FGF19 and FGF21: In NASH we trust

Innovative nanomedicine approaches for the management of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disorder globally. The prevalence of NAFLD in the general population is estimated to be 25-30 %, making it the most common chronic liver condition in China as well as worldwide. Given the escalating disease burden and the scarcity of effective therapeutic interventions, there is a pressing unmet clinical need. Consequently, the development of novel pharmaceuticals has emerged as a pivotal research focus in recent years. Moreover, the advent of nano-delivery technology offers innovative solutions for NAFLD drug therapy. This paper presents a comprehensive examination of the pathogenesis and therapeutic targets of NAFLD. It critically reviews the latest advancements in nanomedicine research pertinent to NAFLD treatment. The review synthesizes a broad range of research findings to bridge the gap between current knowledge and emerging therapeutic strategies, and aims to inform and guide future research directions in NAFLD management.

Tryptophan Hydroxylase 1 Regulates Tryptophan and Its Metabolites

Tryptophan hydroxylase (Tph), the rate-limiting enzyme of serotonin (5-hydroxytryptophan; 5-HT) synthesis, exists in two isoforms, Tph1 and Tph2. Tph1 upregulates peripheral 5-HT synthesis and blood 5-HT levels, whereas Tph2 upregulates brain 5-HT synthesis. Here, we show that plasma and brain levels of tryptophan and its metabolites, including 5-HT, 5-hydroxy indoleacetic acid, indolepropionic acid, indole-3-acetic acid, kynurenine, and xanthurenic acid, are decreased in young (8-week-old) Tph1-mutant mice compared with age-matched wild-type mice. In older (7-month-old) Tph1-mutants, the decreases in tryptophan and its metabolites outside the 5-HT pathway were diminished. Although single-housed Tph1 mutants displayed age-related alterations in food intake, body weight, and plasma FGF21 levels, blood glucose levels were lower in both young and older Tph1 mutants compared with age-matched wild-type mice. These findings suggest that Tph1 regulates tryptophan and its metabolites in the plasma and brain, as well as blood glucose homeostasis.

Clinical Trial: A Phase 2b Study to Evaluate the Efficacy and Safety of MK-3655 in Individuals With Pre-Cirrhotic MASH

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a metabolic regulator with demonstrated efficacy for the treatment of metabolic dysfunction-associated steatohepatitis (MASH). FGF21 signals through 'c' isoforms of the FGF receptors (FGFR) 1-3 and the co-receptor β-klotho.

AIMS

We report the safety and efficacy of MK-3655, a monoclonal antibody that binds β-klotho and selectively activates the FGFR1c/β-klotho co-receptor complex, in patients with pre-cirrhotic MASH.

METHODS

Phase 2b, randomised, multicenter, double-blind, placebo-controlled, parallel-group study in patients with pre-cirrhotic MASH (NAS ≥ 4 and MASH CRN fibrosis score Stage 2 or 3). Participants were randomised 1:1:1:1 to receive MK-3655 50 mg, 100 mg, 300 mg, or matching placebo subcutaneously every 4 weeks. The primary endpoint was MASH resolution without worsening of fibrosis by histology at Week 52. An interim analysis (IA) of liver fat content (LFC) was planned once ≥ 25 participants per treatment group completed an MRI-PDFF assessment at Week 24.

RESULTS

Among 183 participants, mean BMI was 33.4 kg/m2, mean LFC was 18.1%, and 52.5% had type 2 diabetes. At the IA, the differences from placebo in relative reduction from baseline in LFC were assessed as insufficient for continuation of the trial. Among participants with Week 24 LFC assessment, percent relative reductions from baseline (LS mean difference vs. placebo) for MK-3655 50 mg (N = 33), 100 mg (N = 36), and 300 mg (N = 31), were 19.1%, 19.0%, and 26.1%, respectively. MK-3655 was generally well tolerated.

CONCLUSIONS

In patients with pre-cirrhotic MASH, treatment with MK-3655 resulted in a modest reduction in LFC at 24 weeks.

CLINICAL TRIAL NUMBER

EudraCT: 2019-003048-63; NCT: 04583423.

Therapeutic landscape of metabolic dysfunction-associated steatohepatitis (MASH)

Metabolic dysfunction-associated steatotic liver disease (MASLD) and its severe subgroup metabolic dysfunction-associated steatohepatitis (MASH) have become a global epidemic and are driven by chronic overnutrition and multiple genetic susceptibility factors. The physiological outcomes include hepatocyte death, liver inflammation and cirrhosis. The first therapeutic for MASLD and MASH, resmetirom, has recently been approved for clinical use and has energized this therapeutic space. However, there is still much to learn in clinical studies of MASH, such as the scale of placebo responses, optimal trial end points, the time required for fibrosis reversal and side effect profiles. This Review introduces aspects of disease pathogenesis related to drug development and discusses two main therapeutic approaches. Thyroid hormone receptor-β agonists, such as resmetirom, as well as fatty acid synthase inhibitors, target the liver and enable it to function within a toxic metabolic environment. In parallel, incretin analogues such as semaglutide improve metabolism, allowing the liver to self-regulate and reversing many aspects of MASH. We also discuss how combinations of therapeutics could potentially be used to treat patients.

Evaluating the Effectiveness of Pegbelfermin in MASH-Associated Hepatic Fibrosis A Meta-Analysis and Systematic Review of Randomized Controlled Trials

Introduction

Metabolic dysfunction-associated steatohepatitis (MASH), an advanced form of fatty liver disease, is characterized by liver inflammation and fibrosis, with an emerging interest in fibroblast growth factor (FGF)-21 analogs, particularly pegbelfermin (PGBF). This study evaluates the efficacy and safety of PGBF in treating MASH-associated hepatic fibrosis.

Methods

This meta-analysis followed Cochrane guidelines and PRISMA standards. A comprehensive search of databases up to January 2023 focused on randomized controlled trials (RCTs) comparing PGBF to placebo for MASH. Meta-analyses were performed with RevMan 5.4 using a random-effects model.

Results

Data from 452 participants across three RCTs were analyzed. Significant improvements in adiponectin concentration were observed in both the 10 mg [MD = 18.23, 95% CI (6.35, 30.11), p = 0.003] and 20 mg [MD = 18.09, 95% CI (5.88, 30.31), p = 0.004] PGBF groups compared to placebo. Significant reductions in PRO-C3 concentration were noted in both the 10 mg [MD = -25.50, 95% CI (-43.95, -7.05), p = 0.007] and 20 mg [MD = -19.54, 95% CI (-33.33, -5.76), p = 0.005] groups. Significant improvement in MASH was seen in the 10 mg group [RR = 2.84, 95% CI (1.18, 6.78), p = 0.02] but not in the 20 mg group. No significant improvements in liver stiffness, Modified Ishak scores, collagen proportionate area, ALT and AST levels, or treatment-emergent adverse events (TEAEs) were observed in either dosage group.

Conclusions

Pegbelfermin, a promising therapy for MASH fibrosis, has demonstrated effectiveness at 10 mg, significantly improving MASH and biomarkers including adiponectin and PRO-C3, while maintaining a generally safe profile.

Current Therapeutic Landscape for Metabolic Dysfunction-Associated Steatohepatitis

In recent years, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been proposed to better connect liver disease to metabolic dysfunction, which is the most common chronic liver disease worldwide. MASLD affects more than 30% of individuals globally, and it is diagnosed by the combination of hepatic steatosis and obesity, type 2 diabetes, or two metabolic risk factors. MASLD begins with the buildup of extra fat, often greater than 5%, within the liver, causing liver hepatocytes to become stressed. This can proceed to a more severe form, metabolic dysfunction-associated steatohepatitis (MASH), in 20-30% of people, where inflammation in the liver causes tissue fibrosis, which limits blood flow over time. As fibrosis worsens, MASH may lead to cirrhosis, liver failure, or even liver cancer. While the pathophysiology of MASLD is not fully known, the current "multiple-hits" concept proposes that dietary and lifestyle factors, metabolic factors, and genetic or epigenetic factors contribute to elevated oxidative stress and inflammation, causing liver fibrosis. This review article provides an overview of the pathogenesis of MASLD and evaluates existing therapies as well as pharmacological drugs that are currently being studied in clinical trials for MASLD or MASH.

Fibroblast growth factor 21: a novel link in the development and treatment of metabolic disorders

In recent years, fibroblast growth factor 21 (FGF21) has garnered increasing attention as a metabolic regulator. It plays a role in the development of tissue insulin sensitivity, exerts beneficial effects on carbohydrate and lipid metabolism, and exhibits antihyperglycemic and antilipidemic properties. Elevated FGF21 levels have been observed in patients with type 2 diabetes, obesity, non-alcoholic fatty liver disease, and a range of other conditions. This may indicate either resistance to FGF21 or a compensatory response to metabolic stress. Evidence suggests that FGF21 can be considered both a marker of several metabolic disorders and a potential therapeutic agent for the treatment of significant societal health issues. Objective. The objective of this review is to summarize the data published to date in the literature, including meta-analyses, reviews, and original studies, focusing on the diagnostic and potential therapeutic role of FGF21 in metabolic disorders.

