Homozygosity for the patatin-like phospholipase-3/adiponutrin I148M polymorphism influences liver fibrosis in patients with nonalcoholic fatty liver disease

Sex-specific effects of PNPLA3 I148M

Metabolic dysfunction-associated steatotic liver disease (MASLD, previously termed NAFLD, nonalcoholic fatty liver disease) is a complex multifactorial disease showing generally higher prevalence and severity in men than in women. With respect to women, men are also more prone to develop metabolic dysfunction-associated steatohepatitis, fibrosis and liver-related complications. Several genetic, hormonal, environmental and lifestyle factors may contribute to sex differences in MASLD development, progression and outcomes. However, after menopause, the sex-specific prevalence of MASLD shows an opposite trend between men and women, pointing to the relevance of oestrogen signalling in the sexual dimorphism of MASLD. The patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene, that encodes a triacylglycerol lipase that plays a crucial role in lipid metabolism, has emerged as a key player in the pathogenesis of MASLD, with the I148M variant being strongly associated with increased liver fat content and disease severity. Recent advances indicate that carrying the PNPLA3 I148M variant can be a risk factor for MASLD especially for women. To elucidate the molecular mechanisms underlying the sex-specific role of PNPLA3 I148M in the development of MASLD, several in vitro, ex vivo and in vivo models have been developed.

Phenotypes of Metabolic Dysfunction-Associated Steatotic Liver Disease-Associated Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) typically develops as a consequence of liver cirrhosis, but HCC epidemiology has evolved drastically in recent years. Metabolic dysfunction-associated steatotic liver disease (MASLD), including metabolic dysfunction-associated steatohepatitis, has emerged as the most common chronic liver disease worldwide and a leading cause of HCC. A substantial proportion of MASLD-associated HCC (MASLD-HCC) also can develop in patients without cirrhosis. The specific pathways that trigger carcinogenesis in this context are not elucidated completely, and recommendations for HCC surveillance in MASLD patients are challenging. In the era of precision medicine, it is critical to understand the processes that define the profiles of patients at increased risk of HCC in the MASLD setting, including cardiometabolic risk factors and the molecular targets that could be tackled effectively. Ideally, defining categories that encompass key pathophysiological features, associated with tailored diagnostic and treatment strategies, should facilitate the identification of specific MASLD-HCC phenotypes. In this review, we discuss MASLD-HCC, including its epidemiology and health care burden, the mechanistic data promoting MASLD, metabolic dysfunction-associated steatohepatitis, and MASLD-HCC. Its natural history, prognosis, and treatment are addressed specifically, as the role of metabolic phenotypes of MASLD-HCC as a potential strategy for risk stratification. The challenges in identifying high-risk patients and screening strategies also are discussed, as well as the potential approaches for MASLD-HCC prevention and treatment.

Use of PNPLA3, TM6SF2, and HSD17B13 for detection of fibrosis in MASLD in the general population

BACKGROUND

Genetic testing can be used to evaluate disease risk. We evaluated if the use of three Single Nucleotide Polymorphisms (SNPs), alone or combined into a genetic risk score (GRS), can aid identify significant fibrosis in subjects with metabolic dysfunction-associated steatotic liver disease (MASLD).

METHODS

We assessed three known risk variants: PNPLA3 rs738409, TM6SF2 rs58542926, and HSD17B13 rs72613567. The study included 414 adult individuals invited from the Danish population, who were defined as at-risk of MASLD due to elevated ALT and body mass index (BMI) >25 kg/m2. Participants were assessed clinically and by the Fibrosis-4 (FIB-4) index and Fibroscan.

RESULTS

In total, 17 participants (4.1 %) had alcohol-related liver disease, 79 (19.1 %) had no evidence of liver disease, and four (1.0 %) were diagnosed with other liver diseases, including malignant disease. The remaining 314 participants (75.8 %) were diagnosed with MASLD. Of the 27 who underwent a liver biopsy for suspected fibrosis, 15 had significant fibrosis (≥F2) and 12 had no/mild fibrosis (F0/F1). The GRS was not associated with significant fibrosis (p = 0.09) but PNPLA3 was with an odds ratio of 6.75 (95 % CI 1.29 - 50.7; p = 0.039) risk allele CG/GG versus CC. The diagnostic accuracy of PNPLA3 combined with an increased Fib-4 (>1.3) was excellent for detecting significant fibrosis with a sensitivity of 1.00 (95 % CI 0.72-1.00), but the specificity was no better than for FIB-4 alone.

CONCLUSIONS

This study found no evidence to support the use of GRS for diagnosing significant fibrosis in MASLD. However, the combination of PNPLA3 and Fib-4 increased sensitivity considerably. In addition, ALT remains a useful tool for screening diagnosing other liver diseases than MASLD.

Liver Fibrosis Assessed Via Noninvasive Tests Is Associated With Incident Heart Failure in a General Population Cohort

BACKGROUND & AIMS

The aim of this study was to determine whether liver fibrosis is associated with heart failure in a general population cohort, and if genetic polymorphisms (PNPLA3 rs738409; TM6SF2 rs58542926), linked to increased risk of liver fibrosis and decreased risk of coronary artery disease, modify this association.

METHODS

Using UK Biobank data, we prospectively examined the relationship between noninvasive fibrosis markers (nonalcoholic fatty liver disease [NAFLD] fibrosis score [NFS], Fibrosis-4 [FIB-4] and aspartate transaminase [AST] to platelet ratio index [APRI]) and incident hospitalization/death from heart failure (n = 413,860). Cox-regression estimated hazard ratios (HRs) for incident heart failure. Effects of PNPLA3 and TM6SF2 on the association between liver fibrosis and heart failure were estimated by stratifying for genotype and testing for an interaction between genotype and liver fibrosis using a likelihood ratio test.

RESULTS

A total of 12,527 incident cases of heart failure occurred over a median of 10.7 years. Liver fibrosis was associated with an increased risk of hospitalization or death from heart failure (multivariable adjusted high-risk NFS score HR, 1.59; 95% confidence interval [CI],1.47-1.76; P < .0001; FIB-4 HR, 1.69; 95% CI, 1.55-1.84; P < .0001; APRI HR, 1.85; 95% CI, 1.56-2.19; P < .0001; combined fibrosis scores HR, 1.90; 95% CI, 1.44-2.49; P < .0001). These associations persisted for people with metabolic dysfunction-associated steatotic liver disease (MASLD), MASLD with alcohol consumption (Met-ALD), and harmful alcohol consumption. PNPLA3 rs738409 GG and TM6SF2 rs58542926 TT did not attenuate the positive association between fibrosis markers and heart failure. For PNPLA3, a statistically significant interaction was found between PNPLA3 rs738409, FIB-4, APRI score, and heart failure.

CONCLUSION

In the general population, serum markers of liver fibrosis are associated with increased hospitalization/death from heart failure. Genetic polymorphisms associated with liver fibrosis were not positively associated with elevated heart failure risk.

Genetics of Metabolic Dysfunction-associated Steatotic Liver Disease: The State of Art Update

Recent advances in the genetics of metabolic dysfunction-associated steatotic liver disease (MASLD) are gradually revealing the mechanisms underlying the heterogeneity of the disease and have shown promising results in patient stratification. Genetic characterization of the disease has been rapidly developed using genome-wide association studies, exome-wide association studies, phenome-wide association studies, and whole exome sequencing. These advances have been powered by the increase in computational power, the development of new analytical algorithms, including some based on artificial intelligence, and the recruitment of large and well-phenotyped cohorts. This review presents an update on genetic studies that emphasize new biological insights from next-generation sequencing approaches. Additionally, we discuss innovative methods for discovering new genetic loci for MASLD, including rare variants. To comprehensively manage MASLD, it is important to stratify risks. Therefore, we present an update on phenome-wide association study associations, including extreme phenotypes. Additionally, we discuss whether polygenic risk scores and targeted sequencing are ready for clinical use. With particular focus on precision medicine, we introduce concepts such as the interplay between genetics and the environment in modulating genetic risk with lifestyle or standard therapies. A special chapter is dedicated to gene-based therapeutics. The limitations of approved pharmacological approaches are discussed, and the potential of gene-related mechanisms in therapeutic development is reviewed, including the decision to perform genetic testing in patients with MASLD.

An international multidisciplinary consensus on pediatric metabolic dysfunction-associated fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in children and adolescents, particularly those with obesity. NAFLD is considered a hepatic manifestation of the metabolic syndrome due to its close associations with abdominal obesity, insulin resistance, and atherogenic dyslipidemia. Experts have proposed an alternative terminology, metabolic dysfunction-associated fatty liver disease (MAFLD), to better reflect its pathophysiology. This study aimed to develop consensus statements and recommendations for pediatric MAFLD through collaboration among international experts.

METHODS

A group of 65 experts from 35 countries and six continents, including pediatricians, hepatologists, and endocrinologists, participated in a consensus development process. The process encompassed various aspects of pediatric MAFLD, including epidemiology, mechanisms, screening, and management.

FINDINGS

In round 1, we received 65 surveys from 35 countries and analyzed these results, which informed us that 73.3% of respondents agreed with 20 draft statements while 23.8% agreed somewhat. The mean percentage of agreement or somewhat agreement increased to 80.85% and 15.75%, respectively, in round 2. The final statements covered a wide range of topics related to epidemiology, pathophysiology, and strategies for screening and managing pediatric MAFLD.

CONCLUSIONS

The consensus statements and recommendations developed by an international expert panel serve to optimize clinical outcomes and improve the quality of life for children and adolescents with MAFLD. These findings emphasize the need for standardized approaches in diagnosing and treating pediatric MAFLD.

FUNDING

This work was funded by the National Natural Science Foundation of China (82070588, 82370577), the National Key R&D Program of China (2023YFA1800801), National High Level Hospital Clinical Research Funding (2022-PUMCH-C-014), the Wuxi Taihu Talent Plan (DJTD202106), and the Medical Key Discipline Program of Wuxi Health Commission (ZDXK2021007).

