. Restricted cubic splines and threshold saturation effect analysis were used to detect nonlinear associations. The mean age was 62.8 ± 8.3 year, and 68.5% were women. A total of 738 (21.6%) hypertensive patients developed new-onset hyperuricemia, 388 (11.4%) new-onset hyperuricemia10 and 190 (5.6%) new-onset hyperuricemia20 during the 4-year midday follow-up period. In the fully adjusted model, compared with the Q1 (FLI ≤ 8.5) group, the risk of hyperuricemia increased by 56% (HR: 1.56; 95% CI: 1.02, 2.38) in the Q4 (FLI > 39.4) group, new-onset hyperuricemia10 increased by 108% (HR: 2.08; 95% CI: 1.15, 3.78), and new-onset hyperuricemia20 increased by 156% (HR: 2.56; 95% CI: 1.11, 5.94), respectively. Saturation effects showed a nonlinear association between FLI and new-onset hyperuricemia (p for log likelihood ratio test < 0.05). Subgroup analysis and stratified analysis showed that there had a significantly higher risk of new-onset hyperuricemia in the patients with normal body mass index (< 24 kg/m2) (p for interaction: 0.018) and non-central obesity (p for interaction: 0.024). MAFLD is an independent risk factor for hyperuricemia in hypertensive patients, especially in patients with normal body mass index and non-central obesity.

Characteristics of intestinal flora in nonobese nonalcoholic fatty liver disease patients and the impact of ursodeoxycholic acid treatment on these features

The study aimed to investigate the alterations in gut microbiota among nonobese individuals with nonalcoholic fatty liver disease (NAFLD) and their response to treatment with ursodeoxycholic acid (UDCA). A total of 90 patients diagnosed with NAFLD and 36 healthy subjects were recruited to participate in this study. Among them, a subgroup of 14 nonobese nonalcoholic steatohepatitis (NASH) were treated with UDCA. Demographic and serologic data were collected for all participants, while stool samples were obtained for fecal microbiome analysis using 16S sequencing. In nonobese NAFLD patients, the alpha diversity of intestinal flora decreased (Shannon index, p < 0.05), and the composition of intestinal flora changed (beta diversity, p < 0.05). The abundance of 20 genera, including Fusobacterium, Lachnoclostridium, Klebsiella, etc., exhibited significant changes (p < 0.05). Among them, nine species including Fusobacterium, Lachnoclostridium, Klebsiella, etc. were found to be associated with abnormal liver enzymes and glucolipid metabolic disorders. Among the 14 NASH patients treated with UDCA, improvements were observed in terms of liver enzymes, CAP values, and E values (p < 0.05), however, no improve the glucolipid metabolism. While the alpha diversity of intestinal flora did not show significant changes after UDCA treatment, there was a notable alteration in the composition of intestinal flora (beta diversity, p < 0.05). Furthermore, UCDA treatment led to an improvement in the relative abundance of Alistipes, Holdemanella, Gilisia, etc. among nonobese NASH patients (p < 0.05). Nonobese NAFLD patients exhibit dysbiosis of the intestinal microbiota. UDCA can ameliorate hepatic enzyme abnormalities and reduce liver fat content in nonobese NASH patients, potentially through its ability to restore intestinal microbiota balance.

Mechanistic role of long non-coding RNAs in the pathogenesis of metabolic dysfunction-associated steatotic liver disease and fibrosis

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously referred to as non-alcoholic fatty liver disease, encompasses a broad range of hepatic metabolic disorders primarily characterised by the disruption of hepatic lipid metabolism, hepatic lipid accumulation and steatosis. Severe cases of MASLD might progress to metabolic dysfunction-associated steatohepatitis, characterised by hepatic inflammation, hepatocyte ballooning degeneration, activation of hepatic stellate cells (HSCs) and fibrogenesis. It may further progress to hepatocellular carcinoma. In the liver, long non-coding RNAs (lncRNAs) target multiple metabolic pathways in hepatocytes, HSCs, and Kupffer cells at different stages of MASLD and liver fibrosis. In this study, we overview recent findings on the potential role of lncRNAs in the pathogenesis of MASLD and liver fibrosis via modulation of de novo lipid synthesis, fatty acid β-oxidation, lipotoxicity, oxidative stress, metabolic inflammation, mammalian target of rapamycin signalling, apoptosis, ubiquitination and fibrogenesis. We critically assess the literature reports that investigate the complex interplay between lncRNA, microRNA and key mediators in liver injury, in both human participants and animal models of MASLD and liver fibrosis. We also highlight the therapeutic potential of lncRNAs in chronic liver diseases.

Liver and cardiovascular outcomes in lean non-alcoholic fatty liver disease: an updated systematic review and meta-analysis of about 1 million individuals

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) is present in lean people. However, the magnitude of the prognostic hepatic and cardiovascular risk in these patients compared to non-lean counterparts remains unclear. We aimed to investigate this topic, and to explore whether these risks change based on factors related to NAFLD severity.

METHODS

PubMed and Embase databases were searched for cohort studies (published through April 2024) that evaluated liver and cardiovascular (CV) outcomes in lean and non-lean individuals with NAFLD and reported unadjusted or adjusted data. We pooled risk ratios (RRs) or hazard ratios (HRs) using a random-effects modeling and performed subgroup and meta-regressions analyses.

RESULTS

We identified 22 studies with over 1 million NAFLD patients (13.0% were lean). Lean NAFLD showed a similar risk of liver-related events in unadjusted analysis (RR 1.08, 95% CI 0.79-1.49, I2 = 31%), but a higher risk in adjusted analysis (HR 1.66, 95% CI 1.17-2.36, I2 = 83%) compared to non-lean NAFLD. Lean NAFLD had a higher risk of liver-related mortality (RR 2.22, 95% CI 1.57-3.15, I2 = 0%; HR 2.26, 95% CI 1.14-4.51, I2 = 0%). For CV outcomes, lean NAFLD had a lower risk of any cardiovascular disease in unadjusted analysis (RR = 0.82, 95% CI 0.70-0.95, I2 = 88%), but similar risk in adjusted analysis (HR 0.89, 95% CI 0.77-1.02, I2 = 78%), and similar risk of cardiovascular mortality (RR 1.09, 95% CI 0.71-1.66, I2 = 85%; HR 1.26, 95% CI 0.89-1.78, I2 = 46%) compared to non-lean NAFLD.

CONCLUSIONS

Lean NAFLD patients have worse liver outcomes, but similar CV outcomes compared to non-lean NAFLD patients, highlighting the importance of monitoring both groups closely.

Clinical characteristics of lean metabolic-associated fatty liver disease and the impact of concurrent diabetes mellitus

Objectives

Metabolic-associated fatty liver disease (MAFLD) was proposed in 2020 to replace the original term nonalcoholic fatty liver disease (NAFLD) with new diagnostic criteria. The disease risks of lean and overweight/obese MAFLD patients remain controversial.

Materials and Methods

The participants from the Taiwan biobank cohort were included. Advanced liver fibrosis is defined as NAFLD fibrosis score (NFS) >0.675. We use carotid plaques of duplex ultrasounds to diagnose atherosclerosis.

Results

A total of 20,058 participants (age 55.67 ± 10.32; males 37.6%) were included in the final analysis. Seven thousand eight hundred and forty-three (39.1%) participants were diagnosed with MAFLD. Of them, 965 (12.3%) were lean MAFLD patients. Among lean MAFLD patients, 25.6% were comorbid with diabetes mellitus (DM). Lean MAFLD patients were older and had higher percentages of females and DM than overweight/obese MAFLD patients. After propensity score matching for age and sex, they had lower levels of NFS but a higher percentage of carotid plaques. Among four subtypes of MAFLD including "lean with DM," "lean without DM," "overweight/obese with DM," and "overweight/obese without DM," logistic regression showed that "lean with DM" subjects had the highest risk of atherosclerosis and "overweight/obese with DM" subjects had the highest risk of advanced liver fibrosis in MAFLD patients.

Conclusion

The population-based study revealed that lean MAFLD patients make up 12.3% of all MAFLD patients, and they have a higher proportion of coexisting diabetes. Among lean MAFLD patients concurrent with diabetes, they have the highest risk of atherosclerosis and should receive special attention clinically.

