Lean NASH: distinctiveness and clinical implication

Decreased intestinal abundance of Akkermansia muciniphila is associated with metabolic disorders among people living with HIV

BACKGROUND

Previous studies have shown changes in gut microbiota after human immunodeficiency virus (HIV) infection, but there is limited research linking the gut microbiota of people living with HIV (PLWHIV) to metabolic diseases.

METHODS

A total of 103 PLWHIV were followed for 48 weeks of anti-retroviral therapy (ART), with demographic and clinical data collected. Gut microbiome analysis was conducted using metagenomic sequencing of fecal samples from 12 individuals. Nonalcoholic fatty liver disease (NAFLD) was diagnosed based on controlled attenuation parameter (CAP) values of 238 dB/m from liver fibro-scans. Participants were divided based on the presence of metabolic disorders, including NAFLD, overweight, and hyperlipidemia. Akkermansia abundance in stool samples was measured using RT-qPCR, and Pearson correlation and logistic regression were applied for analysis.

RESULTS

Metagenomic sequencing revealed a significant decline in gut Akkermansia abundance in PLWHIV with NAFLD. STAMP analysis of public datasets confirmed this decline after HIV infection, while KEGG pathway analysis identified enrichment of metabolism-related genes. A prospective cohort study with 103 PLWHIV followed for 48 weeks validated these findings. Akkermansia abundance was significantly lower in participants with NAFLD, overweight, and hyperlipidemia at baseline, and it emerged as an independent predictor of NAFLD and overweight. Negative correlations were observed between Akkermansia abundance and both CAP values and body mass index (BMI) at baseline and at week 48. At the 48-week follow-up, Akkermansia remained a predictive marker for NAFLD.

CONCLUSIONS

Akkermansia abundance was reduced in PLWHIV with metabolic disorders and served as a predictive biomarker for NAFLD progression over 48 weeks of ART.

Non-invasive Scores and Serum Biomarkers for Fatty Liver in the Era of Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD): A Comprehensive Review From NAFLD to MAFLD and MASLD

PURPOSE OF REVIEW

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide, making it the leading cause of liver related morbidity and mortality. Currently, liver biopsy is the gold standard for assessing individuals with steatohepatitis and fibrosis. However, its invasiveness, sampling variability, and impracticality for large-scale screening has driven the search for non-invasive methods for early diagnosis and staging. In this review, we comprehensively summarise the evidence on the diagnostic performance and limitations of existing non-invasive serum biomarkers and scores in the diagnosis and evaluation of steatosis, steatohepatitis, and fibrosis.

RECENT FINDINGS

Several non-invasive serum biomarkers and scores have been developed over the last decade, although none has successfully been able to replace liver biopsy. The introduction of new NAFLD terminology, namely metabolic dysfunction-associated fatty liver disease (MAFLD) and more recently metabolic dysfunction-associated steatotic liver disease (MASLD), has initiated a debate on the interchangeability of these terminologies. Indeed, there is a need for more research on the variability of the performance of non-invasive serum biomarkers and scores across the diagnostic entities of NAFLD, MAFLD and MASLD. There remains a significant need for finding valid and reliable non-invasive methods for early diagnosis and assessment of steatohepatitis and fibrosis to facilitate prompt risk stratification and management to prevent disease progression and complications. Further exploration of the landscape of MASLD under the newly defined disease subtypes is warranted, with the need for more robust evidence to support the use of commonly used serum scores against the new MASLD criteria and validation of previously developed scores.

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.

Impact of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) on the expression and function of hepatobiliary transporters: A comprehensive mechanistic review

The liver plays a central role in the biotransformation and disposition of endogenous molecules and xenobiotics. In addition to drug-metabolizing enzymes, transporter proteins are key determinants of drug hepatic clearance. Hepatic transporters are transmembrane proteins that facilitate the movement of chemicals between sinusoidal blood and hepatocytes. Other drug transporters translocate molecules from hepatocytes into bile canaliculi for biliary excretion. The formers are known as basolateral, while the latter are known as canalicular transporters. Also, these transporters are classified into two super-families, the solute carrier transporter (SLC) and the adenosine triphosphate (ATP)-binding cassette (ABC) transporter. The expression and function of transporters involve complex regulatory mechanisms, which are contributing factors to interindividual variability in drug pharmacokinetics and disposition. A considerable number of liver diseases are known to alter the expression and function of drug transporters. Among them, non-alcoholic fatty liver disease (NAFLD) is a chronic condition with a rapidly increasing incidence worldwide. NAFLD, recently reclassified as metabolic dysfunction-associated steatotic liver disease (MASLD), is a disease continuum that includes steatosis with or without mild inflammation (NASH), and potentially neuroinflammatory pathology. NASH is additionally characterized by the presence of hepatocellular injury. During NAFLD and NASH, drug transporters exhibit altered expression and function, leading to altered drug pharmacokinetics and pharmacodynamics, thus increasing the risk of adverse drug reactions. The purpose of the present review is to provide comprehensive mechanistic information on the expression and function of hepatic transporters under fatty liver conditions and hence, the impact on the pharmacokinetic profiles of certain drugs from the available pre-clinical and clinical literature.

Antibody against apolipoprotein-A1, non-alcoholic fatty liver disease and cardiovascular risk: a translational study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease increasing cardiovascular disease (CVD) morbidity and mortality. Autoantibodies against apolipoprotein A-1 (AAA-1) are a possible novel CVD risk factor promoting inflammation and disrupting cellular lipid homeostasis, two prominent pathogenic features of NAFLD. We explored the role of AAA-1 in NAFLD and their association with CVD risk.

METHODS

HepaRG cells and liver sections from ApoE-/- mice exposed to AAA-1 were used for lipid quantification and conditional protein expression. Randomly selected sera from 312 subjects of the Prevention of Renal and Vascular End-stage Disease (PREVEND) general population cohort were used to measure AAA-1. A Fatty Liver Index (FLI) ≥ 60 and a 10-year Framingham Risk Score (FRS) ≥ 20% were used as proxy of NAFLD and high CVD risk, respectively.