Metabolic Dysfunction-Associated Steatotic Liver Disease in People Living with HIV-Limitations on Antiretroviral Therapy Selection

Chronic liver disease is one of the main causes of morbidity and mortality in people living with HIV (PLWH). The increasing life expectancy of PLWH, effective treatment for viral hepatitis, and Western dietary patterns as well as the adverse effects of antiretroviral therapy (ART) have rendered metabolic dysfunction-associated steatotic liver disease (MASLD) the most common chronic liver disease in PLWH. The risk factors for MASLD in PLWH include traditional MASLD risk factors and additional virus-specific factors, including the adverse effects of ART. The management of patients suffering from HIV and MASLD is often challenging. Apart from the conventional management of MASLD, there are also certain limitations concerning the use of ART in this patient population. In general, the appropriate combination of antiretroviral drugs should be chosen to achieve the triad of effective viral suppression, avoidance of mitochondrial dysfunction, and deterrence of worsening the patient's metabolic profile. In the current review, we discuss the epidemiology of MASLD in PLWH, the risk factors, and the disease pathogenesis, as well as the limitations in the use of ART in this patient population, while practical recommendations on how to overcome these limitations are also given.

Exploring the impact of the PNPLA3 I148M variant on primary human hepatic stellate cells using 3D extracellular matrix models

BACKGROUND & AIMS

The PNPLA3 rs738409 C>G (encoding for I148M) variant is a risk locus for the fibrogenic progression of chronic liver diseases, a process driven by hepatic stellate cells (HSCs). We investigated how the PNPLA3 I148M variant affects HSC biology using transcriptomic data and validated findings in 3D-culture models.

METHODS

RNA sequencing was performed on 2D-cultured primary human HSCs and liver biopsies of individuals with obesity, genotyped for the PNPLA3 I148M variant. Data were validated in wild-type (WT) or PNPLA3 I148M variant-carrying HSCs cultured on 3D extracellular matrix (ECM) scaffolds from human healthy and cirrhotic livers, with/without TGFB1 or cytosporone B (Csn-B) treatment.

RESULTS

Transcriptomic analyses of liver biopsies and HSCs highlighted shared PNPLA3 I148M-driven dysregulated pathways related to mitochondrial function, antioxidant response, ECM remodelling and TGFB1 signalling. Analogous pathways were dysregulated in WT/PNPLA3-I148M HSCs cultured in 3D liver scaffolds. Mitochondrial dysfunction in PNPLA3-I148M cells was linked to respiratory chain complex IV insufficiency. Antioxidant capacity was lower in PNPLA3-I148M HSCs, while reactive oxygen species secretion was increased in PNPLA3-I148M HSCs and higher in bioengineered cirrhotic vs. healthy scaffolds. TGFB1 signalling followed the same trend. In PNPLA3-I148M cells, expression and activation of the endogenous TGFB1 inhibitor NR4A1 were decreased: treatment with the Csn-B agonist increased total NR4A1 in HSCs cultured in healthy but not in cirrhotic 3D scaffolds. NR4A1 regulation by TGFB1/Csn-B was linked to Akt signalling in PNPLA3-WT HSCs and to Erk signalling in PNPLA3-I148M HSCs.

CONCLUSION

HSCs carrying the PNPLA3 I148M variant have impaired mitochondrial function, antioxidant responses, and increased TGFB1 signalling, which dampens antifibrotic NR4A1 activity. These features are exacerbated by cirrhotic ECM, highlighting the dual impact of the PNPLA3 I148M variant and the fibrotic microenvironment in progressive chronic liver diseases.

IMPACT AND IMPLICATIONS

Hepatic stellate cells (HSCs) play a key role in the fibrogenic process associated with chronic liver disease. The PNPLA3 genetic mutation has been linked with increased risk of fibrogenesis, but its role in HSCs requires further investigation. Here, by using comparative transcriptomics and a novel 3D in vitro model, we demonstrate the impact of the PNPLA3 genetic mutation on primary human HSCs' behaviour, and we show that it affects the cell's mitochondrial function and antioxidant response, as well as the antifibrotic gene NR4A1. Our publicly available transcriptomic data, 3D platform and our findings on NR4A1 could facilitate the discovery of targets to develop more effective treatments for chronic liver diseases.

Global perspective on nonalcoholic fatty liver disease and nonalcoholic steatohepatitis - prevalence, clinical impact, economic implications and management strategies

BACKGROUND

The metabolically-based liver disease, nonalcoholic fatty liver disease (NAFLD), is the most common cause of chronic liver disease currently affecting 38% of the world's adult population. NAFLD can be progressive leading to nonalcoholic steatohepatitis (NASH), liver transplantation, liver cancer, liver-related mortality and is associated with decreased quality of life from impaired physical functioning and increased healthcare resource utilisation. However, screening for NAFLD is cost-prohibitive but screening for high risk NAFLD (NAFLD with F2 fibrosis or greater) is imperative.

AIM

To review the global perspective on NAFLD and NASH METHODS: We retrieved articles from PubMed using search terms NAFLD, prevalence, clinical burden, economic burden and management strategies.

RESULTS

NAFLD/NASH shows geographical variation across the globe. Highest prevalence rates are in South America and the Middle East and North Africa; lowest prevalence is in Africa. NAFLD's economic impact is from direct and indirect medical costs and loss in worker productivity. It is projected that, over the next two decades, the total cost of NAFLD and diabetes will exceed $1.5 trillion (USD). Risk stratification algorithms identifying "high risk NAFLD" were made following non-invasive tests for NAFLD identification and fibrosis development. These algorithms should be used in primary care and endocrinology settings so timely and appropriate interventions (lifestyle and cardiometabolic risk factor management) can be initiated.

CONCLUSIONS

To reduce the burgeoning burden of NAFLD/NASH, management should include risk stratification algorithms for accurate identification of patients, linkage to appropriate settings, and initiation of effective treatment regimens.

Drug repurposing in MASLD and MASH-cirrhosis: Targets and treatment approaches based on pathways analysis

Designing and predicting novel drug targets to accelerate drug discovery for treating metabolic dysfunction-associated steatohepatitis (MASH)-cirrhosis is a challenging task. The presence of superimposed (nested) and co-occurring clinical and histological phenotypes, namely MASH and cirrhosis, may partly explain this. Thus, in this scenario, each sub-phenotype has its own set of pathophysiological mechanisms, triggers, and processes. Here, we used gene/protein and set enrichment analysis to predict druggable pathways for the treatment of MASH-cirrhosis. Our findings indicate that the pathogenesis of MASH-cirrhosis can be explained by perturbations in multiple, simultaneous, and overlapping molecular processes. In this scenario, each sub-phenotype has its own set of pathophysiological mechanisms, triggers, and processes. Therefore, we used systems biology modeling to provide evidence that MASH and cirrhosis paradoxically present unique and distinct as well as common disease mechanisms, including a network of molecular targets. More importantly, pathway analysis revealed straightforward results consistent with modulation of the immune response, cell cycle control, and epigenetic regulation. In conclusion, the selection of potential therapies for MASH-cirrhosis should be guided by a better understanding of the underlying biological processes and molecular perturbations that progressively damage liver tissue and its underlying structure. Therapeutic options for patients with MASH may not necessarily be of choice for MASH cirrhosis. Therefore, the biology of the disease and the processes associated with its natural history must be at the forefront of the decision-making process.

Comparison of Wild-Type and High-risk PNPLA3 variants in a Human Biomimetic Liver Microphysiology System for Metabolic Dysfunction-associated Steatotic Liver Disease Precision Therapy

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a worldwide health epidemic with a global occurrence of approximately 30%. The pathogenesis of MASLD is a complex, multisystem disorder driven by multiple factors including genetics, lifestyle, and the environment. Patient heterogeneity presents challenges for developing MASLD therapeutics, creation of patient cohorts for clinical trials and optimization of therapeutic strategies for specific patient cohorts. Implementing pre-clinical experimental models for drug development creates a significant challenge as simple in vitro systems and animal models do not fully recapitulate critical steps in the pathogenesis and the complexity of MASLD progression. To address this, we implemented a precision medicine strategy that couples the use of our liver acinus microphysiology system (LAMPS) constructed with patient-derived primary cells. We investigated the MASLD-associated genetic variant PNPLA3 rs738409 (I148M variant) in primary hepatocytes, as it is associated with MASLD progression. We constructed LAMPS with genotyped wild type and variant PNPLA3 hepatocytes together with key non-parenchymal cells and quantified the reproducibility of the model. We altered media components to mimic blood chemistries, including insulin, glucose, free fatty acids, and immune activating molecules to reflect normal fasting (NF), early metabolic syndrome (EMS) and late metabolic syndrome (LMS) conditions. Finally, we investigated the response to treatment with resmetirom, an approved drug for metabolic syndrome-associated steatohepatitis (MASH), the progressive form of MASLD. This study using primary cells serves as a benchmark for studies using patient biomimetic twins constructed with patient iPSC-derived liver cells using a panel of reproducible metrics. We observed increased steatosis, immune activation, stellate cell activation and secretion of pro-fibrotic markers in the PNPLA3 GG variant compared to wild type CC LAMPS, consistent with the clinical characterization of this variant. We also observed greater resmetirom efficacy in PNPLA3 wild type CC LAMPS compared to the GG variant in multiple MASLD metrics including steatosis, stellate cell activation and the secretion of pro-fibrotic markers. In conclusion, our study demonstrates the capability of the LAMPS platform for the development of MASLD precision therapeutics, enrichment of patient cohorts for clinical trials, and optimization of therapeutic strategies for patient subgroups with different clinical traits and disease stages.

