The fatty acid-bile acid conjugate Aramchol reduces liver fat content in patients with nonalcoholic fatty liver disease

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.

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.

Aramchol improves hepatic fibrosis in metabolic dysfunction-associated steatohepatitis: Results of multimodality assessment using both conventional and digital pathology

BACKGROUND AND AIMS

Antifibrotic trials rely on conventional pathology despite recognized limitations. We compared single-fiber digital image analysis with conventional pathology to quantify the antifibrotic effect of Aramchol, a stearoyl-CoA desaturase 1 inhibitor in development for metabolic dysfunction-associated steatohepatitis.

APPROACH AND RESULTS

Fifty-one patients with metabolic dysfunction-associated steatohepatitis enrolled in the open-label part of the ARMOR trial received Aramchol 300 mg BID and had paired pre-post treatment liver biopsies scored by consensus among 3 hepatopathologists, and separately assessed by a digital image analysis platform (PharmaNest) that generates a continuous phenotypic Fibrosis Composite Severity (Ph-FCS) score. Fibrosis improvement was defined as: ≥1 NASH Clinical Research Network (NASH-CRN) stage reduction; "improved" by ranked pair assessment; reduction in Ph-FCS ("any" for ≥0.3 absolute reduction and "substantial" for ≥25% relative reduction). Fibrosis improved in 31% of patients (NASH-CRN), 51% (ranked pair assessment), 74.5% (any Ph-FCS reduction), and 41% (substantial Ph-FCS reduction). Most patients with stable fibrosis by NASH-CRN or ranked pair assessment had a Ph-FCS reduction (a third with substantial reduction). Fibrosis improvement increased with treatment duration: 25% for <48 weeks versus 39% for ≥48 weeks by NASH-CRN; 43% versus 61% by ranked pair assessment, mean Ph-FCS reduction -0.54 (SD: 1.22) versus -1.72 (SD: 1.02); Ph-FCS reduction (any in 54% vs. 100%, substantial in 21% vs. 65%). The antifibrotic effect of Aramchol was corroborated by reductions in liver stiffness, Pro-C3, and enhanced liver fibrosis. Changes in Ph-FCS were positively correlated with changes in liver stiffness.

CONCLUSIONS

Continuous fibrosis scores generated in antifibrotic trials by digital image analysis quantify antifibrotic effects with greater sensitivity and a larger dynamic range than conventional pathology.

Exploring the potential of drug repurposing for liver diseases: A comprehensive study

Drug repurposing involves the investigation of existing drugs for new indications. It offers a great opportunity to quickly identify a new drug candidate at a lower cost than novel discovery and development. Despite the importance and potential role of drug repurposing, there is no specific definition that healthcare providers and the World Health Organization credit. Unfortunately, many similar and interchangeable concepts are being used in the literature, making it difficult to collect and analyze uniform data on repurposed drugs. This research was conducted based on understanding general criteria for drug repurposing, concentrating on liver diseases. Many drugs have been investigated for their effect on liver diseases even though they were originally approved (or on their way to being approved) for other diseases. Some of the hypotheses for drug repurposing were first captured from the literature and then processed further to test the hypothesis. Recently, with the revolution in bioinformatics techniques, scientists have started to use drug libraries and computer systems that can analyze hundreds of drugs to give a short list of candidates to be analyzed pharmacologically. However, this study revealed that drug repurposing is a potential aid that may help deal with liver diseases. It provides available or under-investigated drugs that could help treat hepatitis, liver cirrhosis, Wilson disease, liver cancer, and fatty liver. However, many further studies are needed to ensure the efficacy of these drugs on a large scale.

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.

Emerging drugs for the treatment of hepatic fibrosis on nonalcoholic steatohepatitis

INTRODUCTION

Approved drug therapies for nonalcoholic steatohepatitis (NASH) are lacking, for which various agents are currently being tested in clinical trials. Effective drugs for liver fibrosis, the factor most associated with prognosis in NASH, are important.

AREAS COVERED

This study reviewed the treatment of NASH with a focus on the effects of existing drugs and new drugs on liver fibrosis.

EXPERT OPINION

Considering the complex pathophysiology of fibrosis in NASH, drug therapy may target multiple pathways. The method of assessing fibrosis is important when considering treatment for liver fibrosis in NASH. The Food and Drug Administration considers an important fibrosis endpoint to be histological improvement in at least one fibrosis stage while preventing worsening of fatty hepatitis. To obtain approval as a drug for NASH, efficacy needs to be demonstrated on endpoints such as liver-related events and myocardial infarction. Among the current therapeutic agents for NASH, thiazolidinedione, sodium-glucose co-transporter 2, and selective peroxisome proliferator-activated receptors α modulator have been reported to be effective against fibrosis, although further evidence is required. The effects of pan-peroxisome proliferator-activated receptors, obeticholic acid, and fibroblast growth factor-21 analogs on liver fibrosis in the development stage therapeutics for NASH are of particular interest.

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.

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.

The potential of the nutraceutical berberine in the treatment of hepatocellular carcinoma and other liver diseases such as NAFLD and NASH

Hepatocellular carcinoma (HCC) is a common cancer which unfortunately has poor outcomes. Common anti-cancer treatments such as chemotherapy and targeted therapy have not increased patient survival significantly. A common treatment for HCC patients is transplantation, however, it has limitations and complications. Novel approaches are necessary to more effectively treat HCC patients. Berberine (BBR) is a nutraceutical derived from various fruits and trees, which has been used for centuries in traditional medicine to treat various diseases such as diabetes and inflammation. More recently, the anti-proliferation effects of BBR have been investigated in the treatment of patients with various cancers, especially colorectal cancer, and in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this review, we will focus on studies with BBR in liver diseases.

Advancements in metabolic-associated steatotic liver disease research: Diagnostics, small molecule developments, and future directions

Metabolic (dysfunction)-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease, is a growing global health concern with no approved pharmacological treatments. At the same time, there are no standard methods to definitively screen for the presence of MASLD because of its progressive nature and symptomatic commonality with other disorders. Recent advances in molecular understanding of MASLD pathophysiology have intensified research on development of new drug molecules, repurposing of existing drugs approved for other indications, and an educated use of dietary supplements for its treatment and prophylaxis. This review focused on depicting the latest advancements in MASLD research related to small molecule development for prophylaxis or treatment and diagnosis, with emphasis on mechanistic basis at the molecular level.

