Cilofexor, a Nonsteroidal FXR Agonist, in Patients With Noncirrhotic NASH: A Phase 2 Randomized Controlled Trial

Efficacy, Safety, and Tolerability of Farnesoid X Receptor Agonists in the Treatment of Metabolic Dysfunction-associated Steatotic Liver Disease: A Systematic Review and Meta-analysis

Background/Aims

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of chronic liver disease. Farnesoid X receptor (FXR) agonists are emerging as promising therapies for fibrosis, steatosis, and metabolic dysfunctions. However, its efficacy and safety remain unclear.

Methods

A systematic search of PubMed, Embase, and Cochrane databases identified randomized controlled trials (RCTs) comparing FXR agonists with placebo in patients with MASLD. The main outcomes included improvement in fibrosis without worsening steatohepatitis, changes in liver chemistry and lipid profiles, and liver fat content (LFC). The safety outcomes assessed included side effects and treatment discontinuation rates. Heterogeneity was evaluated using I² statistics, with a random-effects model applied to the pooled analyses.

Results

Ten RCTs involving 3,779 patients were included, of which 2,527 (67%) were randomized to receive FXR agonists. FXR agonists significantly improved fibrosis by ≥ 1 stage (RR, 1.52; 95% CI: [1.23, 1.88]; P < 0.0001) and reduced LFC (mean difference: -4.9%; 95% CI: [-8.26, -1.55]; P < 0.001). A higher proportion of patients achieved a ≥30% reduction in LFC (42.8% vs. 18.4%; RR, 2.42; 95% CI: [1.69, 3.46]; P < 0.00001). Significant reductions in alanine aminotransferase and gamma glutamyltransferase levels were observed, whereas alkaline phosphatase levels were increased. FXR agonists were associated with a slight reduction in High-Density Lipoprotein (HDL) cholesterol levels and a higher incidence of pruritus (37.8% vs. 18.7%; RR, 2.67; 95% CI: [1.63, 4.38]; P < 0.00001), leading to higher treatment discontinuation rates.

Conclusion

FXR agonists have the potential to improve fibrosis and steatosis in MASLD patients. However, safety concerns still remain. Further research is required to determine the long-term efficacy and tolerability of these drugs.

Insights into Clinical Trials for Drugs Targeting MASLD: Progress, Challenges, and Future Directions

The transition in terminology from fatty liver disease to metabolic dysfunction-associated steatotic liver disease (MASLD) marks a considerable evolution in diagnostic standards. This new definition focuses on liver fat accumulation in the context of overweight/obesity, type 2 diabetes, or metabolic dysfunction, without requiring the exclusion of other concurrent liver diseases. The new definition also provides clear guidelines for defining alcohol consumption in relation to the disease. MASLD is currently acknowledged as the most widespread liver disorder globally, affecting ~25% of the population. Despite the extensive array of clinical trials conducted in recent years, the number of approved treatments for metabolic dysfunction-associated fatty liver disease is very limited. In the review critically evaluates the results of clinical trials of related drugs and assesses the future directions for drug development trials. The renaming of MASLD presents new challenges and opportunities for the design of clinical trials and the selection of target populations for drug development.

Schisandra chinensis lignans ameliorate hepatic inflammation and steatosis in methionine choline-deficient diet-fed mice by modulating the gut-liver axis

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis is used as a traditional Chinese medicine to treat a variety of diseases. Schisandra chinensis lignans (SCL) are one of the most active components extracted from Schisandrae chinensis fructus, exhibit a broad array of pharmacological properties, especially anti-inflammatory and hepatic lipid-lowering effects, suggesting SCL may have potential anti-nonalcoholic steatohepatitis (NASH) ability. However, the therapeutic efficacy of SCL against NASH and the underlying mechanism of this action remains unclear.

AIM OF THE STUDY

In the current study, we aimed to investigate the anti-NASH action of SCL and explore the underlying mechanism in vitro and in vivo. We also assess the involvement of the gut-liver axis in the anti-NASH effects of SCL.

METHODS

Palmitic acid (PA)-treated HepG2 cells, mouse primary hepatocytes (MPHs) and methionine-choline deficient (MCD) diet-fed mice were selected as NASH models. ORO staining and qRT-PCR were performed to assess hepatic steatosis and inflammatory responses, respectively. Masson's trichrome staining was used to detect the liver fibrosis. Protein expression was detected by Western blotting or immunohistochemistry. The changes of gut microbiota were analyzed using 16S rDNA sequencing in mice. The levels of metabolites in liver and feces were measured by metabolomics.

RESULTS

The results showed that SCL treatment alleviated steatosis and inflammation in palmitic acid (PA)-treated HepG2 cells and mouse primary hepatocytes (MPHs). SCL treatment suppressed the phosphorylation of key components involved in NF-κB signaling and enhanced the expression of fatty acid oxidation (FAO)-related enzymes (e.g. CPT1, HMGCS2, and ACOX1) in PA-treated HepG2 cells. SCL could ameliorate hepatic steatosis and inflammation in NASH mice. SCL also ameliorated intestinal barrier injury and restructured the gut microbiota in NASH mice. SCL also modulated hepatic and colonic bile acid metabolism via FXR signaling.

CONCLUSION

These findings indicate that SCL treatment ameliorates hepatic inflammation and steatosis in NASH mice, potentially though to the suppression of NF-κB signaling and the promotion of fatty acid β-oxidation. Moreover, SCL could restore gut microbiota-mediated bile acid homeostasis via activation of FXR/FGF15 signaling. Our study presents a pharmacological rationale for using SCL in the management of NASH.

The bile acid-gut microbiota axis: A central hub for physiological regulation and a novel therapeutic target for metabolic diseases

Bile acids are a family of signaling molecules synthesized in the liver and metabolized by gut bacteria. As metabolites of the intestinal microbiota, bile acids bind to various receptors, and affect the metabolism and immune function of the host, including glucose and lipid metabolism, energy homeostasis, and inflammatory response. Conversely, bile acids also shape the composition of the gut microbiota. Given their critical role in physiological regulation, disrupted bile acid signaling is closely linked to metabolic diseases. Consequently, therapeutic strategies targeting bile acids are increasingly being explored. The size, composition, and function of the bile acid pool can be modulated through direct treatments (e.g., bile acid replacement therapy, administration of bile acid receptor agonists/antagonists) or indirect treatments (e.g., gut microbiota modulation, probiotic supplementation), providing new ideas for preventing and treating metabolic diseases.

Fexaramine as the intestine-specific farnesoid X receptor agonist: A promising agent to treat obesity and metabolic disorders

Fexaramine, a gut-restricted farnesoid X receptor (FXR) agonist, promotes glucose and lipid homeostasis, improves insulin sensitivity, promotes white adipose tissue browning, and stimulates nonshivering thermogenesis. Enhancement in energy expenditure due to an increase in amount of energy burned by brown and 'beige' adipocytes results in subsequent weight loss. Fexaramine is poorly absorbed into circulation when delivered orally, which limits systemic FXR activation and toxicity. An increase in β3-adrenoceptor signaling, activation of Takeda G protein-coupled receptor 5/glucagon-like peptide-1 (TGR5/GLP-1) signaling, and induction of fibroblast growth factor (FGF)-19/FGF-15 play crucial roles in fexaramine metabolic actions. Intestinal FXR activation is a promising, potentially safe approach for treating obesity and metabolic syndrome.

