Effects of long-term rifampicin administration in primary biliary cirrhosis

Sodium/bile acid co-transporter inhibitors currently in preclinical or early clinical development for the treatment of primary biliary cholangitis

INTRODUCTION

Pruritus is common and often undertreated in patients with primary biliary cholangitis (PBC). Existing treatments largely have an aging and low-quality evidence base, and studies included only small numbers of patients. More recent data that has added to our understanding of pruritus treatments has often come from clinical trials where itching was a secondary outcome measure in a trial designed primarily to assess disease-modifying agents. This area represents an unmet clinical need in the management of PBC.

AREAS COVERED

In this manuscript, we first summarize the proposed mechanisms for PBC-related pruritus and the current treatment paradigm. We then present an appraisal of the existing pre-clinical and clinical evidence for the use of ileal bile acid transporter inhibitors (IBATis) for this indication in PBC patients.

EXPERT OPINION

Evidence for the efficacy of IBATis is promising but limited by the currently available volume of data. Furthermore, larger clinical trials with long-term data on efficacy, safety and tolerability are needed to confirm the role of using IBATis in clinical practice and their place on the itch treatment ladder. Additional focus should also be given to exploring the disease-modifying potential of IBATis in PBC.

Primary biliary cholangitis: Epidemiology, prognosis, and treatment

Primary biliary cholangitis (PBC) is a chronic cholestatic autoimmune liver disease characterized by a destructive, small duct, and lymphocytic cholangitis, and marked by the presence of antimitochondrial antibodies. The incidence and prevalence of PBC vary widely in different regions and time periods, and although disproportionally more common among White non-Hispanic females, contemporary data show a higher prevalence in males and racial minorities than previously described. Outcomes largely depend on early recognition of the disease and prompt institution of treatment, which, in turn, are directly influenced by provider bias and socioeconomic factors. Ursodeoxycholic acid remains the initial treatment of choice for PBC, with obeticholic acid and fibrates (off-label therapy) reserved as add-on therapy for the management of inadequate responders or those with ursodeoxycholic acid intolerance. Novel and repurposed drugs are currently at different stages of clinical development not only for the treatment of PBC but also for its symptomatic management. Here, we summarize the most up-to-date data regarding the epidemiology, prognosis, and treatment of PBC, providing clinically useful information for its holistic management.

Systematic review: efficacy of therapies for cholestatic pruritus

Background

Pruritus is a symptom of several cholestatic liver diseases (CLDs) that can impair health-related quality of life (HRQoL). Despite evidence-based guideline therapy, managing cholestatic pruritus (CP) remains challenging, thus making the need for newer, more effective therapeutic agents more evident.

Objective

Our study evaluated the efficacy of existing CP therapies.

Design

Systematic review.

Data sources

From inception until March 2023, we conducted a comprehensive search of MEDLINE, Cochrane, EMBASE, Scopus, ClinicalTrial.gov, and other sources, including pharmaceutical webpages and conference proceedings published in English that reported on CP interventions.

Methods

Two reviewers independently conducted screening and full-text review of articles with extraction conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The methodological quality of studies included in our qualitative synthesis was assessed by using the Cochrane ROBINS-I and ROBINS-II tools for interventional studies and the National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. The primary outcome assessed in our systematic review was the severity of CP after therapy.

Results

Of 3293 screened articles, 92 studies were eligible for inclusion in the qualitative synthesis. Some patients' HRQoL improved with evidence-based standard therapy. Others, particularly those with severe and refractory CP, often required conversion to or addition of experimental noninvasive (e.g., ondansetron) or extracorporeal liver support to alleviate CP. In addition, studies investigating a newer class drug, the ileal bile acid transporter inhibitor (IBATi), demonstrate its effectiveness in reducing serum bile acid and alleviating CP with sustained improvement noted in patients with the inherited childhood cholestatic disorders - progressive familial intrahepatic cholestasis and Alagille syndrome.

Conclusion

Our findings consolidate data on the efficacy of guideline-based approaches and newer therapies for CP. While the initial findings are promising, additional clinical trials will be needed to determine the full extent of IBATi's efficacy and potential use in treating other common CLDs. These results provide a foundation for future research and highlight the need for continued investigation into the management and treatment of CLDs.

Uncovering key molecules and immune landscape in cholestatic liver injury: implications for pathogenesis and drug therapy

Background: Cholestasis is a common pathological process in a variety of liver diseases that may lead to liver fibrosis, cirrhosis, and even liver failure. Cholestasis relief has been regarded as a principal target in the management of multiple chronic cholestasis liver diseases like primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) at present. However, complicated pathogenesis and limited acknowledgments fettered therapeutic development. Therefore, this study aimed to systematically analyze miRNA-mRNA regulatory networks in cholestatic liver injury in order to provide new treatment strategies. Methods: Gene Expression Omnibus (GEO) database (GSE159676) was used to screen differentially expressed hepatic miRNAs and mRNAs in the PSC vs. control comparison and the PBC vs. control comparison, respectively. MiRWalk 2.0 tool was used to predict miRNA-mRNA pairs. Subsequently, functional analysis and immune cell infiltration analysis were performed to explore the pivotal functions of the target genes. RT-PCR was used to verify the result. Results: In total, a miRNA-mRNA network including 6 miRNAs (miR-122, miR-30e, let-7c, miR-107, miR-503, and miR-192) and 8 hub genes (PTPRC, TYROBP, LCP2, RAC2, SYK, TLR2, CD53, and LAPTM5) was constructed in cholestasis. Functional analysis revealed that these genes were mainly involved in the regulation of the immune system. Further analysis revealed that resting memory CD4 T cells and monocytes could potentially participate in cholestatic liver injury. The expressions of DEMis and eight hub genes were verified in ANIT-induced and BDL-induced cholestatic mouse models. Furthermore, SYK was found to have an impact on the response to UDCA, and its mechanism was possibly associated with complement activation and monocyte reduction. Conclusion: In the present study, a miRNA-mRNA regulatory network was constructed in cholestatic liver injury, which mostly mediated immune-related pathways. Moreover, the targeted gene SYK and monocytes were found to be related to UDCA response in PBC.

Cholestatic Pruritus Treatments in Primary Biliary Cholangitis and Primary Sclerosing Cholangitis: A Systematic Literature Review

BACKGROUND AND AIMS

We conducted a systematic literature review to understand the evidence supporting treatment decisions for cholestatic pruritus associated with primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC).

METHODS

Studies that enrolled ≥ 75% participants with PBC or PSC and reported ≥ 1 endpoint(s) related to efficacy, safety, health-related quality of life (HRQoL) or other patient-reported outcomes were included. Bias was assessed using the Cochrane risk of bias tool for randomised controlled trials (RCTs) and the Quality of Cohort studies tool for non-RCTs.