Emerging therapies for MASLD and their impact on plasma lipids

Metabolic-dysfunction associated steatotic liver disease (MASLD) affects 1 out of every 3 individuals in the adult population and the disease prevalence is predicted to increase worldwide. Patients with MASLD are also burdened by cardiovascular disease, which is the leading cause of mortality in this population. Complex metabolic derangements such as insulin resistance and atherogenic dyslipidemia affect patients with MASLD. In patients with MASLD, treatment such as pharmacotherapy may be best directed towards improving the adverse concomitant metabolic disorders associated with MASLD, particularly the ones that may contribute to MASLD. Herein, we discuss conventional therapies that target cardiometabolic risk factors which have the potential to improve hepatic injury, and summarize emerging therapies that target hepatic receptors, fibrosis, and fatty acid oxidation in patients with MASLD. Given the relationship between hepatic injury which leads to MASLD, insulin resistance, and ultimately atherogenic dyslipidemia our review uniquely delves into the effects of conventional and emerging therapies for MASLD on plasma lipid parameters.

Pharmacologic inhibition of lipogenesis for the treatment of NAFLD

The hepatic accumulation of excess triglycerides is a seminal event in the initiation and progression of non-alcoholic fatty liver disease (NAFLD). Hepatic steatosis occurs when the hepatic accrual of fatty acids from the plasma and de novo lipogenesis (DNL) is no longer balanced by rates of fatty acid oxidation and secretion of very low-density lipoprotein-triglycerides. Accumulating data indicate that increased rates of DNL are central to the development of hepatic steatosis in NAFLD. Whereas the main drivers in NAFLD are transcriptional, owing to both hyperinsulinemia and hyperglycaemia, the effectors of DNL are a series of well-characterised enzymes. Several have proven amenable to pharmacologic inhibition or oligonucleotide-mediated knockdown, with lead compounds showing liver fat-lowering efficacy in phase II clinical trials. In humans with NAFLD, percent reductions in liver fat have closely mirrored percent inhibition of DNL, thereby affirming the critical contributions of DNL to NAFLD pathogenesis. The safety profiles of these compounds have so far been encouraging. It is anticipated that inhibitors of DNL, when administered alone or in combination with other therapeutic agents, will become important agents in the management of human NAFLD.

SCD1 is the critical signaling hub to mediate metabolic diseases: Mechanism and the development of its inhibitors

Metabolic diseases, featured with dysregulated energy homeostasis, have become major global health challenges. Patients with metabolic diseases have high probability to manifest multiple complications in lipid metabolism, e.g. obesity, insulin resistance and fatty liver. Therefore, targeting the hub genes in lipid metabolism may systemically ameliorate the metabolic diseases, along with the complications. Stearoyl-CoA desaturase 1(SCD1) is a key enzyme that desaturates the saturated fatty acids (SFAs) derived from de novo lipogenesis or diet to generate monounsaturated fatty acids (MUFAs). SCD1 maintains the metabolic and tissue homeostasis by responding to, and integrating the multiple layers of endogenous stimuli, which is mediated by the synthesized MUFAs. It critically regulates a myriad of physiological processes, including energy homeostasis, development, autophagy, tumorigenesis and inflammation. Aberrant transcriptional and epigenetic activation of SCD1 regulates AMPK/ACC, SIRT1/PGC1α, NcDase/Wnt, etc, and causes aberrant lipid accumulation, thereby promoting the progression of obesity, non-alcoholic fatty liver, diabetes and cancer. This review critically assesses the integrative mechanisms of the (patho)physiological functions of SCD1 in metabolic homeostasis, inflammation and autophagy. For translational perspective, potent SCD1 inhibitors have been developed to treat various types of cancer. We thus discuss the multidisciplinary advances that greatly accelerate the development of SCD1 new inhibitors. In conclusion, besides cancer treatment, SCD1 may serve as the promising target to combat multiple metabolic complications simultaneously.

Metabolic dysfunction-associated steatotic liver disease and the heart

The prevalence and severity of metabolic dysfunction-associated steatotic liver disease (MASLD) are increasing. Physicians who treat patients with MASLD may acknowledge the strong coincidence with cardiometabolic disease, including atherosclerotic cardiovascular disease (asCVD). This raises questions on co-occurrence, causality, and the need for screening and multidisciplinary care for MASLD in patients with asCVD, and vice versa. Here, we review the interrelations of MASLD and heart disease and formulate answers to these matters. Epidemiological studies scoring proxies for atherosclerosis and actual cardiovascular events indicate increased atherosclerosis in patients with MASLD, yet no increased risk of asCVD mortality. MASLD and asCVD share common drivers: obesity, insulin resistance and type 2 diabetes mellitus (T2DM), smoking, hypertension, and sleep apnea syndrome. In addition, Mendelian randomization studies support that MASLD may cause atherosclerosis through mixed hyperlipidemia, while such evidence is lacking for liver-derived procoagulant factors. In the more advanced fibrotic stages, MASLD may contribute to heart failure with preserved ejection fraction by reduced filling of the right ventricle, which may induce fatigue upon exertion, often mentioned by patients with MASLD. Some evidence points to an association between MASLD and cardiac arrhythmias. Regarding treatment and given the strong co-occurrence of MASLD and asCVD, pharmacotherapy in development for advanced stages of MASLD would ideally also reduce cardiovascular events, as has been demonstrated for T2DM treatments. Given the common drivers, potential causal factors and especially given the increased rate of cardiovascular events, comprehensive cardiometabolic risk management is warranted in patients with MASLD, preferably in a multidisciplinary approach.

MASLD treatment-a shift in the paradigm is imminent

MASLD prevalence is growing towards the leading cause of end-stage liver disease. Up to today, the most effective treatment is weight loss. Weight loss interventions are moving from lifestyle changes to bariatric surgery or endoscopy, and, more recently, to a new wave of anti-obesity drugs that can compete with bariatric surgery. Liver-targeted therapy is a necessity for those patients who already present liver fibrosis. The field is moving fast, and in the near future, we will testify to a disruptive change in MASLD treatment, similar to the paradigm-shift that occurred for hepatitis C almost one decade ago with direct antiviral agents.

