The effect of ursodeoxycholic acid therapy on the natural course of primary biliary cirrhosis

Primary biliary cirrhosis

Primary biliary cirrhosis is a chronic cholestatic liver disease characterised by destruction of small intrahepatic bile ducts, leading to fibrosis and potential cirrhosis through resulting complications. The serological hallmark of primary biliary cirrhosis is the antimitochondrial antibody, a highly disease-specific antibody identified in about 95% of patients with primary biliary cirrhosis. These patients usually have fatigue and pruritus, both of which occur independently of disease severity. The typical course of primary biliary cirrhosis has changed substantially with the introduöction of ursodeoxycholic acid (UDCA). Several randomised placebo-controlled studies have shown that UDCA improves transplant-free survival in primary biliary cirrhosis. However, about 40% of patients do not have a biochemical response to UDCA and would benefit from new therapies. Liver transplantation is a life-saving surgery with excellent outcomes for those with decompensated cirrhosis. Meanwhile, research on nuclear receptor hormones has led to the development of exciting new potential treatments. This Seminar will review the current understanding of the epidemiology, pathogenesis, and natural history of primary biliary cirrhosis, discuss management of the disease and its sequelae, and introduce research on new therapeutic options.

Autoantibody status and histological variables influence biochemical response to treatment and long-term outcomes in Japanese patients with primary biliary cirrhosis

AIM

The aim of the present study is to evaluate the factors influencing biochemical response to treatment and the value of biochemical response for predicting long-term outcomes in Japanese patients with primary biliary cirrhosis (PBC).

METHODS

Biochemical response to ursodeoxycholic acid (UDCA) or UDCA plus bezafibrate was defined as good (≤upper limit of normal [ULN]), fair (≤1.5 × ULN) or poor (>1.5 × ULN) at 2 years after initiation of UDCA treatment. Associations between various factors (including age, sex, autoantibody status and histological variables at baseline), biochemical response to treatment and long-term outcomes were evaluated in 164 Japanese PBC patients.

RESULTS

Anti-gp210 positivity and a higher bile duct loss score were significant risk factors for worse alkaline phosphatase (ALP) response (odds ratios [OR], 2.78 and 1.85, respectively). Age, anti-gp210 positivity and anticentromere positivity were significant risk factors for worse alanine aminotransferase (ALT) response (OR, 1.05, 4.0 and 2.77, respectively). Anti-gp210 positivity and a higher hepatitis score were significant risk factors for worse immunoglobulin (Ig)M response (OR, 2.10 and 2.06, respectively). Worse ALP and IgM response were significant risk factors for progression to late-stage disease without jaundice (OR, 2.27 and 2.32, respectively). Worse ALT response was a significant risk factor for progression to late-stage disease with persistent jaundice (OR, 11.11).

CONCLUSION

Biochemical response to treatment at 2 years, which is influenced by autoantibody status and histological variables at baseline, can predict long-term outcomes in Japanese patients with PBC.

Functional and structural features of cholangiocytes in health and disease

Cholangiocytes are the epithelial cells that line the bile ducts. Along the biliary tree, two different kinds of cholangiocytes exist; small and large cholangiocytes. Each type has important differences in their biological role in physiological and pathological conditions. In response to injury, cholangiocytes become reactive and acquire a neuroendocrine-like phenotype with the secretion of a number of peptides. These molecules act in an autocrine/paracrine fashion to modulate cholangiocyte biology and determine the evolution of biliary damage. The failure of such mechanisms is believed to influence the progression of cholangiopathies, a group of diseases that selectively target biliary cells. Therefore, the understanding of mechanisms regulating cholangiocyte response to injury is expected to foster the development of new therapeutic options to treat biliary diseases. In the present review, we will discuss the most recent findings in the mechanisms driving cholangiocyte adaptation to damage, with particular emphasis on molecular pathways that are susceptible of therapeutic intervention. Morphogenic pathways (Hippo, Notch, Hedgehog), which have been recently shown to regulate biliary ontogenesis and response to injury, will also be reviewed. In addition, the results of ongoing clinical trials evaluating new drugs for the treatment of cholangiopathies will be discussed.

A decline of LAMP- 2 predicts ursodeoxycholic acid response in primary biliary cirrhosis

Biochemical response to ursodeoxycholic acid (UDCA) in patients with primary biliary cirrhosis (PBC) is variable. We have previously reported that augmented expression of lysosome-associated membrane protein 2 (LAMP-2) was correlated with the severity of PBC. This study aimed to determine whether serum LAMP-2 could serve as a predictor of biochemical response to UDCA. The efficiency of serum LAMP-2 to predict biochemical response was assessed after 1 year of UDCA treatment in PBC patients by a retrospective analysis. We found that the basal serum LAMP-2 level was increased in PBC, especially in patients with stage III-IV (p = 0.010) or TBIL > 1 mg/dL (p = 0.014). Baseline serum LAMP-2 was higher in non-responders than that in responders, but the difference was statistically insignificant. However, after UDCA treatment, serum LAMP-2 level decreased prominently in the first 3 months, which was more obvious in responders. Further studies showed that the 35% decline of LAMP-2 after treatment for 3 months could be stated as an indicator of UDCA response with the sensitivity of 62.9% and specificity of 75.0% by Paris criteria. Meanwhile the specificity and sensitivity were identified as 63.5% and 64.1% by Barcelona criteria. Together, a decline in LAMP-2 might help to predict the response to UDCA.

New paradigms in the treatment of hepatic cholestasis: from UDCA to FXR, PXR and beyond

Cholestasis is an impairment of bile formation/flow at the level of the hepatocyte and/or cholangiocyte. The first, and for the moment, most established medical treatment is the natural bile acid (BA) ursodeoxycholic acid (UDCA). This secretagogue improves, e.g. in intrahepatic cholestasis of pregnancy or early stage primary biliary cirrhosis, impaired hepatocellular and cholangiocellular bile formation mainly by complex post-transcriptional mechanisms. The limited efficacy of UDCA in various cholestatic conditions urges for development of novel therapeutic approaches. These include nuclear and membrane receptor agonists and BA derivatives. The nuclear receptors farnesoid X receptor (FXR), retinoid X receptor (RXR), peroxisome proliferator-activated receptor α (PPARα), and pregnane X receptor (PXR) are transcriptional modifiers of bile formation and at present are under investigation as promising targets for therapeutic interventions in cholestatic disorders. The membrane receptors fibroblast growth factor receptor 4 (FGFR4) and apical sodium BA transporter (ASBT) deserve attention as additional therapeutic targets, as does the potential therapeutic agent norUDCA, a 23-C homologue of UDCA. Here, we provide an overview on established and future promising therapeutic agents and their potential molecular mechanisms and sites of action in cholestatic diseases.

