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

Editorial: Can dietary gluten restriction improve hepatic steatosis? Authors' reply

This article is linked to Armandi et al papers. To view these articles, visit https://doi.org/10.1111/apt.17941 and https://doi.org/10.1111/apt.17969.

Editorial: Can dietary gluten restriction improve hepatic steatosis?

This article is linked to Armandi et al papers. To view these articles, visit https://doi.org/10.1111/apt.17941 and https://doi.org/10.1111/apt.18025.

Short-term reduction of dietary gluten improves metabolic-dysfunction associated steatotic liver disease: A randomised, controlled proof-of-concept study

BACKGROUND

The current management of metabolic dysfunction-associated steatotic liver disease (MASLD) relies on lifestyle intervention. Prior studies have shown that nutritional wheat amylase trypsin inhibitors (ATI) activate toll-like receptor 4 on intestinal myeloid cells to enhance intestinal and extra-intestinal inflammation, including the promotion of murine MASLD, insulin resistance and liver fibrosis.

AIMS

We aimed to assess the impact of ATI (gluten)-free diet in liver as well as metabolic parameters of biopsy-proven MASLD patients.

METHODS

We performed a 6-week, proof-of-concept 1:1 randomised controlled trial of an ATI-free diet. The controls followed a balanced diet recommended by the German Nutrition Society. We assessed changes in controlled attenuation parameter (CAP), body mass index (BMI) and homeostatic model assessment of insulin resistance (HOMA-IR). Patient-reported outcomes were assessed by the CLDQ-NASH questionnaire. Forty-five patients were consecutively enrolled (21 in the intervention arm and 24 in the control arm).

RESULTS

Three patients from each arm discontinued the study. In the ATI-free diet group, a significant decrease in BMI (p = 0.018), CAP (p = 0.018) and HOMA-IR (p = 0.042) was observed at 6 weeks. The mean difference in CAP between the two arms at week 6 was 30.5 dB/m (p = 0.039), with a delta significantly higher in the ATI-free diet group (p = 0.043). Only an ATI-free diet could achieve a significant improvement in CLDQ-NASH domains (p value for total scoring: 0.013).

CONCLUSIONS

A short-term ATI-free diet leads to significant improvements in liver and metabolic parameters, as well as patient-reported outcomes with good tolerability. A larger follow-up study is justified to corroborate these findings.

CLINICAL TRIAL NUMBER

NCT04066400.

Effect of a Low-Calorie Dietary Intervention on Liver Health and Body Weight in Adults with Metabolic-Dysfunction Associated Steatotic Liver Disease (MASLD) and Overweight/Obesity: A Systematic Review and Meta-Analysis

INTRODUCTION

Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD) is a common cause of chronic liver disease. This review assessed the efficacy of a Low-Calorie Diet (LCD) on liver health and body weight in people living with MASLD and obesity.

METHODS

The study was registered with PROSPERO (CRD42021296501), and a literature search was conducted using multiple databases. The key inclusion criteria were randomised controlled trials or cohort studies, obesity/overweight and MASLD. Two authors screened abstracts, reviewed full texts and performed data extraction and quality assessment. The primary outcome was the change in the serum ALT, and secondary outcomes included the changes in the serum AST, intrahepatic lipid content (IHL), quantified non-invasively via MRI/MRS, and body weight.

RESULTS

Fifteen studies were included. The LCD reduced body weight by 9.1 kg versus the control (95%CI: -12.4, -5.8) but not serum ALT (-5.9 IU/L, -13.9, 2.0). Total Dietary Replacement (TDR) reduced IHL by -9.1% vs. the control (-15.6%, -2.6%). The Mediterranean-LCD for ≥12 months reduced ALT (-4.1 IU/L, -7.6, -0.5) and for 24 months reduced liver stiffness versus other LCDs. The Green-Mediterranean-LCD reduced IHL, independent of body weight. Limited studies assessed those of Black or Asian ethnicity, and there was heterogeneity in the methods assessing the liver fat content and fibrosis.

CONCLUSIONS

In people with MASLD and obesity, an LCD intervention reduces IHL and body weight. Trials should focus on the recruitment of Black and Asian ethnicity participants.