No association of NAFLD-related polymorphisms in PNPLA3 and TM6SF2 with all-cause and cardiovascular mortality in an Austrian population study

BACKGROUND AND AIMS

Single-nucleotide-polymorphisms in PNPLA3-rs738409 and the TM6SF2-rs58542926, associated with metabolic-dysfunction-associated fatty liver disease (MAFLD), have been discussed as potentially protective for cardiovascular diseases. Therefore, we aimed to study the associations of PNPLA3/TM6SF2 variants with MAFLD and cardiovascular risk in a population-based sample of asymptomatic patients.

METHODS

The study cohort comprised 1742 patients of European decent aged 45-80 years from a registry study undergoing screening colonoscopy for colorectal cancer between 2010 and 2014. SCORE2 and Framingham risk score calculated to assess cardiovascular risk. Data on survival were obtained from the national death registry RESULTS: Half of included patients were male (52%, 59 ± 10 years), 819 (47%) carried PNPLA3‑G and 278 (16%) TM6SF2-T-alleles. MAFLD (PNPLA3‑G-allele: 46% vs. 41%, p = 0.041; TM6SF2‑T-allele: 54% vs. 42%, p < 0.001) was more frequent in patients harbouring risk alleles with both showing independent associations with MAFLD on multivariable binary logistic regression analysis. While median Framingham risk score was lower in PNPLA3‑G-allele carriers (10 vs. 8, p = 0.011), SCORE2 and established cardiovascular diseases were similar across carriers vs. non-carriers of the respective risk-alleles. During a median follow-up of 9.1 years, neither PNPLA3‑G-allele nor TM6SF2‑T-allele was associated with overall nor with cardiovascular mortality.

CONCLUSION

Carriage of PNPLA3/TM6SF2 risk alleles could not be identified as significant factor for all-cause or cardiovascular mortality in asymptomatic middle-aged individuals undergoing screening colonoscopy.

Risk of major adverse liver outcomes among first-degree relatives of individuals with MASLD

BACKGROUND & AIMS

Previous studies have suggested an increased risk of major adverse liver outcomes (MALO) in relatives of patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, granular and longitudinal evidence is lacking on the future risk of MALO among family members of individuals with MASLD.

METHODS

We identified 3526 first-degree relatives (FDRs) and 11 079 general population comparators to 1328 patients with MASLD diagnosed between 1974 and 2021, with detailed clinical data, including liver histology in 71% of patients. MALO was defined through diagnostic coding for cirrhosis or its complications. Cox regression models were used to estimate adjusted hazard ratios (aHRs) for MALO among FDRs compared to general population comparators. Cumulative incidence accounting for competing risks was calculated.

RESULTS

During a median follow-up of 13.4 years, there were 65 (2%, 1.12/1000 person-years) and 225 (2%, 1.26/1000 person-years) MALO events in FDRs and general population comparators respectively. After adjusting for demographic factors and comorbidities, FDRs were at no increased risk of MALO (aHR = 0.99, 95% CI: 0.74-1.33). Increased relative rates of MALOs were, however, observed in some subgroups, including parents, although absolute risk estimates were low and comparable to the general population.

CONCLUSIONS

FDRs of patients with MASLD did not have a higher rate of incident MALO than the general population. Since the absolute risk of MALO in relatives of patients with MASLD was low, these results do not support systematic screening of MASLD-related fibrosis in relatives of patients with MASLD.

The Relationship between Pathogenesis and Possible Treatments for the MASLD-Cirrhosis Spectrum

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a term that entails a broad spectrum of conditions that vary in severity. Its development is influenced by multiple factors such as environment, microbiome, comorbidities, and genetic factors. MASLD is closely related to metabolic syndrome as it is caused by an alteration in the metabolism of fatty acids due to the accumulation of lipids because of an imbalance between its absorption and elimination in the liver. Its progression to fibrosis is due to a constant flow of fatty acids through the mitochondria and the inability of the liver to slow down this metabolic load, which generates oxidative stress and lipid peroxidation, triggering cell death. The development and progression of MASLD are closely related to unhealthy lifestyle habits, and nutritional epigenetic and genetic mechanisms have also been implicated. Currently, lifestyle modification is the first-line treatment for MASLD and nonalcoholic steatohepatitis; weight loss of ≥10% produces resolution of steatohepatitis and fibrosis regression. In many patients, body weight reduction cannot be achieved; therefore, pharmacological treatment should be offered in particular populations.

Investigating the Relationship Between Rare Genetic Variants and Fibrosis in Pediatric Nonalcoholic Fatty Liver Disease

Background and Aims

Nonalcoholic Fatty Liver Disease (NAFLD) is a complex human disease. Common genetic variation in the patatin-like phospholipase domain containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2) genes have been associated with an increased risk of developing NAFLD, nonalcoholic steatohepatitis (NASH), and fibrosis in adults. The role of rare genetic variants in the development and progression of NAFLD in children is not well known. We aimed to explore the role of rare genetic variants in pediatric patients with advanced fibrosis.

Methods

Whole exome sequencing data was generated for 229 pediatric patients diagnosed with NAFLD recruited from the NASH Clinical Research Network (NASH CRN). Case-control single variant and gene-based collapsing analyses were used to test for rare variants that were enriched or depleted within the pediatric NAFLD cohort specifically for advanced fibrosis (cases) versus those without fibrosis (controls) or six other histologic characteristics. Exome data from non-NAFLD population controls were also used for additional analyses. All results were adjusted for multiple testing using a Bonferroni correction.

Results

No genome-wide significant associations were found between rare variation and presence of advanced fibrosis or NASH, nor the severity of steatosis, inflammation, or hepatocellular ballooning. Significantly, no enrichment of rare variants in PNPLA3 or TM6SF2 was observed across phenotypes.

Conclusion

In a cohort of children with histologically proven NAFLD, no genome-wide significant associations were found between rare genetic variation and advanced fibrosis or six other histologic features. Of particular interest was the lack of association with genes of interest in adults: PNPLA3 and TM6SF2, though limitations in sample size may reduce the ability to detect associations, particularly with rare variation.

NAFLD Fibrosis Progression and Type 2 Diabetes: The Hepatic-Metabolic Interplay

The bidirectional relationship between type 2 diabetes and (non-alcoholic fatty liver disease) NAFLD is indicated by the higher prevalence and worse disease course of one condition in the presence of the other, but also by apparent beneficial effects observed in one, when the other is improved. This is partly explained by their belonging to a multisystemic disease that includes components of the metabolic syndrome and shared pathogenetic mechanisms. Throughout the progression of NAFLD to more advanced stages, complex systemic and local metabolic derangements are involved. During fibrogenesis, a significant metabolic reprogramming occurs in the hepatic stellate cells, hepatocytes, and immune cells, engaging carbohydrate and lipid pathways to support the high-energy-requiring processes. The natural history of NAFLD evolves in a variable and dynamic manner, probably due to the interaction of a variable number of modifiable (diet, physical exercise, microbiota composition, etc.) and non-modifiable (genetics, age, ethnicity, etc.) risk factors that may intervene concomitantly, or subsequently/intermittently in time. This may influence the risk (and rate) of fibrosis progression/regression. The recognition and control of the factors that determine a rapid progression of fibrosis (or its regression) are critical, as the fibrosis stages are associated with the risk of liver-related and all-cause mortality.

The ubiquitin E3 ligase BFAR promotes degradation of PNPLA3

A missense variant in patatin-like phospholipase domain-containing protein 3 [PNPLA3(I148M)] is the most impactful genetic risk factor for fatty liver disease (FLD). We previously showed that PNPLA3 is ubiquitylated and subsequently degraded by proteasomes and autophagosomes and that the PNPLA3(148M) variant interferes with this process. To define the machinery responsible for PNPLA3 turnover, we used small interfering (si)RNAs to inactivate components of the ubiquitin proteasome system. Inactivation of bifunctional apoptosis regulator (BFAR), a membrane-bound E3 ubiquitin ligase, reproducibly increased PNPLA3 levels in two lines of cultured hepatocytes. Conversely, overexpression of BFAR decreased levels of endogenous PNPLA3 in HuH7 cells. BFAR and PNPLA3 co-immunoprecipitated when co-expressed in cells. BFAR promoted ubiquitylation of PNPLA3 in vitro in a reconstitution assay using purified, epitope-tagged recombinant proteins. To confirm that BFAR targets PNPLA3, we inactivated Bfar in mice. Levels of PNPLA3 protein were increased twofold in hepatic lipid droplets of Bfar-/- mice with no associated increase in PNPLA3 mRNA levels. Taken together these data are consistent with a model in which BFAR plays a role in the post-translational degradation of PNPLA3. The identification of BFAR provides a potential target to enhance PNPLA3 turnover and prevent FLD.

Association of liver fibrosis with extrahepatic cancer in steatotic liver disease patients with PNPLA3 I148M GG genotype

The impacts of patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M-rs738409, methylenetetrahydrofolate reductase (MTHFR) Ala222Val-rs1801133, and aldehyde dehydrogenase 2 (ALDH2) Glu504Lys-rs671 on the outcomes of Taiwanese patients with steatotic liver disease (SLD) have remained elusive. An 8-year prospective cohort study of patients with (n = 546) and without (n = 580) SLD (controls) was undertaken in a Taiwanese tertiary care center. The 546 SLD patients comprised 306 (56.0%) men and 240 (44.0%) women with mean ages of 53.3 and 56.4 years, respectively. Compared with the controls, SLD patients had an increased frequency of the PNPLA3 I148M-rs738409 GG genotype (25.5 vs. 5.9%, p = 0.001). Among the SLD patients, 236 (43.1%) suffered cardiovascular events, 52 (9.5%) showed extrahepatic cancers, 13 (2.38%) experienced hepatic events, including hepatocellular carcinoma (n = 3, 0.5%) and liver cirrhosis (n = 8, 1.47%), and none died. The Fibrosis-4 (FIB-4) scores were associated with extrahepatic cancer (hazard ratio [HR] 1.325; 95% confidence interval [CI], 1.038-1.691) and cirrhosis development (HR 1.532; 95% CI, 1.055-2.224), and the PNPLA3 I148M-rs738409 G allele (β = 0.158, 95% CI, 0.054-0.325) was associated with the FIB-4 score. Stratified analyses showed that the impact of the FIB-4 score on extrahepatic cancer development was evident only in SLD patients with the PNPLA3 I148M-rs738409 GG genotype (HR 1.543; 95% CI, 1.195-1.993) and not in patients with the GC or CC genotype. Moreover, the ALDH2 Glu504Lys-rs671 G allele had a dose-dependent effect on alcoholism, and the MTHFR and ALDH2 genotypes were not significantly associated with SLD patient outcomes. In conclusion, special vigilance should be exercised for emerging extrahepatic cancer in SLD patients with the PNPLA3 I148M-rs738409 GG genotype and high FIB-4 scores.

