Obeticholic acid and INT-767 modulate collagen deposition in a NASH in vitro model

Novel preclinical developments of the primary sclerosing cholangitis treatment landscape

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease associated with inflammation, fibrosis, and destruction of intra- and extrahepatic bile ducts. Despite substantial recent advances in our understanding of PSC, the only proven treatment of PSC is liver transplantation. There is an urgent unmet need to find medical therapies for this disorder.

AREAS COVERED

Multiple drugs are currently under evaluation as therapeutic options for this disease. This article summarizes the literature on the various novel therapeutic options that have been investigated and are currently under development for the treatment of PSC.

EXPERT OPINION

In the next decade, more than one drug will likely be approved for the treatment of the disease, and we will be looking at combination therapies for the optimal management of the disease.

Characterization of diseased primary human hepatocytes in an all-human cell-based triculture system

Liver diseases, including NAFLD, are a growing worldwide health concern. Currently, there is a lack of suitable in vitro models that sustain basic primary human hepatocyte (PHH) morphology and functionality while supporting presentation of disease-associated phenotypic characteristics such as lipid accumulation and inflammasome activation. In TruVivo, an all-human triculture system (hTCS), basic metabolic functions were characterized in PHHs isolated from normal or diseased livers during two-weeks of culture. Decreases in albumin and urea levels and CYP3A4 activity were seen in diseased-origin PHHs compared to normal PHHs along with higher CYP2E1 expression. Positive expression of the macrophage markers CD68 and CD163 were seen in the diseased PHH preparations. Elevated levels of the pro-inflammatory cytokines IL-6 and MCP-1 and the fibrotic markers CK-18 and TGF-β were also measured. Gene expression of FASN, PCK1, and G6PC in the diseased PHHs was decreased compared to the normal PHHs. Further characterization revealed differences in lipogenesis and accumulation of intracellular lipids in normal and diseased PHHs when cultured with oleic acid and high glucose. TruVivo represents a promising new platform to study lipogenic mechanisms in normal and diseased populations due to the preservation of phenotypic differences over a prolonged culture period.

Obeticholic acid-loaded exosomes attenuate liver fibrosis through dual targeting of the FXR signaling pathway and ECM remodeling

End-stage of liver fibrosis as a precancerous state could lead to cirrhosis and hepatocellular carcinoma which liver transplantation is the only effective treatment. Previous studies have indicated that farnesoid X receptor (FXR) agonists, such as obeticholic acid (OCA) protect against hepatic injuries. However, free OCA administration results in side effects in clinical trials that could be alleviated by applying bio carriers such as MSC-derived exosomes (Exo) with the potential to mimic the biological regenerative effect of their parent cells, as proposed in this study. Loading OCA into the Exo was conducted via water bath sonication. Ex vivo bio distribution studies validated the Exo-loaded OCA more permanently accumulated in the liver. Using CCL4-induced liver fibrosis, we proposed whether Exo isolated from human Warton's Jelly mesenchymal stem cells loaded with a minimal dosage of OCA can facilitate liver recovery. Notably, Exo-loaded OCA exerted additive anti-fibrotic efficacy on histopathological features in CCL4-induced fibrotic mice. Compared to baseline, Exo-mediated delivery OCA results in marked improvements in the fibrotic-related indicators as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations. Accordingly, the synergistic impact of Exo-loaded OCA as a promising approach is associated with the inactivation of hepatic stellate cells (HSCs), extracellular matrix (ECM) remodeling, and Fxr-Cyp7a1 cascade on CCL4-induced liver fibrosis mice. In conclusion, our data confirmed the additive protective effects of Exo-loaded OCA in fibrotic mice, which suggests a valuable therapeutic strategy to combat liver fibrosis. Furthermore, the use of Exo for accurate drug delivery to the liver tissue can be inspiring.

Non-steroidal FXR agonist cilofexor improves cholestatic liver injury in the Mdr2-/- mouse model of sclerosing cholangitis

Background & Aims

The nuclear receptor farnesoid X receptor (FXR) is a key regulator of hepatic bile acid (BA) and lipid metabolism, inflammation and fibrosis. Here, we aimed to explore the potential of cilofexor (GS-9674), a non-steroidal FXR agonist, as a therapeutic approach for counteracting features of cholestatic liver injury by evaluating its efficacy and mechanisms in the Mdr2/Abcb4 knockout (-/-) mouse model of sclerosing cholangitis.