RESULTS

Thirty-nine publications were identified, covering 42 studies and six treatment classes (including investigational and approved products): anion-exchange resins, antibiotics (rifampicin/derivatives), opiates, selective serotonin reuptake inhibitors, fibrates, ileal bile acid transporter inhibitors and other agents not categorised in these six classes. Across studies, median sample size was small (n = 18), 20 studies were over 20 years old, 25 followed patients for ≤ 6 weeks, only 25 were RCTs. Pruritus was assessed using several different tools, with inconsistencies in their application. Cholestyramine, considered first-line therapy for moderate-severe cholestatic pruritus, was assessed in six studies (two RCTs) including 56 patients with PBC and 2 with PSC, with evidence of efficacy demonstrated in only three studies, among which, two RCTs were assessed as having a high risk of bias. Findings were similar for other drug classes.

CONCLUSIONS

There is a lack of consistent and reproducible evidence available on efficacy, impact on HRQoL, and safety of cholestatic pruritus treatments, leaving physicians to rely on clinical experience rather than evidence-based medicine for treatment selection.

Pathogenesis and Treatment of Pruritus Associated with Chronic Kidney Disease and Cholestasis

Itching is an unpleasant sensation that provokes the desire to scratch. In general, itching is caused by dermatologic diseases, but it can also be caused by systemic diseases. Since itching hampers patients' quality of life, it is important to understand the appropriate treatment and pathophysiology of pruritus caused by systemic diseases to improve the quality of life. Mechanisms are being studied through animal or human studies, and various treatments are being tested through clinical trials. We report current trends of two major systemic diseases: chronic kidney disease and cholestatic liver disease. This review summarizes the causes and pathophysiology of systemic diseases with pruritus and appropriate treatments. This article will contribute to patients' quality of life. Further research will help understand the mechanisms and develop new strategies in the future.

Evaluation and Management of Pruritus in Primary Biliary Cholangitis

Chronic pruritus is a classic symptom in patients with primary biliary cholangitis. It affects up to two-thirds of patients in the course of the disease. Efficient therapy consists of topical treatment combined with systemic options such as anion exchangers, rifampicin, bezafibrate, μ-opioid receptor antagonists, selective-serotonin receptor uptake inhibitors, and gabapentinoids. Future therapeutic approaches may contain the selective blockade of the enterohepatic cycle by inhibiting the ileal bile acid transporter, the agonism at κ-opioid receptors, and antagonism of the mas-related G protein-coupled receptor X4. As nondrug treatment, ultraviolet B therapy, albumin dialysis, and biliary drainage are available at specialized centers.

Immunologic Responses and the Pathophysiology of Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune liver disease with a female predisposition and selective destruction of intrahepatic small bile ducts leading to nonsuppurative destructive cholangitis. It is characterized by seropositivity of antimitochondrial antibodies or PBC-specific antinuclear antibodies, progressive cholestasis, and typical liver histologic manifestations. Destruction of the protective bicarbonate-rich umbrella is attributed to the decreased expression of membrane transporters in biliary epithelial cells (BECs), leading to the accumulation of hydrophobic bile acids and sensitizing BECs to apoptosis. A recent X-wide association study reveals a novel risk locus on the X chromosome, which reiterates the importance of Treg cells.

Artificial liver support in patients with liver failure: a modified DELPHI consensus of international experts

The present narrative review on albumin dialysis provides evidence-based and expert opinion guidelines for clinicians caring for adult patients with different types of liver failure. The review was prepared by an expert panel of 13 members with liver and ntensive care expertise in extracorporeal liver support therapies for the management of patients with liver failure. The coordinating committee developed the questions according to their importance in the management of patients with liver failure. For each indication, experts conducted a comprehensive review of the literature aiming to identify the best available evidence and assessed the quality of evidence based on the literature and their experience. Summary statements and expert's recommendations covered all indications of albumin dialysis therapy in patients with liver failure, timing and intensity of treatment, efficacy, technical issues related to the device and safety. The panel supports the data from the literature that albumin dialysis showed a beneficial effect on hepatic encephalopathy, refractory pruritus, renal function, reduction of cholestasis and jaundice. However, the trials lacked to show a clear beneficial effect on overall survival. A short-term survival benefit at 15 and 21 days respectively in acute and acute-on-chronic liver failure has been reported in recent studies. The technique should be limited to patients with a transplant project, to centers experienced in the management of advanced liver disease. The use of extracorporeal albumin dialysis could be beneficial in selected patients with advanced liver diseases listed for transplant or with a transplant project. Waiting future large randomized controlled trials, this panel experts' statements may help careful patient selection and better treatment modalities.

Nuclear Receptor Pathways Mediating the Development of Boar Taint

The nuclear receptors PXR, CAR, and FXR are activated by various ligands and function as transcription factors to control the expression of genes that regulate the synthesis and metabolism of androstenone and skatole. These compounds are produced in entire male pigs and accumulate in the fat to cause the development of a meat quality issue known as boar taint. The extent of this accumulation is influenced by the synthesis and hepatic clearance of androstenone and skatole. For this reason, PXR, CAR, and FXR-mediated signaling pathways have garnered interest as potential targets for specialized treatments designed to reduce the development of boar taint. Recent research has also identified several metabolites produced by gut microbes that act as ligands for these nuclear receptors (e.g., tryptophan metabolites, short-chain fatty acids, bile acids); however, the connection between the gut microbiome and boar taint development is not clear. In this review, we describe the nuclear receptor signaling pathways that regulate the synthesis and metabolism of boar taint compounds and outline the genes involved. We also discuss several microbial-derived metabolites and dietary additives that are known or suspected nuclear receptor ligands and suggest how these compounds could be used to develop novel treatments for boar taint.

PXR as the tipping point between innate immune response, microbial infections, and drug metabolism

Pregnane X receptor (PXR) is a xenosensor that acts as a transcription factor in the cell nucleus to protect cells from toxic insults. In response to exposure to several chemical agents, PXR induces the expression of enzymes and drug transporters that biotransform xenobiotic and endobiotic and eliminate metabolites. Recently, PXR has been shown to have immunomodulatory effects that involve cross-communication with molecular pathways in innate immunity cells. Conversely, several inflammatory factors regulate PXR signaling. This review examines the crosstalk between PXR and nuclear factor kappa B (NFkB), Toll-like receptors (TLRs), and inflammasome components. Discussions of the consequences of these interactions on immune responses to infections caused by viruses, bacteria, fungi, and parasites are included together with a review of the effects of microorganisms on PXR-associated drug metabolism. This paper aims to encourage researchers to pursue studies that will better elucidate the relationship between PXR and the immune system and thus inform treatment development.

