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Epithelial cell specificity and apotope recognition by serum autoantibodies in primary biliary cirrhosis.

ABSTRACT: A major enigma of primary biliary cirrhosis (PBC) is the selective targeting of biliary cells. Our laboratory has reported that after apoptosis, human intrahepatic biliary epithelial cells (HiBECs) translocate the E2 subunit of the pyruvate dehydrogenase complex immunologically intact into apoptotic bodies, forming an apotope. However, the cell type and specificity of this reaction has not been fully defined. To address this issue, we investigated whether the E2 subunit of the pyruvate dehydrogenase complex, the E2 subunit of the branched chain 2-oxo acid dehydrogenase complex, the E2 subunit of the oxo-glutarate dehydrogenase complex, four additional inner mitochondrial enzymes, and four nuclear antigens remain immunologically intact with respect to postapoptotic translocation in HiBECs and three additional control epithelial cells. We report that all three 2-oxo acid dehydrogenase enzymes share the ability to remain intact within the apotope of HiBECs. Interestingly, the E2 subunit of the branched chain 2-oxo acid dehydrogenase complex also remained intact in the other cell types tested. We extended the data, using sera from 95 AMA-positive and 19 AMA-negative patients with PBC and 76 controls, by testing for reactivity against the seven mitochondrial proteins studied herein and also the ability of AMA-negative sera to react with HiBEC apotopes. Sera from 3 of 95 AMA-positive sera, but none of the controls, reacted with 2,4-dienoyl coenzyme A reductase 1, an enzyme also present intact only in the HiBEC apotope, but which has not been previously associated with any autoimmune disease. Finally, the specificity of HiBEC apotope reactivity was confined to AMA-positive sera.We submit that the biliary specificity of PBC is secondary to the unique processes of biliary apoptosis.

SUBMITTER: Rong G

PROVIDER: S-EPMC3125447 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Epithelial cell specificity and apotope recognition by serum autoantibodies in primary biliary cirrhosis.

Rong Guanghua G Zhong Renqian R Lleo Ana A Leung Patrick S C PS Bowlus Christopher L CL Yang Guo-Xiang GX Yang Chen-Yen CY Coppel Ross L RL Ansari Aftab A AA Cuebas Dean A DA Worman Howard J HJ Invernizzi Pietro P Gores Gregory J GJ Norman Gary G He Xiao-Song XS Gershwin M Eric ME

Hepatology (Baltimore, Md.) 20110701 1

<h4>Unlabelled</h4>A major enigma of primary biliary cirrhosis (PBC) is the selective targeting of biliary cells. Our laboratory has reported that after apoptosis, human intrahepatic biliary epithelial cells (HiBECs) translocate the E2 subunit of the pyruvate dehydrogenase complex immunologically intact into apoptotic bodies, forming an apotope. However, the cell type and specificity of this reaction has not been fully defined. To address this issue, we investigated whether the E2 subunit of the ...[more]

PMID: 21488079

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Project description:Primary biliary cirrhosis (PBC) is an immune-mediated chronic cholestatic liver disease with a slowly progressive course. Without treatment, most patients eventually develop fibrosis and cirrhosis of the liver and may need liver transplantation in the late stage of disease. PBC primarily affects women (female preponderance 9-10:1) with a prevalence of up to 1 in 1,000 women over 40 years of age. Common symptoms of the disease are fatigue and pruritus, but most patients are asymptomatic at first presentation. The diagnosis is based on sustained elevation of serum markers of cholestasis, i.e., alkaline phosphatase and gamma-glutamyl transferase, and the presence of serum antimitochondrial antibodies directed against the E2 subunit of the pyruvate dehydrogenase complex. Histologically, PBC is characterized by florid bile duct lesions with damage to biliary epithelial cells, an often dense portal inflammatory infiltrate and progressive loss of small intrahepatic bile ducts. Although the insight into pathogenetic aspects of PBC has grown enormously during the recent decade and numerous genetic, environmental, and infectious factors have been disclosed which may contribute to the development of PBC, the precise pathogenesis remains enigmatic. Ursodeoxycholic acid (UDCA) is currently the only FDA-approved medical treatment for PBC. When administered at adequate doses of 13-15 mg/kg/day, up to two out of three patients with PBC may have a normal life expectancy without additional therapeutic measures. The mode of action of UDCA is still under discussion, but stimulation of impaired hepatocellular and cholangiocellular secretion, detoxification of bile, and antiapoptotic effects may represent key mechanisms. One out of three patients does not adequately respond to UDCA therapy and may need additional medical therapy and/or liver transplantation. This review summarizes current knowledge on the clinical, diagnostic, pathogenetic, and therapeutic aspects of PBC.

Dataset Information

Epithelial cell specificity and apotope recognition by serum autoantibodies in primary biliary cirrhosis.

Publications

Epithelial cell specificity and apotope recognition by serum autoantibodies in primary biliary cirrhosis.

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