Primary sclerosing cholangitis - What is the difference between east and west?

Global incidence, prevalence and features of primary sclerosing cholangitis: A systematic review and meta-analysis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is an idiopathic, cholestatic liver disease with a diverse range of clinical manifestations. Inter-regional data on PSC are variable, but its global geoepidemiology has not been well-studied. We aimed to examine the worldwide incidence, prevalence and features of PSC and PSC-inflammatory bowel disease (PSC-IBD).

METHODS

A systematic search of multiple databases was conducted to identify all original, full-text studies until December 2020 with data regarding the incidence rate (IR) and/or prevalence of PSC. Outcomes were PSC IR, prevalence, features and IBD concurrence. Additionally, a meta-analysis of PSC IR was performed. The study was registered in PROSPERO (CRD42021224550).

RESULTS

Of the 1003 studies identified, 17 studies spanning three continents were included. PSC IR was 0.60 per 100 000 person-years (PY) (95% confidence interval: 0.37-0.88 per 100 000 PY). In pooled subgroup analysis for studies conducted in Europe and North America, PSC IR was 0.62 and 0.53 per 100 000 PY, respectively. PSC prevalence ranged 0-31.7 per 100 000 persons, with notable inter-regional differences. Mean age at PSC diagnosis was bimodally distributed, with relative peaks at 15 and 35 years. Mean concurrence of IBD with PSC was 50%, with 76% having ulcerative colitis, 17% Crohn's disease and 8% indeterminate/unspecified IBD.

CONCLUSION

While considerable heterogeneity exists in the geoepidemiology of PSC, overall, the classical dogmata of male predilection, bimodal distribution of mean age and high PSC-IBD concurrence appear to hold true. Despite a seemingly stable IR over time, further studies are needed to better understand the geoepidemiology of PSC.

Efficacy of Ustekinumab Against Spondyloarthritis Associated with Crohn's Disease: A Case Report and Review of the Literature

Spondyloarthritis (SpA) is a known extraintestinal complication in inflammatory bowel disease (IBD). However, since the prevalence of SpA is lower in Japan than in Europe, some patients may be inaccurately diagnosed and treated. Although non-steroidal anti-inflammatory drugs (NSAIDs) remain the mainstay treatment for IBD-related SpA, anti-tumor necrosis factor-α antibody and ustekinumab have demonstrated efficacy in patients with SpA refractory to NSAIDs. We report here a case of Crohn's disease with SpA, as an extraintestinal manifestation, in which ustekinumab proved extremely effective, not only for alleviating the arthritis but also against skin manifestations and scleritis. Only a few studies have documented the therapeutic effects of ustekinumab against SpA associated with IBD; therefore, its efficacy remains unclear.

Extraintestinal manifestations in inflammatory bowel disease - epidemiology, genetics, and pathogenesis

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder, primarily of, but not restricted to the gut. Extraintestinal manifestations (EIMs) are frequently observed and involve the joints, eyes, hepatobiliary tract, and skin. Areas covered: In this review, we discuss classical EIM focusing on epidemiology, genetics, and pathogenesis, highlighting recent advances in the understanding of EIM. We further discuss treatment-induced immunological phenomena, which are increasingly recognized and might challenge IBD-treating physicians in the era of biological treatment. Expert opinion: EIM considerably contributes to morbidity and mortality. Genetic studies have revealed a common genetic background between EIM and IBD and among specific EIM. Identified protein interactions have been shown to cluster in shared biological pathways. However - despite these recent advances - pathogenesis of EIM is at best partially understood. Several pathogenic mechanisms have been proposed such as upregulation of tumor necrosis factor, aberrant lymphocyte homing, and cross-reactive antigen presentation. It still remains unclear whether EIM is a direct result of the inflammatory process in the gut or rather a consequence of a shared genetic background leading to dysfunctional immune responses to environmental stimuli. Exploration and understanding of EIM genetics and pathophysiology will pave the road for better and more efficacious treatment options in the future.

