Search

Unlabelled: The role of the cytokine, macrophage migration inhibitory factor (MIF), and its receptor, CD74, was assessed in autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC). Two MIF promoter polymorphisms, a functional -794 CATT5-8 microsatellite repeat (rs5844572) and a -173 G/C single-nucleotide polymorphism (rs755622), were analyzed in DNA samples from over 500 patients with AIH, PBC, and controls. We found a higher frequency of the proinflammatory and high-expression -794 CATT7 allele in AIH, compared to PBC, whereas lower frequency was found in PBC, compared to both AIH and healthy controls. MIF and soluble MIF receptor (CD74) were measured by enzyme-linked immunosorbent assay in 165 serum samples of AIH, PBC, and controls. Circulating serum and hepatic MIF expression was elevated in patients with AIH and PBC versus healthy controls. We also identified a truncated circulating form of the MIF receptor, CD74, that is released from hepatic stellate cells and that binds MIF, neutralizing its signal transduction activity. Significantly higher levels of CD74 were found in patients with PBC versus AIH and controls., Conclusions: These data suggest a distinct genetic and immunopathogenic basis for AIH and PBC at the MIF locus. Circulating MIF and MIF receptor profiles distinguish PBC from the more inflammatory phenotype of AIH and may play a role in pathogenesis and as biomarkers of these diseases., (© 2013 by the American Association for the Study of Liver Diseases.)