IL32 downregulation lowers triglycerides and type I collagen in di-lineage human primary liver organoids

Steatotic liver disease (SLD) prevails as the most common chronic liver disease yet lack approved treatments due to incomplete understanding of pathogenesis. Recently, elevated hepatic and circulating interleukin 32 (IL-32) levels were found in individuals with severe SLD. However, the mechanistic link between IL-32 and intracellular triglyceride metabolism remains to be elucidated. We demonstrate in vitro that incubation with IL-32β protein leads to an increase in intracellular triglyceride synthesis, while downregulation of IL32 by small interfering RNA leads to lower triglyceride synthesis and secretion in organoids from human primary hepatocytes. This reduction requires the upregulation of Phospholipase A2 group IIA (PLA2G2A). Furthermore, downregulation of IL32 results in lower intracellular type I collagen levels in di-lineage human primary hepatic organoids. Finally, we identify a genetic variant of IL32 (rs76580947) associated with lower circulating IL-32 and protection against SLD measured by non-invasive tests. These data suggest that IL32 downregulation may be beneficial against SLD.

Prevalence and Determinants of Liver Disease in Relatives of Italian Patients With Advanced MASLD

BACKGROUND & AIMS

Metabolic dysfunction associated steatotic liver disease (MASLD) has a strong genetic component. The aim of this study was to examine noninvasively the prevalence of MASLD and of advanced fibrosis in relatives of patients with advanced MASLD and the risk factors for liver involvement, with a focus on the contribution of common genetic risk variants.

METHODS

We prospectively enrolled 98 consecutive probands with advanced fibrosis and/or hepatocellular carcinoma caused by MASLD and 160 nontwin first-degree relatives noninvasively screened for MASLD and advanced fibrosis at 4 Italian centers. We evaluated common genetic determinants and polygenic risk scores of liver disease.

RESULTS

Among relatives, prevalence of MASLD was 56.8% overall, whereas advanced fibrosis was observed in 14.4%. At multivariable analysis in relatives, MASLD was associated with body mass index (odds ratio [OR], 1.31 [1.18-1.46]) and tended to be associated with diabetes (OR, 5.21 [0.97-28.10]), alcohol intake (OR, 1.32 [0.98-1.78]), and with female sex (OR, 0.54 [0.23-1.15]), whereas advanced fibrosis was associated with diabetes (OR, 3.13 [1.16-8.45]) and nearly with body mass index (OR, 1.09 [1.00-1.19]). Despite that the PNPLA3 risk variant was enriched in probands (P = .003) and overtransmitted to relatives with MASLD (P = .045), evaluation of genetic risk variants and polygenic risk scores was not useful to guide noninvasive screening of advanced fibrosis in relatives.

CONCLUSIONS

We confirmed that about 1 in 7 relatives of patients with advanced MASLD has advanced fibrosis, supporting clinical recommendations to perform family screening in this setting. Genetic risk variants contributed to liver disease within families but did not meaningfully improve fibrosis risk stratification.

The Intersection of Genetic Factors, Aberrant Nutrient Metabolism and Oxidative Stress in the Progression of Cardiometabolic Disease

Cardiometabolic disease (CMD), which encompasses metabolic-associated fatty liver disease (MAFLD), chronic kidney disease (CKD) and cardiovascular disease (CVD), has been increasing considerably in the past 50 years. CMD is a complex disease that can be influenced by genetics and environmental factors such as diet. With the increased reliance on processed foods containing saturated fats, fructose and cholesterol, a mechanistic understanding of how these molecules cause metabolic disease is required. A major pathway by which excessive nutrients contribute to CMD is through oxidative stress. In this review, we discuss how oxidative stress can drive CMD and the role of aberrant nutrient metabolism and genetic risk factors and how they potentially interact to promote progression of MAFLD, CVD and CKD. This review will focus on genetic mutations that are known to alter nutrient metabolism. We discuss the major genetic risk factors for MAFLD, which include Patatin-like phospholipase domain-containing protein 3 (PNPLA3), Membrane Bound O-Acyltransferase Domain Containing 7 (MBOAT7) and Transmembrane 6 Superfamily Member 2 (TM6SF2). In addition, mutations that prevent nutrient uptake cause hypercholesterolemia that contributes to CVD. We also discuss the mechanisms by which MAFLD, CKD and CVD are mutually associated with one another. In addition, some of the genetic risk factors which are associated with MAFLD and CVD are also associated with CKD, while some genetic risk factors seem to dissociate one disease from the other. Through a better understanding of the causative effect of genetic mutations in CMD and how aberrant nutrient metabolism intersects with our genetics, novel therapies and precision approaches can be developed for treating CMD.

Effect of donor HSD17B13 genotype on patient survival after liver transplant: a retrospective cohort study

Background

Several genetic variants are associated with chronic liver disease. The role of these variants in outcomes after liver transplantation (LT) is uncertain. The aim of this study was to determine if donor genotype at risk-associated variants in PNPLA3 (rs738409 C>G, p.I148M) and HSD17B13 (rs72613567 T>TA; rs80182459, p.A192Lfs∗8) influences post-LT survival.

Methods

In this retrospective cohort study, data on 2346 adults who underwent first-time LT between January 1, 1999 and June 30, 2020 and who had donor DNA samples available at five large Transplant Immunology Laboratories in Texas, USA, were obtained from the United Network for Organ Sharing (UNOS). Duplicates, patients with insufficient donor DNA for genotyping, those who were <18 years of age at the time of transplant, had had a previous transplant or had missing genotype data were excluded. The primary outcomes were patient and graft survival after LT. The association between donor genotype and post-LT survival was examined using Kaplan-Meier method and multivariable-adjusted Cox proportional hazards models.

Findings

Median age of LT recipients was 57 [interquartile range (IQR), 50-62] years; 837 (35.7%) were women; 1362 (58.1%) White, 713 (30.4%) Hispanic, 182 (7.8%) Black/African-American. Median follow-up time was 3.95 years. Post-LT survival was not affected by donor PNPLA3 genotype but was significantly reduced among recipients of livers with two HSD17B13 loss-of-function (LoF) variants compared to those receiving livers with no HSD17B13 LoF alleles (unadjusted one-year survival: 82.6% vs 93.9%, P < 0.0001; five-year survival: 73.1% vs 82.9%, P = 0.0017; adjusted hazard ratio [HR], 2.25; 95% CI, 1.61-3.15 after adjustment for recipient age, sex, and self-reported ethnicity). Excess mortality was restricted to those receiving steroid induction immunosuppression (crude 90-day post-LT mortality, 9.3% [95% CI, 1.9%-16.1%] vs 1.9% [95% CI, 0.9%-2.9%] in recipients of livers with two vs no HSD17B13 LoF alleles, P = 0.0012; age, sex, and ethnicity-adjusted HR, 2.85; 95% CI, 1.72-4.71, P < 0.0001). No reduction was seen among patients who did not receive steroid induction (90-day mortality 3.1% [95% CI, 0%-7.3%] vs 2% [95% CI, 0.9%-3.1%], P = 0.65; adjusted HR, 1.17; 95% CI, 0.66-2.08, P = 0.60).

Interpretation

Donor HSD17B13 genotype adversely affects post-LT survival in patients receiving steroid induction. Additional studies are required to confirm this association.

Funding

The National Institutes of Health and American Society of Transplant Surgeons Collaborative Scientist Grant.

Impact of PNPLA3 rs738409 Polymorphism on the Development of Liver-Related Events in Patients With Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is a complex disease, resulting from the interplay between environmental determinants and genetic variations. Single nucleotide polymorphism rs738409 C>G in the PNPLA3 gene is associated with hepatic fibrosis and with higher risk of developing hepatocellular carcinoma. Here, we analyzed a longitudinal cohort of biopsy-proven NAFLD subjects with the aim to identify individuals in whom genetics may have a stronger impact on disease progression.

METHODS

We retrospectively analyzed 756 consecutive, prospectively enrolled biopsy-proven NAFLD subjects from Italy, United Kingdom, and Spain who were followed for a median of 84 months (interquartile range, 65-109 months). We stratified the study cohort according to sex, body mass index (BMI)

RESULTS

Overall, the median age was 48 years and most individuals were men (64.7%). The PNPLA3 rs738409 genotype was CC in 235 (31.1%), CG in 328 (43.4%), and GG in 193 (25.5%) patients. At univariate analysis, the PNPLA3 GG risk genotype was associated with female sex and inversely related to BMI (odds ratio, 1.6; 95% confidence interval, 1.1-2.2; P = .006; and odds ratio, 0.97; 95% confidence interval, 0.94-0.99; P = .043, respectively). Specifically, PNPLA3 GG risk homozygosis was more prevalent in female vs male individuals (31.5% vs 22.3%; P = .006) and in nonobese compared with obese NAFLD subjects (50.0% vs 44.2%; P = .011). Following stratification for age, sex, and BMI, we observed an increased incidence of liver-related events in the subgroup of nonobese women older than 50 years of age carrying the PNPLA3 GG risk genotype (log-rank test, P = .0047).