Specific Features of Patients With Inflammatory Bowel Disease and Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is a chronic and progressive disease of the biliary tract. PSC is strongly associated with inflammatory bowel disease (IBD), mainly with ulcerative colitis, and most PSC patients have underlying IBD. The pathophysiological interactions between IBD and PSC are unclear, although it seems that the patients with IBD and PSC have a distinct phenotype. IBD with coexisting PSC is more extensive and is characterized by milder activity compared to IBD alone. The coexistence of PSC increases the risk for colorectal cancer in IBD patients and lifelong annual surveillance colonoscopy is recommended. Also, liver transplantation (LT) for PSC may affect the course of IBD. In addition, the management of IBD after LT includes many specific problems. On the other hand, the effect of IBD on the natural history of PSC appears to be milder. However, IBD may increase the risk of postsurgical complications after LT and is a risk factor for recurrent PSC after LT. Overall, the coexistence of IBD with PSC changes the management, natural history and prognosis of both diseases.

Inflammatory Bowel Disease and Primary Sclerosing Cholangitis: A Review of the Phenotype and Associated Specific Features

Primary sclerosing cholangitis (PSC) is a chronic, progressive cholestatic disease that is associated with inflammatory bowel disease (IBD) in approximately 70% of cases. Although the pathogenesis is still unknown for both diseases, there is increasing evidence to indicate that they share a common underlying predisposition. Herein, we review the epidemiology, diagnosis, disease pathogenesis, and specific clinical features of the PSC-IBD phenotype. Patients with PSC-IBD have a distinct IBD phenotype with an increased incidence of pancolitis, backwash ileitis, and rectal sparing. Despite often having extensive colonic involvement, these patients present with mild intestinal symptoms or are even asymptomatic, which can delay the diagnosis of IBD. Although the IBD phenotype has been well characterized in PSC patients, the natural history and disease behavior of PSC in PSC-IBD patients is less well defined. There is conflicting evidence regarding the course of IBD in PSC-IBD patients who receive liver transplantation and their risk of recurrent PSC. IBD may also be associated with an increased risk of cholangiocarcinoma in PSC patients. Overall, the PSC-IBD population has an increased risk of developing colorectal neoplasia compared to the conventional IBD population. Lifelong annual surveillance colonoscopy is currently recommended.

Clinical guidelines for primary sclerosing cholangitis 2017

BACKGROUND

Primary sclerosing cholangitis (PSC) is relatively rare disease and pathogenesis and methods of treatments were still not established. Then, we had conducted the making clinical guidelines to manage patients with PSC based on the literature review and expert opinions. These clinical guidelines were made for the medical doctors on the management of PSC, except child case of PSC.

METHODS

We had employed modified Delphi method. The production committee decided guidelines, strength of recommendations and evidence level after reviewed literatures systematically, and The Expert panel evaluated those. The Scientific Committee of the Japan Biliary Association (JBA) evaluated revised guidelines, and the Public comments were collected on web site of JBA.

RESULTS

We had made 16 guidelines about epidemiology/pathophysiology, diagnostics, therapy and prognosis. Also, we had made both diagnostic and therapeutic flow chart.

CONCLUSIONS

We hope that these guidelines will contribute to the improvement and development of the medical care of PSC.

Efficacy of ustekinumab against infliximab-induced psoriasis and arthritis associated with Crohn's disease

Anti-TNFα drugs have been shown to be effective for maintaining stable remission in patients with Crohn's disease. However, some problems have been identified during clinical use of this class of drugs, such as secondary treatment failure, in which the drugs become progressively less effective with time, and the development of paradoxical reactions such as psoriatic skin symptoms. Thus, while anti-TNFα drugs are used to treat psoriasis, they can sometimes also cause paradoxical psoriasis, characterized by the appearance of psoriasis-like eruptions, which has recently begun to attract attention. Furthermore, inflammatory bowel disease is not only associated with intestinal lesions, but also with a variety of extraintestinal manifestations, of which arthritis is relatively common. We encountered a case of Crohn's disease with arthritis, as an extraintestinal manifestation, and paradoxical psoriasis caused by infliximab treatment, in which ustekinumab proved extremely effective, not only for alleviating the arthritis, but also against the skin manifestations. To the best of our knowledge, this is the first reported case of the efficacy of ustekinumab against paradoxical psoriasis and arthritis in a patient with Crohn's disease.