Lysophosphatidic acid receptor 1 antagonist (EPGN2154) causes regression of NASH in preclinical NASH models

BACKGROUND

NASH causes a tremendous health care burden in the United States. A glucagon-like peptide-1 agonist, semaglutide (Sema), treatment resulted in hepatic steatosis reduction in clinical trials of NASH. Lysophosphatidic acid receptor 1 antagonists are known to have antifibrotic effects in several organs. We tested Sema and a novel lysophosphatidic acid receptor 1 antagonist, EPGN2154, individually and in combination to evaluate their efficacy for NASH remission in preclinical models.

METHODS

In the present study, we used (1) C57Bl6/J wild-type mice fed on a high-fat, high-carbohydrate (HFHC) diet for 16 weeks and (2) leptin-deficient mice (ob/ob) fed on an Amylin liver NASH diet for 16 weeks. After 16 weeks, the mice were randomly distributed in equal numbers in (1) no-drug, (2) EPGN2154, (3) Sema, and (4) EPGN2154+Sema treatment groups for 8 additional weeks at a dosage of 10 mg/kg body weight for EPGN2154 (oral gavage, 5 days a week) and 6.17 μg/kg body weight of Sema (subcutaneous injection every alternate day, 3 days a week).

RESULTS

In the wild-type-high-fat, high-carbohydrate model, we observed the most body weight loss in the EPGN2154+Sema combination group compared to the other treatment groups. All groups led to a significant reduction in alanine transaminase levels when compared to high-fat, high-carbohydrate-fed wild type. However, no significant difference in alanine transaminase levels was observed among the treatment groups. In the ob/ob mice study, Sema did not cause body weight loss. Moreover, the EPGN2154 and the combination groups had a lower NAFLD Activity Score and incidence of advanced-stage hepatic fibrosis than the Sema group.

CONCLUSIONS

EPGN2154 demonstrated a hepato-protective effect independent of body weight loss in preclinical NASH models.

Unmasking the enigma of lipid metabolism in metabolic dysfunction-associated steatotic liver disease: from mechanism to the clinic

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly defined as non-alcoholic fatty liver disease (NAFLD), is a disorder marked by the excessive deposition of lipids in the liver, giving rise to a spectrum of liver pathologies encompassing steatohepatitis, fibrosis/cirrhosis, and hepatocellular carcinoma. Despite the alarming increase in its prevalence, the US Food and Drug Administration has yet to approve effective pharmacological therapeutics for clinical use. MASLD is characterized by the accretion of lipids within the hepatic system, arising from a disarray in lipid provision (whether through the absorption of circulating lipids or de novo lipogenesis) and lipid elimination (via free fatty acid oxidation or the secretion of triglyceride-rich lipoproteins). This disarray leads to the accumulation of lipotoxic substances, cellular pressure, damage, and fibrosis. Indeed, the regulation of the lipid metabolism pathway is intricate and multifaceted, involving a myriad of factors, such as membrane transport proteins, metabolic enzymes, and transcription factors. Here, we will review the existing literature on the key process of lipid metabolism in MASLD to understand the latest progress in this molecular mechanism. Notably, de novo lipogenesis and the roles of its two main transcription factors and other key metabolic enzymes are highlighted. Furthermore, we will delve into the realm of drug research, examining the recent progress made in understanding lipid metabolism in MASLD. Additionally, we will outline prospective avenues for future drug research on MASLD based on our unique perspectives.

Identification of novel SCD1 inhibitor alleviates nonalcoholic fatty liver disease: critical role of liver-adipose axis

Due to the complexity and incomplete understanding of the crosstalk between liver and adipose tissue, especially the processes of hepatic lipogenesis and adipogenic differentiation, there are currently no effective drugs for the treatment of nonalcoholic fatty liver disease (NAFLD). Stearoyl-coenzyme A desaturase 1 (SCD1), which is abundantly expressed in liver and adipose tissue, may mediate the cross-talk between liver and adipose tissue. Thus, it is essential to develop specific SCD1 inhibitors that target the liver-adipose axis. Herein, we identified a novel SCD1 inhibitor, E6446, through a high-throughput virtual screen. E6646 significantly inhibited adipogenic differentiation and hepatic lipogenesis via SCD1-ATF3 signaling. The SPR results showed that E6446 had a strong interaction ability with SCD1 (KD:4.61 μM). Additionally, E6646 significantly decreased hepatic steatosis, hepatic lipid droplet accumulation and insulin resistance in high-fat diet (HFD)-fed mice. Taken together, our findings not only suggest that E6446 can serve as a new, safe and highly effective anti-NAFLD agent for future clinical use but also provide a molecular basis for the future development of SCD1 inhibitors that inhibit both adipogenic differentiation and hepatic lipogenesis. Video Abstract.

The Crosstalk between Gut Microbiota and Bile Acids Promotes the Development of Non-Alcoholic Fatty Liver Disease

Recently the roles of gut microbiota are highly regarded in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). The intestinal bacteria regulate the metabolism of bile acids depending on bile salt hydrolase (BSH), 7-dehydroxylation, hydroxysteroid dehydrogenase (HSDH), or amide conjugation reaction, thus exerting effects on NAFLD development through bile acid receptors such as farnesoid X receptor (FXR), Takeda G-protein-coupled bile acid protein 5 (TGR5), and vitamin D receptor (VDR), which modulate nutrient metabolism and insulin sensitivity via interacting with downstream molecules. Reversely, the composition of gut microbiota is also affected by the level of bile acids in turn. We summarize the mutual regulation between the specific bacteria and bile acids in NAFLD and the latest clinical research based on microbiota and bile acids, which facilitate the development of novel treatment modalities in NAFLD.

Mitochondrial metabolic dysfunction and non-alcoholic fatty liver disease: new insights from pathogenic mechanisms to clinically targeted therapy

Metabolic dysfunction-associated fatty liver disease (MAFLD) is among the most widespread metabolic disease globally, and its associated complications including insulin resistance and diabetes have become threatening conditions for human health. Previous studies on non-alcoholic fatty liver disease (NAFLD) were focused on the liver's lipid metabolism. However, growing evidence suggests that mitochondrial metabolism is involved in the pathogenesis of NAFLD to varying degrees in several ways, for instance in cellular division, oxidative stress, autophagy, and mitochondrial quality control. Ultimately, liver function gradually declines as a result of mitochondrial dysfunction. The liver is unable to transfer the excess lipid droplets outside the liver. Therefore, how to regulate hepatic mitochondrial function to treat NAFLD has become the focus of current research. This review provides details about the intrinsic link of NAFLD with mitochondrial metabolism and the mechanisms by which mitochondrial dysfunctions contribute to NAFLD progression. Given the crucial role of mitochondrial metabolism in NAFLD progression, the application potential of multiple mitochondrial function improvement modalities (including physical exercise, diabetic medications, small molecule agonists targeting Sirt3, and mitochondria-specific antioxidants) in the treatment of NAFLD was evaluated hoping to provide new insights into NAFLD treatment.

