Combination therapy for non-alcoholic steatohepatitis: rationale, opportunities and challenges

Characterization and Pharmacological Validation of a Preclinical Model of NASH in Göttingen Minipigs

Background

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, which is associated with features of metabolic syndrome. NAFLD may progress in a subset of patients into nonalcoholic steatohepatitis (NASH) with liver injury resulting ultimately in cirrhosis and potentially hepatocellular carcinoma. Today, there is no approved treatment for NASH due to, at least in part, the lack of preclinical models recapitulating features of human disease. Here, we report the development of a dietary model of NASH in the Göttingen minipig.

Methods

First, we performed a longitudinal characterization of diet-induced NASH and fibrosis using biochemical, histological, and transcriptional analyses. We then evaluated the pharmacological response to Obeticholic acid (OCA) treatment for 8 weeks at 2.5mg/kg/d, a dose matching its active clinical exposure.

Results

Serial histological examinations revealed a rapid installation of NASH driven by massive steatosis and inflammation, including evidence of ballooning. Furthermore, we found the progressive development of both perisinusoidal and portal fibrosis reaching fibrotic septa after 6 months of diet. Histological changes were mechanistically supported by well-defined gene signatures identified by RNA Seq analysis. While treatment with OCA was well tolerated throughout the study, it did not improve liver dysfunction nor NASH progression. By contrast, OCA treatment resulted in a significant reduction in diet-induced fibrosis in this model.

Conclusions

These results, taken together, indicate that the diet-induced NASH in the Göttingen minipig recapitulates most of the features of human NASH and may be a model with improved translational value to prioritize drug candidates toward clinical development.

Novel therapeutic targets for cholestatic and fatty liver disease

Cholestatic and non-alcoholic fatty liver disease (NAFLD) share several key pathophysiological mechanisms which can be targeted by novel therapeutic concepts that are currently developed for both areas. Nuclear receptors (NRs) are ligand-activated transcriptional regulators of key metabolic processes including hepatic lipid and glucose metabolism, energy expenditure and bile acid (BA) homoeostasis, as well as inflammation, fibrosis and cellular proliferation. Dysregulation of these processes contributes to the pathogenesis and progression of cholestatic as well as fatty liver disease, placing NRs at the forefront of novel therapeutic approaches. This includes BA and fatty acid activated NRs such as farnesoid-X receptor (FXR) and peroxisome proliferator-activated receptors, respectively, for which high affinity therapeutic ligands targeting specific or multiple isoforms have been developed. Moreover, novel liver-specific ligands for thyroid hormone receptor beta 1 complete the spectrum of currently available NR-targeted drugs. Apart from FXR ligands, BA signalling can be targeted by mimetics of FXR-activated fibroblast growth factor 19, modulation of their enterohepatic circulation through uptake inhibitors in hepatocytes and enterocytes, as well as novel BA derivatives undergoing cholehepatic shunting (instead of enterohepatic circulation). Other therapeutic approaches more directly target inflammation and/or fibrosis as critical events of disease progression. Combination strategies synergistically targeting metabolic disturbances, inflammation and fibrosis may be ultimately necessary for successful treatment of these complex and multifactorial disorders.

Follistatin Alleviates Hepatic Steatosis in NAFLD via the mTOR Dependent Pathway

PURPOSE

In this study, we aimed to investigate the effect of follistatin (FST) on hepatic steatosis in NAFLD and the underlying mechanism, which has rarely been reported before.

METHODS

Liver samples from NAFLD patients and normal liver samples (from liver donors) were collected to investigate hepatic FST expression in humans. Additionally, human liver cells (LO2) were treated with free fatty acid (FFA) to induce lipid accumulation. Furthermore, lentivirus with FST overexpression or knockdown vectors were used to generate stable cell lines, which were subsequently treated with FFA or FFA and rapamycin. In the animal experiments, male C57BL/6J mice were fed with a high-fat diet (HFD) to induce NAFLD, after which the adeno-associated virus (AAV) gene vectors for FST overexpression were administered. In both cell culture and mice, we evaluated morphological changes and the protein expression of sterol regulatory element-binding protein1 (SREBP1), acetyl-CoA carboxylase1 (ACC1), carbohydrate-responsive element-binding protein (ChREBP), fatty acid synthase (FASN), and Akt/mTOR signaling. The body weight and serum parameters of the mice were also measured.

RESULTS

Hepatic FST expression level was higher in NAFLD patients compared to normal samples. In LO2 cells, FST overexpression alleviated lipid accumulation and lipogenesis, whereas FST knockdown aggravated hepatic steatosis. FST could regulate Akt/mTOR signaling, and the mTOR inhibitor rapamycin abolished the effect of FST knockdown on hepatic de novo lipogenesis (DNL). Furthermore, FST expression was increased in HFD mice compared to the corresponding controls. FST overexpression in mice reduced body weight gain, hyperlipidemia, hepatic DNL, and suppressed Akt/mTOR signaling.

CONCLUSION

Hepatic FST expression increases in NAFLD and plays a protective role in hepatic steatosis. FST overexpression gene therapy alleviates hepatic steatosis via the mTOR pathway.Therefore, gene therapy for FST is a promising treatment in NAFLD.

Hepatic MIR20B promotes nonalcoholic fatty liver disease by suppressing PPARA

Background

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and imbalances in lipid metabolism in the liver. Although nuclear receptors (NRs) play a crucial role in hepatic lipid metabolism, the underlying mechanisms of NR regulation in NAFLD remain largely unclear.