Incidence rates of hepatocellular carcinoma based on risk stratification in steatotic liver disease for precision medicine: A real-world longitudinal nationwide study

BACKGROUND

Detailed subgroup incidence rates for steatotic liver disease (SLD)-related hepatocellular carcinoma (HCC) are critical to inform practice and public health interventions but remain sparse. We aimed to fill in this gap.

METHODS AND FINDINGS

In a retrospective cohort study of adults with SLD from the United States (US) Merative Marketscan Research Databases (1/2007 to 12/2021), we estimated HCC incidence stratified by sex, age, cirrhosis, diabetes mellitus (DM), and a combination of all these 4 factors. We excluded patients with significant alcohol use and chronic viral hepatitis. We analyzed data from 741,816 patients with SLD (mean age 51.5 ± 12.8 years, 46% male, 14.7% cirrhosis). During a 2,410,166 person-years (PY) follow-up, 1,740 patients developed HCC. The overall HCC incidence yielded 0.72 per 1,000 PY (95% confidence interval [CI, 0.68, 0.75]). The incidence was higher in males (0.95, 95% CI [0.89, 1.01]) compared to females (0.52, 95% CI [0.48, 0.56]) (p < 0.001). For those with cirrhosis, the incidence was significantly higher at 4.29 (95% CI [4.06, 4.51]) compared to those without cirrhosis (0.14, 95% CI [0.13, 0.16]) (p < 0.001). Additionally, the incidence was higher in patients with DM (1.19, 95% CI [1.12, 1.26]) compared to those without DM (0.41, 95% CI [0.38, 0.44]) (p < 0.001). Chronic kidney disease (CKD) was also associated with a higher HCC incidence of 2.20 (95% CI [2.00, 2.41]) compared to those without CKD (0.58, 95% CI [0.55, 0.62]) (p < 0.001). Similarly, individuals with cardiovascular disease (CVD) had a higher HCC incidence of 1.89 (95% CI [1.75, 2.03]) compared to those without CVD (0.51, 95% CI [0.48, 0.54]) (p < 0.001). Finally, the incidence of HCC was significantly higher in patients with non-liver cancer (3.90, 95% CI [3.67, 4.12]) compared to those without other cancers (0.29, 95% CI [0.26, 0.31]) (p < 0.001). On further stratification, HCC incidence incrementally rose by 10-year age intervals, male sex, cirrhosis, and DM, reaching 19.06 (95% CI [16.10, 22.01]) and 8.44 (95% CI [6.78, 10.10]) in males and females, respectively, but only 0.04 for non-diabetic, noncirrhotic aged <40 years patients in both sexes. The main limitation of this methodology is the potential misclassification of the International Classification of Diseases (ICD) codes inherent in claims database studies.

CONCLUSIONS

This nationwide study provided robust granular estimates for SLD-related HCC incidence stratified by several key risk factors. In addition to cirrhosis, future surveillance strategies, prevention, public health initiatives, and future research models should also take into account the impact of sex, age, and DM.

Natural history and progression of metabolic dysfunction-associated steatotic liver disease

The natural history of metabolic dysfunction-associated steatotic liver disease (MASLD), previously referred to as non-alcoholic fatty liver disease (NAFLD), is complex and long. A minority of patients develop inflammation and risk progressive fibrosis that can result in cirrhosis. Progression to cirrhosis occurs in 3-5% of patients and often takes more than 20 years. This narrative review presents an update on the natural history of MASLD, discussing studies and risk estimates for progression to severe outcomes, such as decompensated cirrhosis or hepatocellular carcinoma. We highlight the dynamic progression of liver damage, how to identify patients whose disease progresses over time, and how risk factors might be mitigated to reduce the risk for disease progression.

Analysis of Serum Bile Acid Profile Characteristics and Identification of New Biomarkers in Lean Metabolic Dysfunction-Associated Fatty Liver Disease Based on LC-MS/MS

Objectives

Plasma bile acid (BA) has been widely studied as pathophysiological factors in chronic liver disease. But the changes of plasma BA level in lean metabolic dysfunction-associated fatty liver disease (MAFLD) remains unclear. Here, we clarified the BA metabolic characteristics of lean MAFLD and explored its significance and mechanism as a marker.

Methods

We employed ultra-performance liquid chromatography tandem mass spectrometry based on BA metabonomics to characterize circulating bile acid in lean MAFLD patients. Explore its significance as serum biomarkers by further cluster analysis, functional enrichment analysis, and serum concentration change analysis of differential BAs. Evaluation of diagnostic value of differential BAs by ROC analysis.

Results

A total of 65 BAs were detected and 17 BAs were identified which showed different expression in the lean-MAFLD group compared with the normal group. Functional annotation and enrichment analysis of KEGG and HMDB showed that differential BAs were mainly related to bile acid biosynthesis, bile secretion, cholesterol metabolism, and familial hypercholangitis, involving diseases including but not limited to cirrhosis, hepatocellular carcinoma, chronic active hepatitis, colorectal cancer, acute liver failure, and portal vein obstruction. ROC analysis displayed that the 6 BA metabolites (GCDCA-3S, GUDCA-3S, CDCA-3S, NCA, TCDCA, and HDCA) exhibited well differential diagnostic ability in discriminating between lean MAFLD patients and normal individuals with an area under the curve (AUC) ⩾0.85.

Conclusions

We delineated the characteristics of BA level in patients with lean MAFLD, and identified 6 potential plasma BA biomarkers of lean MAFLD.

The Association between Educational Attainment and the Risk of Nonalcoholic Fatty Liver Disease among Chinese Adults: Findings from the REACTION Study

Background/Aims

: Low educational attainment is a well-established risk factor for nonalcoholic fatty liver disease (NAFLD) in developed areas. However, the association between educational attainment and the risk of NAFLD is less clear in China.

Methods

: A cross-sectional study including over 200,000 Chinese adults across mainland China was conducted. Information on education level and lifestyle factors were obtained through standard questionnaires, while NAFLD and advanced fibrosis were diagnosed using validated formulas. Outcomes included the risk of NAFLD in the general population and high probability of fibrosis among patients with NAFLD. Logistic regression analysis was employed to estimate the risk of NAFLD and fibrosis across education levels. A causal mediation model was used to explore the potential mediators.

Results

: Comparing with those receiving primary school education, the multi-adjusted odds ratios (95% confidence intervals) for NAFLD were 1.28 (1.16 to 1.41) for men and 0.94 (0.89 to 0.99) for women with college education after accounting for body mass index. When considering waist circumference, the odds ratios (95% CIs) were 0.94 (0.86 to 1.04) for men and 0.88 (0.80 to 0.97) for women, respectively. The proportions mediated by general and central obesity were 51.00% and 68.04% for men, while for women the proportions were 48.58% and 32.58%, respectively. Furthermore, NAFLD patients with lower educational attainment showed an incremental increased risk of advanced fibrosis in both genders.

Conclusions

: In China, a low education level was associated with a higher risk of prevalent NAFLD in women, as well as high probability of fibrosis in both genders.

Triglyceride glucose index as a predictor for non-alcoholic fatty liver disease: insights from a longitudinal analysis in non-obese individuals

Background

A substantial portion of non-obese population is afflicted with Non-alcoholic Fatty Liver Disease (NAFLD). The Triglyceride Glucose (TyG) index, a quantifier of insulin resistance magnitude, is determined by the product of fasting plasma glucose and triglyceride concentrations. The relationship between the TyG index and NAFLD within this cohort remains ambiguous.

Methods

We conducted a retrospective analysis utilizing datasets acquired from the Dryad digital repository. Non-obese participants (BMI < 25 kg/m2) were enrolled at the Wenzhou Medical Center of Wenzhou People's Hospital between January 2010 and December 2014. Demographic information and biochemical parameters were systematically compiled, and the diagnosis of NAFLD was established through ultrasonographic evidence.