Reversion of metabolic dysfunction-associated steatohepatitis by skeletal muscle-directed FGF21 gene therapy

The highly prevalent metabolic dysfunction-associated steatohepatitis (MASH) is associated with liver steatosis, inflammation, and hepatocyte injury, which can lead to fibrosis and may progress to hepatocellular carcinoma and death. New treatment modalities such as gene therapy may be transformative for MASH patients. Here, we describe that one-time intramuscular administration of adeno-associated viral vectors of serotype 1 (AAV1) encoding native fibroblast growth factor 21 (FGF21), a key metabolic regulator, resulted in sustained increased circulating levels of the factor, which mediated long-term (>1 year) MASH and hepatic fibrosis reversion and halted development of liver tumors in obese male and female mouse models. AAV1-FGF21 treatment also counteracted obesity, adiposity, and insulin resistance, which are significant drivers of MASH. Scale-up to large animals successfully resulted in safe skeletal muscle biodistribution and biological activity in key metabolic tissues. Moreover, as a step toward the clinic, circulating FGF21 levels were characterized in obese, insulin-resistant and MASH patients. Overall, these results underscore the potential of the muscle-directed AAV1-FGF21 gene therapy to treat MASH and support its clinical translation.

Dawn of an era of effective treatments for MAFLD

Fatty liver disease is a commonly occurring disease resulting in hepatic and extrahepatic complications. To date, there have been few available treatments beyond conventional lifestyle modification. While lifestyle modifications resulting in weight loss >10% have shown to be beneficial for metabolic dysfunction‐associated steatohepatitis (MASH), for the majority of patients, this is difficult to achieve. The recent approval of resmetirom (a thyroid hormone receptor beta agonist) by the Food and Drug Administration following positive results for histological outcomes in a phase 3 trial has opened the door for new treatments for metabolic (dysfunction)‐associated fatty liver disease (MAFLD) and MASH. There are currently a number of phase 3 trials targeting a variety of signaling pathways involved in the pathogenesis of metabolic steatohepatitis that are also promising. This review focuses on the currently available treatments for MAFLD and MASH, ongoing phase 3 clinical trials, and unresolved controversies in clinical trials in this area.

Drug treatment for metabolic dysfunction-associated steatotic liver disease: Progress and direction

Metabolic dysfunction-associated steatotic liver disease (MASLD), also called non-alcoholic fatty liver disease, is the most epidemic chronic liver disease worldwide. Metabolic dysfunction-associated steatohepatitis (MASH) is the critical stage of MASLD, and early diagnosis and treatment of MASH are crucial for reducing the incidence of intrahepatic and extrahepatic complications. So far, pharmacotherapeutics for the treatment of MASH are still a major challenge, because of the complexity of the pathogenesis and heterogeneity of MASH. Many agents under investigation have shown impressive therapeutic effects by targeting different key pathways, including the attenuation of steatohepatitis or fibrosis or both. It is notable that thyroid hormone receptor-β agonist, resmetirom has become the first officially approved drug for treating MASH with fibrosis. Other agents such as peroxisome proliferator-activated receptor agonists, glucagon-like peptide-1 analogs, and fibroblast growth factor 21 analogs are awaiting approval. This review focuses on the current status of drug therapy for MASH and summarizes the latest results of new medications that have completed phase 2 or 3 clinical trials, and presents the future directions and difficulties of new drug research for MASH.

The gut-liver axis: emerging mechanisms and therapeutic approaches for nonalcoholic fatty liver disease and type 2 diabetes mellitus

Nonalcoholic fatty liver disease (NAFLD), more appropriately known as metabolic (dysfunction) associated fatty liver disease (MAFLD), a prevalent condition in type 2 diabetes mellitus (T2DM) patients, is a complex condition involving hepatic lipid accumulation, inflammation, and liver fibrosis. The gut-liver axis is closely linked to metabolic dysfunction, insulin resistance, inflammation, and oxidative stress that are leading to the cooccurrence of MAFLD and T2DM cardiovascular diseases (CVDs). The purpose of this review is to raise awareness about the role of the gut-liver axis in the progression of MAFLD, T2DM and CVDs with a critical analysis of available treatment options for T2DM and MAFLD and their impact on cardiovascular health. This study analysed over 100 articles on this topic, using online searches and predefined keywords, to understand and summarise published research. Numerous studies have shown a strong correlation between gut dysfunction, particularly the gut microbiota and its metabolites, and the occurrence and progression of MAFLD and type 2 diabetes mellitus (T2DM). Herein, this article also examines the impact of the gut-liver axis on MAFLD, T2DM, and related complications, focusing on the role of gut microbiota dysbiosis in insulin resistance, T2DM and obesity-related cardiovascular complications. The study suggests potential treatment targets for MAFLD linked to T2DM, focusing on cardiovascular outcomes and the molecular mechanism of the gut-liver axis, as gut microbiota dysbiosis contributes to obesity-related metabolic abnormalities.

Compromised macrophages contribute to progression of MASH to hepatocellular carcinoma in FGF21KO mice

Metabolic dysfunction-associated steatohepatitis is well accepted as a potential precursor of hepatocellular carcinoma. Previously, we reported that fibroblast growth factor 21 (FGF21) revealed a novel anti-inflammatory activity via inhibiting the TLR4-IL-17A signaling, which could be a potential anticarcinogenetic mechanism to prevent to MASH-HCC transition. Here, we set out to determine whether FGF21 has a major impact on Kupffer cells' (KCs) ability during MASH-HCC transition. We found aberrant hepatic FGF21 and KC pool in human MASH-HCC. Lack of FGF21 up-regulated ALOX15, which converted the oxidized fatty acids to induce excessive KC death and mobilization of monocyte-derived macrophages (MoMFs) for KC replacement. Lack of FGF21 oversupplied free fatty acids for sphingosine-1-phosphate (S1P) cascade synthesis to mediate MASH-HCC transition via S1P-YAP signaling and cross-talk between tumor cells and macrophages. In conclusion, lack of FGF21 accelerated MASH-HCC transition via the S1P-AP signaling. Compromised MoMFs could present as tumor-associated macrophage phenotype rendering tumor immune microenvironment for MASH-HCC transition.

Efficacy and Safety of Fibroblast Growth Factor 21 Analogues for Metabolic Dysfunction-Associated Steatohepatitis: A Systematic Review and Meta-Analysis

INTRODUCTION

Fibroblast growth factor 21 (FGF21) analogues may benefit patients with metabolic dysfunction-associated steatohepatitis (MASH). We aimed to compare the efficacy and safety of FGF21 analogues versus placebo for treating patients with MASH in randomized controlled trials (RCTs).

METHODS

We searched PubMed, Embase, and the Cochrane Library. Primary outcomes were fibrosis improvement ≥1 stage without worsening of MASH and MASH resolution without worsening of fibrosis. Secondary outcomes were relative reduction ≥30% of the hepatic fat fraction (HFF) measured by magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) and adverse events (AEs).

RESULTS

We included 7 RCTs (886 patients). FGF21 analogues had a higher probability of fibrosis improvement ≥1 stage without worsening of MASH (RR: 1.54; 95% CI: 1.07, 2.22), MASH resolution without worsening of fibrosis (RR: 3.31; 95% CI: 1.80, 6.06), and reduction ≥30% in the HFF by MRI-PDFF (RR: 3.03; 95% CI: 2.12, 4.33) than placebo, without significant difference in the risk of AEs. Subgroup analyses by the stage of fibrosis showed that FGF21 analogues improved fibrosis only among patients with fibrosis stages F1-F3.

CONCLUSION

FGF21 analogues appear to be an effective and safe treatment option for patients with MASH, although the impact on fibrosis improvement may be limited to non-cirrhotic patients.

Endocrine fibroblast growth factors in domestic animals

Fibroblast growth factors (FGFs) are a group of structurally homologous yet functionally pleiotropic proteins. Canonical and intracellular FGFs have primarily autocrine or paracrine effects. However, the FGF19 subfamily, composed of FGF15/19, FGF21, and FGF23, act as endocrine hormones that regulate bile acid, metabolic, and phosphorus homeostasis, respectively. Current research in human and rodent models demonstrates the potential of these endocrine FGFs to target various diseases, including disorders of inherited hypophosphatemia, chronic liver disease, obesity, and insulin resistance. Many diseases targeted for therapeutic use in humans have pathophysiological overlaps in domestic animals. Despite the potential clinical and economic impact, little is known about endocrine FGFs and their signaling pathways in major domestic animal species compared with humans and laboratory animals. This review aims to describe the physiology of these endocrine FGFs, discuss their current therapeutic use, and summarize the contemporary literature regarding endocrine FGFs in domestic animals, focusing on potential future directions.

