Combination Therapy of All-Trans Retinoic Acid With Ursodeoxycholic Acid in Patients With Primary Sclerosing Cholangitis: A Human Pilot Study

Molecular insights into experimental models and therapeutics for cholestasis

Cholestatic liver disease (CLD) is a range of conditions caused by the accumulation of bile acids (BAs) or disruptions in bile flow, which can harm the liver and bile ducts. To investigate its pathogenesis and treatment, it is essential to establish and assess experimental models of cholestasis, which have significant clinical value. However, owing to the complex pathogenesis of cholestasis, a single modelling method can merely reflect one or a few pathological mechanisms, and each method has its adaptability and limitations. We summarize the existing experimental models of cholestasis, including animal models, gene-knockout models, cell models, and organoid models. We also describe the main types of cholestatic disease simulated clinically. This review provides an overview of targeted therapy used for treating cholestasis based on the current research status of cholestasis models. In addition, we discuss the respective advantages and disadvantages of different models of cholestasis to help establish experimental models that resemble clinical disease conditions. In sum, this review not only outlines the current research with cholestasis models but also projects prospects for clinical treatment, thereby bridging basic research and practical therapeutic applications.

Navigating the liver landscape: upcoming pharmacotherapies for primary sclerosing cholangitis

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Fat malabsorption in short bowel syndrome: A review of pathophysiology and management

Fat malabsorption is central to the pathophysiology of short bowel syndrome (SBS). It occurs in patients with insufficient intestinal surface area and/or function to maintain metabolic and growth demands. Rapid intestinal transit and impaired bile acid recycling further contribute to fat malabsorption. A significant portion of patients require parenteral nutrition (PN) for their survival but may develop sepsis and liver dysfunction as a result. Despite advancements in the treatment of SBS, fat malabsorption remains a chronic issue for this vulnerable patient population. Peer-reviewed literature was assessed on the topic of fat malabsorption in SBS. Current management of patients with SBS involves dietary considerations, PN management, antidiarrheals, glucagon-like peptide 2 agonists, and multidisciplinary teams. Clinical trials have focused on improving intestinal fat absorption by facilitating fat digestion with pancreatic enzymes. Targeting fat malabsorption in SBS is a potential pathway to improving lifestyle and reducing morbidity and mortality in this rare disease.

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.

An overview of recent treatment options for primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic hepatic dysfunction characterized by inflammatory and tissue-degenerative strictures of the biliary tree, leading to cirrhosis and cholangiocarcinoma. The pathophysiological mechanisms involve immune-mediated responses. Numerous treatment modalities targeting the inflammatory aspects have been suggested, but a consensus on the best treatment option is lacking. This study aims to review the most up-to-date treatment options for PSC.

Current Therapeutics in Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is an orphan, cholestatic liver disease that is characterized by inflammatory biliary strictures with variable progression to end-stage liver disease. Its pathophysiology is poorly understood. Chronic biliary inflammation is likely driven by immune dysregulation, gut dysbiosis, and environmental exposures resulting in gut-liver crosstalk and bile acid metabolism disturbances. There is no proven medical therapy that alters disease progression in PSC, with the commonly prescribed ursodeoxycholic acid being shown to improve liver biochemistry at low-moderate doses (15-23 mg/kg/day) but not alter transplant-free survival or liver-related outcomes. Liver transplantation is the only option for patients who develop end-stage liver disease or refractory complications of PSC. Immunosuppressive and antifibrotic agents have not proven to be effective, but there is promise for manipulation of the gut microbiome with fecal microbiota transplantation and antibiotics. Bile acid manipulation via alternate synthetic bile acids such as norursodeoxycholic acid, or interaction at a transcriptional level via nuclear receptor agonists and fibrates have shown potential in phase II trials in PSC with several leading to larger phase III trials. In view of the enhanced malignancy risk, statins, and aspirin show potential for reducing the risk of colorectal cancer and cholangiocarcinoma in PSC patients. For patients who develop clinically relevant strictures with cholestatic symptoms and worsening liver function, balloon dilatation is safer compared with biliary stent insertion with equivalent clinical efficacy.

Pediatric Autoimmune or Primary Sclerosing Cholangitis: Metronidazole Effectiveness on Biochemical Data, Bile Acid Profile, and Gut Microbiota: A Pilot Study

Objectives

Autoimmune hepatitis and primary sclerosing cholangitis (PSC) can both be present, resulting in autoimmune sclerosing cholangitis (ASC). PSC physiopathology could be based on the cross-talk between gut microbiota and bile acids (BAs); antibiotics are an innovative therapy. This pilot study assesses metronidazole (MTZ)'s effectiveness in ASC or PSC patients according to the stage of the disease, and its effects on biochemical parameters, BA profiles, and gut microbiota.