Methods

Using network analysis and RNA-seq to determine the correlation between NRs and microRNA in human NAFLD patients, we revealed that MIR20B specifically targets PPARA. MIR20B mimic and anti-MIR20B were administered to human HepG2 and Huh-7 cells and mouse primary hepatocytes as well as high fat diet (HFD)- or methionine-deficient diet (MCD)-fed mice to verify the specific function of MIR20B in NAFLD. We tested the inhibition of the therapeutic effect of a PPARα agonist, fenofibrate, by Mir20b and the synergic effect of combination of fenofibrate with anti-Mir20b in NAFLD mouse model.

Results

We revealed that MIR20B specifically targets PPARA through miRNA regulatory network analysis of nuclear receptor genes in NAFLD. The expression of MIR20B was upregulated in free fatty acid (FA)-treated hepatocytes and the livers of both obesity-induced mice and NAFLD patients. Overexpression of MIR20B significantly increased hepatic lipid accumulation and triglyceride levels. Furthermore, MIR20B significantly reduced FA oxidation and mitochondrial biogenesis by targeting PPARA. In Mir20b-introduced mice, the effect of fenofibrate to ameliorate hepatic steatosis was significantly suppressed. Finally, inhibition of Mir20b significantly increased FA oxidation and uptake, resulting in improved insulin sensitivity and a decrease in NAFLD progression. Moreover, combination of fenofibrate and anti-Mir20b exhibited the synergic effect on improvement of NAFLD in MCD-fed mice.

Conclusions

Taken together, our results demonstrate that the novel MIR20B targets PPARA, plays a significant role in hepatic lipid metabolism, and present an opportunity for the development of novel therapeutics for NAFLD.

Funding

This research was funded by Korea Mouse Phenotyping Project (2016M3A9D5A01952411), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2020R1F1A1061267, 2018R1A5A1024340, NRF-2021R1I1A2041463, 2020R1I1A1A01074940), and the Future-leading Project Research Fund (1.210034.01) of UNIST.

A small molecule targeting ALOX12-ACC1 ameliorates nonalcoholic steatohepatitis in mice and macaques

[Figure: see text].

Caffeine and EGCG Alleviate High-Trans Fatty Acid and High-Carbohydrate Diet-Induced NASH in Mice: Commonality and Specificity

Caffeine and epigallocatechin-3-gallate (EGCG), which respectively, are the main functional extracts from coffee and green tea, and present protective effects against non-alcoholic fatty liver diseases (NAFLD). These two beverages and their functional extracts are highly recommended as potential treatments for obesity and NAFLD in clinics; however, their pharmacodynamic effects and pharmacological mechanisms in non-alcoholic steatohepatitis (NASH) remain unclear. Therefore, the aim of this study was to explore the commonality and specificity of the pharmacodynamic effects and pharmacological mechanisms of caffeine and EGCG on NASH mice, which were fed with a high-trans fatty acid/high-carbohydrate (HFHC) diet. C57BL/6J mice were fed a normal diet (control group) or an HFHC diet (HFHC group) for 24 weeks. HFHC group mice were additionally treated with caffeine (75 mg/kg) or EGCG (100 mg/kg) for 6 weeks, using obeticholic acid (OCA,10 mg/kg) as a positive control group. The pharmacological effects of the drugs, including effects on glucose and lipid metabolism and liver inflammation and fibrosis, were evaluated. Gene expression in liver tissue samples from the different groups were assessed. Both caffeine and EGCG significantly reduced the liver manifestations of NASH induced by HFHC. The pathological aspects of liver lipid deposition, inflammation, and liver fibrosis in both groups were strongly ameliorated. Of note, most indexes were strongly reversed in the caffeine group, although AST activity, fasting blood glucose, and the HOMA-IR index were improved in the ECGC group. There were 714 differentially expressed genes between the caffeine and HFHC groups and 268 differentially expressed genes between the EGCG and HFHC groups. Twenty and 17 NASH-related KEGG signaling pathways were enriched by caffeine and EGCG. This study confirmed that 75 mg/kg caffeine and 100 mg/kg EGCG could significantly improve liver lipid deposition, glucose metabolism, inflammation, and fibrosis in a mouse model of NASH induced by HFHC. The bioinformatics platform we built for caffeine and EGCG in NASH disease found that the two drugs may greatly overlap in improving the mechanism related to NASH inflammation. However, caffeine may have better potential in regulating glucose metabolism and EGCG may have better potential in regulating lipid metabolism.

The New Therapeutic Approaches in the Treatment of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease which is characterized by extremely complex pathogenetic mechanisms and multifactorial etiology. Some of the many pathophysiological mechanisms involved in the development of NAFLD include oxidative stress, impaired mitochondrial metabolism, inflammation, gut microbiota, and interaction between the brain-liver-axis and the regulation of hepatic lipid metabolism. The new therapeutic approaches in the treatment of NAFLD are targeting some of these milestones along the pathophysiological pathway and include drugs like agonists of peroxisome proliferator-activated receptors (PPARs), glucagon-like peptide-1 (GLP-1) agonists, sodium/glucose transport protein 2 (SGLT2) inhibitors, farnesoid X receptor (FXR) agonists, probiotics, and symbiotics. Further efforts in biomedical sciences should focus on the investigation of the relationship between the microbiome, liver metabolism, and response to inflammation, systemic consequences of metabolic syndrome.

Obesity and Nonalcoholic Fatty Liver Disease

Obesity and nonalcoholic fatty liver disease (NAFLD) have a significant global impact, and their complications are quickly becoming a reason for primary care visits and hospitalizations. This article provides an overview of NAFLD and obesity, pathogenesis of NAFLD and nonalcoholic steatohepatitis, clinical presentation and diagnostic criteria, and a review of practice guidelines. The current mainstay of treatment for NAFLD are lifestyle modifications and include a plan to eat, move, and change behavior. The future holds potential for new drug therapies in treating NAFLD. More research is needed to move these treatments forward.