FGF21 agonists: An emerging therapeutic for metabolic dysfunction-associated steatohepatitis and beyond

The worldwide epidemics of obesity, hypertriglyceridemia, dyslipidaemia, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) represent a major economic burden on healthcare systems. Patients with at-risk MASH, defined as MASH with moderate or significant fibrosis, are at higher risk of comorbidity/mortality, with a significant risk of cardiovascular diseases and/or major adverse liver outcomes. Despite a high unmet medical need, there is only one drug approved for MASH. Several drug candidates have reached the phase III development stage and could lead to several potential conditional drug approvals in the coming years. Within the armamentarium of future treatment options, FGF21 analogues hold an interesting position thanks to their pleiotropic effects in addition to their significant effect on both MASH resolution and fibrosis improvement. In this review, we summarise preclinical and clinical data from FGF21 analogues for MASH and explore additional potential therapeutic indications.

Pathophysiological Relationship between Type 2 Diabetes Mellitus and Metabolic Dysfunction-Associated Steatotic Liver Disease: Novel Therapeutic Approaches

Type 2 diabetes mellitus (T2DM), often featuring hyperglycemia or insulin resistance, is a global health concern that is increasing in prevalence in the United States and worldwide. A common complication is metabolic dysfunction-associated steatotic liver disease (MASLD), the hepatic manifestation of metabolic syndrome that is also rapidly increasing in prevalence. The majority of patients with T2DM will experience MASLD, and likewise, individuals with MASLD are at an increased risk for developing T2DM. These two disorders may act synergistically, in part due to increased lipotoxicity and inflammation within the liver, among other causes. However, the pathophysiological mechanisms by which this occurs are unclear, as is how the improvement of one disorder can ameliorate the other. This review aims to discuss the pathogenic interactions between T2D and MASLD, and will highlight novel therapeutic targets and ongoing clinical trials for the treatment of these diseases.

Computational study of novel natural agonists targeting farnesoid X receptor

The farnesoid X receptor (FXR) is a crucial therapeutic target for treating non-alcoholic steatohepatitis (NASH). Although obeticholic acid (OCA) as a FXR agonist presents good efficacy, the safety data such as severe pruritus should be carefully considered. To discover new medications, we screen and choose the optimal compounds from ZINC15 database that may agonistically interact with FXR. We utilized the DS19 software to assist us in conducting the computer-aided structure based virtual screening to discover potential FXR agonists. After LibDock scores were determined by screening, their absorption, distribution, metabolism, excretion and toxicity predictions were examined. To determine the binding affinity between the chosen drugs and FXR, molecule docking was utilized. Molecular dynamics simulation was utilized to evaluate the stabilization of the ligand-FXR complex in its native environment. Higher binding affinity and stability with FXR were observed for ZINC000013374322 and ZINC000006036327, as two novel natural compounds, with lower rodent carcinogenicity, Ames mutagenicity, no hepatotoxicity and non-inhibitors of CYP2D6. They could stably exist in the environment, possess favorable potential energy and exert pharmacological effects at lower doses. Furthermore, ZINC000006036327 had lower skin irritancy and sensitization potential compared to OCA, also suggest the possibility of improved skin itching occurrence. ZINC000013374322 and ZINC000006036327 were found to be the best leading compounds to be FXR agonists. They are chosen as safe candidates for FXR target medicine, which play comparable pharmacological effects at lower doses.

The effects of exercise on FGF21 in adults: a systematic review and meta-analysis

Background

Fibroblast growth factor 21 (FGF21) is a key hormone factor that regulates glucose and lipid homeostasis. Exercise may regulate its effects and affect disease states. Therefore, we sought to determine how exercise affects FGF21 concentrations in adults.

Methods

The review was registered in the International Prospective Systematic Review (PROSPERO, CRD42023471163). The Cochrane Library, PubMed, and Web of Science databases were searched for studies through July 2023. Studies that assessed the effects of exercise training on FGF21 concentration in adults were included. The random effect model, data with standardized mean difference (SMD), and 95% confidence intervals (CI) were used to evaluate the pooled effect size of exercise training on FGF21. The risk of heterogeneity and bias were evaluated. A total of 12 studies involving 401 participants were included.

Results

The total effect size was 0.3 (95% CI [-0.3-0.89], p = 0.33) when comparing participants who exercised to those who were sedentary. However, subgroup analysis indicated that concurrent exercise and a duration ≥10 weeks significantly decreased FGF21 concentrations with an effect size of -0.38 (95% CI [-0.74--0.01], p < 0.05) and -0.38 (95% CI [-0.63--0.13], p < 0.01), respectively.

Conclusion

Concurrent exercise and longer duration may be more efficient way to decrease FGF21 concentrations in adults with metabolic disorder.

Efficacy and safety of aldafermin in non-alcoholic steatohepatitis: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is an advanced subtype of non-alcoholic fatty liver disease (NAFLD). NASH prevalence is increasing exponentially and carries a high risk for disease progression, cirrhosis, and liver-related mortality. Aldafermin, a fibroblast growth factor 19 (FGF19) analog, is one of the evolving therapeutic agents with the potential to regulate multiple pathways involved in the pathogenesis of NASH. We aimed to investigate the efficacy and safety of aldafermin in patients with NASH.

METHODS

PubMed, Scopus, Cochrane Library, and Web of Science were searched till November 2023 to identify eligible randomized controlled trials (RCTs). Continuous data were pooled as mean difference (MD), while dichotomous data were pooled as risk ratios (RR) with a 95 % confidence interval. A subgroup meta-analysis was conducted to evaluate the efficacy of the two doses (1 mg and 3 mg) of aldafermin.

RESULTS

Four RCTs with a total of 491 patients were included. Aldafermin showed a dose-dependent improvement in the ≥30 % reduction in the liver fat content (RR: 2.16, 95 % CI [1.41 to 3.32]) and (RR: 5.00, 95 % CI [1.34 to 18.64]), alanine aminotransferase levels (MD: -19.79, 95 % CI [-30.28 to -9.3]) and (MD: -21.91, 95 % CI [-29.62 to -14.21]), aspartate aminotransferase levels (MD: -11.79, 95 % CI [-18.06 to -5.51]) and (MD: -13.9, 95 % CI [-18.59 to -9.21]), and enhanced liver fibrosis score (ELF) (MD: -0.13, 95 % CI [-0.29 to 0.02]) and (MD: -0.33, 95 % CI [-0.50 to -0.17]), in the 1 mg and 3 mg subgroups respectively. No significant differences were detected in the aldafermin group regarding histologic endpoints, lipid profile, metabolic parameters, and overall adverse effects, except for the increased occurrence of diarrhea in the aldafermin 3 mg subgroup.

CONCLUSION

Aldafermin is a promising well-tolerated therapeutic agent for NASH with evidence supporting its ability to reduce liver fat content, fibrosis serum biomarkers, and liver enzymes. However, its effectiveness in improving histologic fibrosis, while showing numerical trends, still lacks statistical significance. Larger and longer NASH trials are warranted to enhance the robustness of the evidence.

Metabolic Dysfunction-Associated Steatotic Liver Disease: From Pathogenesis to Current Therapeutic Options

The epidemiological burden of liver steatosis associated with metabolic diseases is continuously growing worldwide and in all age classes. This condition generates possible progression of liver damage (i.e., inflammation, fibrosis, cirrhosis, hepatocellular carcinoma) but also independently increases the risk of cardio-metabolic diseases and cancer. In recent years, the terminological evolution from "nonalcoholic fatty liver disease" (NAFLD) to "metabolic dysfunction-associated fatty liver disease" (MAFLD) and, finally, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been paralleled by increased knowledge of mechanisms linking local (i.e., hepatic) and systemic pathogenic pathways. As a consequence, the need for an appropriate classification of individual phenotypes has been oriented to the investigation of innovative therapeutic tools. Besides the well-known role for lifestyle change, a number of pharmacological approaches have been explored, ranging from antidiabetic drugs to agonists acting on the gut-liver axis and at a systemic level (mainly farnesoid X receptor (FXR) agonists, PPAR agonists, thyroid hormone receptor agonists), anti-fibrotic and anti-inflammatory agents. The intrinsically complex pathophysiological history of MASLD makes the selection of a single effective treatment a major challenge, so far. In this evolving scenario, the cooperation between different stakeholders (including subjects at risk, health professionals, and pharmaceutical industries) could significantly improve the management of disease and the implementation of primary and secondary prevention measures. The high healthcare burden associated with MASLD makes the search for new, effective, and safe drugs a major pressing need, together with an accurate characterization of individual phenotypes. Recent and promising advances indicate that we may soon enter the era of precise and personalized therapy for MASLD/MASH.