Methods

ASC or PSC patients from Cliniques universitaires Saint-Luc's pediatric hepato-gastroenterology division were enrolled retrospectively and prospectively; both datasets were merged. MTZ was administered over at least 14 days on top of standard treatment (ursodeoxycholic acid, azathioprine, and steroids). Fecal and blood samples were collected before (T0) and at MTZ day 14 (T14). Sustained biochemical remission was defined by the reduction of transaminases (AST and ALT), gamma-glutamyl transferase (GGT), and CRP until 12 months post-MTZ.

Results

A total of 18 patients (mean age, 13.2 ± 4.5 years) were enrolled (13 ASC and 5 PSC), and divided in remission or relapse patients. CRP, AST, ALT, and GGT levels decreased post-MTZ in both groups (excepting GGT in relapse patients), with decreases between T0 and T14 being significant for AST and ALT. Relapse patients were older (P = 0.0351) and in late-disease stage, with mainly large-duct PSC (P = 0.0466). In remission patients, the mean plasma relative abundance of hydrophilic BA increased by +6.3% (P = 0.0391) after MTZ. Neither at baseline nor T14, there were significant differences in gut microbiota recorded.

Conclusion

These data are likely indicative of long-term benefits following MTZ therapy at early-stage ASC or PSC, with increased hydrophilic BA abundance. Multicenter prospective studies are needed.

The gut-liver axis in cholangiopathies: focus on bile acid based pharmacological treatment

PURPOSE OF REVIEW

This review analyses the main features of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) and provides an overview of the currently available (bile acid) bile acid related treatments.

RECENT FINDINGS

In PBC, biliary injury is the consequence of a dysregulated intrahepatic and systemic immune response. Given the close association between PSC and inflammatory bowel disease (IBD), the microbiota represents an important factor in the development of PSC. Bile acid based pharmacological treatments could represent promising therapeutic strategies in the management of cholangiopathies.

SUMMARY

Cholangiopathies include a spectrum of diseases resulting in cholestasis, an impairment of bile flow in the biliary tree, leading to biliary obstruction and damage as well as liver inflammation and fibrosis. PSC and PBC are highly heterogeneous cholangiopathies and progressive disorders with defined pathophysiological mechanisms. Curative treatments have not been established, and although their prevalence is low, they are a frequent indication for liver transplantation in the advanced stages of cholangiopathies. These diseases still present with unmet therapeutic strategies, also taking into account that on average 30-40% of patients undergoing liver transplantation will have recurrence of the original illness.

An Update on Novel Pharmacological Agents for Primary Sclerosing Cholangitis

INTRODUCTION

: Primary sclerosing cholangitis (PSC) is a rare chronic cholestatic liver disease with heterogeneous phenotypes that may lead to liver transplantation and/or end-stage liver disease. Its multifactorial etiopathogenesis remains uncertain, but gut-liver axis and bile composition and excretion are widely demonstrated to influence the immune-mediated fibrogenic reactive cascade.

AREAS COVERED

: Different experimental therapeutic options are under investigation, mainly aiming at modulating bile acids excretion, limiting inflammatory-cascade reactions, and changing intestinal microbiota composition; none of them yet demonstrated to prolong transplant free survival.

This review provides a comprehensive description of the experimental drugs recently tested and/or currently under investigation. A bibliographical search was performed in Pubmed, MEDLINE, EMBASE, OVID and clinicaltrial.gov until July 2021.

EXPERT OPINION

: The heterogeneity and poor prevalence of PSC, its uncertain pathophysiology, and the lack of surrogate endpoints are the major challenges in drug discovery. Strategies that synergistically target microbiota, bile acids, and liver fibrosis are needed. In parallel, we must enhance biomarker discovery to develop surrogate endpoints, as biochemical markers' fluctuations over the time hamper their effectiveness. Magnetic resonance cholangiopancreatography tools that accurately measure bile duct changes represent a potential, novel marker for disease monitoring. A collaboration between academia, research consortia, patient's associations and industry is required.

A Current Understanding of Bile Acids in Chronic Liver Disease

Chronic liver disease (CLD) is one of the leading causes of disability-adjusted life years in many countries. A recent understanding of nuclear bile acid receptor pathways has increased focus on the impact of crosstalk between the gut, bile acids, and liver on liver pathology. While conventionally used in cholestatic disorders and to dissolve gallstones, the discovery of bile acids' influence on the gut microbiome and human metabolism offers a unique potential for their utility in early and advanced liver diseases because of diverse etiologies. Based on these findings, preclinical studies using bile acid-based molecules have shown encouraging results at addressing liver inflammation and fibrosis. Emerging data also suggest that bile acid profiles change distinctively across various causes of liver disease. We summarize the current knowledge and evidence related to bile acids in health and disease and discuss culminated and ongoing therapeutic trials of bile acid derivatives in CLD. In the near future, further evidence in this area might help clinicians better detect and manage liver diseases.