What Does the Future Hold for Patients With Nonalcoholic Steatohepatitis: Diagnostic Strategies and Treatment Options in 2021 and Beyond?

Nonalcoholic steatohepatitis (NASH) can progress to cirrhosis and its complications, including hepatocellular carcinoma. Given that the majority of patients with NASH are asymptomatic, developing screening strategies to identify those individuals at risk for progressive NASH remains a highly unmet need. Furthermore, noninvasive tests that accurately predict disease progression as part of the natural history of NASH or regression in response to treatment are urgently needed to decrease the reliance on repeat liver biopsies. To date, there are no US Food and Drug Administration (FDA)-approved medications for NASH that can resolve steatohepatitis and lead to fibrosis regression. The lack of FDA-approved therapy has led to apathy in diagnosis and referral for specialty care. However, several therapeutic agents are rapidly progressing through the different phases of clinical trials with several already in phase 3 programs. In this review, we provide a summary of recent developments in NASH diagnostics and therapeutics that are likely to shape the future management of this underdiagnosed and undertreated disease.

Systematic review with network meta-analysis: comparative efficacy of pharmacologic therapies for fibrosis improvement and resolution of NASH

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is a common cause of chronic liver disease. There is a major need to understand the efficacy of different pharmacological agents for the treatment of NASH.

AIM

To assess the relative rank-order of different pharmacological interventions in fibrosis improvement and NASH resolution.

METHODS

A comprehensive search of several databases was conducted by an experienced librarian. We included randomised controlled-trials (RCTs) comparing pharmacological interventions in patients with biopsy-proven NASH. The primary outcome was ≥1 stage improvement in fibrosis. The secondary outcome was NASH resolution.

RESULTS

A total of 26 RCTs with 23 interventions met the eligibility criteria. Lanifibranor and obeticholic acid had the highest probability of being ranked the most effective intervention for achieving ≥1 stage of fibrosis improvement (SUCRA 0.78) and (SUCRA 0.77), respectively. For NASH resolution, semaglutide, liraglutide and vitamin E plus pioglitazone had the highest probability of being ranked the most effective intervention for achieving NASH resolution (SUCRA 0.89), (SUCRA 0.84) and (SUCRA 0.83), respectively. Lanifibranor, obeticholic acid, pioglitazone and vitamin E were significantly better than placebo in achieving ≥1 stage of fibrosis improvement. Conversely, semaglutide, liraglutide, vitamine E plus pioglitazone, pioglitazone, lanifibranor and obeticholic acid were significantly better than placebo in achieving NASH resolution.

CONCLUSION

These data provide relative rank-order efficacy of various NASH therapies in terms of their improvements in liver fibrosis and NASH resolution. Therapies that have been shown to improve NASH resolution may be combined with therapies that have an antifibrotic effect to further boost treatment response rate in future.

Non-Alcoholic Steatohepatitis (NASH) - A Review of a Crowded Clinical Landscape, Driven by a Complex Disease

Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD), characterized by chronic inflammation and accumulation of fat in liver tissue. Affecting estimated 35 million people globally, NASH is the most common chronic liver condition in Western populations, and with patient numbers growing rapidly, the market for NASH therapy is projected to rise to $27.2 B in 2029. Despite this clinical need and attractive commercial opportunity, there are no Food and Drug Administration (FDA)-approved therapies specifically for this disease. Many have tried and unfortunately failed to find a drug, or drug combination, capable of unravelling the complexities of this metabolic condition. At the time of writing this review, only Zydus Cadila’s new drug application for Saroglitazar had been approved (2020) for NASH therapy in India. However, it is hoped that this dearth of therapy options will improve as several drug candidates progress through late-stage clinical development. Obeticholic acid (Intercept Pharmaceuticals), Cenicriviroc (Allergan), Aramchol (Galmed Pharmaceuticals), Resmetirom (Madrigal Pharmaceuticals), Dapagliflozin and Semaglutide (Novo Nordisk) are in advanced Phase 3 clinical trials, while Belapectin (Galectin Therapeutics), MSDC-0602K (Cirius Therapeutics), Lanifibranor (Inventiva), Efruxifermin (Akero) and Tesamorelin (Theratechnologies) are expected to start Phase 3 trials soon. Here, we have performed an exhaustive review of the current therapeutic landscape for this disease and compared, in some detail, the fortunes of different drug classes (biologics vs small molecules) and target molecules. Given the complex pathophysiology of NASH, the use of drug combination, different mechanisms of actions and the targeting of each stage of the disease will likely be required. Hence, the development of a single therapy for NASH seems challenging and unlikely, despite the plethora of later stage trials due to report. We therefore predict that clinical, patient and company interest in pipeline and next-generation therapies will remain high for some time to come.

The Role of Innate Immune Cells in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a very common hepatic pathology featuring steatosis and is linked to obesity and related conditions, such as the metabolic syndrome. When hepatic steatosis is accompanied by inflammation, the disorder is defined as nonalcoholic steatohepatitis (NASH), which in turn can progress toward fibrosis development that can ultimately result in cirrhosis. Cells of innate immunity, such as neutrophils or macrophages, are central regulators of NASH-related inflammation. Recent studies utilizing new experimental technologies, such as single-cell RNA sequencing, have revealed substantial heterogeneity within the macrophage populations of the liver, suggesting distinct functions of liver-resident Kupffer cells and recruited monocyte-derived macrophages with regards to regulation of liver inflammation and progression of NASH pathogenesis. Herein, we discuss recent developments concerning the function of innate immune cell subsets in NAFLD and NASH.