Pegbelfermin for reducing transaminase levels in patients with non-alcoholic steatohepatitis: a dose-response meta-analysis of randomized controlled trials

Background

The efficacy of Pegbelfermin (PGBF) in treating non-alcoholic steatohepatitis (NASH) remains controversial. Therefore, we conducted a dose-response meta-analysis to explore the effect and pattern of PGBF at different dosages and treatment durations on transaminase reduction in NASH patients.

Methods

We conducted searches on PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov, and supplemented the search with gray literature and manual searches. Randomized controlled trials (RCTs) evaluating the efficacy of PGBF in NASH patients were included. Risk of bias was assessed by Cochrane Risk of Bias Tool 2.0. We used random-effects models, generalized least squares regression, constrained maximum likelihood, and restricted cubic splines to explore the dose-response relationship. Egger's linear regression was employed to assess publication bias. The study is registered with PROSPERO, CRD42023448024.

Results

Four RCT studies from the period 2018-2023, involving 546 participants, were included. No participants discontinued PGBF treatment due to adverse events. High-dose PGBF treatment significantly reduced transaminase levels in NASH patients compared to the low-dose group (ALT %: MD = 14.94, 95% CI = 2.11-27.77; AST %: MD = 9.05, 95% CI = 3.17-14.92). Longer treatment duration further decreased transaminase levels (ALT%: MD = 8.81, 95% CI = 4.07-13.56; AST%: MD = 6.72, 95% CI = 2.62-10.81). Egger's test did not reveal significant publication bias (p > 0.05). Further investigation indicated a ceiling effect of PGBF dosage on transaminase reduction at 30 mg/week, and NASH patients experienced a rebound in transaminase levels after 28 weeks of continuous treatment.

Conclusion

There is a positive correlation between PGBF dosage and transaminase reduction within a certain range, showing an overall non-linear dose-response relationship. This finding provides guidance for the clinical application of PGBF. Clinicians should be mindful of the dosage ceiling at 30 mg/week and monitor changes in transaminase levels after 28 weeks for timely adjustments in PGBF dosage.

Systematic review registration

PROSPERO, CRD42023448024. https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=448024.

Drug targets regulate systemic metabolism and provide new horizons to treat nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), is the advanced stage of nonalcoholic fatty liver disease (NAFLD) with rapidly rising global prevalence. It is featured with severe hepatocyte apoptosis, inflammation and hepatic lipogenesis. The drugs directly targeting the processes of steatosis, inflammation and fibrosis are currently under clinical investigation. Nevertheless, the long-term ineffectiveness and remarkable adverse effects are well documented, and new concepts are required to tackle with the root causes of NASH progression. We critically assess the recently validated drug targets that regulate the systemic metabolism to ameliorate NASH. Thermogenesis promoted by mitochondrial uncouplers restores systemic energy expenditure. Furthermore, regulation of mitochondrial proteases and proteins that are pivotal for intracellular metabolic homeostasis normalize mitochondrial function. Secreted proteins also improve systemic metabolism, and NASH is ameliorated by agonizing receptors of secreted proteins with small molecules. We analyze the drug design, the advantages and shortcomings of these novel drug candidates. Meanwhile, the structural modification of current NASH therapeutics significantly increased their selectivity, efficacy and safety. Furthermore, the arising CRISPR-Cas9 screen strategy on liver organoids has enabled the identification of new genes that mediate lipid metabolism, which may serve as promising drug targets. In summary, this article discusses the in-depth novel mechanisms and the multidisciplinary approaches, and they provide new horizons to treat NASH.

Targeting the FGF19-FGFR4 pathway for cholestatic, metabolic, and cancerous diseases

Human fibroblast growth factor 19 (FGF19, or FGF15 in rodents) plays a central role in controlling bile acid (BA) synthesis through a negative feedback mechanism. This process involves a postprandial crosstalk between the BA-activated ileal farnesoid X receptor and the hepatic Klotho beta (KLB) coreceptor complexed with fibrobalst growth factor receptor 4 (FGFR4) kinase. Additionally, FGF19 regulates glucose, lipid, and energy metabolism by coordinating responses from functional KLB and FGFR1-3 receptor complexes on the periphery. Pharmacologically, native FGF19 or its analogs decrease elevated BA levels, fat content, and collateral tissue damage. This makes them effective in treating both cholestatic diseases such as primary biliary or sclerosing cholangitis (PBC or PSC) and metabolic abnormalities such as nonalcoholic steatohepatitis (NASH). However, chronic administration of FGF19 drives oncogenesis in mice by activating the FGFR4-dependent mitogenic or hepatic regenerative pathway, which could be a concern in humans. Agents that block FGF19 or FGFR4 signaling have shown great potency in preventing FGF19-responsive hepatocellular carcinoma (HCC) development in animal models. Recent phase 1/2 clinical trials have demonstrated promising results for several FGF19-based agents in selectively treating patients with PBC, PSC, NASH, or HCC. This review aims to provide an update on the clinical development of both analogs and antagonists targeting the FGF19-FGFR4 signaling pathway for patients with cholestatic, metabolic, and cancer diseases. We will also analyze potential safety and mechanistic concerns that should guide future research and advanced trials.

Association of metabolic-dysfunction associated steatotic liver disease with polycystic ovary syndrome

Non-alcoholic fatty liver disease (NAFLD), which has a prevalence of over 25% in adults, encompasses a wide spectrum of liver diseases. Metabolic-dysfunction associated steatotic liver disease (MASLD), the new term for NAFLD, is characterized by steatotic liver disease accompanied by cardiometabolic criteria, showing a strong correlation with metabolic diseases. Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease affecting 4-21% of women of reproductive age. Numerous studies have indicated that NAFLD and PCOS often occur together. However, as MASLD is a new term, there is still a lack of reports describing the effects of MASLD on the development of PCOS. In this review article, we have summarized the complex and multifaceted connections between MASLD and PCOS. Understanding the pathogenesis and treatment methods could not only guide the clinical prevention, diagnosis, and treatment of PCOS in patients with MASLD, but also increase the clinical attention of reproductive doctors to MASLD.

New Therapeutic Approaches for the Treatment of Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) and Increased Cardiovascular Risk

Metabolic dysfunction-associated steatotic liver disease (MASLD) was previously known as nonalcoholic fatty liver disease (NAFLD). The main characteristic of the disease is the process of long-term liver inflammation, which leads to hepatocyte damage followed by liver fibrosis and eventually cirrhosis. Additionally, these patients are at a greater risk for developing cardiovascular diseases (CVD). They have several pathophysiological mechanisms in common, primarily lipid metabolism disorders and lipotoxicity. Lipotoxicity is a factor that leads to the occurrence of heart disease and the occurrence and progression of atherosclerosis. Atherosclerosis, as a multifactorial disease, is one of the predominant risk factors for the development of ischemic heart disease. Therefore, CVD are one of the most significant carriers of mortality in patients with metabolic syndrome. So far, no pharmacotherapy has been established for the treatment of MASLD, but patients are advised to reduce their body weight and change their lifestyle. In recent years, several trials of different drugs, whose basic therapeutic indications include other diseases, have been conducted. Because it has been concluded that they can have beneficial effects in the treatment of these conditions as well, in this paper, the most significant results of these studies will be presented.

Pegbelfermin in Patients With Nonalcoholic Steatohepatitis and Compensated Cirrhosis (FALCON 2): A Randomized Phase 2b Study

BACKGROUND & AIMS

Pegbelfermin is a polyethylene glycol-conjugated analog of human fibroblast growth factor 21, a nonmitogenic hormone that regulates energy metabolism. This phase 2b study evaluated 48-week pegbelfermin treatment in patients with nonalcoholic steatohepatitis (NASH) with compensated cirrhosis.

METHODS

FALCON 2 (NCT03486912) was a randomized (1:1:1:1), double-blind, placebo-controlled study. Eligible adults had biopsy-confirmed NASH and stage 4 fibrosis. Pegbelfermin (10, 20, or 40 mg) or placebo was injected subcutaneously once weekly. The primary endpoint was 1 or more stages of improvement in the NASH Clinical Research Network fibrosis score without NASH worsening at week 48; pegbelfermin dose response was assessed using a Cochran-Armitage trend test across proportions (1-sided α = .05). Additional endpoints included histologic and noninvasive measures of steatosis, fibrosis, and liver injury/inflammation.

RESULTS

Overall, 155 patients were randomized, and 154 patients received treatment. At week 48, 24% to 28% of the pegbelfermin arms had primary endpoint responses vs 31% of the placebo arm (P = .361). Nonalcoholic fatty liver disease activity score improvements were more frequent with pegbelfermin vs placebo and were driven primarily by reduced lobular inflammation. Numerically higher proportions of the pegbelfermin arms had liver stiffness (magnetic resonance elastography) and steatosis (magnetic resonance imaging-proton density fat fraction) improvements vs placebo; these differences were not statistically significant. Mean N-terminal type III collagen propeptide, alanine aminotransferase, and aspartate aminotransferase values were numerically lower in the 20- and/or 40-mg pegbelfermin arms compared with placebo. Serious adverse events were more frequent with pegbelfermin vs placebo, although none were treatment related. One patient (40-mg pegbelfermin) discontinued treatment because of a treatment-emergent adverse event (worsening ascites).