Results

This study cohort included 16,172 non-obese participants with a 5-year follow-up, among whom 2,322 (14.36%) developed NAFLD. The disparity between TyG index quartiles in the accumulative incidence of new-onset NAFLD was distinct, with an increasing risk of new-onset NAFLD as the TyG index increased. Participants in highest quartile exhibited the maximum risk of NAFLD. In the fully adjusted model 3, the hazard ratios for NAFLD in Q2, Q3, and Q4 were 2.15 (1.62, 2.87), 2.89 (2.20, 3.80) and 4.58 (3.48, 6.02), respectively. Meanwhile, the TyG index and NAFLD risk showed a highly significant overall correlation (p < 0.0001) and nonlinearity (p < 0.0001) according to the limited cubic splines. In subgroup analysis, a significant interaction was noted between new-onset NAFLD and SBP (<140 mmHg vs. ≥140 mmHg; P for interaction = 0.0114). The SBP < 140 mmHg subgroup demonstrated an enhanced TyG index influence on NAFLD risk (HR = 2.83, 95% CI: 2.48-3.23, p < 0.0001).

Conclusion

The TyG index serves as a straightforward instrument for assessing NAFLD risk in non-obese individuals, enabling prompt identification and management in this population segment.

Long-term outcomes in lean and non-lean NAFLD patients: a systematic review and meta-analysis

BACKGROUND

Although nonalcoholic fatty liver disease (NAFLD) commonly occurs in overweight or obese individuals, it is increasingly being identified in the lean population. The association between lean and an increased risk of all-cause mortality among patients with NAFLD remains controversial. We aimed to perform a systematic review and meta-analysis of the literature to evaluate this association and compare the long-term outcomes of lean NAFLD patients and non-lean NAFLD patients.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Wan Fang, and Chinese Biomedical Literature Database (CBM) from inception to October 15, 2021, for relevant original research articles without any language restrictions. Our primary outcome was to compare the all-cause mortality in lean NAFLD patients and non-lean NAFLD patients by qualitative synthesis. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random effect model. Heterogeneity was evaluated using I-squared (I²) statistics while publication bias was determined using Egger's tests. Subgroup and sensitivity analyses were performed. As for secondary outcomes, we estimated total, cardiovascular, and liver-related mortality, as well as the incidence of diabetes, hypertension, cirrhosis, and cancer in lean and non-lean individuals with NAFLD by quantitative synthesis. Person-years of follow-up were used as the denominator to estimate the mortality and incidence.

RESULTS

We identified 12 studies (n = 26,329), 7 of which (n = 7924) were used to evaluate the risk of all-cause mortality between lean and non-lean NAFLD patients. Lean patients with NAFLD were found to be at an elevated risk of death compared to non-lean patients (RR = 1.39, 95% CI 1.08-1.82, heterogeneity: I² = 43%). Among the lean NAFLD population, all-cause mortality was 13.3 (95% CI: 6.7-26.1) per 1000 person-years, 3.6 (95% CI: 1.0-11.7) for liver-related mortality, and 7.7 (95% CI: 6.4-9.2) for cardiovascular-related mortality. The incidence of new-onset diabetes was 13.7 (95% CI 8·2-22.7) per 1000 person-years, new-onset hypertension was 56.1 (95% CI: 40.2-77.9), cirrhosis was 2.3 (95% CI: 1.0-5.0), and cancer was 25.7 (95% CI: 20.3-32.4).

CONCLUSIONS

Lean patients with NAFLD had a higher risk of all-cause death than non-lean patients. Body mass index (BMI) should not be used as a criterion to determine whether further observation and therapy of patients with NAFLD are warranted.

Disease severity and antiviral response in patients with chronic hepatitis B with non-obese NAFLD

BACKGROUND

The burden of nonalcoholic fatty liver disease (NAFLD) is growing in patients with chronic hepatitis B (CHB). NAFLD is typically associated with obesity, however, it is increasingly being identified in non-obese patients. This study aimed to investigate disease severity and antiviral response in non-obese patients with CHB with NAFLD (CHB + NAFLD).

METHODS

A total of 809 patients with CHB + NAFLD were prospectively recruited and followed up for 3 years. NAFLD was diagnosed by transient elastography and defined as controlled attenuation parameter ≥248 dB/m, in the absence of excessive alcohol intake. Obesity status was defined by the Asian body mass index (BMI) cutoff of 25 kg/m2. Metabolic abnormality was defined by the presence of dyslipidemia, hypertension or diabetes. Fibrosis staging was defined according to the EASL-ALEH guidelines, with fibrosis progression defined as ≥1-stage increment.

RESULTS

In the total cohort (median age 40 years, 59.0% antiviral-treated), 33.3% were non-obese. Non-obese patients were less metabolically abnormal than obese patients (60.2% vs 72.0%, P = 0.003). After 3-year follow up, the rate of fibrosis progression was comparable between non-obese and obese patients (17.5% vs 21.9% in the total cohort, P = 0.145; 15.7% vs 14.6% in antiviral-treated cohort with persistent viral suppression, P = 0.795). No significant differences in virological and biochemical responses were observed between non-obese and obese patients (P >0.05 for all).

CONCLUSION

Approximately one third of CHB + NAFLD patients were non-obese. Non-obese patients, while less metabolically abnormal, had a similar risk for fibrosis progression as obese patients. Obesity status did not impact the efficiency of antiviral therapy.

Use of Machine Learning to Predict Onset of NAFLD in an All-Comers Cohort-Development and Validation in 2 Large Asian Cohorts

Background and Aims

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases. There are no universally accepted models that accurately predict time to onset of NAFLD. Machine learning (ML) models may allow prediction of such time-to-event (ie, survival) outcomes. This study aims to develop and independently validate ML-derived models to allow personalized prediction of time to onset of NAFLD in individuals who have no NAFLD at baseline.

Methods

The development dataset comprised 25,599 individuals from a South Korean NAFLD registry. A random 70:30 split divided it into training and internal validation sets. ML survival models (random survival forest, extra survival trees) were fitted, with time to NAFLD diagnosis in months as the target variable and routine anthropometric and laboratory parameters as predictors. The independent validation dataset comprised 16,173 individuals from a Chinese open dataset. Models were evaluated using the concordance index (c-index) and Brier score on both the internal and independent validation sets.

Results

The datasets (development vs independent validation) had 1,331,107 vs 543,874 person months of follow-up, NAFLD incidence of 25.7% (6584 individuals) vs 14.4% (2322 individuals), and median time to NAFLD onset of 60 (interquartile range 38-75) vs 24 (interquartile range 13-37) months, respectively. The ML models achieved a good c-index of >0.7 in the validation cohort-random survival forest 0.751 (95% confidence interval 0.742-0.759), extra survival trees 0.752 (95% confidence interval 0.744-0.762).

Conclusion

ML models can predict time-to-onset of NAFLD based on routine patient data. They can be used by clinicians to deliver personalized predictions to patients, which may facilitate patient counseling and clinical decision making on interval imaging timing.

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.

Cardiovascular morbidity and mortality in lean vs. non-lean MASLD: A comprehensive meta-analysis

BACKGROUND

Lean metabolic dysfunction-associated steatotic liver disease (MASLD), characterized by a BMI < 25 kg/m² (or < 23 kg/m² in Asians), presents a challenging prognosis compared to non-lean MASLD. This study examines cardiovascular outcomes in both lean and non-lean MASLD cohorts.

METHODS

In this meta-analysis, pooled odds ratios (ORs) within 95 % confidence intervals (CIs) were calculated for primary outcomes (cardiovascular mortality and major adverse cardiovascular events [MACE]) and secondary outcomes (cardiovascular disease [CVD], all-cause mortality, hypertension, and dyslipidemia). Studies comparing lean and non-lean MASLD within the same cohorts were analyzed, prioritizing those with larger sample sizes or recent publication dates.

RESULTS

Twenty-one studies were identified, encompassing lean MASLD patients (n = 7153; mean age 52.9 ± 7.4; 56 % male) and non-lean MASLD patients (n = 23,514; mean age 53.2 ± 6.8; 63 % male). Lean MASLD exhibited a 50 % increase in cardiovascular mortality odds compared to non-lean MASLD (OR: 1.5, 95 % CI 1.2-1.8; p < 0.0001). MACE odds were 10 % lower in lean MASLD (OR: 0.9, 95 % CI 0.7-1.2; p = 0.7), while CVD odds were 40 % lower (p = 0.01). All-cause mortality showed a 40 % higher odds in lean MASLD versus non-lean MASLD (p = 0.06). Lean MASLD had 30 % lower odds for both hypertension (p = 0.01) and dyslipidemia (p = 0.02) compared to non-lean MASLD.