Elafibranor and liraglutide improve differentially liver health and metabolism in a mouse model of non-alcoholic steatohepatitis

BACKGROUND & AIMS

This study aimed to assess and compare the effects of the GLP-1 analog liraglutide and the PPARα/δ agonist elafibranor on liver histology and their impact on hepatic lipidome, metabolome, Kupffer and hepatic stellate cell activation in a model of advanced non-alcoholic fatty liver disease (NAFLD).

METHODS

Male C57BL/6JRj mice with biopsy-confirmed hepatosteatosis and fibrosis induced by 36-week Amylin liver NASH (AMLN) diet (high-fat, fructose and cholesterol) were randomized to receive for 12 weeks: (a) liraglutide (0.4 mg/kg/day s.c.), (b) elafibranor (30 mg/kg/day p.o.) and (c) vehicle. Metabolic status, liver pathology, markers of inflammation, Kupffer and stellate cell activation, and metabolomics/lipidomics were assessed at study completion.

RESULTS

Elafibranor and liraglutide improved weight, insulin sensitivity, glucose homeostasis and NAFLD activity score (pre-to-post biopsy). Elafibranor had a profound effect on hepatic lipidome, demonstrated by reductions in glycerides, increases in phospholipids, and by beneficial regulation of mediators of fatty acid oxidation, inflammation and oxidative stress. Liraglutide had a major impact on inflammatory and fibrogenic markers of Kupffer and hepatic stellate cell activation (Galectin-3, Collagen type I alpha 1, alpha-smooth muscle actin). Liraglutide exerted beneficial effects on bile acid and carbohydrate metabolism, demonstrated by restorations of the concentrations of bile acids, glycogen metabolism by-products and pentoses, thus facilitating glycogen utilization turnover and nucleic acid formation.

CONCLUSIONS

Liraglutide and elafibranor robustly but through different pathways improve overall metabolic health and liver status in NAFLD. These data indicate important differences in the respective mechanisms of action and support the notion for their evaluation as combination therapies in the future.

Nonalcoholic fatty liver disease (NAFLD) from pathogenesis to treatment concepts in humans

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) comprises hepatic alterations with increased lipid accumulation (steatosis) without or with inflammation (nonalcoholic steatohepatitis, NASH) and/or fibrosis in the absence of other causes of liver disease. NAFLD is developing as a burgeoning health challenge, mainly due to the worldwide obesity and diabetes epidemics.

SCOPE OF REVIEW

This review summarizes the knowledge on the pathogenesis underlying NAFLD by focusing on studies in humans and on hypercaloric nutrition, including effects of saturated fat and fructose, as well as adipose tissue dysfunction, leading to hepatic lipotoxicity, abnormal mitochondrial function, and oxidative stress, and highlights intestinal dysbiosis. These mechanisms are discussed in the context of current treatments targeting metabolic pathways and the results of related clinical trials.

MAJOR CONCLUSIONS

Recent studies have provided evidence that certain conditions, for example, the severe insulin-resistant diabetes (SIRD) subgroup (cluster) and the presence of an increasing number of gene variants, seem to predispose for excessive risk of NAFLD and its accelerated progression. Recent clinical trials have been frequently unsuccessful in halting or preventing NAFLD progression, perhaps partly due to including unselected cohorts in later stages of NAFLD. On the basis of this literature review, this study proposed screening in individuals with the highest genetic or acquired risk of disease progression, for example, the SIRD subgroup, and developing treatment concepts targeting the earliest pathophysiolgical alterations, namely, adipocyte dysfunction and insulin resistance.

Retinoic acid-related orphan receptor gamma t (RORγt) inverse agonists/antagonists for the treatment of inflammatory diseases - where are we presently?

Introduction: The transcription factor retinoic acid-related orphan receptor gamma t (RORγt) has been identified as the master regulator of T_H17 cell differentiation and IL-17/22 production and is therefore an attractive target for the treatment of inflammatory diseases. Several orally or topically administered small molecule RORγt inverse agonists (RIAs) have progressed up to the end of clinical Phase 2.Areas covered: Based on publications and patent evaluations this review summarizes the evolution of the chemical matter for all 16 pharmaceutical companies, who develop(ed) a clinical-stage RIAs (until March 2021). Structure proposals for some clinical stage RIAs are presented and the outcome of the clinical trials is discussed.Expert opinion: So far, the clinical trials have been plagued with a high attrition rate. Main reasons were lack of efficacy (topical) or safety signals (oral) as well as, amongst other things, thymic lymphomas as seen with BMS-986251 in a preclinical study and liver enzyme elevations in humans with VTP-43742. Possibilities to mitigate these risks could be the use of RIAs with different chemical structures not interfering with thymocytes maturation and no livertox-inducing properties. With new frontrunners (e.g., ABBV-157 (cedirogant), BI 730357 or IMU-935) this is still an exciting time for this treatment approach.

Targeting cell-intrinsic metabolism for antifibrotic therapy

In recent years, there have been major advances in our understanding of the mechanisms underlying fibrosis progression and regression, and how coordinated interactions between parenchymal and non-parenchymal cells impact on the fibrogenic process. Recent studies have highlighted that metabolic reprogramming of parenchymal cells, immune cells (immunometabolism) and hepatic stellate cells is required to support the energetic and anabolic demands of phenotypic changes and effector functions. In this review, we summarise how targeting cell-intrinsic metabolic modifications of the main fibrogenic cell actors may impact on fibrosis progression and we discuss the antifibrogenic potential of metabolically targeted interventions.

