Therapeutic role of bile acids and nuclear receptor agonists in fibrosing cholangiopathies

Intrahepatic cholangiocarcinoma: Morpho-molecular pathology, tumor reactive microenvironment, and malignant progression

Intrahepatic cholangiocarcinoma (iCCA) is a relatively rare, but highly lethal and biologically complex primary biliary epithelial cancer arising within liver. After hepatocellular carcinoma, iCCA is the second most common primary liver cancer, accounting for approximately 10-20% of all primary hepatic malignancies. Over the last 10-20 years, iCCA has become the focus of increasing concern largely due to its rising incidence and high mortality rates in various parts of the world, including the United States. The challenges posed by iCCA are daunting and despite recent progress in the standard of care and management options for iCCA, the prognosis for this cancer continues to be dismal. In an effort to provide a framework for advancing our understanding of iCCA malignant aggressiveness and therapy resistance, this review will highlight key etiological, biological, molecular, and microenvironmental factors hindering more effective management of this hepatobiliary cancer. Particular focus will be on critically reviewing the cell origins and morpho-molecular heterogeneity of iCCAs, providing mechanistic insights into high risk fibroinflammatory cholangiopathies associated with iCCA development, and notably discussing the deleterious role played by the tumor reactive desmoplastic stroma in regulating iCCA malignant progression, lymphangiogenesis, and tumor immunobiology.

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.

NorUDCA promotes degradation of α1-antitrypsin mutant Z protein by inducing autophagy through AMPK/ULK1 pathway

Alpha-1 Antitrypsin (α1AT) Deficiency is a genetic disease in which accumulation of α1AT mutant Z (α1ATZ) protein in the ER of hepatocytes causes chronic liver injury, liver fibrosis, and hepatocellular carcinoma. No effective medical therapy is currently available for the disease. We previously found that norUDCA improves the α1AT deficiency associated liver disease by promoting autophagic degradation of α1ATZ protein in liver in a mouse model of the disease. The current study unravels the novel underlying cellular mechanism by which norUDCA modulates autophagy. HTOZ cells, modified from HeLa Tet-Off cells by transfection with the resulting pTRE1-ATZ plasmid and expressing mutant Z proteins, were studied in these experiments. The role of norUDCA in inducing autophagy, autophagy-mediated degradation of α1ATZ and the role of AMPK in norUDCA-induced autophagy were examined in the current report. NorUDCA promoted disposal of α1ATZ via autophagy-mediated degradation of α1ATZ in HTOZ cells. Activation of AMPK was required for norUDCA-induced autophagy and α1ATZ degradation. Moreover, mTOR/ULK1 was involved in norUDCA-induced AMPK activation and autophagy in HTOZ cells. Our results provide novel mechanistic insights into the therapeutic action of norUDCA in promoting the clearance of α1ATZ in vitro and suggest a novel therapeutic approach for the treatment of α1ATZ deficiency disease and its associated liver diseases.

Patients with primary sclerosing cholangitis require more sedation during endoscopic retrograde cholangiography

Background and study aims Patients with primary sclerosing cholangitis (PSC) require repeated endoscopic retrograde cholangiography (ERC). Our aim was to evaluate whether patients with PSC require higher doses of sedation during ERC. Patients and methods We retrospectively analyzed all patients undergoing ERC from 2006 to 2013 who received conscious sedation with propofol and midazolam. The duration of the intervention and a potential progression of propofol consumption or intervention time by visit number were analyzed. Univariable and multivariable analyses were performed to identify independent factors which influence propofol consumption. Results A total of 2962 ERC procedures were performed in 1211 patients. Patients with PSC (n = 157) underwent 461 ERC procedures whereas patients without PSC (n = 1054) had 2501 ERC examinations. The total median propofol dose was 450 mg (290 - 630 mg) for patients with PSC and 300 mg (200 - 450 mg) for the non-PSC group (P < 0.05). The propofol consumption in patients with PSC was increased by a factor of 1.24 (P = 0.0071) independent of intervention time. Younger age (< 60.8 years) and duration of the intervention were associated with a higher need for sedation by factors of 1.21 and 1.71, respectively (P < 0.0001). The robustness of the results was tested in a sensitivity analysis which confirmed the results (P < 0.0001). Conclusions Patients with PSC may require higher doses of sedation for ERC compared to other patient groups independent of age and duration of ERC. The higher dosage of sedation has to be taken into account when using ERC to treat a patient with PSC.