CONCLUSION

Despite a favorable cardiometabolic profile and comparable MACE rates, lean individuals with MASLD face elevated cardiovascular mortality risk.

Natural history of lean and non-lean metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Conflicting evidence regarding the prognosis of lean metabolic dysfunction-associated steatotic liver disease (MASLD) has raised substantial questions.

AIM

This study aimed to elucidate the prognosis of lean MASLD by conducting a comprehensive analysis of a vast Asian cohort.

METHODS

This study used a nationwide, population-based database and analyzed 2.9 million patients. The primary endpoints were liver-related events (LREs) and cardiovascular events (CVEs) in patients with lean MASLD, non-lean MASLD, and normal liver control groups.

RESULTS

The median observation period was 4.2 years. The 5-year incidence values of LREs in the lean MASLD, non-lean MASLD, and normal liver control groups were 0.065%, 0.039%, and 0.006%, respectively. The LRE risk of lean MASLD was significantly higher than that of normal liver control (adjusted hazard ratio [aHR]: 5.94, 95% confidence interval [CI]: 3.95-8.92) but comparable to that of non-lean MASLD (aHR: 1.35, 95% CI: 0.87-2.08). By contrast, for CVEs, the non-lean MASLD group exhibited a higher 5-year cumulative incidence rate (0.779%) than the lean MASLD (0.600%) and normal liver control (0.254%) groups. The lean MASLD group had a reduced risk of CVEs compared with the non-lean MASLD group (aHR, 0.73; 95% CI: 0.64-0.84), and comparable risk of CVEs to the normal liver control group (aHR, 0.99; 95% CI: 0.88-1.12).

CONCLUSION

Lean MASLD exhibits a similar LRE risk and a lower CVE risk to non-lean MASLD. Therefore, follow-up and treatment strategies should be tailored to the specific MASLD condition.

Disparities among ethnic groups in mortality and outcomes among adults with MASLD: A multicenter study

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver disease and 10%-20% occurs in lean individuals. There is little data in the literature regarding outcomes in an ethnically-diverse patient populations with MASLD. Thus, we aim to investigate the natural history and ethnic disparities of MASLD patients in a diverse population, and stratified by body mass index categories.

METHODS

We conducted a retrospective multicenter study on patients with MASLD at the Banner Health System from 2012 to 2022. Main outcomes included mortality and incidence of cirrhosis, cardiovascular disease, diabetes mellitus (DM), liver-related events (LREs), and cancer. We used competing risk and Cox proportional hazard regression analysis for outcome modelling.

RESULTS

A total of 51 452 (cross-sectional cohort) and 37 027 (longitudinal cohort) patients were identified with 9.6% lean. The cohort was 63.33% European ancestry, 27.96% Hispanic ancestry, 3.45% African ancestry, and 2.31% Native American/Alaskan ancestry. Median follow-up was 45.8 months. After adjusting for confounders, compared to European individuals, Hispanic and Native American/Alaskan patients had higher prevalence of cirrhosis and DM, and individuals of Hispanic, African, and Native American/Alaskan ancestry had higher mortality and incidence of LREs and DM. Lean patients had higher mortality and incidence of LREs compared with non-lean patients.

CONCLUSION

Native American/Alaskan, Hispanic, and African patients had higher mortality and incidence of LREs and DM compared with European patients. Further studies to explore the underlying disparities and intervention to prevent LREs in lean patients, particularly several ethnic groups, may improve clinical outcomes.

MAFLD: an ideal framework for understanding disease phenotype in individuals of normal weight

The prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) is significant, impacting almost one-third of the global population. MAFLD constitutes a primary cause of end-stage liver disease, liver cancer and the need for liver transplantation. Moreover, it has a strong association with increased mortality rates due to various extrahepatic complications, notably cardiometabolic diseases. While MAFLD is typically correlated with obesity, not all individuals with obesity develop the disease and a significant percentage of MAFLD occurs in patients without obesity, termed lean MAFLD. The clinical features, progression and underlying physiological mechanisms of patients with lean MAFLD remain inadequately characterized. The present review aims to provide a comprehensive summary of current knowledge on lean MAFLD and offer a perspective on defining MAFLD in individuals with normal weight. Key to this process is the concept of metabolic health and flexibility, which links states of dysmetabolism to the development of lean MAFLD. This perspective offers a more nuanced understanding of MAFLD and its underlying mechanisms and highlights the importance of considering the broader metabolic context in which the disease occurs. It also bridges the knowledge gap and offers insights that can inform clinical practice.

Lean non-alcoholic fatty liver disease and the risk of all-cause mortality: An updated meta-analysis

INTRODUCTION AND OBJECTIVES

Cohort studies reported controversial results regarding the long-term prognosis of patients with lean non-alcoholic fatty liver disease (NAFLD) compared to non-lean NAFLD patients. This updated meta-analysis aimed to estimate the magnitude of the association between lean body mass index and all-cause mortality risk in NAFLD patients.

MATERIALS AND METHODS

We systematically searched the EMBASE and MEDLINE databases from inception to March 2023 to identify observational studies that reported hazard ratio (HR) for all-cause mortality of patients with lean NAFLD versus those with non-lean, overweight, or obese NAFLD. Multivariable-adjusted hazard ratios (HRs) for all-cause mortality were pooled using a random effects model.

RESULTS

Fourteen studies with 94,181 NAFLD patients (11.3 % with lean NAFLD) and 7,443 fatal events over a median follow-up of 8.4 years (IQR, 6.6-17.4 years) were included. Patients with lean NAFLD had a higher risk of all-cause mortality than those with non-lean NAFLD (random-effects HR 1.61, 95 % CI 1.37-1.89; I2=77 %). The magnitude of this risk remained unchanged even after stratified analysis by measures of NAFLD diagnosis, study country, cohort setting, length of follow-up, adjustment with fibrosis stage/cirrhosis, and the Newcastle-Ottawa Scale. The risk was independent of age, sex, and cardiometabolic risk factors. Sensitivity analyses did not alter these findings. The funnel plot and Egger's test revealed no significant publication bias.

CONCLUSIONS

This meta-analysis revealed that lean NAFLD is associated with an approximately 1.6-fold increased mortality risk. Further studies are needed to unravel the existing but complex link between lean NAFLD and an increased risk of death.

Gut microbiota in MAFLD: therapeutic and diagnostic implications

Metabolic dysfunction-associated fatty liver disease (MAFLD), formerly known as nonalcoholic fatty liver disease, is becoming a significant contributor to chronic liver disease globally, surpassing other etiologies, such as viral hepatitis. Prevention and early treatment strategies to curb its growing prevalence are urgently required. Recent evidence suggests that targeting the gut microbiota may help treat and alleviate disease progression in patients with MAFLD. This review aims to explore the complex relationship between MAFLD and the gut microbiota in relation to disease pathogenesis. Additionally, it delves into the therapeutic strategies targeting the gut microbiota, such as diet, exercise, antibiotics, probiotics, synbiotics, glucagon-like peptide-1 receptor agonists, and fecal microbiota transplantation, and discusses novel biomarkers, such as microbiota-derived testing and liquid biopsy, for their diagnostic and staging potential. Overall, the review emphasizes the urgent need for preventive and therapeutic strategies to address the devastating consequences of MAFLD at both individual and societal levels and recognizes that further exploration of the gut microbiota may open avenues for managing MAFLD effectively in the future.

