PNPLA3 gene polymorphism and response to lifestyle modification in patients with nonalcoholic fatty liver disease

Cell and gene therapeutic approaches in non-alcoholic fatty liver disease

Non-Alcoholic Fatty Liver Disease (NAFLD) refers to a range of conditions marked by the buildup of triglycerides in liver cells, accompanied by inflammation, which contributes to liver damage, clinical symptoms, and histopathological alterations. Multiple molecular pathways contribute to NAFLD pathogenesis, including immune dysregulation, endoplasmic reticulum stress, and tissue injury. Both the innate and adaptive immune systems play crucial roles in disease progression, with intricate crosstalk between liver and immune cells driving NAFLD development. Among emerging therapeutic strategies, cell and gene-based therapies have shown promise. This study reviews the pathophysiological mechanisms of NAFLD and explores the therapeutic potential of cell-based interventions, highlighting their immunomodulatory effects, inhibition of hepatic stellate cells, promotion of hepatocyte regeneration, and potential for hepatocyte differentiation. Additionally, we examine gene delivery vectors designed to target NAFLD, focusing on their role in engineering hepatocytes through gene addition or editing to enhance therapeutic efficacy.

Global Epidemiology and Implications of PNPLA3 I148M Variant in Metabolic Dysfunction-Associated Steatotic Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

PNPLA3 rs738409 variant is a risk factor for onset and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). We aimed to assess its global prevalence, clinical and histological characteristics, and long-term outcomes in patients with MASLD.

METHODS

PubMed and Embase databases were searched until December 30, 2023, for observational studies on PNPLA3 genotyped adults with MASLD. Proportions were pooled using a generalized linear mixed model with Clopper-Pearson intervals. Continuous and dichotomous variables were analyzed using the DerSimonian-Laird method. International Prospective Register of Systematic Reviews registration number: CRD42023449838.

RESULTS

A total of 109 studies involving 118,302 individuals with MASLD were identified. The overall minor allele frequency of the G allele [MAF(G)] at PNPLA3 was 0.45 (95% confidence interval [CI]: 0.43; 0.48) with high heterogeneity (I2 = 98%). The highest MAF(G) was found in Latin America (0.63) and the lowest in Europe (0.38). No African countries were identified. Carriers of the PNPLA3 variant had reduced adiposity, altered fat metabolism, and worse liver damage/histology than noncarriers. There was significant heterogeneity in the clinical/histological analyses (I2 > 50%). Only the PNPLA3 GG genotype was associated with higher mortality and liver-related events with no heterogeneity (I2 = 0%). Metaregressions showed the influence of adiposity, age, diabetes mellitus, and glucose on some PNPLA3 expression parameters. Overall, there was a moderate risk of bias in the included studies.

CONCLUSIONS

This study reveals the global pattern of PNPLA3 and its clinical, histological, and outcome implications in MASLD. Patients with MASLD and PNPLA3 variant have different clinical features and worse liver severity, and only PNPLA3 GG has a higher risk of mortality and liver outcomes. Our findings highlight the importance of PNPLA3 genotyping in clinical trials and advocate for personalized medicine approaches.

Nephrological, Pulmonary, and Dermatological Complications in the Context of MAFLD/NAFLD: A Narrative Review

Background: The most common cause of chronic liver disease is now known to be non-alcoholic fatty liver disease (NAFLD), recently redefined as metabolic-associated fatty liver disease (MAFLD). This review aims to synthesize current evidence on the pathophysiology and clinical implications of nephrological, pulmonary, and dermatological manifestations among NAFLD/MAFLD patients. In order to find safe and efficient treatments, NAFLD/MAFLD has emerged as a primary concern for hepatologists worldwide. Methods: We conducted a comprehensive review of the literature from major databases, focusing on studies that evaluated the extrahepatic manifestations of NAFLD/MAFLD. Emphasis was placed on identifying pathophysiological mechanisms and assessing their clinical impact on renal, pulmonary, and dermatological systems. Results: Recent developments in the management of chronic viral hepatitis have lowered the mortality rate associated with chronic liver disease. However, the prevalence of NAFLD/MAFLD continues to rise, making chronic liver disease a significant health concern for the future. An increasing percentage of patients on liver transplant waiting lists now have cirrhosis and hepatocellular carcinoma due to non-alcoholic liver disease. Furthermore, the incidence and prevalence of chronic kidney disease have surged, linking NAFLD/MAFLD to higher morbidity, mortality, and healthcare costs. Conclusions: NAFLD/MAFLD is underdiagnosed and underappreciated, yet its incidence is rapidly increasing, raising concerns about a potential global epidemic. Given its multisystemic impact-extending to renal, pulmonary, and dermatological complications-it is crucial to develop interdisciplinary strategies for early detection and effective management of the disease.

PNPLA3 rs738409, environmental factors and liver-related mortality in the US population

BACKGROUND & AIMS

Little is known about the interplay between patatin-like phospholipase domain-containing protein 3 (PNPLA3 rs738409 C>G), environmental factors, and the risk of liver-related death.

METHODS

A total of 4,361 adults were selected from NHANES III, 1991-1994. All participants were linked to the National Death Index until 2019 (mean follow-up: 23.2 years). Liver-related death was the study outcome. Associations of PNPLA3, diet, light alcohol intake, smoking, and BMI (kg/m2) with liver-related death were examined using competing risk regression models.

RESULTS

The PNPLA3 G-allele was significantly associated with liver-related death (adjusted subhazard ratio [adj.sHR] 2.9, 95% CI 1.4-5.8). Light alcohol intake (adj.sHR 2.2, 95% CI 1.1-4.5), top quartiles of monounsaturated fat (adj.sHR 0.43, 95% CI 0.12-0.99) and cholesterol (adj.sHR 2.6, 95% CI 1.00-8.8), coffee intake ≥3 cups/day (adj.sHR 0.05, 95% CI 0.06-0.10), former/current smoking (adj.sHR 1.8, 95% CI 1.2-2.6), BMI (adj.sHR 1.1, 95% CI 1.03-1.2), and healthy eating index (adj.sHR 0.96, 95% CI 0.93-0.98) were associated with liver-related death. Joint effects between PNPLA3 and environmental factors showed that the risk of liver-related death was significantly increased in carriers of the G-allele with light alcohol intake (adj.sHR 3.7), higher consumption (top quartile) of cholesterol (adj.sHR 4.1), former (adj.sHR 4.3) or current (adj.sHR 3.5) smoking, or BMI ≥30 (adj.sHR 4.0) kg/m2. The effects of the G-allele on the risk of LRD were significantly attenuated in those with top quartile consumption of monounsaturated fat (adj.sHR 0.5) or coffee intake ≥3 cups/day (adj.sHR 0.09). Healthy eating index was inversely associated with liver-related death across all PNPLA3 genotypes (adj.sHR 0.94, 0.96, and 0.97 for CC, CG, and GG, respectively).

CONCLUSIONS

PNPLA3 is associated with liver-related death and this relationship is significantly modified by anthropometric and environmental factors.

IMPACT AND IMPLICATIONS

Light alcohol intake, dietary factors (healthy eating index, monounsaturated fat, cholesterol), coffee intake, smoking status, and BMI are independently associated with the risk of liver-related death. The increased inherited risk of liver-related death associated with PNPLA3 rs738409 appears to be attenuated by healthy eating index, monounsaturated fat, and coffee intake, and exacerbated by light alcohol intake, smoking, and BMI. Reducing harmful environmental exposures and increasing healthy eating habits may help mitigate the risk of liver-specific mortality even in those with high genetic risk.

