Primary biliary cholangitis (PBC), previously known as primary biliary "cirrhosis", is a rare autoimmune liver disease characterized by the hallmark autoantibodies to mitochondrial antigens and immune-mediated destruction of small bile duct epithelial cells leading to cholestasis and cirrhosis. Surprisingly, while immune modulators have not been effective in the treatment of PBC, supplementation with the hydrophilic bile acid (BA) ursodeoxycholic acid (UDCA) has been demonstrated to slow the disease progression. However, a significant minority of PBC patients do not have a complete response to UDCA and remain at risk of continued disease progression. Although the mechanisms of action are not well understood, UDCA provided proof of concept for BA therapy in PBC. Obeticholic acid (OCA), a novel derivative of the human BA chenodeoxycholic acid, is a potent agonist of the nuclear hormone receptor farnesoid X receptor, which regulates BA synthesis and transport. A series of clinical trials of OCA in PBC, primarily in combination with UDCA, have established that OCA leads to significant reductions in serum alkaline phosphatase that are predicted to lead to improved clinical outcomes, while dose-dependent pruritus has been the most common adverse effect. On the basis of these studies, OCA was given conditional approval by the US Food and Drug Administration with plans to establish the long-term clinical efficacy of OCA in patients with advanced PBC.

Primary sclerosing cholangitis (PSC) is a heterogeneous, idiopathic, inflammatory disorder frequently associated with inflammatory bowel diseases. PSC patients may be classified into several subphenotypes. Investigations of pediatric, nonwhite, and female PSC patients have revealed distinguishing features. The natural history of PSC is variable in progression with numerous possible clinical outcomes. PSC patients may suffer bacterial cholangitis, cholangiocarcinoma, or colorectal adenocarcinoma. Treatments focusing on bile acid therapy and immunosuppression have not proven beneficial. Interest in PSC and international collaboration has led to improved understanding of the heterogeneity and the genetic structure and introduced possible effective therapeutics.

Primary sclerosing cholangitis (PSC) is a rare, chronic, cholestatic liver disease of uncertain etiology characterized biochemically by cholestasis and histologically and cholangiographically by fibro-obliterative inflammation of the bile ducts. In a clinically significant proportion of patients, PSC progresses to cirrhosis, end-stage liver disease, and/or hepatobiliary cancer, though the disease course can be highly variable. Despite clinical trials of numerous pharmacotherapies over several decades, safe and effective medical therapy remains to be established. Liver transplantation is an option for select patients with severe complications of PSC, and its outcomes are generally favorable. Periodic surveillance testing for pre- as well as post-transplant patients is a cornerstone of preventive care and health maintenance. Here we provide an overview of PSC including its epidemiology, etiopathogenesis, clinical features, associated disorders, surveillance, and emerging potential therapies.

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are autoimmune cholestatic liver diseases that commonly result in the need for liver transplantation. The lack of an effective therapy for PSC remains a largely unmet need in hepatology, and although the majority of patients with PBC will have an adequate response to ursodeoxycholic acid and/or obeticholic acid, there is a need for treatment among patients who do not respond completely to these therapies. Investigations of statins, fibrates, and other peroxisome proliferator-activated receptor (PPAR) agonists suggest clinical benefit with some of these agents. Statins have recently been suggested to improve outcomes in patients with PSC but have not demonstrated benefit in patients with PBC, whereas fibrates and newer PPAR agonists appear to improve biochemical markers linked to better clinical outcomes in patients with PBC. Further research is needed to fully understand the clinical efficacy of these agents in the treatment of PBC and PSC.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease histologically characterized by the presence of intrahepatic and/or extrahepatic biliary duct concentric, obliterative fibrosis, eventually leading to cirrhosis. Approximately 75% of patients with PSC have inflammatory bowel disease. The male predominance of PSC, the lack of a defined, pathogenic autoantigen, and the potential role of the innate immune system suggest that it may be due to dysregulation of immunity rather than a classic autoimmune disease. However, PSC is associated with several classic autoimmune diseases, and the strongest genetic link to PSC identified to date is with the human leukocyte antigen DRB01*03 haplotype. The precise immunopathogenesis of PSC is largely unknown but likely involves activation of the innate immune system by bacterial components delivered to the liver via the portal vein. Induction of adhesion molecules and chemokines leads to the recruitment of intestinal lymphocytes. Bile duct injury results from the sustained inflammation and production of inflammatory cytokines. Biliary strictures may cause further damage as a result of bile stasis and recurrent secondary bacterial cholangitis. Currently, there is no effective therapy for PSC and developing a rational therapeutic strategy demands a better understanding of the disease.