RESULTS

In-vitro and mouse models showed that AAA-1 increased triglyceride synthesis leading to steatosis, and promoted inflammation and hepatocyte injury. In the 112 PREVEND participants with FLI ≥ 60, AAA-1 were associated with higher FRS, alkaline phosphatase levels, lower HDL cholesterol and tended to display higher FLI values. Univariate linear and logistic regression analyses (LRA) confirmed significant associations between AAA-1, FLI and FRS ≥ 20%, while in adjusted LRA, FLI was the sole independent predictor of FRS ≥ 20% (OR: 1.05, 95%CI 1.01-1.09, P = 0.003). AAA-1 was not an independent FLI predictor.

CONCLUSIONS

AAA-1 induce a NAFLD-compatible phenotype in vitro and in mice. Intricate associations exist between AAA-1, CVD risk and FLI in the general population. Further work is required to refine the role of AAA-1 in NAFLD and to determine if the AAA-1 association with CVD is affected by hepatic steatosis.

Metabolic characteristics of non-obese and obese metabolic dysfunction-associated fatty liver disease in type 2 diabetes mellitus and its association with diabetic peripheral neuropathy and diabetic retinopathy

Aim

To assess the metabolic characteristics of non-obese metabolic dysfunction-associated fatty liver disease (MAFLD) compared with obese MAFLD and the relationship of MAFLD with diabetic peripheral neuropathy and diabetic retinopathy in patients with Type 2 diabetes mellitus (T2DM).

Methods

Data were obtained from 536 T2DM patients (355 women, 181 men; age 58.2 ± 12.0 years). We explored the difference in clinical characteristics between obese MAFLD (body mass index ≥25 kg/m2) and non-obese MAFLD (body mass index <25 kg/m2) in T2DM patients. One-way analysis of variance (ANOVA) was used to compare the means of continuous variables, and the Chi-squared test was used to compare the differences in frequencies of categorical variables. Logistic regression models were adopted to calculate odds ratios.

Results

The prevalence of MAFLD in hospitalized Chinese T2DM patients was calculated to be 42.7%. Both obese and non-obese MAFLD patients had higher levels of body mass index (BMI), waist circumfere nce, triglyceride, alanine aminotransferase, aspar tate aminotransferase, γ-glutamyltransferase, you nger age, higher prevalence of hyperlipidemia and shorter duration of T2DM and lower incidence of diabetic retinopathy, compared with participants with out MAFLD in the same weight group. Uric acid levels were positively correlated with the risk of MAFLD only in non-obese subjects but not in obese subjects. In non-obese patients with T2DM, a negative correlation was found between the prevalence of MAFLD and diabetic retinopathy.

Conclusion

Even in non-obese patients with T2DM, BMI was found to be an independent risk factor for MAFLD. These findings support a more structured, risk-factor-based approach to MAFLD management, particularly in patients with T2DM. Non-obese MAFLD has unique results in metabolic characteristics and the correlation with diabetic retinopathy and diabetic peripheral neuropathy, which should be further explored.

Hyperuricemia as an independent risk factor for metabolic dysfunction-associated fatty liver disease in nonobese patients without type 2 diabetes mellitus

According to the latest consensus statement, fatty liver complicated by specific metabolic abnormalities can be diagnosed as metabolic dysfunction-associated fatty liver disease (MAFLD) in nonobese patients without type 2 diabetes mellitus (T2DM). However, hyperuricemia (HUA), a manifestation of metabolic disorders, is excluded from diagnostic criteria. This study explored the association between HUA and MAFLD in nonobese patients without T2DM. A total of 28,187 participants were recruited from the Examination Center of the China-Japan Friendship Hospital from 2018 to 2022 and divided into four subgroups: nonobese patients without T2DM, obese patients without T2DM, nonobese patients with T2DM, and obese patients with T2DM. MAFLD was diagnosed by ultrasound combined with laboratory examinations. The association of HUA with MAFLD subgroups was performed by logistical regression analysis. The predictive ability of UA for MAFLD subgroups was assessed by receiver operating characteristics (ROC). HUA was positively associated with MAFLD in nonobese patients without T2DM in both males and females, even after adjusting for sex, BMI, dyslipidemia, and abnormal liver function. The association increased gradually with aging, especially in those over 40 yr old. HUA was an independent risk factor for MAFLD in nonobese patients without T2DM. We suggest that UA abnormalities might be considered in the diagnosis of MAFLD in nonobese patients without T2DM.NEW & NOTEWORTHY HUA is an independent risk factor for MAFLD in nonobese patients without T2DM. The association of HUA with MAFLD in nonobese patients without T2DM increased gradually with aging, especially in those over 40 yr old. In nonobese patients without T2DM, univariate analysis showed that females with HUA had a higher risk of MAFLD than males. However, the difference was narrowed after adjustment for confounders.

Lipid droplet biogenesis and functions in health and disease

Ubiquitous yet unique, lipid droplets are intracellular organelles that are increasingly being recognized for their versatility beyond energy storage. Advances uncovering the intricacies of their biogenesis and the diversity of their physiological and pathological roles have yielded new insights into lipid droplet biology. Despite these insights, the mechanisms governing the biogenesis and functions of lipid droplets remain incompletely understood. Moreover, the causal relationship between the biogenesis and function of lipid droplets and human diseases is poorly resolved. Here, we provide an update on the current understanding of the biogenesis and functions of lipid droplets in health and disease, highlighting a key role for lipid droplet biogenesis in alleviating cellular stresses. We also discuss therapeutic strategies of targeting lipid droplet biogenesis, growth or degradation that could be applied in the future to common diseases, such as cancer, hepatic steatosis and viral infection.

Lean or diabetic subtypes predict increased all-cause and disease-specific mortality in metabolic-associated fatty liver disease

BACKGROUND

Metabolic-associated fatty liver disease (MAFLD) encompasses diverse disease groups with potentially heterogeneous clinical outcomes. We investigated the risk of all-cause and disease-specific mortality in MAFLD subgroups.