Impact of PNPLA3 in Lean Individuals and in Cryptogenic Steatotic Liver Disease

BACKGROUND

Although metabolic dysfunction-associated steatotic liver disease (MASLD) is strongly associated with obesity, around 20% of individuals with hepatic steatosis may nonetheless have normal body mass index, a condition often referred to as lean nonalcoholic fatty liver disease (NAFLD). Under the new nomenclature and definition of MASLD, lean NAFLD can be further divided into lean MASLD (when there is one or more cardiometabolic risk factors) and cryptogenic steatotic liver disease (when there is no cardiometabolic risk factor).

RESULTS

Current studies suggest that the at-risk PNPLA3 rs738409 variant is more common among individuals with lean NAFLD than their overweight and obese counterparts. However, even in this group, cardiometabolic risk factors are often required for the development of hepatic steatosis and liver injury. In the general population, PNPLA3 gene polymorphism is associated with an increased risk of MASLD, more severe liver histology (i.e., the presence of steatohepatitis and fibrosis) and future development of hepatocellular carcinoma and cirrhotic complications. Emerging data also suggest that individuals carrying the PNPLA3 GG genotype might have a greater reduction in hepatic steatosis and liver enzymes with lifestyle intervention and metabolic treatments, such as glucagon-like peptide-1 receptor agonists.

CONCLUSION

Studies have not specifically examined the impact of PNPLA3 in lean individuals.

Bromelain and liver health: A comprehensive systematic review of preclinical studies

BACKGROUND

Liver diseases pose a significant challenge to the well-being of the public, given their high prevalence and the potential to escalate to liver failure and hepatocellular carcinoma. The efficacy of current therapies is rather limited, resulting in the manifestation of severe side effects. Bromelain, derived from the pineapple plant, exhibits promising prospects for the treatment of inflammatory disorders, cancer, and wound healing, although its impact on liver functionality remains largely unexplored.

OBJECTIVE

To evaluate the efficiency of bromelain in liver injuries, we performed a systematic review of preclinical studies.

METHOD

Our search was conducted in August 2020 on PubMed and Scopus, employing the search terms "Liver disease," "Liver injury," and "Bromelain," with subsequent updates in December 2023.

RESULTS

Out of the 329 articles that were examined, only 7 fulfilled the criteria for inclusion.

CONCLUSION

Our research suggests that bromelain possesses both prophylactic and curative qualities in terms of liver damage, as supported by its ability to decrease enzyme levels, enhance liver structure, reduce oxidative stress markers, and regulate lipid metabolism. In summary, bromelain demonstrates a capacity to enhance liver function across a range of injury types.

Genetic Risk Factors for Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), is the most common cause of liver disease, and its burden on health systems worldwide continues to rise at an alarming rate. MASLD is a complex disease in which the interactions between susceptible genes and the environment influence the disease phenotype and severity. Advances in human genetics over the past few decades have provided new opportunities to improve our understanding of the multiple pathways involved in the pathogenesis of MASLD. Notably, the PNPLA3, TM6SF2, GCKR, MBOAT7 and HSD17B13 single nucleotide polymorphisms have been demonstrated to be robustly associated with MASLD development and disease progression. These genetic variants play crucial roles in lipid droplet remodeling, secretion of hepatic very low-density lipoprotein and lipogenesis, and understanding the biology has brought new insights to this field. This review discusses the current body of knowledge regarding these genetic drivers and how they can lead to development of MASLD, the complex interplay with metabolic factors such as obesity, and how this information has translated clinically into the development of risk prediction models and possible treatment targets.

Long-term Favorable Efficacy of Regular and Repeated Hospitalizations with a Personalized Diet and Exercise Treatment for Steatotic Liver Disease

Objective The long-term impact of personalized diet and exercise programs for steatotic liver disease (SLD) remains unclear. Materials The subjects of this retrospective cohort study included 104 consecutive Japanese patients with SLD. The long-term treatment efficacy of personalized diet and exercise treatment was evaluated two years after the start of observation. Regular and repeated hospitalizations every 6 months (RRH group, n=23) indicated the 4 times of the number of hospitalizations, and irregular hospitalizations (IH group, n=56) showed the 1 to three times. The group without hospitalization was defined as the no hospitalization group (NH group, n=25). To balance confounding biases, the difference in treatment efficacy between the RRH and IH groups was evaluated using propensity score (PS)-matched analysis. A diet of 25 to 30 kcal/kg multiplied by ideal body weight (BW) daily, and aerobic and resistance exercise (exercise intensity of 4 to 5 metabolic equivalents daily, respectively) was performed for 6 days. Results At 2 years compared to baseline, the decrease rates of liver function tests, HbA1c, and physical findings in the RRH group were significantly higher than those in the NH or IH groups by multiple comparisons. According to the liver function tests and physical findings, the rate of decrease in the RRH group (17 cases) was significantly higher than that in the IH group (17 cases) using a PS-matched analysis. Conclusion The present study indicated the long-term favorable efficacy of personalized diet and exercise programs for SLD. In particular, this RRH program was effective in improving the findings of liver function tests and might help to sustain diet and exercise.

Genetics of Metabolic Dysfunction-associated Steatotic Liver Disease: The State of the 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 insight into the updated pharmacotherapy of metabolic-associated fatty liver disease (MAFLD) or metabolic dysfunction-associated steatohepatitis (MASH) in lean individuals: a review

Metabolic-associated fatty liver disease (MAFLD) or metabolic dysfunction-associated steatohepatitis (MASH) in lean individuals represents a distinctive subset of MASH. Current pharmacotherapies, for MASH as demonstrated in clinical trials, predominantly target obese patients with limited consideration for lean MASH. We aimed to systematically review the literature on the pharmacotherapy of lean MASH. We searched standard medical databases, such as PubMed, Embase, Scopus, Cochrane CENTRAL, and ClinicalTrials.gov to identify eligible studies published in English up to 31 December 2023 regarding the effect of pharmacological interventions in individuals with lean MASH. We have summarized the role of various drug classes including peroxisome proliferator-activated receptor agonists, glucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter 2 inhibitors, vitamin E, farnesoid X receptor agonists, selective thyroid hormone receptor-β agonists, and selective cholesterol absorption inhibitors. Consequently, lifestyle interventions, encompassing dietary modifications, exercise, and weight loss particularly directed at visceral obesity or achieving a reduction in body weight are recommended for all non-obese individuals with MASH. A highlight on the only available treatment recommendation for lean MASH is also presented. The available evidence regarding the efficacy of various drugs for the treatment of lean MASH is limited. Conclusive evidence is warranted from clinical trials exclusively involving lean individuals with MASH.

Lifestyle intervention for metabolic dysfunction-associated fatty liver disease: a 24-h integrated behavior perspective

INTRODUCTION

The prevalence, health and socioeconomic burden of metabolic dysfunction-associated fatty liver disease (MAFLD) is growing, increasing the need for novel evidence-based lifestyle approaches. Lifestyle is the cornerstone for MAFLD management and co-existing cardiometabolic dysfunction. The aim of this review was to evaluate the evidence for lifestyle management of MAFLD, with a specific lens on 24-hour integrated behaviour and provide practical recommendations for implementation of the evidence.

RESULTS

Weight loss ≥ 7-10% is central to lifestyle management; however, liver and cardiometabolic benefits are attainable with improved diet quality and exercise even without weight loss. Lifestyle intervention for MAFLD should consider an integrated '24-h' approach that is cognisant of diet, physical activity/exercise, sedentary behavior, smoking, alcohol intake and sleep. Dietary management emphasises energy deficit and improved diet quality, especially the Mediterranean diet, although sociocultural adaptations to meet preferences should be considered. Increasing physical activity and reducing sedentary behavior can prevent MAFLD, with strongest evidence in MAFLD supporting regular structured moderate-vigorous aerobic exercise for 150-240 min/week. Resistance training in addition to aerobic exercise should be considered and prioritised for those who are losing body mass via diet and/or pharmacological approaches and those with sarcopenia, to minimise bone and lean mass loss. Limited evidence suggests that sleep is important for MAFLD prevention. Emerging novel approaches to diet and exercise may address some of the key barriers to behaviour change (e.g. lack of time, access to resources and social support).