Unlabelled: Antimitochondrial antibodies (AMAs) directed against the lipoyl domain of the E2 subunit of pyruvate dehydrogenase (PDC-E2) are detected in 95% of patients with primary biliary cirrhosis (PBC) and are present before the onset of clinical disease. The recent demonstration that AMAs recognize xenobiotic modified PDC-E2 with higher titers than native PDC-E2 raises the possibility that the earliest events involved in loss of tolerance are related to xenobiotic modification. We hypothesized that reactivity to such xenobiotics would be predominantly immunoglobulin M (IgM) and using sera from a large cohort of PBC patients and controls (n = 516), we examined in detail sera reactivity against either 6,8-bis(acetylthio) octanoic acid (SAc)-conjugated bovine serum albumin (BSA), recombinant PDC-E2 (rPDC-E2) or BSA alone. Further, we also defined the relative specificity to the SAc moiety using inhibition enzyme-linked immunosorbent assay (ELISA); SAc conjugate and rPDC-E2-specific affinity-purified antibodies were also examined for antigen specificity, isotype, and crossreactivity. Reactivity to SAc conjugates is predominantly IgM; such reactivity reflects a footprint of previous xenobiotic exposure. Indeed, this observation is supported by both direct binding, crossreactivity, and inhibition studies. In both early and late-stage PBC, the predominant Ig isotype to SAc is IgM, with titers higher with advanced stage disease. We also note that there was a higher level of IgM reactivity to SAc than to rPDC-E2 in early-stage versus late-stage PBC. Interestingly, this finding is particularly significant in light of the structural similarity between SAc and the reduced form of lipoic acid, a step which is similar to the normal physiological oxidation of lipoic acid., Conclusion: Specific modifications of the disulfide bond within the lipoic-acid-conjugated PDC-E2 moiety, i.e., by an electrophilic agent renders PDC-E2 immunogenic in a genetically susceptible host., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Background & Aims: The combination of ursodeoxycholic acid (UDCA), colchicine, and methotrexate (MTX) is effective therapy for a subset of patients with primary biliary cirrhosis (PBC) who do not respond to UDCA. However, the durability of the response is unclear. We investigated whether the response to combination therapy was durable., Methods: We followed, for 10 additional years (range 9-13 years), 29 patients with PBC who had been treated with the combination of UDCA and MTX or UDCA and colchicine in a randomized controlled trial that began in 1988 and lasted 10 years., Results: Of the 11 patients given MTX plus UDCA, 9 were still alive and well, whereas 2 died from causes unrelated to liver disease at the ages of 79 and 70. Of the 18 patients given the combination of colchicine and UDCA, 12 were alive and well 20 years after the trial ended. Three had progressive liver disease; 2 of these had liver transplantation and 1 died of pneumonia. Three died of unrelated causes at the ages of 73, 76, and 76 years, respectively., Conclusions: Treatment with the combination of UDCA and MTX or UDCA and colchicine led to sustained clinical remission in a subset of patients with PBC. The response to the combination of UDCA and MTX appeared to be more durable than to UDCA and colchicine., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: The prevalence of and the most appropriate way to diagnose the primary biliary cirrhosis (PBC)-chronic autoimmune hepatitis (AIH) overlap syndrome are uncertain. We investigated the prevalence of PBC and AIH and their level of overlap at a tertiary referral center, along with clinical, biochemical, and serologic characteristics., Methods: We reviewed data from all patients with PBC (n = 609) and/or AIH (n = 15) examined at the Tufts Medical Center (Boston, MA) from January 1, 2000, to June 20, 2006. PBC was diagnosed based on 2 of the following 3 results: 6 months of positive results in tests for cholestatic liver enzymes, a positive result in a test for antimitochondrial antibodies, or a liver biopsy that indicated PBC. AIH was defined as an alanine aminotransferase level of 200 U/L or greater (≥ 5-fold above normal), a liver biopsy that indicated severe interface hepatitis, and levels of immunoglobulin G 2-fold or greater than that of normal., Results: Only 6 patients with PBC (1%) met the Paris criteria for the overlap syndrome. If we included 9 patients with PBC who did not meet the Paris criteria, but had results from liver enzyme tests and liver biopsy analyses that indicated improvement after treatment with prednisone, the prevalence was 15 (2.8%). This is at the low end of previously reported prevalence values for overlap of PBC and AIH (2%-20%)., Conclusions: The prevalence of the PBC-AIH overlap syndrome varies among medical centers. We propose that if the definition of PBC-AIH overlap syndrome be modified to include patients with unequivocal responses to prednisone despite not meeting the Paris criteria, this would improve treatment of patients., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Approximately 35% of PBC patients have progressive disease despite treatment with UDCA., Aims: We offered treatment with methotrexate and colchicine to PBC patients who had not responded fully to UDCA, after at least 1 year of treatment., Methods: A total of 91 PBC patients failed to respond adequately to UDCA, defined as patients whose liver biopsies showed persistent interface hepatitis and whose serum alkaline phosphatase levels remained more than 50% above normal after at least 12 months on UDCA. We added colchicine (0.6 mg orally twice daily) for 6 months. If there was no decrease in alkaline phosphatase, methotrexate (0.25 mg/kg lean body weight orally per week) was added. Liver biopsies were performed at least three times: at diagnosis, after a patient had been on UDCA for at least 1 year (mean 3.4 years), and after a patient had been on methotrexate for at least 6 months (mean 2.2 years). A fourth liver biopsy was performed in 51 patients after they had been on methotrexate for at least another year (mean 3.5 years)., Results: From the time that methotrexate was begun until the final visit, there were significant decreases in the mean levels of alkaline phosphatase, 323 to 151, ALT, 73 to 39, fibrosis, 2.5 to 2.0, and inflammation scores, 2.0 to 1.0, (p < 0.0001 for all). Based on pre-specified definitions, 73 patients (80%) responded to methotrexate while 18 (20%) did not., Conclusions: In 91 PBC patients who responded incompletely to UDCA, colchicine and methotrexate significantly improved liver enzyme tests and liver histology.

Background: Most patients with autoimmune hepatitis (AIH) require long-term immunosuppressive therapy (IS). While it is well established that solid organ transplant recipients have a high risk of developing non-melanoma skin cancer (NMSC) as a result of immunosuppression, little is known about the risk of NMSC associated with IS in patients with AIH., Objectives: The aim of this study is to determine the incidence and risk factors for NMSC in patients on IS for AIH., Methods: We reviewed the medical records of all patients with AIH seen at a tertiary care medical center between 1998 and 2008. We compared the incidence of NMSC to an age- and sex-matched control population and analyzed risk factors for NMSC., Results: A total of forty-five patients with AIH were identified. Twenty NMSC lesions were found in eight patients. Compared to the age and sex-matched general population, the risk of SCC and BCC were increased as quantified by elevated standardized incidence ratios (28.5 and 5.0, respectively). Patients who developed NMSC were on average 24 years older (78.4 vs. 54.2 years old, p < 0.0001) and had AIH diagnosed at a more advanced age (66.0 vs. 45.4 years old, p = 0.0003)., Conclusion: The risk of NMSC is significantly increased in patients with AIH on immunosuppression. Independent risk factors include current age and age at diagnosis of AIH.