Natural history of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), which has been the term for non-alcoholic fatty liver disease (NAFLD) since June 2023, represents the most common liver disease worldwide and is a leading cause of liver-related morbidity and mortality. A thorough knowledge of the disease's natural history is required to promptly stratify patients' risks, since MASLD is a multifaceted disorder with a broad range of clinical phenotypes. The histological disease spectrum ranges from isolated hepatic steatosis, currently named as metabolic dysfunction-associated steatotic liver (MASL), to metabolic dysfunction-associated steatohepatitis (MASH) and eventually may accumulate hepatic fibrosis and develop cirrhosis and/or hepatocellular carcinoma (HCC). Several risk factors for fibrosis progression have been identified, while the disease's progression displays notable dynamism and bidirectionality. When compared to the general population, all MASLD histological stages are substantially related with greater overall mortality, and this association exhibits a disease severity-dependent pattern. Interestingly, the fibrosis stage is the most accurate predictor of mortality among MASLD patients. The mortality attributed to MASLD predominantly stems from issues linked with the liver and cardiovascular system, as well as HCC and extrahepatic cancers. In light of the disease natural course, it is crucial to prioritize the identification of at-risk patients for disease progression in order to effectively address and change modifiable risk factors, hence mitigating disease complications. Further investigation is required to define the phenotype of rapid progressors more precisely as well as to improve risk stratification for HCC in non-cirrhotic individuals.

Genetics of liver disease in adults

Chronic liver disease stands as a significant global health problem with an estimated 2 million annual deaths across the globe. Combining the use of next-generation sequencing technologies with evolving knowledge in the interpretation of genetic variation across the human genome is propelling our understanding, diagnosis, and management of both rare and common liver diseases. Here, we review the contribution of risk and protective alleles to common forms of liver disease, the rising number of monogenic diseases affecting the liver, and the role of somatic genetic variants in the onset and progression of oncological and non-oncological liver diseases. The incorporation of genomic information in the diagnosis and management of patients with liver disease is driving the beginning of a new era of genomics-informed clinical hepatology practice, facilitating personalized medicine, and improving patient care.

Update in lean metabolic dysfunction-associated steatotic liver disease

BACKGROUND

A new nomenclature consensus has emerged for liver diseases that were previously known as non-alcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD). They are now defined as metabolic dysfunction-associated steatotic liver disease (MASLD), which includes cardiometabolic criteria in adults. This condition, extensively studied in obese or overweight patients, constitutes around 30% of the population, with a steady increase worldwide. Lean patients account for approximately 10%-15% of the MASLD population. However, the pathogenesis is complex and is not well understood.

AIM

To systematically review the literature on the diagnosis, pathogenesis, characteristics, and prognosis in lean MASLD patients and provide an interpretation of these new criteria.

METHODS

We conducted a comprehensive database search on PubMed and Google Scholar between January 2012 and September 2023, specifically focusing on lean NAFLD, MAFLD, or MASLD patients. We include original articles with patients aged 18 years or older, with a lean body mass index categorized according to the World Health Organization criteria, using a cutoff of 25 kg/m2 for the general population and 23 kg/m2 for the Asian population.

RESULTS

We include 85 studies in our analysis. Our findings revealed that, for lean NAFLD patients, the prevalence rate varied widely, ranging from 3.8% to 34.1%. The precise pathogenesis mechanism remained elusive, with associations found in genetic variants, epigenetic modifications, and adaptative metabolic response. Common risk factors included metabolic syndrome, hypertension, and type 2 diabetes mellitus, but their prevalence varied based on the comparison group involving lean patients. Regarding non-invasive tools, Fibrosis-4 index outperformed the NAFLD fibrosis score in lean patients. Lifestyle modifications aided in reducing hepatic steatosis and improving cardiometabolic profiles, with some medications showing efficacy to a lesser extent. However, lean NAFLD patients exhibited a worse prognosis compared to the obese or overweight counterpart.

CONCLUSION

MASLD is a complex disease comprising epigenetic, genetic, and metabolic factors in its pathogenesis. Results vary across populations, gender, and age. Limited data exists on clinical practice guidelines for lean patients. Future studies employing this new nomenclature can contribute to standardizing and generalizing results among lean patients with steatotic liver disease.

Association between alanine aminotransferase to high-density lipoprotein cholesterol ratio and nonalcoholic fatty liver disease: a retrospective cohort study in lean Chinese individuals

There is limited research on the association between the alanine aminotransferase to high-density lipoprotein cholesterol ratio (ALT/HDL-C) ratio and nonalcoholic fatty liver disease (NAFLD). The purpose of the current research was to look into the connection between the ALT/HDL-C ratio and the risk of NAFLD in lean Chinese individuals. Between January 2010 and December 2014, 11,975 non-obese people participated in this prospective cohort research. The relationship between the ALT/HDL-C ratio and the risk of developing NAFLD was assessed using the Cox proportional-hazards regression model, Cox proportional hazards regression with cubic spline functions and smooth curve fitting, sensitivity analysis, and subgroup analyses. The ALT/HDL-C ratio's potential value as a NAFLD prognostic marker was to be evaluated using the receiver operating characteristic curve analysis. A total of 5419 (45.253%) women comprised the research's participant population, and the research participants' average age was 43.278 ± 14.941 years. The ALT/HDL-C ratio was 11.607 (7.973-17.422) at the median (interquartile ranges). 2087 (17.428%) patients had NAFLD diagnoses throughout a median follow-up of 24.967 months. The study's findings demonstrated a positive connection between the ALT/AHDL-C ratio and the incident NAFLD (HR = 1.037, 95% CI: 1.031-1.042) when adjusting for relevant factors. The ALT/HDL-C ratio and NAFLD risk had a nonlinear connection, with 12.963 as the ratio's inflection point. Effect sizes (HR) were 1.023 (95% CI: 1.017-1.029) and 1.204 (95% CI: 1.171-1.237), respectively, on the right and left sides of the inflection point. The sensitivity analysis also showed how reliable our findings were. According to subgroup analysis, those with BMI < 24 kg/m2 and DBP < 90 mmHg had a stronger correlation between the ALT/HDL-C ratio and NAFLD risk. The current study shows a positive and non-linear connection between the ALT/HDL-C ratio and NAFLD risk in lean Chinese individuals. When the ALT/HDL-C ratio is less than 12.963, it is significantly linked to NAFLD. Therefore, from a therapy standpoint, it is advised to keep the ALT/HDL-C ratio less than the inflection point.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

Association between the ZJU index and risk of new-onset non-alcoholic fatty liver disease in non-obese participants: a Chinese longitudinal prospective cohort study

Background

Non-alcoholic fatty liver disease (NAFLD) is increasingly observed in non-obese individuals. The ZJU (Zhejiang University) index has been established as a new and efficient tool for detecting NAFLD, but the relationship between the ZJU index and NAFLD within non-obese individuals still remains unclear.

Methods

A post-hoc evaluation was undertaken using data from a health assessment database by the Wenzhou Medical Center. The participants were divided into four groups based on the quartile of the ZJU Index. Cox proportional hazards regression, Kaplan-Meier analysis and tests for linear trends were used to evaluate the relationship between the ZJU index and NAFLD incidence. Subgroup analysis was conducted to test the consistency of the correlation between ZJU and NAFLD in subsgroups. Receiver operative characteristic (ROC) curve analysis was performed to evaluate the predictive performance of the ZJU index, compared with the Atherogenic index of plasma (AIP) and Remnant lipoprotein cholesterol (RLP-C) index.

Results

A total of 12,127 were included in this study, and 2,147 participants (17.7%) developed NAFLD in 5 years follow-up. Participants in higher ZJU quartiles tended to be female and have higher liver enzymes (including ALP, GGT, ALT, AST), GLU, TC, TG, LDL and higher NAFLD risk. Hazard Ratios (HR) and 95% confidence intervals (CI) for new-onset NAFLD in Q2, Q3, and Q4 were 3.67(2.43 to 5.55), 9.82(6.67 to 14.45), and 21.67(14.82 to 31.69) respectively in the fully adjusted model 3. With increased ZJU index, the cumulative new-onset NAFLD gradually increased. Significant linear associations were observed between the ZJU index and new-onset NAFLD (p for trend all<0.001). In the subgroup analysis, we noted a significant interaction in sex, with HRs of 3.27 (2.81, 3.80) in female and 2.41 (2.21, 2.63) in male (P for interaction<0.01). The ZJU index outperformed other indices with an area under the curve (AUC) of 0.823, followed by AIP (AUC=0.747) and RLP-C (AUC=0.668).