FUTURE DIRECTIONS

Large-scale multidisciplinary trials in people with MAFLD with long-term follow-up, that can be scaled up into mainstream healthcare, are required. Future management guidelines should consider the heterogeneity of MAFLD and specialised models of care that coordinate the health workforce to manage the increased and growing MAFLD population.

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

BACKGROUND AND AIM

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

METHOD

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

RESULTS

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

CONCLUSION

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

Are we ready for genetic testing in metabolic dysfunction-associated steatotic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD), with its steadily increasing prevalence, represents now a major problem in public health. A proper referral could benefit from tools allowing more precise risk stratification. To this end, in recent decades, several genetic variants that may help predict and refine the risk of development and progression of MASLD have been investigated. In this review, we aim to discuss the role genetics in MASLD plays in everyday clinical practice. We performed a comprehensive literature search of PubMed for relevant publications. Available evidence highlights the emergence of genetic-based noninvasive algorithms for diagnosing fatty liver, metabolic dysfunction-associated steatohepatitis, fibrosis progression and occurrence of liver-related outcomes including hepatocellular carcinoma. Nevertheless, their accuracy is not optimal and application in everyday clinical practice remains challenging. Furthermore, susceptible genetic markers have recently become subjects of great scientific interest as therapeutic targets in precision medicine. In conclusion, decisional algorithms based on genetic testing in MASLD to facilitate the clinician decisions on management and treatment are under growing investigation and could benefit from artificial intelligence methodology.

Dietary inflammatory impact on NAFLD development in obese vs. lean individuals: an analysis based on NHANES 2003-2018

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), often linked with obesity, can also affect individuals with normal weight, a condition known as "lean NAFLD", imposing comparable burdens and adverse effects. However, the impact of diet on lean NAFLD remains underexplored. The objective of this study is to investigate the correlation between the Dietary Inflammatory Index (DII) and NAFLD among Americans, stratified by waist-to-height ratio (WHtR) and body mass index (BMI).

METHODS

Five thousand one hundred fifty-two participants from the National Health and Nutrition Examination Survey (NHANES) 2003-2018 were comprised in the final analysis. NAFLD and advanced liver fibrosis were diagnosed by serological markers. Lean and abdominal lean individuals were identified using BMI and WHtR, separately. DII was determined by assigning scores to 28 distinct food parameters based on their inflammatory potential, obtained from the NAHNES website. Differences across DII quartiles were evaluated using the Kruskal-Wallis H Test, Chi-Square Test along with One-Way ANOVA. The correlation between DII and NAFLD was determined by multiple regression models and subgroup analyses.

RESULTS

Among the 5152 subjects, 2503 were diagnosed with NAFLD, including 86 cases of lean NAFLD and 8 cases of abdominal lean NAFLD. DII was positively linked with NAFLD (Odds Ratio (OR) = 1.81 [1.48-2.21], P < 0.001) and advanced liver fibrosis (OR = 1.46 [1.02-2.07], P = 0.037). Further analysis revealed that this association was primarily observed in obese or abdominal obese participants (In BMI ≥ 25.00 kg/m^2, OR = 1.56 [1.23-1.98], P < 0.001. In WHtR> 0.50, OR = 1.48 [1.23-1.79], P < 0.001.), rather than their lean counterparts. Subgroup analyses indicated that female individuals, without a diagnosis of hypertension or diabetes appeared to be more sensitive to the rise in DII.

CONCLUSIONS

Our data demonstrated a significant positive correlation between DII and NAFLD in the general population. However, the impact of a pro-inflammatory diet was less prominent in lean individuals compared to obese ones.

Genetics of liver disease in adults

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

Exploring the role of genetic variations in NAFLD: implications for disease pathogenesis and precision medicine approaches

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver diseases, affecting more than one-quarter of people worldwide. Hepatic steatosis can progress to more severe forms of NAFLD, including NASH and cirrhosis. It also may develop secondary diseases such as diabetes and cardiovascular disease. Genetic and environmental factors regulate NAFLD incidence and progression, making it a complex disease. The contribution of various environmental risk factors, such as type 2 diabetes, obesity, hyperlipidemia, diet, and sedentary lifestyle, to the exacerbation of liver injury is highly understood. Nevertheless, the underlying mechanisms of genetic variations in the NAFLD occurrence or its deterioration still need to be clarified. Hence, understanding the genetic susceptibility to NAFLD is essential for controlling the course of the disease. The current review discusses genetics' role in the pathological pathways of NAFLD, including lipid and glucose metabolism, insulin resistance, cellular stresses, and immune responses. Additionally, it explains the role of the genetic components in the induction and progression of NAFLD in lean individuals. Finally, it highlights the utility of genetic knowledge in precision medicine for the early diagnosis and treatment of NAFLD patients.

Impact of genetic polymorphism on personalized diet and exercise program for steatotic liver disease

AIMS

The effects of genetic polymorphism on a personalized diet and exercise program for steatotic liver disease (SLD) are still unclear.

METHODS

Participants of this retrospective cohort study were 203 Japanese patients with SLD diagnosed by abdominal ultrasonography. All of them were introduced the personalized diet and exercise treatment. A diet of 25-30 kcal/kg multiplied by ideal body weight (BW) daily and aerobic and resistance exercise (exercise intensity of 4-5 metabolic equivalents daily, respectively) were performed for 6 days. Treatment efficacy was evaluated in terms of the rate of decrease of liver function tests, glycolipid metabolism markers, physical findings, image findings, and cardiovascular disease (CVD) risk score at 6 months compared with baseline. Furthermore, the impact of genetic polymorphism was also investigated.

RESULTS

At 6 months compared with baseline, liver function tests (AST, ALT, γGTP), glycolipid metabolism markers (hemoglobin A1c, triglycerides [TG], low-density lipoprotein cholesterol), physical findings (BW, body mass index), image finding (liver stiffness measurement), and CVD risk score (Suita score) improved significantly. There was no significant difference in treatment efficacy, except for the rates of decrease of TG, according to genotype PNPLA3 rs738409, TM6SF2 rs58542926, and HSD17B13 rs6834314. The rates of decrease of TG with TM6SF2 CT were significantly higher than those with CC or TT, and the rates of TG with HSD17B13 AA were significantly higher than those with AG by multiple comparisons.

CONCLUSION

Personalized diet and exercise program for SLD improved liver function tests, physical findings, glycolipid metabolism markers, and CVD risk score. Genetic polymorphism might partially affect treatment efficacy. Further studies should be performed to develop an individualized program for SLD, considering genetic polymorphism.

Lifestyle interventions in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a dynamic chronic liver disease that develops in close association with metabolic irregularities. Between 2016 and 2019, the global prevalence among adults was reported as 38% and among children and adolescents it was about 10%. NAFLD can be progressive and is associated with increased mortality from cardiovascular disease, extrahepatic cancers and liver complications. Despite these numerous adverse outcomes, no pharmacological treatments currently exist to treat nonalcoholic steatohepatitis, the progressive form of NAFLD. Therefore, the main treatment is the pursuit of a healthy lifestyle for both children and adults, which includes a diet rich in fruits, nuts, seeds, whole grains, fish and chicken and avoiding overconsumption of ultra-processed food, red meat, sugar-sweetened beverages and foods cooked at high heat. Physical activity at a level where one can talk but not sing is also recommended, including leisure-time activities and structured exercise. Avoidance of smoking and alcohol is also recommended. Policy-makers, community and school leaders need to work together to make their environments healthy by developing walkable and safe spaces with food stores stocked with culturally appropriate and healthy food items at affordable prices as well as providing age-appropriate and safe play areas in both schools and neighbourhoods.