CONCLUSIONS

Nonobese female patients with NAFLD 50 years of age and older, and carrying the PNPLA3 GG risk genotype, are at higher risk of developing liver-related events compared with those with the wild-type allele (CC/CG). This finding may have implications in clinical practice for risk stratification and personalized medicine.

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Key Words

• Liver-Related Outcomes
• NAFLD
• NASH
• PNPLA3

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MESH Headings

• Humans
• Female
• Male
• Middle Aged
• Non-alcoholic Fatty Liver Disease/complications
• Non-alcoholic Fatty Liver Disease/genetics
• Non-alcoholic Fatty Liver Disease/epidemiology
• Carcinoma, Hepatocellular/epidemiology
• Carcinoma, Hepatocellular/genetics
• Carcinoma, Hepatocellular/complications
• Retrospective Studies
• Esophageal and Gastric Varices/complications
• Gastrointestinal Hemorrhage/complications
• Genotype
• Polymorphism, Single Nucleotide
• Liver Neoplasms/epidemiology
• Liver Neoplasms/genetics
• Liver Neoplasms/complications
• Genetic Predisposition to Disease

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Affiliation(s)

Chiara Rosso Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Gian Paolo Caviglia Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Giovanni Birolo Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Angelo Armandi Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy; Metabolic Liver Disease Research Program, I. Department of Medicine, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
Grazia Pennisi Sezione di Gastroenterologia, PROMISE, Università di Palermo, Palermo, Italy
Serena Pelusi Precision Medicine, Department of Transfusion Medicine, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
Ramy Younes Boehringer Ingelheim International, GmbH, Ingelheim, Germany
Antonio Liguori Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy
Nuria Perez-Diaz-Del-Campo Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Aurora Nicolosi Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Olivier Govaere Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
Gabriele Castelnuovo Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Antonella Olivero Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Maria Lorena Abate Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Davide Giuseppe Ribaldone Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Piero Fariselli Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy
Luca Valenti Precision Medicine, Department of Transfusion Medicine, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy; Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
Luca Miele Dipartimento Universitario Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Rome, Italy; Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Gemelli IRCCS, Rome, Italy
Salvatore Petta Sezione di Gastroenterologia, PROMISE, Università di Palermo, Palermo, Italy
Manuel Romero-Gomez UCM Digestive Diseases and SeLiver Group, Virgen del Rocío University Hospital, Institute of Biomedicine of Seville, University of Seville, Seville, Spain
Quentin M Anstee Newcastle Liver Research Group, Translational & Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom; Newcastle NIHR Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, United Kingdom
Elisabetta Bugianesi Division of Gastroenterology and Hepatology, Department of Medical Sciences, University of Turin, Turin, Italy.

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The PNPLA3 I148M variant increases ketogenesis and decreases hepatic de novo lipogenesis and mitochondrial function in humans

The PNPLA3 I148M variant is the major genetic risk factor for all stages of fatty liver disease, but the underlying pathophysiology remains unclear. We studied the effect of this variant on hepatic metabolism in homozygous carriers and non-carriers under multiple physiological conditions with state-of-the-art stable isotope techniques. After an overnight fast, carriers had higher plasma β-hydroxybutyrate concentrations and lower hepatic de novo lipogenesis (DNL) compared to non-carriers. After a mixed meal, fatty acids were channeled toward ketogenesis in carriers, which was associated with an increase in hepatic mitochondrial redox state. During a ketogenic diet, carriers manifested increased rates of intrahepatic lipolysis, increased plasma β-hydroxybutyrate concentrations, and decreased rates of hepatic mitochondrial citrate synthase flux. These studies demonstrate that homozygous PNPLA3 I148M carriers have hepatic mitochondrial dysfunction leading to reduced DNL and channeling of carbons to ketogenesis. These findings have implications for understanding why the PNPLA3 variant predisposes to progressive liver disease.

Found in translation-Fibrosis in metabolic dysfunction-associated steatohepatitis (MASH)

Metabolic dysfunction-associated steatohepatitis (MASH) is a severe form of liver disease that poses a global health threat because of its potential to progress to advanced fibrosis, leading to cirrhosis and liver cancer. Recent advances in single-cell methodologies, refined disease models, and genetic and epigenetic insights have provided a nuanced understanding of MASH fibrogenesis, with substantial cellular heterogeneity in MASH livers providing potentially targetable cell-cell interactions and behavior. Unlike fibrogenesis, mechanisms underlying fibrosis regression in MASH are still inadequately understood, although antifibrotic targets have been recently identified. A refined antifibrotic treatment framework could lead to noninvasive assessment and targeted therapies that preserve hepatocellular function and restore the liver's architectural integrity.

Genetic Predictors of Comorbid Course of COVID-19 and MAFLD: A Comprehensive Analysis

Metabolic-associated fatty liver disease (MAFLD) and its potential impact on the severity of COVID-19 have gained significant attention during the pandemic. This review aimed to explore the genetic determinants associated with MAFLD, previously recognized as non-alcoholic fatty liver disease (NAFLD), and their potential influence on COVID-19 outcomes. Various genetic polymorphisms, including PNPLA3 (rs738409), GCKR (rs780094), TM6SF2 (rs58542926), and LYPLAL1 (rs12137855), have been investigated in relation to MAFLD susceptibility and progression. Genome-wide association studies and meta-analyses have revealed associations between these genetic variants and MAFLD risk, as well as their effects on lipid metabolism, glucose regulation, and liver function. Furthermore, emerging evidence suggests a possible connection between these MAFLD-associated polymorphisms and the severity of COVID-19. Studies exploring the association between indicated genetic variants and COVID-19 outcomes have shown conflicting results. Some studies observed a potential protective effect of certain variants against severe COVID-19, while others reported no significant associations. This review highlights the importance of understanding the genetic determinants of MAFLD and its potential implications for COVID-19 outcomes. Further research is needed to elucidate the precise mechanisms linking these genetic variants to disease severity and to develop gene profiling tools for the early prediction of COVID-19 outcomes. If confirmed as determinants of disease severity, these genetic polymorphisms could aid in the identification of high-risk individuals and in improving the management of COVID-19.

Programmed cell death 1 genetic variant and liver damage in nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Programmed cell death 1/programmed cell death-ligand 1 (PD-1/PDL-1) axis has been reported to modulate liver inflammation and progression to hepatocellular carcinoma (HCC) in patients with nonalcoholic fatty liver disease (NAFLD). Here, we examined whether the PDCD1 variation is associated with NAFLD severity in individuals with liver biopsy.

METHODS

We examined the impact of PDCD1 gene variants on HCC, as robust severe liver disease phenotype in UK Biobank participants. The strongest genetic association with the rs13023138 G>C variation was subsequently tested for association with liver damage in 2889 individuals who underwent liver biopsy for suspected nonalcoholic steatohepatitis (NASH). Hepatic transcriptome was examined by RNA-Seq in a subset of NAFLD individuals (n = 121). Transcriptomic and deconvolution analyses were performed to identify biological pathways modulated by the risk allele.

RESULTS

The rs13023138 C>G showed the most robust association with HCC in UK Biobank (p = 5.28E-4, OR = 1.32, 95% CI [1.1, 1.5]). In the liver biopsy cohort, rs13023138 G allele was independently associated with severe steatosis (OR 1.17, 95% CI 1.02-1.34; p = .01), NASH (OR 1.22, 95% CI 1.09-1.37; p < .001) and advanced fibrosis (OR 1.26, 95% CI 1.06-1.50; p = .007). At deconvolution analysis, rs13023138 G>C allele was linked to higher hepatic representation of M1 macrophages, paralleled by upregulation of pathways related to inflammation and higher expression of CXCR6.

CONCLUSIONS

The PDCD1 rs13023138 G allele was associated with HCC development in the general population and with liver disease severity in patients at high risk of NASH.

Long-term hypercaloric diet exacerbates metabolic liver disease in PNPLA3 I148M animals

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is a major health burden associated with the metabolic syndrome leading to liver fibrosis, cirrhosis and ultimately liver cancer. In humans, the PNPLA3 I148M polymorphism of the phospholipase patatin-like phospholipid domain containing protein 3 (PNPLA3) has a well-documented impact on metabolic liver disease. In this study, we used a mouse model mimicking the human PNPLA3 I148M polymorphism in a long-term high fat diet (HFD) experiment to better define its role for NAFLD progression.

METHODS

Male mice bearing wild-type Pnpla3 (Pnpla3WT ), or the human polymorphism PNPLA3 I148M (Pnpla3148M/M ) were subjected to HFD feeding for 24 and 52 weeks. Further analysis concerning basic phenotype, inflammation, proliferation and cell death, fibrosis and microbiota were performed in each time point.

RESULTS

After 52 weeks HFD Pnpla3148M/M animals had more liver fibrosis, enhanced numbers of inflammatory cells as well as increased Kupffer cell activity. Increased hepatocyte cell turnover and ductular proliferation were evident in HFD Pnpla3148M/M livers. Microbiome diversity was decreased after HFD feeding, changes were influenced by HFD feeding (36%) and the PNPLA3 I148M genotype (12%). Pnpla3148M/M mice had more faecal bile acids. RNA-sequencing of liver tissue defined an HFD-associated signature, and a Pnpla3148M/M specific pattern, which suggests Kupffer cell and monocytes-derived macrophages as significant drivers of liver disease progression in Pnpla3148M/M animals.

CONCLUSION

With long-term HFD feeding, mice with the PNPLA3 I148M genotype show exacerbated NAFLD. This finding is linked to PNPLA3 I148M-specific changes in microbiota composition and liver gene expression showing a stronger inflammatory response leading to enhanced liver fibrosis progression.