Silybin alleviates hepatic lipid accumulation in methionine-choline deficient diet-induced nonalcoholic fatty liver disease in mice via peroxisome proliferator-activated receptor α

Nonalcoholic fatty liver disease (NAFLD) is regarded as the most common liver disease with no approved therapeutic drug currently. Silymarin, an extract from the seeds of Silybum marianum, has been used for centuries for the treatment of various liver diseases. Although the hepatoprotective effect of silybin against NAFLD is widely accepted, the underlying mechanism and therapeutic target remain unclear. In this study, NAFLD mice caused by methionine-choline deficient (MCD) diet were orally administrated with silybin to explore the possible mechanism and target. To clarify the contribution of peroxisome proliferator-activated receptor α (PPARα), PPARα antagonist GW6471 was co-administrated with silybin to NAFLD mice. Since silybin was proven as a PPARα partial agonist, the combined effect of silybin with PPARα agonist, fenofibrate, was then evaluated in NAFLD mice. Serum and liver samples were collected to analyze the pharmacological efficacy and expression of PPARα and its targets. As expected, silybin significantly protected mice from MCD-induced NAFLD. Furthermore, silybin reduced lipid accumulation via activating PPARα, inducing the expression of liver cytosolic fatty acid-binding protein, carnitine palmitoyltransferase (Cpt)-1a, Cpt-2, medium chain acyl-CoA dehydrogenase and stearoyl-CoA desaturase-1, and suppressing fatty acid synthase and acetyl-CoA carboxylase α. GW6471 abolished the effect of silybin on PPARα signal and hepatoprotective effect against NAFLD. Moreover, as a partial agonist for PPARα, silybin impaired the powerful lipid-lowering effect of fenofibrate when used together. Taken together, silybin protected mice against NAFLD via activating PPARα to diminish lipid accumulation and it is not suggested to simultaneously take silybin and classical PPARα agonists for NAFLD therapy.

Nonalcoholic Fatty Liver Disease (NAFLD). Mitochondria as Players and Targets of Therapies?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and represents the hepatic expression of several metabolic abnormalities of high epidemiologic relevance. Fat accumulation in the hepatocytes results in cellular fragility and risk of progression toward necroinflammation, i.e., nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Several pathways contribute to fat accumulation and damage in the liver and can also involve the mitochondria, whose functional integrity is essential to maintain liver bioenergetics. In NAFLD/NASH, both structural and functional mitochondrial abnormalities occur and can involve mitochondrial electron transport chain, decreased mitochondrial β-oxidation of free fatty acids, excessive generation of reactive oxygen species, and lipid peroxidation. NASH is a major target of therapy, but there is no established single or combined treatment so far. Notably, translational and clinical studies point to mitochondria as future therapeutic targets in NAFLD since the prevention of mitochondrial damage could improve liver bioenergetics.

Emerging synthetic drugs for the treatment of liver cirrhosis

Introduction: The number of deaths and prevalent cases of cirrhosis are increasing worldwide, but there are no licensed antifibrotic or pro-regenerative medicines and liver transplantation is a limited resource. Cirrhosis is characterized by extreme liver fibrosis, organ dysfunction, and complications related to portal hypertension. Advances in our understanding of liver fibrosis progression and regression following successful etiological therapy betray vulnerabilities in common and disease-specific mechanisms that could be targeted pharmacologically.Area covered: This review summarizes the cellular and molecular pathogenesis of cirrhosis as a preface to discussion of the current drug development landscape. The dominant indication for global pharma R&D pipelines is cirrhosis related to nonalcoholic steatohepatitis (NASH). We searched Clinicaltrials.gov, GlobalData, Pharmaprojects and PubMed for pertinent information on emerging synthetic drugs for cirrhosis, with a focus on compounds listed in phase 2 and phase 3 trials.Expert opinion: Although cirrhosis can regress following successful etiological treatment, there are no specific antifibrotic or pro-regenerative drugs approved for this condition. Obstacles to drug development in cirrhosis include intrinsic biological factors, a heterogeneous patient population, and lack of acceptable surrogate endpoints. Nevertheless, several synthetic drugs are being evaluated in clinical trials and the NASH field is rapidly embracing a drug combination approach.

A single-letter change in an acronym: signals, reasons, promises, challenges, and steps ahead for moving from NAFLD to MAFLD

Introduction: We are currently at the dawn of a revolution in the field of fatty liver diseases. Recently, a consensus recommended 'metabolic (dysfunction) associated fatty liver disease' (MAFLD) as a more appropriate name to describe fatty liver disease associated with metabolic dysfunction, ultimately suggesting that the old acronym nonalcoholic fatty liver disease (NAFLD) should be abandoned.Areas covered: In this viewpoint, we discuss the reasons and relevance of this semantic modification through five different conceptual domains, i.e., 1) signals, 2) reasons, 2) promises, 4) challenges and 5) steps ahead.Expert opinion: The road ahead will not be traveled without major challenges. Further research to evaluate the positive and negative impacts of the nomenclature change is warranted. However, this modification should encourage increased disease awareness among policymakers and stimulate public and private investments leading to more effective therapy development.

The Relationship Between Type 2 Diabetes, NAFLD, and Cardiovascular Risk

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are strongly associated. Both also associate with an increased risk of cardiovascular disease (CVD).

RECENT FINDINGS

Several studies have provided evidence that NAFLD could be an independent CVD risk factor. Given the strong association between NAFLD and T2DM, assessing the independent CV effect of these two conditions remains challenging. However, patients with T2DM and NAFLD exhibit higher risk of CVD compared with T2DM without NAFLD suggesting a potential synergistic increase of CV risk in patients with both T2DM and NAFLD supported by several shared pathophysiological pathways. Several anti-diabetic therapies have shown beneficial effect on both NAFLD and CVD. Patients with T2DM and NAFLD should be considered at high risk of CVD and could benefit from more intensive CV prevention. Additional long-term follow-up is needed to demonstrate that the treatment of NAFLD effectively reduces the risk of CVD.