Dietary and pharmacological treatment in patients with metabolic-dysfunction associated steatotic liver disease

Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD) is a disease spectrum encompassing liver injury with progressive severity, tightly connected to the metabolic syndrome. Management of MASLD mostly relies on lifestyle change aiming at improving metabolic homeostasis and insulin resistance. A Mediterranean-like dietary pattern and individualized lifestyle interventions are the cornerstone of MASLD treatment. A careful evaluation of alcohol intake and active treatment of all metabolic co-morbidities are recommended. In the MASLD spectrum, the population with liver inflammation and enhanced fibrogenesis (MASH - Metabolic-dysfunction associated steatohepatitis) can progress to advanced liver disease and has been addressed as "at-risk MASH", eligible to pharmacological treatment according to FDA and EMA. Currently there is a robust therapeutic pipeline across a variety of new targets to resolve MASH or reverse fibrosis, or both. Some of these therapies have beneficial effects that extend beyond the liver, such as effects on glycaemic control, lipid profile and weight loss. For "at-risk" MASH, reversal of fibrosis by one stage or resolution of MASH with no worsening in fibrosis as a surrogate end-point will need to be accompanied by overall survival benefits. In this review, we summarize the current evidence on lifestyle interventions in MASLD as well as pharmacological approaches for fibrosing MASH that have progressed to phase II and phase III clinical trials.

The effect of vitamin D supplementation on some metabolic parameters in patients with nonalcoholic fatty liver disease: A systematic review and meta-analysis of 8 RCTs

BACKGROUND

To systematically evaluate the effects of vitamin D supplementation in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

National Library of Medicine, Cochrane Library, Elsevier, China National Knowledge Infrastructure, Web of Science, WANFANG databases, and Google Scholar were retrieved to collect relevant randomized controlled trials, which are published from the earliest records the time the database was created to April 2023. Meta-analysis was conducted by using Review Manager 5.4 software after evaluating in terms of inclusion and exclusion criteria. The outcome indicators include 25-hydroxyvitamin D [25(OH)D] levels, insulin resistance index (homeostasis model assessment of insulin resistance), fasting blood glucose, and fasting insulin levels (FINS).

RESULTS

Eight randomized controlled trials with a total of 657 patients are included. Vitamin D supplementation increased 25(OH)D levels significantly (mean difference [MD] = 2.01, 95% confidence intervals [CI]: 0.94 to 3.08, P < .05) and vitamin D supplementation had a significant effect on insulin resistance index (MD = -0.54, 95% CI: -1.28 to 0.20, P = .16), fasting glucose (MD = -0.59, 95% CI: -1.50 to 0.32, P = .20), and FINS levels (MD = -0.30, 95% CI: -0.77 to 0.17, P = .21) had no significant effect.

CONCLUSION

Vitamin D supplementation improves 25(OH)D levels in patients with nonalcoholic fatty liver disease, but there is no effect on homeostasis model assessment of insulin resistance, fasting blood glucose, or FINS.

Metagenomic signatures reveal the key role of phloretin in amelioration of gut dysbiosis attributed to metabolic dysfunction-associated fatty liver disease by time-dependent modulation of gut microbiome

The importance of gut-liver axis in the pathophysiology of metabolic dysfunction-associated fatty liver disease (MAFLD) is being investigated more closely in recent times. However, the inevitable changes in gut microbiota during progression of the disease merits closer look. The present work intends to assess the time-dependent gut dysbiosis in MAFLD, its implications in disease progression and role of plant-derived prebiotics in its attenuation. Male C57BL/6J mice were given western diet (WD) for up to 16 weeks and phloretin was administered orally. The fecal samples of mice were collected every fourth week for 16 weeks. The animals were sacrificed at the end of the study and biochemical and histological analyses were performed. Further, 16S rRNA amplicon sequencing analysis was performed to investigate longitudinal modification of gut microbiome at different time points. Findings of our study corroborate that phloretin alleviated the metabolic changes and mitigated circulating inflammatory cytokines levels. Phloretin treatment resists WD induced changes in microbial diversity of mice and decreased endotoxin content. Prolonged exposure of WD changed dynamics of gut microbiota abundance and distribution. Increased abundance of pathogenic taxa like Desulfovibrionaceae, Peptostreptococcus, Clostridium, and Terrisporobacter was noted. Phloretin treatment not only reversed this dysbiosis but also modulated taxonomic signatures of beneficial microbes like Ruminococcus, Lactobacillus, and Alloprevotella. Therefore, the potential of phloretin to restore gut eubiosis could be utilized as an intervention strategy for the prevention of MAFLD and related metabolic disorders.