Emerging drugs for the treatment of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a rare immune-mediated cholestatic disease for which no medical therapy has been shown to slow disease progression. Consequently, liver transplantation is the only lifesaving intervention for patients, and despite being a rare disease, PSC is the lead indication for transplantation across several European countries. The vast majority of patients (>70%) also develop inflammatory bowel disease (IBD) at some point in their lifetime, which imparts added lifetime risks of hepatobiliary malignancy and colorectal cancer. The rare disease nature, variable and often slow rates of disease progression (years rather than months), and lack of robust surrogate biomarkers for early stage yet high risk disease, represent critical challenges in trial design that have long precluded the development of effective medical treatment. However, the horizon for new treatments is encouraging, given innovative clinical trial programmes led by industry, alongside several investigator-initiated studies. Herein, we outline the current platform of interventional trials in PSC, before discussing emerging areas of therapeutic interest.

Treatment of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by progressive fibro-stenotic strictures and destruction of the biliary tree. Currently, there is no effective treatment which can delay its progression or ameliorate the transplant-free survival. Moreover, a major chontroversy in PSC is whether to use UDCA. More recently, novel pharmacological agents emerged aiming at: i) modulation of bile composition; ii) immunomodulation; iii) targeting the gut microbiome; iv) targeting fibrosis. Successful PSC therapy, however, will be most likely a personalized combination of different drugs plus endoscopic treatment. This review aims at offering an overview on the experimental pharmacological strategies currently exploited for PSC treatment.

Therapeutic targets, novel drugs, and delivery systems for diabetes associated NAFLD and liver fibrosis

Type 2 diabetes mellitus (T2DM) associated non-alcoholic fatty liver disease (NAFLD) is the fourth-leading cause of death. Hyperglycemia induces various complications, including nephropathy, cirrhosis and eventually hepatocellular carcinoma (HCC). There are several etiological factors leading to liver disease development, which involve insulin resistance and oxidative stress. Free fatty acid (FFA) accumulation in the liver exerts oxidative and endoplasmic reticulum (ER) stresses. Hepatocyte injury induces release of inflammatory cytokines from Kupffer cells (KCs), which are responsible for activating hepatic stellate cells (HSCs). In this review, we will discuss various molecular targets for treating chronic liver diseases, including homeostasis of FFA, lipid metabolism, and decrease in hepatocyte apoptosis, role of growth factors, and regulation of epithelial-to-mesenchymal transition (EMT) and HSC activation. This review will also critically assess different strategies to enhance drug delivery to different cell types. Targeting nanocarriers to specific liver cell types have the potential to increase efficacy and suppress off-target effects.

Bile acid-farnesoid X receptor-fibroblast growth factor 19 axis in patients with short bowel syndrome: The randomized, glepaglutide phase 2 trial

BACKGROUND

The gut-liver axis and enterohepatic circulation have gained increasing attention lately. Patients with short bowel syndrome (SBS) are, in fact, human knock-out models that may assist in the understanding of bile acid synthesis and regulation. We evaluated effect of glepaglutide (a long-acting glucagon-like peptide-2 analog) on bile acid synthesis (the enterohepatic circulation of bile acids and liver biochemistry in patients with SBS).

METHOD

In a single-center, double-blinded, dose-finding, crossover phase 2 trial, 18 patients with SBS were randomly assigned to 2 of 3 treatment arms (0.1, 1, and 10 mg) with daily subcutaneous injections of glepaglutide for 3 weeks. The washout period between the 2 treatment periods was 4-8 weeks. Measurements were performed at baseline and at the end of each treatment period and included postprandial plasma samples for fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), total excretion of fecal bile acids, gene expression of farnesoid X receptor (FXR) in intestinal mucosal biopsies, total plasma bile acids, and liver biochemistry.

RESULTS

Compared with baseline, the median (interquartile range) postprandial response (area under the curve 0-2h) of FGF19 increased by 150 h × ng/L (41, 195; P = 0.001) and C4 decreased by 82 h × µg/L (-169, -28; p = 0.010) in the 10-mg dose. FXR gene expression did not change in any of the groups. Alkaline phosphatase significantly decreased.

CONCLUSION

Glepaglutide may stimulate the bile acid/FXR/FGF19 axis, leading to increased plasma concentrations of FGF19. Thereby, glepaglutide may ameliorate the accelerated de novo bile acid synthesis and play a role in the prevention and/or treatment of intestinal failure-associated liver disease.

Fibrotic Events in the Progression of Cholestatic Liver Disease

Cholestatic liver diseases including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are associated with active hepatic fibrogenesis, which can ultimately lead to the development of cirrhosis. However, the exact relationship between the development of liver fibrosis and the progression of cholestatic liver disease remains elusive. Periductular fibroblasts located around the bile ducts seem biologically different from hepatic stellate cells (HSCs). The fibrotic events in these clinical conditions appear to be related to complex crosstalk between immune/inflammatory mechanisms, cytokine signalling, and perturbed homeostasis between cholangiocytes and mesenchymal cells. Several animal models including bile duct ligation (BDL) and the Mdr2-knockout mice have improved our understanding of mechanisms underlying chronic cholestasis. In the present review, we aim to elucidate the mechanisms of fibrosis in order to help to identify potential diagnostic and therapeutic targets.