Chronic Inflammation and Immune Dysregulation in Metabolic-Dysfunction-Associated Steatotic Liver Disease Progression: From Steatosis to Hepatocellular Carcinoma

Background/Objectives: Metabolic-dysfunction-associated steatotic liver disease (MASLD) progresses from hepatic steatosis to hepatocellular carcinoma (HCC) as a result of systemic immunometabolic dysfunction. This review summarizes the key roles of the innate and adaptive immune mechanisms driving hepatic injury, fibrogenesis, and carcinogenesis in MASLD. Methods: A comprehensive literature review was performed using PubMed to identify relevant published studies. Eligible articles included original research and clinical studies addressing immunological and metabolic mechanisms in MASLD, as well as emerging therapeutic strategies. Results: We highlight the roles of cytokine networks, the gut-liver axis, and immune cell reprogramming. Emerging therapeutic strategies, including cytokine inhibitors, anti-fibrotic agents, metabolic modulators, and nutraceuticals, offer several indications for attenuating MASLD progression and reducing the prevalence of extrahepatic manifestations. Conclusions: Given the heterogeneity of MASLD, personalized combination-based approaches targeting both inflammation and metabolic stress are essential for effective disease management and the prevention of systemic complications.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of INT-787, a Novel Farnesoid X Receptor Agonist, in Healthy Volunteers: A Phase 1 Trial

Aberrant farnesoid X receptor (FXR) signaling is implicated in cholestatic, inflammatory, and fibrotic liver diseases. In preclinical/clinical studies, semisynthetic bile acid-derived FXR agonists markedly improved hepatic function in various conditions. INT-787, a novel hydrophilic semisynthetic bile acid FXR agonist, has demonstrated a reduction in inflammatory and fibrotic markers and regulation of bile acid/lipid metabolism. This first-in-human, randomized, placebo-controlled phase 1 study assessed the safety, tolerability, pharmacokinetics, and pharmacodynamics of INT-787 and its equipotent metabolites in healthy volunteers by evaluating single ascending doses (SAD), multiple ascending doses (MAD), and food effect. Participants (n = 130) across all study portions were similar in age, race, and body mass index. In the SAD and MAD portions, the maximum plasma concentration (Cmax) and area under the curve (AUC) for total INT-787 generally increased with dose. In the Food Effect portion, the mean Cmax of total INT-787 was almost 2-fold higher under fasted conditions compared with fed conditions; AUC0-inf was unchanged. Steady state for total INT-787 was reached by Day 7. In cohorts receiving ≥ 50 mg doses, the half-life of total INT-787 ranged from 21 to 55 h. INT-787 metabolites exhibited increased concentrations after mealtimes despite morning dosing, consistent with endogenous bile acid behavior. Following single and multiple doses of INT-787, decreases in C4 and increases in FGF-19 levels were observed. Single and multiple oral doses were generally well tolerated; 4 adverse events of mild, transient pruritus not requiring interventions were reported at higher doses. These results warrant further investigation of INT-787 in patients with liver-related disorders.

Targeting Metabolism: Innovative Therapies for MASLD Unveiled

The recent introduction of the term metabolic-dysfunction-associated steatotic liver disease (MASLD) has highlighted the critical role of metabolism in the disease's pathophysiology. This innovative nomenclature signifies a shift from the previous designation of non-alcoholic fatty liver disease (NAFLD), emphasizing the condition's progressive nature. Simultaneously, MASLD has become one of the most prevalent liver diseases worldwide, highlighting the urgent need for research to elucidate its etiology and develop effective treatment strategies. This review examines and delineates the revised definition of MASLD, exploring its epidemiology and the pathological changes occurring at various stages of the disease. Additionally, it identifies metabolically relevant targets within MASLD and provides a summary of the latest metabolically targeted drugs under development, including those in clinical and some preclinical stages. The review finishes with a look ahead to the future of targeted therapy for MASLD, with the goal of summarizing and providing fresh ideas and insights.

Restoring FXR expression as a novel treatment strategy in liver cancer and other liver disorders

INTRODUCTION

Liver cancer is a leading cause of cancer-associated mortality and is often linked to preexisting liver conditions. Emerging research demonstrates FXR dysregulation, particularly its reduced expression, in the pathogenesis of liver diseases, including inflammation, fibrosis, cholestatic disorders, metabolic dysregulation, and liver cancer. Therefore, this review explores the role of FXR and its agonists in mitigating these conditions.

AREAS COVERED

This article summarizes FXR's involvement in liver disorders, primarily emphasizing on hepatic neoplasms, and examines the potential of FXR agonists in restoring FXR activity in liver diseases, thereby preventing their progression to liver cancer. The information presented is drawn from existing preclinical and clinical studies specific to each liver disorder, sourced from PubMed.

EXPERT OPINION

It is well established that FXR expression is downregulated in liver disorders, contributing to disease progression. Notably, FXR agonists have demonstrated therapeutic potential in ameliorating liver diseases, including hepatocellular carcinoma. We believe that activating or restoring FXR expression with agonists offers significant promise for the treatment of liver cancer and other liver conditions. Therefore, FXR modulation by agonists, particularly in combination with other therapeutic agents, could lead to more targeted treatments, improving efficacy while reducing side effects.

Bile acids and their receptors in hepatic immunity

Similarly to conventional steroids, bile acids function as signaling molecules, acting on a family of membrane and nuclear receptors. The best-characterized bile acid-regulated receptors are the farnesoid X receptor, activated by primary bile acids, and the G-protein-coupled bile acid receptor 1 (also known as Takeda G protein-coupled receptor 5), which is activated by secondary bile acids, such as lithocholic acid (LCA) and deoxycholic acid. Both the farnesoid X receptor and G-protein-coupled bile acid receptor 1 are expressed in cells of innate immunity, monocytes/macrophages, and natural killer cells. Their activation in these cells provides counter-regulatory signals that are inhibitory in nature and attenuate inflammation. In recent years, however, it has been increasingly appreciated that bile acids biotransformations by intestinal microbiota result in the formation of chemically different secondary bile acids that potently regulate adaptive immunity. The 3-oxoLCA and isoalloLCA, two LCA derivatives, bind receptors such as the retinoic acid receptor-related orphan receptor gamma t (RORγt) and the vitamin D receptor (VDR) that are expressed only by lymphoid cells, extending the regulatory role of bile acids to T cells, including T-helper 17 cells and type 3 innate lymphoid cells (ILC3). In this novel conceptual framework, bile acids have emerged as one of the main components of the postbiota, the waste array of chemical mediators generated by the intestinal microbiota. Deciphering the interaction of these mediators with the immune system in the intestine and liver is a novel and fascinating area of bile acid renaissance.