Methods

FVB/N wild-type and Mdr2-/- or BALB/c wild-type and Mdr2-/- mice were treated with 0, 10, 30 or 90 mg/kg cilofexor by gavage every 24 h for 10 weeks. Serum biochemistry, gene expression profile, hydroxyproline content, and picrosirius red and F4/80 immunostaining, were investigated. Bile flow, biliary bicarbonate and BA output, and hepatic BA profile, were assessed.

Results

Cilofexor treatment improved serum levels of aspartate aminotransferase, alkaline phosphatase as well as BAs in Mdr2-/- animals. Hepatic fibrosis was improved, as reflected by the reduced picrosirius red-positive area and hydroxyproline content in liver sections of cilofexor-treated Mdr2-/- mice. Intrahepatic BA concentrations were lowered in cilofexor-treated Mdr2-/- mice, while hepatobiliary bile flow and bicarbonate output were increased.

Conclusion

Collectively the current data show that cilofexor treatment improves cholestatic liver injury and decreases hepatic fibrosis in the Mdr2-/- mouse model of sclerosing cholangitis.

Impact and implications

Treatment with cilofexor, a non-steroidal farnesoid X receptor (FXR) agonist, improved histological features of sclerosing cholangitis, cholestasis and hepatic fibrosis in the Mdr2-/- mouse model. These findings indicate, that pharmacological stimulation of intestinal FXR-mediated gut-liver signaling, via fibroblast growth factor 15 (thereby reducing bile acid synthesis), may be sufficient to attenuate cholestatic liver injury in the Mdr2-/- mouse model of sclerosing cholangitis, thus arguing for potential therapeutic properties of cilofexor in cholestatic liver diseases.

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

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

Development of bile acid activated receptors hybrid molecules for the treatment of inflammatory and metabolic disorders

The farnesoid-x-receptor (FXR) and the G protein bile acid activated receptor (GPBAR)1 are two bile acid activated receptors highly expressed in entero-hepatic, immune, adipose and cardiovascular tissues. FXR and GPBAR1 are clinically validated targets in the treatment of metabolic disorders and FXR agonists are currently trialled in patients with non-alcoholic steato-hepatitis (NASH). Results of these trials, however, have raised concerns over safety and efficacy of selective FXR ligands suggesting that the development of novel agent designed to impact on multiple targets might have utility in the treatment of complex, multigenic, disorders. Harnessing on FXR and GPBAR1 agonists, several novel hybrid molecules have been developed, including dual FXR and GPBAR1 agonists and antagonists, while exploiting the flexibility of FXR agonists toward other nuclear receptors, dual FXR and peroxisome proliferators-activated receptors (PPARs) and liver-X-receptors (LXRs) and Pregnane-X-receptor (PXR) agonists have been reported. In addition, modifications of FXR agonists has led to the discovery of dual FXR agonists and fatty acid binding protein (FABP)1 and Leukotriene B4 hydrolase (LTB4H) inhibitors. The GPBAR1 binding site has also proven flexible to accommodate hybrid molecules functioning as GPBAR1 agonist and cysteinyl leukotriene receptor (CYSLTR)1 antagonists, as well as dual GPBAR1 agonists and retinoid-related orphan receptor (ROR)γt antagonists, dual GPBAR1 agonist and LXR antagonists and dual GPBAR1 agonists endowed with inhibitory activity on dipeptidyl peptidase 4 (DPP4). In this review we have revised the current landscape of FXR and GPBAR1 based hybrid agents focusing on their utility in the treatment of metabolic associated liver disorders.