Pharmacotherapies of NAFLD: updated opportunities based on metabolic intervention

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that is becoming increasingly prevalent, and it ranges from simple steatosis to cirrhosis. However, there is still a lack of pharmacotherapeutic strategies approved by the Food and Drug Administration, which results in a higher risk of death related to carcinoma and cardiovascular complications. Of note, it is well established that the pathogenesis of NAFLD is tightly associated with whole metabolic dysfunction. Thus, targeting interconnected metabolic conditions could present promising benefits to NAFLD, according to a number of clinical studies. Here, we summarize the metabolic characteristics of the development of NAFLD, including glucose metabolism, lipid metabolism and intestinal metabolism, and provide insight into pharmacological targets. In addition, we present updates on the progresses in the development of pharmacotherapeutic strategies based on metabolic intervention globally, which could lead to new opportunities for NAFLD drug development.

Lipidomics in pathogenesis, progression and treatment of nonalcoholic steatohepatitis (NASH): Recent advances

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease affecting up to 30% of the general adult population. NAFLD encompasses a histological spectrum ranging from pure steatosis to non-alcoholic steatohepatitis (NASH). NASH can progress to cirrhosis and is becoming the most common indication for liver transplantation, as a result of increasing disease prevalence and of the absence of approved treatments. Lipidomic readouts of liver blood and urine samples from experimental models and from NASH patients disclosed an abnormal lipid composition and metabolism. Collectively, these changes impair organelle function and promote cell damage, necro-inflammation and fibrosis, a condition termed lipotoxicity. We will discuss the lipid species and metabolic pathways leading to NASH development and progression to cirrhosis, as well as and those species that can contribute to inflammation resolution and fibrosis regression. We will also focus on emerging lipid-based therapeutic opportunities, including specialized proresolving lipid molecules and macrovesicles contributing to cell-to-cell communication and NASH pathophysiology.

Physiological and pathological roles of lipogenesis

Lipids are essential metabolites, which function as energy sources, structural components and signalling mediators. Most cells are able to convert carbohydrates into fatty acids, which are often converted into neutral lipids for storage in the form of lipid droplets. Accumulating evidence suggests that lipogenesis plays a crucial role not only in metabolic tissues for systemic energy homoeostasis but also in immune and nervous systems for their proliferation, differentiation and even pathophysiological roles. Thus, excessive or insufficient lipogenesis is closely associated with aberrations in lipid homoeostasis, potentially leading to pathological consequences, such as dyslipidaemia, diabetes, fatty liver, autoimmune diseases, neurodegenerative diseases and cancers. For systemic energy homoeostasis, multiple enzymes involved in lipogenesis are tightly controlled by transcriptional and post-translational modifications. In this Review, we discuss recent findings regarding the regulatory mechanisms, physiological roles and pathological importance of lipogenesis in multiple tissues such as adipose tissue and the liver, as well as the immune and nervous systems. Furthermore, we briefly introduce the therapeutic implications of lipogenesis modulation.

How far are we from an approved drug for non-alcoholic steatohepatitis?

INTRODUCTION

Metabolic associated fatty liver disease (MAFLD) previously known but still debatable, as non-alcoholic fatty liver disease (NAFLD) is one of the main causes of chronic liver disease and subsequent cirrhosis worldwide, accounting for around 30% of liver diseases. The change in its nomenclature has been brought about by the novel discoveries regarding its pathogenesis, in which metabolic dysfunction plays the most important role. It is widely known that for every disease, the treatment should always be targeted toward the underlying etiology and pathogenesis.

AREAS COVERED

MAFLD/NAFLD pathogenesis is heterogeneous, and includes multiple gene polymorphisms, presence of insulin resistance, as well as concomitant diseases that contribute to the disease onset and progression. As a result of this, even though lifestyle modification (owing to metabolic abnormalities) is the first line of treatment, multiple drugs have been tested to target each of the known pathways leading to MAFLD/NAFLD and progression of steatohepatitis. We aim to review the most relevant information regarding previous and ongoing research and recommendations regarding treatment of MAFLD/NAFLD.

EXPERT OPINION

Combination therapies associated to weight loss and exercise will be the optimal approach for these patients. It is important to evaluate each patient to select the specific combination according to patient characteristics.

Dysregulated Liver Metabolism and Polycystic Ovarian Syndrome

A significant fraction of couples around the world suffer from polycystic ovarian syndrome (PCOS), a disease defined by the characteristics of enhanced androgen synthesis in ovarian theca cells, hyperandrogenemia, and ovarian dysfunction in women. Most of the clinically observable symptoms and altered blood biomarker levels in the patients indicate metabolic dysregulation and adaptive changes as the key underlying mechanisms. Since the liver is the metabolic hub of the body and is involved in steroid-hormonal detoxification, pathological changes in the liver may contribute to female endocrine disruption, potentially through the liver-to-ovary axis. Of particular interest are hyperglycemic challenges and the consequent changes in liver-secretory protein(s) and insulin sensitivity affecting the maturation of ovarian follicles, potentially leading to female infertility. The purpose of this review is to provide insight into emerging metabolic mechanisms underlying PCOS as the primary culprit, which promote its incidence and aggravation. Additionally, this review aims to summarize medications and new potential therapeutic approaches for the disease.

Recent updates on targeting the molecular mediators of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming the most common disease worldwide in an era of rapid economic growth. NAFLD is a multifactorial disease, involving multiple genetic, metabolic, and environmental factors, and is closely associated with metabolic syndrome, obesity, and cardiovascular disease. NAFLD can be classified into nonalcoholic fatty liver disease (NAFL) and nonalcoholic steatohepatitis (NASH), which can both progress to cirrhosis and even hepatocellular carcinoma (HCC). Due to the enormous burden of NAFLD and its complications, no FDA-approved drugs for the treatment of NAFLD are on the market, and therapeutic targets and drug therapies are being actively investigated. In view of the various pathological mechanisms of NAFLD, numbers of preclinical studies and clinical trials have made rapid progress. This review mainly summarizes the most recently characterized mechanisms and therapeutic targets in each mechanism of NAFLD, focusing on the mechanism and application potential.