CONCLUSIONS

FALCON 2 did not meet its primary endpoint of 1 or more stages of improvement in the NASH Clinical Research Network fibrosis without NASH worsening assessed via biopsy. Pegbelfermin generally was well tolerated in this advanced NASH population.

Pegbelfermin in Patients With Nonalcoholic Steatohepatitis and Stage 3 Fibrosis (FALCON 1): A Randomized Phase 2b Study

BACKGROUND & AIMS

Pegbelfermin is a polyethlene glycol-conjugated analog of human fibroblast growth factor 21, a nonmitogenic hormone that regulates energy metabolism. This phase 2b study evaluated 48-week pegbelfermin treatment in patients with nonalcoholic steatohepatitis (NASH) and stage 3 (bridging) fibrosis.

METHODS

The FALCON 1 study (NCT03486899) was a multicenter, randomized (1:1:1:1), double-blind, placebo-controlled study. Patients with biopsy-confirmed NASH and stage 3 fibrosis (N = 197) received weekly subcutaneous pegbelfermin (10, 20, or 40 mg) or placebo injections for 48 weeks. The week 24 primary endpoint was a ≥1-point decrease in fibrosis score without NASH worsening or NASH improvement without fibrosis worsening; pegbelfermin dose response was assessed using a Cochran-Armitage trend test across proportions (1-sided α = 0.05). Secondary/exploratory endpoints included histological and noninvasive measures of steatosis, fibrosis, and liver injury/inflammation.

RESULTS

At week 24, the primary endpoint was met by 14% (placebo) vs 24%-31% (pegbelfermin arms); statistical significance was not reached due to lack of pegbelfermin dose response (P = .134). At weeks 24 and 48, more patients who received pegbelfermin had ≥30% relative reductions in hepatic fat fraction (magnetic resonance imaging-proton density fat fraction) vs placebo, although no differences reached statistical significance. In the pegbelfermin arms, improvements in liver fibrosis (magnetic resonance elastography and N-terminal type III collagen propeptide) and liver injury/inflammation (alanine aminotransferase, aspartate aminotransferase) were observed vs placebo. Adverse events occurred at similar frequencies across arms. No treatment-related serious adverse events were observed.

CONCLUSIONS

The FALCON 1 study did not meet its primary endpoint; a ≥1-point decrease in fibrosis score without NASH worsening or NASH improvement without fibrosis worsening assessed via biopsy. Pegbelfermin was generally well tolerated during 48 weeks of treatment.

Gut liver brain axis in diseases: the implications for therapeutic interventions

Gut-liver-brain axis is a three-way highway of information interaction system among the gastrointestinal tract, liver, and nervous systems. In the past few decades, breakthrough progress has been made in the gut liver brain axis, mainly through understanding its formation mechanism and increasing treatment strategies. In this review, we discuss various complex networks including barrier permeability, gut hormones, gut microbial metabolites, vagus nerve, neurotransmitters, immunity, brain toxic metabolites, β-amyloid (Aβ) metabolism, and epigenetic regulation in the gut-liver-brain axis. Some therapies containing antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), polyphenols, low FODMAP diet and nanotechnology application regulate the gut liver brain axis. Besides, some special treatments targeting gut-liver axis include farnesoid X receptor (FXR) agonists, takeda G protein-coupled receptor 5 (TGR5) agonists, glucagon-like peptide-1 (GLP-1) receptor antagonists and fibroblast growth factor 19 (FGF19) analogs. Targeting gut-brain axis embraces cognitive behavioral therapy (CBT), antidepressants and tryptophan metabolism-related therapies. Targeting liver-brain axis contains epigenetic regulation and Aβ metabolism-related therapies. In the future, a better understanding of gut-liver-brain axis interactions will promote the development of novel preventative strategies and the discovery of precise therapeutic targets in multiple diseases.

Molecular Aspects of MAFLD-New Insights on Pathogenesis and Treatment

Metabolic-associated liver disease (MAFLD) affects up to 70% of overweight and more than 90% of morbidly obese people, and its pathogenesis is rather complex and multifactorial. The criteria for MAFLD include the presence of hepatic steatosis in addition to one of the following three criteria: overweight or obesity, presence of type 2 diabetes mellitus (T2DM), or evidence of metabolic dysregulation. If the specific criteria are present, the diagnosis of MAFLD can be made regardless of alcohol consumption and previous liver disease. The pathophysiological mechanisms of MAFLD, including inflammation, lipotoxicity, mitochondrial disfunction, and oxidative stress, as well as the impact of intestinal gut microbiota, are constantly being elucidated. Treatment strategies that are continually emerging are based on different key points in MAFLD pathogenesis. Yet, the ideal therapeutic option has still not been found and future research is of great importance, as MAFLD represents a multisystemic disease with numerous complications.

Metabolic dysfunction-associated fatty liver disease (MAFLD): an update of the recent advances in pharmacological treatment

Metabolic dysfunction-associated fatty liver disease (MAFLD) is nowadays considered the liver manifestation of metabolic syndrome. Its prevalence is increasing worldwide in parallel to the epidemic of diabetes and obesity. MAFLD includes a wide spectrum of liver injury including simple steatosis and non-alcoholic steatohepatitis (NASH) that may lead to serious complications such as liver cirrhosis and liver cancer. The complexity of its pathophysiology and the intricate mechanisms underlying disease progression explains the huge variety of molecules targeting diverse biological mechanisms that have been tested in preclinical and clinical settings in the last two decades. Thanks to the large number of clinical trials of the last few years, most of them still ongoing, the pharmacotherapy scenario of MAFLD is rapidly evolving. The three major components of MAFLD, steatosis, inflammation, and fibrosis seem to be safely targeted with different agents at least in a large proportion of patients. Likely, in the next few years more than one drug will be approved for the treatment of MAFLD at different disease stages. The aim of this review is to synthesize the characteristics and the results of the most advanced clinical trials for the treatment of NASH to evaluate the recent advances of pharmacotherapy in this disease.

A new FGF15/19-mediated gut-to-heart axis controls cardiac hypertrophy

FGF15 and its human orthologue, FGF19, are members of the endocrine FGF family and are secreted by ileal enterocytes in response to bile acids. FGF15/19 mainly targets the liver, but recent studies indicate that it also regulates skeletal muscle mass and adipose tissue plasticity. The aim of this study was to determine the role(s) of the enterokine FGF15/19 during the development of cardiac hypertrophy. Studies in a cohort of humans suffering from heart failure showed increased circulating levels of FGF19 compared with control individuals. We found that mice lacking FGF15 did not develop cardiac hypertrophy in response to three different pathophysiological stimuli (high-fat diet, isoproterenol, or cold exposure). The heart weight/tibia length ratio and the cardiomyocyte area (as measures of cardiac hypertrophy development) under hypertrophy-inducing conditions were lower in Fgf15-null mice than in wild-type mice, whereas the levels of the cardiac damage marker atrial natriuretic factor (Nppa) were up-regulated. Echocardiographic measurements showed similar results. Moreover, the genes involved in fatty acid metabolism were down-regulated in Fgf15-null mice. Conversely, experimental increases in FGF15 induced cardiac hypertrophy in vivo, without changes in Nppa and up-regulation of metabolic genes. Finally, in vitro studies using cardiomyocytes showed that FGF19 had a direct effect on these cells promoting hypertrophy. We have identified herein an inter-organ signaling pathway that runs from the gut to the heart, acts through the enterokine FGF15/19, and is involved in cardiac hypertrophy development and regulation of fatty acid metabolism in the myocardium. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Immune microenvironment changes of liver cirrhosis: emerging role of mesenchymal stromal cells

Cirrhosis is a progressive and diffuse liver disease characterized by liver tissue fibrosis and impaired liver function. This condition is brought about by several factors, including chronic hepatitis, hepatic steatosis, alcohol abuse, and other immunological injuries. The pathogenesis of liver cirrhosis is a complex process that involves the interaction of various immune cells and cytokines, which work together to create the hepatic homeostasis imbalance in the liver. Some studies have indicated that alterations in the immune microenvironment of liver cirrhosis are closely linked to the development and prognosis of the disease. The noteworthy function of mesenchymal stem cells and their paracrine secretion lies in their ability to promote the production of cytokines, which in turn enhance the self-repairing capabilities of tissues. The objective of this review is to provide a summary of the alterations in liver homeostasis and to discuss intercellular communication within the organ. Recent research on MSCs is yielding a blueprint for cell typing and biomarker immunoregulation. Hopefully, as MSCs researches continue to progress, novel therapeutic approaches will emerge to address cirrhosis.