Human Placental Mesenchymal Stem Cells Relieve Primary Sclerosing Cholangitis via Upregulation of TGR5 in Mdr2-/- Mice and Human Intrahepatic Cholangiocyte Organoid Models

Primary sclerosing cholangitis (PSC) is a biliary disease accompanied by chronic inflammation of the liver and biliary stricture. Mesenchymal stem cells (MSCs) are used to treat liver diseases because of their immune regulation and regeneration-promoting functions. This study was performed to explore the therapeutic potential of human placental MSCs (hP-MSCs) in PSC through the Takeda G protein-coupled receptor 5 (TGR5) receptor pathway. Liver tissues were collected from patients with PSC and healthy donors (n = 4) for RNA sequencing and intrahepatic cholangiocyte organoid construction. hP-MSCs were injected via the tail vein into Mdr2-/-, bile duct ligation (BDL), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse models or co-cultured with organoids to confirm their therapeutic effect on biliary cholangitis. Changes in bile acid metabolic profile were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Compared with healthy controls, liver tissues and intrahepatic cholangiocyte organoids from PSC patients were characterized by inflammation and cholestasis, and marked downregulation of bile acid receptor TGR5 expression. hP-MSC treatment apparently reduced the inflammation, cholestasis, and fibrosis in Mdr2-/-, BDL, and DDC model mice. By activating the phosphatidylinositol 3 kinase/extracellular signal-regulated protein kinase pathway, hP-MSC treatment promoted the proliferation of cholangiocytes, and affected the transcription of downstream nuclear factor κB through regulation of the binding of TGR5 and Pellino3, thereby affecting the cholangiocyte inflammatory phenotype.

The progress of molecules and strategies for the treatment of HBV infection

Hepatitis B virus infections have always been associated with high levels of mortality. In 2019, hepatitis B virus (HBV)-related diseases resulted in approximately 555,000 deaths globally. In view of its high lethality, the treatment of HBV infections has always presented a huge challenge. The World Health Organization (WHO) came up with ambitious targets for the elimination of hepatitis B as a major public health threat by 2030. To accomplish this goal, one of the WHO’s strategies is to develop curative treatments for HBV infections. Current treatments in a clinical setting included 1 year of pegylated interferon alpha (PEG-IFNα) and long-term nucleoside analogues (NAs). Although both treatments have demonstrated outstanding antiviral effects, it has been difficult to develop a cure for HBV. The reason for this is that covalently closed circular DNA (cccDNA), integrated HBV DNA, the high viral burden, and the impaired host immune responses all hinder the development of a cure for HBV. To overcome these problems, there are clinical trials on a number of antiviral molecules being carried out, all -showing promising results so far. In this review, we summarize the functions and mechanisms of action of various synthetic molecules, natural products, traditional Chinese herbal medicines, as clustered regularly interspaced short palindromic repeats and their associated proteins (CRISPR/Cas)-based systems, zinc finger nucleases (ZFNs), and transcription activator-like effector nucleases (TALENs), all of which could destroy the stability of the HBV life cycle. In addition, we discuss the functions of immune modulators, which can enhance or activate the host immune system, as well some representative natural products with anti-HBV effects.

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.

Mouse models of nonalcoholic fatty liver disease (NAFLD): pathomechanisms and pharmacotherapies

The prevalence of non-alcoholic fatty liver disease (NAFLD) increases year by year, and as a consequence, NAFLD has become one of the most prevalent liver diseases worldwide. Unfortunately, no pharmacotherapies for NAFLD have been approved by the United States Food and Drug Administration despite promising pre-clinical benefits; this situation highlights the urgent need to explore new therapeutic targets for NAFLD and for the discovery of effective therapeutic drugs. The mouse is one of the most commonly used models to study human disease and develop novel pharmacotherapies due to its small size, low-cost and ease in genetic engineering. Different mouse models are used to simulate various stages of NAFLD induced by dietary and/or genetic intervention. In this review, we summarize the newly described patho-mechanisms of NAFLD and review the preclinical mouse models of NAFLD (based on the method of induction) and appraises the use of these models in anti-NAFLD drug discovery. This article will provide a useful resource for researchers to select the appropriate model for research based on the research question being addressed.

Targeting bile acid signaling for the treatment of liver diseases: From bench to bed

Liver diseases and related complications have become one of the leading causes of morbidity and mortality worldwide, yet effective medicine or approved treatment approach is still limited. Thus, novel therapy is urgently required to prevent or at least slow down the growing burden of liver transplantation or even death caused by malignant liver diseases. As the irreplaceable modulator of hepatic and intestinal signaling cascades, bile acids (BAs) play complex physiological as well as pathological roles in regulating energy and immune homeostasis in various liver diseases, including but not limited to metabolic diseases and cholangiopathies, making them highly attractive therapeutic targets. In the current review, recent progress in the research of enterohepatic circulation of BAs and potential therapeutic targets of BAs signaling, especially the development of currently available treatments, including agonizts of FXR and TGR5, analogs of FGF19, inhibitors of ASBT, and the regulation of gut microbiome through fecal microbiota transplantation were extensively summarized. Their protective effects, molecular mechanisms, and outcomes of clinical trials were highlighted. The structural features of these candidates and perspectives for their future development were further discussed. In conclusion, we believe that pharmacological therapies targeting BAs signaling represent promising and efficient strategies for the treatment of complex and multifactorial liver disorders.