METHODS

Using the Korean National Health Insurance Service database, participants were divided into four subgroups: no MAFLD, MAFLD-diabetes, MAFLD-overweight/obese, and MAFLD-lean. Hazard ratios (HRs) and 95% confidence interval (CI) values for all-cause and disease-specific mortality according to MAFLD subgroups were analyzed using Cox proportional hazards models.

RESULTS

Among 9,935,314 participants, those with MAFLD-diabetes showed the highest risk of all-cause and disease-specific mortality. The HRs (95% CI) for all-cause mortality were 1.61 (1.59-1.63), 1.36 (1.34-1.38), and 1.19 (1.18-1.20) in the MAFLD-diabetes, MAFLD-lean, and MAFLD-overweight/obese groups, respectively. The magnitude of cardiovascular disease and cancer-related risk showed the same pattern. The risk of liver-related mortality in the MAFLD-lean group (HR: 2.84, 95% CI: 2.72-2.97) was comparable with that in the MAFLD-diabetes group (HR: 2.85, 95% CI: 2.75-2.95). When stratified by body mass index, liver-related mortality was the highest in MAFLD-lean individuals in the underweight group (HR, 5.03, 95% CI: 4.23-5.97).

CONCLUSIONS

The MAFLD-lean and MAFLD-diabetes groups had a higher risk of all-cause and disease-specific mortality than did the MAFLD-overweight/obese group. Classifying MAFLD subgroups based on metabolic phenotypes might help risk stratification of patients with MAFLD.

Fatty liver disease in children (MAFLD/PeFLD Type 2): unique classification considerations and challenges

In children, fatty liver disease is a group of disorders that often overlaps with inherited metabolic disorders (IMDs), which requires prompt diagnosis and specific management. Metabolic dysfunction-associated fatty liver disease (MAFLD) or, formerly, non-alcoholic fatty liver disease (NAFLD) is the hepatic component of a multisystemic disease that requires a positive criteria in metabolic dysfunction for diagnosis. However, in children, the diagnosis of MAFLD is one of the exclusions of an IMD [paediatric fatty liver disease (PeFLD) type 1] including the possibility that an IMD can be identified in the future following investigations that may be negative at the time. Therefore, while children with fatty liver with metabolic dysfunction could be classified as MAFLD (PeFLD type 2) and managed that way, those who do not fulfil the criteria for metabolic dysfunction should be considered separately bearing in mind the possibility of identifying a yet undiagnosed IMD (PeFLD type 3). This concept is ever more important in a world where MAFLD is the most common cause of liver disease in children and adolescents in whom about 7% are affected. The disease is only partially understood, and awareness is still lacking outside hepatology and gastroenterology. Despite its increasing pervasiveness, the management is far from a one-size-fits-all. Increasing complexities around the genetic, epigenetic, non-invasive modalities of assessment, psychosocial impacts, therapeutics, and natural history of the disease have meant that an individualised approach is required. This is where the challenge lies so that children with fatty liver are considered on their own merits. The purpose of this review is to give a clinical perspective of fatty liver disease in children with relevance to metabolic dysfunction.

Lower Circulating Leptin Levels Are Related to Non-Alcoholic Fatty Liver Disease in Children With Obesity

Background

While for individuals with obesity an association between hyperleptinemia and an increased risk of non-alcoholic fatty liver disease (NAFLD) is assumed, a leptin deficiency is also related to the development of NAFLD early in life in ob/ob mice, in patients with leptin deficiency due to biallelic likely pathogenic variants in the leptin gene, and in patients with lipodystrophy.

Objectives

To investigate the association of circulating leptin levels in pre-pubertal children with obesity and steatosis hepatis.

Methods

The cross-sectional study consisted data of n=97 (nmale=76) pre-pubertal children (11.8 ± 1.5 years) with obesity (BMIz: 2.4 ± 0.4). Fasting concentrations of cardiometabolic parameters were measured: insulin, c-peptide, glucose, triglyceride, cholesterol, HDL, LDL, AST, ALT, GGT, leptin. Steatosis hepatis was diagnosed by an ultrasound examination (mild, moderate or severe). Patients were categorized into two groups: low z-score of circulating leptin levels (≤25th percentile) vs. normal z-score of circulating leptin levels.

Results

One-third of the children with obesity were diagnosed with steatosis hepatis (I°: 63.6%, II°/III°: 36.4%). Children with steatosis hepatis had significantly lower z-scores of circulating leptin levels compared to children with an unremarkable liver ultrasonography (-2.1 ± 0.8 vs. -0.7 ± 0.6). Z-scores of circulating leptin levels correlate negatively with degree of steatosis hepatis. Children with low z-scores of circulating leptin levels had significantly higher triglyceride, fasting insulin and c-peptide levels compared to children with normal z-scores of circulating leptin levels.

Conclusion

Prepubertal children with NAFLD and obesity and partial leptin deficiency might be defined as a clinical subgroup.

Steroid-mediated liver steatosis is CD1d-dependent, while steroid-induced liver necrosis, inflammation, and metabolic changes are CD1d-independent

Introduction

Glucocorticoids contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Natural killer T cells play a role in the pathogenesis of NAFLD and response to steroids. The present study aimed to determine the role of CD1d in steroid-mediated metabolic derangement and the steroid-protective effect of glycosphingolipids.

Methods

Ten groups of mice were studied. Steroids were orally administered to C57BL/6 mice to assess the therapeutic effect of β-glucosylceramide (GC) on the development of steroid-mediated liver damage and metabolic derangements. The role of CD1d in the pathogenesis of steroid-induced liver damage and in mediating the hepatoprotective effect of GC was studied in CD1d^−/− mice.

Results

A model of oral administration of steroids was established, resulting in insulin resistance, hyperinsulinemia, hypertriglyceridemia, liver steatosis, and hepatocellular injury. Steroid administration to CD1d^−/− mice was associated with hyperglycemia and hypertriglyceridemia. However, CD1d^−/− mice did not manifest marked steroid-induced steatosis. GC treatment alleviated steroid-associated metabolic derangements and liver injury independent of CD1d expression.