Individualized Polygenic Risk Score Identifies NASH in the Eastern Asia Region: A Derivation and Validation Study

INTRODUCTION

Strong evidence indicates that multiple genetic and environmental risk factors play a role in the pathogenesis of nonalcoholic steatohepatitis (NASH). We aimed to develop and validate a novel nomogram, incorporating both genetic and clinical factors, for predicting NASH.

METHODS

A total of 1,070 Asian individuals with biopsy-confirmed nonalcoholic fatty liver disease (NAFLD) from 2 countries (China and South Korea) were recruited. The histological spectrum of NAFLD was classified according to the NASH clinical research network scoring system. The nomogram was developed in the Chinese training set (n = 402), and then, it was validated in both the Chinese internal validation set (n = 136) and the external Korean validation cohort (n = 532), respectively.

RESULTS

Sex, metabolic syndrome, insulin resistance, serum aspartate aminotransferase levels, and PNPLA3 (rs738409) and HSD17B13 (rs72613567) genetic variants were strongly associated with NASH. Based on their regression coefficients, we developed a nomogram with good discriminatory ability (area under the receiver operating characteristic curve: 0.81, 95% confidence interval [CI] 0.77-0.85) and good calibration (Hosmer-Lemeshow test, P = 0.794) for identifying NASH. In the 2 validation cohorts, the nomogram showed high area under the receiver operating characteristic curves (internal validation set: 0.80, 95% CI 0.72-0.88; external validation cohort: 0.76, 95% CI 0.72-0.80) and good calibration.

DISCUSSION

Our newly developed and externally validated nomogram, incorporating both genetic and clinical risk factors, may be conveniently used to predict NASH. Further validation studies in other ethnic groups are warranted to confirm its diagnostic utility to identify NASH, among patients with biopsy-proven NAFLD.

Treatments for NAFLD: State of Art

Non-alcoholic fatty liver disease (NAFLD) is to date the most common chronic liver disease in clinical practice and, consequently, a major health problem worldwide. It affects approximately 30% of adults in the general population and up to 70% of patients with type 2 diabetes (T2DM). Despite the current knowledge of the epidemiology, pathogenesis, and natural history of NAFLD, no specific pharmacological therapies are until now approved for this disease and, consequently, general strategies have been proposed to manage it. They include: (a) lifestyle change in order to promote weight loss by diet and physical activity, (b) control of the main cardiometabolic risk factors, (c) correction of all modifiable risk factors leading the development and progression of advanced forms of NAFLD, and (d) prevention of hepatic and extra-hepatic complications. In the last decade, several potential agents have been widely investigated for the treatment of NAFLD and its advanced forms—shedding some light but casting a few shadows. They include some glucose-lowering drugs (such as pioglitazone, glucagon-like peptide-1 (GLP-1) receptor agonists, sodium-glucose co-transporter-2 (SGLT-2) inhibitors), antioxidants (such as vitamin E), statins or other lipid lowering agents, bile and non-bile acid farnesoid X activated receptor (FXR) agonists, and others. This narrative review discusses in detail the different available approaches with the potential to prevent and treat NAFLD and its advanced forms.

Influence of Genistein on Hepatic Lipid Metabolism in an In Vitro Model of Hepatic Steatosis

Nonalcoholic fatty liver disease (NAFLD) is among the leading causes of end-stage liver disease. The impaired hepatic lipid metabolism in NAFLD is exhibited by dysregulated PPARα and SREBP-1c signaling pathways, which are central transcription factors associated with lipid degradation and de novo lipogenesis. Despite the growing prevalence of this disease, current pharmacological treatment options are unsatisfactory. Genistein, a soy isoflavone, has beneficial effects on lipid metabolism and may be a candidate for NAFLD treatment. In an in vitro model of hepatic steatosis, primary human hepatocytes (PHHs) were incubated with free fatty acids (FFAs) and different doses of genistein. Lipid accumulation and the cytotoxic effects of FFAs and genistein treatment were evaluated by colorimetric and enzymatic assays. Changes in lipid homeostasis were examined by RT-qPCR and Western blot analyses. PPARα protein expression was induced in steatotic PHHs, accompanied by an increase in CPT1L and ACSL1 mRNA. Genistein treatment increased PPARα protein expression only in control PHHs, while CPTL1 and ACSL1 were unchanged and PPARα mRNA was reduced. In steatotic PHHs, genistein reversed the increase in activated SREBP-1c protein. The model realistically reflected the molecular changes in hepatic steatosis. Genistein suppressed the activation of SREBP-1c in steatotic hepatocytes, but the genistein-mediated effects on PPARα were abolished by high hepatic lipid levels.

An update on drug development for the treatment of nonalcoholic fatty liver disease - from ongoing clinical trials to future therapy

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) represents an increasingly recognized disease entity with rising prevalence of 25% in the general population. Given the epidemic increase, regulatory agencies have defined an unmet medical need and implemented initiatives to expedite the development of drugs for NASH treatment.

AREAS COVERED

Literature search in Medline and worldwide web was accessed latest in 23.01.2021. In recent years new drugs acting on various pathophysiological processes in NASH have entered clinical development. These drugs combine beneficial metabolic effects with anti-inflammatory and anti-fibrotic effects to treat NASH. Current drug classes being investigated for NASH treatment are agonists of nuclear receptors such as FXR agonists (including FGF19), PPAR agonists, chemokine receptor inhibitors, thyroid hormone receptor-ß agonists and analogues of enterohepatic hormones including GLP-1 and FGF21 or SGLT2 inhibitors.