Background and Aim: Although cholesterol levels are elevated in patients with primary biliary cirrhosis (PBC), most PBC patients are not at increased risk of dying from atherosclerotic heart disease. There is, however, a subgroup, approximately 10%, who have additional disorders of lipid metabolism. They might benefit from a cholesterol-lowering agent. However, there is concern about using statins in patients with pre-existing liver disease. We therefore reviewed our experience with statins in a large cohort of PBC patients who were seen at Tufts Medical Center during the past decade., Methods: From January 1, 1996, until June 30, 2006, 603 patients with PBC were seen by one of us (M.M.K.). Fifty-eight were on statins and five were on ezetimibe. The mean duration of usage was 41 months (range 3-125 months). Alanine aminotransferase (ALT) levels were measured at 3-month intervals., Results: Statins were well tolerated. No patient complained of muscle pain or weakness. There was no increase in ALT levels. ALT levels were slightly elevated at the time that statins were begun (41.7 +/- 25.1 U/l), and were normal at the last time these patients were seen (39.0 +/- 21.0 U/l) (P

Modafinil may be a potentially effective treatment for primary biliary cirrhosis (PBC)-related fatigue. About 42 patients were given a 3-day trial of 100-200 mg modafinil. Response was defined as increased energy, decreased somnolence and sleep requirements, and improved daily function. Patients with positive responses were continued indefinitely on the medication. During the initial trial period, 31 (73%) patients had complete response and continued to take the medication. Eleven (26%) had no response. In long-term follow-up (average 17.7 months), 25 (81%) patients continued to take 100-200 mg modafinil daily. Some required an increased dosage and some took the medication as needed. Four (12%) patients stopped the medication because of side-effects or reduced efficacy; one patient (3%) stopped due to medication cost and one (3%) due to resolution of fatigue. Side-effects included insomnia, nausea, nervousness, and headaches. Modafinil appears to be a safe, effective treatment for PBC-related fatigue.

Unlabelled: Primary biliary cirrhosis (PBC) is generally a slowly progressive disease that may lead to cirrhosis and liver failure. However, patients with PBC often suffer from a variety of symptoms long before the development of cirrhosis that include issues of daily living that have an impact on their work environment and their individual quality of life. We therefore examined multiple parameters by taking advantage of the database of our cohort of 1032 patients with PBC and 1041 matched controls. The data were obtained from patients from 23 tertiary referral centers throughout the United States and from rigorously matched controls by age, sex, ethnicity, and random-digit dialing. The data showed that patients with PBC were more likely than controls to have significant articular symptoms, a reduced ability to perform household chores, and the need for help with routine activities. Patients with PBC rated their overall activity similar or superior to that of controls; however, more of them reported limitations in their ability to carry out activities at work or at home and difficulties in everyday activities. PBC cases also more frequently reported limitations in participating in certain sports or exercises and pursuing various hobbies; however, they did not report significant limitations in social activities. In a multivariable analysis, household income, a diagnosis of systemic lupus erythematosus, limitations in work activities, a reduction in work secondary to disability, and church attendance were independently increased in PBC cases with respect to controls., Conclusion: Our data indicate that the quality of life of patients with PBC in the United States is generally well preserved. Nevertheless, patients with PBC suffer significantly more than controls from a variety of symptoms that are beyond the immediate impact of liver failure and affect their lifestyle, personal relationships, and work activities.