Conclusion

The ZJU index emerges as a promising tool for predicting NAFLD risk in non-obese individuals, outperforming other existing parameters including AIP and RLP-C. This could potentially aid in early detection and intervention in this specific demographic.

Association of BMI with mortality in drug-induced liver injury

BACKGROUND

To clarify the associations between BMI and the incidences of all-cause death or liver-related death (LRD)/liver transplantation (LT) in drug-induced liver injury (DILI).

METHODS

DILI patients from three hospitals were retrospectively retrieved and follow-up from 2009 to 2021. They were categorized into underweight (BMI < 18.5 kg/m 2 ), normal weight (BMI of 18.5-23.9 kg/m 2 ), overweight (BMI of 24-27.9 kg/m 2 ) and obese (BMI ≥ 28 kg/m 2 ) groups. Cox regression models were conducted to reveal the effect of BMI on all-cause death or LRD/LT.

RESULTS

A total of 1469 eligible DILI patients were included: underweight 73 (4.97%), normal weight 811 (55.21%), overweight 473 (32.20%) and obese 112 (7.62%). Eighty-nine patients (6.06%) had all-cause death, of which 66 patients (4.49%) had LRD/LT. The median age was 52 years old, and females were 1039 (70.73%). The associations between BMI and all-cause mortality ( nonlinear test P <  0.01) or liver-related mortality/LT ( nonlinear test P  = 0.01) were J-shaped. Multivariate Cox regression analysis showed that underweight (HR: 3.02, 95% CI: 1.51-6.02) was significantly associated with all-cause mortality after adjusting for age and sex. Furthermore, obese males were significantly associated with liver-related mortality/LT (HR: 3.49, 95% CI: 1.13-10.72) after additional adjustment for serological indices and comorbidities.

CONCLUSION

Association between BMI and mortality is a J-shape. The overall mortality was significantly higher in underweight and obese group. Male obesity is independently associated with LRD/LT. These findings indicate that DILI patients with extreme BMI would have a high risk of dismal outcomes, which warrants extra medical care.

Risk Stratification of Advanced Fibrosis in Patients With Human Immunodeficiency Virus and Hepatic Steatosis Using the Fibrosis-4, Nonalcoholic Fatty Liver Disease Fibrosis, and BARD Scores

Background

Nonalcoholic fatty liver disease (NAFLD) and subsequent progression to fibrosis is increasingly prevalent in people with HIV (PWH). We used noninvasive methods to stratify risk and identify associated factors of advanced fibrosis in PWH with NAFLD.

Methods

We conducted a retrospective study of PWH in our clinic from 2005 to 2022. We used liver imaging or biopsy reports to identify cases of hepatic steatosis after excluding specified etiologies. We used the Fibrosis-4 (FIB-4), NAFLD Fibrosis (NFS), and body mass index, aspartate transaminase/alanine transaminase ratio, and diabetes score scores to stratify fibrosis. We used logistic regression to identify factors associated with advanced fibrosis.

Results

Among 3959 PWH in care, 1201 had available imaging or liver biopsies. After exclusions, 114 of 783 PWH had evidence of hepatic steatosis (14.6%). Most were male (71.1%), with a median age of 47 years, and median body mass index of 30.1 kg/m2. Approximately 24% had lean NAFLD (ie, body mass index < 25 kg/m2). Based on the FIB-4 and NFS, 34 (29.8%) and 36 (31.6%) had advanced fibrosis, whereas 1 in 4 had low risk of fibrosis based on FIB-4, NFS, and BARD scores. In adjusted analysis using FIB-4, advanced fibrosis was associated with age > 45 years (adjusted odds ratio, 6.29; 95% confidence interval, 1.93-20.50) and hypoalbuminemia (adjusted odds ratio, 9.45; 95% confidence interval, 2.45-32.52) in addition to elevated transaminases and thrombocytopenia, whereas using the NFS did not identify associations with advanced fibrosis.

Conclusions

We found 14.6% of PWH had NAFLD, with 1 in 3 having advanced fibrosis. Our study provides practical insights into fibrosis risk stratification in HIV primary care settings.

Association of Uric Acid to Creatinine Ratio with Metabolic Dysfunction-Associated Fatty Liver in Non-Obese Individuals Without Type 2 Diabetes Mellitus

INTRODUCTION

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease, which is usually associated with type 2 diabetes mellitus (T2DM) and obesity. However, the incidence of MALFD in non-obese individuals without T2DM is increasing, and the pathogenesis is unclear. Serum uric acid to creatinine ratio (sUA/Cr) can reflect overall metabolic status. This study aims to observe the association between sUA/Cr and MAFLD in non-obese individuals without T2DM.

METHODS

A total of 21,996 individuals were included in this study. The subjects were divided into four subgroups: non-obese patients without T2DM, obese patients without T2DM, non-obese patients with T2DM, and obese patients with T2DM. Logistic regression analyzed the correlation between sUA/Cr and MAFLD subgroups. Receiver operating characteristics analyzed the predictive value of sUA/Cr for MAFLD subgroups. The stratified analyses by sex and age were performed.

RESULTS

Non-obese MAFLD individuals without T2DM had higher sUA/Cr levels than their counterparts. sUA/Cr was significantly correlated positively with MAFLD in non-obese patients. Similar results were observed in both males and females and in populations at all age stages (all p<0.01). sUA/Cr was capable of discriminating MAFLD in non-obese individuals without T2DM (AUC: 0.667), especially for patients over 60 years old (AUC: 0.704).

CONCLUSION

The sUA/Cr ratio was correlated with MAFLD in non-obese patients without T2DM. The predictive value of sUA/Cr for MAFLD was observed. Hence, the sUA/Cr ratio might be given more concern for the risk of MAFLD in non-obese individuals without T2DM.

What Is New in Metabolic Dysfunction-Associated Steatotic Liver Disease in Lean Individuals: From Bench to Bedside

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects more than 30% of the world's adult population. While it is associated with obesity and metabolic syndrome, emerging evidence has shown that a substantial number of MASLD patients have a normal body mass index ("lean individuals with MASLD"). In this article, we provide an overview of the definition, epidemiology, pathogenesis, and clinical outcomes associated with lean individuals with MASLD and updates on current management.

Association between physical activity and diet quality of obese and non-obese MAFLD

BACKGROUND AND AIM

Clinical data on the prevalence of metabolic-associated fatty liver disease (MAFLD) in obese and non-obese individuals within a diverse US population is scarce. Furthermore, the influence of physical activity (PA) and dietary quality (DQ) on MAFLD risk remains unclear. This study aims to assess the prevalence and clinical features of MAFLD and examine the relationship between PA and DQ with the risk of developing MAFLD.

METHODS AND RESULTS

A cross-sectional analysis of data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES) was conducted. The overall MAFLD prevalence was 41.9%, with 28.6% of participants being obese and 13.4% non-obese. Among those with MAFLD, 67.1% (95% confidence interval (CI): 59.1%-75.1%) were obese, and 32.9% (95% CI: 29.1%-36.7%) were non-obese. Non-obese MAFLD was more frequent in Asians (27.2%), while obese MAFLD was more prevalent in Blacks (66.3%). Metabolic comorbidities were more common in individuals with obese MAFLD, who also exhibited more advanced fibrosis. A high-quality diet (HQD) and increased PA were linked to reduced odds of both obese and non-obese MAFLD (odds ratio (OR) and 95% CI: 0.67 [0.51-0.88] and 0.57 [0.47-0.69]; 0.62 [0.43-0.90] and 0.63 [0.46-0.87], respectively). PA and HQD significantly decreased the risk of obese and non-obese MAFLD (OR and 95% CI: 0.46 [0.33-0.64] and 0.42 [0.31-0.57]).

CONCLUSION

A substantial proportion of the US population is affected by both obese and non-obese MAFLD. A strong association exists between a lower risk of both types of MAFLD and adherence to an HQD and engagement in PA.