Immunometabolic factors contributing to obesity-linked hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major public health concern that is promoted by obesity and associated liver complications. Onset and progression of HCC in obesity is a multifactorial process involving complex interactions between the metabolic and immune system, in which chronic liver damage resulting from metabolic and inflammatory insults trigger carcinogenesis-promoting gene mutations and tumor metabolism. Moreover, cell growth and proliferation of the cancerous cell, after initiation, requires interactions between various immunological and metabolic pathways that provide stress defense of the cancer cell as well as strategic cell death escape mechanisms. The heterogenic nature of HCC in addition to the various metabolic risk factors underlying HCC development have led researchers to focus on examining metabolic pathways that may contribute to HCC development. In obesity-linked HCC, oncogene-induced modifications and metabolic pathways have been identified to support anabolic demands of the growing HCC cells and combat the concomitant cell stress, coinciding with altered utilization of signaling pathways and metabolic fuels involved in glucose metabolism, macromolecule synthesis, stress defense, and redox homeostasis. In this review, we discuss metabolic insults that can underlie the transition from steatosis to steatohepatitis and from steatohepatitis to HCC as well as aberrantly regulated immunometabolic pathways that enable cancer cells to survive and proliferate in the tumor microenvironment. We also discuss therapeutic modalities targeted at HCC prevention and regression. A full understanding of HCC-associated immunometabolic changes in obesity may contribute to clinical treatments that effectively target cancer metabolism.

The interplay between nonalcoholic fatty liver disease and atherosclerotic cardiovascular disease

Therapeutic approaches that lower circulating low-density lipoprotein (LDL)-cholesterol significantly reduced the burden of cardiovascular disease over the last decades. However, the persistent rise in the obesity epidemic is beginning to reverse this decline. Alongside obesity, the incidence of nonalcoholic fatty liver disease (NAFLD) has substantially increased in the last three decades. Currently, approximately one third of world population is affected by NAFLD. Notably, the presence of NAFLD and particularly its more severe form, nonalcoholic steatohepatitis (NASH), serves as an independent risk factor for atherosclerotic cardiovascular disease (ASCVD), thus, raising interest in the relationship between these two diseases. Importantly, ASCVD is the major cause of death in patients with NASH independent of traditional risk factors. Nevertheless, the pathophysiology linking NAFLD/NASH with ASCVD remains poorly understood. While dyslipidemia is a common risk factor underlying both diseases, therapies that lower circulating LDL-cholesterol are largely ineffective against NASH. While there are no approved pharmacological therapies for NASH, some of the most advanced drug candidates exacerbate atherogenic dyslipidemia, raising concerns regarding their adverse cardiovascular consequences. In this review, we address current gaps in our understanding of the mechanisms linking NAFLD/NASH and ASCVD, explore strategies to simultaneously model these diseases, evaluate emerging biomarkers that may be useful to diagnose the presence of both diseases, and discuss investigational approaches and ongoing clinical trials that potentially target both diseases.

Shedding light on non-alcoholic fatty liver disease: Pathogenesis, molecular mechanisms, models, and emerging therapeutics

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder globally impacting an estimated 25% of the population associated with severe consequences such as cirrhosis, hepatocellular carcinoma (HCC), and overall mortality. Fatty liver disease is triggered through multiple pathways, but the most prominent cause is either diabetes or obesity, or a combination of both. Therefore, hepatic glucose, insulin and fatty acid signaling becomes a dire need to understand which is well elaborated in this review. This review summarizes the popular two-hit pathogenesis of NAFLD, the molecular mechanisms underlying hepatic insulin resistance. As fatty liver disease gets advanced, it requires in-vitro as well as in-vivo models closer to disease progression in humans for better understanding the pathological state and identifying a novel therapeutic target. This review summarizes in-vitro (2D cell-culture/co-culture, 3D spheroid/organoid/liver-on-a-chip) models as well as in-vivo (genetically/dietary/chemically induced fatty liver disease) research models. Fatty liver disease research has gathered lots of attention recently since there is no FDA approved therapy available so far. However, there have been numerous promising targets to treat fatty liver disease including potential therapeutic targets under clinical trials are listed in this review.

Diagnostic and therapeutic strategies for non-alcoholic fatty liver disease

The global incidence rate of non-alcoholic fatty liver disease (NAFLD) is approximately 25%. With the global increase in obesity and its associated metabolic syndromes, NAFLD has become an important cause of chronic liver disease in many countries. Despite recent advances in pathogenesis, diagnosis, and therapeutics, there are still challenges in its treatment. In this review, we briefly describe diagnostic methods, therapeutic targets, and drugs related to NAFLD. In particular, we focus on evaluating carbohydrate and lipid metabolism, lipotoxicity, cell death, inflammation, and fibrosis as potential therapeutic targets for NAFLD. We also summarized the clinical research progress in terms of drug development and combination therapy, thereby providing references for NAFLD drug development.

Therapies for non-alcoholic fatty liver disease: A 2022 update

The incidence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing and lifestyle interventions to treat this disease by addressing the underlying metabolic syndrome are often limited. Many pharmacological interventions are being studied to slow or even reverse NAFLD progression. This review for hepatologists aims to provide an updated understanding of the pathogenesis of NAFLD, current recommended therapies, and the most promising treatment options that are currently under development.

Downregulation of hepatic lipopolysaccharide binding protein improves lipogenesis-induced liver lipid accumulation

Circulating lipopolysaccharide-binding protein (LBP) is increased in individuals with liver steatosis. We aimed to evaluate the possible impact of liver LBP downregulation using lipid nanoparticle-containing chemically modified LBP small interfering RNA (siRNA) (LNP-Lbp UNA-siRNA) on the development of fatty liver. Weekly LNP-Lbp UNA-siRNA was administered to mice fed a standard chow diet, a high-fat and high-sucrose diet, and a methionine- and choline-deficient diet (MCD). In mice fed a high-fat and high-sucrose diet, which displayed induced liver lipogenesis, LBP downregulation led to reduced liver lipid accumulation, lipogenesis (mainly stearoyl-coenzyme A desaturase 1 [Scd1]) and lipid peroxidation-associated oxidative stress markers. LNP-Lbp UNA-siRNA also resulted in significantly decreased blood glucose levels during an insulin tolerance test. In mice fed a standard chow diet or an MCD, in which liver lipogenesis was not induced or was inhibited (especially Scd1 mRNA), liver LBP downregulation did not impact on liver steatosis. The link between hepatocyte LBP and lipogenesis was further confirmed in palmitate-treated Hepa1-6 cells, in primary human hepatocytes, and in subjects with morbid obesity. Altogether, these data indicate that siRNA against liver Lbp mRNA constitutes a potential target therapy for obesity-associated fatty liver through the modulation of hepatic Scd1.