EXPERT OPINION

Obeticholic acid is the only drug with significant benefit in the phase 3 interim results and remains the candidate for first conditional approval as a NASH therapeutic. However, monotherapy with these drugs leads to a histological resolution of NASH in less than one-third of patients in recent trials. Therefore, the future of NASH therapy will putatively be a combination therapy of two different drug classes with complementary effects.

Glucagon-Like Peptide-1 Receptor Agonists for Treatment of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: An Updated Meta-Analysis of Randomized Controlled Trials

To assess the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for treatment of nonalcoholic fatty liver disease (NAFLD) or steatohepatitis (NASH), we performed a systematic review and meta-analysis of randomized controlled trials (RCTs). Three large electronic databases were systematically searched (up to 15 December 2020) to identify placebo-controlled or active-controlled RCTs using different GLP-1 RAs. We included eleven placebo-controlled or active-controlled phase-2 RCTs (involving a total of 936 middle-aged individuals) that used liraglutide (n = 6 RCTs), exenatide (n = 3 RCTs), dulaglutide (n = 1 RCT) or semaglutide (n = 1 RCT) to specifically treat NAFLD or NASH, detected by liver biopsy (n = 2 RCTs) or imaging techniques (n = 9 RCTs). Compared to placebo or reference therapy, treatment with GLP-1 RAs for a median of 26 weeks was associated with significant reductions in the absolute percentage of liver fat content on magnetic resonance-based techniques (pooled weighted mean difference: −3.92%, 95% confidence intervals (CI) −6.27% to −1.56%) and serum liver enzyme levels, as well as with greater histological resolution of NASH without worsening of liver fibrosis (pooled random-effects odds ratio 4.06, 95% CI 2.52–6.55; for liraglutide and semaglutide only). In conclusion, treatment with GLP-1 RAs (mostly liraglutide and semaglutide) is a promising treatment option for NAFLD or NASH that warrants further investigation.

Glucagon-Like Peptide-1 Receptor Agonists for Treatment of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: An Updated Meta-Analysis of Randomized Controlled Trials

To assess the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for treatment of nonalcoholic fatty liver disease (NAFLD) or steatohepatitis (NASH), we performed a systematic review and meta-analysis of randomized controlled trials (RCTs). Three large electronic databases were systematically searched (up to 15 December 2020) to identify placebo-controlled or active-controlled RCTs using different GLP-1 RAs. We included eleven placebo-controlled or active-controlled phase-2 RCTs (involving a total of 936 middle-aged individuals) that used liraglutide (n = 6 RCTs), exenatide (n = 3 RCTs), dulaglutide (n = 1 RCT) or semaglutide (n = 1 RCT) to specifically treat NAFLD or NASH, detected by liver biopsy (n = 2 RCTs) or imaging techniques (n = 9 RCTs). Compared to placebo or reference therapy, treatment with GLP-1 RAs for a median of 26 weeks was associated with significant reductions in the absolute percentage of liver fat content on magnetic resonance-based techniques (pooled weighted mean difference: −3.92%, 95% confidence intervals (CI) −6.27% to −1.56%) and serum liver enzyme levels, as well as with greater histological resolution of NASH without worsening of liver fibrosis (pooled random-effects odds ratio 4.06, 95% CI 2.52–6.55; for liraglutide and semaglutide only). In conclusion, treatment with GLP-1 RAs (mostly liraglutide and semaglutide) is a promising treatment option for NAFLD or NASH that warrants further investigation.

Revealing the role of peroxisome proliferator-activated receptor β/δ in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), a form of chronic liver disease that occurs in individuals with no significant alcohol abuse, has become an increasing concern for global health. NAFLD is defined as the presence of lipid deposits in hepatocytes and it ranges from hepatic steatosis (fatty liver) to steatohepatitis. Emerging data from both preclinical studies and clinical trials suggest that the peroxisome proliferator-activated receptor (PPAR)β/δ plays an important role in the control of carbohydrate and lipid metabolism in liver, and its activation might hinder the progression of NAFLD. Here, we review the latest information on the effects of PPARβ/δ on NAFLD, including its capacity to reduce lipogenesis, to alleviate inflammation and endoplasmic reticulum stress, to ameliorate insulin resistance, and to attenuate liver injury. Because of these effects, activation of hepatic PPARβ/δ through synthetic or natural ligands provides a promising therapeutic option for the management of NAFLD.

Nuclear hormone and peptide hormone therapeutics for NAFLD and NASH

Background

Non-alcoholic steatohepatitis (NASH) is a spectrum of histological liver pathologies ranging from hepatocyte fat accumulation, hepatocellular ballooning, lobular inflammation, and pericellular fibrosis. Based on early investigations, it was discovered that visceral fat accumulation, hepatic insulin resistance, and atherogenic dyslipidemia are pathological triggers for NASH progression. As these pathogenic features are common with obesity, type 2 diabetes (T2D), and atherosclerosis, therapies that target dysregulated core metabolic pathways may hold promise for treating NASH, particularly as first-line treatments.

Scope of Review

In this review, the latest clinical data on nuclear hormone- and peptide hormone-based drug candidates for NASH are reviewed and contextualized, culminating with a discovery research perspective on emerging combinatorial therapeutic approaches that merge nuclear and peptide strategies.

Major Conclusion

Several drug candidates targeting the metabolic complications of NASH have shown promise in early clinical trials, albeit with unique benefits and challenges, but questions remain regarding their translation to larger and longer clinical trials, as well as their utility in a more diseased patient population. Promising polypharmacological approaches can potentially overcome some of these perceived challenges, as has been suggested in preclinical models, but deeper characterizations are required to fully evaluate these opportunities.

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Despite no approved treatments for NASH, several drug candidates have shown promise in early clinical trials.