Farnesoid X Receptor, Bile Acid Metabolism, and Gut Microbiota

Obesity, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD) are characterized by the concepts of lipo- and glucotoxicity. NAFLD is characterized by the accumulation of different lipidic species within the hepatocytes. Bile acids (BA), derived from cholesterol, and conjugated and stored in the gallbladder, help the absorption/processing of lipids, and modulate host inflammatory responses and gut microbiota (GM) composition. The latter is the new "actor" that links the GI tract and liver in NAFLD pathogenesis. In fact, the discovery and mechanistic characterization of hepatic and intestinal farnesoid X receptor (FXR) shed new light on the gut-liver axis. We conducted a search on the main medical databases for original articles, reviews, meta-analyses of randomized clinical trials, and case series using the following keywords, their acronyms, and their associations: farnesoid X receptor, bile acids metabolism, gut microbiota, dysbiosis, and liver steatosis. Findings on the synthesis, metabolism, and conjugation processes of BAs, and their action on FXR, change the understanding of NAFLD physiopathology. In detail, BAs act as ligands to several FXRs with GM modulation. On the other hand, the BAs pool is modulated by GM, thus, regulating FXRs functioning in the frame of liver fat deposition and fibrosis development. In conclusion, BAs passed from their role of simple lipid absorption and metabolism agents to messengers between the gut and liver, modulated by GM.

New Drugs for Hepatic Fibrosis

The morbidity and mortality of hepatic fibrosis caused by various etiologies are high worldwide, and the trend is increasing annually. At present, there is no effective method to cure hepatic fibrosis except liver transplantation, and its serious complications threaten the health of patients and cause serious medical burdens. Additionally, there is no specific drug for the treatment of hepatic fibrosis, and many drugs with anti-hepatic fibrosis effects are in the research and development stage. Recently, remarkable progress has been made in the research and development of anti-hepatic fibrosis drugs targeting different targets. We searched websites such as PubMed, ScienceDirect, and Home-ClinicalTrials.gov and found approximately 120 drugs with anti-fibrosis properties, some of which are in phase Ⅱ or Ⅲ clinical trials. Additionally, although these drugs are effective against hepatic fibrosis in animal models, most clinical trials have shown poor results, mainly because animal models do not capture the complexity of human hepatic fibrosis. Besides, the effect of natural products on hepatic fibrosis has not been widely recognized at home and abroad. Furthermore, drugs targeting a single anti-hepatic fibrosis target are prone to adverse reactions. Therefore, currently, the treatment of hepatic fibrosis requires a combination of drugs that target multiple targets. Ten new drugs with potential for development against hepatic fibrosis were selected and highlighted in this mini-review, which provides a reference for clinical drug use.

Obeticholic Acid Reduces Kidney Matrix Metalloproteinase Activation following Partial Hepatic Ischemia/Reperfusion Injury in Rats

We have previously demonstrated that the farnesoid X receptor (FXR) agonist obeticholic acid (OCA) protects the liver via downregulation of hepatic matrix metalloproteinases (MMPs) after ischemia/reperfusion (I/R), which can lead to multiorgan dysfunction. The present study investigated the capacity of OCA to modulate MMPs in distant organs such as the kidney. Male Wistar rats were dosed orally with 10 mg/kg/day of OCA (5 days) and were subjected to 60-min partial hepatic ischemia. After 120-min reperfusion, kidney biopsies (cortex and medulla) and blood samples were collected. Serum creatinine, kidney MMP-2, and MMP-9-dimer, tissue inhibitors of MMPs (TIMP-1, TIMP-2), RECK, TNF-alpha, and IL-6 were monitored. MMP-9-dimer activity in the kidney cortex and medulla increased after hepatic I/R and a reduction was detected in OCA-treated I/R rats. Although not significantly, MMP-2 activity decreased in the cortex of OCA-treated I/R rats. TIMPs and RECK levels showed no significant differences among all groups considered. Serum creatinine increased after I/R and a reduction was detected in OCA-treated I/R rats. The same trend occurred for tissue TNF-alpha and IL-6. Although the underlying mechanisms need further investigation, this is the first study showing, in the kidney, beneficial effects of OCA by reducing TNF-alpha-mediated expression of MMPs after liver I/R.