Conclusion

A steroid-mediated model of NAFLD and metabolic derangements was established in which steroid-mediated steatosis was CD1d-dependent while steroid-induced liver necrosis, inflammation, and metabolic changes were CD1d-independent, which may support a dichotomy between steatosis and steatohepatitis in NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02242-9.

Cardiovascular Risk Is Elevated in Lean Subjects with Nonalcoholic Fatty Liver Disease

BACKGROUND/AIMS

: Nonalcoholic fatty liver disease (NAFLD) and obesity are independently associated with an increased risk for atherosclerotic cardiovascular disease (ASCVD), the leading cause of mortality in patients with NAFLD. Many NAFLD patients are lean, but their ASCVD risk compared to obese subjects with NAFLD is unclear.

METHODS

Data from the 2008 to 2011 Korea National Health and Nutrition Examination Surveys database were analyzed (n=4,786). NAFLD was defined as a comprehensive NAFLD score ≥40 or a liver fat score ≥-0.640. ASCVD risk was evaluated using the American College of Cardiology/ American Heart Association guidelines.

RESULTS

The frequency of subjects without NAFLD, with obese NAFLD, and with lean NAFLD was 62.4% (n=2,987), 26.6% (n=1,274), and 11.0% (n=525), respectively. Subjects with lean NAFLD had a significantly higher ASCVD score and prevalence of a high ASCVD risk (mean 15.6±14.0, 51.6%) than those with obese NAFLD and without NAFLD (mean 11.2±11.4, 39.8%; mean 7.9±10.9, 25.5%; all p<0.001). Subjects with lean NAFLD and significant liver fibrosis showed a significantly higher odds ratio for a high risk for ASCVD than those with obese NAFLD with or without significant liver fibrosis (odds ratio, 2.60 vs 1.93; p=0.023).

CONCLUSIONS

Subjects with lean NAFLD had a significantly higher ASCVD score and prevalence of high risk for ASCVD than those with obese NAFLD. Similarly, lean subjects with significant liver fibrosis had a higher probability of ASCVD than obese subjects in the subpopulation with NAFLD.

Links between metabolic syndrome and metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition characterized by hepatic fat accumulation combined with underlying metabolic dysregulation. Having evolved from the previous term of nonalcoholic fatty liver disease (NAFLD), the term MAFLD more closely implicates the presence of overweight/obesity, type 2 diabetes, or metabolic dysregulation as essential pathogenic factors, leading to better identification of individuals with this metabolic liver disease. Low-grade inflammation, increased oxidative stress, mitochondrial dysfunction, and intestinal dysbiosis are also involved in its pathogenesis. MAFLD is not only associated with liver-related complications, but also with adverse cardiometabolic outcomes. Further studies are needed to assess whether the newly proposed definition of MAFLD is more accurate than the NAFLD in predicting the adverse liver-related and extrahepatic outcomes.

Pathology of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of different conditions which are characterized by hepatic steatosis in the absence of secondary causes. It is currently the most common chronic liver disease worldwide, and its estimated prevalence is about 1.5-6.5%. The only histological finding of steatosis (“simple” steatosis) represents the uncomplicated form of NAFLD, while non-alcoholic steatohepatitis (NASH) is its inflammatory subtype associated with disease progression to cirrhosis and hepatocellular carcinoma (HCC), and represents the major indication for liver transplantation. NASH is still a diagnostic and therapeutic challenge for clinicians and liver biopsy is currently the only accepted method to reliably distinguish NASH from “simple” steatosis. From the histological perspectives, NAFLD and NASH continue to be an area of active interest for pathologists, with a specific focus on better methods of evaluation, morphologic clues to pathogenesis, and predictors of fibrosis progression. This review focuses on histopathology of NAFLD in adults, with the aim to provide a practical diagnostic approach useful in the clinical routine.

Exome-wide scan identifies significant association of rs4788084 in IL27 promoter with increase in hepatic fat content among Indians

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a global epidemic that often progresses to liver cirrhosis and hepatocellular carcinoma. In contrast to most world populations where NAFLD is mostly prevalent among obese, NAFLD among Indians and generally among South and South-East Asians is unique and highly prevalent among individuals who are lean. Genetics of NAFLD in Indian populations is understudied. In this study, we have used an exome-wide approach to identify genetic determinants of hepatic fat content (HFC) in India.

METHODS

HFC was measured in 244 participants using Proton magnetic resonance spectroscopy (H1-MRS). Quantitative trait loci (QTL) mapping was done exome-wide, to identify SNPs associated with HFC. The effects of the interaction between adiposity and QTLs on HFC were studied using a regression model. Association of the significant loci with disease severity was studied in 146 NAFLD patients among 244 participants, who underwent liver biopsy.

RESULTS

Our study identified 4 significantly associated SNPs (rs738409 and rs2281135 (PNPLA3), rs3761472 (SAMM50), rs17513722 (FAM161A) and rs4788084), with HFC after adjusting for the effects of covariates (p-value < 0.0005). rs738409, rs2281135 (PNPLA3), and rs3761472 (SAMM50) were associated with hepatocyte ballooning, lobular and portal inflammation and non-alcoholic steatohepatitis (NASH) (p-value < 0.05). rs4788048 is an eQTL for IL27 and SULT1A2 genes, both of which are highly expressed in healthy livers and are likely to be involved in NAFLD pathogenesis.

CONCLUSIONS

Our study identified the novel association of rs4788084 with HFC, which regulates the expression of IL-27, an immune regulatory gene. We further showed that adiposity affected the HFC, irrespective of the genetic predisposition.

Clinical profile of non-alcoholic fatty liver disease in nonobese patients

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) is associated with metabolic syndrome. Worryingly, it has been increasingly reported among nonobese patients. This study aims to analyse patient characteristics of biopsy-proven NAFLD in an Asian cohort and explore differences stratified by body mass index (BMI).

METHODS

Clinical, laboratory, and histological data were collected from 263 adults with biopsy-proven NAFLD. Patients with and without obesity (BMI cut-off 25) were compared. The ability to predict advanced liver fibrosis with three non-invasive scores, the NAFLD Fibrosis score (NFS), Fibrosis-4 (FIB4), and the aspartate aminotransferase to platelet ratio index (APRI), was compared.