Efficacy of Treatments for Cholestatic Pruritus: A Systemic Review and Meta-analysis

Cholestatic itch is a disabling symptom that may be secondary to liver or biliary diseases. Management of cholestatic pruritus is complex. A systematic review and meta-analysis on the efficacy of treatments for cholestatic pruritus were performed. PubMed and Cochrane Library were searched using the algorithm “(hepatitis OR cholestatic OR liver) AND (pruritus OR itch) AND (management OR treatment OR treatments)” for 1975–2019. Of the 2,264 articles identified, 93 were included in a systematic review and 15 in a meta-analysis (studies evaluating pruritus with a visual analogue scale). Some treatments act by reducing levels of pruritogens in the enterohepatic cycle, others modify the metabolism or secretion of these pruritogens, or act on pruritus pathways. A further possible treatment is albumin dialysis. However, due to many heterogeneities in the reviewed studies it is difficult to identify and recommend an optimum treatment. Only 15 studies were included in the meta-analysis, due to the small number of randomized studies using a visual analogue scale.

Risk assessment of micafungin-induced liver injury using spontaneous reporting system data and electronic medical records

INTRODUCTION

There is limited information regarding antifungal-induced liver injuries, which have high mortality rates. Therefore, we used the Japanese Adverse Drug Event Report (JADER) database for signal detection associated with antifungal-induced liver injuries and medical records for risk assessment.

METHODS

Reports of antifungal-induced liver injuries from JADER data were analyzed to calculate the reporting odds ratio (ROR) and 95% confidence interval (CI). A medical record-based study involving 109 adult patients treated with micafungin shows liver injury as the primary outcome in patients treated with micafungin. The albumin-bilirubin (ALBI) score was calculated based on albumin and total bilirubin levels. We selected five explanatory factors for multivariable logistic regression: alanine aminotransferase ≥20 IU/L, alkaline phosphatase ≥372 IU/L, aspartate aminotransferase ≥25 IU/L, ALBI score ≥ -1.290, and age ≥65 years.

RESULTS

Signal detection for micafungin was observed in both, hepatocellular and cholestatic injuries, as per data from JADER. Univariate analyses performed on medical records suggest that alanine aminotransferase (p = 0.008), aspartate aminotransferase (p = 0.036), alkaline phosphatase (p = 0.045), and ALBI score (p = 0.028) may be factors associated with micafungin-induced liver injury. Based on multivariable logistic regression, the adjusted odds ratio for micafungin-induced liver injury in patients with ALBI score ≥ -1.290 was 2.78 (95% CI: 1.014-7.605, p = 0.047), suggesting that low hepatic functional reserve could be a risk factor for micafungin-induced liver injury.

CONCLUSIONS

Careful monitoring of liver function may be necessary for micafungin administration in patients with low hepatic functional reserve.

The effects of alcohol and illicit drug use on the skin

Early identification of cutaneous manifestations of alcohol and illicit drug use can aid in the diagnosis and management of these uses, as well as their sequelae. In addition, the effects of alcohol and illicit drug use on the skin can result in significant morbidity. Alcohol misuse can present with jaundice, pruritus, pigmentary alterations, urticaria, hair and nail changes, and oral changes. It is also a risk factor for skin cancer and infections. Vascular disturbances associated with alcohol misuse include telangiectasias, palmar erythema, caput medusae, and flushing. Diseases related to alcohol misuse include nutritional deficiencies, porphyria cutanea tarda, psoriasis, seborrheic dermatitis, nummular dermatitis, and rosacea. Other conditions seen in alcohol misuse include Dupuytren contracture, Peyronie disease, and pancreatitis. Dermatologists should also be aware of hepatotoxic medications that are commonly prescribed for skin diseases so as to avoid initiating hepatoxicity in patients who use alcohol. Illicit drug use can manifest with cutaneous fibrosis, scarring, granulomas, ulceration, pruritus, infections, cocaine-levamisole-induced vasculitis, tooth decay, and oral disease. By recognizing the cutaneous stigmata of alcohol and illicit drug use, dermatologists can aid in the identification and treatment of patients suffering from these addictions.

Use of Butorphanol as Treatment for Cholestatic Itch

BACKGROUND

Pruritus is a debilitating symptom of cholestatic diseases such as primary biliary cholangitis and primary sclerosing cholangitis and often results in major reduction in quality of life for afflicted patients. Classic treatment options for the treatment of cholestatic pruritus include antihistamines, bile acid resins, serotonin reuptake inhibitors, and mu-opioid antagonists. Unfortunately, these drugs are not always successful in treating pruritus of cholestasis and may be associated with adverse effects. Recent advances in our understanding of itch pathophysiology have led to the use of butorphanol, a kappa-opioid agonist and mu-opioid antagonist, for the treatment of various forms of pruritus. Reports of butorphanol to treat cholestatic itch specifically are rare.

AIMS

To better understand the role of butorphanol in the treatment of cholestatic pruritus, including characterization of its side effect profile.

METHODS

We present a case series of eight adult patients with cholestatic disease who were treated with butorphanol in hopes of alleviating intractable pruritus. Patients were identified through a clinical data request form serviced by University of Miami Information Technology.

RESULTS

Five out of eight patients (62.5%) reported successful reductions in itch severity after treatment with butorphanol, two patients reported no (or transient) change in itch severity, and one patient reported a paradoxical increase in itching. Side effects included somnolence, sedation, nausea, vomiting, and dizziness.

CONCLUSIONS

Butorphanol was safe and leads to clinically significant symptomatic improvement. Clinicians should be aware of butorphanol as an off-label treatment option for pruritus of cholestasis. Further studies are needed to better characterize the effect of butorphanol on cholestatic itch.

Safety considerations for the management of cholestatic itch

Introduction: Pruritus is adisabling symptom common to cholestatic liver disorders. Its pathophysiology has not been completely elucidated and although multiple mediators have been identified, only lysophosphatidic acid (LPA) and its synthetizing enzyme autotaxin (ATX) appear to consistently correlate with symptom intensity. This review aims to summarize the most relevant safety and efficacy data regarding both standard and new medications utilized to treat pruritus in cholestatic liver disease.Areas covered: International societies like the AASLD and EASL recommend astepwise approach for the management of cholestatic itch. However, therapeutic response is variable. Cholestyramine is considered first-line, followed by rifampicin, naltrexone and sertraline. When used appropriately, these medications have afavorable adverse events profile with most side effects related to drug class and not to the underlying etiology of liver disease.Expert opinion: Although conventional therapies seem to be effective in aproportion of patients, asizable number of cases remain refractory and require the utilization of experimental treatments. Multiple potential targets, especially in the ATX-LPA axis have yet to be pharmacologically explored, with ongoing translational and clinical research. Novel drugs are currently being developed for the management of cholestatic itching with promising results and afavorable safety profile.