The role of the retinoid receptor, RAR/RXR heterodimer, in liver physiology

Activated by retinoids, metabolites of vitamin A, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs) play important roles in a wide variety of biological processes, including embryo development, homeostasis, cell proliferation, differentiation and death. In this review, we summarized the functional roles of nuclear receptor RAR/RXR heterodimers in liver physiology. Specifically, RAR/RXR modulate the synthesis and metabolism of lipids and bile acids in hepatocytes, regulate cholesterol transport in macrophages, and repress fibrogenesis in hepatic stellate cells. We have also listed the specific genes that carry these functions and how RAR/RXR regulate their expression in liver cells, providing a mechanistic view of their roles in liver physiology. Meanwhile, we pointed out many questions regarding the detailed signaling of RAR/RXR in regulating the expression of liver genes, and hope future studies will address these issues.

The Management of Cholestatic Liver Diseases: Current Therapies and Emerging New Possibilities

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are two chronic cholestatic liver diseases affecting bile ducts that may progress to biliary cirrhosis. In the past few years, the increasing knowledge in the pathogenesis of both diseases led to a growing number of clinical trials and possible new targets for therapy. In this review, we provide an update on the treatments in clinical use and summarize the new drugs in trials for PBC and PSC patients. Farnesoid X Receptor (FXR) agonists and Pan-Peroxisome Proliferator-Activated Receptor (PPAR) agonists are the most promising agents and have shown promising results in both PBC and PSC. Fibroblast Growth Factor 19 (FGF19) analogues also showed good results, especially in PBC, while, although PBC and PSC are autoimmune diseases, immunosuppressive drugs had disappointing effects. Since the gut microbiome could have a potential role in the pathogenesis of PSC, recent research focused on molecules that could change the microbiome, with good results. The near future of the medical management of these diseases may include new treatments or a combination of multiple drugs targeting different signaling pathways at different stages of the diseases.

Recent advances in the treatment of primary sclerosing cholangitis

Introduction: PSC is a rare liver disease that leads frequently to cirrhosis and need for liver transplantation. No medical treatment is of proven value. Liver transplantation is the only curative therapy available. There is a big medical need to find medical therapy that can alter the natural history of the disease.Areas covered: The authors highlight advances in PSC, based on recent literature retrieved from PubMed until September 2020 regarding both medical and endoscopic biliary therapy.Future possibilities for treatment of PSC are discussed.Expert opinion: Biliary endoscopy is the cornerstone in the treatment of dominant strictures. Single-user peroral cholangioscopy is an emerging modality. Balloon dilatation therapy is the treatment of choice of dominant strictures. The most promising medical therapies showing efficacy in phase II trials are nor-Ursodeoxycholic acid, obethicolic acid, the non-steroidal FXR agonist Cilofexor and Aldafermin, a synthetic analogue of FGF-19. Antibiotics, particularly vancomycin have shown potential benefits, particularly in children but phase III studies are lacking. In observational studies of effects of biological therapy in patients with IBD/PSC adalimumab was associated with reduction in ALP. Results of liver transplantation are favorable but recurrence can be of clinical relevance particularly in patients transplanted before the age of 40.

Multiple therapeutic targets in rare cholestatic liver diseases: Time to redefine treatment strategies

Primary biliary cholangitis and primary sclerosing cholangitis are rare diseases affecting the bile ducts and the liver. The limited knowledge of their pathogenesis leads to limited therapeutic options. Nevertheless, the landscape of novel therapies for these cholangiopathies is now rapidly changing, providing new treatment opportunities for patients and clinicians involved in their care. The aim of this review is to summarize the evidence of novel molecules under investigation for primary biliary cholangitis and primary sclerosing cholangitis and to discuss how they can potentially change current treatment paradigms.

Review: Pathogenesis of cholestatic liver diseases

Cholestatic liver diseases (CLD) begin to develop after an impairment of bile flow start to affect the biliary tree. Cholangiocytes actively participate in the liver response to injury and repair and the intensity of this reaction is a determinant factor for the development of CLD. Progressive cholangiopathies may ultimately lead to end-stage liver disease requiring at the end orthotopic liver transplantation. This narrative review will discuss cholangiocyte biology and pathogenesis mechanisms involved in four intrahepatic CLD: Primary biliary cholangitis, primary sclerosing cholangitis, cystic fibrosis involving the liver, and polycystic liver disease.