Primary sclerosing cholangitis: A review and update

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.

Clinical Course of Ulcerative Colitis After Liver Transplantation in Patients with Concomitant Primary Sclerosing Cholangitis and Ulcerative Colitis

BACKGROUND

The natural history of ulcerative colitis (UC) after liver transplantation (LT) for primary sclerosing cholangitis (PSC) remains ill defined. This study aimed to evaluate the course of UC after LT for PSC.

METHODS

The course of UC, including the clinical colitis severity index, was evaluated in patients with concomitant PSC and UC who received LT for PSC-induced end-stage liver disease. A total of 167 (55.4%) patients with PSC had concurrent inflammatory bowel disease (IBD). Of 159 cases of IBD that started before LT, 152 (95.5%) had UC and 7 (4.5%) had Crohn's disease.

RESULTS

The mean duration of patient follow-up after LT was 47.7 ± 33.5 months. The simple clinical colitis activity index scores after LT showed no change in 15.8% of patients, decreased in 78.3%, and increased in 5.9%. Seventy-one (46.7%) patients required no change in their specific UC treatment after LT, whereas 12 (7.9%) had to use more aggressive treatments after LT. In 69 (45.4%) patients, treatment could be tapered although not discontinued. Multiple logistic regression analysis demonstrated that the duration of LT (odds ratio = 1.02; 95% confidence interval, 1.00-1.05, P = 0.03) was significantly associated with aggravation in the clinical course of UC after LT. Posttransplant cyclosporine exposure (odds ratio = 0.14; 95% confidence interval, 0.015-0.79, P = 0.028) and pretransplant body weight (odds ratio = 0.81; 95% confidence interval, 0.71-0.93, P = 0.003) demonstrated a protective effect.

CONCLUSIONS

Although the clinical course of UC remains unchanged or even improves in the majority of patients after LT, some may experience an aggressive course. The type of immunosuppression after transplantation can affect UC activity after LT. Cyclosporine may have some protective effects post-LT.

Prevalence of inflammatory bowel disease among patients with primary sclerosing cholangitis in Iran

BACKGROUND AND STUDY AIMS

In Iran, the epidemiology of primary sclerosing cholangitis (PSC) and its association with inflammatory bowel disease (IBD) have not been studied thoroughly. This study investigates the epidemiology and prevalence of IBD among patients with PSC.

PATIENTS AND METHODS

A retrospective study of 154 patients with PSC was conducted. The demographic and clinical data were collected, and the variables were analysed in the following two patient groups: patients with both PSC and IBD, and patients with PSC and without IBD.

RESULTS

A total of 154 patients with a mean age of 40.3years (range 20-81years) were included, of whom 57 (37%) were female and 97 (63%) male. Ninety-six patients (62.3%) were diagnosed with IBD, 92 (59.7%) with ulcerative colitis, and four (2.6%) with Crohn's disease. In this study, elevated alkaline phosphatase levels were found in 90.8% of patients. The intra-hepatic duct (IHD) and extrahepatic duct (EHD) were involved in 70.5% of patients, isolated intrahepatic bile duct in 24.4%, and isolated extrahepatic duct in 3.8%. Small-duct PSC (normal results of imaging and PSC proved by histology of liver biopsy) was observed only in 1.3% of patients.

CONCLUSION

PSC has become increasingly diagnosed in Iran. This is possibly because of better diagnostics and the increasing prevalence of IBD in this country. For diagnosing PSC and identifying the presence of IHD strictures, the results of both magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP) showed good interobserver agreement, but the ERCP results could be used to evaluate the presence and severity of EHD strictures.

Frequency and risk factors of primary sclerosing cholangitis among patients with inflammatory bowel disease in North-East of Iran

AIM

To identify primary sclerosing cholangitis (PSC) predisposing factors in order to prevent inflammatory bowel disease (IBD) progression to PSC.