Endogenous Opioid Levels Do Not Correlate With Itch Intensity and Therapeutic Interventions in Hepatic Pruritus

Background: Chronic pruritus affects up to 70% of patients with immune-mediated hepatobiliary disorders. Antagonists of the μ-opioid receptor (MOR) and agonists of the κ-opioid receptor (KOR) are used to treat hepatic itch, albeit with limited success. An imbalance between ligands of MOR and KOR receptors has recently been suggested as a potential mechanism of hepatic pruritus. In this study, we therefore investigated systemic levels of important endogenous opioids such as β-endorphin, dynorphin A, Leu- and Met-enkephalin in plasma of a large cohort of well-characterized patients with immune-mediated cholestatic disorders, including patients with liver cirrhosis, and during effective anti-pruritic therapy.

Methods: Plasma samples and clinical data were prospectively collected from well-characterized patients with primary/secondary sclerosing cholangitis (PSC/SSC), primary biliary cholangitis (PBC) and overlap syndromes suffering from pruritus (n = 29) and age-, gender- and disease-matched controls without pruritus (n = 27) as well as healthy controls (n = 20). General laboratory testing for hepatobiliary and renal function was performed. Levels of β-endorphin, dynorphin A, Leu- and Met-enkephalin were quantified in plasma by ELISA. Intensity of pruritus over the last week was evaluated using a visual analog scale (VAS, 0–10).

Results: PBC and PSC patients with or without pruritus did neither differ in disease entity, disease stage, nor in the presence of cirrhosis. While both dynorphin A and β-endorphin concentrations were lower in pruritic patients compared to those without pruritus and healthy controls, the MOR/KOR ligand ratio was unaltered. No significant differences were observed for Leu- and Met-enkephalin concentrations. Opioid levels correlated with neither itch intensity nor stage of disease. Cirrhotic patients displayed higher concentrations of MOR agonist Leu-enkephalin and KOR agonist dynorphin A. Endogenous opioid levels remained largely unchanged after successful treatment with the potent anti-pruritic drugs rifampicin and bezafibrate.

Conclusions: Endogenous opioid levels and the MOR/KOR ligand ratio neither correlate with itch intensity nor differentiate pruritic from non-pruritic patients with immune-mediated liver diseases. Thus, endogenous opioids may modulate signaling pathways involved in hepatic pruritus, but are unlikely to represent the major pruritogens in liver disease.

Cholestatic liver disease: Practice guidelines from the Saudi Association for the Study of Liver diseases and Transplantation

Cholestatic liver diseases (CLDs) are a group of diseases characterized by jaundice and cholestasis as the main presentation with different complications, which have considerable impact on the liver and can lead to end-stage liver disease, cirrhosis, and liver-related complications. In the last few years, tremendous progress has been made in understanding the pathophysiology, diagnosis, and treatment of patients with these conditions. However, several aspects related to the management of CLDs remain deficient and unclear. Due to the lack of recommendations that can help in the management, treatment of those conditions, the Saudi Association for the Study of Liver diseases and Transplantation (SASLT) has created a task force group to develop guidelines related to CLDs management in order to provide a standard of care for patients in need. These guidelines provide general guidance for health care professionals to optimize medical care for patients with CLDs for both adult and pediatric populations, in association with clinical judgments to be considered on a case-by-case basis. These guidelines describe common CLDs in Saudi Arabia, with recommendations on the best approach for diagnosis and management of different diseases based on the Grading of Recommendation Assessment (GRADE), combined with a level of evidence available in the literature.

Cutaneous Manifestations of Chronic Liver Disease

Given the visibility of cutaneous findings, skin manifestations are often a presenting symptom of underlying systemic disease, including chronic liver disease. Many cutaneous signs and symptoms that correlate with chronic liver disease are common physical examination findings in patients with no history of liver disease. It is nonetheless important to be aware that these cutaneous findings may be an indication of underlying liver disease and often occur in the setting of such hepatic dysfunction. This article covers general cutaneous signs that may correlate with various liver diseases and describes specific cutaneous signs as they relate to more specific liver diseases.

Newer Approaches to the Management of Pruritus in Cholestatic Liver Disease

Purpose of Review

Chronic pruritus represents a burdensome symptom in cholestatic liver disease. This review recommends a stepwise therapeutic approach, alongside with providing information on epidemiology, pathophysiology, and novel drug targets.

Recent Findings

Current epidemiological data emphasize chronic itch as a major symptom in immune-mediated liver diseases such as primary biliary cholangitis affecting up to 70% of patients with a significant number suffering from long-lasting and severe pruritus. κ-opioid receptor (KOR) agonists, PPAR agonists, and ileal bile acid transporter (IBAT) inhibitors are currently investigated for their anti-pruritic efficacy in clinical trials. Future therapies may target the autotaxin-lysophosphatidic acid-axis or the Mas-related GPCR MRGPRX4.

Summary

Cholestatic pruritus still remains a challenging symptom for patients and physicians. Using a stepwise approach including cholestyramine, rifampicin, bezafibrate, naltrexone, and sertraline, pruritus is often adequately manageable. KOR agonists and IBAT inhibitors are currently the most promising anti-pruritic drugs for cholestatic pruritus in development.

Primary biliary cholangitis: pathogenesis and therapeutic opportunities

Primary biliary cholangitis is a chronic, seropositive and female-predominant inflammatory and cholestatic liver disease, which has a variable rate of progression towards biliary cirrhosis. Substantial progress has been made in patient risk stratification with the goal of personalized care, including early adoption of next-generation therapy with licensed use of obeticholic acid or off-label fibrate derivatives for those with insufficient benefit from ursodeoxycholic acid, the current first-line drug. The disease biology spans genetic risk, epigenetic changes, dysregulated mucosal immunity and altered biliary epithelial cell function, all of which interact and arise in the context of ill-defined environmental triggers. A current focus of research on nuclear receptor pathway modulation that specifically and potently improves biliary excretion, reduces inflammation and attenuates fibrosis is redefining therapy. Patients are benefiting from pharmacological agonists of farnesoid X receptor and peroxisome proliferator-activated receptors. Immunotherapy remains a challenge, with a lack of target definition, pleiotropic immune pathways and an interplay between hepatic immune responses and cholestasis, wherein bile acid-induced inflammation and fibrosis are dominant clinically. The management of patient symptoms, particularly pruritus, is a notable goal reflected in the development of rational therapy with apical sodium-dependent bile acid transporter inhibitors.