Primary biliary cirrhosis (PBC) is an autoimmune disease of unknown etiology, often associated with other autoimmune conditions. Controlled studies have so far provided conflicting data on risk factors and comorbidity rates in PBC. We enrolled patients with PBC (n = 1032) from 23 tertiary referral centers for liver diseases in the United States and random-digit-dialed controls (n = 1041) matched for sex, age, race, and geographical location. Patients and controls were administered a modified version of the US National Health and Nutrition Examination Study (NHANES III) questionnaire by trained personnel to evaluate associations between PBC and social, demographic, personal and family medical histories, lifestyle, and reproductive factors and the rates of comorbidity in affected individuals. Data indicate that having a first-degree relative with PBC (adjusted odds ratio [AOR] 10.736; 95% confidence interval 4.227-27.268), history of urinary tract infections (AOR 1.511, 95% CI 1.192-1.915), past smoking (AOR 1.569, 95% CI 1.292-1.905), or use of hormone replacement therapies (AOR 1.548, 95% CI 1.273-1.882) were significantly associated with increased risk of PBC. The frequent use of nail polish slightly increased the risk of having PBC. Other autoimmune diseases were found in 32% of cases and 13% of controls (P<0.0001). In conclusion, environmental factors, possibly including infectious agents through urinary tract infections or chemicals contained in cigarette smoke, may induce PBC in genetically susceptible individuals. Exogenous estrogens may also contribute to explain the female predominance of the disease.

The prognosis and natural history of primary biliary cirrhosis (PBC) have improved significantly during the last few decades. Patients are diagnosed at earlier stages, are more likely to be asymptomatic at diagnosis, and are more likely to receive medical treatment. The survival of asymptomatic patients is longer than the median survival of symptomatic patients. The natural history of PBC has been assessed in the presence of effective therapy, ursodeoxycholic acid (UDCA). Evidence suggests that UDCA delays histological progression in PBC and decreases the risk of development of esophageal varices. Survival of UDCA-treated patients is better than that of untreated patients and also is better than that predicted by the Mayo model. For patients in early stages of PBC, UDCA treatment may normalize survival. However, patients with stage III and IV PBC do not respond as well to UDCA. Therefore, there is a continued need for additional treatment in patients with advanced disease.

Background and Aims: Sera from patients with primary biliary cirrhosis (PBC) are characterized by the presence of antimitochondrial antibodies and elevated levels of immunoglobulin (Ig) M. We hypothesized that the increase in serum IgM is the result of chronic B-cell activation induced via the Toll-like receptor (TLR) signaling pathway., Methods: We analyzed peripheral blood mononuclear cells (PBMCs) from patients with PBC and controls following incubation with CpG, a natural ligand for TLR9, and determined the basal and stimulated levels of intracellular IgM, the density of TLR9, and the contribution of specific B-cell subpopulations., Results: Our data demonstrate uniquely that in vitro incubation of PBMCs from PBC with CpG-B, but not CpG-A, led to a markedly high frequency of intracellular IgM-positive B cells, associated with high levels of synthesized IgM and identified to be a function of CD27(+) memory B cells. This memory B-cell subset also expressed higher densities of TLR9 as compared with naive B cells. These results were not due to increased proliferation, as defined by 5-carboxyfluoresein diacetate succinimidyl ester labeling, or an increase in the life span of B cells, as defined by Bcl-2 expression., Conclusions: These findings for the first time identify a major role for innate immune mechanisms in the induction and persistence of abnormal humoral immune responses in PBC.

Primary biliary cirrhosis frequently progresses despite treatment with ursodeoxycholic acid (UDCA), the only approved therapy. Previous studies suggested that colchicine and methotrexate may improve biochemical tests of liver function, symptoms, and liver histology. The aim of the present study was to determine if the addition of colchicine or methotrexate to UDCA would improve survival free of liver transplantation. Eighty-five patients with histologically confirmed primary biliary cirrhosis whose serum alkaline phosphatase levels were at least twice the normal level and who were not yet candidates for liver transplantation were randomly assigned to receive colchicine or methotrexate in a double-blind study. UDCA was administered to all patients after 2 years. The primary end point was survival free of liver transplantation. Patients were followed up for a total of up to 10 years or until treatment failure. Data were analyzed on an intention-to-treat basis. Transplant-free survival was similar in both groups: 0.57 for colchicine plus UDCA and 0.44 for methotrexate plus UDCA, results that are similar to those predicted by the Mayo prognostic model. Significant improvement in liver biochemical tests and liver histology was observed in a subset of patients in both treatment groups who remained in the study for all 10 years. In conclusion, neither colchcine plus UDCA nor methotrexate plus UDCA improved survival beyond that predicted by the Mayo prognostic model. However, clinical, histologic, and biochemical improvement observed among those who remained in the study for 10 years suggests a possible benefit of these drugs in a subset of patients.