Influence of the Bile Acid Transporter Genes ABCB4, ABCB8, and ABCB11 and the Farnesoid X Receptor on the Response to Ursodeoxycholic Acid in Patients with Nonalcoholic Steatohepatitis

The prevalence of NAFLD and NASH is increasing worldwide, and there is no approved medical treatment until now. Evidence has emerged that interfering with bile acid metabolism may lead to improvement in NASH. In this study, 28 patients with elevated cholestatic liver function tests (especially GGT) were screened for bile acid gene polymorphisms and treated with UDCA. All patients had a bile acid gene polymorphism in ABCB4 or ABCB11. Treatment with UDCA for 12 months significantly reduced GGT in all patients and ALT in homozygous patients. No difference in fibrosis was observed using FIb-4, NFS, and transient elastography (TE). PNPLA3 and TM6SF2 were the most common NASH-associated polymorphisms, and patients with TM6SF2 showed a significant reduction in GGT and ALT with the administration of UDCA. In conclusion, NASH patients with elevated GGT should be screened for bile acid gene polymorphisms, as UDCA therapy may improve liver function tests. However, no difference in clinical outcomes, such as progression to cirrhosis, has been observed using non-invasive tests (NITs).

Dual targeting of hepatocyte DGAT2 and stellate cell FASN alleviates nonalcoholic steatohepatitis in mice

Nonalcoholic steatohepatitis (NASH) is a malady of multiple cell types associated with hepatocyte triglyceride (TG) accumulation, macrophage inflammation, and stellate cell-induced fibrosis, with no approved therapeutics yet available. Here, we report that stellate cell fatty acid synthase (FASN) in de novo lipogenesis drives the autophagic flux that is required for stellate cell activation and fibrotic collagen production. Further, we employ a dual targeting approach to NASH that selectively depletes collagen through selective stellate cell knockout of FASN (using AAV9-LRAT Cre in FASNfl/fl mice), while lowering hepatocyte triglyceride by depleting DGAT2 with a GalNac-conjugated, fully chemically modified siRNA. DGAT2 silencing in hepatocytes alone or in combination with stellate cell FASNKO reduced liver TG accumulation in a choline-deficient NASH mouse model, while FASNKO in hepatocytes alone (using AAV8-TBG Cre in FASNfl/fl mice) did not. Neither hepatocyte DGAT2 silencing alone nor FASNKO in stellate cells alone decreased fibrosis (total collagen), while loss of both DGAT2 plus FASN caused a highly significant attenuation of NASH. These data establish proof of concept that dual targeting of DGAT2 plus FASN alleviates NASH progression in mice far greater than targeting either gene product alone.

Association of non-high-density lipoprotein cholesterol trajectories with the development of non-alcoholic fatty liver disease: an epidemiological and genome-wide association study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) shares common risk factors with cardiovascular diseases. Effects of longitudinal trends in non-high-density lipoprotein (non-HDL) cholesterol on NAFLD development are not understood. This study aimed to assess the relationship between non-HDL cholesterol trajectories and the incidence of NAFLD and to identify genetic differences contributing to NAFLD development between non-HDL cholesterol trajectory groups.

METHODS

We analyzed data from 2203 adults (aged 40-69 years) who participated in the Korean Genome and Epidemiology Study. During the 6-year exposure periods, participants were classified into an increasing non-HDL cholesterol trajectory group (n = 934) or a stable group (n = 1269). NAFLD was defined using a NAFLD-liver fat score > -0.640. Multiple Cox proportional hazard regression analysis estimated the hazard ratio (HR) and the 95% confidence interval (CI) for the incidence of NAFLD in the increasing group compared with the stable group.

RESULTS

A genome-wide association study identified significant single-nucleotide polymorphisms (SNPs) associated with NAFLD. During the median 7.8-year of event accrual period, 666 (30.2%) newly developed NAFLD cases were collected. Compared with the stable non-HDL group, the adjusted HR (95% CI) for the incidence of NAFLD in the increasing non-HDL cholesterol group was 1.46 (1.25-1.71). Although there were no significant SNPs, the polygenic risk score was highest in the increasing group, followed by the stable and control groups.

CONCLUSION

Our study indicates that lifestyle or environmental factors have a greater effect size than genetic factors in NAFLD progression risk. Lifestyle modification could be an effective prevention strategy for NAFLD for people with elevated non-HDL cholesterol.

Liver Fibrosis in Non-Alcoholic Fatty Liver Disease and Progression to Hepatocellular Carcinoma in Patients with Inflammatory Bowel Disease: A Systematic Review

The aim of the systematic review is to assess the prevalence and risk factors of liver fibrosis in patients with Inflammatory Bowel Disease (IBD) and Non-Alcoholic Fatty Liver Disease (NAFLD) and to discuss the role of liver fibrosis in the progression to hepatocellular carcinoma (HCC). We performed a structured search in PubMed, Web of Science, Embase, and Scopus up to 3 March 2023 to identify observational studies reporting liver fibrosis in patients with NAFLD and IBD. Quality of studies was assessed using the Newcastle-Ottawa Scale (NOS) score. A total of 23 studies met our inclusion criteria, including 629,781 patients. A total of 10 cross-sectional, 3 case-control, and 10 cohort studies were included. Fourteen studies had a NOS score ≥ 7 points. NAFLD was diagnosed in 2162/6332 (34.1%) IBD participants. However, NAFLD diagnosis was established in 924/2962 (31.2%) healthy individuals without IBD. Advanced liver fibrosis was found in 116 (11.6%) of 992 IBD patients with NAFLD. Most studies found an association between NAFLD and classic cardiovascular risk factors such as older age, male sex, higher BMI, diabetes, hypertension and dyslipidemia. In addition, metabolic syndrome features were also associated with an increased risk of significant and advanced liver fibrosis. Although no strong association between NAFLD and IBD therapy was reported, some studies associated NAFLD with IBD diagnosis, Crohn's Disease, a complicated course of IBD, disease activity, and IBD duration. Advanced liver fibrosis was also associated with Crohn's disease in several studies. In conclusion, NAFLD and advanced liver fibrosis are prevalent and clinically relevant extraintestinal manifestations, so its diagnosis and potential progression to HCC should be carefully considered in daily clinical practice.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Obesity, non-alcoholic fatty liver disease and hepatocellular carcinoma: current status and therapeutic targets

Obesity is a global epidemic and overwhelming evidence indicates that it is a risk factor for numerous cancers, including hepatocellular carcinoma (HCC), the third leading cause of cancer-related deaths worldwide. Obesity-associated hepatic tumorigenesis develops from nonalcoholic fatty liver disease (NAFLD), progressing to nonalcoholic steatohepatitis (NASH), cirrhosis and ultimately to HCC. The rising incidence of obesity is resulting in an increased prevalence of NAFLD and NASH, and subsequently HCC. Obesity represents an increasingly important underlying etiology of HCC, in particular as the other leading causes of HCC such as hepatitis infection, are declining due to effective treatments and vaccines. In this review, we provide a comprehensive overview of the molecular mechanisms and cellular signaling pathways involved in the pathogenesis of obesity-associated HCC. We summarize the preclinical experimental animal models available to study the features of NAFLD/NASH/HCC, and the non-invasive methods to diagnose NAFLD, NASH and early-stage HCC. Finally, since HCC is an aggressive tumor with a 5-year survival of less than 20%, we will also discuss novel therapeutic targets for obesity-associated HCC and ongoing clinical trials.

Advances in the genetics of nonalcoholic fatty liver disease

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the United States and has a strong heritable component. Advances in understanding the genetic underpinnings of NAFLD have revealed important insights into NAFLD pathogenesis, prognosis, and potential therapeutic targets. The purpose of this review is to summarize data on common and rare variants associated with NAFLD, combining risk variants into polygenic scores to predict NAFLD and cirrhosis as well as emerging evidence on using gene silencing as a novel therapeutic target in NAFLD.

RECENT FINDINGS

Protective variants in HSD17B13, MARC1 and CIDEB have been identified and a confer 10-50% lower risk of cirrhosis. Together, these as well as other NAFLD risk variants, including those in PNPLA3 and TM6SF2, can be combined to create polygenic risk scores associated with liver fat, cirrhosis, and hepatocellular carcinoma. Genomic analysis of extreme phenotypes including patients with lean NAFLD without visceral adiposity may uncover rare monogenic disorders with pathogenic and therapeutic implications and gene silencing strategies targeting HSD17B13 and PNPLA3 are being evaluated in early phase human studies as treatments for NAFLD.

SUMMARY

Advances in our understanding of the genetics of NAFLD will enable clinical risk stratification and yield potential therapeutic targets.

PNPLA3 Genotype and Diabetes Identify Patients With Nonalcoholic Fatty Liver Disease at High Risk of Incident Cirrhosis

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) can progress to cirrhosis and hepatic decompensation, but whether genetic variants influence the rate of progression to cirrhosis or are useful in risk stratification among patients with NAFLD is uncertain.

METHODS

We included participants from 2 independent cohorts, they Michigan Genomics Initiative (MGI) and UK Biobank (UKBB), who had NAFLD defined by elevated alanine aminotransferase (ALT) levels in the absence of alternative chronic liver disease. The primary predictors were genetic variants and metabolic comorbidities associated with cirrhosis. We conducted time-to-event analyses using Fine-Gray competing risk models.

RESULTS

We included 7893 and 46,880 participants from MGI and UKBB, respectively. In univariable analysis, PNPLA3-rs738409-GG genotype, diabetes, obesity, and ALT of ≥2× upper limit of normal were associated with higher incidence rate of cirrhosis in both MGI and UKBB. PNPLA3-rs738409-GG had additive effects with clinical risk factors including diabetes, obesity, and ALT elevations. Among patients with indeterminate fibrosis-4 (FIB4) scores (1.3-2.67), those with diabetes and PNPLA3-rs738409-GG genotype had an incidence rate of cirrhosis comparable to that of patients with high-risk FIB4 scores (>2.67) and 2.9-4.8 times that of patients with diabetes but CC/CG genotypes. In contrast, FIB4 <1.3 was associated with an incidence rate of cirrhosis significantly lower than that of FIB4 of >2.67, even in the presence of clinical risk factors and high-risk PNPLA3 genotype.