Research Priorities for Precision Medicine in NAFLD

NAFLD is a multisystem condition and the leading cause of chronic liver disease globally. There are no approved NAFLD-specific dugs. To advance in the prevention and treatment of NAFLD, there is a clear need to better understand the pathophysiology and genetic and environmental risk factors, identify subphenotypes, and develop personalized and precision medicine. In this review, we discuss the main NAFLD research priorities, with a particular focus on socioeconomic factors, interindividual variations, limitations of current NAFLD clinical trials, multidisciplinary models of care, and novel approaches in the management of patients with NAFLD.

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.

Spiroganodermaines A-G from Ganoderma species and their activities against insulin resistance and renal fibrosis

Ganoderma mushrooms are a renowned Chinese medicine and functional food used worldwide. Seven undescribed spiro Ganoderma meroterpenoids spiroganodermaines A-G were isolated from Ganoderma species. Their structures were characterized by using spectroscopic, computational and X-ray diffraction methods. Biological studies showed that (+)-spiroganodermaine G significantly activates glucose uptake and IRS1 phosphorylation in insulin resistance C2C12 cells. Furthermore, (-)-spiroganodermaine G inhibits the expressions of fibronectin and α-SMA in TGF-β1 induced NRK-52E cells. These findings demonstrate the potential of Ganoderma meroterpenoids as medicines and dietary supplements.

Reduction in the risk of major adverse cardiovascular events with the BET protein inhibitor apabetalone in patients with recent acute coronary syndrome, type 2 diabetes, and moderate to high likelihood of non-alcoholic fatty liver disease

Background

Nonalcoholic fatty liver disease (NAFLD) is common among patients with type 2 diabetes mellitus (T2DM) and is associated with increased risk for coronary atherosclerosis and acute cardiovascular (CV) events. We employed the validated, non-invasive Angulo NAFLD fibrosis score (FS) in an intervention study in patients with T2DM and recent acute coronary syndrome (ACS) to determine the association of FS with CV risk and treatment response to apabetalone. Apabetalone is a novel selective inhibitor of the second bromodomain of bromodomain and extra-terminal (BET) proteins, epigenetic regulators of gene expression.

Methods

The Phase 3 BETonMACE trial compared apabetalone with placebo in 2,425 patients with T2DM and recent ACS. In this post hoc analysis, we evaluated the impact of apabetalone therapy on CV risk, defined as a composite of major adverse cardiovascular events (MACE: CV death, non-fatal myocardial infarction [MI], or stroke) and hospitalization for heart failure (HHF) in two patient categories of FS that reflect the likelihood of underlying NAFLD. Patients were initially classified into three mutually exclusive categories according to a baseline Angulo FS <-1.455 (F0-F2), -1.455 to 0.675 (indeterminant), and >0.675 (F3-F4), where F0 through F4 connote fibrosis severity none, mild, moderate, severe, and cirrhosis, respectively. The composite of ischemic MACE and HHF in the placebo group was higher in indeterminant and F3-F4 categories compared to the F0-F2 category (17.2% vs 15.0% vs 9.7%). Therefore, for the present analysis, the former two categories were combined into an elevated NAFLD CVD risk group (FS+) that was compared with the F0-F2 group (lower NAFLD risk, FS_0-2).

Results

In 73.7% of patients, FS was elevated and consistent with a moderate-to-high likelihood of advanced liver fibrosis (FS+); 26.3% of patients had a lower FS (FS_0-2). In the placebo group, FS+ patients had a higher incidence of ischemic MACE and HHF (15.4%) than FS_0-2 patients (9.7%). In FS+ patients, addition of apabetalone to standard of care treatment lowered the rate of ischemic MACE compared with placebo (HR = 0.79; 95% CI 0.60-1.05; p=0.10), HHF (HR = 0.53; 95% CI 0.33-0.86; p=0.01), and the composite of ischemic MACE and HHF (HR = 0.76; 95% CI 0.59-0.98; p=0.03). In contrast, there was no apparent benefit of apabetalone in FS_0-2 patients (HR 1.24; 95% CI 0.75-2.07; p=0.40; HR 1.12; 95% CI 0.30-4.14; p=0.87; and HR 1.13; 95% CI 0.69-1.86; p=0.62, respectively). Over a median duration of 26.5 months, FS increased from baseline in both treatment groups, but the increase was smaller in patients assigned to apabetalone than to placebo (p=0.04).

Conclusions

Amongst patients with T2DM, recent ACS, and a moderate-to-high likelihood of advanced liver fibrosis, apabetalone was associated with a significantly lower rate of ischemic MACE and HHF and attenuated the increase in hepatic FS over time.