The shortage of donor organs highlights the need to better identify patients most likely to benefit from hepatic transplantation. Reduced aerobic capacity (decreased peak oxygen consumption [VO(2)] during symptom-limited cardiopulmonary exercise testing) is frequently present in cirrhosis. Peak VO(2) during cardiopulmonary exercise testing may predict short-term outcome after hepatic transplantation. Symptom-limited testing was performed on a cycle ergometer (continuous ramp protocol) and VO(2) determined using a metabolic cart. One hundred fifty-six patients were tested; 59 subsequently underwent hepatic transplantation. Results showed that survivors and nonsurvivors were similar in age, duration of liver disease, Child-Pugh score, MELD score, resting cardiovascular function, pulmonary function, and gas exchange. The 6 (10.2%) patients dying within 100 days of transplantation were more likely to have reduced aerobic capacity (peak VO(2) <60% predicted and VO(2) at anaerobic threshold [VO(2)-AT] <50% predicted peak VO(2)) compared to survivors (4/6 vs. 7/53, P <.01). Using a multiple logistic regression model controlling for duration and severity of liver disease and time to transplantation, reduced aerobic capacity was independently associated with 100-day mortality. In conclusion, reduced aerobic capacity during cardiopulmonary exercise testing is associated with decreased short-term survival after hepatic transplantation. Further study is needed to determine if cardiopulmonary exercise testing can be used to improve allocation of donor organs. To ensure optimum allocation of donor organs, it is important to identify patients most likely to benefit from transplantation. Investigators have identified a number of preoperative, intraoperative, and postoperative factors that predict increased risk for postoperative mortality. Unfortunately, predictive accuracy has not been high, and the timing of factor identification does not optimize organ utilization. Identification of predictors of survival at the time of listing for transplantation might lead to better resource allocation.

There is no effective medical treatment for primary sclerosing cholangitis (PSC), a chronic cholestatic liver disease that usually progresses to cirrhosis and liver failure. The aim of this study was to determine the safety and efficacy of etanercept, an inhibitor of tumor necrosis factor, in the treatment of PSC. Ten patients with clinically active PSC were studied. All had elevated serum alkaline phosphatase levels, cholangiograms that were diagnostic of PSC, and liver histology consistent with PSC. Five patients had elevated serum bilirubin levels, five had pruritus, eight had failed to respond to ursodiol and/or methotrexate, and six had rapidly recurring dominant bile duct strictures. Patients were to receive etanercept, 25 mg subcutaneously twice weekly, for 6 months if there were no side effects and for 1 year if there was evidence of efficacy after 6 months. Biochemical tests of liver function did not improve in any patient. Mean serum bilirubin levels increased significantly, from 2.0 to 3.6 mg/dl (P = 0.026). Two of the five patients with pruritus had resolution of pruritus during treatment with etanercept, recurrence when etanercept was stopped, and resolution when it was restarted, although there was little change in liver enzymes or bilirubin levels. There was no decrease in the rate of stricture formation and there were no side effects. Etanercept, at the dosage used, was well tolerated but not effective in the treatment of PSC. It may be helpful in treating pruritus due to cholestasis.