Treating metabolic dysfunction-associated steatohepatitis: The fat-trimming FGF21 approach

Metabolic dysfunction-associated steatohepatitis (MASH) is a condition characterized by hepatosteatosis, inflammation, and tissue damage, with steatosis as the initial stage, which involves chronic, excess deposition of lipids in hepatic lipid droplets. Despite the growing prevalence and serious risks it poses, including liver decompensation, the need for transplantation, and increased patient mortality, MASH currently faces no approved pharmacotherapy. Several promising treatment candidates have emerged from recent clinical trials, including analogs of FGF21 and agonists of the associated FGFR1-KLB complex. These agents were well-tolerated in trials and have demonstrated significant improvements in both histological and biochemical markers of liver fat content, inflammation, injury, and fibrosis in patients with MASH. Endocrine FGF21 plays a vital role in maintaining homeostasis of lipid, glucose, and energy metabolism. It achieves this through pathways that target lipids or lipid droplets in adipocytes and hepatocytes. Mechanistically, pharmacological FGF21 acts as a potent catabolic factor to promote lipid or lipid droplet lipolysis, fatty acid oxidation, mitochondrial catabolic flux, and heat-dissipating energy expenditure, leading to effective clearance of hepatic and systemic gluco-lipotoxicity and inflammatory stress, thereby preventing obesity, diabetes, and MASH pathologies. In this review, we aim to provide an update on the outcomes of clinical trials for several FGF21 mimetics. We compare these outcomes with preclinical studies and offer a lipid-centric perspective on the mechanisms underlying the clinical benefits of these agents for MASH.

Meta-Analysis of Placebo-Treated Patients: Dropout Rates From Treatment in MASH Randomised Controlled Trials

BACKGROUND

Dropout is common and affects the statistical power and randomization balance of randomised controlled trials (RCTs).

AIMS

To estimate the dropout rate in RCTs of metabolic dysfunction-associated steatohepatitis (MASH) and to examine factors associated with dropout in placebo-treated participants.

METHODS

PubMed and Cochrane databases were searched for phase 2-4 MASH RCTs with placebo arms through November 24, 2024. Dropout was defined as the attrition of patients included in the intention-to-treat analysis but did not complete treatment. RCTs were qualitatively reviewed to assess the expected and observed dropouts. Generalised linear mixed model was used to estimate pooled dropout rates.

RESULTS

Sixty RCTs with 3230 placebo-treated participants with MASH were analysed. Thirty-three RCTs reported the dropout rate used to estimate the effect size. Of these, 60.6%, 36.4%, and 3.0% had an expected dropout rate that was higher, lower, and similar, respectively, than the observed dropout rate in the placebo arm. Overall, the dropout rate was 11.06% (95% confidence interval [CI] 9.07 to 13.42), with a higher rate in phase 3-4 trials than in phase 2 trials. The corresponding rates due to adverse events, loss to follow-up and patient choice were 2.41% (95% CI 1.67 to 3.48), 1.79% (95% CI 1.06 to 2.99) and 4.06% (95% CI 2.97 to 5.53), respectively. Meta-regression determined that the dropout rate increased with longer treatment duration.

CONCLUSION

Placebo dropout in MASH RCTs is significant, mainly due to patient choice. Factors such as trial phase and treatment duration should be considered when calculating sample size in future clinical trials.

Simulations Reveal Unique Roles for the FXR Hinge in the FXR-RXR Nuclear Receptor Heterodimer

Nuclear receptors are multidomain transcription factors whose full-length quaternary architecture is poorly described and understood. Most nuclear receptors bind DNA as heterodimers or homodimers, which could encompass a variety of arrangements of the individual domains. Only a handful of experimental structures currently exist describing these architectures. Given that domain interactions and protein-DNA interactions within transcriptional complexes are tightly linked to function, understanding the arrangement of nuclear receptor domains on DNA is of utmost importance. Here, we employ modeling and molecular dynamics (MD) simulations to describe the structure of the full-length farnesoid X receptor (FXR) and retinoid X receptor alpha (RXR) heterodimer bound to DNA. Combining over 100 μs of atomistic MD simulations with enhanced sampling simulations, we characterize the dynamic behavior of eight FXR-RXR-DNA complexes, showing that these complexes support a range of quaternary architectures. Our simulations reveal critical roles for the hinge in the DNA-bound dimer in facilitating interdomain allostery, mediating DNA binding and driving the dynamic flexibility of the complex. These roles have been hard to appreciate previously due to experimental limitations in studying the flexible hinge. These studies provide a much-needed framework that will enable the field to obtain a complete understanding of nuclear receptor quaternary architectures.

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.

Therapeutic Targets and Approaches to Manage Inflammation of NAFLD

Non-alcoholic fatty liver disease (NAFLD) and its advanced form, non-alcoholic steatohepatitis (NASH), are the leading causes of chronic liver disease globally. They are driven by complex mechanisms where inflammation plays a pivotal role in disease progression. Current therapies, including lifestyle changes and pharmacological agents, are limited in efficacy, particularly in addressing the advanced stages of the disease. Emerging approaches targeting inflammation, metabolic dysfunction, and fibrosis offer promising new directions, though challenges such as treatment complexity and heterogeneity persist. This review concludes the main therapeutic targets and approaches to manage inflammation currently and emphasizes the critical need for future drug development and combination therapy for NAFLD/NASH management.

Enhanced dynamic coupling in a nuclear receptor underlies ligand activity

Bile acids are signaling molecules with critical roles in cholesterol and lipid metabolism, achieved by regulating the transcriptional activity of the farnesoid X receptor (FXR, NR1H4), otherwise known as the bile acid receptor. Modifications to the C6 position of the steroidal core yield bile acid derivatives with 100× improved potency over endogenous bile acids. Prevailing hypotheses suggested increased binding affinity for FXR as the driver for this activity enhancement. Our experimental results contradict this suggestion, motivating us to investigate the underlying mechanisms of enhanced ligand activity. We combined functional assays with over 200 μs of simulations, revealing an unexpected role for helix 5 in the allosteric signaling of obeticholic acid. We uncovered dynamic coupling between adjacent helices 5 and 7, which is uniquely enhanced by the bile acid modification. Ultimately, the enhanced potency of the bile acid analog can be traced to its effect on FXR dynamics. In addition to identifying a previously unknown mechanistic role for helix 5 to helix 7 coupling in FXR, these results emphasize the inextricable linkage between the activity of nuclear receptor ligands and their effects on receptor dynamics.

Drug Advances in NAFLD: Individual and Combination Treatment Strategies of Natural Products and Small-Synthetic-Molecule Drugs

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease and is closely associated with metabolic diseases such as obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome. However, effective treatment strategies for NAFLD are still lacking. In recent years, progress has been made in understanding the pathogenesis of NAFLD, identifying multiple therapeutic targets and providing new directions for drug development. This review summarizes the recent advances in the treatment of NAFLD, focusing on the mechanisms of action of natural products, small-synthetic-molecule drugs, and combination therapy strategies. This review aims to provide new insights and strategies in treating NAFLD.

Design, synthesis, and biological evaluation of novel highly potent FXR agonists bearing piperidine scaffold

Metabolic dysfunction-associated steatohepatitis (MASH) has become a serious threat to human health, which exhibited an increasing prevalence globally. Recently, the farnesoid X receptor (FXR) has been identified as a promising strategy for the treatment of MASH by regulating multiple pathogenesis. In this study, a new series of FXR agonists bearing piperidine scaffold was designed to reduce the high lipophilicity of the existing FXR agonists. After comprehensive multiparameter optimization, LZ-007 was discovered as a highly potent FXR agonist with suitable stability in liver microsomes of multiple species. LZ-007 exhibited highly oral bioavailability and targeted tissue exposure in the liver and ileum, while the plasma exposure is low, which might minimize the systemic side effects. Moreover, LZ-007 was significantly up-regulated the expressions of FXR and its downstream genes in the liver and ileum. In MASH model, LZ-007 exerted potent anti-MASH effects by regulating the multiple signal pathways related to lipid metabolism, oxidative stress, inflammation and fibrosis. In a 30-day toxicity study, no apparent adverse effects were observed in LZ-007 treated groups, even at the high doses of 250 and 500 mg/kg. With the positive pharmacodynamics and safety profiles, LZ-007 is worthy of further evaluation as a new anti-MASH agent.