RESULTS

Obese subjects had a lower mean age (49.5 ± 12.5 vs 54.0 ± 12.9 years, P = 0.017), a higher prevalence of diabetes (52.4% vs 36.8%, P = 0.037), and a higher waist circumference (113.9 ± 16.0 cm vs 87.0 ± 18.4 cm, P = 0.022). The prevalence of dyslipidaemia (68.0% vs 61.4%, P = 0.353) and hypertension (61.7% vs 49.1%, P = 0.190) was comparable between the two groups. The distribution of non-alcoholic steatohepatitis (NASH) (63.1% versus 61.4%, P = 0.710) and advanced fibrosis (31.6% versus 26.3%, P = 0.447) were also similar in both groups. All three non-invasive scores (NFS, FIB4, and APRI) performed poorly in predicting advanced fibrosis in nonobese patients with NAFLD. The FIB4 was the most accurate non-invasive score in predicting advanced fibrosis in the obese group.

CONCLUSIONS

Obese and nonobese patients are equally at risk of NASH and advanced fibrosis. While the FIB4 is the most accurate non-invasive score in predicting advanced fibrosis among obese individuals, further research is warranted to develop a nonobese specific score to correctly identify nonobese NAFLD patients with advanced fibrosis.

What Are the Current Pharmacological Therapies for Nonalcoholic Fatty Liver Disease?

Of the currently available drugs tested to treat nonalcoholic fatty liver disease (NAFLD), the most efficacious drugs are pioglitazone (an insulin sensitizer) and vitamin E (an antioxidant). By targeting insulin resistance, the key pathogenic mechanism underlying metabolic syndrome and NAFLD, pioglitazone maybe the preferred drug to treat NAFLD. As we await the results of research trials into multiple new drugs to treat NAFLD, when should we use the currently available patients to treat NAFLD at the present time? To date, no drug has been approved by regulatory agency specifically to treat NAFLD. However, many drugs have been approved to treat other components of metabolic syndrome such as diabetes mellitus and dyslipidemia. Are we underutilizing the currently available drugs to treat NAFLD? Herein, we review the benefits and concerns of the use of these currently available drugs to treat NAFLD and suggest clinical scenarios, wherein the clinician should consider using these drugs.

JAK1 Inhibition Blocks Lethal Immune Hypersensitivity in a Mouse Model of Down Syndrome

Individuals with Down syndrome (DS; trisomy 21) display hyperactivation of interferon (IFN) signaling and chronic inflammation, which could potentially be explained by the extra copy of four IFN receptor (IFNR) genes encoded on chromosome 21. However, the clinical effects of IFN hyperactivity in DS remain undefined. Here, we report that a commonly used mouse model of DS overexpresses IFNR genes and shows hypersensitivity to IFN ligands in diverse immune cell types. When treated repeatedly with a TLR3 agonist to induce chronic inflammation, these animals overexpress key IFN-stimulated genes, induce cytokine production, exhibit liver pathology, and undergo rapid weight loss. Importantly, the lethal immune hypersensitivity and cytokine production and the ensuing pathology are ameliorated by JAK1 inhibition. These results indicate that individuals with DS may experience harmful hyperinflammation upon IFN-inducing immune stimuli, as observed during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, pointing to JAK1 inhibition as a strategy to restore immune homeostasis in DS.

Non-Alcoholic Steatohepatitis: A Review of Its Mechanism, Models and Medical Treatments

Non-alcoholic steatohepatitis (NASH) develops from non-alcoholic fatty liver disease (NAFLD). Currently, around 25% of the population is estimated to have NAFLD, and 25% of NAFLD patients are estimated to have NASH. NASH is typically characterized by liver steatosis inflammation, and fibrosis driven by metabolic disruptions such as obesity, diabetes, and dyslipidemia. NASH patients with significant fibrosis have increased risk of developing cirrhosis and liver failure. Currently, NASH is the second leading cause for liver transplant in the United States. More importantly, the risk of developing hepatocellular carcinoma from NASH has also been highlighted in recent studies. Patients may have NAFLD for years before progressing into NASH. Although the pathogenesis of NASH is not completely understood, the current “multiple-hits” hypothesis suggests that in addition to fat accumulation, elevated oxidative and ER stress may also drive liver inflammation and fibrosis. The development of clinically relevant animal models and pharmacological treatments for NASH have been hampered by the limited understanding of the disease mechanism and a lack of sensitive, non-invasive diagnostic tools. Currently, most pre-clinical animal models are divided into three main groups which includes: genetic models, diet-induced, and toxin + diet-induced animal models. Although dietary models mimic the natural course of NASH in humans, the models often only induce mild liver injury. Many genetic and toxin + diet-induced models rapidly induce the development of metabolic disruption and serious liver injury, but not without their own shortcomings. This review provides an overview of the “multiple-hits” hypothesis and an evaluation of the currently existing animal models of NASH. This review also provides an update on the available interventions for managing NASH as well as pharmacological agents that are currently undergoing clinical trials for the treatment of NASH.

MAFLD: A Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease

Fatty liver associated with metabolic dysfunction is common, affects a quarter of the population, and has no approved drug therapy. Although pharmacotherapies are in development, response rates appear modest. The heterogeneous pathogenesis of metabolic fatty liver diseases and inaccuracies in terminology and definitions necessitate a reappraisal of nomenclature to inform clinical trial design and drug development. A group of experts sought to integrate current understanding of patient heterogeneity captured under the acronym nonalcoholic fatty liver disease (NAFLD) and provide suggestions on terminology that more accurately reflects pathogenesis and can help in patient stratification for management. Experts reached consensus that NAFLD does not reflect current knowledge, and metabolic (dysfunction) associated fatty liver disease "MAFLD" was suggested as a more appropriate overarching term. This opens the door for efforts from the research community to update the nomenclature and subphenotype the disease to accelerate the translational path to new treatments.