Efficacy of obeticholic acid in patients with primary biliary cirrhosis and inadequate response to ursodeoxycholic acid

BACKGROUND & AIMS

We evaluated the efficacy and safety of obeticholic acid (OCA, α-ethylchenodeoxycholic acid) in a randomized controlled trial of patients with primary biliary cirrhosis who had an inadequate response to ursodeoxycholic acid therapy.

METHODS

We performed a double-blind study of 165 patients with primary biliary cirrhosis (95% women) and levels of alkaline phosphatase (ALP) 1.5- to 10-fold the upper limit of normal. Patients were randomly assigned to groups given 10 mg, 25 mg, or 50 mg doses of OCA or placebo, once daily for 3 months. Patients maintained their existing dose of ursodeoxycholic acid throughout the study. The primary outcome was change in level of ALP from baseline (day 0) until the end of the study (day 85 or early termination). We also performed an open-label extension of the trial in which 78 patients were enrolled and 61 completed the first year.

RESULTS

OCA was superior to placebo in achieving the primary end point. Subjects given OCA had statistically significant relative reductions in mean ALP from baseline to the end of the study (P < .0001 all OCA groups vs placebo). Levels of ALP decreased 21%-25% on average from baseline in the OCA groups and 3% in the placebo group. Sixty-nine percent (68 of 99) of patients given OCA had at least a 20% reduction in ALP compared with 8% (3 of 37) of patients given placebo (P < .0003). Among secondary end points, levels of γ-glutamyl transpeptidase decreased 48%-63%, on average, among subjects given OCA, vs a 7% decrease in the group given placebo; levels of alanine aminotransferase decreased 21%-35% on average among subjects given OCA vs none of the patients given placebo. Pruritus was the principal adverse event; incidence values in the OCA 10 mg, 25 mg, and 50 mg groups were 47% (not significantly different), 87% (P < .0003), and 80% (P < .006), respectively, vs 50% in the placebo group. In the extension study, levels of ALP continued to decrease to a mean level of 202 ± 11 U/L after 12 months vs 285 ± 15 U/L at baseline.

CONCLUSIONS

Daily doses of OCA, ranging from 10 to 50 mg, significantly reduced levels of ALP, γ-glutamyl transpeptidase, and alanine aminotransferase, compared with placebo, in patients with primary biliary cirrhosis who had inadequate responses to ursodeoxycholic acid. The incidence and severity of pruritus were lowest among patients who received 10 mg/d OCA. Biochemical responses to OCA were maintained in a 12-month open-label extension trial. ClinicalTrials.gov ID: NCT00550862.

Primary biliary cirrhosis: proposal for a new simple histological scoring system

BACKGROUND & AIMS

A simple and reproducible evaluation of non diagnostic histological lesions related to prognosis remains crucial in primary biliary cirrhosis (PBC). Presently there is no satisfactory simple scoring system analysing them reliably. We elaborated a semi-quantitative scoring system that assesses fibrosis, lymphocytic interface hepatitis (LIH) and ductopenia, separately. This study was aimed to evaluate its intra/interobserver reproducibility and its correlation with the main biochemical data.

METHODS

Liver biopsies from 33 consecutive newly diagnosed PBC patients were independently analysed by five liver pathologists. Fibrosis was classified into five stages (portal/periportal fibrosis/few septa/numerous septa/cirrhosis) and LIH into four grades. The bile duct ratio (BDR), i.e. ratio of the number of portal tracts with ducts to total number of portal tracts, Ludwig's and Scheuer's stages were evaluated. Intra and interobserver agreements were assessed. Histological results were correlated to the biochemical data.

RESULTS

Most patients had an early disease on clinical and biological parameters. The biopsies measured 23 mm on average (range 12 - 40 mm). Intraobserver reproducibility was substantial for fibrosis (κ = 0.68), LIH (κ = 0.69) and BDR (ICC = 0.69). Interobserver agreement for fibrosis was fair with the 5-class system (κ = 0.36), moderate with a 4-class system (κ = 0.56). moderate for LIH (κ = 0.59) and BDR (ICC = 0.50). Ludwig's and Scheuer's staging showed a fair interobserver agreement (κ = 0.32, κ = 0.31 respectively). Our system showed better correlations with biochemistry than Ludwig's and Scheuer's systems did.

CONCLUSIONS

This simple scoring system, assessing fibrosis, LIH and BDR separately, has a substantial intraobserver and a moderate interobserver reproducibility. Its prognostic relevance has to be evaluated.

Unmet clinical need in autoimmune liver diseases

Despite recent advances in understanding and treatment, there remain significant areas of unmet clinical need in each of the autoimmune liver diseases (AILDs). The evolving research landscape and emerging large patient cohorts are creating unique opportunities to translate science into new therapies and care pathways, with the potential to significantly improve the lives of AILD patients. However, the areas of unmet need represent real challenges, which need to be addressed, if this vision is to be realised. This review describes the areas of unmet need in AILD in adults relating to diagnostic and prognostic assessment, primary therapy, symptom management, trial design and delivery, and structured care delivery, with the aim of focusing future research prioritisation.

Combination therapy of bezafibrate and ursodeoxycholic acid for primary biliary cirrhosis: A meta-analysis

The aim of this study was to assess the efficiency and safety of combination therapy of ursodeoxycholic acid (UDCA) and bezafibrate for primary biliary cirrhosis. A meta-analysis of all long-term randomized controlled trials comparing the combination of UDCA and bezafibrate with UDCA monotherapy was performed via electronic searches. Seven trials, which included 177 patients, were assessed. Combination therapy with UDCA and bezafibrate was more effective than UDCA monotherapy in improving liver biochemistry, alkaline phosphatase (mean difference [MD], -146.15 IU/L; 95% confidence interval [CI], -193.58 to -98.72; P < 0.00001), γ-glutamyltransferase (MD, -20.64 IU/L; 95% CI, -30.86 to -10.43; P < 0.0001), immunoglobulin M (MD, -90.96 mg/dL; 95% CI, -137.36 to -44.56; P = 0.0001) and triglycerides (MD, -15.49 mg/dL; 95% CI, -30.25 to -0.74; P = 0.04). However, their effects on pruritus (odds ratio [OR], 0.82; 95% CI, 0.30-2.24; P = 0.70) and alanine aminotransferase (MD, -8.41 IU/L; 95% CI, -22.57 to 5.75; P = 0.24) did not differ significantly. This meta-analysis revealed no significant differences in the incidence of all-cause mortality (OR, 0.72; 95% CI, 0.10-5.49; P = 0.75) and adverse events (OR, 0.35; 95% CI, 0.07-1.84; P = 0.22) between patients treated with combination therapy and those treated with monotherapy. In this meta-analysis, combination therapy with UDCA and bezafibrate was more effective than UDCA monotherapy. Combination therapy improved liver biochemistry, but did not improve clinical symptoms, incidence of death or adverse events more effectively than monotherapy.