Consensus guidelines: best practices for detection, assessment and management of suspected acute drug-induced liver injury occurring during clinical trials in adults with chronic cholestatic liver disease

BACKGROUND

Improved knowledge of the molecular pathophysiology and immunopathogenesis of cholestatic liver diseases in recent years has led to an increased interest in developing novel therapies. Patients with cholestatic liver disease often require different approaches to assessment and management of suspected drug-induced liver injury (DILI) compared to those with healthy livers and those with parenchymal liver diseases. At present, there are no regulatory guidelines or society position papers, that systematically address best practices pertaining to detection of DILI in these patients.

AIMS

To outline best practices for detection, assessment and management of suspected acute DILI during clinical trials in adults with the cholestatic liver diseases - Primary Biliary Cholangitis (PBC) and Primary Sclerosing Cholangitis (PSC).

METHODS

This is one of the several papers developed by the IQ DILI Initiative, which is comprised of members from 16 pharmaceutical companies, in collaboration with DILI experts from academia and regulatory agencies. The contents are the result of an extensive literature review, as well as in-depth discussions among industry, regulatory and academic DILI experts, to achieve consensus recommendations on DILI-related issues occurring during clinical trials for cholestatic liver diseases.

RESULTS

Recommended best practices are outlined pertaining to hepatic eligibility criteria, monitoring of liver tests, approach to a suspected DILI signal, and hepatic discontinuation rules.

CONCLUSIONS

This paper provides a framework for the approach to detection, assessment and management of suspected acute DILI occurring during clinical trials in adults with cholestatic liver disease.

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.

Treatment of Pruritus Secondary to Liver Disease

PURPOSE OF REVIEW

Pruritus is a common extrahepatic symptom in various liver disorders, in particularly those with cholestatic features. This review summarizes epidemiology, pathophysiology, evidence-based therapeutic recommendations and currently investigated drugs for pruritus in hepatobiliary disorders.

RECENT FINDINGS

Recent epidemiological data suggest pruritus as a common and relevant symptom in immune-mediated liver diseases, i.e., primary biliary cholangitis (PBC) with over 70% affected patients, up to 56% suffering from chronic pruritus. The better pathophysiological understanding of hepatic pruritus has led to the identification of novel therapeutic targets, addressed in drug trials using KOR agonists, PPAR agonists, and ileal bile acid transporter inhibitors. Hepatic itch remains among the most agonizing symptoms for affected patients and a clinical challenge for physicians. Therapeutic recommendations include a guideline-based stepwise approach starting with cholestyramine, followed by rifampicin, naltrexone, and sertraline. Bezafibrate and ileal bile acid transporter inhibitors represent promising future anti-pruritic treatment options.

Cholestatic pruritus: Emerging mechanisms and therapeutics

Patients suffering from cholestasis often report experiencing a debilitating, unrelenting itch. In contrast to conditions, such as urticaria, in which histamine primarily drives itch (pruritus), cholestatic pruritus is multifactorial and more difficult to treat. Existing therapies are not always effective and have undesirable adverse effect profiles. Here, we conducted a systematic literature review to evaluate conventional treatment strategy, current pathophysiologic understanding, and the role of new therapies in the context of cholestatic pruritus. We discuss novel findings implicating bile acids, lysophosphatidic acid, and bilirubin as potential important mediators of cholestatic itch. New therapies that aim to remove or modulate pruritogens have been supported in observational cohort studies and randomized controlled trials. Although these new therapies show promise, further research is needed to confirm the pathophysiology of cholestatic pruritus so that targeted therapy can be developed.

Ursolic Acid, a Novel Liver X Receptor α (LXRα) Antagonist Inhibiting Ligand-Induced Nonalcoholic Fatty Liver and Drug-Induced Lipogenesis

Nonalcoholic fatty liver disease (NAFLD) is a very common liver disease, and its incidence has significantly increased worldwide. The liver X receptor α (LXRα) is a multifunctional nuclear receptor that controls lipid homeostasis. Inhibition of LXRα transactivation may be beneficial for NAFLD and hyperlipidemia treatment. Ursolic acid (UA) is a plant triterpenoid with many beneficial effects; however, the mechanism of its action on LXRα remains elusive. We evaluated the effects of UA on T0901317 (T090)-induced LXRα activation and steatosis. UA significantly decreased the LXR response element and sterol regulatory element-binding protein-1c ( SREBP-1c) gene promoter activities, mRNA, protein expression of LXRα target genes, and hepatic cellular lipid content in a T090-induced mouse model. A molecular docking study indicated that UA bound competitively with T090 at the LXRα ligand binding domain. UA stimulated AMP-activated protein kinase (AMPK) phosphorylation in hepatic cells and increased corepressor, small heterodimer partner-interacting leucine zipper protein (SMILE) but decreased coactivator, steroid receptor coactivator-1 (SRC-1) recruitment to the SREBP-1c promoter region. In contrast, UA induced SRC-1 binding but decreased SMILE binding to reverse cholesterol transport-related gene promoters in intestinal cells, increasing lipid excretion from intestinal cells. Additionally, UA reduced valproate-induced LXRα mediated and rifampin-induced pregnane X receptor mediated lipogenesis, offering potential treatments for drug-induced hepatic steatosis. Thus, UA displays liver specificity and can be selectively repressed while RCT stimulation by LXRα is preserved and enhanced. This is a novel therapeutic option to treat NAFLD and may be helpful in developing LXR agonists to prevent atherosclerosis.

Oleanolic Acid Inhibits Liver X Receptor Alpha and Pregnane X Receptor to Attenuate Ligand-Induced Lipogenesis

Liver X receptor α (LXRα) controls important biological and pathophysiological processes such as lipid homeostasis. Inhibiting LXRα transactivation may beneficial in the treatment of nonalcoholic fatty liver disease (NAFLD), which is one of the main causes of liver diseases and hyperlipidemia. Oleanolic acid (OA) is a naturally occurring triterpenoid found in many plants. It has several beneficial effects on biological pathways; however, the mechanisms underlying its effects on LXRα are unclear. Therefore, we evaluated the effects of OA on T0901317-induced LXRα activation and explored whether OA can attenuate hepatic lipogenesis. The results showed that OA significantly decreased the promoter activities of LXR response element and sterol regulatory element binding protein-1c (SREBP-1c). It also decreased the mRNA and protein expression of LXRα target genes. These resulted in reduced hepatocellular lipid content. Our results also revealed that the overall binding pose of OA is similar to the X-ray pose of T0901317. Furthermore, OA stimulated AMP-activated protein kinase phosphorylation in hepatic cells. Additionally, it increased small heterodimer partner-interacting leucine zipper protein (SMILE) but decreased steroid receptor coactivator-1 (SRC-1) recruitment to the SREBP-1c promoter region. OA also enhanced LXRα-mediated induction of reverse cholesterol transport (RCT)-related gene, ATP-binding cassette transporter (ABC) A1, and ABCG1 expression in intestinal cells. It was found that OA increased the binding of SRC-1 but decreased SMILE recruitment to the ABCG1 gene promoter region. Furthermore, it reduced valproate- and rifampin-induced LXRα- and pregnane X receptor-mediated lipogenesis, respectively, which indicates its potential benefit in treating drug-induced hepatic steatosis. The results also show that OA is liver-specific and can be selectively repressed of lipogenesis. Moreover, it preserves and enhances LXRα-induced RCT stimulation. The results show that OA may be a promising treatment for NAFLD. Additionally, it can be used in the development of LXRα agonists to prevent atherosclerosis.