CONCLUSIONS

PNPLA3-rs738409 genotype and diabetes identified patients with NAFLD currently considered indeterminate risk (FIB4 1.3-2.67) who had a similar risk of cirrhosis as those considered high-risk (FIB4 >2.67). PNPLA3 genotyping may improve prognostication and allow for prioritization of intensive intervention.

Extrahepatic Outcomes of Nonalcoholic Fatty Liver Disease: Cardiovascular Diseases

Patients with nonalcoholic fatty liver disease (NAFLD) are at high risk of cardiovascular disease, including carotid atherosclerosis, coronary artery disease, heart failure, and arrhythmias. The risk is partially due to shared risk factors, but it may vary according to liver injury. A fatty liver may induce an atherogenic profile, the local necro-inflammatory changes of nonalcoholic steatohepatitis may enhance systemic metabolic inflammation, and fibrogenesis can run parallel in the liver and in the myocardium and precedes heart failure. The detrimental impact of a Western diet combines with polymorphisms in genes associated with atherogenic dyslipidemia. Shared clinical/diagnostic algorithms are needed to manage the cardiovascular risk in NAFLD.

Fatty Liver Disease, Metabolism and Alcohol Interplay: A Comprehensive Review

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, and its incidence has been increasing in recent years because of the high prevalence of obesity and metabolic syndrome in the Western population. Alcohol-related liver disease (ArLD) is the most common cause of cirrhosis and constitutes the leading cause of cirrhosis-related deaths worldwide. Both NAFLD and ArLD constitute well-known causes of liver damage, with some similarities in their pathophysiology. For this reason, they can lead to the progression of liver disease, being responsible for a high proportion of liver-related events and liver-related deaths. Whether ArLD impacts the prognosis and progression of liver damage in patients with NAFLD is still a matter of debate. Nowadays, the synergistic deleterious effect of obesity and diabetes is clearly established in patients with ArLD and heavy alcohol consumption. However, it is still unknown whether low to moderate amounts of alcohol are good or bad for liver health. The measurement and identification of the possible synergistic deleterious effect of alcohol consumption in the assessment of patients with NAFLD is crucial for clinicians, since early intervention, advising abstinence and controlling cardiovascular risk factors would improve the prognosis of patients with both comorbidities. This article seeks to perform a comprehensive review of the pathophysiology of both disorders and measure the impact of alcohol consumption in patients with NAFLD.

PNPLA3 genotypes modify the adverse effect of the total energy intake on high-risk nonalcoholic steatohepatitis development

BACKGROUND

The relationship between diet and risk genotypes in nonalcoholic steatohepatitis (NASH) development and fibrosis progression in patients with nonalcoholic fatty liver disease (NAFLD) remains unclear.

OBJECTIVE

We aimed to investigate the effects of diet on NASH development and fibrosis progression in patients with NAFLD stratified by the PNPLA3 genotype.

METHODS

We performed a prospective study in a cohort of patients with biopsy-confirmed NAFLD. Histologic deterioration was obtained using serial transient elastography at every 1 or 2 y. The primary outcome was fibrosis progression, and the secondary outcome was development of high-risk NASH, defined as FibroScan-aspartate aminotransferase score ≥0.67 during the follow-up of patients with nonalcoholic fatty liver at the baseline. Dietary intake was evaluated using a semiquantitative food frequency questionnaire.

RESULTS

The primary outcome was observed in 42 (29.0%) of the 145 patients during a median follow-up of 49 mo; neither the total energy intake nor each macronutrient intake significantly affected the primary outcome occurrence. Conversely, the total energy intake (HR per 1-SD: 3.03; 95% CI: 1.31, 7.01) and the PNPLA3 rs738409 genotype [HR per 1 risk allele (G): 2.06; 95% CI: 1.11, 3.83)] were independent risk factors for high-risk NASH. The significant interaction between the total energy intake and PNPLA3 genotype was noted in developing high-risk NASH (P = 0.044). As the number of PNPLA3 risk alleles decreased, the effect of the total energy intake on high-risk NASH increased; the HR per 1-SD increment in total energy intake was 1.52 (95% CI: 0.42, 5.42), 3.54 (95% CI: 1.23, 10.18), and 8.27 (95% CI: 1.20, 57.23) for the GG, CG, and CC genotypes, respectively.

CONCLUSIONS

The total energy intake adversely affected the development of high-risk NASH in patients with biopsy-confirmed NAFLD. The effect was more prominent in patients without the PNPLA3 risk allele, highlighting the importance of personalized dietary interventions in NAFLD treatment.

Changes in abdominal adipose tissue depots assessed by MRI correlate with hepatic histologic improvement in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Non-alcoholic steatohepatitis (NASH) is prevalent in adults with obesity and can progress to cirrhosis. In a secondary analysis of prospectively acquired data from the multicenter, randomized, placebo-controlled FLINT trial, we investigated the relationship between reduction in adipose tissue compartment volumes and hepatic histologic improvement.

METHODS

Adult participants in the FLINT trial with paired liver biopsies and abdominal MRI exams at baseline and end-of-treatment (72 weeks) were included (n = 76). Adipose tissue compartment volumes were obtained using MRI.

RESULTS

Treatment and placebo groups did not differ in baseline adipose tissue volumes, or in change in adipose tissue volumes longitudinally (p = 0.107 to 0.745). Deep subcutaneous adipose tissue (dSAT) and visceral adipose tissue volume reductions were associated with histologic improvement in NASH (i.e., NAS [non-alcoholic fatty liver disease activity score] reductions of ≥2 points, at least 1 point from lobular inflammation and hepatocellular ballooning, and no worsening of fibrosis) (p = 0.031, and 0.030, respectively). In a stepwise logistic regression procedure, which included demographics, treatment group, baseline histology, baseline and changes in adipose tissue volumes, MRI hepatic proton density fat fraction (PDFF), and serum aminotransferases as potential predictors, reductions in dSAT and PDFF were associated with histologic improvement in NASH (regression coefficient = -2.001 and -0.083, p = 0.044 and 0.033, respectively).

CONCLUSIONS

In adults with NASH in the FLINT trial, those with greater longitudinal reductions in dSAT and potentially visceral adipose tissue volumes showed greater hepatic histologic improvements, independent of reductions in hepatic PDFF.

CLINICAL TRIAL NUMBER

NCT01265498.

IMPACT AND IMPLICATIONS

Although central obesity has been identified as a risk factor for obesity-related disorders including insulin resistance and cardiovascular disease, the role of central obesity in non-alcoholic steatohepatitis (NASH) warrants further clarification. Our results highlight that a reduction in central obesity, specifically deep subcutaneous adipose tissue and visceral adipose tissue, may be related to histologic improvement in NASH. The findings from this analysis should increase awareness of the importance of lifestyle intervention in NASH for clinical researchers and clinicians. Future studies and clinical practice may design interventions that assess the reduction of deep subcutaneous adipose tissue and visceral adipose tissue as outcome measures, rather than simply weight reduction.

Non-alcoholic fatty liver disease: Definition and subtypes

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide, with a global prevalence of approximately 30%. However, the prevalence of NAFLD has been variously reported depending on the comorbidities. The rising prevalence of obesity in both the adult and pediatric populations is projected to consequently continue increasing NAFLD prevalence. It is a major cause of chronic liver disease worldwide, including cirrhosis and hepatocellular carcinoma (HCC). NAFLD has a variety of clinical phenotypes and heterogeneity due to the complexity of pathogenesis and clinical conditions of its occurrence, resulting in various clinical prognoses. In this article, we briefly described the basic definition of NAFLD and classified the subtypes based on current knowledge in this field.

Screening strategy for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, affecting approximately 25% of the general population worldwide, and is forecasted to increase global health burden in the 21st century. With the advancement of non-invasive tests for assessing and monitoring of steatosis and fibrosis, NAFLD screening is now feasible, and is increasingly highlighted in international guidelines related to hepatology, endocrinology, and pediatrics. Identifying high-risk populations (e.g., diabetes mellitus, obesity, metabolic syndrome) based on risk factors and metabolic characteristics for non-invasive screening is crucial and may aid in designing screening strategies to be more precise and effective. Many screening modalities are currently available, from serum-based methods to ultrasonography, transient elastography, and magnetic resonance imaging, although the diagnostic performance, cost, and accessibility of different methods may impact the actual implementation. A two-step assessment with serum-based fibrosis-4 index followed by imaging test vibration-controlled transient elastography can be an option to stratify the risk of liverrelated complications in NAFLD. There is a need for fibrosis surveillance, as well as investigating the cost-effectiveness of different screening algorithms and engaging primary care for first-stage triage screening.