Levels of alkaline phosphatase and bilirubin are surrogate end points of outcomes of patients with primary biliary cirrhosis: an international follow-up study

BACKGROUND & AIMS

Noninvasive surrogate end points of long-term outcomes of patients with primary biliary cirrhosis (PBC) are needed to monitor disease progression and evaluate potential treatments. We performed a meta-analysis of individual patient data from cohort studies to evaluate whether patients' levels of alkaline phosphatase and bilirubin correlate with their outcomes and can be used as surrogate end points.

METHODS

We performed a meta-analysis of data from 4845 patients included in 15 North American and European long-term follow-up cohort studies. Levels of alkaline phosphatase and bilirubin were analyzed in different settings and subpopulations at different time points relative to the clinical end point (liver transplantation or death).

RESULTS

Of the 4845 patients, 1118 reached a clinical end point. The median follow-up period was 7.3 years; 77% survived for 10 years after study enrollment. Levels of alkaline phosphatase and bilirubin measured at study enrollment (baseline) and each year for 5 years were strongly associated with clinical outcomes (lower levels were associated with longer transplant-free survival). At 1 year after study enrollment, levels of alkaline phosphatase that were 2.0 times the upper limit of normal (ULN) best predicted patient outcome (C statistic, 0.71) but not significantly better than other thresholds. Of patients with alkaline phosphatase levels ≤ 2.0 times the ULN, 84% survived for 10 years compared with 62% of those with levels >2.0 times the ULN (P < .0001). Absolute levels of alkaline phosphatase 1 year after study enrollment predicted patient outcomes better than percentage change in level. One year after study enrollment, a bilirubin level 1.0 times the ULN best predicted patient transplant-free survival (C statistic, 0.79). Of patients with bilirubin levels ≤ 1.0 times the ULN, 86% survived for 10 years after study enrollment compared with 41% of those with levels >1.0 times the ULN (P < .0001). Combining levels of alkaline phosphatase and bilirubin increased the ability to predict patient survival times. We confirmed the predictive value of alkaline phosphatase and bilirubin levels in multiple subgroups, such as patients who had not received treatment with ursodeoxycholic acid, and at different time points after study enrollment.

CONCLUSIONS

Levels of alkaline phosphatase and bilirubin can predict outcomes (liver transplantation or death) of patients with PBC and might be used as surrogate end points in therapy trials.

Optimising risk stratification in primary biliary cirrhosis: AST/platelet ratio index predicts outcome independent of ursodeoxycholic acid response

BACKGROUND & AIMS

Outcomes in primary biliary cirrhosis (PBC) can be predicted by biochemical response to ursodeoxycholic acid (UDCA). Such stratification inadequately captures cirrhosis/portal hypertension, recognised factors associated with adverse events.

METHODS

We evaluated a cohort of PBC patients (n=386) attending the Liver Unit in Birmingham (derivation cohort), seeking to identify risk-variables associated with transplant-free survival independent of UDCA-response. A validation cohort was provided through well-characterised patients attending the Toronto Center for Liver Diseases (n=479) and Jena University Hospital (n=150).

RESULTS

On multivariate analysis, factors at diagnosis associated with liver transplant (LT)/death were patient age (HR:1.06; p<0.001), elevated bilirubin (HR:1.27; p<0.001), early-onset cirrhosis (HR:2.40; p<0.001) and baseline AST/platelet ratio index (APRI) (HR:1.95; p<0.001). At 1-year, UDCA biochemical non-response predicted poorer transplant-free survival, and additional factors (multivariate) associated with adverse outcome were age (HR:1.02; p<0.05) and 1-year APRI (HR:1.15; p<0.001). Obtaining a cut-point from our derivation cohort, APRI >0.54 at baseline was predictive of LT/death (adjusted HR: 2.40; p<0.001), and retained statistical significance when applied at 1-year (APRI-r1, adjusted HR:2.75; p<0.001) despite controlling for UDCA-response. Across both cohorts, transplant-free survival was poorer for biochemical-responders with an APRI-r1 >0.54 vs. biochemical-responders with a lower APRI-r1 (p<0.01 and p<0.001, respectively); non-responders with high APRI-r1 had the poorest outcomes (p<0.001 and p<0.001).

CONCLUSION

In PBC, elevated APRI is associated with future risk of adverse events, independently and additively of UDCA-response. This cross-centre, robustly validated observation will contribute to ongoing efforts to refine existing risk-stratification tools, as well as direct focus for new therapies in patients with PBC.

Fibrate treatment for primary biliary cirrhosis

PURPOSE OF REVIEW

Primary biliary cirrhosis (PBC) can lead to end-stage liver disease and death. Ursodeoxycholic acid (UDCA) treatment can normalize serum liver enzymes in PBC, and such UDCA-responsive patients have a similar life expectancy as age and sex-matched controls. Nearly up to 50% of the patients with PBC, depending on sex and age at diagnosis, show an incomplete biochemical response to UDCA and require additional/alternative treatment. The purpose of this review is to critically evaluate the molecular mechanisms and clinical benefit of fibrate treatment in these patients.

RECENT FINDINGS

Fibrates have anticholestatic, anti-inflammatory, and antifibrotic effects in animal and in-vitro studies. The mechanisms that underlie these effects are complementary, and largely mediated through activation of peroxisome proliferator activated receptors. Fibrate treatment ameliorated liver biochemical tests in UDCA unresponsive patients, either as mono-therapy or in combination with UDCA. These results, however, were obtained in case series and small pilot studies. The results of phase III studies, such as the Bezafibrate in Combination With Ursodeoxycholic Acid in Primary Biliary Cirrhosis (BEZURSO) trial, are currently awaited.

SUMMARY

A considerable body of observational evidence supports the safety and efficacy of fibrate treatment in PBC patients with an incomplete response to UDCA. These results encourage the evaluation of its effects on liver-related morbidity and mortality in larger clinical trials.