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.

Primary biliary cholangitis (PBC) is an autoimmune inflammatory liver disease of the interlobular bile ducts that can lead to cirrhosis and liver failure. Until recently, the only effective treatment was ursodeoxycholic acid (UDCA). However, up to 40% of PBC patients have an inadequate response to UDCA and may continue to have disease progression. Several models have been developed, including the UK-PBC and GLOBE scores, to assist in identifying patients who may benefit from second-line therapies, such as the farnesoid X receptor (FXR) agonist obeticholic acid (OCA). The addition of OCA can significantly improve serum alkaline phosphatase and total bilirubin, which are strong surrogate markers of clinical outcomes in PBC. Other alternatives, including the peroxisome proliferator-activated receptor (PPAR)-α agonists fenofibrate and bezafibrate, may also improve liver biochemistries in PBC patients with an inadequate response to UDCA, but further study is needed to demonstrate their safety and long-term efficacy. Other novel agents, including those targeting the FXR pathway and PPAR-δ agonists, have shown promising results and may alter the therapeutic landscape of PBC in the near future. For now, OCA remains the only approved second-line agent for PBC patients with an inadequate response to UDCA while results of long-term studies of its safety and clinical benefit are awaited.

The thymus-specific serine protease Prss16 is highly expressed by the epithelial cells in the thymic cortex. It has been suggested to play an important role in the positive selection of T cells through the antigen presention pathway of the cortical antigen presenting cells. Recently, the gene encoding Prss16 has been linked to insulin dependent diabetes mellitus (IDDM) susceptibility independent of HLA-DR3 suggesting the Prss16 may be involved in the development of autoimmune disease. Due to the similarities of the gene structure and expression pattern between the human and mouse genes, we compared Prss16 between non-obese diabetic (NOD) and non-obese non-diabetic (NON) mice. Analysis of the Prss16 coding region failed to identify any differences in sequence. Northern analysis and semi-quantitative reverse transcriptase polymerase chain reaction showed that the mRNA was equal in size and abundance in the two strains. In situ hybridization showed similar patterns of staining. Therefore, our data suggests that there is no significant different in the gene structure, transcription level, and expression pattern of Prss16 gene between NOD and NON mice.

Purpose of review

Primary sclerosing cholangitis (PSC) is a rare, idiopathic biliary disease often with an insidious onset, variable disease course, and premature death related to benign and malignant PSC-related sequelae. This review aims to discuss the epidemiology, clinical variants, and natural history of PSC, incorporating data from recent population-based studies.

Recent findings

PSC naturally leads to cirrhosis, cholangiocarcinoma, other hepatobiliary malignancies, dominant strictures, hepatic osteodystrophy, and bacterial cholangitis. The incidence of PSC appears to be increasing, the reasons for which are unclear. The time from diagnosis to liver transplant appears to be longer in more recent studies compared with earlier studies, suggesting a better overall prognosis than previously believed. In addition, with an increasing number of patients undergoing liver transplantation for PSC, the frequency of death because of liver failure has decreased, whereas cancer-related deaths have increased among patients with PSC.

Summary

PSC is a heterogeneous disease with a variety of clinical outcomes, both fatal and nonfatal. The progression of liver fibrosis in an individual patient is difficult to predict and may vary from a relatively benign, nonprogressive form to a rapidly progressive form with the need for liver transplantation.

http://aasldpubs.onlinelibrary.wiley.com/hub/journal/10.1002/(ISSN)2046-2484/video/15-3-reading-louie a video presentation of this article.