The Beneficial Effects of Triterpenic Acid and Acteoside in an In Vitro Model of Nonalcoholic Steatohepatitis (NASH)

Triterpenic acid (TA) and acteoside (ACT), the major components of APPLIVER and ACTEOS, respectively, have been reported to exert hepatoprotective effects, but the molecular mechanisms remain elusive, particularly in the NAFLD/NASH context. We assessed their effects in our well-established in vitro model resembling the pathophysiological mechanisms involved in NASH. Human hepatocytes and hepatic stellate cells were exposed to free fatty acids (FFA) alone or in combination with APPLIVER and ACTEOS as a mono- or co-culture. Steatosis, inflammation, generation of reactive oxygen species (ROS), and collagen deposition were determined. ACTEOS reduced both the TNF-α and ROS production, and, most importantly, attenuated collagen deposition elicited by the excess of FFA in the co-culture model. APPLIVER also showed inhibition of both TNF-α production and collagen deposition caused by FFA accumulation. The compounds alone did not induce any cellular effects. The present study showed the efficacy of APPLIVER and ACTEOS on pathophysiological mechanisms related to NASH. These in vitro data suggest that these compounds deserve further investigation for possible use in NASH treatment.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

Multi-Target Drugs for Kidney Diseases

Kidney diseases such as AKI, CKD, and GN can lead to dialysis and the need for kidney transplantation. The pathologies for kidney diseases are extremely complex, progress at different rates, and involve several cell types and cell signaling pathways. Complex kidney diseases require therapeutics that can act on multiple targets. In the past 10 years, in silico design of drugs has allowed for multi-target drugs to progress quickly from concept to reality. Several multi-target drugs have been made successfully to target AA pathways and transcription factors for the treatment of inflammatory, fibrotic, and metabolic diseases. Multi-target drugs have also demonstrated great potential to treat diabetic nephropathy and fibrotic kidney disease. These drugs act by decreasing renal TGF-β signaling, inflammation, mitochondrial dysfunction, and oxidative stress. There are several other recently developed multi-target drugs that have yet to be tested for their ability to combat kidney diseases. Overall, there is excellent potential for multi-target drugs that act on several cell types and signaling pathways to treat kidney diseases.

Synthesis of 12β-Methyl-18-nor-bile Acids

Decoupling the roles of the farnesoid X nuclear receptor and Takeda G-protein-coupled bile acid receptor 5 is essential for the development of novel bile acid therapeutics targeting metabolic and neurodegenerative diseases. Herein, we describe the synthesis of 12β-methyl-18-nor-bile acids which may serve as probes in the search for new bile acid analogues with clinical applicability. A Nametkin-type rearrangement was applied to protected cholic acid derivatives, giving rise to tetra-substituted Δ13,14- and Δ13,17-unsaturated 12β-methyl-18-nor-bile acid intermediates (24a and 25a). Subsequent catalytic hydrogenation and deprotection yielded 12β-methyl-18-nor-chenodeoxycholic acid (27a) and its 17-epi-epimer (28a) as the two major reaction products. Optimization of the synthetic sequence enabled a chromatography-free route to prepare these bile acids at a multi-gram scale. In addition, the first cis-C-D ring-junctured bile acid and a new 14(13 → 12)-abeo-bile acid are described. Furthermore, deuteration experiments were performed to provide mechanistic insights into the formation of the formal anti-hydrogenation product 12β-methyl-18-nor-chenodeoxycholic acid (27a).