Major royal jelly proteins alleviate non-alcoholic fatty liver disease in mice model by regulating disordered metabolic pathways

Nonalcoholic fatty liver disease (NAFLD), the major cause of global chronic hepatic injury, has obtained increasing attention while the current drug treatment still laid safety hazards. Major royal jelly proteins (MRJPs), the water-soluble proteins enriched in royal jelly (RJ), were applied to study its effects on improving NAFLD in the NAFLD mouse model. Herein, we demonstrated that intaking of 250-500 mg/kg/day MRJPs significantly decreased the rate of obesity, dyslipidemia, hepatic steatosis, and insulin resistance. Next, TOF to MRM ("TM") widely targeted metabolomics (untargeted metabolomics + widely targeted metabolomics) was further used to explore the potential mechanism, and we found that 500 mg/kg MRJPs alleviated lipid metabolism, oxidative stress, and inflammation mainly by regulating the metabolisms of alpha-linolenic acid, linoleic acid, arachidonic acid, and biosynthesis of unsaturated fatty acids. Moreover, by detecting multiple oxidative stress factors and inflammatory cytokines, we found that MRJPs indeed exerted antioxidant and anti-inflammatory effects. Together, we demonstrated that MRJPs could mediate the progress of NAFLD through the "multi-component-multi-target-multi-pathway" mechanism, which could be considered as an ideal functional food in alleviating NAFLD. PRACTICAL APPLICATIONS: Royal jelly (RJ) is a bee product with high nutritional value. Major royal jelly proteins (MRJPs) are water-soluble proteins in RJ. Our research showed that MRJPs significantly ameliorated NAFLD induced by a high-fat diet in mice, suggesting that MRJPs could be used as an active ingredient to help improve NAFLD, which was beneficial for the development of related functional foods and the economic value of RJ. Moreover, the metabolic pathways involved in the ameliorative effect of MRJPs were investigated, which provided new ideas for the prevention and treatment of NAFLD.

Effect of intensive weight-loss intervention on metabolic, ultrasound and anthropometric parameters among patients with obesity and non-alcoholic fatty liver disease: an RCT

Background

Lifestyle intervention is the mainstay therapy for Non-Alcoholic Fatty Liver Disease (NAFLD). We aimed to assess the efficacy of an intensive (9 contact points in 6 months) weight-loss intervention among patients with obesity (BMI 25–39.9 kg/m²) and NAFLD in north India.

Methods

A total of 140 patients (18–60 years) with obesity and NAFLD were randomized into intervention (n = 70) and control (n = 70) groups, at a tertiary-care hospital. Weight, anthropometric parameters, Controlled Attenuation Parameter (CAP), Liver Stiffness Measurement (LSM), liver enzymes, grade of fatty liver and HOMA-IR were measured at baseline (T₀) and 6 months (T₆). There was a high drop-out, exacerbated by the Covid-19 pandemic. Completers comprised of 59 participants (n = 30 intervention, n = 29 control). Intention to treat analysis was done.

Results

At T₆, ALT normalized in significantly higher (p = 0.03) number of cases in the intervention arm (66.7%) versus control arm (18.2%). No significant improvement was seen in other metabolic, ultrasound or anthropometric outcomes. Weight (p < 0.001), AST (p = 0.01), ALT (p = 0.02), body fat% (p < 0.001), WC (p < 0.001) and CAP (p < 0.001) significantly improved within the intervention arm along with a trend of improvement in steatosis and HOMA-IR. Control group showed significant decrease in weight (p < 0.001), WC (p < 0.001) and CAP (p = 0.02). Twice the number of patients in intervention arm (46.7%) lost ≥5% weight, compared to control arm (24.1%) (p = 0.07).

Conclusion

The intensive weight-loss intervention was not effective in improving the treatment outcomes among patients with obesity and NAFLD. However, given the potential of our intervention, we recommend larger trials with more intensive weight-loss interventions.