The Impact and Burden of Dietary Sugars on the Liver

NAFLD, or metabolic dysfunction-associated steatotic liver disease, has increased in prevalence hand in hand with the rise in obesity and increased free sugars in the food supply. The causes of NAFLD are genetic in origin combined with environmental drivers of the disease phenotype. Dietary intake of added sugars has been shown to have a major role in the phenotypic onset and progression of the disease. Simple sugars are key drivers of steatosis, likely through fueling de novo lipogenesis, the conversion of excess carbohydrates into fatty acids, but also appear to upregulate lipogenic metabolism and trigger hyperinsulinemia, another driver. NAFLD carries a clinical burden as it is associated with obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease. Patient quality of life is also impacted, and there is an enormous economic burden due to healthcare use, which is likely to increase in the coming years. This review aims to discuss the role of dietary sugar in NAFLD pathogenesis, the health and economic burden, and the promising potential of sugar reduction to improve health outcomes for patients with this chronic liver disease.

Towards precision medicine in non-alcoholic fatty liver disease

Non-Alcoholic Fatty Liver Disease (NAFLD) refers to the accumulation of lipid laden vacuoles in hepatocytes, occurring in the context of visceral adiposity, insulin resistance and other features of the metabolic syndrome. Its more severe form (NASH, Non-Alcoholic Steatohepatitis) is becoming the leading aetiology of end-stage liver disease and hepatocellular carcinoma, and also contributes to cardiovascular disease, diabetes and extrahepatic malignancy. Management is currently limited to lifestyle modification and optimisation of the metabolic co-morbidities, with some of the drugs used for the latter also having shown some benefit for the liver. Licensed treatment modalities are currently lacking. A particular difficulty is the notorious heterogeneity of the patient population, which is poorly understood. A spectrum of disease severity associates in a non-linear way with a spectrum of severity of underlying metabolic factors. Heterogeneity of the liver in terms of mechanisms to cope with the metabolic and inflammatory stress and in terms of repair mechanisms, and a lack of knowledge hereof, further complicate the understanding of inter-individual variability. Genetic factors act as disease modifiers and potentially allow for some risk stratification, but also only explain a minor fraction of disease heterogeneity. Response to treatment shows a large variation in treatment response, again with little understanding of what is driving the absence of response in individual patients. Management can be tailored to patient's preferences in terms of diet modification, but tailoring treatment to knowledge on disease driving mechanisms in an individual patient is still in its infancy. Recent progress in analysing liver tissue as well as non-invasive tests hold, however, promise to rapidly improve our understanding of disease heterogeneity in NAFLD and provide individualised management.

PNPLA3 I148M and response to treatment for hepatic steatosis: A systematic review

BACKGROUND

It is unclear whether the patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 C-to-G single nucleotide polymorphism, resulting in the substitution of isoleucine to methionine at position 148 (I148M), impedes regression of hepatic steatosis when treating non-alcoholic fatty liver disease (NAFLD).

OBJECTIVES

Investigate if carriage of the PNPLA3 148M allele affects the anti-steatotic efficacy of all possible anti-NAFLD interventions, identify gaps in current knowledge and provide guidance for individual treatment.

METHODS

Research available in public databases was searched up to 13 November 2022. Studies were included if a treatment in NAFLD patients decreased hepatic steatosis in the pooled patient group or a PNPLA3 I148M polymorphism subgroup (II/IM/MM). The risk of bias was assessed using the Cochrane Risk-Of-Bias 2 Tool and the Newcastle-Ottawa Scale.

RESULTS

Moderate evidence indicates that NAFLD patients homozygous for the PNPLA3 148M allele benefit less or not at all from omega-3 carboxylic acids to decrease liver fat, while the PNPLA3 148I allele shows moderate benefit. Low evidence suggests that interventions employing lifestyle changes are more effective to reduce liver fat in NAFLD patients homozygous for the PNPLA3 148M allele compared to patients with wild-type PNPLA3.

CONCLUSIONS

NAFLD patients homozygous for the PNPLA3 148M allele might not benefit from omega-3 carboxylic acids to reduce hepatic steatosis in contrast to patients with wild-type PNPLA3. Instead, patients with two PNPLA3 148M alleles should be especially advised to adopt lifestyle changes. Genotyping for PNPLA3 I148M should be encouraged in therapeutic studies for NAFLD.

REGISTRATION NUMBER (PROSPERO)

CRD42022375028.

Nonalcoholic Fatty Liver Disease in Lean/Nonobese and Obese Individuals: A Comprehensive Review on Prevalence, Pathogenesis, Clinical Outcomes, and Treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, with an estimated prevalence of 25% globally. NAFLD is closely associated with metabolic syndrome, which are both becoming increasingly more common with increasing rates of insulin resistance, dyslipidemia, and hypertension. Although NAFLD is strongly associated with obesity, lean or nonobese NAFLD is a relatively new phenotype and occurs in patients without increased waist circumference and with or without visceral fat. Currently, there is limited literature comparing and illustrating the differences between lean/nonobese and obese NAFLD patients with regard to risk factors, pathophysiology, and clinical outcomes. In this review, we aim to define and further delineate different phenotypes of NAFLD and present a comprehensive review on the prevalence, incidence, risk factors, genetic predisposition, and pathophysiology. Furthermore, we discuss and compare the clinical outcomes, such as insulin resistance, dyslipidemia, hypertension, coronary artery disease, mortality, and progression to nonalcoholic steatohepatitis, among lean/nonobese and obese NAFLD patients. Finally, we summarize the most up to date current management of NAFLD, including lifestyle interventions, pharmacologic therapies, and surgical options.

Long-Term Effect of PNPLA3 on the Aggravation of Nonalcoholic Fatty Liver Disease in a Biopsy-Proven Cohort

The PNPLA3 rs738409 G allele increases the risk of not only nonalcoholic fatty liver disease (NAFLD) but also nonalcoholic steatohepatitis (NASH) or fibrosis.¹ It also affects the prognosis of patients with NAFLD in specific conditions. After liver transplantation, patients with NAFLD carrying the rs738409 GG genotype have a higher risk of graft steatosis² or development of hepatocellular carcinoma.³ In addition, rs738409 modifies the effects of medical intervention: patients with NAFLD carrying the GG genotype showed a lower effect of omega-3 polyunsaturated fatty acid treatment on the reduction of liver fat;⁴ in contrast, they were more sensitive to the beneficial effects of lifestyle modifications.^5,6.

Eating, diet, and nutrition for the treatment of non-alcoholic fatty liver disease

Nutrition and dietary interventions are a central component in the pathophysiology, but also a cornerstone in the management of patients with non-alcoholic fatty liver disease (NAFLD). Summarizing our rapidly advancing understanding of how our diet influences our metabolism and focusing on specific effects on the liver, we provide a comprehensive overview of dietary concepts to counteract the increasing burden of NAFLD. Specifically, we emphasize the importance of dietary calorie restriction independently of the macronutrient composition together with adherence to a Mediterranean diet low in added fructose and processed meat that seems to exert favorable effects beyond calorie restriction. Also, we discuss intermittent fasting as a type of diet specifically tailored to decrease liver fat content and increase ketogenesis, awaiting future study results in NAFLD. Finally, personalized dietary recommendations could be powerful tools to increase the effectiveness of dietary interventions in patients with NAFLD considering the genetic background and the microbiome, among others.