BACKGROUND

IBD is commonly associated with PSC and there is no effective therapy for PSC except for liver transplantation.

PATIENTS AND METHODS

This retrospective study was conducted on 447 IBD patients from IBD Clinics of Ghaem and Emam Reza Hospitals. Data were collected by interview and through a review of the patients' medical records. Patients were divided into two groups: those with IBD and PSC (IBD-PSC) and those without PSC. Variables were compared between two groups and those with statistically significant differences in IBD-PSC group were considered as predictive factors for the development of PSC.

RESULTS

The frequency of PSC in IBDs was 4.3% and all were ulcerative colitis. The mean age of patients with PSC was 39.1±11.33 years. The male to female proportion in PSCs was 3.8:1 and in IBDs was 0.9:1. There were statistically significant associations between PSC and gender, IBD duration and UC extension, mucocutaneous involvement, oral contraceptive pills (OCP) consumption, history of surgery and history of PSC in the first- degree relatives.

CONCLUSION

PSC frequency among IBD patients in North-East of Iran was 4.3%. It is recommended to limit OCP consumption in IBD patients. Identification and modification of probable predisposing risk factors, as well as early diagnosis of PSC are necessary.

A morphological and immunohistochemical study of the effects of prednisolone or ursodeoxycholic acid on liver histology in feline lymphocytic cholangitis

Feline lymphocytic cholangitis (LC) has been commonly treated with prednisolone, and more recently with ursodeoxycholic acid (UDCA). Previously, we found that prednisolone treatment resulted in a statistically longer survival time than treatment with UDCA. In order to explain this difference, we compared the effects of prednisolone and UDCA treatment on hepatic tissue by evaluating consecutive liver biopsies. Archival serial biopsy materials from cats with LC treated with prednisolone (n = 5) or UDCA (n = 4) were evaluated. We employed haematoxylin and eosin staining to evaluate inflammation, and reticulin staining for fibrosis. Immunohistochemical stainings for Ki-67, K19 (Cytokeratin 19) and α-smooth muscle actin were used to evaluate cell type-specific proliferation and activation of hepatic stellate cells. Inflammation decreased more in the group treated with prednisolone, while the number of cholangiocytes, progenitor cells and fibroblasts did not differ between the treatment groups. Additionally, no difference was found for the amount of fibrosis in both treatment groups.

Advances and controversies in the pathogenesis and management of primary sclerosing cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a chronic immune-mediated liver disease that results in end-stage liver disease requiring liver transplantation. PSC is closely associated with inflammatory bowel disease (IBD) with 70% of patients with PSC also suffering from IBD.

SOURCES OF DATA

Data for this review were obtained from PubMed.

AREAS OF AGREEMENT

Historical and genome-wide association studies have established a strong human leukocyte antigen (HLA) linkage to PSC and defined specific haplotypes associated with enhanced PSC risk. Fifteen non-HLA loci have been defined in PSC.

AREAS OF CONTROVERSY

The biological role of risk loci in PSC and their place in PSC pathogenesis remain speculative but suggest significant interactions with the host microbiome and therapeutic opportunities.

GROWING POINTS

Genetics provides a platform to systematically target emerging therapies in PSC.

AREAS TIMELY FOR DEVELOPING RESEARCH

Linking PSC genotypes with biology and disease phenotypes paves the way for a personalized medicine approach to manage PSC.

Association between serum IgE level and adverse clinical endpoints in primary sclerosing cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is an idiopathic hepatobiliary disorder associated with an increased risk for cholangiocarcinoma (CCA) and a median survival time of 12 years. Reliable predictors of CCA and other major adverse events in PSC are currently lacking. Recently, serum IgE was found to be associated with CCA in a Japanese cohort of PSC patients. Our aim in this study was to determine whether IgE levels predict time to CCA, liver transplantation, or death in a Western (USA-based) cohort of PSC patients.

MATERIAL AND METHODS

Thirty-eight patients with PSC and IgE levels were identified and categorized into low or high IgE groups based on the sample median. Groups were compared with respect to clinical characteristics and adverse endpoint-free survival, and the association between IgE and endpoints was assessed with multivariate proportional-hazards models.