Gut microbiome in primary sclerosing cholangitis: A review

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by biliary inflammation and stricturing. Exploration of the pathogenesis of PSC in light of its association with inflammatory bowel disease (IBD) and the “gut-liver” axis is an emerging area of interest. A growing number of studies have begun to elucidate the role of the gut microbiota, its metabolites and its influence on host immune responses in the development of PSC and PSC-IBD. Studies of the fecal microbiota have highlighted enriched levels of certain species, including Veillonella, Streptococcus and Enterococcus, among others. A heightened immune response to enteric dysbiosis and bacterial translocation have also been implicated. For example, Klebsiella pneumoniae strains derived from gnotobiotic mice transplanted with PSC-IBD microbiota were found to induce pore formation in human intestinal epithelial cells and enhanced Th17 responses. Gut microbes have additionally been hypothesized to be implicated in PSC pathogenesis through their role in the synthesis of various metabolites, including bile acids (BAs), which function as signaling molecules with important gut and hepatic effects. An expanded knowledge of the gut microbiome as it relates to PSC offers critical insight into the development of microbe-altering therapeutic interventions, such as antibiotics, nutritional interventions and fecal microbial transplantation. Some of these have already shown some preliminary evidence of benefit. Despite exciting progress in the field, much work remains to be done; areas that are particularly lacking include functional characterization of the microbiome and examination of pediatric populations. In this review, we summarize studies that have investigated the microbiome in PSC and PSC-IBD as well as putative mechanisms, including the potential role of metabolites, such as BAs. We then briefly review the evidence for interventions with microbe-altering properties for treating PSC.

Novel Therapies for Managing Cholestasis

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Protective Effects of Ursodeoxycholic Acid on Valproic Acid Induced Hepatotoxicity in Epileptic Children with Recurrent Seizure; A Double-Blinded Randomized Clinical Trial

Background : There are controversies regarding the protective role of ursodeoxycholic acid (UDCA) against valproic acid (VPA)-induced hepatotoxicity in children. In the present clinical trial, we assessed the potential role of UDCA in preventing VPA-induced fluctuations of hepatic enzymes in epileptic children with recurrent seizures. Methods: Two-hundred children with epileptic seizures were randomly allocated into either intervention (VPA+UDCA) or control (VPA+ placebo) group. Fluctuations of liver enzymes were recorded at baseline, as well as 48 hours, 1 month, and 3 months following the interventions. Results: The mean age of the patients was 7.33±2.96 years (the range of 4-16). Males and females constituted 43 (43%) and 57 (57%) subjects in each group respectively. There were no significant differences in the baseline levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) between the intervention and control groups. At 48 hours post-intervention, AST and ALT increased 1.7% and 11.05% (23.18±7.91 and 30.75±4.20 IU/l) in the intervention group and 21.3% and 35% (28.46±3.71 and 35.62±7.72 IU/l) in the control group respectively (P<0.0001). Both AST (P<0.001) and ALT (P=0.03) levels were significantly lower in the intervention than placebo group at 1-month post-intervention. At 3-month post-intervention; however, while AST level still was significantly higher in the control (29.87±5.41 IU/l) than intervention (21.63±6.87 IU/l, P<0.0001), ALT level was not significantly different between the two groups (32.72±5.59 IU/l and 32.01±7.89 IU/l respectively, P=0.5). Conclusion: UDCA can be an effective drug to manage VPA-induced fluctuations of hepatic enzymes in children with recurrent epileptic seizures.

Drug Therapies for Chronic Cholestatic Liver Diseases

Though ursodeoxycholic acid (UDCA) remains the baseline treatment for most cholestatic liver diseases, UDCA treatment leaves approximately one-third of patients with primary biliary cholangitis (PBC) and all patients with primary sclerosing cholangitis (PSC) at risk for disease progression. New anticholestatic agents, including nuclear receptor agonists, choleretics, and bile acid synthesis suppressors, will likely increase response rates to therapy in PBC and PSC. Strategies that target early immune-mediated injury have so far been disappointing, hampered by the lack of biomarkers to detect early disease states, which then could profit from immunomodulatory therapy. Future concepts need to personalize treatments according to disease stage, progression, and phase, and to combine multiple drugs to target different pathogenic pathways.

Emerging therapies in primary sclerosing cholangitis: pathophysiological basis and clinical opportunities

Primary sclerosing cholangitis (PSC) is a progressive liver disease, histologically characterized by inflammation and fibrosis of the bile ducts, and clinically leading to multi-focal biliary strictures and with time cirrhosis and liver failure. Patients bear a significant risk of cholangiocarcinoma and colorectal cancer, and frequently have concomitant inflammatory bowel disease and autoimmune disease manifestations. To date, no medical therapy has proven significant impact on clinical outcomes and most patients ultimately need liver transplantation. Several treatment strategies have failed in the past and whilst prescription of ursodeoxycholic acid (UDCA) prevails, controversy regarding benefits remains. Lack of statistical power, slow and variable disease progression, lack of surrogate biomarkers for disease severity and other challenges in trial design serve as critical obstacles in the development of effective therapy. Advances in our understanding of PSC pathogenesis and biliary physiology over recent years has however led to a surge of clinical trials targeting various mechanistic compartments and currently raising hopes for imminent changes in patient management. Here, in light of pathophysiology, we outline and critically evaluate emerging treatment strategies in PSC, as tested in recent or ongoing phase II and III trials, stratified per a triad of targets of nuclear and membrane receptors regulating bile acid metabolism, immune modulators, and effects on the gut microbiome. Furthermore, we revisit the UDCA trials of the past and critically discuss relevant aspects of clinical trial design, including how the choice of endpoints, alkaline phosphatase in particular, may affect the future path to novel, effective PSC therapeutics.