Primary biliary cirrhosis in adults

Primary biliary cirrhosis (PBC) is a chronic, autoimmune, cholestatic liver disease. It is characterized by slow destruction of small intrahepatic bile ducts, impaired biliary secretion and stasis of toxic endogenous bile acids within the liver with progression to liver fibrosis and cirrhosis. It has an increasing prevalence worldwide. It occurs more commonly in women than men at a ratio of 10:1. In most cases, diagnosis relies on a positive antimitochondrial antibody in the context of chronic cholestasis, without the need for a liver biopsy. Ursodeoxycholic acid improves survival even in patients with advanced liver disease. Certain findings such as fatigue, anti-nuclear antibodies, anti-centromere antibodies and the GP210 antinuclear antibody predict a poor outcome. Up to 40% of patients do not respond satisfactorily to ursodeoxycholic acid therapy and should be considered for adjunctive therapies. Several adjunctive and newer therapies are being tested and some appear promising. We provide a review of PBC with a focus on advances in therapies that may impact the management of PBC in the near future.

Ursodeoxycholic Acid ameliorates pain severity and cartilage degeneration in monosodium iodoacetate-induced osteoarthritis in rats

Osteoarthritis (OA) is a degenerative joint disease characterized by a progressive loss of cartilage. And, increased oxidative stress plays a relevant role in the pathogenesis of OA. Ursodeoxycholic acid (UDCA) is a used drug for liver diseases known for its free radical-scavenging property. The objectives of this study were to investigate the in vivo effects of UDCA on pain severity and cartilage degeneration using an experimental OA model and to explore its mode of actions. OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA) to the knee. Oral administration UDCA was initiated on the day of MIA injection. Limb nociception was assessed by measuring the paw withdrawal latency and threshold. Samples were analyzed macroscopically and histologically. Immunohistochemistry was used to investigate the expression of interleukin-1β (IL-1β), IL-6, nitrotyrosine and inducible nitric oxide synthase (iNOS) in knee joints. UDCA showed an antinociceptive property and attenuated cartilage degeneration. OA rats given oral UDCA significantly exhibited a decreased number of osteoclasts in subchondral bone legion compared with the vehicle-treated OA group. UDCA reduced the expression of IL-1β, IL-6, nitrotyrosine and iNOS in articular cartilage. UDCA treatment significantly attenuated the mRNA expression of matrix metalloproteinase-3 (MMP-3), -13, and ADAMTS5 in IL-1β-stimulated human OA chondrocytes. These results show the inhibitory effects of UDCA on pain production and cartilage degeneration in experimentally induced OA. The chondroprotective properties of UDCA were achieved by suppressing oxidative damage and inhibiting catabolic factors that are implicated in the pathogenesis of cartilage damage in OA.

Waiting list mortality of patients with primary biliary cirrhosis in the Japanese transplant allocation system

BACKGROUND

The present study aimed to evaluate etiology-based differences in the risk of waiting list mortality, and to compare the current Japanese transplant allocation system with the Child-Turcotte-Pugh (CTP) and the Model for End-Stage Liver Disease (MELD) scoring systems with regard to the risk of waiting list mortality in patients with primary biliary cirrhosis (PBC).

METHODS

Using data derived from all adult candidates for deceased donor liver transplantation in Japan from 1997 to 2011, we assessed factors associated with waiting list mortality by the Cox proportional hazards model. The waiting list mortality risk of PBC patients was further estimated with adjustment for each scoring system.

RESULTS

Of the 1056 patients meeting the inclusion criteria, 743 were not on the list at the end of study period; waiting list mortality was 58.1 % in this group. In multivariate analysis, increasing age and PBC were significantly associated with an increased risk of waiting list mortality. In comparison with patients with hepatitis C virus (HCV) infection, PBC patients were at 79 % increased risk and had a shorter median survival time by approximately 8 months. The relative hazard of PBC patients was statistically significant with adjustment for CTP score and medical point score, which was the priority for ranking candidates in the Japanese allocation system. However, it lost significance with adjustment for MELD score. Stratification by MELD score indicated a comparable waiting list survival time between patients with PBC and HCV.

CONCLUSIONS

PBC patients are at high risk of waiting list mortality in the current allocation system. MELD-based allocation could reduce this risk.

Genetic polymorphisms of OCT-1 confer susceptibility to severe progression of primary biliary cirrhosis in Japanese patients

BACKGROUND

To identify the genetic factors involved in the pathogenesis of primary biliary cirrhosis (PBC), we focused on the organic cation transporter 1 (OCT1/SLC22A1), which is closely associated with phosphatidylcholine synthesis in hepatocytes.

METHODS

We selected four (rs683369, rs2282143, rs622342 and rs1443844) OCT-1 single nucleotide polymorphisms (SNPs), and genotyped these SNPs using the TaqMan probe method in 275 Japanese PBC patients and 194 gender-matched, healthy volunteers as controls.

RESULTS

The Chi-square test revealed that the rs683369 variant allele (G) was associated with insusceptibility to PBC development [P = 0.009, odds ratio (OR) 0.60, 95 % confidence interval (CI) 0.40-0.88] in an allele model, and that the rs683369 variant allele (G) was associated with jaundice-type progression in a minor allele dominant genotype model (P = 0.032, OR 3.10, 95 % CI 1.05-9.14). The OCT-1 rs2282143 variant (T) and rs622342 variant (C) were also associated with jaundice-type progression in a minor allele recessive genotype model (P = 0.0002, OR 10.58, 95 % CI 2.36-47.54, and P = 0.006, OR 7.84, 95 % CI 1.39-44.36, respectively). Furthermore, the association of OCT-1 rs683369 and rs622342 with susceptibility to jaundice-type progression was confirmed by a replication study with a distinct set of PBC patients who underwent liver transplantation.

CONCLUSIONS

The present study is the first report on the association of OCT-1 genetic polymorphisms with the overall development and jaundice-type progression of PBC.