Novel targets for mucosal healing in inflammatory bowel disease therapy

Inflammatory bowel disease (IBD) is a chronic condition affecting the gastrointestinal tract, primarily manifesting as ulcerative colitis (UC) or Crohn's disease (CD). Both inflammation and disruption of the intestinal epithelial barrier are key factors in IBD pathogenesis. Substantial evidence has revealed a significant association between aberrant immune responses and impairment of the intestinal epithelial barrier in IBD pathogenesis. The components of the intestinal epithelium, particularly goblet cells and Paneth cells, are crucial to gut homeostasis, as they secrete mucin, antimicrobial peptides (AMPs), and cytokines. Furthermore, impairment of epithelial integrity, which is regulated by tight junctions, is a hallmark of IBD pathology. While common treatments for IBD, such as anti-inflammatory drugs, target various signaling pathways with varying efficacies, therapeutic approaches focused on mucosal and epithelial barrier healing have been largely neglected. Moreover, high costs, side effects, and insufficient or inconsistent therapeutic outcomes remain major drawbacks of conventional anti-IBD drugs. Recent studies on epithelial barrier regeneration and permeability reduction have introduced promising therapeutic targets, including farnesoid X receptor (FXR), urokinase-type plasminogen activator (uPA)-urokinase-type plasminogen activator receptor (uPAR) interaction, fecal microbiota transplantation (FMT), and insulin receptor (INSR). Notably, the simultaneous targeting of intestinal inflammation and promotion of epithelial barrier healing shows promise for efficient IBD treatment. Future research should explore targeted therapies and combination treatments, including natural remedies, microbiota colonization, stem cell approaches, and computer-aided drug design. It is also crucial to focus on accurate prognosis and developing a thorough understanding of IBD development mechanisms.

Lipotoxicity-driven metabolic dysfunction-associated steatotic liver disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a spectrum of liver lesions, ranging from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH), that may further progress to cirrhosis. MASLD is estimated to affect more than one third of the general population and it represents a risk factor for end-stage liver failure and liver cancer, substantially contributing to liver-related morbidity and mortality. Although the pathogenesis of MASLD is incompletely understood, it is known to consist of a multifactorial process influenced by extrinsic and intrinsic factors such as metabolic, environmental and demographic features, gut microbiota and genetics. Dysregulation of both extracellular and intracellular lipid composition is known to promote the generation of toxic lipid species, thereby triggering lipotoxicity and cellular stress. These events ultimately lead to the activation of distinct cell death pathways, resulting in inflammation, fibrogenesis and, eventually, carcinogenesis. In this manuscript, we provide a comprehensive review of the role of lipotoxicity during MASLD pathogenesis, discussing the most relevant lipid species and related molecular mechanisms, summarizing the cell type-specific effects and highlighting the most promising putative therapeutic strategies for modulating lipotoxicity and lipid metabolism in MASLD.

Targeting Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Available and Future Pharmaceutical Options

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects an ever-increasing part of the global population, affecting millions of individuals worldwide. Despite the progress in the treatment of other liver diseases, there is a scarcity of liver-specific drugs targeting MASLD. In light of that, research has focused both on pipeline drugs targeting multiple different receptors implicated in the pathogenesis of the disease, as well as medications already approved for other indications, that might exert beneficial effects on MASLD. The fact that MASLD is associated with an increased prevalence of obesity and type 2 diabetes mellitus (T2DM) establishes a possible pathway with respect to already available pharmaceutical interventions for this group of patients, such as glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose co-transporter-2 inhibitors (SGLT2-is). Thus, the hitherto at hand, along with the upcoming members of these families, provide much-needed options for our arsenal. This review attempts to explore old and novel dimensions of the pharmaceutical treatment of MASLD in the continuous effort of the medical society to improve patient outcomes.

Bile acid metabolism and signalling in liver disease

Bile acids (BAs) serve as signalling molecules, efficiently regulating their own metabolism and transport, as well as key aspects of lipid and glucose homeostasis. BAs shape the gut microbial flora and conversely are metabolised by microbiota. Disruption of BA transport, metabolism and physiological signalling functions contribute to the pathogenesis and progression of a wide range of liver diseases including cholestatic disorders and MASLD (metabolic dysfunction-associated steatotic liver disease), as well as hepatocellular and cholangiocellular carcinoma. Additionally, impaired BA signalling may also affect the intestine and kidney, thereby contributing to failure of gut integrity and driving the progression and complications of portal hypertension, cholemic nephropathy and the development of extrahepatic malignancies such as colorectal cancer. In this review, we will summarise recent advances in the understanding of BA signalling, metabolism and transport, focusing on transcriptional regulation and novel BA-focused therapeutic strategies for cholestatic and metabolic liver diseases.

[Ferroptosis and liver diseases]

As the central organ of metabolism, the liver plays a pivotal role in the regulation of the synthesis and metabolism of various nutrients within the body. Ferroptosis, as a newly discovered type of programmed cell death caused by the accumulation of iron-dependent lipid peroxides, is involved in the physiological and pathological processes of a variety of acute and chronic liver diseases. Ferroptosis can accelerate the pathogenetic process of acute liver injury, metabolic associated fatty liver disease, alcoholic liver disease, viral hepatitis, and autoimmune hepatitis; while it can slower disease progression in advanced liver fibrosis and hepatocellular carcinoma. This suggests that targeted regulation of ferroptosis may impact the occurrence and development of various liver diseases. This article reviews the latest research progress of ferroptosis in various liver diseases, including acute liver injury, metabolic associated fatty liver disease, alcoholic liver disease, viral hepatitis, autoimmune hepatitis, liver fibrosis and hepatocellular carcinoma. It aims to provide insights for the prevention and treatment of acute and chronic liver diseases through targeting ferroptosis.

Diverting hepatic lipid fluxes with lifestyles revision and pharmacological interventions as a strategy to tackle steatotic liver disease (SLD) and hepatocellular carcinoma (HCC)

Steatotic liver disease (SLD) and Hepatocellular Carcinoma (HCC) are characterised by a substantial rewiring of lipid fluxes caused by systemic metabolic unbalances and/or disrupted intracellular metabolic pathways. SLD is a direct consequence of the interaction between genetic predisposition and a chronic positive energy balance affecting whole-body energy homeostasis and the function of metabolically-competent organs. In this review, we discuss how the impairment of the cross-talk between peripheral organs and the liver stalls glucose and lipid metabolism, leading to unbalances in hepatic lipid fluxes that promote hepatic fat accumulation. We also describe how prolonged metabolic stress builds up toxic lipid species in the liver, and how lipotoxicity and metabolic disturbances drive disease progression by promoting a chronic activation of wound healing, leading to fibrosis and HCC. Last, we provide a critical overview of current state of the art (pre-clinical and clinical evidence) regarding mechanisms of action and therapeutic efficacy of candidate SLD treatment options, and their potential to interfere with SLD/HCC pathophysiology by diverting lipids away from the liver therefore improving metabolic health.