Primary biliary cholangitis

Primary cholangitis (cirrhosis) is a chronic cholestatic disease with an unquestionable female predominance. It is characterised by inflammation of the small and medium size bile ducts, and can eventually progress to cirrhosis. Most patients remain asymptomatic and are diagnosed by the casual finding of an anicteric biochemical cholestasis with increased alkaline phosphatase. The pathogenesis is unknown and of presumed autoimmune origin in genetic susceptible subjects. M2-type antimitochondrial antibodies, and specific antinuclear antibodies (gp210 and Sp100) are typical and specific of the disease. The positivity of these antibodies and a biochemical cholestasis are sufficient for diagnosis, without the need for liver biopsy. Ursodeoxycholic acid is the specific treatment with an excellent response in more than 60% of patients. When this optimal response is not observed, it can be combined with new agents, but those that have shown to be effective are those that improve cholestasis such as fibrates and obeticholic acid.

The British Society of Gastroenterology/UK-PBC primary biliary cholangitis treatment and management guidelines

Primary biliary cholangitis (formerly known as primary biliary cirrhosis, PBC) is an autoimmune liver disease in which a cycle of immune mediated biliary epithelial cell injury, cholestasis and progressive fibrosis can culminate over time in an end-stage biliary cirrhosis. Both genetic and environmental influences are presumed relevant to disease initiation. PBC is most prevalent in women and those over the age of 50, but a spectrum of disease is recognised in adult patients globally; male sex, younger age at onset (<45) and advanced disease at presentation are baseline predictors of poorer outcome. As the disease is increasingly diagnosed through the combination of cholestatic serum liver tests and the presence of antimitochondrial antibodies, most presenting patients are not cirrhotic and the term cholangitis is more accurate. Disease course is frequently accompanied by symptoms that can be burdensome for patients, and management of patients with PBC must address, in a life-long manner, both disease progression and symptom burden. Licensed therapies include ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), alongside experimental new and re-purposed agents. Disease management focuses on initiation of UDCA for all patients and risk stratification based on baseline and on-treatment factors, including in particular the response to treatment. Those intolerant of treatment with UDCA or those with high-risk disease as evidenced by UDCA treatment failure (frequently reflected in trial and clinical practice as an alkaline phosphatase >1.67 × upper limit of normal and/or elevated bilirubin) should be considered for second-line therapy, of which OCA is the only currently licensed National Institute for Health and Care Excellence recommended agent. Follow-up of patients is life-long and must address treatment of the disease and management of associated symptoms.

Understanding and Treating Pruritus in Primary Biliary Cholangitis

Pruritus is a common symptom with primary biliary cholangitis. Research has focused on refining understanding of the neurohumoral pathways involved in transduction of pruritus from peripheral cutaneous receptors to the central nervous system, and identifying modulating drugs. Current treatments have variable efficacy and safety. Because of the deleterious effects on quality of life or debilitation, many patients necessitate individualized therapeutic approaches; clinicians may need to consider invasive treatment options. This article highlights various therapeutic interventions, from general measures to invasive strategies, and novel agents under investigation, providing clinicians with the management tricks of the trade.

New Insights in Genetic Cholestasis: From Molecular Mechanisms to Clinical Implications

Cholestasis is characterised by impaired bile secretion and accumulation of bile salts in the organism. Hereditary cholestasis is a heterogeneous group of rare autosomal recessive liver disorders, which are characterised by intrahepatic cholestasis, pruritus, and jaundice and caused by defects in genes related to the secretion and transport of bile salts and lipids. Phenotypic manifestation is highly variable, ranging from progressive familial intrahepatic cholestasis (PFIC)-with onset in early infancy and progression to end-stage liver disease-to a milder intermittent mostly nonprogressive form known as benign recurrent intrahepatic cholestasis (BRIC). Cases have been reported of initially benign episodic cholestasis that subsequently transitions to a persistent progressive form of the disease. Therefore, BRIC and PFIC seem to represent two extremes of a continuous spectrum of phenotypes that comprise one disease. Thus far, five representatives of PFIC (named PFIC1-5) caused by pathogenic mutations present in both alleles of ATP8B1, ABCB11, ABCB4, TJP2, and NR1H4 have been described. In addition to familial intrahepatic cholestasis, partial defects in ATP8B1, ABCB11, and ABCB4 predispose patients to drug-induced cholestasis and intrahepatic cholestasis in pregnancy. This review summarises the current knowledge of the clinical manifestations, genetics, and molecular mechanisms of these diseases and briefly outlines the therapeutic options, both conservative and invasive, with an outlook for future personalised therapeutic strategies.

An update on the physiopathology and therapeutic management of cholestatic pruritus in children

Pruritus is a disabling symptom accompanying chronic cholestasis. In extreme cases, the refractory nature of pruritus can result in a need for invasive therapies including liver transplantation. The pathogenesis of pruritus in cholestatic disease is poorly understood. It may involve a specific neural pathway (similar to that associated with pain) regulated by several pruritogenic substances such as bile acids, opioids, serotonin, and the more recently identified lysophosphatidic acid. While the therapeutic management of cholestatic pruritus is well established in adults, there is no consensus in children, in light of the difficulty of conducting controlled clinical studies. The currently recommended strategy to manage cholestatic pruritus in children is based on several lines of specific therapies that should be associated with skin hydration and with non-specific treatment of cholestasis including ursodeoxycholic acid. Pruritus should be assessed as objectively as possible between each line of therapy. Rifampicin, a potent CYP3A4 inducer, is the first-line treatment of cholestatic pruritus. Second-line therapies require evaluation of the child in an expert center and are discussed on a case-by-case basis depending on the underlying disease and the experience of the center. These include inhibitors of serotonin reuptake (sertraline), opioid antagonists (naloxone), or ASBT inhibitors. Invasive therapies such as biliary diversion or liver transplantation can also be proposed in the most severe cases. The aim of the current update is to review the physiopathologic mechanisms implicated in cholestatic pruritus and to propose potential therapeutic strategies in children.