Studying sex differences in responses to fibroblast growth factor 21 administration in obese mice consuming a sweet-fat diet

In animals, obesity caused by consumption of a sweet-fat diet (SFD) is the most adequate mouse model of human diet-induced obesity. Fibroblast growth factor 21 (FGF21) reduces body weight, beneficially affects taste preferences, and corrects glucose metabolism in obese mice. Sex is known to influence FGF21 effects in different models of diet-induced and hereditary obesity. In mice with SFD-induced obesity, the effects of FGF21 have been studied only in males. The aim of this study was to compare the effects of FGF21 on body weight, food preferences and glucose and lipid metabolism in C57Bl/6J male and female mice with SFD-induced obesity. Mice were fed with a diet consisting of standard chow, lard and cookies for 10 weeks, then they were injected with FGF21 (1 mg per 1 kg) or vehicle for 7 days. Body weight, weights of different types of food, blood parameters, glucose tolerance, gene and protein expression in the liver, gene expression in the white, brown adipose tissues, and the hypothalamus were assessed. FGF21 administration reduced body weight, did not alter total energy consumption, and activated orexigenic pathways of hypothalamus in mice of both sexes. However, sex dimorphism was found in the realization of the orexigenic FGF21 action at the transcriptional level in the hypothalamus. Metabolic effects of FGF21 were also sex-specific. Only in males, FGF21 exerted beneficial antidiabetic action: it reduced fatty acid and leptin plasma levels, improved glucose-tolerance, and upregulated hepatic expression of Ppargc1, Fasn, Accα, involved in lipid turnover, gene Insr and protein glucokinase, involved in insulin action. Only in obese females, FGF21 induced preference of standard diet to sweet food. Thus, in mouse model of obesity induced by consumption of a sweet-fat diet, the catabolic effect of FGF21 was not sex-specific and hormonal, transcriptional and behavioral effects of FGF21 were sex-specific. These data suggest elaboration of different approaches to use FGF21 analogs for correction of metabolic consequences of obesity in different sexes.

Toxicokinetics of recombinant human fibroblast growth factor 21 for injection in cynomolgus monkey for 3 months

Introduction: Recombinant human fibroblast growth factor 21 (FGF-21) is a potential therapeutic agent for multiple metabolic diseases. However, little is known about the toxicokinetic characteristics of FGF-21. Methods: In the present study, we investigated the toxicokinetics of FGF-21 delivered via subcutaneous injection in vivo. Twenty cynomolgus monkeys were injected subcutaneously with different doses of FGF-21 for 86 days. Serum samples were collected at eight different time points (0, 0.5, 1.5, 3, 5, 8, 12, and 24 h) on day 1, 37 and 86 for toxicokinetic analysis. The serum concentrations of FGF-21 were measured using a double sandwich Enzyme-linked immunosorbent assay. Blood samples were collected on day 0, 30, 65, and 87 for blood and blood biochemical tests. Necropsy and pathological analysis were performed on d87 and d116 (after recovery for 29 days). Results: The average AUC_(0-24h) values of low-dose FGF-21 on d1, d37, and d86 were 5253, 25268, and 60445 μg h/L, and the average AUC_(0-24h) values of high-dose FGF-21 on d1, d37, and d86 were 19964, 78999, and 1952821 μg h/L, respectively. Analysis of the blood and blood biochemical indexes showed that prothrombin time and AST content in the high-dose FGF-21 group increased. However, no significant changes in other blood and blood biochemical indexes were observed. The anatomical and pathological results showed that continuous subcutaneous injection of FGF-21 for 86 days did not affect organ weight, the organ coefficient, and histopathology in cynomolgus monkeys. Discussion: Our results have guiding significance for the preclinical research and clinical use of FGF-21.

Crosstalk between Gut Microbiota and Bile Acids in Cholestatic Liver Disease

Emerging evidence suggests the complex interactions between gut microbiota and bile acids, which are crucial end products of cholesterol metabolism. Cholestatic liver disease is characterized by dysfunction of bile production, secretion, and excretion, as well as excessive accumulation of potentially toxic bile acids. Given the importance of bile acid homeostasis, the complex mechanism of the bile acid-microbial network in cholestatic liver disease requires a thorough understanding. It is urgent to summarize the recent research progress in this field. In this review, we highlight how gut microbiota regulates bile acid metabolism, how bile acid pool shapes the bacterial community, and how their interactions contribute to the pathogenesis of cholestatic liver disease. These advances might provide a novel perspective for the development of potential therapeutic strategies that target the bile acid pathway.

Biological and pharmacological functions of the FGF19- and FGF21-coreceptor beta klotho

Beta klotho (KLB) is a fundamental component in fibroblast growth factor receptor (FGFR) signaling as it serves as an obligatory coreceptor for the endocrine hormones fibroblast growth factor 19 (FGF19) and fibroblast growth factor 21 (FGF21). Through the development of FGF19- and FGF21 mimetics, KLB has emerged as a promising drug target for treating various metabolic diseases, such as type 2 diabetes (T2D), non-alcoholic fatty liver disease (NAFLD), and cardiovascular disease. While rodent studies have significantly increased our understanding of KLB function, current clinical trials that test the safety and efficacy of KLB-targeting drugs raise many new scientific questions about human KLB biology. Although most KLB-targeting drugs can modulate disease activity in humans, individual patient responses differ substantially. In addition, species-specific differences in KLB tissue distribution may explain why the glucose-lowering effects that were observed in preclinical studies are not fully replicated in clinical trials. Besides, the long-term efficacy of KLB-targeting drugs might be limited by various pathophysiological conditions known to reduce the expression of KLB. Moreover, FGF19/FGF21 administration in humans is also associated with gastrointestinal side effects, which are currently unexplained. A better understanding of human KLB biology could help to improve the efficacy and safety of existing or novel KLB/FGFR-targeting drugs. In this review, we provide a comprehensive overview of the current understanding of KLB biology, including genetic variants and their phenotypic associations, transcriptional regulation, protein structure, tissue distribution, subcellular localization, and function. In addition, we will highlight recent developments regarding the safety and efficacy of KLB-targeting drugs in clinical trials. These insights may direct the development and testing of existing and future KLB-targeting drugs.

FGF19 improves sevoflurane-induced cognitive dysfunction in rats through the PGC-1α/BDNF/FNDC5 pathway

Postoperative cognitive dysfunction (POCD) is a serious central nervous system complication characterized by impaired memory, reduced information processing ability, and anxiety. Recently, the role of FGF19 in neurological diseases has been reported. However, the effect and mechanisms of FGF19 in improving symptoms of POCD remain unknown. This study aimed to identify the role and exploring the underlying mechanisms of FGF19 in POCD. Here, rats were separated into four different groups, including control, sevoflurane (sev), sev + AAV-empty, and sev + AAV-FGF19 group. Then, the Morris water maze (MWM) test was applied to identify the effect of FGF19 on POCD rats. The result proved that FGF19 improved sevoflurane induced cognitive dysfunction in rats. Subsequently, the expressions of TNF-α, IL-6, IL-1β, and IL-10 were detected to verify the anti-neuroinflammatory effects of FGF19 in POCD rats. Furthermore, DHE fluorescent staining assay showed that FGF19 could inhibit sevoflurane-induced oxidative stress in POCD rats. Besides, NISSL staining and TUNEL assay were applied to reveal that FGF19 could alleviate hippocampal neuron injury induced by sevoflurane in rats. Moreover, mechanistic studies confirmed that FGF19 improved symptoms of POCD by mediated PGC-1α/BDNF/FNDC5 pathway. Together, these results suggested that FGF19 improves sevoflurane-induced POCD in rats through the PGC-1α/BDNF/FNDC5 pathway.

Fibroblast growth factor-21 (FGF21) analogs as possible treatment options for diabetes mellitus in veterinary patients

Fibroblast growth factors (FGFs) are involved in numerous metabolic processes. The endocrine subfamily of FGFs, consisting of FGF19, FGF21, and FGF23, might have beneficial effects in the treatment of diabetes mellitus (DM) and/or obesity. The analog with the greatest potential, FGF21, lowers blood glucose levels, improves insulin sensitivity, and induces weight loss in several animal models. In this review we summarize recent (pre)clinical findings with FGF21 analogs in animal models and men. Furthermore, possible applications of FGF21 analogs for pets with DM will be discussed. As currently, information about the use of FGF21 analogs in pet animals is scarce.