Pharmacotherapy of Liver Fibrosis and Hepatitis: Recent Advances

Liver fibrosis is a progressive scarring process primarily caused by chronic inflammation and injury, often closely associated with viral hepatitis, alcoholic liver disease, metabolic dysfunction-associated steatotic liver disease (MASLD), drug-induced liver injury, and autoimmune liver disease (AILD). Currently, there are very few clinical antifibrotic drugs available, and effective targeted therapy is lacking. Recently, emerging antifibrotic drugs and immunomodulators have shown promising results in animal studies, and some have entered clinical research phases. This review aims to systematically review the molecular mechanisms underlying liver fibrosis, focusing on advancements in drug treatments for hepatic fibrosis. Furthermore, since liver fibrosis is a progression or endpoint of many diseases, it is crucial to address the etiological treatment and secondary prevention for liver fibrosis. We will also review the pharmacological treatments available for common hepatitis leading to liver fibrosis.

Structure-guided discovery of bile acid derivatives for treating liver diseases without causing itch

Chronic itch is a debilitating symptom profoundly impacting the quality of life in patients with liver diseases like cholestasis. Activation of the human G-protein coupled receptor, MRGPRX4 (hX4), by bile acids (BAs) is implicated in promoting cholestasis itch. However, the detailed underlying mechanisms remain elusive. Here, we identified 3-sulfated BAs that are elevated in cholestatic patients with itch symptoms. We solved the cryo-EM structure of hX4-Gq in a complex with 3-phosphated deoxycholic acid (DCA-3P), a mimic of the endogenous 3-sulfated deoxycholic acid (DCA-3S). This structure revealed an unprecedented ligand-binding pocket in MRGPR family proteins, highlighting the crucial role of the 3-hydroxyl (3-OH) group on BAs in activating hX4. Guided by this structural information, we designed and developed compound 7 (C7), a BA derivative lacking the 3-OH. Notably, C7 effectively alleviates hepatic injury and fibrosis in liver disease models while significantly mitigating the itch side effects.

Endothelial Dysfunction and Liver Cirrhosis: Unraveling of a Complex Relationship

Endothelial dysfunction (ED) is the in the background of multiple metabolic diseases and a key process in liver disease progression and cirrhosis decompensation. ED affects liver sinusoidal endothelial cells (LSECs) in response to different damaging agents, causing their progressive dedifferentiation, unavoidably associated with an increase in intrahepatic resistance that leads to portal hypertension and hyperdynamic circulation with increased cardiac output and low peripheral artery resistance. These changes are driven by a continuous interplay between different hepatic cell types, invariably leading to increased reactive oxygen species (ROS) formation, increased release of pro-inflammatory cytokines and chemokines, and reduced nitric oxide (NO) bioavailability, with a subsequent loss of proper vascular tone regulation and fibrosis development. ED evaluation is often accomplished by serum markers and the flow-mediated dilation (FMD) measurement of the brachial artery to assess its NO-dependent response to shear stress, which usually decreases in ED. In the context of liver cirrhosis, the ED assessment could help understand the complex hemodynamic changes occurring in the early and late stages of the disease. However, the instauration of a hyperdynamic state and the different NO bioavailability in intrahepatic and systemic circulation-often defined as the NO paradox-must be considered confounding factors during FMD analysis. The primary purpose of this review is to describe the main features of ED and highlight the key findings of the dynamic and intriguing relationship between ED and liver disease. We will also focus on the significance of FMD evaluation in this setting, pointing out its key role as a therapeutic target in the never-ending battle against liver cirrhosis progression.

Decreasing the burden of non-alcoholic fatty liver disease: From therapeutic targets to drug discovery opportunities

Non-alcoholic fatty liver disease (NAFLD) presents a pervasive global pandemic, affecting approximately 25 % of the world's population. This grave health issue not only demands urgent attention but also stands as a significant economic concern on a global scale. The genesis of NAFLD can be primarily attributed to unhealthy dietary habits and a sedentary lifestyle, albeit certain genetic factors have also been recorded to contribute to its occurrence. NAFLD is characterized by fat accumulation in more than 5 % of hepatocytes according to histological analysis, or >5.6 % of lipid volume fraction in total liver weight in patients. The pathophysiology of NAFLD/non-alcoholic steatohepatitis (NASH) is multifactorial and the mechanisms underlying the progression to advanced forms remain unclear, thereby representing a challenge to disease therapy. Despite the substantial efforts from the scientific community and the large number of pre-clinical and clinical trials performed so far, only one drug was approved by the Food and Drug Administration (FDA) to treat NAFLD/NASH specifically. This review provides an overview of available information concerning emerging molecular targets and drug candidates tested in clinical studies for the treatment of NAFLD/NASH. Improving our understanding of NAFLD pathophysiology and pharmacotherapy is crucial not only to explore new molecular targets, but also to potentiate drug discovery programs to develop new therapeutic strategies. This knowledge endeavours scientific efforts to reduce the time for achieving a specific and effective drug for NAFLD or NASH management and improve patients' quality of life.

Design, Synthesis, and Pharmacological Evaluation of Dual FXR-LIFR Modulators for the Treatment of Liver Fibrosis

Although multiple approaches have been suggested, treating mild-to-severe fibrosis in the context of metabolic dysfunction associated with liver disease (MASLD) remains a challenging area in drug discovery. Pathogenesis of liver fibrosis is multifactorial, and pathogenic mechanisms are deeply intertwined; thus, it is well accepted that future treatment requires the development of multitarget modulators. Harnessing the 3,4,5-trisubstituted isoxazole scaffold, previously described as a key moiety in Farnesoid X receptor (FXR) agonism, herein we report the discovery of a novel class of hybrid molecules endowed with dual activity toward FXR and the leukemia inhibitory factor receptor (LIFR). Up to 27 new derivatives were designed and synthesized. The pharmacological characterization of this series resulted in the identification of 3a as a potent FXR agonist and LIFR antagonist with excellent ADME properties. In vitro and in vivo characterization identified compound 3a as the first-in-class hybrid LIFR inhibitor and FXR agonist that protects against the development of acute liver fibrosis and inflammation.

Protein posttranslational modifications in metabolic diseases: basic concepts and targeted therapies

Metabolism-related diseases, including diabetes mellitus, obesity, hyperlipidemia, and nonalcoholic fatty liver disease, are becoming increasingly prevalent, thereby posing significant threats to human health and longevity. Proteins, as the primary mediators of biological activities, undergo various posttranslational modifications (PTMs), including phosphorylation, ubiquitination, acetylation, methylation, and SUMOylation, among others, which substantially diversify their functions. These modifications are crucial in the physiological and pathological processes associated with metabolic disorders. Despite advancements in the field, there remains a deficiency in contemporary summaries addressing how these modifications influence processes of metabolic disease. This review aims to systematically elucidate the mechanisms through which PTM of proteins impact the progression of metabolic diseases, including diabetes, obesity, hyperlipidemia, and nonalcoholic fatty liver disease. Additionally, the limitations of the current body of research are critically assessed. Leveraging PTMs of proteins provides novel insights and therapeutic targets for the prevention and treatment of metabolic disorders. Numerous drugs designed to target these modifications are currently in preclinical or clinical trials. This review also provides a comprehensive summary. By elucidating the intricate interplay between PTMs and metabolic pathways, this study advances understanding of the molecular mechanisms underlying metabolic dysfunction, thereby facilitating the development of more precise and effective disease management strategies.