Role of AE2 for pHi regulation in biliary epithelial cells

The Cl⁻/HCO⁻₃anion exchanger 2 (AE2) is known to be involved in intracellular pH (pH_i) regulation and transepithelial acid-base transport. Early studies showed that AE2 gene expression is reduced in liver biopsies and blood mononuclear cells from patients with primary biliary cirrhosis (PBC), a disease characterized by chronic non-suppurative cholangitis associated with antimitochondrial antibodies (AMA) and other autoimmune phenomena. Microfluorimetric analysis of the Cl⁻/HCO⁻₃ anion exchange (AE) in isolated cholangiocytes showed that the cAMP-stimulated AE activity is diminished in PBC compared to both healthy and diseased controls. More recently, it was found that miR-506 is upregulated in cholangiocytes of PBC patients and that AE2 may be a target of miR-506. Additional evidence for a pathogenic role of AE2 dysregulation in PBC was obtained with Ae2^−/−_a,b mice, which develop biochemical, histological, and immunologic alterations that resemble PBC (including development of serum AMA). Analysis of HCO⁻₃ transport systems and pH_i regulation in cholangiocytes from normal and Ae2^−/−_a,b mice confirmed that AE2 is the transporter responsible for the Cl⁻/HCO⁻₃exchange in these cells. On the other hand, both Ae2^+/+_a,b and Ae2^−/−_a,b mouse cholangiocytes exhibited a Cl⁻-independent bicarbonate transport system, essentially a Na⁺-bicarbonate cotransport (NBC) system, which could contribute to pH_i regulation in the absence of AE2.

The diagnosis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic liver disease characterized by the immune mediated destruction of small intrahepatic bile duct epithelial cells leading to cholestasis and cirrhosis. The autoimmune basis of PBC is supported by the highly specific anti-mitochondrial antibodies (AMAs) and autoreactive T cells, the former being the basis for diagnosis in the vast majority of cases. Although a rare disease, the incidence rates of PBC have been increasing, possibly due to increased testing and diagnosis as opposed to a true increase in disease incidence. Presently, most cases are asymptomatic and only suspected based upon routine liver tests. Those with symptoms typically complain of pruritus and fatigue. The diagnosis of PBC is based on the presence of at least 2 of 3 key criteria including a persistently elevated serum alkaline phosphatase, the presence of serum AMAs, and liver histology consistent with PBC. Anti-nuclear antibodies specific to PBC are useful in cases in which AMAs are not detected and may indicate a more aggressive course. Ursodeoxycholic acid is the only proven therapy for PBC and in most cases can delay or prevent disease progression. However, a subgroup of patients does not adequately respond to ursodeoxycholic acid and for whom new therapies are needed.

Cholestatic liver disease

The care of the patient with cholestasis hinges on identifying the etiology, treating reversible causes, and managing chronic cholestatic processes. PBC and PSC are important causes of chronic cholestasis, and are the most common causes of cholestatic liver disease. Effective therapy is available for patients with PBC, whereas none exists for patients with PSC. Awareness of the complications that may be associated with cholestasis and implementing the appropriate management are essential.

Biochemical criteria at 1 year are not robust indicators of response to ursodeoxycholic acid in early primary biliary cirrhosis: results from a 29-year cohort study

BACKGROUND

In primary biliary cirrhosis (PBC), biochemical criteria at 1 year are considered surrogates of response to ursodeoxycholic acid (UDCA). However, due to the slow natural history of PBC, evaluation at 1 year may be suboptimal to assess the therapeutic response, particularly in early disease.

AIM

To determine whether evaluation of biochemical criteria at 1 year is a reliable surrogate of UDCA response in early PBC.

METHODS

We analysed the prospectively collected data of 215 patients (untreated = 129; UDCA-treated = 86) with early PBC (normal baseline bilirubin/albumin) and a median follow-up of 8 years (range: 1-29.1). The 1-year attainment rates of the Barcelona, Paris-I, Paris-II and Toronto definitions, and their predictive relevance for a poor outcome (death, transplantation, complications of cirrhosis), were assessed either as a result of UDCA or no treatment. Independent associations with attaining each UDCA response definition were identified by multivariate analysis.

RESULTS

Untreated patients displayed 1-year biochemical features compatible with 'treatment response' at rates (Barcelona: 36.4%, Paris-I: 66.7%, Toronto: 59.7%, Paris-II: 40.3%) similar to those obtained under UDCA. Depending on the definition, baseline ALP≤3xULN (OR: 4.80-35.90), AST≤2xULN (OR: 5.63-9.34) and early histological stage (OR: 3.67-3.87) were the stronger predictors for attaining the criteria. UDCA treatment was associated with attaining Barcelona (OR = 2.16) and Paris-II (OR = 2.84), but not Paris-I, and not Toronto definition when excluding late histological cases. Paris-I criteria were significantly predictive of long-term outcomes (HR = 2.83) in untreated patients.

CONCLUSIONS

In early PBC, biochemical criteria at 1 year reflect severity of the disease rather than the therapeutic response to UDCA.

Vitamin D in autoimmune liver disease

The development of autoimmune disease is based on the interaction of genetic susceptibility and environmental causes. Environmental factors include infectious and non-infectious agents, with some of these factors being implicated in several autoimmune diseases. Vitamin D is now believed to play a role in the development (or prevention) of several autoimmune diseases, based on its immunomodulatory properties. As well, the increasing incidence of autoimmune disease as one moves away from the equator, may be due to the lack of sunlight, which is crucial for the maintenance of normal vitamin D levels. A deficiency in vitamin D levels or vitamin D receptors is commonly indicated in autoimmune diseases, with multiple sclerosis (MS) being one of the best-studied and well-known examples. However, the role of vitamin D in other autoimmune diseases is not well defined, including autoimmune liver diseases such as primary biliary cirrhosis, autoimmune hepatitis, and primary sclerosing cholangitis. This review will examine the role of vitamin D as an immunomodulator, followed by a comparison of vitamin D in MS versus autoimmune liver disease. From this comparison, it will become clear that vitamin D likely plays a role in the development of autoimmune liver disease, but this area requires further investigation.

Cost and health consequences of treatment of primary biliary cirrhosis with ursodeoxycholic acid

BACKGROUND

Long-term use of ursodeoxycholic acid (UDCA) is the recommended therapy in primary biliary cirrhosis (PBC). The lifetime effectiveness and cost-effectiveness of UDCA in PBC have, however, not been assessed.

AIM

To estimate the health outcomes and lifetime costs of a Norwegian cohort of PBC patients on UDCA.

METHODS

Norwegian PBC patients (n = 182) (90% females; mean age 56.3 ± 8.9 years; Mayo risk score 4.38) who were included in a 5-year open-label study of UDCA therapy were subsequently followed up for up to 11.5 years. The lifetime survival was estimated using a Weibull survival model. The survival benefit from UDCA was based on a randomised clinical trial from Canada, comparing the effect of non-UDCA and UDCA. Survival and costs of standard care vs. standard care plus UDCA were simulated in a Markov model with death and liver transplantation as major events, invoking transition of a patient's state in the model.