Low risk of hepatotoxicity from rifampicin when used for cholestatic pruritus: a cross-disease cohort study

BACKGROUND

The use of rifampicin for cholestatic pruritus is accompanied by concerns over safety, but the availability of real-world prescribing data is relatively limited.

AIM

We sought to describe the rate and characteristics of rifampicin-induced hepatitis in a mixed aetiology cohort of patients with established liver disease and cholestatic pruritus.

METHODS

Retrospective review of records for out-patients commenced on rifampicin for pruritus 2012-2016 inclusive. Rifampicin-induced hepatitis was recorded where alanine aminotransferase activity (ALT) increased to both ≥5 × baseline and ≥5 × upper limit of normal (ULN), or to both ≥3 × baseline and ≥3 × ULN with concurrent elevation in serum bilirubin to ≥2 × baseline and ≥2 × ULN, in addition to a Roussel-Uclaf Causality Assessment Method score of "probable" or "highly probable" for rifampicin causality.

RESULTS

After exclusions, we reviewed 105 patients who took rifampicin for a median of 131 days. Most had primary biliary cholangitis or primary sclerosing cholangitis; 40 (38.1%) were men and median age was 44 years (IQR: 32-57). 44 (41.9%) patients had baseline serum bilirubin ≥2 × ULN and 28 (26.7%) ALT ≥3 × ULN. 5 (4.8%) developed rifampicin-induced hepatitis at a median of 70(range 27-130) days after drug initiation. No individual or laboratory baseline characteristics were significantly associated with subsequent development of hepatitis. All cases of hepatitis recovered after drug cessation, although one patient was hospitalised and received corticosteroids.

CONCLUSIONS

Given the efficacy of rifampicin for an important sub-group of those with cholestatic pruritus, adult patients, including those with jaundice, can be counselled that 95% of prescriptions are safe, and where hepatitis occurs, including at long latency, drug cessation appears effective.

Drug-induced cholestasis

Cholestatic drug-induced liver injury (DILI) can be a diagnostic challenge due to a large differential diagnosis, variability in clinical presentation, and lack of serologic biomarkers associated with this condition. The clinical presentation of drug-induced cholestasis includes bland cholestasis, cholestatic hepatitis, secondary sclerosing cholangitis, and vanishing bile duct syndrome. The associate mortality of cholestatic DILI can be as high as 10%, and thus prompt recognition and removal of the offending agent is of critical importance. Several risk factors have been identified for drug-induced cholestasis, including older age, genetic determinants, and properties of certain medications. Antibiotics, particularly amoxicillin/clavulanate, remain the predominant cause of cholestatic DILI, although a variety of other medications associated with this condition have been identified. In this review, we summarize the presentation, clinical approach, risk factors, implicated medications, and management of drug-induced cholestatic liver injury. (Hepatology Communications 2017;1:726-735).

Bile acids and intestinal microbiota in autoimmune cholestatic liver diseases

Autoimmune cholestatic liver diseases, including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), are manifested as an impairment of normal bile flow and excessive accumulation of potentially toxic bile acids. Endogenous bile acids are involved in the pathogenesis and progression of cholestasis. Consequently, chronic cholestasis affects the expression of bile acid transporters and nuclear receptors, and results in liver injury. Several lines of evidence suggest that intestinal microbiota plays an important role in the etiopathogenesis of cholestatic liver diseases by regulating metabolism and immune responses. However, progression of the disease may also affect the composition of gut microbiota, which in turn exacerbates the progression of cholestasis. In addition, the interaction between intestinal microbiota and bile acids is not unidirectional. Bile acids can shape the gut microbiota community, and in turn, intestinal microbes are able to alter bile acid pool. In general, gut microbiota actively communicates with bile acids, and together play an important role in the pathogenesis of PBC and PSC. Targeting the link between bile acids and intestinal microbiota offers exciting new perspectives for the treatment of those cholestatic liver diseases. This review highlights current understanding of the interactions between bile acids and intestinal microbiota and their roles in autoimmune cholestatic liver diseases. Further, we postulate a bile acids-intestinal microbiota-cholestasis triangle in the pathogenesis of autoimmune cholestatic liver diseases and potential therapeutic strategies by targeting this triangle.

EASL Clinical Practice Guidelines: The diagnosis and management of patients with primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic inflammatory autoimmune cholestatic liver disease, which when untreated will culminate in end-stage biliary cirrhosis. Diagnosis is usually based on the presence of serum liver tests indicative of a cholestatic hepatitis in association with circulating antimitochondrial antibodies. Patient presentation and course can be diverse and risk stratification is important to ensure all patients receive a personalised approach to their care. The goals of treatment and management are the prevention of end-stage liver disease, and the amelioration of associated symptoms. Pharmacologic approaches in practice, to reduce the impact of the progressive nature of disease, currently include licensed therapies (ursodeoxycholic acid and obeticholic acid) and off-label therapies (fibric acid derivatives, budesonide). These clinical practice guidelines summarise the evidence for the importance of a structured, life-long and individualised, approach to the care of patients with PBC, providing a framework to help clinicians diagnose and effectively manage patients.

Fibrates for the treatment of cholestatic itch (FITCH): study protocol for a randomized controlled trial

BACKGROUND

Pruritus (itch) is a frequent, burdensome and difficult-to-treat symptom in patients with cholestasis. Fibrates are currently under investigation for the treatment of primary biliary cholangitis in patients with a suboptimal response to ursodeoxycholic acid. Moreover, there is empirical evidence for a possible antipruritic effect. We aim to prove this in a randomized controlled trial, including patients with cholestatic liver diseases other than primary biliary cholangitis that are accompanied by pruritus.

METHODS

A multicenter investigator-initiated, double-blind, randomized placebo-controlled trial to evaluate the effect of bezafibrate on cholestatic pruritus in 84 adult patients with primary biliary cholangitis or primary/secondary sclerosing cholangitis. Primary outcome is the proportion of patients with a reduction of itch intensity of 50% or more (measured on a Visual Analog Scale) after 21 days of treatment with bezafibrate 400 mg qid or placebo. Secondary outcomes include the effect of bezafibrate on a five-dimensional itch score, liver disease-specific quality of life, serum liver tests and autotaxin activity. Safety will be evaluated through serum parameters for kidney function and rhabdomyolysis as well as precise recording of (serious) adverse events. We provide a schematic overview of the study protocol and describe the methods used to recruit and randomize patients, collect and handle data and perform statistical analyses.

DISCUSSION

Given its favorable safety profile and anticholestatic properties, bezafibrate may become the new first-line treatment option for treating cholestatic pruritus.