Current Progress and Challenges in the Development of Pharmacotherapy for Metabolic Dysfunction-Associated Steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH), a severe form of metabolic dysfunction-associated steatotic liver disease (MASLD), poses a significant threat to global health. Despite extensive research efforts over the past decade, only one drug has received market approval under accelerated pathways. In this review, we summarise the pathogenesis of MASH and present a comprehensive overview of recent advances in phase 2-3 clinical trials targeting MASH. These trials have highlighted considerable challenges, including low response rates to drugs, limitations of current surrogate histological endpoints, and inadequacies in the design of MASH clinical trials, all of which hinder the progress of MASH pharmacotherapy. We also explored the potential of non-invasive tests to enhance clinical trial design. Furthermore, given the strong association between MASLD and cardiometabolic disorders, we advocate for an integrated approach to disease management to improve overall patient outcomes. Continued investigation into the mechanisms and pharmacology of combination therapies may offer valuable insights for developing innovative MASH treatments.

Unravelling the therapeutic landscape of bile acid-based therapies in gastrointestinal disorders

ABSTRACT

Bile acids serve as endogenous ligands for nuclear and cell membrane receptors and play a crucial role in bile acid and lipid metabolism. These detergent-like compounds promote bile flow and aid in the absorption of dietary fats and fat-soluble vitamins in the intestine. Synthesized in the liver as end products of cholesterol catabolism, bile acids exhibit a chemical structure comprising a nucleus and a side chain featuring a carboxyl group, with diverse steric arrangements and potential polar substituents. Critical interactions occur between bile acid species and various nuclear and cell membrane receptors, including the farnesoid X receptor and G-protein-coupled bile acid receptor 1. This research aimed to review the literature on bile acids and their roles in treating different diseases. Currently, numerous investigations are concentrating on specific bile acid species that target nuclear receptors in the gastrointestinal system, aiming to improve the treatment of conditions such as nonalcoholic fatty liver disease. Given the global attention this topic has garnered from research groups, it is considered relatively new, thus anticipating some gaps or incomplete data. Bile acid species have a significant therapeutic promise, especially in their ability to activate or inhibit nuclear receptors, such as farnesoid X receptor. This research provides to offer essential information for scientists and medical practitioners interested in discovering new studies that underscore the importance of bile acids in ameliorating and impeding the progression of disorders. Furthermore, it opens avenues for previously overlooked bile acid-based therapies.

Farnesoid X receptor: From Structure to Function and Its Pharmacology in Liver Fibrosis

The farnesoid X receptor (FXR), a ligand-activated transcription factor, plays a crucial role in regulating bile acid metabolism within the enterohepatic circulation. Beyond its involvement in metabolic disorders and immune imbalances affecting various tissues, FXR is implicated in microbiota modulation, gut-to-brain communication, and liver disease. The liver, as a pivotal metabolic and detoxification organ, is susceptible to damage from factors such as alcohol, viruses, drugs, and high-fat diets. Chronic or recurrent liver injury can culminate in liver fibrosis, which, if left untreated, may progress to cirrhosis and even liver cancer, posing significant health risks. However, therapeutic options for liver fibrosis remain limited in terms of FDA-approved drugs. Recent insights into the structure of FXR, coupled with animal and clinical investigations, have shed light on its potential pharmacological role in hepatic fibrosis. Progress has been achieved in both fundamental research and clinical applications. This review critically examines recent advancements in FXR research, highlighting challenges and potential mechanisms underlying its role in liver fibrosis treatment.

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.

Sarmentol H derived from Sedum sarmentosum Bunge directly targets FXR to mitigate cholestasis by recruiting SRC-1

BACKGROUND

Farnesoid X receptor (FXR) is a vital receptor for bile acids and plays an important role in the treatment of cholestatic liver disease. In addition to traditional bile acid-based steroidal agonists, synthetic alkaloids are the most commonly reported non-steroidal FXR agonists. Sarmentol H is a nor-sesquiterpenoid obtained from Sedum sarmentosum Bunge, and in vitro screening experiments have shown that it might be related to the regulation of the FXR pathway in a previous study.

PURPOSE

To investigate the therapeutic effects of sarmentol H on cholestasis and to determine whether sarmentol H directly targets FXR to mitigate cholestasis. Furthermore, this study aimed to explore the key amino acid residues involved in the binding of sarmentol H to FXR through site-directed mutagenesis.

METHODS

An intrahepatic cholestasis mouse model was established to investigate the therapeutic effects of sarmentol H on cholestasis. In vitro experiments, including Co-Ip and FXR-EcRE-Luc assays, were performed to assess whether sarmentol H activates FXR by recruiting the receptor coactivator SRC1. CETSA, SIP, DARTS, and ITC were used to determine the binding of sarmentol H to FXR protein. The key amino acid residues for sarmentol H binding to FXR were analyzed by molecular docking and site-directed mutagenesis. Finally, we conducted in vivo experiments on wild-type and Fxr-/- mice to further validate the anticholestatic target of sarmentol H.

RESULTS

Sarmentol H had significant ameliorative effects on the pathological conditions of cholestatic mice induced with ANIT. In vitro experiments suggested that it is capable of activating FXR and regulating downstream signaling pathways by recruiting SRC1. The target validation experiments showed that sarmentol H had the ability to bind to FXR as a ligand (KD = 2.55 μmol/L) and enhance the stability of its spatial structure. Moreover, site-directed mutagenesis revealed that THR292 and TYR365 were key binding sites for sarmentol H and FXR. Furthermore, knockout of the Fxr gene resulted in a significantly higher degree of ANIT-induced cholestatic liver injury than that in wild-type cholestatic mice, and the amelioration of cholestasis or regulatory effects on FXR downstream genes by sarmentol H also disappeared in Fxr-/- cholestatic mice.

CONCLUSION

Sarmentol H is an FXR agonist. This is the first study to show that it exerts a significant therapeutic effect on cholestatic mice, and can directly bind to FXR and activate it by recruiting the coactivator SRC1.

New advances in drug development for metabolic dysfunction-associated diseases and alcohol-associated liver disease

Metabolic disorders are currently threatening public health worldwide. Discovering new targets and developing promising drugs will reduce the global metabolic-related disease burden. Metabolic disorders primarily consist of lipid and glucose metabolic disorders. Specifically, metabolic dysfunction-associated steatosis liver disease (MASLD) and alcohol-associated liver disease (ALD) are two representative lipid metabolism disorders, while diabetes mellitus is a typical glucose metabolism disorder. In this review, we aimed to summarize the new drug candidates with promising efficacy identified in clinical trials for these diseases. These drug candidates may provide alternatives for patients with metabolic disorders and advance the progress of drug discovery for the large disease burden.

Emerging targets for therapy in ALD: Lessons from NASH

Alcohol-associated liver disease due to harmful alcohol use and NAFLD associated with metabolic syndrome are the 2 most common liver diseases worldwide. Control of respective risk factors is the cornerstone in the long-term management of these diseases. Furthermore, there are no effective therapies. Both diseases are characterized by metabolic derangements; thus, the focus of this review was to broaden our understanding of metabolic targets investigated in NAFLD, and how these can be applied to alcohol-associated liver disease. Conserved pathogenic pathways such as dysregulated lipid metabolism, cell death pathways including apoptosis and activation of innate immune cells, and stellate cells mediate both alcohol and NAFLDs, resulting in histological abnormalities of steatosis, inflammation, fibrosis, and cirrhosis. However, pathways such as gut microbiome changes, glucose metabolism and insulin resistance, inflammatory signaling, and microRNA abnormalities are distinct in these 2 diseases. In this review article, we describe conserved and distinct pathogenic pathways highlighting therapeutic targets that may be of potential in both diseases and those that are unique to each disease.