There is a considerable database on the effector mechanisms for CD8 recognition of PDC-E2 in primary biliary cirrhosis (PBC). In particular, the specific roles of MHC class I, the mitochondrial autoepitope, and the liver-specific T cell precursor frequency, are defined for HLA-A2.1 patients. There is evidence for a role of MHC class I-mediated presentation of exogenous antigens, or cross-presentation, in the development of the antimitochondrial response and a contributory role of Fcgamma receptor-mediated uptake of autoantigen-autoantibody complexes for the induction of a PDC-E2 specific autoreactive CTL response. Based on this background, we examined potential intracellular pathways for processing the immunodominant mitochondrial autoantigen, PDC-E2, by dendritic cells (DC). In particular, we studied the effects of the proteasome inhibitor lactacystin and the endosomal acidification inhibitor bafilomycin on the induction of PDC-E2-specific CTL response in PBC. Importantly, our data indicate that pre-treatment with either lactacystin or bafilomycin inhibits the PDC-E2 immune complex-induced CTL response. The processing and presentation of PDC-E2 by CD8(+)T cells is mediated by proteasomes and facilitated by Fcgamma receptor-mediated endocytosis. This data reflects another layer of interaction between components of the immune system in the development of autoimmunity. Further characterization of autoantigen uptake and processing may lead to potential therapeutic intervention.

Objective: Approximately 20-30% of patients with primary biliary cirrhosis (PBC) respond fully to treatment with ursodeoxycholic acid (UDCA). The rest have progressive disease and eventually develop cirrhosis and liver failure. More effective treatment is needed. Methotrexate improved biochemical tests of liver function and liver histology in patients with PBC who had failed to respond to UDCA in one report and induced sustained biochemical and histological remission in another. The role of colchicine in PBC is unclear. We describe three patients with symptomatic PBC who responded very well to the addition of colchicine after they had failed to respond to UDCA alone and in combination with methotrexate. We suggest that colchicine should be tried in PBC patients who clearly fail to respond to UDCA., Methods: Three patients with symptomatic biopsy-proven, antimitochondrial antibody-positive PBC failed to respond to UDCA and then to the addition of methotrexate. Colchicine was eventually added to the regimen. Symptoms, biochemical tests of liver function, and percutaneous liver biopsies were done at baseline, after treatment with UDCA, UDCA plus methotrexate, and UDCA plus methotrexate plus colchicine., Results: All three patients responded after colchicine was added to UDCA and methotrexate. Symptoms, biochemical tests of liver function, and liver histology improved in all, and blood tests normalized in two., Conclusions: Colchicine may be effective treatment in some symptomatic patients with PBC who respond incompletely to UDCA alone or in combination with methotrexate. Colchicine may be tried in such patients.

Growing evidence has implicated the involvement of autoreactive T lymphocytes in the pathogenesis of primary biliary cirrhosis (PBC). We have recently taken advantage of motif prediction analysis of HLA-A*0201 and identified the first major histocompatibility complex (MHC) class I restricted epitope, amino acids 159 to 167 on E2 components of pyruvate dehydrogenase complexes (PDC-E2), the major mitochondrial antigens in PBC. The mechanisms involved in the selection of epitope peptide(s) that comprise the PDC-E2-specific autoreactive cytotoxic T lymphocytes (CTLs) are unknown and likely involve other epitopes on PDC-E2 restricted by MHC class I molecules. To address this issue, a comprehensive mapping of the CTL epitope repertoire on the PDC-E2 molecule that binds HLA-A*0201 was performed to provide further clues regarding the role of CTLs. We used the T2 cell line to screen 79 overlapping 15mer peptides, spanning the entire PDC-E2 molecule. Six of the 79 peptides exhibited significantly higher binding activity to HLA-A*0201 than the other 15mer peptides. Two of these 6 peptides induced CTL lines from patients with PBC. Fine mapping with N-terminus or C-terminus truncated peptides identified 10mer peptide, PDC-E2 amino acids 165 to 174, which is a novel CD8 epitope restricted by HLA-A*0201. In conclusion, using a combination of the 15mer peptide library screening with the T2 binding assay and also the induction of CTL lines with candidate peptides, we have defined a novel HLA-A*0201-restricted epitope PDC-E2 165 to 174 in patients with PBC. These data will become important in the development of altered peptide ligands to modulate disease activity.