Nuclear Receptors in Liver Fibrosis

Nuclear receptors are ligand-activated transcription factors that regulate gene expression of a variety of key molecular signals involved in liver fibrosis. The primary cellular driver of liver fibrogenesis are activated hepatic stellate cells. Different NRs regulate the hepatic expression of pro-inflammatory and pro-fibrogenic cytokines that promote the transformation of hepatic stellate cells into fibrogenic myofibroblasts. Importantly, nuclear receptors regulate gene expression circuits that promote hepatic fibrogenesis and/or allow liver fibrosis regression. In this review, we highlight the direct and indirect influence of nuclear receptors on liver fibrosis, with a focus on hepatic stellate cells, and discuss potential therapeutic effects of nuclear receptor modulation in regard to anti-fibrotic and anti-inflammatory effects. Further research on nuclear receptors-related signaling may lead to the clinical development of effective anti-fibrotic therapies for patients with liver disease.

Abnormal Metabolism in the Progression of Nonalcoholic Fatty Liver Disease to Hepatocellular Carcinoma: Mechanistic Insights to Chemoprevention

Nonalcoholic fatty liver disease (NAFLD) is on the rise and becoming a major contributor to the development of hepatocellular carcinoma (HCC). Reasons for this include the rise in obesity and metabolic syndrome in contrast to the marked advances in prevention and treatment strategies of viral HCC. These shifts are expected to rapidly propel this trend even further in the coming decades, with NAFLD on course to become the leading etiology of end-stage liver disease and HCC. No Food and Drug Administration (FDA)-approved medications are currently available for the treatment of NAFLD, and advances are desperately needed. Numerous medications with varying mechanisms of action targeting liver steatosis and fibrosis are being investigated including peroxisome proliferator-activated receptor (PPAR) agonists and farnesoid X receptor (FXR) agonists. Additionally, drugs targeting components of metabolic syndrome, such as antihyperglycemics, have been found to affect NAFLD progression and are now being considered in the treatment of these patients. As NAFLD drug discovery continues, special attention should be given to their relationship to HCC. Several mechanisms in the pathogenesis of NAFLD have been implicated in hepatocarcinogenesis, and therapies aimed at NAFLD may additionally harbor independent antitumorigenic potential. This approach may provide novel prevention and treatment strategies.

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.

An insight into primary biliary cholangitis and its recent advances in treatment: semi-synthetic analogs to combat ursodeoxycholic-acid resistance

INTRODUCTION

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease which on progression causes cirrhosis; various studies also suggested that several diseases can co-exist in patients. In existing depiction of disease PBC, apart from entire use of ursodeoxycholic acid (UDCA), several patients need to step forward to liver-transplantation or death due to resistance or non-responder with UDCA monotherapy.

AREAS COVERED

To overcome this non-respondent treatment, novel bile acid semi-synthetic analogs have been identified which shows their potency against for farnesoid X receptor and transmembrane G protein-coupled receptor-5 which are identified as target for many developing analogs which have desirable pharmacokinetic profiles.

EXPERT OPINION

A range of studies suggests that adding semisynthetic analogs in therapeutic regime improves liver biochemistries in patients with suboptimal response to UDCA. Thus, the aspire of this review is to abridge and compare therapeutic value and current markets affirm of various bile acids semi-synthetic analogs which certainly are having promising effects in PBC monotherapy or in pooled treatment with UDCA for PBC.

Sex differences in non-alcoholic fatty liver disease: hints for future management of the disease

Non-alcoholic fatty liver disease (NAFLD) remains a major cause of chronic liver disease worldwide. Despite extensive studies, the heterogeneity of the risk factors as well as different disease mechanisms complicate the goals toward effective diagnosis and management. Recently, it has been shown that sex differences play a role in the prevalence and progression of NAFLD. In vitro, in vivo, and clinical studies revealed that the lower prevalence of NAFLD in premenopausal as compared to postmenopausal women and men is mainly due to the protective effects of estrogen and body fat distribution. It has been also described that males and females present differential pathogenic features in terms of biochemical profiles and histological characteristics. However, the exact molecular mechanisms for the gender differences that exist in the pathogenesis of NAFLD are still elusive. Lipogenesis, oxidative stress, and inflammation play a key role in the progression of NAFLD. For NAFLD, only a few studies characterized these mechanisms at the molecular level. Therefore, we aim to review the reported differential molecular mechanisms that trigger such different pathogenesis in both sexes. Differences in lipid metabolism, glucose homeostasis, oxidative stress, inflammation, and fibrosis were discussed based on the evidence reported in recent publications. In conclusion, with this review, we hope to provide a new perspective for the development of future practice guidelines as well as a new avenue for the management of the disease.