Effect of pegbelfermin on NASH and fibrosis-related biomarkers and correlation with histological response in the FALCON 1 trial

Background & Aims

FALCON 1 was a phase IIb study of pegbelfermin in patients with non-alcoholic steatohepatitis (NASH) and stage 3 fibrosis. This FALCON 1 post hoc analysis aimed to further assess the effect of pegbelfermin on NASH-related biomarkers, correlations between histological assessments and non-invasive biomarkers, and concordance between the week 24 histologically assessed primary endpoint response and biomarkers.

Methods

Blood-based composite fibrosis scores, blood-based biomarkers, and imaging biomarkers were evaluated for patients with available data from FALCON 1 at baseline through week 24. SomaSignal tests assessed protein signatures of NASH steatosis, inflammation, ballooning, and fibrosis in blood. Linear mixed-effect models were fit for each biomarker. Correlations and concordance were assessed between blood-based biomarkers, imaging, and histological metrics.

Results

At week 24, pegbelfermin significantly improved blood-based composite fibrosis scores (ELF, FIB-4, APRI), fibrogenesis biomarkers (PRO-C3 and PC3X), adiponectin, CK-18, hepatic fat fraction measured by MRI-proton density fat fraction, and all four SomaSignal NASH component tests. Correlation analyses between histological and non-invasive measures identified four main categories: steatosis/metabolism, tissue injury, fibrosis, and biopsy-based metrics. Concordant and discordant effects of pegbelfermin on the primary endpoint vs. biomarker responses were observed; the most clear and concordant effects were on measures of liver steatosis and metabolism. A significant association between hepatic fat measured histologically and by imaging was observed in pegbelfermin arms.

Conclusions

Pegbelfermin improved NASH-related biomarkers most consistently through improvement of liver steatosis, though biomarkers of tissue injury/inflammation and fibrosis were also improved. Concordance analysis shows that non-invasive assessments of NASH support and exceed the improvements detected by liver biopsy, suggesting that greater consideration should be given to the totality of available data when evaluating the efficacy of NASH therapeutics.

Clinical trial number

Post hoc analysis of NCT03486899.

Impact and implications

FALCON 1 was a study of pegbelfermin vs. placebo in patients with non-alcoholic steatohepatitis (NASH) without cirrhosis; in this study, patients who responded to pegbelfermin treatment were identified through examination of liver fibrosis in tissue samples collected through biopsy. In the current analysis, non-invasive blood- and imaging-based measures of fibrosis, liver fat, and liver injury were used to determine pegbelfermin treatment response to see how they compared with the biopsy-based results. We found that many of the non-invasive tests, particularly those that measured liver fat, identified patients who responded to pegbelfermin treatment, consistent with the liver biopsy findings. These results suggest that there may be additional value in using data from non-invasive tests, along with liver biopsy, to evaluate how well patients with NASH respond to treatment.

Advances in FGFs for diabetes care applications

BACKGROUND

Diabetes mellitus (DM) is an endocrine and metabolic disease caused by a variety of pathogenic factors, including genetic factors, environmental factors and behavior. In recent decades, the number of cases and the prevalence of diabetes have steadily increased, and it has become one of the most threatening diseases to human health in the world. Currently, insulin is the most effective and direct way to control hyperglycemia for diabetes treatment at a low cost. However, hypoglycemia is often a common complication of insulin treatment. Moreover, with the extension of treatment time, insulin resistance, considered the typical adverse symptom, can appear. Therefore, it is urgent to develop new targets and more effective and safer drugs for diabetes treatment to avoid adverse reactions and the insulin tolerance of traditional hypoglycemic drugs.

SCOPE OF REVIEW

In recent years, it has been found that some fibroblast growth factors (FGFs), including FGF1, FGF19 and FGF21, can safely and effectively reduce hyperglycemia and have the potential to be developed as new drugs for the treatment of diabetes. FGF23 is also closely related to diabetes and its complications, which provides a new approach for regulating blood glucose and solving the problem of insulin tolerance.

MAJOR CONCLUSIONS

This article reviews the research progress on the physiology and pharmacology of fibroblast growth factor in the treatment of diabetes. We focus on the application of FGFs in diabetes care and prevention.

Comprehensive molecular mechanisms and clinical therapy in nonalcoholic steatohepatitis: An overview and current perspectives

Our understanding of nonalcoholic steatohepatitis (NASH) pathophysiology continues to advance rapidly. Given the complexity of the pathogenesis of NASH, the field has moved from describing the single pathogenesis of NASH to deeply phenotyping with a description of the multi-mechanism and multi-target pathogenesis that includes glucose, lipid and cholesterol metabolism, fibrotic progression, inflammation, immune reaction and apoptosis. To make the picture more complex, the pathogenesis of NASH involves pathological connections between the liver and several organs such as the adipose, pancreas, kidney and gut. Numerous pharmacologic candidates have been tested in clinical trials and have generated some positive results. Importantly, PPAR as triglyceride synthesis inhibitor and FXR as bile acids synthesis inhibitor have displayed beneficial effects on candidates for lipid and cholesterol metabolism. Although the efficacy of these drugs has been affirmed, serious side effects hinder their further development. It is a particularly important task to carry out the in-depth long-term research. Additionally, drug combination increases response rate and reduces side effects of a single drug. Mastering the advantages and limitations of clinical candidate drugs and continuous improvement and innovation are necessary to formulate a new strategy for the future treatment of NASH.

A new perspective on NAFLD: Focusing on the crosstalk between peroxisome proliferator-activated receptor alpha (PPARα) and farnesoid X receptor (FXR)

Nonalcoholic fatty liver disease (NAFLD) is primarily caused by abnormal lipid metabolism and the accumulation of triglycerides in the liver. NAFLD is also associated with hepatic steatosis and nutritional and energy imbalances and is a chronic liver disease associated with a number of factors. Nuclear receptors play a key role in balancing energy and nutrient metabolism, and the peroxisome proliferator-activated receptor alpha (PPARα) and farnesoid X receptor (FXR) regulate lipid metabolism genes, controlling hepatocyte lipid utilization and regulating bile acid (BA) synthesis and transport. They play an important role in lipid metabolism and BA homeostasis. At present, PPARα and FXR are the most promising targets for the treatment of NAFLD among nuclear receptors. This review focuses on the crosstalk mechanisms and transcriptional regulation of PPARα and FXR in the pathogenesis of NAFLD and summarizes PPARα and FXR drugs in clinical trials, laying a theoretical foundation for the targeted treatment of NAFLD and the development of novel therapeutic strategies.

ERα-Dependent Regulation of Adropin Predicts Sex Differences in Liver Homeostasis during High-Fat Diet

Non-alcoholic fatty liver disease (NAFLD) represents a public health issue, due to its prevalence and association with other cardiometabolic diseases. Growing evidence suggests that NAFLD alters the production of hepatokines, which, in turn, influence several metabolic processes. Despite accumulating evidence on the major role of estrogen signaling in the sexually dimorphic nature of NAFLD, dependency of hepatokine expression on sex and estrogens has been poorly investigated. Through in vitro and in vivo analysis, we determined the extent to which hepatokines, known to be altered in NAFLD, can be regulated, in a sex-specific fashion, under different hormonal and nutritional conditions. Our study identified four hepatokines that better recapitulate sex and estrogen dependency. Among them, adropin resulted as one that displays a sex-specific and estrogen receptor alpha (ERα)-dependent regulation in the liver of mice under an excess of dietary lipids (high-fat diet, HFD). Under HFD conditions, the hepatic induction of adropin negatively correlates with the expression of lipogenic genes and with fatty liver in female mice, an effect that depends upon hepatic ERα. Our findings support the idea that ERα-mediated induction of adropin might represent a potential approach to limit or prevent NAFLD.

Hepatocyte-Secreted Autotaxin Exacerbates Nonalcoholic Fatty Liver Disease Through Autocrine Inhibition of the PPARα/FGF21 Axis

BACKGROUND & AIMS

The prevalence of nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions globally as a result of the rapid increase in obesity. However, there is no Food and Drug Administration-approved pharmacotherapy available for NAFLD. This study investigated the role of autotaxin, a secreted enzyme that hydrolyzes lysophosphatidylcholine to produce lysophosphatidic acid (LPA), in the pathogenesis of NAFLD and to explore whether genetic or pharmacologic interventions targeting autotaxin ameliorate NAFLD.

METHODS

The clinical association of autotaxin with the severity of NAFLD was analyzed in 125 liver biopsy-proven NAFLD patients. C57BL/6N mice or fibroblast growth factor 21 (FGF21)-null mice were fed a high-fat diet or a choline-deficient diet to investigate the role of the autotaxin-FGF21 axis in NAFLD development by hepatic knockdown and antibody neutralization. Huh7 cells were used to investigate the autocrine effects of autotaxin.