Primary Biliary Cholangitis and Primary Sclerosing Cholangitis

Cholestatic liver diseases encompass a broad spectrum of pathologies, with the core injury occurring at the level of cholangiocytes and progressing to hepatic fibrosis and liver dysfunction. Primary biliary cholangitis and primary sclerosing cholangitis are the most significant progressive cholangiopathies in adults. Although rare, they commonly evolve to liver failure and need for liver transplantation. Despite recent advances in the basic knowledge of these cholangiopathies, the pathogenesis is still elusive. Targeted treatments to prevent disease progression and to preclude malignancy are not yet available. This review will address the general clinical features of both diseases, analyze their commonalities and differences, and provide a state-of-the art overview of the currently available therapeutics.

Review of pharmacotherapeutic treatments for primary sclerosing cholangitis

BACKGROUND

The objective of this review was to evaluate pharmacotherapeutic treatments for primary sclerosing cholangitis (PSC) through a literature search of current published data. A review of the current clinical data for each treatment is discussed.

METHODS

We conducted a systematic literature search for articles using EMBASE (1980 to April 1, 2018), and MEDLINE (1948 to April 1, 2018) using Ovid, to identify studies investigating various therapies in PSC. Search terms included the following: primary sclerosing cholangitis, cholangitis, sclerosing cholangitis; ursodeoxycholic acid, glucocorticoids, cyclosporine, tacrolimus, methotrexate, azathioprine, 6-mercaptopurine, penicillamine, anti-TNF, antibiotics, and probiotics. We also performed a review of current clinical trials using ClinicalTrials.gov. We considered for review relevant studies published in English, pilot studies, and randomized controlled trials involving human subjects.

RESULTS

Therapies that have been investigated in the management of PSC include those used in search terms and others that were not included in our search parameters. Analysis of published data involving each therapy was explored and none have shown any sustained, significant benefit in the treatment of PSC. In terms of relevance to patient care and clinical practice, this review evaluates and compares various pharmacotherapeutic treatments for PSC where liver transplantation remains the only definitive treatment.

CONCLUSIONS

To date, no clinical study of any drug has demonstrated effectiveness in terms of survival benefit or a decreased need for liver transplantation. More clinical studies are needed, and patients need to be adequately informed before any medical therapy for PSC is undertaken.

Treatment of primary sclerosing cholangitis in children

Primary sclerosing cholangitis (PSC) is a rare disease of stricturing and destruction of the biliary tree with a complex genetic and environmental etiology. Most patients have co-occurring inflammatory bowel disease. Children generally present with uncomplicated disease, but undergo a variable progression to end-stage liver disease. Within ten years of diagnosis, 50% of children will develop clinical complications including 30% requiring liver transplantation. Cholangiocarcinoma is a rare but serious complication affecting 1% of children. Ursodeoxycholic acid and oral vancomycin therapy used widely in children as medical therapy, and may be effective in a subset of patients. Gamma glutamyltransferase is a potential surrogate endpoint for disease activity, with improved survival in patients who achieve a normal value. Endoscopic retrograde cholangiopancreatography is a necessary adjunct to medical therapy to evaluate mass lesions or dominant strictures for malignancy, and also to relieve biliary obstruction. Liver transplantation remains the only option for patients who progress to end-stage liver disease. We review special considerations for patients before and after transplant, and in patients with inflammatory bowel disease. There is presently no published treatment algorithm or guideline for the management of children with PSC. We review the evidence for drug efficacy, dosing, duration of therapy, and treatment targets in PSC, and provide a framework for endoscopic and medical management of this complex problem.

Altered Expression of Retinol Metabolism-Related Genes in an ANIT-Induced Cholestasis Rat Model

Cholestasis is defined as a reduction of bile secretion caused by a dysfunction of bile formation. Insufficient bile secretion into the intestine undermines the formation of micelles, which may result in the reduced absorption of lipids and fat-soluble vitamins. Here, we investigated the retinol homeostasis and the alterations of retinol metabolism-related genes, including β-carotene 15,15′ monooxygenase (BCMO), lecithin:retinol acyltransferase (LRAT), aldehyde dehydrogenase (ALDH), cytochrome P450 26A1 (CYP26A1), and retinoic acid receptors (RAR) β, in a α-naphthyl isothiocyanate (ANIT)-induced cholestasis rat model. Moreover, we examined the expression of the farnesoid X receptor (FXR) target genes. Our results showed that plasma retinol levels were decreased in ANIT rats compared to control rats. On the contrary, hepatic retinol levels were not different between the two groups. The expression of FXR target genes in the liver and intestine of cholestasis model rats was repressed. The BCMO expression was decreased in the liver and increased in the intestine of ANIT rats compared to control rats. Finally, the hepatic expression of LRAT, RARβ, and ALDH1A1 in cholestatic rats was decreased compared to the control rats, while the CYP26A1 expression of the liver was not altered. The increased expression of intestinal BCMO in cholestasis model rats might compensate for decreased circulatory retinol levels. The BCMO expression might be regulated in a tissue-specific manner to maintain the homeostasis of retinol.