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Therapies targeting metabolic pathologies of NASH have shown efficacy to reduce hepatic fat content and improve fibrosis.

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Many of these therapies have been rationally designed to mimic nuclear hormone or peptide hormone action.

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Despite provocative preclinical findings of nuclear and peptide hormone combination, clinical translation remains unproven.

The Selective Peroxisome Proliferator-Activated Receptor Gamma Modulator CHS-131 Improves Liver Histopathology and Metabolism in a Mouse Model of Obesity and Nonalcoholic Steatohepatitis

CHS-131 is a selective peroxisome proliferator-activated receptor gamma modulator with antidiabetic effects and less fluid retention and weight gain compared to thiazolidinediones in phase II clinical trials. We investigated the effects of CHS-131 on metabolic parameters and liver histopathology in a diet-induced obese (DIO) and biopsy-confirmed mouse model of nonalcoholic steatohepatitis (NASH). Male C57BL/6JRj mice were fed the amylin liver NASH diet (40% fat with trans-fat, 20% fructose, and 2% cholesterol). After 36 weeks, only animals with biopsy-confirmed steatosis and fibrosis were included and stratified into treatment groups (n = 12-13) to receive for the next 12 weeks (1) low-dose CHS-131 (10 mg/kg), (2) high-dose CHS-131 (30 mg/kg), or (3) vehicle. Metabolic parameters, liver pathology, metabolomics/lipidomics, markers of liver function and liver, and subcutaneous and visceral adipose tissue gene expression profiles were assessed. CHS-131 did not affect body weight, fat mass, lean mass, water mass, or food intake in DIO-NASH mice with fibrosis. CHS-131 improved fasting insulin levels and insulin sensitivity as assessed by the intraperitoneal insulin tolerance test. CHS-131 improved total plasma cholesterol, triglycerides, alanine aminotransferase, and aspartate aminotransferase and increased plasma adiponectin levels. CHS-131 (high dose) improved liver histology and markers of hepatic fibrosis. DIO-NASH mice treated with CHS-131 demonstrated a hepatic shift to diacylglycerols and triacylglycerols with a lower number of carbons, increased expression of genes stimulating fatty acid oxidation and browning, and decreased expression of genes promoting fatty acid synthesis, triglyceride synthesis, and inflammation in adipose tissue. Conclusion: CHS-131 improves liver histology in a DIO and biopsy-confirmed mouse model of NASH by altering the hepatic lipidome, reducing insulin resistance, and improving lipid metabolism and inflammation in adipose tissue.

Immunological distinctions between nonalcoholic steatohepatitis and hepatocellular carcinoma

Nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease, ranges from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is a more aggressive form characterized by hepatocyte injury, inflammation, and fibrosis. Increasing evidence suggests that NASH is a risk factor for hepatocellular carcinoma (HCC), which is the fifth most common cancer worldwide and the second most common cause of cancer-related death. Recent studies support a strong mechanistic link between the NASH microenvironment and HCC development. The liver has a large capacity to remove circulating pathogens and gut-derived microbial compounds. Thus, the liver is a central player in immunoregulation. Altered immune responses are tightly associated with the development of NASH and HCC. The objective of this study was to differentiate the roles of specific immune cell subsets in NASH and HCC pathogenesis.

Clarifying the role of specific cells in the immune system in the transition from non-alcoholic fatty liver disease (NAFLD) to liver cancer will help to understand disease progression and may open avenues towards new preventive and therapeutic strategies. NAFLD is the most common chronic liver disease. Growing evidence suggests that its most aggressive form, non-alcoholic steatohepatitis (NASH), can promote the development of liver cancer, the second most common cause of cancer deaths worldwide. Chang-Woo Lee and colleagues at Sungkyunkwan University, Suwon, South Korea review the immunological distinction between NASH and liver cancer, focusing on the levels and activities of six key types of immune system cells. Chronic inflammation mediated by the immune system can create conditions for NAFLD, NASH and liver cancer to develop and worsen.

Bile Acid Sequestrant, Sevelamer Ameliorates Hepatic Fibrosis with Reduced Overload of Endogenous Lipopolysaccharide in Experimental Nonalcoholic Steatohepatitis

Despite the use of various pharmacotherapeutic strategies, fibrosis due to nonalcoholic steatohepatitis (NASH) remains an unsatisfied clinical issue. We investigated the effect of sevelamer, a hydrophilic bile acid sequestrant, on hepatic fibrosis in a murine NASH model. Male C57BL/6J mice were fed a choline-deficient, L-amino acid-defined, high-fat (CDHF) diet for 12 weeks with or without orally administered sevelamer hydrochloride (2% per diet weight). Histological and biochemical analyses revealed that sevelamer prevented hepatic steatosis, macrophage infiltration, and pericellular fibrosis in CDHF-fed mice. Sevelamer reduced the portal levels of total bile acid and inhibited both hepatic and intestinal farnesoid X receptor activation. Gut microbiome analysis demonstrated that sevelamer improved a lower α-diversity and prevented decreases in Lactobacillaceae and Clostridiaceae as well as increases in Desulfovibrionaceae and Enterobacteriaceae in the CDHF-fed mice. Additionally, sevelamer bound to lipopolysaccharide (LPS) in the intestinal lumen and promoted its fecal excretion. Consequently, the sevelamer treatment restored the tight intestinal junction proteins and reduced the portal LPS levels, leading to the suppression of hepatic toll-like receptor 4 signaling pathway. Furthermore, sevelamer inhibited the LPS-mediated induction of fibrogenic activity in human hepatic stellate cells in vitro. Collectively, sevelamer inhibited the development of murine steatohepatitis by reducing hepatic LPS overload.