Epidemiology of non-alcoholic and alcoholic fatty liver diseases

Liver diseases are fast emerging as global health priorities. Fatty liver is described in the setting of non-alcoholic fatty liver disease (NAFLD) as well as alcoholic liver disease (ALD), the pathogenesis of excess fat being different in the two conditions while both are important components of the changing face of burden of liver diseases worldwide. They are intimately associated with a globalized economy and an increasingly homogenous socio- cultural order with a westernized lifestyle. The accompanying adoption of a progressively sedentary life, consumption of diet dense in calories facilitate development of NAFLD while a spiraling upward trend in alcohol use along with earlier age of drinking as well as increased amount of per capita alcohol consumption increases the prevalence of ALD globally. Adverse health outcomes in NAFLD as well as ALD are caused not only by progressive liver fibrosis that is the most significant factor for liver related and all-cause mortality in both but also by non-liver (cardiovascular, cancer, accidents, neurological) clinical outcomes that calls for a multidisciplinary and social approach to these conditions. We present here an outline of facets of epidemiology of both NAFLD as well as ALD along with its' public health implications. A broad-based integrated approach that incorporates social, behavioral as well as biological targets need to be undertaken at a health system level in a planned manner for these evolving liver health priorities that disproportionately challenges the low- and middle-income countries of Asia, South America and Africa.

Lean NAFLD: A Distinct Entity Shaped by Differential Metabolic Adaptation

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) affects a quarter of the adult population. A significant subset of patients are lean, but their underlying pathophysiology is not well understood.

APPROACH AND RESULTS

We investigated the role of bile acids (BAs) and the gut microbiome in the pathogenesis of lean NAFLD. BA and fibroblast growth factor (FGF) 19 levels (a surrogate for intestinal farnesoid X receptor [FXR] activity), patatin-like phospholipase domain containing 3 (PNPLA3), and transmembrane 6 superfamily member 2 (TM6SF2) variants, and gut microbiota profiles in lean and nonlean NAFLD were investigated in a cohort of Caucasian patients with biopsy-proven NAFLD (n = 538), lean healthy controls (n = 30), and experimental murine models. Patients with lean NAFLD had a more favorable metabolic and histological profile compared with those with nonlean NAFLD (P < 0.05 for all). BA levels were significantly higher in NAFLD with advanced compared with earlier stages of liver fibrosis. Patients with lean NAFLD had higher serum secondary BA and FGF19 levels and reduced 7-alpha-hydroxy-4-cholesten-3-one (C4) levels (P < 0.05 for all). These differences were more profound in early compared with advanced stages of fibrosis (P < 0.05 for both). Lean patients demonstrated an altered gut microbiota profile. Similar findings were demonstrated in lean and nonlean murine models of NAFLD. Treating mice with an apical sodium-dependent BA transporter inhibitor (SC-435) resulted in marked increases in fgf15, a shift in the BA and microbiota profiles, and improved steatohepatitis in the lean model.

CONCLUSIONS

Differences in metabolic adaptation between patients with lean and nonlean NAFLD, at least in part, explain the pathophysiology and provide options for therapy.

Correlation between insulin resistance and liver histology in patients with nonalcoholic steatohepatitis with and without obesity

INTRODUCTION

Insulin resistance (IR) plays a central role in pathogenesis of nonalcoholic steatohepatitis (NASH). The aim of this study was to correlate histopathological grading and IR in overweight/obese patients with NASH as compared with lean NASH.

METHODS

Patients with NASH who underwent liver biopsy between January 2012 and December 2012 were included. Anthropometric, clinical, and biochemical features, necro-inflammatory grades, and fibrosis stage on liver biopsies were scored according to Brunt and non-alcoholic fatty liver disease (NAFLD) activity score (NAS).

RESULTS

Of 42 patients, 33 (78.6%) had body mass index (BMI) ≥ 23 kg/m² (overweight/obese) while 9 had BMI < 23 kg/m² (lean). Mean fasting blood sugar (FBS) and HbA1c levels in overweight/obese patients with NASH were higher than in lean NASH (p < 0.05). The median homeostatic model assessment-estimated insulin resistance (HOMA-IR) among NASH patients with BMI ≥ 23 kg/m² was higher than among those with BMI < 23 kg/m² (3.02 [0.34-17.22] vs. 2 [0.52-5.26]; p = 0.045). However, fasting insulin levels were comparable among lean and overweight/obese patients with NASH. Metabolic syndrome could be predicted with 75% sensitivity and 85.3% specificity at a HOMA-IR cutoff value of 3.9. No significant difference was observed with regard to HOMA-IR levels with Brunt grades, Brunt staging, Brunt grades 1 and 2, Brunt scores < 2 and > 2, and NAS scores, and NAS scores < 4 and > 4.

CONCLUSIONS

Although IR was significantly higher in overweight/obese patients with NASH as compared with that in lean patients with NASH, there was no difference in the correlation of HOMA-IR with histology between these groups.

Effect of Weight Reduction on Histological Activity and Fibrosis of Lean Nonalcoholic Steatohepatitis Patient

BACKGROUND AND OBJECTIVES

Weight reduction has evidenced benefit on attenuation of histological activity and fibrosis of nonalcoholic steatohepatitis (NASH), but there is scarcity of data for lean NASH subgroup. We have designed this study to compare the effects of weight reduction on histological activity and fibrosis of lean and non-lean NASH.

METHODS

We have included 20 lean and 20 non-lean histologically proven NASH patients. BMI < 25 kg/m2 was defined as non-lean. Informed consent was taken from each subject. All methods were carried out in accordance with the Declaration of Helsinki. Moderate exercise along with dietary restriction was advised for both groups for weight reduction. After 1 year, 16 non-lean and 15 lean had completed second liver biopsy.