Efficacy of pharmacologic interventions on magnetic resonance imaging biomarkers in patients with nonalcoholic fatty liver disease: systematic review and network meta-analysis

BACKGROUND AND AIM

Several agents are under investigation for nonalcoholic fatty liver disease (NAFLD). We assessed the comparative efficacy of pharmacologic interventions for patients with NAFLD focusing on magnetic resonance imaging (MRI) biomarkers.

METHODS

We searched Medline, Embase, and CENTRAL. We included randomized controlled trials of more than 12 weeks of intervention that recruited patients with biopsy-confirmed or MRI-confirmed NAFLD and assessed the efficacy of interventions on liver fat content (LFC) and fibrosis by means of MRI. We performed random-effects frequentist network meta-analyses and assessed confidence in our estimates using the CINeMA (Confidence in Network Meta-Analysis) approach.

RESULTS

We included 47 trials (8583 patients). Versus placebo, thiazolidinediones were the most efficacious for the absolute change in LFC, followed by vitamin E, fibroblast growth factor (FGF) analogs, and glucagon-like peptide-1 receptor agonists (GLP-1 RAs) with mean differences ranging from -7.46% (95% confidence interval [-11.0, -3.9]) to -4.36% (-7.2, -1.5). No differences between drug classes were evident. Patients receiving GLP-1 RAs or glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RAs were more likely to achieve ≥30% relative reduction in LFC. Among agents, efruxifermin produced the largest reduction in LFC compared to placebo [-13.5% (-18.5, -8.5)], followed by pioglitazone, while being superior to most interventions. The effect of interventions on magnetic resonance elastography assessed fibrosis was small and insignificant. The confidence in our estimates was low to very low.

CONCLUSIONS

Several drug classes may reduce LFC in patients with NAFLD without a significant effect on fibrosis; nevertheless, trial duration was small, and confidence in the effect estimates was low.

Immunology of bile acids regulated receptors

Bile acids are steroids formed at the interface of host metabolism and intestinal microbiota. While primary bile acids are generated in the liver from cholesterol metabolism, secondary bile acids represent the products of microbial enzymes. Close to 100 different enzymatic modifications of bile acids structures occur in the human intestine and clinically guided metagenomic and metabolomic analyses have led to the identification of an extraordinary number of novel metabolites. These chemical mediators make an essential contribution to the composition and function of the postbiota, participating to the bidirectional communications of the intestinal microbiota with the host and contributing to the architecture of intestinal-liver and -brain and -endocrine axes. Bile acids exert their function by binding to a group of cell membrane and nuclear receptors collectively known as bile acid-regulated receptors (BARRs), expressed in monocytes, tissue-resident macrophages, CD4+ T effector cells, including Th17, T regulatory cells, dendritic cells and type 3 of intestinal lymphoid cells and NKT cells, highlighting their role in immune regulation. In this review we report on how bile acids and their metabolitesmodulate the immune system in inflammations and cancers and could be exploiting for developing novel therapeutic approaches in these disorders.

Oligonucleotide therapies for nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) represents a severe disease subtype of nonalcoholic fatty liver disease (NAFLD) that is thought to be highly associated with systemic metabolic abnormalities. It is characterized by a series of substantial liver damage, including hepatocellular steatosis, inflammation, and fibrosis. The end stage of NASH, in some cases, may result in cirrhosis and hepatocellular carcinoma (HCC). Nowadays a large number of investigations are actively under way to test various therapeutic strategies, including emerging oligonucleotide drugs (e.g., antisense oligonucleotide, small interfering RNA, microRNA, mimic/inhibitor RNA, and small activating RNA) that have shown high potential in treating this fatal liver disease. This article systematically reviews the pathogenesis of NASH/NAFLD, the promising druggable targets proven by current studies in chemical compounds or biological drug development, and the feasibility and limitations of oligonucleotide-based therapeutic approaches under clinical or pre-clinical studies.

Evaluation of the Effects of Meal Type and Acid-Reducing Agents on the Pharmacokinetics of Cilofexor, a Selective Nonsteroidal Farnesoid X Receptor Agonist

Cilofexor is a nonsteroidal farnesoid X receptor agonist being developed in combination with firsocostat/semaglutide for the treatment of nonalcoholic steatohepatitis. This phase 1 study evaluated the effects of food and acid-reducing agents (ARAs) on the pharmacokinetics of cilofexor (100- or 30-mg fixed-dose combination with firsocostat) in healthy participants. Cohorts 1 (n = 20, 100 mg) and 2 (n = 30, 30 mg) followed a 3-period, 2-sequence crossover design and evaluated effects of light-fat and high-fat meals. Cohort 3 (n = 30, 100 mg fasting) followed a 2-period, 2-sequence crossover design and evaluated the effects of a 40-mg single dose of famotidine. Cohort 4 (n = 18, 100 mg) followed a 3-period, 2-sequence crossover design and evaluated the effects of a 40-mg once-daily regimen of omeprazole administered under fasting conditions or following a light-fat meal. Administration with light-fat or high-fat meals resulted in no change and an ∼35% reduction in cilofexor AUC, respectively, relative to the fasting conditions. Under fasting conditions, famotidine increased cilofexor AUC by 3.2-fold and Cmax by 6.1-fold, while omeprazole increased cilofexor AUC by 3.1-fold and Cmax by 4.8-fold. With a low-fat meal, omeprazole increased cilofexor exposure to a lesser extent (Cmax 2.5-fold, AUC 2.1-fold) than fasting conditions. This study suggests that caution should be exercised when cilofexor is administered with ARAs under fed conditions; coadministration of cilofexor (100 or 30 mg) with ARAs under fasting conditions is not recommended with the current clinical trial formulations.

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.

Mapping of mitogen and metabolic sensitivity in organoids defines requirements for human hepatocyte growth

Mechanisms underlying human hepatocyte growth in development and regeneration are incompletely understood. In vitro, human fetal hepatocytes (FH) can be robustly grown as organoids, while adult primary human hepatocyte (PHH) organoids remain difficult to expand, suggesting different growth requirements between fetal and adult hepatocytes. Here, we characterize hepatocyte organoid outgrowth using temporal transcriptomic and phenotypic approaches. FHs initiate reciprocal transcriptional programs involving increased proliferation and repressed lipid metabolism upon initiation of organoid growth. We exploit these insights to design maturation conditions for FH organoids, resulting in acquisition of mature hepatocyte morphological traits and increased expression of functional markers. During PHH organoid outgrowth in the same culture condition as for FHs, the adult transcriptomes initially mimic the fetal transcriptomic signatures, but PHHs rapidly acquire disbalanced proliferation-lipid metabolism dynamics, resulting in steatosis and halted organoid growth. IL6 supplementation, as emerged from the fetal dataset, and simultaneous activation of the metabolic regulator FXR, prevents steatosis and promotes PHH proliferation, resulting in improved expansion of the derived organoids. Single-cell RNA sequencing analyses reveal preservation of their fetal and adult hepatocyte identities in the respective organoid cultures. Our findings uncover mitogen requirements and metabolic differences determining proliferation of hepatocytes changing from development to adulthood.