RESULTS

Serum autotaxin levels were associated positively with histologic scores and NAFLD severity. Hepatocytes, but not adipocytes, were the major contributor to increased circulating autotaxin in both patients and mouse models with NAFLD. In mice, knocking-down hepatic autotaxin or treatment with a neutralizing antibody against autotaxin significantly reduced high-fat diet-induced NAFLD and high fat- and choline-deficient diet-induced nonalcoholic steatohepatitis and fibrosis, accompanied by a marked increase of serum FGF21. Mechanistically, autotaxin inhibited the transcriptional activity of peroxisome proliferator-activated receptor α through LPA-induced activation of extracellular signal-regulated kinas, thereby leading to suppression of hepatic FGF21 production. The therapeutic benefit of anti-autotaxin neutralizing antibody against NAFLD was abrogated in FGF21-null mice.

CONCLUSIONS

Liver-secreted autotaxin acts in an autocrine manner to exacerbate NAFLD through LPA-induced suppression of the peroxisome proliferator-activated receptor α-FGF21 axis and is a promising therapeutic target for NAFLD.

The Hypoglycemic Effect of JinQi Jiangtang Tablets Is Partially Dependent on the Palmatine-Induced Activation of the Fibroblast Growth Factor Receptor 1 Signaling Pathway

JinQi Jiangtang tablet (JQJTT) is a Chinese patent medicine that has been shown to be beneficial for patients with diabetes both preclinically and clinically; however, the molecular mechanism underlying the effects of JQJTT remains unclear. In this study, surface plasmon resonance fishing was employed to identify JQJTT constituent molecules that can specifically bind to fibroblast growth factor receptor 1 (FGFR1), leading to the retrieval of palmatine (PAL), a key active ingredient of JQJTT. In vivo and in vitro experiments demonstrated that PAL can significantly stimulate FGFR1 phosphorylation and upregulate glucose transporter type 1 (GLUT-1) expression, thereby facilitating glucose uptake in insulin resistance (IR) HepG2 cells as well as alleviating hyperglycemia in diabetic mice. Our results revealed that PAL functions as an FGFR1 activator and that the hypoglycemic effect of JQJTT is partially dependent on the PAL-induced activation of the FGFR1 pathway. In addition, this study contributed to the understanding the pharmacodynamic basis and mechanism of action of JQJTT and provided a novel concept for future research on PAL.

Fibroblast Growth Factor 19 Improves LPS-Induced Lipid Disorder and Organ Injury by Regulating Metabolomic Characteristics in Mice

Sepsis is extremely heterogeneous pathology characterized by complex metabolic changes. Fibroblast growth factor 19 (FGF19) is a well-known intestine-derived inhibitor of bile acid biosynthesis. However, it is largely unknown about the roles of FGF19 in improving sepsis-associated metabolic disorder and organ injury. In the present study, mice were intravenously injected recombinant human FGF19 daily for 7 days followed by lipopolysaccharide (LPS) administration. At 24 hours after LPS stimuli, sera were collected for metabolomic analysis. Ingenuity pathway analysis (IPA) network based on differential metabolites (DMs) was conducted. Here, metabolomic analysis revealed that FGF19 pretreatment reversed the increase of LPS-induced fatty acids. IPA network indicated that altered linoleic acid (LA) and gamma-linolenic acid (GLA) were involved in the regulation of oxidative stress and mitochondrial function and were closely related to reactive oxygen species (ROS) generation. Further investigation proved that FGF19 pretreatment decreased serum malondialdehyde (MDA) levels and increased serum catalase (CAT) levels. In livers, FGF19 suppressed the expression of inducible NO synthase (iNOS) and enhanced the expression of nuclear factor erythroid 2-related factor 2 (NRF2) and hemeoxygenase-1 (HO-1). Finally, FGF19 pretreatment protected mice against LPS-induced liver, ileum, and kidney injury. Taken together, FGF19 alleviates LPS-induced organ injury associated with improved serum LA and GLA levels and oxidative stress, suggesting that FGF19 might be a promising target for metabolic therapy for sepsis.

NAFLD: Mechanisms, Treatments, and Biomarkers

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-associated fatty liver disease (MAFLD), is one of the most common causes of liver diseases worldwide. NAFLD is growing in parallel with the obesity epidemic. No pharmacological treatment is available to treat NAFLD, specifically. The reason might be that NAFLD is a multi-factorial disease with an incomplete understanding of the mechanisms involved, an absence of accurate and inexpensive imaging tools, and lack of adequate non-invasive biomarkers. NAFLD consists of the accumulation of excess lipids in the liver, causing lipotoxicity that might progress to metabolic-associated steatohepatitis (NASH), liver fibrosis, and hepatocellular carcinoma. The mechanisms for the pathogenesis of NAFLD, current interventions in the management of the disease, and the role of sirtuins as potential targets for treatment are discussed here. In addition, the current diagnostic tools, and the role of non-coding RNAs as emerging diagnostic biomarkers are summarized. The availability of non-invasive biomarkers, and accurate and inexpensive non-invasive diagnosis tools are crucial in the detection of the early signs in the progression of NAFLD. This will expedite clinical trials and the validation of the emerging therapeutic treatments.

Molecular Basis of Bile Acid-FXR-FGF15/19 Signaling Axis

Bile acids (BAs) are a group of amphiphilic molecules consisting of a rigid steroid core attached to a hydroxyl group with a varying number, position, and orientation, and a hydrophilic side chain. While BAs act as detergents to solubilize lipophilic nutrients in the small intestine during digestion and absorption, they also act as hormones. Farnesoid X receptor (FXR) is a nuclear receptor that forms a heterodimer with retinoid X receptor α (RXRα), is activated by BAs in the enterohepatic circulation reabsorbed via transporters in the ileum and the colon, and plays a critical role in regulating gene expression involved in cholesterol, BA, and lipid metabolism in the liver. The FXR/RXRα heterodimer also exists in the distal ileum and regulates production of fibroblast growth factor (FGF) 15/FGF19, a hormone traveling via the enterohepatic circulation that activates hepatic FGF receptor 4 (FGFR4)-β-klotho receptor complex and regulates gene expression involved in cholesterol, BA, and lipid metabolism, as well as those regulating cell proliferation. Agonists for FXR and analogs for FGF15/19 are currently recognized as a promising therapeutic target for metabolic syndrome and cholestatic diseases.

Updates on novel pharmacotherapeutics for the treatment of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD), characterized with hepatocellular steatosis, ballooning, lobular inflammation, fibrotic progression, and insulin resistance. NASH may progress to cirrhosis and hepatocellular carcinoma (HCC), which are the major indications for liver transplantation and the causes for mortality. Thus far, there are no approved pharmacotherapeutics for the treatment of NASH. Given the complexity of NASH pathogenesis at multifaceted aspects, such as lipotoxicity, inflammation, insulin resistance, mitochondrial dysfunction and fibrotic progression, pharmacotherapeutics under investigation target different key pathogenic pathways to gain either the resolution of steatohepatitis or regression of fibrosis, ideally both. Varieties of pharmacologic candidates have been tested in clinical trials and have generated some positive results. On the other hand, recent failure or termination of a few phase II and III trials is disappointing in this field. In face to growing challenges in pharmaceutical development, this review intends to summarize the latest data of new medications which have completed phase II or III trials, and discuss the rationale and preliminary results of several combinatory options. It is anticipated that with improved understanding of NASH pathogenesis and critical endpoints, efficient pharmacotherapeutics will be available for the treatment of NASH with an acceptable safety profile.

The metabolic triad of non-alcoholic fatty liver disease, visceral adiposity and type 2 diabetes: Implications for treatment

Non-alcoholic fatty liver disease (NAFLD) is associated with visceral obesity, insulin resistance, type 2 diabetes (T2D) and has been often considered as the hepatic expression of the metabolic syndrome (MetS). Epidemiological studies highlight a bidirectional relationship of NAFLD with T2D in which NAFLD increases the risk of incident T2D and T2D increases the risk of severe non-alcoholic steatohepatitis (NASH) and liver fibrosis. Regarding the molecular determinants of NAFLD, we specifically focused in this review on adipocyte dysfunction as a key molecular link between visceral adipose tissue, MetS and NAFLD. Notably, the subcutaneous white adipose tissue expandability appears a critical adaptive buffering mechanism to prevent lipotoxicity and its related metabolic complications, such as NAFLD and T2D. There is a clinical challenge to consider therapeutic strategies targeting the metabolic dysfunction common to NASH and T2D pathogenesis. Strategies that promote significant and sustained weight loss (~10% of total body weight) such as metabolic and bariatric surgery or incretin-based therapies (GLP-1 receptor agonists or dual GLP-1/GIP or GLP-1/glucagon receptor co-agonists) are among the most efficient ones. In addition, insulin sensitizers such as PPARγ (pioglitazone) and pan-PPARs agonists (lanifibranor) have shown some beneficial effects on both NASH and liver fibrosis. Since NASH is a complex and multifactorial disease, it is conceivable that targeting different pathways, not only insulin resistance but also inflammation and fibrotic processes, is required to achieve NASH resolution.