Autoreactivity against biliary tract antigens in primary biliary cirrhosis

Primary biliary cirrhosis and primary sclerosing cholangitis

Primary biliary cirrhosis and primary sclerosing cholangitis are the most common chronic cholestatic liver diseases in adults that lead to biliary cirrhosis and its inherent complications such as portal hypertension and liver failure. Although important advances in the understanding of the pathogenesis of these conditions have been accomplished in the last two decades, much work is needed to uncover the interaction of genetic and immunologic mechanisms involved in their pathogenesis. Ursodeoxycholic acid at dosage of 13 to 15 mg/kg/d is the only agent that can currently be recommended in the treatment of PBC. No medical therapy aimed at disrupting disease progression is available for patients with primary sclerosing cholangitis, although several agents with different properties are currently under evaluation. Liver transplantation is the treatment of choice for patients with primary biliary cirrhosis and primary sclerosing cholangitis with end-stage liver disease.

Differences in colonic disease activity in patients with ulcerative colitis with and without primary sclerosing cholangitis: a case control study

PURPOSE

A small group of patients with ulcerative colitis (UC) also suffer from primary sclerosing cholangitis (PSC). Genetic and immunologic differences exist between UC patients with and without concomitant PSC. Furthermore, UC patients with PSC are more prone to developing colonic dysplasia/aneuploidy compared with patients with UC only. Because colonic disease activity and treatment with sulfasalazine have been found to be of independent importance for development of colonic carcinoma in UC, this study aims to determine if differences exist concerning colonic disease activity in UC patients with and without PSC.

METHODS

Twenty-nine PSC patients with total colitis were matched to two UC patients with total colitis but without liver disease. Case records and questionnaires were used to gain information on pharmacologic treatment and disease activity.

RESULTS

Observation time was 20 (PSC group) and 23 years (UC only). Number of patients taking prophylactic treatment did not differ between groups. Patients with UC only had received treatment with systemic and local corticosteroids significantly more often than UC patients with PSC (P < 0.05 and P < 0.02). Patients with UC only were hospitalized because of colonic activity significantly more often (P < 0.02). Number of patients undergoing colectomy because of disease activity or number of patients with chronic continuous symptoms did not differ between the two groups.

CONCLUSION

UC in patients with PSC runs a milder course than UC in patients without this complication, although the number of patients taking prophylactic treatment was the same. If lower disease activity reflects differences in pathogenesis of UC in patients with PSC or if it can explain increased risk to develop colonic malignancy in patients with both PSC and UC needs further elucidation.

T cell autoreactivity against a 28 kD biliary protein (B1-p28) in primary biliary cirrhosis

BACKGROUND/AIMS

Cellular immune responses against biliary epithelial cells are important in understanding the pathogenesis of primary biliary cirrhosis. We previously reported a biliary antigen B1 which stimulated peripheral T lymphocytes of primary biliary cirrhosis as a possible, non-mitochondrial target of biliary epithelial cells. Further characterization of B1 was performed.

METHODS

To confirm localization of B1 in biliary epithelial cells, a mouse monoclonal antibody was raised against B1. As B1 could be separated into two main components by SDS-PAGE under reducing condition, these components were individually cut out from Western blots and converted into antigen-bearing particles for a proliferation assay to detect the antigenic component responsible for stimulating lymphocytes. The relation of this proliferation to HLA DR antigens was also analyzed.

RESULTS

Immunohistochemically, B1 was shown to be specifically expressed on biliary epithelial cells of human liver tissue. Of two components from B1 under reducing condition, prominent proliferation against B1-p28, a 28 kD component of B1 was detected in primary biliary cirrhosis. The reactivities were significantly higher than chronic liver diseases (p < 0.001) or normal controls (p < 0.001). Furthermore, high responders to B1-p28 were observed frequently in primary biliary cirrhosis patients with HLA DR8 (p < 0.02), which was susceptible to the development of primary biliary cirrhosis.

CONCLUSIONS

These data suggest B1-p28 expressed on biliary epithelial cells is a candidate for the target antigen of primary biliary cirrhosis in addition to mitochondrial autoantigens. Further characterization of B1-p28 may provide new insight into the autoimmune mechanisms of primary biliary cirrhosis.

Pathologic analysis of liver transplantation for primary biliary cirrhosis

A retrospective histopathologic review of all pathologic specimens from 394 adult liver transplant patients was undertaken with clinical correlation to determine if primary biliary cirrhosis has affected the posttransplant course compared to all other indications for liver transplantation and if recurrent primary biliary cirrhosis has occurred after liver transplantation. We also compared the histopathologic features seen in native livers with primary biliary cirrhosis to failed allografts with chronic rejection. One hundred six of the 394 adult patients transplanted during this time (1981 to July, 1986) fulfilled clinicopathologic criteria for a diagnosis of primary biliary cirrhosis. Neither the incidence nor any qualitative pathologic feature of histologically documented acute cellular rejection differentiated subjects transplanted for primary biliary cirrhosis vs. other diseases. No correlation between the titers of antimitochondrial antibody and the presence of posttransplant hepatic dysfunction based on liver enzyme profiles or the development of chronic rejection was seen in patients transplanted for primary biliary cirrhosis. Minor differences noted in the posttransplant course of primary biliary cirrhosis patients as compared to other conditions (higher incidence of chronic rejection as a cause of graft failure) was seen, but this did not significantly affect graft or patient survival. Recurrent primary biliary cirrhosis could not be diagnosed with certainty in any patient. A comparison of failed chronically rejected allografts vs. native hepatectomies obtained from patients with primary biliary cirrhosis revealed the presence of chronic obliterative vasculopathy, centrilobular cholestasis, and lack of granulomas, cirrhosis, cholangiolar proliferation, copper-associated protein deposition and Mallory's hyalin in specimens with chronic rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and statistical analyses of new and evolving therapies for primary biliary cirrhosis

Primary biliary cirrhosis is a chronic, progressive, cholestatic liver disease thought to be related to abnormalities in immune regulation. The disease is associated with granulomatous bile duct destruction, cholestasis, hepatic copper overloading and the development of hepatic fibrosis or cirrhosis or both. There have been numerous therapeutic trials evaluating immunosuppressive, antifibrotic and cupruretic agents. Prednisolone, D-penicillamine, azathioprine, colchicine and chlorambucil have been evaluated in controlled clinical trials, and biochemical improvement of liver function has been noted with all of the agents, except D-penicillamine. Improved survival has also been reported in patients treated long-term with azathioprine and colchicine. However, none of the therapeutic agents has been demonstrated to halt histologic progression of the disease or to induce a complete clinical, biochemical and histologic remission as has been reported in patients with autoimmune chronic active hepatitis treated with corticosteroids. Many of the trials did not use a double-blind design, failed to use the "intent to treat" rule or failed to define an objective time to analyze results. Many of the studies involved small numbers of patients with short-term follow-up and thus potentially were inadequate to appreciate drug effects that might be of clinical benefit. Currently, there is no totally effective therapy for primary biliary cirrhosis. We believe that well-designed clinical trials can provide important information to better understand this disease until a totally effective therapy is available. New clinical trials should use well-established methodologic guidelines in study design and well-accepted statistical standards in the analysis and interpretation of results.