Steatotic Liver Disease: Pathophysiology and Emerging Pharmacotherapies

Steatotic liver disease (SLD) displays a dynamic and complex disease phenotype. Consequently, the metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) therapeutic pipeline is expanding rapidly and in multiple directions. In parallel, noninvasive tools for diagnosing and monitoring responses to therapeutic interventions are being studied, and clinically feasible findings are being explored as primary outcomes in interventional trials. The realization that distinct subgroups exist under the umbrella of SLD should guide more precise and personalized treatment recommendations and facilitate advancements in pharmacotherapeutics. This review summarizes recent updates of pathophysiology-based nomenclature and outlines both effective pharmacotherapeutics and those in the pipeline for MASLD/MASH, detailing their mode of action and the current status of phase 2 and 3 clinical trials. Of the extensive arsenal of pharmacotherapeutics in the MASLD/MASH pipeline, several have been rejected, whereas other, mainly monotherapy options, have shown only marginal benefits and are now being tested as part of combination therapies, yet others are still in development as monotherapies. Although the Food and Drug Administration (FDA) has recently approved resmetirom, additional therapeutic approaches in development will ideally target MASH and fibrosis while improving cardiometabolic risk factors. Due to the urgent need for the development of novel therapeutic strategies and the potential availability of safety and tolerability data, repurposing existing and approved drugs is an appealing option. Finally, it is essential to highlight that SLD and, by extension, MASLD should be recognized and approached as a systemic disease affecting multiple organs, with the vigorous implementation of interdisciplinary and coordinated action plans. SIGNIFICANCE STATEMENT: Steatotic liver disease (SLD), including metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis, is the most prevalent chronic liver condition, affecting more than one-fourth of the global population. This review aims to provide the most recent information regarding SLD pathophysiology, diagnosis, and management according to the latest advancements in the guidelines and clinical trials. Collectively, it is hoped that the information provided furthers the understanding of the current state of SLD with direct clinical implications and stimulates research initiatives.

Bile acid and nonalcoholic steatohepatitis: Molecular insights and therapeutic targets

BACKGROUND

Nonalcoholic steatohepatitis (NASH) has been the second most common cause of liver transplantation in the United States. To date, NASH pathogenesis has not been fully elucidated but is multifactorial, involving insulin resistance, obesity, metabolic disorders, diet, dysbiosis, and gene polymorphism. An effective and approved therapy for NASH has also not been established. Bile acid is long known to have physiological detergent function in emulsifying and absorbing lipids and lipid-soluble molecules within the intestinal lumen. With more and more in-depth understandings of bile acid, it has been deemed to be a pivotal signaling molecule, which is capable of regulating lipid and glucose metabolism, liver inflammation, and fibrosis. In recent years, a plethora of studies have delineated that disrupted bile acid homeostasis is intimately correlated with NASH disease severity.

AIMS

The review aims to clarify the role of bile acid in hepatic lipid and glucose metabolism, liver inflammation, as well as liver fibrosis, and discusses the safety and efficacy of some pharmacological agents targeting bile acid and its associated pathways for NASH.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bile acid has a salutary effect on hepatic metabolic disorders, which can ameliorate liver fat accumulation and insulin resistance mainly through activating Takeda G-protein coupled receptor 5 and farnesoid X receptor. Moreover, bile acid also exerts anti-inflammation and anti-fibrosis properties. Furthermore, bile acid has great potential in nonalcoholic liver disease stratification and treatment of NASH.

Navigating the liver landscape: upcoming pharmacotherapies for primary sclerosing cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a bile duct disorder characterized by ductular reaction, hepatic inflammation, and liver fibrosis. The pathogenesis of PSC is still undefined, and treatment options for patients are limited. Previous clinical trials evaluated drug candidates targeting various cellular functions and pathways, such as bile acid signaling and absorption, gut bacteria and permeability, and lipid metabolisms. However, most of phase III clinical trials for PSC were disappointing, except vancomycin therapy, and there are still no established medications for PSC with efficacy and safety confirmed by phase IV clinical trials.

AREAS COVERED

This review summarizes the currently ongoing or completed clinical studies for PSC, which are phase II or further, and discusses therapeutic targets and strategies, limitations, and future directions and possibilities of PSC treatments. A literature search was conducted in PubMed and ClinicalTrials.gov utilizing the combination of the searched term 'primary sclerosing cholangitis' with other keywords, such as 'clinical trials,' 'antibiotics,' or drug names. Clinical trials at phase II or further were included for consideration.

EXPERT OPINION

Only vancomycin demonstrated promising therapeutic effects in the phase III clinical trial. Other drug candidates showed futility or inconsistent results, and the search for novel PSC treatments is still ongoing.

Incretin-based investigational therapies for the treatment of MASLD/MASH

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is the most common form of chronic liver disease. It exists as either simple steatosis or its more progressive form, metabolic dysfunction-associated steatohepatitis (MASH), formerly, non-alcoholic steatohepatitis (NASH). The global prevalence of MASLD is estimated to be 32% among adults and is projected to continue to rise with increasing rates of obesity, type 2 diabetes, and metabolic syndrome. While simple steatosis is often considered benign and reversible, MASH is progressive, potentially leading to the development of cirrhosis, liver failure, and hepatocellular carcinoma. Treatment of MASH is therefore directed at slowing, stopping, or reversing the progression of disease. Evidence points to improved liver histology with therapies that result in sustained body weight reduction. Incretin-based molecules, such as glucagon-like peptide-1 receptor agonists (GLP-1 RAs), alone or in combination with glucose-dependent insulinotropic polypeptide (GIP) and/or glucagon receptor agonists, have shown benefit here, and several are under investigation for MASLD/MASH treatment. In this review, we discuss current published data on GLP-1, GIP/GLP-1, GLP-1/glucagon, and GLP-1/GIP/glucagon RAs in MASLD/MASH, focusing on their efficacy on liver histology, liver fat, and MASH biomarkers.

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

Increased hepatoprotective effects of the novel farnesoid X receptor agonist INT-787 versus obeticholic acid in a mouse model of nonalcoholic steatohepatitis

The nuclear farnesoid X receptor (FXR), a master regulator of bile acid and metabolic homeostasis, is a key target for treatment of nonalcoholic steatohepatitis (NASH). This study compared efficacy of FXR agonists obeticholic acid (OCA) and INT-787 by liver histopathology, plasma biomarkers of liver damage, and hepatic gene expression profiles in the Amylin liver NASH (AMLN) diet-induced and biopsy-confirmed Lepob/ob mouse model of NASH. Lepob/ob mice were fed the AMLN diet for 12 weeks before liver biopsy and subsequent treatment with vehicle, OCA, or INT-787 for 8 weeks. Hepatic steatosis, inflammation, and fibrosis (liver lipids, galectin-3, and collagen 1a1 [Col1a1], respectively), as well as plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, were assessed. Hepatic gene expression was assessed in Lepob/ob mice that were fed the AMLN diet for 14 weeks then treated with vehicle, OCA, or INT-787 for 2 weeks. INT-787, which is equipotent to OCA but more hydrophilic, significantly reduced liver lipids, galectin-3, and Col1a1 compared with vehicle, and to a greater extent than OCA. INT-787 significantly reduced plasma ALT and AST levels, whereas OCA did not. INT-787 modulated a substantially greater number of genes associated with FXR signaling, lipid metabolism, and stellate cell activation relative to OCA in hepatic tissue. These findings demonstrate greater efficacy of INT-787 treatment compared with OCA in improving liver histopathology, decreasing liver enzyme levels, and enhancing gene regulation, suggesting superior clinical potential of INT-787 for the treatment of NASH and other chronic liver diseases.