Bile acid metabolism and signaling, the microbiota, and metabolic disease

The diversity, composition, and function of the bacterial community inhabiting the human gastrointestinal tract contributes to host health through its role in producing energy or signaling molecules that regulate metabolic and immunologic functions. Bile acids are potent metabolic and immune signaling molecules synthesized from cholesterol in the liver and then transported to the intestine where they can undergo metabolism by gut bacteria. The combination of host- and microbiota-derived enzymatic activities contribute to the composition of the bile acid pool and thus there can be great diversity in bile acid composition that depends in part on the differences in the gut bacteria species. Bile acids can profoundly impact host metabolic and immunological functions by activating different bile acid receptors to regulate signaling pathways that control a broad range of complex symbiotic metabolic networks, including glucose, lipid, steroid and xenobiotic metabolism, and modulation of energy homeostasis. Disruption of bile acid signaling due to perturbation of the gut microbiota or dysregulation of the gut microbiota-host interaction is associated with the pathogenesis and progression of metabolic disorders. The metabolic and immunological roles of bile acids in human health have led to novel therapeutic approaches to manipulate the bile acid pool size, composition, and function by targeting one or multiple components of the microbiota-bile acid-bile acid receptor axis.

The contribution of the gut-liver axis to the immune signaling pathway of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the liver manifestation of metabolic syndrome and is the most common chronic liver disease in the world. The pathogenesis of NAFLD has not been fully clarified; it involves metabolic disturbances, inflammation, oxidative stress, and various forms of cell death. The “intestinal-liver axis” theory, developed in recent years, holds that there is a certain relationship between liver disease and the intestinal tract, and changes in intestinal flora are closely involved in the development of NAFLD. Many studies have found that the intestinal flora regulates the pathogenesis of NAFLD by affecting energy metabolism, inducing endotoxemia, producing endogenous ethanol, and regulating bile acid and choline metabolism. In this review, we highlighted the updated discoveries in intestinal flora dysregulation and their link to the pathogenesis mechanism of NAFLD and summarized potential treatments of NAFLD related to the gut microbiome.

Targeted therapeutics and novel signaling pathways in non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH)

Non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH) has become the leading cause of liver disease worldwide. NASH, an advanced form of NAFL, can be progressive and more susceptible to developing cirrhosis and hepatocellular carcinoma. Currently, lifestyle interventions are the most essential and effective strategies for preventing and controlling NAFL without the development of fibrosis. While there are still limited appropriate drugs specifically to treat NAFL/NASH, growing progress is being seen in elucidating the pathogenesis and identifying therapeutic targets. In this review, we discussed recent developments in etiology and prospective therapeutic targets, as well as pharmacological candidates in pre/clinical trials and patents, with a focus on diabetes, hepatic lipid metabolism, inflammation, and fibrosis. Importantly, growing evidence elucidates that the disruption of the gut-liver axis and microbe-derived metabolites drive the pathogenesis of NAFL/NASH. Extracellular vesicles (EVs) act as a signaling mediator, resulting in lipid accumulation, macrophage and hepatic stellate cell activation, further promoting inflammation and liver fibrosis progression during the development of NAFL/NASH. Targeting gut microbiota or EVs may serve as new strategies for the treatment of NAFL/NASH. Finally, other mechanisms, such as cell therapy and genetic approaches, also have enormous therapeutic potential. Incorporating drugs with different mechanisms and personalized medicine may improve the efficacy to better benefit patients with NAFL/NASH.

Impact of NAFLD and its pharmacotherapy on lipid profile and CVD

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide. Increasing evidence suggests that, in addition to traditional metabolic risk factors such as obesity, hypercholesterolemia, hypertension, diabetes mellitus, and insulin resistance (IR), nonalcoholic fatty liver disease (NAFLD) is an emerging driver of ASCVD via multiple mechanisms, mainly by disrupting lipid metabolism. The lack of pharmaceutical treatment has spurred substantial investment in the research and development of NAFLD drugs. However, many reagents with promising therapeutic potential for NAFLD also have considerable impacts on the circulating lipid profile. In this review, we first summarize the mechanisms linking lipid dysregulation in NAFLD to the progression of ASCVD. Importantly, we highlight the potential risks of/benefits to ASCVD conferred by NAFLD pharmaceutical treatments and discuss potential strategies and next-generation drugs for treating NAFLD without the unwanted side effects.

Breakthroughs in therapies for NASH and remaining challenges

Initially a condition that received limited recognition and whose clinical impact was controversial, non-alcoholic steatohepatitis (NASH) has become a leading cause of chronic liver disease. Although there are no approved therapies, major breakthroughs, which will be reviewed here, have paved the way for future therapeutic successes. The unmet medical need in NASH is no longer disputed, and progress in the understanding of its pathogenesis has resulted in the identification of many pharmacological targets. Key surrogate outcomes for therapeutic trials are now accepted by regulatory agencies, thus creating a path for drug registration. A set of non-invasive measurements enabled early-stage trials to be conducted expeditiously, thus providing early indications on the biological and possibly clinical actions of therapeutic candidates. This generated efficacy results for a number of highly promising compounds that are now in late-stage development. Intense research aimed at further improving the assessment of histological endpoints and in developing non-invasive predictive biomarkers is underway. This will help improve the design and feasibility of successful trials, ultimately providing patients with therapeutic options that can change the course of the disease.

Clinical utility of 30% relative decline in MRI-PDFF in predicting fibrosis regression in non-alcoholic fatty liver disease

OBJECTIVE

Emerging data suggest that a 30% relative decline in liver fat, as assessed by MRI-proton density fat fraction (MRI-PDFF), may be associated with Non-Alcoholic Fatty Liver Disease Activity Score improvement, but the association between decline in MRI-PDFF and fibrosis regression is not known. Therefore, we aimed to examine the association between ≥30% relative decline in MRI-PDFF and fibrosis regression in non-alcoholic fatty liver disease (NAFLD).