The interplay of metabolic dysfunction-associated fatty liver disease and viral hepatitis on liver disease severity: A large community-based study in a viral endemic area

BACKGROUND AND AIM

The prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) and its interplay with hepatitis B virus (HBV) and hepatitis C virus (HCV) in terms of liver disease severity is elusive.

METHODS

A mass surveillance program was conducted in a viral hepatitis endemic area. The objective was to identify MAFLD/non-MAFLD subjects with advanced liver disease.

RESULTS

Two thousand two hundred and forty-two (41.7%) of the 5378 subjects were identified as having MAFLD, and 375 (7.0%) had advanced liver disease. The proportions of anti-HCV and HBsAg seropositivity were 19.3% and 9.7%, respectively. The proportions of advanced fibrosis in subjects with non-viral hepatitis (NBNC), HBV and HCV infection were 2.8%, 5.7% and 23.4%, respectively. Subjects with MAFLD had a significantly higher proportion of advanced fibrosis (8.7% vs 5.7%, P < 0.001). Factors associated with advanced fibrosis included age (odds ratio [OR]/95% confidence interval [CI]: 4.8/3.7-6.0, P < 0.001), male sex (OR/CI: 1.3/1.0-1.7, P = 0.019), anti-HCV seropositivity (OR/CI: 5.9/4.6-7.5, P = 0.019), MAFLD-lean metabolic dysregulation (MS) (OR/CI: 2.6/1.3-5.2, P = 0.005; compared with the non-MAFLD group) and MAFLD-diabetes (OR/CI: 1.5/1.1-2.1, P = 0.008; compared with the non-MAFLD group). MAFLD did not aggravate liver disease severity in patients with viral hepatitis. However, among NBNC subjects, factors associated with advanced liver disease included MAFLD-lean MS group (OR/CI: 9.1/2.4-34.6, P = 0.001; compared with non-MAFLD group) and MAFLD-DM group (OR/CI: 2.0/1.2-3.2, P = 0.004; compared with non-MAFLD group).

CONCLUSIONS

MAFLD patients with diabetes and metabolic dysregulation had a higher risk of advanced liver disease. The effect was more significant in non-viral hepatitis subjects in a community level.

Gastrointestinal cancers in lean individuals with non-alcoholic fatty liver disease: A systematic review and meta-analysis

BACKGROUND & AIMS

Obesity and non-alcoholic fatty liver disease (NAFLD) are known risk factors for gastrointestinal (GI) cancers. However, GI carcinogenesis in lean NAFLD patients remains unclear. This systematic review and meta-analysis aims to investigate the association between lean NAFLD and GI cancer risk.

METHODS

PubMed, Embase and Cochrane Library databases were systematically searched (from inception date to April 2023) for cohort studies assessing GI cancers in lean (body mass index [BMI] < 25 kg/m2 or < 23 kg/m2 in Asians) and non-lean (BMI ≥25 kg/m2 or ≥ 23 kg/m2 in Asians) NAFLD individuals. Data from eligible studies were extracted, and meta-analysis was carried out using a random effects model to obtain risk ratios (RRs) with 95% confidence intervals (CIs). Subgroup analyses, meta-regressions and sensitivity analyses were also performed. This study was registered in PROSPERO (CRD42023420902).

RESULTS

Eight studies with 56,745 NAFLD individuals (11% were lean) and 704 cases of incident GI cancers were included. Lean NAFLD was associated with higher risk of hepatic (RR 1.77, 95% CI 1.15-2.73), pancreatic (RR 1.97, 95% CI 1.01-3.86) and colorectal cancers (RR 1.53, 95% CI 1.12-2.09), compared to non-lean NAFLD. No significant differences were observed for oesophagus, gastric, biliary and small intestine cancers.

CONCLUSIONS

This study shows that lean NAFLD patients have an increased risk of liver, pancreatic and colorectal cancers compared to non-lean NAFLD patients, emphasizing the need to explore tailored cancer prevention strategies for this specific patient group. Further research is required to explore the mechanisms underlying the association between lean NAFLD and specific GI cancers.

Hepatic steatosis in people older and younger than fifty who are living with HIV and HIV-negative controls: A cross-sectional study nested within the POPPY cohort

BACKGROUND

Hepatic steatosis is a major cause of chronic liver disease associated with several negative health outcomes. We compared the prevalence of and factors associated with steatosis in people living with and without HIV.

METHODS

Older (>50 years) and younger (<50 years) people with HIV and older HIV-negative controls (>50 years) underwent liver transient elastography examination with controlled attenuation parameter (steatosis ≥238 dB/m, moderate/severe steatosis ≥280 dB/m, liver fibrosis ≥7.1 kPa). We compared groups using logistic regression/Chi-squared/Fisher's exact/Kruskal-Wallis tests.

RESULTS

In total, 317 participants (109 older people with HIV; 101 younger people with HIV; 107 HIV-negative controls) were predominantly white (86%) and male (76%), and 21% were living with obesity (body mass index ≥30 kg/m2 ). Most (97%) people with HIV had undetectable HIV RNA. The prevalence of fibrosis was 8.4%, 3.0%, and 6.5% in the three groups, respectively (p = 0.26). Fibrosis was predominately (>65%) mild. The prevalence of steatosis was the same in older people with HIV (66.4%) and controls (66.4%) but lower in younger people with HIV (37.4%; p < 0.001). After adjustment, younger people with HIV were less likely to have steatosis (odds ratio [OR] 0.26; 95% confidence interval [CI] 0.14-0.52) than controls, but male sex (OR 2.45; 95% CI 1.20-4.50) and high waist-to-hip ratio (OR 3.04; 95% CI 1.74-5.33) were associated with an increased odds of steatosis. We found no association between steatosis and HIV-related variables.

CONCLUSIONS

The prevalence of hepatic steatosis and fibrosis was similar between older participants regardless of HIV status. Age, sex, and abdominal obesity, but not HIV-related variables, were associated with steatosis. Interventions for controlling obesity should be integrated into routine HIV care.

Mechanisms and Therapeutic Strategies for MAFLD Targeting TLR4 Signaling Pathways

BACKGROUND

Metabolic-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases. The underlying pathophysiological mechanisms are intricate and involve various factors. Unfortunately, there is currently a lack of available effective treatment options. Toll-like receptors (TLRs) are a group of pattern-recognition receptors that are responsible for activating the innate immune system. Research has demonstrated that TLR4 plays a pivotal role in the progression of MAFLD by facilitating the pathophysiological mechanisms.

SUMMARY

Lipid peroxidation, pro-inflammatory factors, insulin resistance (IR), and dysbiosis of intestinal microbiota are considered as the pathogenic mechanisms of MAFLD. This review summarizes the impact of TLR4 signaling pathways on the progression of MAFLD, specifically in relation to lipid metabolic disorders, IR, oxidative stress, and gut microbiota disorders. Additionally, we emphasize the potential therapeutic approaches for MAFLD that target TLR4 signaling pathways, including the use of plant extracts, traditional Chinese medicines, probiotics, pharmaceuticals such as peroxisome proliferator-activated receptor antagonists and farnesol X agonists, and lifestyle modifications such as dietary changes and exercise also considered. Furthermore, TLR4 signaling pathways have also been linked to the lean MAFLD.

KEY MESSAGES

TLR4 plays a crucial role in MAFLD by triggering IR, buildup of lipids, imbalance in gut microbiota, oxidative stress, and initiation of immune responses. The mitigation of MAFLD can be accomplished by suppressing the TLR4 signaling pathway. In the future, it could potentially emerge as a therapeutic target for the condition.

Genetic and epigenetic determinants of non-alcoholic fatty liver disease (NAFLD) in lean individuals: a systematic review

Background

Non-alcoholic fatty liver disease (NAFLD) is common in obese individuals, but its occurrence in lean individuals and the underlying mechanisms are not well understood. This study aimed to systematically review the literature on the genetic and epigenetic factors influencing NAFLD in lean individuals.

Methods

A comprehensive search was conducted on April 2nd, 2023, in seven databases using specific criteria. Only peer-reviewed studies in English, focusing on genetic or epigenetic effects on NAFLD in lean individuals, were included for qualitative synthesis. The Newcastle Ottawa Scale (NOS) was used for quality assessment. This study is registered with PROSPERO (CRD42023413809).