Normalization of circulating plasma levels of miRNAs in HIV-1/HCV co-infected patients following direct-acting antiviral-induced sustained virologic response

In a previous recent work, we recognized three plasma circulating microRNAs (miRNAs)-miR-100-5p_iso3p:-2, miR-122-5p, and miR-192-5p-that correlate largely with liver fibrosis evolution in human immunodeficiency virus type 1 (HIV-1)/hepatitis C virus (HCV) co-infected patients. Here, we investigated whether levels of these three circulating miRNAs can be associated to liver disease evolution in HIV-1/HCV co-infected patients which have achieved HCV sustained virologic response (SVR) 12 weeks after finishing treatment. Eighty-one chronic HIV-1/HCV co-infected patients were longitudinally recruited at baseline (T0) of DAA therapy and 12 weeks (T12) after finishing therapy. At T0 most of the study patients displayed transient elastography values linked to an advanced stage of liver fibrosis (F0-1 9%, F2 11%, F3 32%, F4 48%). Significant reductions in the levels of circulating miR-100-5p_iso3p:-2, miR-122-5p, and miR-192-5p were detected at T12 in SVR patients, in the overall cohort (P < 0.0001, P < 0.0001, and P = 0.0008, respectively) and in patients with advanced (F3-4) liver fibrosis (p < 0.0001, p < 0.0001, and P = 0.0011, respectively). Of note, no significant reduction in the study miRNA levels was found at T12 in patients who did not achieve SVR (P = 0.8750, P = 0.1250, and P = 0.1260, respectively). HCV-cured patients, in contrast to non-responders, significantly reduced their liver stiffness after two years of achieving SVR (p < 0.0001). DAA-induced SVR is linked with a significant reduction in circulating levels of miR-100-5p_iso3p:-2, miR-122-5p, and miR-192-5p. Our results indicate that miRNA plasma levels may be a useful biomarker of liver damage progression in HIV-1/HCV co-infected individuals that reach DAA-induced SVR.

The I148M PNPLA3 variant mitigates niacin beneficial effects: How the genetic screening in non-alcoholic fatty liver disease patients gains value

Background

The PNPLA3 p.I148M impact on fat accumulation can be modulated by nutrients. Niacin (Vitamin B3) reduced triglycerides synthesis in in vitro and in vivo NAFLD models.

Objectives

In this study, we aimed to investigate the niacin-I148M polymorphism crosstalk in NAFLD patients and examine niacin's beneficial effect in reducing fat by exploiting hepatoma cells with different PNPLA3 genotype.

Design

We enrolled 172 (Discovery cohort) and 358 (Validation cohort) patients with non-invasive and histological diagnosis of NAFLD, respectively. Dietary niacin was collected from food diary, while its serum levels were quantified by ELISA. Hepatic expression of genes related to NAD metabolism was evaluated by RNAseq in bariatric NAFLD patients (n = 183; Transcriptomic cohort). Hep3B (148I/I) and HepG2 (148M/M) cells were silenced (siHep3B) or overexpressed (HepG2^I148+ ) for PNPLA3, respectively.

Results

In the Discovery cohort, dietary niacin was significantly reduced in patients with steatosis ≥ 2 and in I148M carriers. Serum niacin was lower in subjects carrying the G at risk allele and negatively correlated with obesity. The latter result was confirmed in the Validation cohort. At multivariate analysis, the I148M polymorphism was independently associated with serum niacin, supporting that it may be directly involved in the modulation of its availability. siHep3B cells showed an impaired NAD biosynthesis comparable to HepG2 cells which led to lower niacin efficacy in clearing fat, supporting a required functional protein to guarantee its effectiveness. Conversely, the restoration of PNPLA3 Wt protein in HepG2^I148+ cells recovered the NAD pathway and improved niacin efficacy. Finally, niacin inhibited de novo lipogenesis through the ERK1/2/AMPK/SIRT1 pathway, with the consequent SREBP1-driven PNPLA3 reduction only in Hep3B and HepG2^I148M+ cells.

Conclusions

We demonstrated a niacin-PNPLA3 I148M interaction in NAFLD patients which possibly pave the way to vitamin B3 supplementation in those with a predisposing genetic background.

Perspectives on the Underlying Etiology of HCC and Its Effects on Treatment Outcomes

Hepatocellular carcinoma (HCC) continues to be a serious medical problem with poor prognosis worldwide. The distribution of the major etiologies of HCC is changing due to the progress of anti-viral treatments, including hepatitis B virus (HBV) suppression by nucleoside/nucleotide analogues (NAs) and increased sustained virologic response (SVR) rates by direct-acting antivirals (DAAs) for hepatitis C virus (HCV), as well as the rising trend of nonviral liver disease. Although viral hepatitis remains the most common cause of HCC, non-alcoholic liver disease (NAFLD) with metabolic syndrome and alcohol-associated liver disease (ALD) are increasing. Effective and well-tolerated NAs treatment can slow the disease progression of chronic HBV infection to cirrhosis, end-stage liver disease, and reduce HCC risk. Treatment with NAs is also associated with significant improvement in the long-term survival of patients with HBV infection who already have HCC. DAAs have achieved viral elimination in almost all patients with HCV without significant adverse events, even in patients with decompensated liver cirrhosis and HCC. Similarly, DAA therapy can reduce disease progression, liver and non-liver complications, and improve the long-term survival of patients with chronic HCV infection with or without HCC. Meanwhile, NAFLD is a rapidly increasing cause of HCC along with the epidemics of obesity and type 2 diabetes globally. NAFLD-related HCC can occur in patients without cirrhosis and is known to have a lower survival rate than viral hepatitis-related HCC. Since there is currently no specific pharmacotherapy effective for NAFLD, lifestyle modification and prevention of complications are important to improve prognosis. Additionally, ALD is the second fastest-growing cause of HCC-related deaths, especially with an accelerated trend since the COVID-19 pandemic. This review provides an overview of the epidemiologic trends in the etiologies of HCC, and the progress of treatments for each etiology and the impact on outcome in the patients with HCC.

NAFLD as the metabolic hallmark of obesity

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide, associated with a high risk of progression to NASH, liver cirrhosis and hepatocarcinoma. Its prevalence is closely related to obesity (understood as adipose-based disease and insulin resistance), which makes that at present NAFLD can be considered a metabolic dysfunction hallmark, regardless of the body mass index. Despite being such a prevalent condition, with such severe consequences, at present there are no reliable biomarkers for its diagnosis or specific treatment. Significant and sustained weight loss, as well as some antidiabetic treatments, has shown promising results for NAFLD but data needs confirmation in larger clinical trials and longer follow-up. Efforts should be made for a better and more accurate baseline diagnosis (including large-scale genetics), identification of patients at higher risk for progression to NASH as well as adequate treatment, to allow us to offer a personalized approach in NAFLD in the context of precision medicine.

MAFLD: a multisystem disease

Nonalcoholic fatty liver disease (NAFLD), affecting about 25% of general population and more than 50% of dysmetabolic patients, is an emerging cause of chronic liver disease and its complications. Recently, an international consensus of experts proposed to rename this disease as 'Metabolic dysfunction-Associated Fatty Liver Disease' (MAFLD) to focus on the bidirectional interplay between fatty liver and metabolic alterations and to stress the need of assessing fatty liver independently from alcohol consumption and other coexisting causes of liver disease. The peculiarity of NAFLD/MAFLD lies in the presence of a higher risk of not only - as expected - liver-related events but also of extrahepatic events, mostly cardiovascular and cancers. Available evidence suggests that these associations are not only the expression of sharing the same risk factors but shed light about the ability of NAFLD/MAFLD and particularly of its progressive form - nonalcoholic/metabolic dysfunction-associated steatohepatitis - to act as an independent risk factor via promotion of atherogenic dyslipidemia and a proinflammatory, profibrogenic, and procoagulant systemic environment. The present review summarizes available epidemiological and clinical evidence supporting the concept of NAFLD/MAFLD as a multisystemic disease, and highlights potential explanatory mechanisms underlying the association between NAFLD/MAFLD and extrahepatic disorders.

Genetic Polymorphisms and Diversity in Nonalcoholic Fatty Liver Disease (NAFLD): A Mini Review

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease with a wide spectrum of liver conditions ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The prevalence of NAFLD varies across populations, and different ethnicities have specific risks for the disease. NAFLD is a multi-factorial disease where the genetics, metabolic, and environmental factors interplay and modulate the disease's development and progression. Several genetic polymorphisms have been identified and are associated with the disease risk. This mini-review discussed the NAFLD's genetic polymorphisms and focusing on the differences in the findings between the populations (diversity), including of those reports that did not show any significant association. The challenges of genetic diversity are also summarized. Understanding the genetic contribution of NAFLD will allow for better diagnosis and management explicitly tailored for the various populations.

Effect of common genetic variants on the risk of cirrhosis in non-alcoholic fatty liver disease during 20 years of follow-up

BACKGROUND AND AIMS

Several genotypes associate with a worse histopathological profile in patients with non-alcoholic fatty liver disease (NAFLD). Whether genotypes impact long-term outcomes is unclear. We investigated the importance of PNPLA3, TM6SF2, MBOAT7 and GCKR genotype for the development of severe outcomes in NAFLD.

METHOD

DNA samples were collected from 546 patients with NAFLD. Advanced fibrosis was diagnosed by liver biopsy or elastography. Non-alcoholic steatohepatitis (NASH) was histologically defined. Additionally, 5396 controls matched for age, sex and municipality were identified from population-based registers. Events of severe liver disease and all-cause mortality were collected from national registries. Hazard ratios (HRs) adjusted for age, sex, body mass index and type 2 diabetes were estimated with Cox regression.

RESULTS

In NAFLD, the G/G genotype of PNPLA3 was associated with a higher prevalence of NASH at baseline (odds ratio [OR] 3.67, 95% CI = 1.66-8.08), but not with advanced fibrosis (OR 1.81, 95% CI = 0.79-4.14). After up to 40 years of follow-up, the PNPLA3 G/G genotype was associated with a higher rate of severe liver disease (adjusted hazard ratio [aHR] 2.27, 95% CI = 1.15-4.47) compared with the C/C variant. NAFLD patients developed cirrhosis at a higher rate than controls (aHR 9.00, 95% CI = 6.85-11.83). The PNPLA3 G/G genotype accentuated this rate (aHR 23.32, 95% = CI 9.14-59.47). Overall mortality was not affected by any genetic variant.

CONCLUSION

The PNPLA3 G/G genotype is associated with an increased rate of cirrhosis in NAFLD. Our results suggest that assessment of the PNPLA3 genotype is of clinical relevance in patients with NAFLD to individualize monitoring and therapeutic strategies.