RESULTS

The gain in life expectancy for a PBC patient on UDCA compared with standard care was 2.24 years (1.19 years discounted). The lifetime treatment costs were EUR 151,403 and EUR 157,741 (EUR 102,912 and EUR 115,031 discounted) for patients with and without UDCA respectively. A probabilistic sensitivity analysis indicated an 82% probability that UDCA entails both greater life expectancy and lower costs than standard care.

CONCLUSIONS

The results of this study indicate that UDCA therapy is a dominant strategy as it confers reduced morbidity and mortality, as well as cost savings, compared with standard therapy.

The immunophysiology and apoptosis of biliary epithelial cells: primary biliary cirrhosis and primary sclerosing cholangitis

Biliary epithelial cells (BECs) provide the first line of defense against lumenal microbes in the biliary system. BECs express a variety of pathogen recognition receptors and can activate several intracellular signaling cascades to initiate antimicrobial defenses, including production of several anti-microbial peptides, cytokines, chemokines, and adhesion molecules. BECs also secrete immunoglobulin A and interact with other cells through expression and release of adhesion molecules and immune mediators. Recently, several reports suggest a correlation between apoptosis and autoimmunity through ineffective clearance of self-antigens. Primary biliary cirrhosis (PBC) is a slowly progressive, autoimmune cholestatic liver disease characterized by highly specific antimitochondrial antibodies (AMAs) and the specific immune-mediated destruction of BECs. We have demonstrated that the AMA self-antigen, namely the E2 subunit of the pyruvate dehydrogenase complex, is detectable in its antigenically reactive form within apoptotic blebs from human intrahepatic biliary epithelial cells and activates innate immune responses. Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by inflammation and the presence of concentric fibrosis of intrahepatic and/or extrahepatic bile ducts, eventually leading to cirrhosis. However, apoptosis does not appear to play a central role in PSC. Despite both diseases involving immune-mediated injury to bile ducts, apoptosis occurs more commonly overall in PBC where it likely plays a unique role.

Impact of primary biliary cirrhosis on perceived quality of life: the UK-PBC national study

Primary biliary cirrhosis (PBC) has a complex clinical phenotype, with debate about the extent and specificity of frequently described systemic symptoms such as fatigue. The aim of this study was to use a national patient cohort of 2,353 patients recruited from all clinical centers in the UK to explore the impact of disease on perceived life quality. Clinical data regarding diagnosis, therapy, and biochemical status were collected and have been reported previously. Detailed symptom phenotyping using recognized and validated symptom assessment tools including the PBC-40 was also undertaken and is reported here. Perception of poor quality of life and impaired health status was common in PBC patients (35% and 46%, respectively) and more common than in an age-matched and sex-matched community control group (6% and 15%, P < 0.0001 for both). Fatigue and symptoms of social dysfunction were associated with impaired perceived quality of life using multivariate analysis. Fatigue was the symptom with the greatest impact. Depression was a significant factor, but appeared to be a manifestation of complex symptom burden rather than a primary event. Fatigue had its greatest impact on perceived quality of life when accompanied by symptoms of social dysfunction, suggesting that maintenance of social networks is critical for minimizing the impact of fatigue.

CONCLUSION

The symptom burden in PBC, which is unrelated to disease severity or ursodeoxycholic acid response, is significant and complex and results in significant quality of life deficit. The complexity of symptom burden, and its lack of relation to disease severity and treatment response, suggest that specific approaches to symptom management are warranted that address both symptom biology and social impact.

Early biochemical response to ursodeoxycholic acid and long-term prognosis of primary biliary cirrhosis: results of a 14-year cohort study

The biochemical response to ursodeoxycholic acid (UDCA) in primary biliary cirrhosis is a strong predictor of long-term outcome and thus facilitates the rapid identification of patients needing new therapeutic approaches. Numerous criteria for predicting outcome of treatment have been studied based on biochemical response to UDCA at 1 year. We sought to determine whether an earlier biochemical response at 3 or 6 months could as efficiently identify patients at risk of poor outcome, as defined by liver-related death, liver transplantation, and complications of cirrhosis. We analyzed the prospectively collected data of 187 patients with a median follow-up of 5.8 years (range, 1.3-14 years). The survival rates without adverse outcome at 5 years and 10 years were 86% and 63%. Under UDCA therapy, laboratory liver parameters experienced the most prominent improvement in the first 3 months (P < 0.0001) and then stayed relatively stable for the following months. The Paris, Barcelona, Toronto, and Ehime definitions, but not the Rotterdam definition, applied at 3, 6, and 12 months significantly discriminated the patients in terms of long-term outcome. Compared with biochemical responses evaluated after 1 year of UDCA therapy, biochemical responses at the third month demonstrated higher positive predictive value (PPV) but lower negative predictive value (NPV) and increased negative likelihood ratio (NLR) by all definitions; biochemical responses at the sixth month showed higher or the same PPV and NPV and lower NLR by all definitions.

CONCLUSION

For the previously published criteria, biochemical responses at the sixth month can be used in place of those evaluated after 1 year of UDCA therapy. Our findings justify a more rapid identification of patients who need new therapeutic approaches.

Primary biliary cirrhosis: therapeutic advances

Primary biliary cirrhosis (PBC) is a chronic and slowly progressive cholestatic liver disease characterized by destruction of the interlobular bile ducts, which, if untreated, leads to fibrosis, biliary cirrhosis, and liver failure. Because liver transplantation remains the only curative option for PBC, the goals of treatment are to slow the rate of progression, to alleviate related symptoms, and to prevent complications. Ursodeoxycholic acid is the only US Food and Drug Administration-approved medical treatment of PBC. Several agents are undergoing evaluation as monotherapy or as an adjuvant to ursodeoxycholic acid. This review summarizes current therapeutic advances in the care of patients with PBC.

Liver transplant for cholestatic liver diseases

Cholestatic liver diseases include a group of diverse disorders with different epidemiology, pathophysiology, clinical course, and prognosis. Despite significant advances in the clinical care of patients with cholestatic liver diseases, liver transplant (LT) remains the only definitive therapy for end-stage liver disease, regardless of the underlying cause. As per the United Network for Organ Sharing database, the rate of cadaveric LT for cholestatic liver disease was 18% in 1991, 10% in 2000, and 7.8% in 2008. This review summarizes the available evidence on various common and rare cholestatic liver diseases, disease-specific issues, and pertinent aspects of LT.