MTARC1 and HSD17B13 Variants Have Protective Effects on Non-Alcoholic Fatty Liver Disease in Patients Undergoing Bariatric Surgery

The severity of hepatic steatosis is modulated by genetic variants, such as patatin-like phospholipase domain containing 3 (PNPLA3) rs738409, transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) rs641738. Recently, mitochondrial amidoxime reducing component 1 (MTARC1) rs2642438 and hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13) rs72613567 polymorphisms were shown to have protective effects on liver diseases. Here, we evaluate these variants in patients undergoing bariatric surgery. A total of 165 patients who underwent laparoscopic sleeve gastrectomy and intraoperative liver biopsies and 314 controls were prospectively recruited. Genotyping was performed using TaqMan assays. Overall, 70.3% of operated patients presented with hepatic steatosis. NASH (non-alcoholic steatohepatitis) was detected in 28.5% of patients; none had cirrhosis. The increment of liver fibrosis stage was associated with decreasing frequency of the MTARC1 minor allele (p = 0.03). In multivariate analysis MTARC1 was an independent protective factor against fibrosis ≥ 1b (OR = 0.52, p = 0.03) and ≥ 1c (OR = 0.51, p = 0.04). The PNPLA3 risk allele was associated with increased hepatic steatosis, fibrosis, and NASH (OR = 2.22, p = 0.04). The HSD17B13 polymorphism was protective against liver injury as reflected by lower AST (p = 0.04) and ALT (p = 0.03) activities. The TM6SF2 polymorphism was associated with increased ALT (p = 0.04). In conclusion, hepatic steatosis is common among patients scheduled for bariatric surgery, but the MTARC1 and HSD17B13 polymorphisms lower liver injury in these individuals.

Current insights in molecular characterization of non-alcoholic fatty liver disease and treatment

There is a continuously rising incidence of non-alcoholic fatty liver disease (NAFLD) around the world, which parallels the increasing incidence of metabolic diseases. NAFLD is a range of liver conditions that contains simple non-alcoholic fatty liver and advanced non-alcoholic steatohepatitis. In serious cases, NAFLD may develop into cirrhosis or even liver cancer. NAFLD has an intense relationship with metabolic syndrome, type 2 diabetes mellitus. It is known that gut microbiota, and functional molecules such as adenosine monophosphate-activated protein kinase JNK, and peroxisome proliferator-activated receptors (PPARs) in progressing and treating NAFLD. Traditionally, the conventional and effective therapeutic strategy is lifestyle intervention. Nowadays, new medicines targeting specific molecules, such as farnesoid X receptor, PPARs, and GLP-1 receptor, have been discovered and shown beneficial effects on patients with NAFLD. In this article, we focus on the molecular mechanisms and therapeutic approaches to NAFLD.

Multiomics study of nonalcoholic fatty liver disease

Nonalcoholic fatty liver (NAFL) and its sequelae are growing health problems. We performed a genome-wide association study of NAFL, cirrhosis and hepatocellular carcinoma, and integrated the findings with expression and proteomic data. For NAFL, we utilized 9,491 clinical cases and proton density fat fraction extracted from 36,116 liver magnetic resonance images. We identified 18 sequence variants associated with NAFL and 4 with cirrhosis, and found rare, protective, predicted loss-of-function variants in MTARC1 and GPAM, underscoring them as potential drug targets. We leveraged messenger RNA expression, splicing and predicted coding effects to identify 16 putative causal genes, of which many are implicated in lipid metabolism. We analyzed levels of 4,907 plasma proteins in 35,559 Icelanders and 1,459 proteins in 47,151 UK Biobank participants, identifying multiple proteins involved in disease pathogenesis. We show that proteomics can discriminate between NAFL and cirrhosis. The present study provides insights into the development of noninvasive evaluation of NAFL and new therapeutic options.

Low skeletal muscle mass is associated with more severe histological features of non-alcoholic fatty liver disease in male

BACKGROUND/PURPOSE OF THE STUDY

Although low skeletal muscle mass is associated with non-alcoholic fatty liver disease (NAFLD), it is currently uncertain whether there are associations between weight-adjusted appendicular skeletal muscle (ASM%), severity of histological features of NAFLD, and the patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism. Our aim was to test for a possible influence of the PNPLA3 rs738409 variant on the association between ASM% and severity of NAFLD histological features.

METHODS

We enrolled 401 Chinese male with biopsy-proven NAFLD. Using a bioelectrical-impedance body composition analyzer (BIA, Inbody 720, Japan Inc., Tokyo), we calculated the ASM% as the percentage of total appendicular skeletal muscle mass (ASM, kg)/total body mass (kg) × 100.

RESULTS

Compared to those with high ASM%, patients with low ASM% (≤ 30.6, i.e., the median value of distribution of the whole sample) had a greater severity of individual histological features of NAFLD. These patients also had a higher risk of severe steatosis and non-alcoholic steatohepatitis (NASH) (adjusted-odds ratio [OR] 2.34, 95% CI 1.39-3.93, and adjusted-OR 2.22, 95% CI 1.30-3.77) even after adjusting for age, body mass index, diabetes, and serum creatinine levels. Carriage of the G allele of PNPLA3 rs738409 plus low ASM% was associated with a higher risk of severe steatosis and presence of liver fibrosis (OR 3.02, 95% CI 1.46-6.26, p = 0.003 and OR 2.18, 95% CI 1.03-4.60, p = 0.041 respectively), and there was a non-significant but borderline increased risk of NASH (OR 2.00, 95% CI 0.98-4.06, p = 0.056).

CONCLUSIONS

Low ASM% and the presence of a G allele within PNPLA3 rs738409 is associated with more severe histological features of NAFLD.

The genetic interactions between non-alcoholic fatty liver disease and cardiovascular diseases

The ongoing debate on whether non-alcoholic fatty liver disease (NAFLD) is an active contributor or an innocent bystander in the development of cardiovascular disease (CVD) has sparked interests in understanding the common mediators between the two biologically distinct entities. This comprehensive review identifies and curates genetic studies of NAFLD overlapping with CVD, and describes the colinear as well as opposing correlations between genetic associations for the two diseases. Here, CVD described in relation to NAFLD are coronary artery disease, cardiomyopathy and atrial fibrillation. Unique findings of this review included certain NAFLD susceptibility genes that possessed cardioprotective properties. Moreover, the complex interactions of genetic and environmental risk factors shed light on the disparity in genetic influence on NAFLD and its incident CVD. This serves to unravel NAFLD-mediated pathways in order to reduce CVD events, and helps identify targeted treatment strategies, develop polygenic risk scores to improve risk prediction and personalise disease prevention.

One size does not fit all; practical, personal tailoring of the diet to NAFLD patients

Different dietary regimens for weight loss have developed over the years. Since the most evidenced treatment for non-alcoholic fatty liver disease (NAFLD) is weight reduction, it is not surprising that more diets targeting obesity are also utilized for NAFLD treatment. However, beyond the desired weight loss effects, one should not ignore the dietary composition of each diet, which may not necessarily be healthy or safe over the long term for hepatic and extrahepatic outcomes, especially cardiometabolic outcomes. Some of these diets are rich in saturated fat and red meat, are very strict, and require close medical supervision. Some may also be very difficult to adhere to for long periods, thus reducing the patient's motivation. The evidence for a direct benefit to NAFLD by restrictive diets such as very-low-carb, ketogenic, very-low-calorie diets, and intermittent fasting is scarce, and the long-term safety has not been tested. Nowadays, the approach is that the diet should be tailored to the patient's cultural and personal preferences. There is strong evidence for the independent protective association of NAFLD with a diet based on healthy eating patterns of minimally-processed foods, low in sugar and saturated fat, high in polyphenols, and healthy types of fats. This leads to the conclusion that a Mediterranean diet should serve as a basis that can be restructured into other kinds of diets. This review will elaborate on the different diets and their role in NAFLD. It will provide a practical guide to tailor the diet to the patients without compromising its composition and safety.