RESULTS

Age, sex, alanine transaminase (ALT), aspartate aminotransferase (AST), gamma-glutamyltrasferase (GGT), Homeostasis model assessment insulin resistance (HOMA-IR), triglyceride and high density lipoprotein (HDL) was similar in both groups. Steatosis, ballooning, lobular inflammation, nonalcoholic fatty liver disease activity score (NAS) and fibrosis was similar in the two groups. In lean/non-lean group, any amount of weight reduction, ≥ 5% weight reduction and ≥ 7% weight reduction was found in respectively 8/11, 5/6 and 2/6 patients. In both lean and non-lean groups, weight reduction of any amount was associated with significant reduction of steatosis, ballooning and NAS, except lobular inflammation and fibrosis. In both groups, weight reduction of ≥ 5% was associated with significant reduction in NAS only. However, significant improvement in NAS was noted with ≥ 7% weight reduction in non-lean group only.

CONCLUSION

Smaller amount of weight reduction had the good benefit of improvement in all the segments of histological activity in both lean and non-lean NASH.

Recent research trends and updates on nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), together with metabolic syndrome and obesity, has shown a rapid increase in prevalence worldwide and is emerging as a major cause of chronic liver disease and liver transplantation. Among the various phenotypes of NAFLD, nonalcoholic steatohepatitis (NASH) is highly likely to progress to development of end-stage liver disease and cardiometabolic disease, resulting in liver-related and non-liver-related mortality. Nonetheless, there is no standardized pharmacotherapy against NASH and many drugs are under development in ongoing clinical trials. To develop a successful anti-NASH drug, it is necessary to select an appropriate target population and treatment outcomes depending on whether the mode of action is anti-metabolic, anti-inflammatory or anti-fibrotic. Recently, innovative surrogate markers have been investigated to replace hard outcomes such as liver histology and mortality and reduce the clinical trial duration. Currently, several drugs with fast track designation are being tested in phase III clinical trials, and many other drugs have moved into phase II clinical trials. Both lean NAFLD and typical obese NAFLD have been extensively studied and genetic variants such as PNPLA3 and TM6SF2 have been identified as significant risk factors for lean NAFLD. In the near future, noninvasive biomarkers and effective targeted therapies for NASH and associated fibrosis are required to develop precision medicine and tailored therapy according to various phenotypes of NAFLD.

Personalized therapy when tackling nonalcoholic fatty liver disease: a focus on sex, genes, and drugs

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease in the world. It describes a term for a group of hepatic diseases including steatosis, fibrosis, and cirrhosis that can finally lead to hepatocellular carcinoma. There are many factors influencing NAFLD initiation and progression, such as obesity, dyslipidemia, insulin resistance, genetic factors, and hormonal changes. However, there is also lean-NAFLD which is not associated with obesity. NAFLD is considered to be a sexually dimorphic disease. In most cases, men have a higher prevalence for the disease compared to premenopausal women. Areas covered: In this review, we first summarize the NAFLD disease epidemiology, pathology, and diagnosis. We describe NAFLD progression with the focus on sexual and genetic differences for disease development and pharmacological treatment. Personalized treatment for multifactorial NAFLD is discussed in consideration of different factors, including genetics, gender and sex. Expert opinion: The livers of female and male NAFLD patients have different metabolic capacities which influence the metabolism of all drugs applied to such patients. This aspect is not yet sufficiently taken into account. The liver computational models might quicken the pace toward assessing personalized disease progression and treatment options.

Lean Metabolic Syndrome: A Concept or a Reality?

AIMS AND OBJECTIVES

Metabolic syndrome (MetS) is fairly common in India. International Diabetes Federation (IDF) has defined it as the presence of central obesity with region/ethnicity-specific waist circumference as a mandatory defining criterion along with the presence of two other features from dysglycemia, systolic and/or diastolic hypertension, hypertriglyceridemia, and low high-density lipoprotein. Although obesity is not prevalent in rural parts of India, especially among the underprivileged population, other individual components of the syndrome are not infrequent among these lean/nonobese persons. In this study, we evaluated the prevalence of MetS in rural West Bengal. We also examined that if those persons above the recommended cutoff for waist are excluded, and thus only lean/nonobese persons are included, and the same definition of MetS (herein termed as lean MetS) is applied (three out of four criteria), what will be the prevalence of MetS and will it be lower in the nontribal population compared to the tribal population?

MATERIALS AND METHODS

A population-based study was done in the rural area of West Bengal comprising 205 [corrected] peoples from scheduled tribe (ST) population and 200 [corrected] people from the neighborhood community from non-ST population to compare the metabolic health with respect to anthropologic and biochemical parameters.

RESULTS

The prevalence of MetS from rural areas of West Bengal was found to be 21.48% as per IDF criterion, but applying NCEP ATP III criteria, the overall prevalence of MetS rose to 31.1%. The prevalence of normal waist/lean MetS was 12.8%, and there was no significant difference between nontribals versus tribal cohort (14.6% of the nontribes versus 11.6% of the tribal cohort, P = 0.436).

CONCLUSION

A significant number of persons with nonobese/lean MetS exist in the rural area. We suggest that if region-specific waist criteria are not satisfied, the diagnosis should still be sorted by NCEP ATP III criteria.

Clinical and Metabolic Characterization of Lean Caucasian Subjects With Non-alcoholic Fatty Liver

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is closely linked to obesity; however, 5-8% of lean subjects also have evidence of NAFLD. We aimed to investigate clinical, genetic, metabolic and lifestyle characteristics in lean Caucasian subjects with NAFLD.

METHODS

Data from 187 subjects allocated to one of the three groups according to body mass index (BMI) and hepatic steatosis on ultrasound were obtained: lean healthy (BMI≤25 kg/m², no steatosis, N=71), lean NAFLD (BMI≤25 kg/m², steatosis, N=55), obese NAFLD (BMI≥30 kg/m², steatosis; N=61). All subjects received a detailed clinical and laboratory examination including oral glucose tolerance test. The serum metabolome was assessed using the Metabolomics AbsoluteIDQ p180 kit (BIOCRATES Life Sciences). Genotyping for single-nucleotide polymorphisms (SNPs) associated with NAFLD was performed.