Novel and emerging therapies for cholestatic liver diseases

While bile acids are important for both digestion and signalling, hydrophobic bile acids can be harmful, especially when in high concentrations. Mechanisms for the protection of cholangiocytes against bile acid cytotoxicity include negative feedback loops via farnesoid X nuclear receptor (FXR) activation, the bicarbonate umbrella, cholehepatic shunting and anti-inflammatory signalling, among others. By altering or overwhelming these defence mechanisms, cholestatic diseases such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) can further progress to biliary cirrhosis, end-stage liver disease and death or liver transplantation. While PBC is currently treated with ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), many fail treatment, and we have yet to find an effective therapy for PSC. Novel therapies under evaluation target nuclear and surface receptors including FXR, transmembrane G-protein-coupled receptor 5 (TGR5), peroxisome proliferator-activated receptor (PPAR) and pregnane X receptor (PXR). Modulation of these receptors leads to altered bile composition, decreased cytotoxicity, decreased inflammation and improved metabolism. This review summarizes our current understanding of the role of bile acids in the pathophysiology of cholestatic liver diseases, presents the rationale for already approved medical therapies and discusses novel pharmacologic therapies under investigation.

Cholestatic liver diseases: new targets, new therapies

Cholestatic liver diseases result from gradual destruction of bile ducts, accumulation of bile acids and self-perpetuation of the inflammatory process leading to damage to cholangiocytes and hepatocytes. If left untreated, cholestasis will lead to fibrosis, biliary cirrhosis, and ultimately end-stage liver disease. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the two most common chronic cholestatic liver diseases affecting adults, and their etiologies remain puzzling. While treatment with ursodeoxycholic acid (UDCA) has significantly improved outcomes and prolonged transplant-free survival for patients with PBC, treatment options for UDCA nonresponders remain limited. Furthermore, there is no available medical therapy for PSC. With recent advances in molecular biochemistry specifically related to bile acid regulation and understanding of immunologic pathways, novel pharmacologic treatments have emerged. In this review, we discuss the standard of care and emphasize the various emerging treatments for PBC and PSC.

9-cis-retinoic acid elevates MRP3 expression by inhibiting sumoylation of RXRα to alleviate cholestatic liver injury

AIMS

Vitamin A and its metabolites has been found to be protective against cholestatic liver injury, but the exact underlying mechanisms involved in cholestatic liver injury remain unclear. The objective of this study was to determine the function and mechanisms of 9-cis-retinoic acid, the metabolite of vitamin A, in cholestatic liver injury.

METHODS

The bile duct ligated (BDL) mice were treated with 9-cis-retinoic acid by intravenous injection through the tail for 10 days. The liver function and histology were assessed in the matched group and experimental group. The expression of MRP3 in liver tissue was tested by qRT-PCR, Western blotting, and IHC. Effect of RXRα sumoylation on MRP3 expression was investigated at a cellular level. Influence of 9-cis-retinoic acid on RXRα sumoylation was also tested in cells.

RESULTS

Our findings showed that 9-cis-retinoic acid significantly decreases the serum ALT and AST level, alleviates hepatic necrosis of the BDL-mice. We also identified MRP3, an important protective hepatobiliary transporter in cholestasis, was elevated by 9-cis-retinoic acid in vivo and in vitro. 9-cis-retinoic acid weakened the sumoylation of RXRα, which promotes the cytoplasmic location of RXRα and lightens the interaction of RXRα and RARα. Inhibition of RXRα and RARα interaction increased MRP3 expression.

CONCLUSIONS

9-cis-retinoic acid alleviates cholestatic liver injury by elevating MRP3 expression through its mechanism of inhibiting sumoylation of RXRα.

Update in the Care and Management of Patients with Primary Sclerosing Cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis (PSC) is a progressive cholestatic liver disease for which specific medical therapy is not available. The goals of treatment are primarily early detection and management of complications. In this review, we discuss novel therapies under evaluation and provide the foundation for surveillance strategies.

RECENT FINDINGS

Drugs under investigation include norursodeoxycholic acid, nuclear receptor agonists, anti-fibrotics, antibiotics, and anti-inflammatory drugs. Endoscopic therapy is indicated for symptomatic dominant strictures and in the work-up of malignancies. Recently, the use of stents was associated with an increased rate of complications compared to balloon dilatation; and long-term stenting should be avoided. Malignancies currently account for most of the PSC-related mortality. Many drugs are emerging for the treatment of PSC but liver transplantation is the only treatment modality shown to prolong survival. PSC recurrence occurs in up to 35% of transplanted allografts within a median of 5 years. Surveillance for hepatobiliary and colorectal malignancies is indicated.