Lifestyle Interventions for Non-Obese Patients Both with, and at Risk, of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease occurring in non-obese subjects (the so-called non-obese NAFLD) is a highly prevalent but neglected liver condition, which is closely associated with metabolic disorders and suboptimal lifestyles. Landmark studies have shown that lifestyle interventions are potentially beneficial in decreasing the risk of developing non-obese NAFLD and in ameliorating NAFLD in non-obese individuals with pre-existing NAFLD. Lifestyle interventions usually refer to changes in eating habits and physical activity, both of which have a powerful effect on non-obese NAFLD and on risk factors for non-obese NAFLD. However, to date, patients and health-care professionals have a poor awareness and understanding of non-obese NAFLD and the beneficial effects of lifestyle interventions in this patient population. The aim of this narrative review is to briefly discuss the evidence for the effects of lifestyle changes and what changes are needed amongst medical personnel and other stakeholders in order to raise awareness of non-obese NAFLD.

The Interplay Between Nonalcoholic Fatty Liver Disease and Kidney Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, involving approximately 25% of the general population and increasing in prevalence in patient populations afflicted with metabolic syndrome and type 2 diabetes. This article discusses the complex interplay between NAFLD and chronic kidney disease (CKD), as well as the underlying pathogenesis and mechanisms through which NAFLD and CKD are linked. Exploration of these sophisticated relationships and causative factors is essential to accurately assessing kidney function in patients with NAFLD, recommending pharmacologic treatment of disease, and identifying favorable avenues for future investigation.

Effect of Aerobic Exercise Alone or in Conjunction With Diet on Liver Function, Insulin Resistance and Lipids in Non-Alcoholic Fatty Liver Disease

BACKGROUND

Physical exercises are the first step of therapy for people with non-alcoholic fatty liver disease (NAFLD).

OBJECTIVE

The purpose of this meta-analysis is to evaluate the efficacy of aerobic exercise training with or without diet to ameliorate liver function, insulin resistance, and lipids in adults.

DATA SOURCES

We searched relevant databases up to 10 June 2021 for conducting a systematic review and meta-analysis of controlled trials lasting 4 or more weeks that investigated the effects of aerobic exercise alone or accompanied by diet on change in liver enzymes, intrahepatic fat (IHF), insulin resistance, and lipids.

RESULTS

Sixteen studies including 2255 participants were included. There was a significant pooled weighted mean differences (MD) for the comparison between aerobic exercise versus control in alanine aminotransferase (ALT; p = 0.003), aspartate aminotransferase (AST; p = 0.006), IHF (p = 0.0004), body mass (p = 0.0003), and body mass index (p = 0.004). Moreover, there was a significant pooled MD for the comparison between aerobic exercise plus diet versus control in ALT (p < 0.0001), AST (p = 0.01), IHF (p = 0.02), GGT (p < 0.00001), insulin (p < 0.0001), HOMA-IR (p < 0.00001), body mass (p < 0.0001), and BMI (p = 0.01).

CONCLUSION

Our findings demonstrate a role for aerobic exercise with and without diet protocol as a therapeutic purpose, and suggest that evaluation of aerobic training levels and aerobic training prescription plus diet should be routine in NAFLD.

Interaction between Lifestyle Changes and PNPLA3 Genotype in NAFLD Patients during the COVID-19 Lockdown

The coronavirus disease 2019 (COVID-19) lockdown dramatically changed people’s lifestyles. Diet, physical activity, and the PNPLA3 gene are known risk factors for non-alcoholic fatty liver disease (NAFLD). Aim: To evaluate changes in metabolic and hepatic disease in NAFLD patients after the COVID-19 lockdown. Three hundred and fifty seven NAFLD patients were enrolled, all previously instructed to follow a Mediterranean diet (MD). Anthropometric, metabolic, and laboratory data were collected before the COVID-19 lockdown in Italy and 6 months apart, along with ultrasound (US) steatosis grading and information about adherence to MD and physical activity (PA). In 188 patients, PNPLA3 genotyping was performed. After the lockdown, 48% of patients gained weight, while 16% had a worsened steatosis grade. Weight gain was associated with poor adherence to MD (p = 0.005), reduced PA (p = 0.03), and increased prevalence of PNPLA3 GG (p = 0.04). At multivariate analysis (corrected for age, sex, MD, PA, and PNPLA3 GG), only PNPLA3 remained independently associated with weight gain (p = 0.04), which was also associated with worsened glycemia (p = 0.002) and transaminases (p = 0.02). During lockdown, due to a dramatic change in lifestyles, half of our cohort of NAFLD patients gained weight, with a worsening of metabolic and hepatologic features. Interestingly, the PNPLA3 GG genotype nullified the effect of lifestyle and emerged as an independent risk factor for weight gain, opening new perspectives in NAFLD patient care.

Healthy dietary patterns and metabolic dysfunction-associated fatty liver disease in less-developed ethnic minority regions: a large cross-sectional study

BACKGROUND

Little is known about the associations between healthy dietary patterns and metabolic dysfunction-associated fatty liver disease (MAFLD) in less-developed ethnic minority regions (LEMRs), where the prevalence of MAFLD is increasing rapidly and dietary habits are quite different from those in developed countries. Moreover, a significant subset of MAFLD individuals in LEMRs are nonobese, but the efficacy of dietary patterns on MAFLD individuals with different obese statuses is also unclear. We aimed to test the associations of two wildly recommended a priori dietary patterns-Alternate Mediterranean diet (AMED) and Dietary Approaches to Stop Hypertension (DASH)-with the risk of MAFLD in the total population, and further in nonobese and obese individuals.

METHODS

We recruited 99,556 participants in the China Multi-Ethnic Cohort Study, an ongoing cohort study in less-developed southwest China. Using validated food frequency questionnaire, each participant was assigned an AMED score and a DASH score. MAFLD was ascertained as hepatic steatosis on ultrasound together with diabetes, overweight/obesity, or two other metabolic risk factors. We performed logistic regression with inverse probability of exposure weighting (IPEW) to examine associations between two dietary patterns and MAFLD, adjusting for potential confounders under the guidance of directed acyclic graphs. Further, analyses were stratified by body mass index.

RESULTS

We included 66,526 participants (age 49.5±11.0; 62.6% women), and the prevalence of MAFLD was 16.1%. Participants in the highest quintile of DASH score showed strong inverse associations with risks of MAFLD (OR = 0.85; 95% CI, 0.80-0.91; Ptrend < 0.001) compared with participants in the lowest quintile. The association between DASH and nonobese MAFLD (OR = 0.69; 95% CI, 0.61-0.78; Ptrend < 0.001) was stronger (I2 = 78.5 % ; Pheterogeneity = 0.001) than that with obese MAFLD (OR = 0.90; 95% CI, 0.83-0.98; Ptrend = 0.002). There was a null association between AMED and MAFLD risk.

CONCLUSIONS

In LEMRs, a DASH diet but not AMED was associated with MAFLD. The relationship appeared to be more pronounced in nonobese MAFLD individuals than in obese MAFLD individuals.