Anticholestatic effects of bezafibrate in patients with primary biliary cirrhosis treated with ursodeoxycholic acid

Bezafibrate is a widely used hypolipidemic agent and is known as a ligand of the peroxisome proliferator-activated receptors (PPARs). Recently this agent has come to be recognized as a potential anticholestatic medicine for the treatment of primary biliary cirrhosis (PBC) that does not respond sufficiently to ursodeoxycholic acid (UDCA) monotherapy. The aim of this study was to explore the anticholestatic mechanisms of bezafibrate by analyzing serum lipid biomarkers in PBC patients and by cell-based enzymatic and gene expression assays. Nineteen patients with early-stage PBC and an incomplete biochemical response to UDCA (600 mg/day) monotherapy were treated with the same dose of UDCA plus bezafibrate (400 mg/day) for 3 months. In addition to the significant improvement of serum biliary enzymes, immunoglobulin M (IgM), cholesterol, and triglyceride concentrations in patients treated with bezafibrate, reduction of 7α-hydroxy-4-cholesten-3-one (C4), a marker of bile acid synthesis, and increase of 4β-hydroxycholesterol, a marker of CYP3A4/5 activity, were observed. In vitro experiments using human hepatoma cell lines demonstrated that bezafibrate controlled the target genes of PPARα, as well as those of the pregnane X receptor (PXR); down-regulating CYP7A1, CYP27A1, and sinusoidal Na(+) /taurocholate cotransporting polypeptide (NTCP), and up-regulating CYP3A4, canalicular multidrug resistance protein 3 (MDR3), MDR1, and multidrug resistance-associated protein 2 (MRP2).

CONCLUSION

Bezafibrate is a dual PPARs/PXR agonist with potent anticholestatic efficacy in early-stage PBC patients with an incomplete biochemical response to UDCA monotherapy.

Care of the cholestatic patient

Cholestasis is defined as impairment of bile formation or bile flow. Care of the patient with cholestatic features is dependent on identifying the cause of the cholestasis, initiating appropriate treatment of reversible conditions, and the recognition and management of cholestasis-specific complications. Cholestasis may include extrahepatic ducts and intrahepatic bile ducts, or may be limited to one or the other. Jaundice and pruritus are the hallmarks of cholestasis clinically but biochemical evidence may, and often does, precede the clinical manifestations.

Value of baseline platelet count for prediction of complications in primary biliary cirrhosis patients treated with ursodeoxycholic acid

BACKGROUND

Decreased platelet count has been observed in various liver diseases, but its significance in primary biliary cirrhosis (PBC) remains unknown. The present study aimed to evaluate the predictive value of the platelet count at diagnosis for PBC-related complications in patients newly diagnosed with PBC and treated with ursodeoxycholic acid (UDCA).

METHODS

Ninety-six PBC patients without complications treated with UDCA immediately after diagnosis were retrospectively reviewed. All hematologic and chemical parameters, Mayo risk score and PBC-related complications including upper gastrointestinal hemorrhage, presence of ascites, serum bilirubin concentration > 102.6 μmol/L and onset of hepatic encephalopathy were extracted. The associations between these parameters at diagnosis and complications were determined and the prognostic value of the platelet count was evaluated by receiver operating characteristics (ROC) analysis, Kaplan-Meier method and Cox proportional hazard model with the hazard ratio (HR) and 95% confidence interval (CI) calculated.

RESULTS

Patients with PBC-related complications had significantly decreased platelet count and serum bilirubin concentration, prolonged prothrombin time, and increased Mayo risk score compared to those without complications. A platelet count of ≤ 132.5 × 10(9)/L was associated with the occurrence of complications, with an area under the ROC curve of 0.74 (95% CI: 0.64-0.85). The association remained even after adjustment for Mayo risk score (HR: 2.85; 95% CI: 1.46-5.54; p < 0.01), as shown in the Cox proportional hazard model.

CONCLUSIONS

Decreased platelet count is a predictive factor for PBC-related complications. A cut-off value of ≤ 132.5 × 10(9)/L is recommended for the baseline platelet count to predict complications in patients newly diagnosed with PBC and treated with UDCA.

Liver involvement in Turner syndrome

Liver test abnormalities are frequent in adult patients with Turner syndrome, corresponding to various pathophysiological mechanisms. Steatosis, steatofibrosis and steatohepatitis are the most frequently reported lesions, caused by metabolic disorders, which are commonly related to overweight. Marked architectural changes, including nodular regenerative hyperplasia, multiple focal nodular hyperplasia and cirrhosis, found in some patients, are associated with a risk of severe liver-related complications. Architectural changes are often observed and are associated with vascular disorders caused by congenitally abnormal vessels. Finally, small bile duct alterations resembling sclerosing cholangitis occur in several patients. Oestrogen replacement therapy does not cause liver toxicity in patients with Turner syndrome and is not contraindicated in case of elevated liver enzymes. Moreover, in recent studies, oestrogen therapy was reported to improve liver function tests. Because of the wide spectrum of potential liver injuries that may occur in Turner syndrome patients, a regular screening of liver enzymes is recommended for early detection and treatment.

Natural history and management of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic inflammatory autoimmune disease that mainly targets the cholangiocytes of the interlobular bile ducts in the liver. It is a rare disease with prevalence of less than one in 2000. Its prevalence in developing countries is increasing presumably because of growth in recognition and knowledge of the disease. PBC is thought to result from a combination of multiple genetic factors and superimposed environmental triggers. The contribution of the genetic predisposition is evidenced by familial clustering. Several risk factors, including exposure to infectious agents and chemical xenobiotics, have been suggested. Common symptoms of the disease are fatigue and pruritus, but most patients are asymptomatic at first presentation. The prognosis of PBC has improved because of early diagnosis and use of ursodeoxycholic acid, the only established medical treatment for this disorder. When administered at adequate doses of 13–15 mg/kg/day, up to two out of three patients with PBC may have a normal life expectancy without additional therapeutic measures. However, some patients do not respond adequately to ursodeoxycholic acid and might need alternative therapeutic approaches.

Current pharmacotherapy for cholestatic liver disease

IMPORTANCE OF THE FIELD

The cholestatic liver diseases comprise a heterogeneous group of disorders which, left untreated, usually progresses to cirrhosis and liver failure. Most are recognized before the onset of advanced fibrosis, thereby affording an opportunity for disease modifying therapy.

AREAS COVERED

This review will cover the current pharmacologic management of the most common causes of cholestatic liver disease in adults, including primary biliary cirrhosis, primary biliary cirrhosis-autoimmune hepatitis overlap syndrome, primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, intestinal failure-associated liver disease, and immunoglobulin G4-associated cholangitis. Pharmacologic management of complications of cholestasis will also be reviewed.

