原发性胆汁性肝硬化抗线粒体抗体M_2亚型检测方法和临床评估

目的 研究抗线粒体抗体 (AMA)M2 亚型检测对原发性胆汁性肝硬化 (PBC)的诊断价值。方法 应用酶联免疫吸附试验 (ELISA) ,检测人血清中M2 抗体含量。共检测正常人 2 0名 ,PBC患者 3 7例 ,其他肝病患者 5 0例。结果 ELISA法检测M2 抗体重复性好 ,灵敏度高 ,特异性强。 3 7例PBC患者中有 3 6例阳性 (>5U/ml) ,只有 1例阴性。而其它肝胆系患者 5 0例 ,3例为假阳性。灵敏度为 97.3 % ,特异性为 94.0 %。正常人均为阴性。PBC患者M2 抗体滴度为 (73 .66± 5 5 .93 )U/ml,较正常人 (1.60± 1.13 )U /ml显著升高 (P <0 .0 1) ,其他肝胆系患者M2 抗体滴度 (2 .90±3 .16)U/ml与正常人相比无显著差别 (P >0 .0 5 )。结论 M2

New insights into the pathogenesis of primary biliary cholangitis asymptomatic stage

Primary biliary cholangitis(PBC)is a chronic cholestatic progressive liver disease and one of the most important progressive cholangiopathies in adults.Damage to cholangiocytes triggers the development of intrahepatic cholestasis,which progresses to cirrhosis in the terminal stage of the disease.Accumulating data indicate that damage to biliary epithelial cells[(BECs),cholangiocytes]is most likely associated with the intracellular accumulation of bile acids,which have potent detergent properties and damaging effects on cell membranes.The mechanisms underlying uncontrolled bile acid intake into BECs in PBC are associated with pH change in the bile duct lumen,which is controlled by the bicarbonate(HCO3-)buffer system“biliary HCO3-umbrella”.The impaired production and entry of HCO3-from BECs into the bile duct lumen is due to epigenetic changes in expression of the X-linked microRNA 506.Based on the growing body of knowledge on the molecular mechanisms of cholangiocyte damage in patients with PBC,we propose a hypothesis explaining the pathogenesis of the first morphologic(ductulopenia),immunologic(antimitochondrial autoantibodies)and clinical(weakness,malaise,rapid fatigue)signs of the disease in the asymptomatic stage.This review focuses on the consideration of these mechanisms.

Transient positive antimitochondrial M2 in sera of patients with connective tissue diseases after intravenous immunoglobulin infusions

Background:Although antinuclear antibodies(ANAs),anti‐SSA and anti‐Ro52,are present in immunoglobulin preparations,it is unknown whether intravenous immunoglobulin(IVIG)therapy influences the testing of serum autoantibodies in patients with connective tissue diseases(CTDs).The present study aimed to investigate the dynamic change over time of serum ANA‐related autoantibodies in patients with CTDs receiving IVIG therapy.Methods:Serum ANA‐related autoantibodies were monitored in two patients with CTD before IVIG therapy and at different times after therapy.These autoantibodies were tested in different batches of immunoglobulin preparations from seven pharmaceutical companies.Results:One patient developed a new ANA pattern(cytoplasmic dense fine speckled pattern,AC‐19)just after IVIG therapy.Both patients developed de novo positivity for AMA‐M2 and anti‐SSA,but returned negative 1 month after IVIG therapy.The residual liquid in patients'immunoglobulin preparations showed positive ANAs with a high titer of AC‐19(1:640),a low titer of the nuclear fine speckled pattern(AC‐4,1:80),positive AMA‐M2,and positive anti‐SSA.ANA‐related autoantibodies were tested in 16 batches of immunoglobulin preparations and all had positive ANAs with two patterns:AC‐19(1:640 or 1:320)and AC‐4(1:80).AMA‐M2 and anti‐SSA were positive in 100%of the batches.Conclusion:Our study highlights high‐titer AMA‐M2 autoantibodies in immunoglobulin preparations and suggests their transient transfer into a patient's circulation via IVIG therapy.To avoid incorrect clinical decisions based on postinfusion antibody titers,our data recommend retesting 1–2 months after high‐dose IVIG immunomodulatory treatment.

Xenobiotics and loss of tolerance in primary biliary cholangitis

Data from genome wide association studies and geoepidemiological studies established that a com-bination of genetic predisposition and environmental stimulation is required for the loss of tolerance in primary biliary cholangitis(PBC).The serologic hallmark of PBC are the presence of high titer anti-mitochondrial autoantibodies(AMA)that recognize the lipoyl domain of the mitochondrial pyruvate dehydrogenase E2(PDC--E2)subunit.Extensive efforts have been directed to investigate the molecular basis of AMA.Recently,experimental data has pointed to the thesis that the breaking of tolerance to PDC--E2 is a pivotal event in the initial etiology of PBC,including environmental xenobiotics including those commonly found in cos-metics and food additives,suggesting that chemical modification of the PDC--E2 epitope may render its vulnerable to become a neo-antigen and trigger an immune response in genetically susceptible hosts.Here,we will discuss the natural history,genetics and immunobiology of PBC and structural constraints of PDC--E2 in AMA recognition which makes it vulnerable to chemical modification.

Enzyme inhibition assay for pyruvate dehydrogenase complex: Clinical utility for the diagnosis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is usually diagnosed by the presence of characteristic histopathological features of the liver and/or antimitochondrial antibodies (AMA) in the serum traditionally detected by immunofluorescence. Recently, new and more accurate serological assays for the detection of AMA, such as enzyme-linked immunosorbent assay (ELISA), immunoblotting, and enzyme inhibition assay, have been developed. Of these, the enzyme inhibition assay for the detection of anti-pyruvate dehydrogenase complex (PDC) antibodies offers certain advantages such as objectivity, rapidity, simplicity, and low cost. Since this assay has almost 100% specificity, it may have particular applicability in screening the at-risk segment of the population in developing countries. Moreover, this assay could be also used for monitoring the disease course in PBC. Almost all sera of PBC-suspected patients can be confirmed for PBC or non-PBC by the combination results of immunoblotting and enzyme inhibition assay without histopathological examination. For the development of a "complete" or "gold standard" diagnostic assay for PBC, similar assays of the enzyme inhibition for anti-2-oxoglutarate dehydrogenase complex (OGDC) and anti-branched chain oxo-acid dehydrogenase complex (BCOADC) antibodies will be needed in future.