RESULTS

The median sample age at PSC diagnosis was 41 years, and median serum IgE level was 47.6 kU/L. Low and high IgE groups differed significantly only with respect to IgG subclasses, which were higher among the latter (p < 0.05). There were no significant differences in composite endpoint-free (p = 0.83) or CCA-free survival (p = 0.20). In multivariate analyses, only Mayo PSC risk score and MELD score were significant predictors of endpoint-free survival (p < 0.05).

CONCLUSIONS

Serum IgE level is associated with several IgG subclass levels but not time to CCA, liver transplantation, or death among PSC patients in a USA-based cohort. While Mayo PSC risk score and MELD score can predict these outcomes, more specific predictors of CCA are needed.

Inflammatory bowel disease of primary sclerosing cholangitis: A distinct entity?

This is a review of the characteristic findings of inflammatory bowel disease (IBD) associated with primary sclerosing cholangitis (PSC) and their usefulness in the diagnosis of sclerosing cholangitis. PSC is a chronic inflammatory disease characterized by idiopathic fibrous obstruction and is frequently associated with IBD. IBD-associated with PSC (PSC-IBD) shows an increased incidence of pancolitis, mild symptoms, and colorectal malignancy. Although an increased incidence of pancolitis is a characteristic finding, some cases are endoscopically diagnosed as right-sided ulcerative colitis. Pathological studies have revealed that inflammation occurs more frequently in the right colon than the left colon. The frequency of rectal sparing and backwash ileitis should be investigated in a future study based on the same definition. The cholangiographic findings of immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) are similar to those of PSC. The rare association between IBD and IgG4-SC and the unique characteristics of PSC-IBD are useful findings for distinguishing PSC from IgG4-SC.

Non-IBD immunological diseases are a risk factor for reduced survival in PSC

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease. It is known to be associated with immunological diseases (IDs), such as inflammatory bowel disease (IBD) and autoimmune hepatitis (AIH).

AIM

We evaluated the presence of IDs besides IBD and AIH in a cohort of PSC patients, and its association with clinical outcome.

METHODS

This is a prospective cohort study of 195 PSC patients that were evaluated over the period 1987-2010 in our tertiary care centre. The presence of ID was determined using a retrospective chart review. IDs were subclassified into autoimmune disease (AID) and immune-mediated inflammatory disease (IMID), according to current guidelines.

RESULTS

Twenty-seven of 195 (13.8%) PSC patients had at least one additional ID other than IBD (70%) or AIH (5%). The most frequent AIDs were autoimmune thyroiditis (2.6%) and diabetes mellitus type 1 (2.1%). The most frequent IMIDs were psoriasis (3.6%) and sarcoidosis (2.1%). After more than 20 years of follow-up, concomitant IDs represent an independent risk factor for reduced transplantation-free survival in patients with PSC (mean: 8.9 years vs. 16.3 years, P = 0.012). Further subgroup analysis revealed a significantly reduced survival especially in patients with concomitant IMID (P = 0.017).

CONCLUSION

Patients with concomitant IDs, especially IMID, are a clinically important subgroup of PSC patients. This significant phenotype warrants further genetic and immunological studies.

Epidemiology and clinical course of Crohn's disease: Results from observational studies

The authors review the clinical outcome in patients with Crohn’s disease (CD) based on studies describing the natural course of the disease. Population-based studies have demonstrated that the incidence rates and prevalence rates for CD have increased since the mid-1970s. The authors search for English language articles from 1980 until 2011. Geographical variations, incidence, prevalence, smoking habits, sex, mortality and medications are investigated. An increasing incidence and prevalence of CD have been found over the last three decades. The disease seems to be most common in northern Europe and North America, but is probably increasing also in Asia and Africa. Smoking is associated with an increased risk of developing CD. Age < 40 at diagnosis, penetrating/stricturing complications, need for systemic steroids, and disease location in terminal ileum are factors associated with higher relapse rates. A slight predominance of women diagnosed with CD has been found. Ileocecal resection is the most commonly performed surgical procedure, and within the first five years after the diagnosis about one third of the patients have had intestinal surgery. Smoking is associated with a worse clinical course and with increased risk of flare-ups. In most studies the overall mortality is comparable to the background population. To date, the most effective treatment options in acute flares are glucocorticosteroids and tumor necrosis factor (TNF)-α- blockers. Azathioprine/methotrexate and TNF-α-blockers are effective in maintaining remission.