Potential of nor-Ursodeoxycholic Acid in Cholestatic and Metabolic Disorders

24-nor-ursodeoxycholic acid (norUDCA) is a side-chain shortened derivate of ursodeoxycholic acid (UDCA). Since norUDCA is only ineffectively conjugated with glycine or taurine, it has specific physicochemical and therapeutic properties distinct from UDCA. Nonamidated norUDCA undergoes cholehepatic shunting enabling 'ductular targeting' and inducing a bicarbonate-rich hypercholeresis, with cholangioprotective effects. At the same time it has direct anti-inflammatory, antilipotoxic, anti fibrotic, and antiproliferative properties targeting various liver cell populations. norUDCA appears to be one of the most promising novel treatment approaches targeting the liver and the bile duct system at multifactorial and multicellular levels. This review article is a summary of a lecture given at the XXIII International Bile Acid Meeting (Falk Symposium 194) on 'Bile Acids as Signal Integrators and Metabolic Modulators' held in Freiburg, October 8-9, 2014, and summarizes the recent progress with norUDCA as a novel therapeutic approach in cholestatic and metabolic (liver) disorders.

Biomarkers for disease progression of primary sclerosing cholangitis

PURPOSE OF REVIEW

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown origin. There is no medical treatment of proven benefit on survival; once patients have progressed to end-stage liver disease, the only treatment option is liver transplantation.

RECENT FINDINGS

Over the last years, some progress has been made in identifying biomarkers of PSC disease progression. Categories that can be distinguished include clinical and biochemical biomarkers, histology, imaging, prognostic modelling and genetics. With this review, we summarize biomarkers for progression of PSC from these six categories, which have been studied to date.

SUMMARY

Biomarkers for the progression of PSC disease course can be used for several purposes. First of all, they can be implemented as surrogate endpoints for clinical trials. Second, biomarkers of disease progression form the basis of prognostic modelling, which is needed for proper patient counselling and management. Lastly, these biomarkers may yield a better understanding of PSC pathogenesis.

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.

The challenges of liver transplantation in children with primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) in children can progress to end-stage liver disease requiring liver transplantation. PSC poses many challenges beginning with evaluation and classification of ductal involvement and overlap syndromes, few options for medical management and unique risks in the post-transplant period. The construct that PSC may be an autoimmune disease is based on positive autoantibodies, association with inflammatory bowel disease, linkage to HLA type and overlap/autoimmune sclerosing cholangitis; however, PSC is not responsive to standard immunosuppression. Study of PSC and post-transplant outcomes in children may provide a unique background in which to study this challenging disease. This is particularly intriguing in the subset of patients diagnosed in the first decade of life, suggesting a strong link to predisposing genetic susceptibility and immune dysregulation. Long-term, multicenter effort is likely to be the only mechanism to study this rare disease in children and to improve outcomes in the future.

Role of natural killer cells and vitamin signaling in autoimmune liver disease

Natural killer (NK) cells are a major group of human hepatic lymphocytes. Their precursors undergo a maturation process that leads to the acquisition of their effecter functions to regulate the innate and acquired immune responses. With the changes in the expression of chemotactic receptors and adhesion molecules, NK cells migrate to the target organ, leading to the immune-related liver diseases. The discovery of the vitamin signaling and vitamin receptor expression in NK cell lineage, particularly the interaction with nuclear receptors, suggests a novel role for vitamin signaling in modulating immunological function and in the development or prevention of autoimmune diseases.