Although the etiology and mechanism of primary biliary cirrhosis (PBC) is unknown, growing evidence suggests a major role for T cells. We have recently identified the first CD8 T-cell epitope, amino acid 159-167 of the E2 component of pyruvate dehydrogenase complexes (PDC-E2). To seek for analogue peptide-antagonizing effector function of CTLs specific for this autoantigen, we examined the effector functions of the PDC-E2-specific CTLs against alanine substituted peptides. Furthermore, because molecular mimicry has been postulated as a possible cause of initiating PBC, we carried out studies aimed at identifying naturally occurring peptides for the 159-167 peptide of PDC-E2 that may serve as agonists. An alanine substitution at position 5 of this epitope significantly reduced peptide-specific effector functions of CTLs. Moreover, this analogue peptide inhibited effector functions of the CTLs to the prototype peptide, including cytotoxicity and IFN-gamma production. We also identified a peptide derived from Pseudomonas aeruginosa, which showed a higher binding affinity to the HLA-A*0201 than the prototype peptide. This homologous peptide was recognized by CTLs specific for the prototype epitope on PDC-E2. In conclusion, a modification of the immunodominant autoepitope can be utilized to manipulate the CD8 T-cell responses against the autoantigen PDC-E2. Our finding also supports the thesis that molecular mimicry may be implicated in the initiation of the autoreactive CD8 T-cell responses and has implications for the use of such peptides for immunotherapy.

Background & Aims: Natural killer T (NKT) cells are a subset of lymphocytes incriminated in playing an important role in the modulation of the innate immune response and the development of autoimmunity. However, there have been only limited studies attempting to quantitate the number of NKT cells in autoimmune disease, particularly because of difficulties associated with definition of this subpopulation., Methods: We used a human CD1d (hCD1d) tetramer produced by a baculovirus expressing recombinant CD1d protein complexed with alpha-galactosylceramide (alpha-GalCer) and quantitated hCD1d tetramer reactive cells in blood and liver from controls and patients with primary biliary cirrhosis (PBC)., Results: The majority of CD1d-alphaGalCer-restricted NKT cells were positive for TCR Valpha24 and Vbeta11. There was a distinct CD4- CD8+ population within the CD1d-alphaGalCer-restricted NKT cells in addition to the CD4- CD8- and CD4+ CD8- population. The frequency of CD1d-alphaGalCer-restricted NKT cells was similar between blood and liver in healthy individuals. In contrast, the frequency of CD1d-alphaGalCer-restricted NKT cells in the liver was significantly higher than in the blood of PBC patients. The frequency of CD1d-alpha-GalCer-restricted NKT cells in the liver was also significantly higher in PBC patients than in healthy individuals., Conclusions: The frequency and function of such cells should be studied not only in blood but also in the target organ of the autoimmune disease. Selective enrichment of CD1d-alphaGalCer-restricted NKT cells at the site of inflammation is observed in PBC, suggesting a role of these cells in the development of PBC.

Anti-mitochondrial antibodies (AMA) are present in sera of approximately 90-95% of patients with primary biliary cirrhosis (PBC) and, thus, constitute one of the most important diagnostic criteria for this disease. The major mitochondrial autoantigens have been identified, cloned, and sequenced and the immunological features of AMA, including their antigen specificities and epitopes, have been well characterized. In clinical laboratories, indirect immunofluorescence (IIF) microscopy is routinely employed for the detection of AMA mainly because of technical simplicity and cost effectiveness. However, IIF lacks both specificity and sensitivity, and in up to 10% of patients diagnosed with PBC based on standard diagnostic criteria, AMA cannot be detected by IIF. In some of these patients, AMA aredetectable by more sensitive techniques, such as enzyme-linked immunosorbent assays (ELISAs) or SDS-PAGE followed by immunoblotting. Nonetheless, there are patients whose sea are negative for AMA by any of these methods despite clinical, biochemical, and histological findings that are diagnostic for PBC. Some have argued that AMA-positive and AMA-negative PBC represent two distinct entities, but recent evidence supports the view that they are clinically and biochemically quite similar. The situation is further complicated by the fact that AMA, even those recognizing the major PBC autoantigens, are also present in a variety of other liver diseases. In addition, patients exhibiting the clinical, histological, and biochemical features of both PBC and autoimmune hepatitis, the so-called 'overlap syndrome,' are not uncommon. In conclusion, AMA status, though invaluable in establishing and confirming the diagnosis of PBC in > or =90% of PBC patients, is not sufficient by itself to allow the differential diagnosis of liver diseases. The choice of therapeutic regimen should, therefore, be based on a combination of serological, biochemical and histological findings, rather than AMA status alone.