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

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

Impact of Genetic Polymorphism on Response to Therapy in Non-Alcoholic Fatty Liver Disease

In the last decades, the global prevalence of non-alcoholic fatty liver disease (NAFLD) has reached pandemic proportions with derived major health and socioeconomic consequences; this tendency is expected to be further aggravated in the coming years. Obesity, insulin resistance/type 2 diabetes mellitus, sedentary lifestyle, increased caloric intake and genetic predisposition constitute the main risk factors associated with the development and progression of the disease. Importantly, the interaction between the inherited genetic background and some unhealthy dietary patterns has been postulated to have an essential role in the pathogenesis of NAFLD. Weight loss through lifestyle modifications is considered the cornerstone of the treatment for NAFLD and the inter-individual variability in the response to some dietary approaches may be conditioned by the presence of different single nucleotide polymorphisms. In this review, we summarize the current evidence on the influence of the association between genetic susceptibility and dietary habits in NAFLD pathophysiology, as well as the role of gene polymorphism in the response to lifestyle interventions and the potential interaction between nutritional genomics and other emerging therapies for NAFLD, such as bariatric surgery and several pharmacologic agents.

Insights into Nonalcoholic Fatty-Liver Disease Heterogeneity

The acronym nonalcoholic fatty-liver disease (NAFLD) groups a heterogeneous patient population. Although in many patients the primary driver is metabolic dysfunction, a complex and dynamic interaction of different factors (i.e., sex, presence of one or more genetic variants, coexistence of different comorbidities, diverse microbiota composition, and various degrees of alcohol consumption among others) takes place to determine disease subphenotypes with distinct natural history and prognosis and, eventually, different response to therapy. This review aims to address this topic through the analysis of existing data on the differential contribution of known factors to the pathogenesis and clinical expression of NAFLD, thus determining the different clinical subphenotypes observed in practice. To improve our understanding of NAFLD heterogeneity and the dominant drivers of disease in patient subgroups would predictably impact on the development of more precision-targeted therapies for NAFLD.

PNPLA3, TM6SF2, and MBOAT7 Influence on Nutraceutical Therapy Response for Non-alcoholic Fatty Liver Disease: A Randomized Controlled Trial

Introduction: PNPLA3, TM6SF2, and MBOAT7 genes play a crucial role in non-alcoholic fatty liver disease (NAFLD) development and worsening. However, few data are available on their treatment response influence. The aim of this trial is to explore the effect derived from silybin-phospholipids complex (303 mg of silybin-phospholipids complex, 10 μg of vitamin D, and 15 mg of vitamin E twice a day for 6 months) oral administration in NAFLD patients carrying PNPLA3-rs738409, TM6SF2-rs58542926, or MBOAT7-rs641738 genetic variants. Materials and Methods: In all, 92 biopsy-proven NAFLD patients were grouped in 30 NAFLD wild type controls, 30 wild type treated patients, and 32 mutated treated ones. We assessed glycemia (FPG), insulinemia, HOMA-IR, aspartate and alanine aminotransferases (AST, ALT), C-reactive protein (CRP), thiobarbituric acid reactive substance (TBARS), stiffness, controlled attenuation parameter (CAP), dietary daily intake, and physical activity at baseline and end of treatment. Results: The wild-type treated group showed a significant improvement of FPG, insulinemia, HOMA-IR, ALT, CRP, and TBARS (p < 0.05), whereas no improvements were recorded in the other two study groups. NAFLD wild type treated patients showed higher possibilities of useful therapeutic outcome (p < 0.01), obtained from the prescribed therapeutic regimen, independently from age, sex, comorbidities, medications, CAP, and stiffness in comparison to the mutated group. Discussion: The assessed mutations are independently associated with no response to a silybin-based therapeutic regimen and could be considered as useful predictive markers in this context. Clinical Trial Registry Number: www.ClinicalTrials.gov, identifier: NCT04640324.

Breaking Down Barriers to Physical Activity in Patients with Nonalcoholic Fatty Liver Disease

BACKGROUND

Lifestyle changes, including physical activity, are the cornerstones of the treatment of nonalcoholic fatty liver disease (NAFLD). For unclear reasons, most NAFLD patients do not achieve the recommended amount of weekly activity.

AIMS

Our aim was to measure perceived barriers to physical activity and enablers to exercise intervention.

METHODS

Consecutive subjects aged 18-70 with NAFLD were prospectively enrolled. An exercise motivation questionnaire was administered to assess current behaviors and perceived barriers.

RESULTS

Eighty-seven subjects (60% female) were enrolled with mean age 52 years and mean body mass index (BMI) 34.5 kg/m². Metabolic comorbidities were common: 49% had hyperlipidemia, 42% hypertension, and 40% diabetes. The majority (75%) did not achieve ≥ 150 min/week of physical activity. Ninety-one percent agreed that activity was important in improving NAFLD; 88% desired to be more active. Lack of exercise resources and education from treating provider (47%), physical discomfort during exercise (44%), and time constraints (32%) were the most common barriers. Rates of fitness tracker (34%), gym (33%), exercise program (33%), and personal trainer (17%) use were low.

CONCLUSIONS

While nearly all subjects with NAFLD identify physical activity to be important and desire to be more active, only a few meet activity recommendations. This discordance is due to a perceived lack of resources and education, physical discomfort, and time constraints. Better understanding of these barriers and behaviors are important to improve morbidity and mortality in NAFLD. Future behavioral research removing the identified barriers is of great importance to global public health and should be prioritized.

Diet and exercise in NAFLD/NASH: Beyond the obvious

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

Non-Alcoholic Fatty Liver Disease in Lean and Non-Obese Individuals: Current and Future Challenges

Non-alcoholic fatty liver disease (NAFLD), which approximately affects a quarter of the world’s population, has become a major public health concern. Although usually associated with excess body weight, it may also affect normal-weight individuals, a condition termed as lean/non-obese NAFLD. The prevalence of lean/non-obese NAFLD is around 20% within the NAFLD population, and 5% within the general population. Recent data suggest that individuals with lean NAFLD, despite the absence of obesity, exhibit similar cardiovascular- and cancer-related mortality compared to obese NAFLD individuals and increased all-cause mortality risk. Lean and obese NAFLD individuals share several metabolic abnormalities, but present dissimilarities in genetic predisposition, body composition, gut microbiota, and susceptibility to environmental factors. Current treatment of lean NAFLD is aimed at improving overall fitness and decreasing visceral adiposity, with weight loss strategies being the cornerstone of treatment. Moreover, several drugs including PPAR agonists, SGLT2 inhibitors, or GLP-1 receptor agonists could also be useful in the management of lean NAFLD. Although there has been an increase in research regarding lean NAFLD, there are still more questions than answers. There are several potential drugs for NAFLD therapy, but clinical trials are needed to evaluate their efficacy in lean individuals.

Lifestyle modifications for nonalcohol-related fatty liver disease: a network meta-analysis

BACKGROUND

The prevalence of nonalcohol-related fatty liver disease (NAFLD) varies between 19% and 33% in different populations. NAFLD decreases life expectancy and increases the risks of liver cirrhosis, hepatocellular carcinoma, and requirement for liver transplantation. There is uncertainty surrounding the relative benefits and harms of various lifestyle interventions for people with NAFLD.

OBJECTIVES

To assess the comparative benefits and harms of different lifestyle interventions in the treatment of NAFLD through a network meta-analysis, and to generate rankings of the different lifestyle interventions according to their safety and efficacy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, Conference Proceedings Citation Index - Science, World Health Organization International Clinical Trials Registry Platform, and trials registers until February 2021 to identify randomised clinical trials in people with NAFLD.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or status) in people with NAFLD, whatever the method of diagnosis, age, and diabetic status of participants, or presence of non-alcoholic steatohepatitis (NASH). We excluded randomised clinical trials in which participants had previously undergone liver transplantation.

DATA COLLECTION AND ANALYSIS

We planned to perform a network meta-analysis with OpenBUGS using Bayesian methods and to calculate the differences in treatments using hazard ratios (HRs), odds ratios (ORs), and rate ratios (RaRs) with 95% credible intervals (CrIs) based on an available-participant analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance. However, the data were too sparse for the clinical outcomes. We therefore performed only direct comparisons (head-to-head comparisons) with OpenBUGS using Bayesian methods.