DESIGN

This prospective study included 100 well-characterised patients with biopsy-proven NAFLD with paired contemporaneous MRI-PDFF assessment at two time points. MRI-PDFF response was defined as ≥30% relative decline in MRI-PDFF. The primary outcome was ≥1 stage histological fibrosis regression.

RESULTS

The median (IQR) age was 54 (43-62) years and body mass index was 31.9 (29-36) kg/m2. In multivariable-adjusted logistic regression analysis (adjusted for age, gender, diabetes status, race/ethnicity, interval between biopsies, gamma-glutamyl transferase, liver stiffness by magnetic resonance elastography and change in platelet counts), MRI-PDFF response was an independent predictor of fibrosis regression with an adjusted OR of 6.46 (95% CI 1.1 to 37.0, p=0.04). The proportion of patients with MRI-PDFF response with fibrosis regression, no change in fibrosis and fibrosis progression was 40.0%, 24.6% and 13.0%, respectively, and the proportion of patients with MRI-PDFF response increased with fibrosis regression (p=0.03).

CONCLUSION

≥30% reduction in MRI-PDFF in early phase trials can provide a useful estimate of odds of ≥1 stage improvement in fibrosis. These data may be helpful in sample size estimation in non-alcoholic steatohepatitis trials.

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.

Non-alcoholic Fatty Liver Disease and Steatohepatitis: Risk Factors and Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) and its progressive subtype non-alcoholic steatohepatitis (NASH) are the most prevalent liver diseases, often leading to hepatocellular carcinoma (HCC). This review aims to describe the present knowledge of the risk factors responsible for the development of NAFLD and NASH. I performed a literature review identifying studies focusing on the complex pathogenic pathway and risk factors of NAFLD and steatohepatitis. The relationship between NAFLD and metabolic syndrome is well established and widely recognized. Obesity, dyslipidemia, type 2 diabetes, hypertension, and insulin resistance are the most common risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly suggests obesity and type 2 diabetes as risk factors of NASH and HCC. However, other elements, namely gender divergences, ethnicity, genetic factors, participation of innate immune system, oxidative stress, apoptotic pathways, and adipocytokines, take a leading role in the onset and promotion of NAFLD. Pathophysiological mechanisms that are responsible for NAFLD development and subsequent progression to NASH are insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell (HSC) activation, cytokine/adipokine signaling pathways, and genetic and environmental factors. Major pathophysiological findings of NAFLD are dysfunction of adipose tissue through the enhanced flow of free fatty acids (FFAs) and release of adipokines, and altered gut microbiome that generate proinflammatory signals and cause NASH progression. Understanding the pathophysiology and risk factors of NAFLD and NASH; this review could provide insight into the development of therapeutic strategies and useful diagnostic tools.

Lipid alterations in chronic liver disease and liver cancer

Lipids are a complex and diverse group of molecules with crucial roles in many physiological processes, as well as in the onset, progression, and maintenance of cancers. Fatty acids and cholesterol are the building blocks of lipids, orchestrating these crucial metabolic processes. In the liver, lipid alterations are prevalent as a cause and consequence of chronic hepatitis B and C virus infections, alcoholic hepatitis, and non-alcoholic fatty liver disease and steatohepatitis. Recent developments in lipidomics have also revealed that dynamic changes in triacylglycerols, phospholipids, sphingolipids, ceramides, fatty acids, and cholesterol are involved in the development and progression of primary liver cancer. Accordingly, the transcriptional landscape of lipid metabolism suggests a carcinogenic role of increasing fatty acids and sterol synthesis. However, limited mechanistic insights into the complex nature of the hepatic lipidome have so far hindered the development of effective therapies.

Nuclear Receptors Linking Metabolism, Inflammation, and Fibrosis in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) and its progressive form nonalcoholic steatohepatitis (NASH) comprise a spectrum of chronic liver diseases in the global population that can lead to end-stage liver disease and hepatocellular carcinoma (HCC). NAFLD is closely linked to the metabolic syndrome, and comorbidities such as type 2 diabetes, obesity and insulin resistance aggravate liver disease, while NAFLD promotes cardiovascular risk in affected patients. The pathomechanisms of NAFLD are multifaceted, combining hepatic factors including lipotoxicity, mechanisms of cell death and liver inflammation with extrahepatic factors including metabolic disturbance and dysbiosis. Nuclear receptors (NRs) are a family of ligand-controlled transcription factors that regulate glucose, fat and cholesterol homeostasis and modulate innate immune cell functions, including liver macrophages. In parallel with metabolic derangement in NAFLD, altered NR signaling is frequently observed and might be involved in the pathogenesis. Therapeutically, clinical data indicate that single drug targets thus far have been insufficient for reaching patient-relevant endpoints. Therefore, combinatorial treatment strategies with multiple drug targets or drugs with multiple mechanisms of actions could possibly bring advantages, by providing a more holistic therapeutic approach. In this context, peroxisome proliferator-activated receptors (PPARs) and other NRs are of great interest as they are involved in wide-ranging and multi-organ activities associated with NASH progression or regression. In this review, we summarize recent advances in understanding the pathogenesis of NAFLD, focusing on mechanisms of cell death, immunometabolism and the role of NRs. We outline novel therapeutic strategies and discuss remaining challenges.

Current considerations for clinical management and care of non-alcoholic fatty liver disease: Insights from the 1st International Workshop of the Canadian NASH Network (CanNASH)

Non-alcoholic fatty liver disease (NAFLD) affects approximately 8 million Canadians. NAFLD refers to a disease spectrum ranging from bland steatosis to non-alcoholic steatohepatitis (NASH). Nearly 25% of patients with NAFLD develop NASH, which can progress to liver cirrhosis and related end-stage complications. Type 2 diabetes and obesity represent the main risk factors for the disease. The Canadian NASH Network is a national collaborative organization of health care professionals and researchers with a primary interest in enhancing understanding, care, education, and research around NAFLD, with a vision of best practices for this disease state. At the 1st International Workshop of the CanNASH network in April 2021, a joint event with the single topic conference of the Canadian Association for the Study of the Liver (CASL), clinicians, epidemiologists, basic scientists, and community members came together to share their work under the theme of NASH. This symposium also marked the initiation of collaborations between Canadian and other key opinion leaders in the field representative of international liver associations. The main objective is to develop a policy framework that outlines specific targets, suggested activities, and evidence-based best practices to guide provincial, territorial, and federal organizations in developing multidisciplinary models of care and strategies to address this epidemic.