Recurrence and rejection in liver transplantation for primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic progressive inflammatory disease affecting the bile ducts, leading to fibrosis and eventually cirrhosis in most patients. Its etiology is unknown and so far no effective medical therapy is available. Liver transplantation (LTX) is the only curative treatment and at present PSC is the main indication for LTX in the Scandinavian countries. Close to half of the PSC patients experience one or more episodes of acute cellular rejection (ACR) following transplantation and approximately 1/5 of the transplanted patients develop recurrent disease in the graft. In addition, some reports indicate that ACR early after LTX for PSC can influence the risk for recurrent disease. For these important post-transplantation entities affecting PSC patients, we have reviewed the current literature on epidemiology, pathogenesis, treatment and the possible influence of rejection on the risk of recurrent disease in the allograft.

Inflammatory bowel disease is associated with poor outcomes of patients with primary sclerosing cholangitis

BACKGROUND & AIMS

Little is known about the exact etiology of primary sclerosing cholangitis (PSC); epidemiologic data are scarce. We performed a population-based epidemiologic study of PSC in Canterbury, New Zealand.

METHODS

By using multiple case-finding methods, we searched public and private adult and pediatric outpatient clinics, hospital discharge summaries, and radiology and pathology reports to identify all cases of PSC in the region. Cases were included if PSC was identified by endoscopic retrograde cholangiography, magnetic resonance cholangiography, or liver biopsy analysis (n = 79).

RESULTS

The incidence of PSC in 2008 was 1.6 per 100,000 persons (95% confidence interval [CI], 0.5-2.7). The point prevalence on December 31, 2008, was 11.7 per 100,000 persons (95% CI, 8.7-14.8). The mean and median ages at diagnosis were 50 years (95% CI, 46-53 years) and 49 years (range, 17-80 years), respectively. Patients who had inflammatory bowel disease (IBD) presented with PSC earlier than those without IBD (P = .003), were more likely to develop serious malignant complications (P = .017), and were more likely to require liver transplantation or die (P = .03).

CONCLUSIONS

In a population-based epidemiology study of PSC in Canterbury, New Zealand, we observed large differences between PSC patients with or without concurrent IBD in age at diagnosis, development of cancer, mortality, and requirement for liver transplantation. IBD therefore affects outcomes of patients with PSC, an important observation that requires further study.

Successful low-dose azathioprine for myasthenia gravis despite hepatopathy from primary sclerosing cholangitis: a case report

INTRODUCTION

Although myasthenia gravis is frequently associated with other disorders, it has not been reported together with primary sclerosing cholangitis, complicating the administration of liver-toxic immunosuppressive therapy.

CASE PRESENTATION

A 73-year-old Caucasian woman with a history of arterial hypertension, thyroid dysfunction, glaucoma, right-sided ptosis and later generalized weakness, was diagnosed with myasthenia gravis. Additionally, primary sclerosing cholangitis was detected, initially prohibiting the administration of immunosuppressants. Despite treatment with steroids and pyridostigmine she repeatedly experienced myasthenic crises. After the fifth crisis and after antibody titers had reached levels > 100 nmol/L during two years of follow-up, it was decided to restart azathioprine. Interestingly, low-dose azathioprine (1.5 mg/kg/day) was well tolerated, had a positive clinical and immunological effect and did not worsen primary sclerosing cholangitis.

CONCLUSION

Myasthenia gravis may occur together with primary sclerosing cholangitis in the same patient. Mild immunosuppression with azathioprine is feasible and effective in such a patient, without worsening myasthenia gravis or primary sclerosing cholangitis.

The immunobiology of primary sclerosing cholangitis

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.