While the pathologic mechanisms responsible for organ-specific tissue damage in primary biliary cirrhosis (PBC) remain an enigma, it has been suggested that the pathology is mediated by autoreactive T cells infiltrating the intrahepatic bile ducts. Previously, we have documented that there is 100-fold enrichment in the frequency of CD4(+) autoreactive T cells in the liver that are specific for peptides encoded by the E2 components of the pyruvate dehydrogenase complexes (PDC-E2). We have also recently characterized the first MHC class I-restricted epitope for PDC-E2, namely amino acid 159-167, a region very similar to the epitope recognized by MHC class II-restricted CD4(+) cells and by autoantibodies. The effector functions of these PDC-E2(159-167)-specific CD8(+) cytotoxic T lymphocytes (CTLs) are not well understood. We have taken advantage of tetramer technology and report herein that there is tenfold increase in the frequency of PDC-E2(159-167)-specific CTLs in the liver as compared with the blood in PBC. In addition, the precursor frequency of the CTLs in blood was significantly higher in early-stage PBC. Of interest was the fact that, upon stimulation with the peptide, the response of PDC-E2(159-167) tetramer-positive cells is heterogeneous with respect to IFN-gamma synthesis. These data, we believe for the first time, document the enrichment of autoantigen-specific CD8(+) T cells in the PBC liver, suggesting that CD8(+) T cells play a significant role in the immunopathogenesis of PBC.

Guidelines for clinical practice are intended to indicate preferred approaches to medical problems as established by scientifically valid research. Double blind, placebo-controlled studies are preferable, but reports and expert review articles are also utilized in a thorough review of the literature conducted through the National Library of Medicine's MEDLINE. When only data that will not withstand objective scrutiny are available, a recommendation is identified as a consensus of experts. Guidelines are applicable to all physicians who address the subject, without regard to specialty training or interests, and are intended to indicate the preferable but not necessarily the only acceptable approach to a specific problem. Guidelines are intended to be flexible and must be distinguished from standards of care that are inflexible and rarely violated. Given the wide range of specifics in any health care problem, the physician must always choose the course best suited to the individual patient and the variables in existence at the moment of decision. Guidelines are developed under the auspices of the American College of Gastroenterology and its Practice Parameters Committee and approved by the Board of Trustees. Each has been intensely reviewed and revised by the Committee, other experts in the field, physicians who will use them, and specialists in the science of decision of analysis. The recommendations of each guideline are therefore considered valid at the time of their production based on the data available. New developments in medical research and practice pertinent to each guideline will be reviewed at an established time and indicated at publication to assure continued validity.

Primary biliary cirrhosis (PBC) is characterized by an intense biliary inflammatory CD4(+) and CD8(+) T cell response. Very limited information on autoantigen-specific cytotoxic T lymphocyte (CTL) responses is available compared with autoreactive CD4(+) T cell responses. Using peripheral blood mononuclear cells (PBMCs) from PBC, we identified an HLA-A2-restricted CTL epitope of the E2 component of pyruvate dehydrogenase (PDC-E2), the immunodominant mitochondrial autoantigen. This peptide, amino acids 159-167 of PDC-E2, induces specific MHC class I-restricted CD8(+) CTL lines from 10/12 HLA-A2(+) PBC patients, but not controls, after in vitro stimulation with antigen-pulsed dendritic cells (DCs). PDC-E2-specific CTLs could also be generated by pulsing DCs with full-length recombinant PDC-E2 protein. Furthermore, using soluble PDC-E2 complexed with either PDC-E2-specific human monoclonal antibody or affinity-purified autoantibodies against PDC-E2, the generation of PDC-E2-specific CTLs, occurred at 100-fold and 10-fold less concentration, respectively, compared with soluble antigen alone. Collectively, these data demonstrate that autoantibody, helper, and CTL epitopes all contain a shared peptide sequence. The finding that autoantigen-immune complexes can not only cross-present but also that presentation of the autoantigen is of a higher relative efficiency, for the first time defines a unique role for autoantibodies in the pathogenesis of an autoimmune disease.