RESULTS

Lean NAFLD subjects had fasting insulin concentrations similar to lean healthy subjects but had markedly impaired glucose tolerance. Lean NAFLD subjects had a higher rate of the mutant PNPLA3 CG/GG variant compared to lean controls (P=0.007). Serum adiponectin concentrations were decreased in both NAFLD groups compared to controls (P<0.001 for both groups) The metabolomics study revealed a potential role for various lysophosphatidylcholines (lyso-PC C18:0, lyso-PC C17:0) and phosphatidylcholines (PCaa C36:3; false discovery rate (FDR)-corrected P-value<0.001) as well as lysine, tyrosine, and valine (FDR<0.001).

CONCLUSIONS

Lean subjects with evidence of NAFLD have clinically relevant impaired glucose tolerance, low adiponectin concentrations and a distinct metabolite profile with an increased rate of PNPLA3 risk allele carriage.

Oxidized low-density lipoprotein antibodies/high-density lipoprotein cholesterol ratio is linked to advanced non-alcoholic fatty liver disease lean patients

BACKGROUND AND AIM

A small but significant proportion of patients with normal body mass index show non-alcoholic fatty liver disease (NAFLD). Oxidized low-density lipoprotein (LDL) is a powerful immunogenic molecule, which causes oxidative stress and produces antibodies (oxLDL-ab). We aimed to analyze the role of oxLDL-ab on histological features in lean-NAFLD patients.

METHODS

Seventy-two biopsy-proven NAFLD patients were included. Lean patients showed body index mass of <30 kg/m(2) . Liver biopsies were assessed by one pathologist blinded to clinical data. Histological features were non-alcoholic steatohepatitis (NASH), steatosis, hepatocellular ballooning, and liver fibrosis. Metabolic and hepatic profiles were analyzed, and lipid-lowering medication was recorded. OxLDL-ab levels were measured by ELISA. OxLDL-ab-based lipid indexes analyzed: oxLDL-ab/total cholesterol ratio; oxLDL-ab/LDL-c ratio; oxLDL-ab/high-density lipoprotein cholesterol (HDL-c) ratio; and oxLDL-ab/oxLDL ratio.

RESULTS

Lean-NAFLD patients presented 26.5% (9/34) of NASH. OxLDL-ab/HDL-c ratio (r = 0.570; n = 34; P = 0.001) correlated with NAS score and was the only variable associated with NASH in the multivariate analysis [odds ratio, OR, 1.10 (95% confidence interval, CI: 1.01-1.21); P = 0.039]. Severe steatosis was present in 41.2% (14/34) of lean-NAFLD patients. OxLDL-ab/HDL-c ratio was higher in patients with grade-III steatosis (54.9 (37.3-124.6)) than those with grade II (37.1 (20.2-71.1)) and grade I (17.7 (13.1-22.8)) (P = 0.018). Hepatocellular ballooning was present in 20.6% (7/34) of lean-NAFLD patients, and OxLDL-ab/HDL-c ratio (OR 1.03 [95% CI: 1.01-1.05]; P = 0.050) was independently associated with histological features. OxLDL-ab/HDL-c ratio was higher in patients with advanced fibrosis (39.8 (22.9-121.6) vs 17.7 (13.9-30.9); P = 0.025), increasing gradually with the fibrosis stage (P = 0.042) and remained in the final multivariate model [OR 1.05 (95% CI: 1.00-1.11); P = 0.05]. However, in obese-NAFLD patients, oxLDL/HDL-c ratio was not associated with histological features.

CONCLUSIONS

Oxidized low-density lipoprotein antibodies/high-density lipoprotein cholesterol ratio could represent an interesting biomarker associated with NASH, hepatocellular ballooning, and liver fibrosis, in lean patients. OxLDL-ab/HDL-c could play an important role for distinguishing patients with and without NAFLD complications.

Changing clinical profile and factors associated with liver enzyme abnormalities among HIV-infected persons

The spectrum of liver disease among HIV-infected patients is changing. In the era of antiretroviral therapy, opportunistic infections are diminishing and deranged liver function appears to be due usually to drug-induced liver injury, alcohol, non-alcoholic steatohepatitis (NASH) or chronic hepatitis B. To test this hypothesis, 98 HIV-positive patients with deranged liver function were compared with matched HIV-positive patients with normal liver function and likewise matched HIV-negative patients with normal liver function tests.

Lean NAFLD: An Underrecognized Outlier

Nonalcoholic fatty liver disease (NAFLD) is commonly diagnosed in obese or overweight individuals. However, lean individuals with NAFLD are not rare but represent one significant end of the phenotypic spectrum of NAFLD. Although initial observations between obese and lean NAFLD reveal some metabolic parallels, these associations vary widely given differences in study populations and metabolic parameters assessed. The role of body composition in risk assessment is significant and incompletely assessed during most clinical encounters. Recent multinational investigation reveals an increased mortality in lean individuals with NASH. Many aspects of lean NAFLD need further exploration including epidemiology, clinical risk assessment, histologic changes unique to lean NAFLD, genetic and pathophysiologic mechanisms predisposing at risk individuals, natural history and treatment strategies in this underrecognized population.

Insufficiency of phosphatidylethanolamine N-methyltransferase is risk for lean non-alcoholic steatohepatitis

Although obesity is undoubtedly major risk for non-alcoholic steatohepatitis (NASH), the presence of lean NASH patients with normal body mass index has been recognized. Here, we report that the insufficiency of phosphatidylethanolamine N-methyltransferase (PEMT) is a risk for the lean NASH. The Pemt−/− mice fed high fat-high sucrose (HFHS) diet were protected from diet-induced obesity and diabetes, while they demonstrated prominent steatohepatitis and developed multiple liver tumors. Pemt exerted inhibitory effects on p53-driven transcription by forming the complex with clathrin heavy chain and p53, and Pemt−/− mice fed HFHS diet demonstrated prominent apoptosis of hepatocytes. Furthermore, hypermethylation and suppressed mRNA expression of F-box protein 31 and hepatocyte nuclear factor 4α resulted in the prominent activation of cyclin D1. PEMT mRNA expression in liver tissues of NASH patients was significantly lower than those with simple steatosis and we postulated the distinct clinical entity of lean NASH with insufficiency of PEMT activities.