Expert Panel Review on Nonalcoholic Fatty Liver Disease in Persons With Human Immunodeficiency Virus

Nonalcoholic fatty liver disease (NAFLD) affects 25% of adults in the general population and is a disease spectrum ranging from steatosis to nonalcoholic steatohepatitis (NASH) to end-stage liver disease. NAFLD is an independent risk factor for cardiovascular disease, diabetes mellitus, and all-cause mortality, and NASH cirrhosis is a frequent indication for liver transplantation. In persons with human immunodeficiency virus (PWH), chronic liver disease is the second leading cause of non-human immunodeficiency virus-related mortality. Between 20% and 63% of PWH have NASH, and 14% to 63% have NASH with fibrosis. However, little is known about the optimal diagnostic strategies, risk factors for, and treatment of NAFLD in PWH. Here, we review current data on and identify knowledge gaps in the epidemiology, pathophysiology, diagnosis, and management of NAFLD in PWH and highlight priorities for research.

State-of-the-Art Overview of the Pharmacological Treatment of Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, and non-alcoholic steatohepatitis (NASH), a subtype of NAFLD, can progress to cirrhosis, hepatocellular carcinoma, and death. Nevertheless, the current treatment for NAFLD/NASH is limited to lifestyle modifications, and no drugs are currently officially approved as treatments for NASH. Many global pharmaceutical companies are pursuing the development of medications for the treatment of NASH, and results from phase 2 and 3 clinical trials have been published in recent years. Here, we review data from these recent clinical trials and reports on the efficacy of newly developed antidiabetic drugs in NASH treatment.

Inflammatory and fibrotic mechanisms in NAFLD-Implications for new treatment strategies

Non-alcoholic fatty liver disease is comprised of either simple steatosis (non-alcoholic fatty liver) or a more advanced inflammatory and fibrogenic stage (non-alcoholic steatohepatitis [NASH]). NASH affects a growing proportion of the global adult and pediatric population, leading to rising rates of liver fibrosis and hepatocellular carcinoma. NASH is a multifactorial disease that is part of a systemic metabolic disorder. Here, we provide an overview of the metabolic underpinnings of NASH pathogenesis and established drivers of inflammation and fibrosis. Clarification of underlying fibrogenic and inflammatory mechanisms will advance the development of novel treatment strategies as there are no approved therapies at present. We discuss emerging experimental approaches and potential novel investigational strategies derived from animal models including the inflammasome, epigenetic reprogramming, Hippo signaling, Notch signaling, engineered T cells to remove fibrogenic HSCs, and HSC-specific targeting therapies. Recently completed and ongoing clinical trials and antifibrotics are discussed, illuminating the growing expectation that one or more therapies will yield clinical benefit in NASH in the coming years.

Insights into the molecular targets and emerging pharmacotherapeutic interventions for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide. With no Food and Drug Administration approved drugs, current treatment options include dietary restrictions and lifestyle modification. NAFLD is closely associated with metabolic disorders such as obesity, type 2 diabetes, and dyslipidemia. Hence, clinically various pharmacological approaches using existing drugs such as antidiabetic, anti-obesity, antioxidants, and cytoprotective agents have been considered in the management of NAFLD and nonalcoholic steatohepatitis (NASH). However, several pharmacological therapies aiming to alleviate NAFLD-NASH are currently being examined at various phases of clinical trials. Emerging data from these studies with drugs targeting diverse molecular mechanisms show promising outcomes. This review summarizes the current understanding of the pathogenic mechanisms of NAFLD and provides an insight into the pharmacological targets and emerging therapeutics with specific interventional mechanisms. In addition, we also discuss the importance and utility of new approach methodologies and regulatory perspectives for NAFLD-NASH drug development.

Narrative review of current and emerging pharmacological therapies for nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is the most common cause of chronic liver disease today, and it has now emerged as the leading etiology of end-stage liver disease requiring liver transplantation. It is a progressive form of non-alcoholic fatty liver disease which can not only progress to cirrhosis of liver and hepatocellular carcinoma (HCC), but is associated with increased cardiovascular risks too. Despite all the advances in the understanding of the risk factors and the pathogenetic pathways involved in the pathogenesis and progression of NASH, an effective therapy for NASH has not been developed yet. Although lifestyle modifications including dietary modifications and physical activity remain the mainstay of therapy, there is an unmet need to develop a drug or a combination of drugs which can not only reduce the fatty infiltration of the liver, but also arrest the development and progression of fibrosis and advancement to cirrhosis of liver and HCC. The pharmacologic therapies which are being developed target the various components believed to be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD)/NASH which includes insulin resistance, lipid metabolism oxidative stress, lipid peroxidation, inflammatory and cell death pathways, and fibrosis. In this review, we summarize the current state of knowledge on pharmacotherapy of NASH, and also highlight the recent developments in the field, for optimizing the management and treatment of NASH.

Liver Fibrosis and MAFLD: From Molecular Aspects to Novel Pharmacological Strategies

Metabolic-associated fatty liver disease (MAFLD) is a new disease definition, and this nomenclature MAFLD was proposed to renovate its former name, non-alcoholic fatty liver disease (NAFLD). MAFLD/NAFLD have shared and predominate causes from nutrition overload to persistent liver damage and eventually lead to the development of liver fibrosis and cirrhosis. Unfortunately, there is an absence of effective treatments to reverse MAFLD/NAFLD-associated fibrosis. Due to the significant burden of MAFLD/NAFLD and its complications, there are active investigations on the development of novel targets and pharmacotherapeutics for treating this disease. In this review, we cover recent discoveries in new targets and molecules for antifibrotic treatment, which target pathways intertwined with the fibrogenesis process, including lipid metabolism, inflammation, cell apoptosis, oxidative stress, and extracellular matrix formation. Although marked advances have been made in the development of antifibrotic therapeutics, none of the treatments have achieved the endpoints evaluated by liver biopsy or without significant side effects in a large-scale trial. In addition to the discovery of new druggable targets and pharmacotherapeutics, personalized medication, and combinatorial therapies targeting multiple profibrotic pathways could be promising in achieving successful antifibrotic interventions in patients with MAFLD/NAFLD.