EXPERT OPINION

Effective therapy for most cholestatic liver disease is lacking. Ursodeoxycholic acid (UDCA) slows the progression of primary biliary cirrhosis but the majority of patients do not have a full response. Even in those with a complete response, UDCA does not cure the disease. There is currently no effective medical therapy for primary sclerosing cholangitis. Symptoms and serum liver biochemistry values in intrahepatic cholestasis of pregnancy are improved with UDCA, but it is not certain if this alters the course of disease. Immunoglobulin G4-associated cholangitis is responsive to steroids but may relapse. The farnesoid X receptor agonists are a promising new class of drugs currently being tested in cholestatic liver disease.

Primary biliary cirrhosis-specific autoantibodies in first degree relatives of Greek primary biliary cirrhosis patients

AIM: To determine the prevalence and significance of primary biliary cirrhosis (PBC)-specific autoantibodies in first-degree relatives (FDRs) of Greek PBC patients.

METHODS: The presence of antimitochondrial antibodies (AMA) and PBC-specific antinuclear antibodies (ANA) were determined using indirect immunofluorescence assays, dot-blot assays, and molecularly based enzyme-linked immunosorbent assays in 101 asymptomatic for liver-related symptoms FDRs of 44 PBC patients. In order to specify our results, the same investigation was performed in 40 healthy controls and in a disease control group consisting of 40 asymptomatic for liver-related symptoms FDRs of patients with other autoimmune liver diseases namely, autoimmune hepatitis-1 or primary sclerosing cholangitis (AIH-1/PSC).

RESULTS: AMA positivity was observed in 19 (only 4 with abnormal liver function tests) FDRs of PBC patients and none of the healthy controls. The prevalence of AMA was significantly higher in FDRs of PBC patients than in AIH-1/PSC FDRs and healthy controls [18.8%, 95% confidence interval (CI): 12%-28.1% vs 2.5%, 95% CI: 0.1%-14.7%, P = 0.01; 18.8%, 95% CI: 12%-28.1% vs 0%, 95% CI: 0%-10.9%, P = 0.003, respectively]. PBC-specific ANA positivity was observed in only one FDR from a PSC patient. Multivariate analysis showed that having a proband with PBC independently associated with AMA positivity (odds ratio: 11.24, 95% CI: 1.27-25.34, P = 0.03) whereas among the investigated comorbidities and risk factors, a positive past history for urinary tract infections (UTI) was also independently associated with AMA detection in FDRs of PBC patients (odds ratio: 3.92, 95% CI: 1.25-12.35, P = 0.02).

CONCLUSION: In FDRs of Greek PBC patients, AMA prevalence is significantly increased and independently associated with past UTI. PBC-specific ANA were not detected in anyone of PBC FDRs.

Primary biliary cirrhosis and bile acids

The dihydroxylated bile acid ursodeoxycholic acid (UDCA) has now been regarded for 20 years as the standard treatment for primary biliary cirrhosis (PBC), a chronic cholestatic immune-mediated condition marked by progressive destruction of small intrahepatic bile ducts, impaired biliary secretion, hepatocellular retention of toxic endogenous bile acids and, ultimately, the development of fibrosis leading to cirrhosis that commonly requires liver transplantation. At first sight, it seems intriguing that a bile acid could be considered for use as a therapeutic agent in a bile-acid secretion disorder. Yet, in addition to its inherently greater hydrophilic nature and competitive effect on endogenous bileacid recycling, UDCA has indeed been demonstrated to be a potent post-transcriptional secretagogue as well as a potential anti-inflammatory and anti-apoptotic agent. While the combined glucocorticoid receptor/pregnane X receptor (PXR) agonist budesonide, in combinaison with UDCA, has been shown to exert additional beneficial effects in PBC, significant progress in understanding the regulatory mechanisms involved in bile-acid homeostasis has led to the identification of nuclear [farnesoid X receptor (FXR), PXR, peroxisome proliferator-activated receptor alpha (PPARα)] and membrane (the membrane G protein-coupled bile acid receptor TGR5) receptors as critical pharmacological targets for future therapeutic approaches. Encouraging data from recent experimental and phase-II studies tend to confirm that the FXR agonist obeticholic acid and the PPARα agonists bezafibrate and fenofibrate may be used as add-on therapies in PBC patients with inadequate responses to UDCA or even as alternative first-line agents. These results could mark the beginning of a new therapeutic era for PBC.

Farnesoid X receptor: from medicinal chemistry to clinical applications

The farnesoid X receptor (FXR) is a bile sensor that acts in coordination with other nuclear receptors to regulate essential steps in bile acid uptake, metabolism and excretion. In addition, FXR is an ancillary receptor involved in lipid and glucose homeostasis. Steroidal and non-steroidal FXR ligands are currently available. Both groups have shown limitations in the preclinical studies regarding absorption, metabolism, specificity of target and intrinsic toxicity. FXR ligands endowed with agonistic activity are under development for the treatment of cholestatic liver diseases, including primary biliary cirrhosis and metabolic disorders linked to insulin resistance. Despite the fact that results from preclinical models are encouraging, targeting FXR holds potential for side effects (i.e., impaired cholesterol disposal and cholestasis). Thus, results from FXR gene-ablated mice and mice administered an FXR antagonist support a role for FXR antagonists or modulators (i.e., FXR agonists that selectively activate specific subsets of FXR target genes in a tissue) or co-regulator-specific manner.

Liver transplantation in adults: Choosing the appropriate timing

Liver transplantation is indicated in patients with acute liver failure, decompensated cirrhosis, hepatocellular carcinoma and rare liver-based genetic defects that trigger damage of other organs. Early referral to a transplant center is crucial in acute liver failure due to the high mortality with medical therapy and its unpredictable evolution. Referral to a transplant center should be considered when at least one complication of cirrhosis occurs during its natural history. However, because of the shortage of organ donors and the short-term mortality after liver transplantation on one hand and the possibility of managing the complications of cirrhosis with other treatments on the other, patients are carefully selected by the transplant center to ensure that transplantation is indicated and that there are no medical, surgical and psychological contraindications. Patients approved for transplantation are placed on the transplant waiting list and prioritized according to disease severity. Thus, the appropriate timing of transplantation depends on recipient disease severity and, although this is still a matter of debate, also on donor quality. These two variables are known to determine the “transplant benefit” (i.e., when the expected patient survival is better with, than without, transplantation) and should guide donor allocation.