Results

Following PRISMA guidelines, 18 studies were included in this review. The studies were conducted globally, with varying sample sizes and study designs. The NOS quality assessment revealed a moderate overall quality with variations in risk of bias and limitations in comparability and ascertainments of exposure among contributing studies. Genetic determinants related to lipid metabolism, inflammation, and oxidative stress pathways were identified, including PNPLA3 and TM6SF2 gene variants associated with increased NAFLD risk in lean individuals. Epigenetic modifications, particularly depletion of histone variants, were also implicated. However, some studies found no significant associations between genetic or clinical characteristics and lean NAFLD. Less frequent genetic risk factors, such as CETP and APOC3 gene variants, were reported.

Conclusions

This systematic review underscores the importance of investigating genetic and epigenetic factors in lean NAFLD. The findings highlight the role of PNPLA3 and TM6SF2 gene variants and suggest potential epigenetic contributions. Further research is needed to fully understand the genetic and epigenetic mechanisms underlying NAFLD in lean individuals.

Familial clustering of nonalcoholic fatty liver disease in first-degree relatives of adults with lean nonalcoholic fatty liver disease

BACKGROUND AND AIMS

The heritability of nonalcoholic fatty liver disease (NAFLD) in lean individuals is undetermined. This familial aggregation study aimed to evaluate familial linkage for NAFLD and the risk of NAFLD among first-degree relatives of probands with lean NAFLD.

METHODS

This study prospectively recruited cohorts of probands with lean NAFLD, probands with obese NAFLD, and lean probands with non-NAFLD and their respective first-degree relatives. A total of 257 participants were evaluated for liver steatosis, defined by the controlled attenuation parameter ≥288 dB/m2 , metabolic characteristics, and the PNPLA3, TM6SF2, and MBOAT7 polymorphisms.

RESULTS

The prevalence of NAFLD in first-degree relatives of lean NAFLD probands (39.9%) was similar to that in the obese NAFLD group (36.9%) and was significantly higher than in lean persons without NAFLD (19.1%). First-degree relatives of probands with NAFLD who were male, and had central obesity, hypertriglyceridaemia, insulin resistance, and the PNPLA3 rs738409C>G allele had a significantly higher prevalence of NAFLD. After multivariable adjustment for gender, metabolic characteristics, and the PNPLA3 rs738409C>G allele, first-degree relatives of probands with lean NAFLD (odds ratio [OR], 5.13; 95% CI, 1.77-14.86) and obese NAFLD (OR, 3.20; 95% CI, 1.14-8.99) exhibited an increased risk of NAFLD compared with those of lean controls without NAFLD.

CONCLUSIONS

Our well-phenotype cohorts revealed familial clustering of NAFLD and higher risks of NAFLD in first-degree relatives of probands with lean or obese NAFLD. The findings encourage clinicians caring for NAFLD patients to be more vigilant for NAFLD in their family members.

Markers of insulin resistance associated with non-alcoholic fatty liver disease in non-diabetic population

Insulin resistance (IR) plays an important role in the development of non-alcoholic fatty liver disease (NAFLD). IR markers are divided into two types: (1) insulin-based IR marker, homeostatic model assessment of IR (HOMA-IR); and (2) non-insulin-based IR markers, such as triglyceride-glucose (TyG) index, TyG index with body mass index (TyG-BMI), triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-c), and metabolic score for IR (METS-IR). The non-insulin-based IR markers are often associated with lipids. The aim of this study was to analyse the association between IR markers and NAFLD in non-diabetic population. Baseline data of NAFLD and non-NAFLD groups were compared. Logistic regression was used to evaluate the relationship between five IR markers and NAFLD risk. The odds ratios (ORs) and 95% confidence intervals (CIs) of IR markers were calculated. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were used to evaluate the ability of different IR markers to detect NAFLD. Subgroup analyses were performed in obese and non-obese subgroups. This study found a positive correlation between NAFLD risk and elevation in five IR markers (HOMA-IR, TyG, TyG-BMI, TG/HDL-c, and METS-IR). In non-obese subjects, the AUC of TyG-BMI was larger than that of the other four IR markers to detect NAFLD. The AUC of HOMA-IR was larger than that of the other four IR markers to detect NAFLD in obese subjects. In non-diabetic population, the five IR markers are associated with the risk of NAFLD, including non-obese and obese NAFLD. TyG-BMI and HOMA-IR can be used to detect non-obese and obese NAFLD, respectively, with better detection ability compared with the other IR markers.

Clinical characterization and proteomic profiling of lean nonalcoholic fatty liver disease

INTRODUCTION

Obesity has been historically associated with nonalcoholic fatty liver disease (NAFLD), but it can also occur in lean individuals. However, limited data is available on this special group. To investigate the clinical and proteomic characteristics of lean subjects with NAFLD, and to identify potential clinical variables and plasma proteins for diagnosing NAFLD in lean individuals, we collected clinical data from a large cohort of 2,236 subjects.

METHODS

Diagnosis of NAFLD relied on detecting pronounced hepatic steatosis through abdominal ultrasonography. Participants were categorized into four groups based on body mass index: overweight NAFLD, overweight control, lean NAFLD, and lean control. Plasma proteomic profiling was performed on samples from 20 subjects in each group. The lean NAFLD group was compared to both lean healthy and obese NAFLD groups across all data.

RESULTS AND DISCUSSION

The results indicated that the lean NAFLD group exhibited intermediate metabolic profiles, falling between those of the lean healthy and overweight NAFLD groups. Proteomic profiling of plasma in lean subjects with or without NAFLD revealed 45 statistically significant changes in proteins, of which 37 showed high diagnostic value (AUC > 0.7) for lean NAFLD. These potential biomarkers primarily involved lipid metabolism, the immune and complement systems, and platelet degranulation. Furthermore, AFM, GSN, CFH, HGFAC, MMP2, and MMP9 have been previously associated with NAFLD or NAFLD-related factors such as liver damage, insulin resistance, metabolic syndromes, and extracellular homeostasis. Overall, lean individuals with NAFLD exhibit distinct clinical profiles compared to overweight individuals with NAFLD. Despite having worse metabolic profiles than their healthy counterparts, lean NAFLD patients generally experience milder systemic metabolic disturbances compared to obese NAFLD patients. Additionally, the plasma proteomic profile is significantly altered in lean NAFLD, highlighting the potential of differentially expressed proteins as valuable biomarkers or therapeutic targets for diagnosing and treating NAFLD in this population.

Prevalence and risk factors of nonalcoholic fatty liver disease, high-risk nonalcoholic steatohepatitis, and fibrosis among lean United States adults: NHANES 2017-2020

Background

Nonalcoholic fatty liver disease (NAFLD) is a growing public health concern worldwide. Early detection and management of modifiable risk factors are critical to mitigating its impact. This study aimed to investigate the prevalence and risk factors of NAFLD, nonalcoholic steatohepatitis (NASH), and fibrosis among lean adults in the United States (US), using the latest National Health and Nutrition Examination Survey (NHANES) dataset from 2017-2020.

Methods

Using controlled attenuation parameter scores of ≥285 dB/m, we assessed the age-adjusted prevalence of lean NAFLD. To determine the age-adjusted prevalence of high-risk NASH and significant fibrosis, we used the FibroScan-aspartate aminotransferase (FAST) score (cutoffs 0.35 and 0.67) and vibration-controlled transient elastography (liver stiffness measurement ≥8 kPa). Multivariate logistic regression was used to identify potential risk factors.

Results

We found the age-adjusted prevalence of lean NAFLD to be 6.30%. Among lean US adults, the age-adjusted prevalence of high-risk NASH and significant fibrosis was 1.29% and 4.35%, respectively. Older age and metabolic comorbidities, such as hypertension, diabetes, and dyslipidemia were associated with NAFLD and its complications.

Conclusion

These findings suggest that the prevalence of NAFLD is of concern among lean individuals, particularly those aged 40 and older with metabolic comorbidities, while a targeted approach to screening and risk stratification for hepatic fibrosis upon lean NAFLD diagnosis is warranted.