Quercetin Reduces Lipid Accumulation in a Cell Model of NAFLD by Inhibiting De Novo Fatty Acid Synthesis through the Acetyl-CoA Carboxylase 1/AMPK/PP2A Axis

Dysregulation of de novo lipogenesis (DNL) has recently gained strong attention as being one of the critical factors that contribute to the assessment of non-alcoholic fatty liver disease (NAFLD). NAFLD is often diagnosed in patients with dyslipidemias and type 2 diabetes; thus, an interesting correlation can be deduced between high hematic free fatty acids and glucose excess in the DNL dysregulation. In the present study, we report that, in a cellular model of NAFLD, the coexistence of elevated glucose and FFA conditions caused the highest cellular lipid accumulation. Deepening the molecular mechanisms of the DNL dysregulation—RT-qPCR and immunoblot analysis demonstrated increased expression of mitochondrial citrate carrier (CiC), cytosolic acetyl-CoA carboxylase 1 (ACACA), and diacylglycerol acyltransferase 2 (DGAT2) involved in fatty acids and triglycerides synthesis, respectively. XBP-1, an endoplasmic reticulum stress marker, and SREBP-1 were the transcription factors connected to the DNL activation. Quercetin (Que), a flavonoid with strong antioxidant properties, and noticeably reduced the lipid accumulation and the expression of SREBP-1 and XBP-1, as well as of their lipogenic gene targets in steatotic cells. The anti-lipogenic action of Que mainly occurs through a strong phosphorylation of ACACA, which catalyzes the committing step in the DNL pathway. The high level of ACACA phosphorylation in Que-treated cells was explained by the intervention of AMPK together with the reduction of enzymatic activity of PP2A phosphatase. Overall, our findings highlight a direct anti-lipogenic effect of Que exerted through inhibition of the DNL pathway by acting on ACACA/AMPK/PP2A axis; thus, suggesting this flavonoid as a promising molecule for the NAFLD treatment.

NAFLD and NASH: The Metabolically Diseased Liver

Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common chronic liver disease, with a global prevalence of approximately 24% in the general population. It is caused by fat accumulation in the liver secondary to insulin resistance, visceral obesity, and/or features of metabolic syndrome. A genetic susceptibility contributes to the phenotype, accounting for a more severe course of liver disease and the observed clinical variability. In fact, despite liver steatosis being considered a relatively benign entity, inflammation related to oxidative stress and lipid-derived damage may lead to non-alcoholic steatohepatitis (NASH), which constitutes the progressive disease. Accumulation of hepatic fibrosis can lead to cirrhosis and provide the environment for hepatocellular carcinoma. Obese and diabetic individuals represent a well-acknowledged high risk population. The assessment of liver fibrosis plays a crucial role in clinical setting, as liver-related mortality increases parallel to fibrosis stage. A liver biopsy is currently considered the reference standard for the diagnosis of NASH and the fibrosis stage, but many non-invasive tools are used with the aim of replacing histology for diagnosis and prognosis purposes. Blood based scores and liver stiffness are the most widely used and validated tools to assess liver fibrosis. Management of NAFLD resides on environmental interventions, including diet and physical activity to induce weight loss, and avoiding harmful nutrients, including fructose-sweetened beverages and high glycemic index foods, that are directly implied in liver injury. Multiple trials with investigational drugs are currently explored to treat fibrosing NASH, with promising results and it can be expected that a liver direct therapy aiming at steatohepatitis and fibrosis will become available soon.

The gut microbiota instructs the hepatic endothelial cell transcriptome

The gut microbiota affects remote organ functions but its impact on organotypic endothelial cell (EC) transcriptomes remains unexplored. The liver endothelium encounters microbiota-derived signals and metabolites via the portal circulation. To pinpoint how gut commensals affect the hepatic sinusoidal endothelium, a magnetic cell sorting protocol, combined with fluorescence-activated cell sorting, was used to isolate hepatic sinusoidal ECs from germ-free (GF) and conventionally raised (CONV-R) mice for transcriptome analysis by RNA sequencing. This resulted in a comprehensive map of microbiota-regulated hepatic EC-specific transcriptome profiles. Gene Ontology analysis revealed that several functional processes in the hepatic endothelium were affected. The absence of microbiota influenced the expression of genes involved in cholesterol flux and angiogenesis. Specifically, genes functioning in hepatic endothelial sphingosine metabolism and the sphingosine-1-phosphate pathway showed drastically increased expression in the GF state. Our analyses reveal a prominent role for the microbiota in shaping the transcriptional landscape of the hepatic endothelium.

•

Germ-free mice show transcriptome differences in the liver sinusoidal endothelium

•

Gut microbiota suppresses sphingolipid metabolism in the hepatic sinusoidal endothelium

•

Cholesterol flux and angiogenesis in liver endothelium is microbiota-regulated

•

Bacteroides thetaiotaomicron did not affect expression levels of the identified genes