Cenicriviroc, a cytokine receptor antagonist, potentiates all-trans retinoic acid in reducing liver injury in cholestatic rodents

BACKGROUND & AIMS

Cholestatic liver injury is mediated by bile acid-induced inflammatory responses. We hypothesized that superior therapeutic effects might be achieved by combining treatments that reduce the bile acid pool size with one that blocks inflammation.

METHODS

Bile duct-ligated (BDL) rats and Mdr2(Abcb4)-/- mice were treated with all-trans retinoic acid (atRA), a potent inhibitor of bile acid synthesis, 5 mg/kg/d by gavage, or Cenicriviroc (CVC), a known antagonist of CCR2 and CCR5, 50 mg/kg/d alone or in combination for 14 days and 1 month respectively.

RESULTS

All-trans retinoic acid alone reduced bile acid pool size and liver necrosis in BDL rats. However, the combination with CVC further reduced liver to body weight ratio, bile acid pool size, plasma liver enzyme, bilirubin, liver necrosis and fibrosis when compared to the atRA treatment. The assessment of hepatic hydroxyproline content further confirmed the reduced liver injury concurrent with reduction of pro-inflammatory cytokines emphasizing the synergistic effects of these two agents. Profiling of hepatic inflammatory cells revealed that combination therapy reduced neutrophils and T cells but not macrophages. The superior therapeutic effects of combination treatment were also confirmed in Mdr2-/- mice where a significant reduction in plasma liver enzymes, bilirubin, liver fibrosis, bile duct proliferation and hepatic infiltration of neutrophils and T cells and expression of cytokines were found.

CONCLUSIONS

Multitargeted therapy is an important paradigm for treating cholestatic liver injury. The combination of CVC with atRA or other FXR activators may warrant a clinical trial in patients with cholestatic liver disease.

Primary Sclerosing Cholangitis, Part 1: Epidemiology, Etiopathogenesis, Clinical Features, and Treatment

Primary sclerosing cholangitis (PSC) is a chronic, idiopathic cholangiopathy that can progress to cirrhosis, end-stage liver disease, hepatobiliary cancer, and/or colorectal cancer. The course of PSC is often complicated by portal hypertension, symptoms of cholestasis, and recurrent bacterial cholangitis, among other conditions, with a consequent decrease in survival (median, approximately 20 years) and quality of life. The etiopathogenesis of PSC remains poorly understood, and, as such, pharmacotherapy has yet to be definitively established. Despite its rarity, PSC is the fifth leading indication for liver transplantation (LT) in the United States. Although the only intervention known to extend survival of patients with PSC, LT is costly and invasive, and recurrent PSC affects approximately 30% of LT recipients. Over the past several years, owing in part to progress in the understanding of PSC, novel pharmacotherapeutics have been developed, some of which are currently in the PSC clinical trial pipeline. Here, in the first of a 2-part series, we provide a review and update of the epidemiology, etiopathogenesis, clinical features, and treatment of PSC. The second part of the series will focus on cancer risk, prevention, and surveillance of PSC.

Vitamin A deficiency in chronic cholestatic liver disease: Is vitamin A therapy beneficial?

Chronic cholestatic diseases are progressive diseases of the biliary tract that cause hepatic fibrosis and ultimately lead to liver failure. Liver transplantation is the sole curative option currently available, and because of high morbidity and mortality rates of these diseases, new therapeutic approaches are needed. Vitamin A is a nutrient essential for health as it regulates many processes, including epithelial growth and immunological processes. Vitamin A is primarily stored in hepatic stellate cells, and during liver injury, through an unknown mechanism, these cells lose vitamin A and convert into collagen-producing myofibroblasts, which contributes to hepatic fibrosis. Vitamin A deficiencies in chronic cholestatic diseases have been frequently reported, and therefore, retinoid metabolism has attracted a lot of attention. Retinoids have been shown to attenuate or even prevent hepatic fibrosis, and to regulate hepatic immunological response to cholestatic injury in different rodent models of chronic cholestasis. Recently, their potential as therapeutic drugs in primary sclerosing cholangitis patients was analyzed. The aim of this review is to summarize the existing knowledge and hypotheses about vitamin A role and the disease progression in cholestatic liver disease.

Emerging treatments for primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic, cholestatic, idiopathic liver disease that can progress to end-stage liver disease, cirrhosis and cholangiocarcinoma. PSC is an uncommon and highly heterogeneous disease, associated with inflammatory bowel disease and a complex pathophysiology. To date, no medical therapies have proved effective. The only available treatment for end-stage PSC is liver transplant, but recurrence is a significant complication. Areas covered: This review will explore previously tested treatments, discuss current treatment strategies and present viewpoints about future emerging therapies in PSC. We searched PubMed using the noted keywords. We included data from full-text articles published in English. Further relevant articles were identified from the reference lists of review articles. Expert commentary: The development of new therapies in PSC has been challenging. However, with greater awareness of the disease nowadays, new insights into the disease may help in the design of future therapeutic agents in PSC and ultimately in effective therapies.