MAIN RESULTS

We included a total of 59 randomised clinical trials (3631 participants) in the review. All but two trials were at high risk of bias. A total of 33 different interventions, ranging from advice to supervised exercise and special diets, or a combination of these and no additional intervention were compared in these trials. The reference treatment was no active intervention. Twenty-eight trials (1942 participants) were included in one or more comparisons. The follow-up ranged from 1 month to 24 months. The remaining trials did not report any of the outcomes of interest for this review. The follow-up period in the trials that reported clinical outcomes was 2 months to 24 months. During this short follow-up period, clinical events related to NAFLD such as mortality, liver cirrhosis, liver decompensation, liver transplantation, hepatocellular carcinoma, and liver-related mortality were sparse. This is probably because of the very short follow-up periods. It takes a follow-up of 8 years to 28 years to detect differences in mortality between people with NAFLD and the general population. It is therefore unlikely that differences by clinical outcomes will be noted in trials with less than 5 years to 10 years of follow-up. In one trial, one participant developed an adverse event. There were no adverse events in any of the remaining participants in this trial, or in any of the remaining trials, which seemed to be directly related to the intervention.

AUTHORS' CONCLUSIONS

The evidence indicates considerable uncertainty about the effects of the lifestyle interventions compared with no additional intervention (to general public health advice) on any of the clinical outcomes after a short follow-up period of 2 months to 24 months in people with nonalcohol-related fatty liver disease. Accordingly, high-quality randomised clinical trials with adequate follow-up are needed. We propose registry-based randomised clinical trials or cohort multiple randomised clinical trials (a study design in which multiple interventions are trialed within large longitudinal cohorts of participants to gain efficiencies and align trials more closely to standard clinical practice), comparing aerobic exercise and dietary advice versus standard of care (exercise and dietary advice received as part of national health promotion). The reason for the choice of aerobic exercise and dietary advice is the impact of these interventions on indirect outcomes which may translate to clinical benefit. The outcomes in such trials should be mortality, health-related quality of life, decompensated liver cirrhosis, liver transplantation, and resource use measures including costs of intervention and decreased healthcare use after a minimum follow-up of eight years, to find meaningful differences in the clinically important outcomes.

Beyond the Paradigm of Weight Loss in Non-Alcoholic Fatty Liver Disease: From Pathophysiology to Novel Dietary Approaches

Current treatment recommendations for non-alcoholic fatty liver disease (NAFLD) rely heavily on lifestyle interventions. The Mediterranean diet and physical activity, aiming at weight loss, have shown good results in achieving an improvement of this liver disease. However, concerns related to compliance and food accessibility limit the feasibility of this approach, and data on the long-term effects on liver-related outcomes are lacking. Insulin resistance is a central aspect in the pathophysiology of NAFLD; therefore, interventions aiming at the improvement of insulin sensitivity may be preferable. In this literature review, we provide a comprehensive summary of the available evidence on nutritional approaches in the management of NAFLD, involving low-calorie diets, isocaloric diets, and the novel schemes of intermittent fasting. In addition, we explore the harmful role of single nutrients on liver-specific key metabolic pathways, the role of gene susceptibility and microbiota, and behavioral aspects that may impact liver disease and are often underreported in clinical setting. At present, the high variability in terms of study populations and liver-specific outcomes within nutritional studies limits the generalizability of the results and highlights the urgent need of a tailored and standardized approach, as seen in regulatory trials in Non-Alcoholic Steatohepatitis (NASH).

Lean NAFLD: an underrecognized and challenging disorder in medicine

Classically, Non-Alcoholic Fatty Liver Disease (NAFLD) has been thought to be driven by excessive weight gain and obesity. The overall greater awareness of this disorder has led to its recognition in patients with normal body mass index (BMI). Ongoing research has helped to better understand potential causes of Lean NAFLD, the risks for more advanced disease, and potential therapies. Here we review the recent literature on prevalence, risk factors, severity of disease, and potential therapeutic interventions.

A review of non-alcoholic fatty liver disease in non-obese and lean individuals

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of hepatic disorders. It represents a wide range of chronic liver diseases in patients with no history of significant alcohol consumption, starting with simple steatosis and progressing towards non-alcoholic steatohepatitis, cirrhosis, and ultimately hepatocellular carcinoma. NAFLD is usually associated with type 2 diabetes mellitus, dyslipidemia, metabolic syndrome, and obesity. This disease has mostly been studied in obese individuals; however, it has been widely reported and studied among the lean/non-obese population in recent years. The pathogenesis of NAFLD in non-obese patients is associated with various genetic predispositions, particularly a patatin-like phospholipase domain-containing protein 3 G allele polymorphism, which results in the accumulation of triglyceride in the liver and resistance to insulin. Additionally, dietary factors such as high fructose consumption seem to play a substantial role in the pathology of non-obese NAFLD. Although there is not enough evidence on the treatment of NAFLD in non-obese patients, the standard approach is to advise altering one's lifestyle in order to diminish visceral adiposity. Dietary modification, weight loss, and increased physical activity are highly recommended. We aimed to review and summarize the existing information on the prevalence, pathogenesis, genetic predispositions, diagnosis, and treatment of NAFLD in non-obese patients according to the latest literature.

Nutrigenomics and Nutrigenetics in Metabolic- (Dysfunction) Associated Fatty Liver Disease: Novel Insights and Future Perspectives

Metabolic- (dysfunction) associated fatty liver disease (MAFLD) represents the predominant hepatopathy and one of the most important systemic, metabolic-related disorders all over the world associated with severe medical and socio-economic repercussions due to its growing prevalence, clinical course (steatohepatitis and/or hepatocellular-carcinoma), and related extra-hepatic comorbidities. To date, no specific medications for the treatment of this condition exist, and the most valid recommendation for patients remains lifestyle change. MAFLD has been associated with metabolic syndrome; its development and progression are widely influenced by the interplay between genetic, environmental, and nutritional factors. Nutrigenetics and nutrigenomics findings suggest nutrition's capability, by acting on the individual genetic background and modifying the specific epigenetic expression as well, to influence patients' clinical outcome. Besides, immunity response is emerging as pivotal in this multifactorial scenario, suggesting the interaction between diet, genetics, and immunity as another tangled network that needs to be explored. The present review describes the genetic background contribution to MAFLD onset and worsening, its possibility to be influenced by nutritional habits, and the interplay between nutrients and immunity as one of the most promising research fields of the future in this context.

Perspectives on Precision Medicine Approaches to NAFLD Diagnosis and Management

Precision medicine defines the attempt to identify the most effective approaches for specific subsets of patients based on their genetic background, clinical features, and environmental factors. Nonalcoholic fatty liver disease (NAFLD) encompasses the alcohol-like spectrum of liver disorders (steatosis, steatohepatitis with/without fibrosis, and cirrhosis and hepatocellular carcinoma) in the nonalcoholic patient. Recently, disease renaming to MAFLD [metabolic (dysfunction)-associated fatty liver disease] and positive criteria for diagnosis have been proposed. This review article is specifically devoted to envisaging some clues that may be useful to implementing a precision medicine-oriented approach in research and clinical practice. To this end, we focus on how sex and reproductive status, genetics, intestinal microbiota diversity, endocrine and metabolic status, as well as physical activity may interact in determining NAFLD/MAFLD heterogeneity. All these factors should be considered in the individual patient with the aim of implementing an individualized therapeutic plan. The impact of considering NAFLD heterogeneity on the development of targeted therapies for NAFLD subgroups is also extensively discussed.