TRIAL REGISTRATION

Netherlands Trial Register, ID: NCT02701166 . Registered on 2 March 2016; Netherlands Trial Register, ID: NTR5436 . Registered on 3 August 2015.

Management of cholestatic disease in 2017

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the most frequent chronic cholestatic liver diseases and serve as model diseases to discuss the management of cholestasis in 2017 in the lecture that is summarized in this report. PBC and PSC are characterized by inflammation and fibrosis of small intrahepatic (PBC) or larger intra- and/or extrahepatic (PSC) bile ducts. Bile duct damage leads to cholestasis and can progress to liver fibrosis and even cirrhosis. Various genetic, environmental and endogenous factors may contribute to the development of chronic cholestatic liver diseases, but the exact pathogenesis of PBC and PSC has not been clarified. Ursodeoxycholic acid (UDCA) is the standard treatment of PBC and is used also for other cholestatic conditions including PSC, and it exerts anticholestatic effects at adequate doses. Novel anticholestatic therapeutic options for patients not adequately responding to UDCA are under development or have, like obeticholic acid, already been proven to have efficacy when combined with UDCA in the treatment of PBC. The future role of immunomodulating/immunosuppressive drug regimens must be critically reviewed.

A systematic approach to the management of cholestatic pruritus in primary biliary cirrhosis

Pruritus (itch) is an important symptom of primary biliary cirrhosis (PBC), an archetypal cholestatic liver disease. Cholestatic pruritus can be a debilitating symptom causing significant deterioration in patients' quality of life. Effective management of pruritus in PBC involves awareness among clinicians to adequately assess its severity, and treatment with specific drug therapies in line with current practice guidelines. In PBC, antipruritic drugs are not universally effective and/or have significant side effects, and despite best efforts with various combinations of drugs, some patients remain significantly symptomatic, eventually opting for invasive or experimental treatments. Therefore, there is a clear unmet need for better alternative treatments for patients with refractory or intractable cholestatic pruritus. Recent advances in the understanding of pathogenesis of cholestatic pruritus and bile acid physiology have raised hopes for novel therapies, some of which are currently under trial. In this review, we aim to provide a practical guide to the management of this important and complex problem, discussing current knowledge and recent advances in the pathogenesis, summarise the evidence base for available therapeutic approaches and update potential novel future therapies for the management of pruritus in PBC.

Rifampicin Induces Bicarbonate-Rich Choleresis in Rats: Involvement of Anion Exchanger 2

BACKGROUND AND AIM

Previous studies have shown that rifampicin induced choleresis, the mechanisms of which have not been described. The aim of this study was to investigate the mechanisms underlying in vivo rifampicin-induced choleresis.

METHODS

In one experimental set, rats were treated chronically with rifampicin on days 1, 3 and 7. Serum and biliary parameters were assayed, and mRNA and protein levels, as well as the locations of the hepatic export transporters were analyzed by real-time PCR, western blot and immunofluorescence. Ductular mass was evaluated immunohistochemically. In another experimental set, rats received an acute infusion of rifampicin. The amount of rifampicin in bile was detected using HPLC. Biliary parameters were monitored following intrabiliary retrograde fluxes of the Cl(-)/HCO3 (-) exchange inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) in the infused rats.

RESULTS

Biliary bicarbonate output increased in parallel to the augmented bile flow in response to rifampicin, and this effect was abolished with intrabiliary administration of DIDS, but not NPPB. The biliary secretion of rifampicin with increases in bile flow and biliary rifampicin in response to different infused doses of the antibiotic show no significant correlations. After rifampicin treatment, the expression level of anion exchanger 2 (AE2) increased, while the location of hepatic transporters did not change. However, RIF treatment did not increase ductular mass significantly.

CONCLUSIONS

These results indicate that the increase in bile flow induced by rifampicin is mainly due to increased HCO3 (-) excretion mediated by increased AE2 protein expression and activity.

Pharmacology of bile acid receptors: Evolution of bile acids from simple detergents to complex signaling molecules

For many years, bile acids were thought to only function as detergents which solubilize fats and facilitate the uptake of fat-soluble vitamins in the intestine. Many early observations; however, demonstrated that bile acids regulate more complex processes, such as bile acids synthesis and immune cell function through activation of signal transduction pathways. These studies were the first to suggest that receptors may exist for bile acids. Ultimately, seminal studies by many investigators led to the discovery of several bile acid-activated receptors including the farnesoid X receptor, the vitamin D receptor, the pregnane X receptor, TGR5, α5 β1 integrin, and sphingosine-1-phosphate receptor 2. Several of these receptors are expressed outside of the gastrointestinal system, indicating that bile acids may have diverse functions throughout the body. Characterization of the functions of these receptors over the last two decades has identified many important roles for these receptors in regulation of bile acid synthesis, transport, and detoxification; regulation of glucose utilization; regulation of fatty acid synthesis and oxidation; regulation of immune cell function; regulation of energy expenditure; and regulation of neural processes such as gastric motility. Through these many functions, bile acids regulate many aspects of digestion ranging from uptake of essential vitamins to proper utilization of nutrients. Accordingly, within a short time period, bile acids moved beyond simple detergents and into the realm of complex signaling molecules. Because of the important processes that bile acids regulate through activation of receptors, drugs that target these receptors are under development for the treatment of several diseases, including cholestatic liver disease and metabolic syndrome. In this review, we will describe the various bile acid receptors, the signal transduction pathways activated by these receptors, and briefly discuss the physiological processes that these receptors regulate.

Rifampin (INN Rifampicin)

Therapeutic Reviews aim to provide essential independent information for health professionals about drugs used in palliative and hospice care. Additional content is available on www.palliativedrugs.com. Country-specific books (Hospice and Palliative Care Formulary USA, and Palliative Care Formulary, British and Canadian editions) are also available and can be ordered from www.palliativedrugs.com. The series editors welcome feedback on the articles (hq@palliativedrugs.com).

Drug treatment of pruritus in liver diseases

Pruritus (itch) is a common complication of cholestatic liver diseases (CLD). It can be a distressing and debilitating symptom, causing significant impairment in quality of life. Treatment of pruritus in liver diseases can be challenging and requires specific management with early initiation and a step-wise approach using specific drugs. Clinical trials are ongoing with novel agents that demonstrate potential efficacy. Patients with cholestatic pruritus are likely to present to a variety of clinicians who would benefit from medical awareness of available treatment options. In this review, we outline the pharmaceutical agents currently used to treat cholestatic pruritus and provide the evidence base for targeted symptom control of itch in liver diseases. We also highlight recent developments in the pathophysiology of cholestatic pruritus and the emerging novel therapies.