Clinical evaluation of serum antimitochondrial antibody-negative primary biliary cirrhosis

BACKGROUND: Primary biliary cirrhosis (PBC) is cha- racterized by frequent presence of antimitochondrial anti- bodies (AMAs). The sensitivity and specificity of AMA for PBC are both greater than 90%-95%, so the presence of AMA in serum is the major hallmark in PBC. However, it has long been recognized that in 5%-10% of patients the clinical, biochemical and histological features are diagnos- tic for PBC, but their sera are consistently tested negative for AMA/AMA-M2. This study aimed to evaluate whether the presence of AMA alters the clinical, serological and his- tological features of the disease. METHODS: Clinical data of 70 patients clinically and/or histologically diagnosed with PBC were reviewed. AMA- negative and AMA-positive patients were compared in terms of clinical, biochemical, immunological and histo- logical features. RESULTS: At presentation, 11 patients were serum AMA/ AMA-M2 negative. At the initial visit, AMA-negative and AMA-positive patients were similar in terms of age, sex, clinical manifestations, liver biochemistries and histological findings. The mean level of serum immunoglobulin M (IgM) was significantly lower in AMA-negative PBC pa- tients than in AMA-positive PBC patients (2851±1418 mg/L vs 6361 ±4928 mg/L, P =0.033). Serum antinuclear anti- bodies ( ANA) and/or smooth muscle antibodies ( SMA) were more frequently positive in the AMA-negative PBC patients than in the AMA-positive patients (81.8% vs 40.7%, P =0.031). CONCLUSION: AMA-negative PBC patients are characte- rized by relatively lower levels of serum IgM and a higher prevalence of serum ANA/SMA and are not associated with substantial differences in the clinical, biochemical and histo- logical spectrum of the disease.

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.

Sequence of events leading to primary biliary cholangitis

Primary biliary cholangitis(PBC)is a chronic cholestatic liver disease that is observed more frequently in middle-aged women.This disorder is considered an autoimmune disease,since liver injury is sustained by the presence of selfdirected antimitochondrial antibodies targeting the bile duct cells.The prognosis may vary depending on an early diagnosis and response to therapy.However,nearly a third of patients can progress to liver cirrhosis,thus requiring a liver transplant.Traditional immunosuppressive therapies,commonly employed for other autoimmune diseases,have limited effects on PBC.In fact,dramatic functional changes that occur in the biliary epithelium in the course of inflammation play a major role in perpetuating the injury.In this minireview,after a background on the disease and possible predisposing factors,the sequential cooperation of cellular/molecular events leading to end-stage PBC is discussed in detail.The rise and maintenance of the autoimmune process,as well as the response of the biliary epithelia during inflammatory injury,are key factors in the progression of the disease.The so-called“ductular reaction(DR)”,intended as a reactive expansion of cells with biliary phenotype,is a process frequently observed in PBC and partially understood.However,recent findings suggest a strict relationship between this pathological picture and the progression to liver fibrosis,cell senescence,and loss of biliary ducts.All these issues(onset of chronic inflammation,changes in secretive and proliferative biliary functions,DR,and its relationship with other pathological events)are discussed in this manuscript in an attempt to provide a snapshot,for clinicians and researchers,of the most relevant and sequential contributors to the progression of this human cholestatic disease.We believe that interpreting this disorder as a multistep process may help identify possible therapeutic targets to prevent evolution to severe disease.

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.

Clinicopathological features of 11 cases of chronic hepatitis B infection complicated with primary biliary cholangitis

BACKGROUND Only a few cases of chronic hepatitis B(CHB)with primary biliary cholangitis(PBC)have been reported based on histological evidence from liver biopsies.AIM To observe the clinicopathological features and outcomes of 11 patients with CHB infection complicated by PBC.METHODS Eleven patients with CHB and PBC who underwent liver biopsy at the Zhenjiang Third Hospital,affiliated with Jiangsu University,and Wuxi Fifth People’s Hospital,from January 2005 to September 2020,were selected.All patients initially visited our hospital with CHB and were pathologically diagnosed with CHB and PBC.RESULTS Only five had elevated alkaline phosphatase levels,nine were positive for antimitochondrial antibody(AMA)-M2,and two were negative for AMA-M2.Two had jaundice and pruritus symptoms,10 had mildly abnormal liver function,and one had severely elevated bilirubin and liver enzyme levels.The pathological characteristics of CHB complicated by PBC overlapped with those of PBCautoimmune hepatitis(AIH).When necroinflammation of the portal area is not obvious,the pathological features of PBC are predominant,similar to the features of PBC alone.When the interface is severe,biliangitis will occur,with a large number of ductular reactions in zone 3.Unlike the PBC-AIH overlap pathology,this pathology is characterized by a small amount of plasma cell infiltration.Unlike PBC,lobulitis is often observed.CONCLUSION This is the first large case series to show that the rare pathological features of CHB with PBC are similar to those of PBC-AIH and small duct injury was observed.

Peri-nuclear antibodies correlate with survival in Greek primary biliary cirrhosis patients

AIM:To investigate possible associations of anti-nuclear envelope antibody(ANEA)with disease severity and survival in Greek primary biliary cirrhosis(PBC)patients.METHODS:Serum samples were collected at diagnosis from 147 PBC patients(85%female),who were followed-up for a median 89.5 mo(range 1-240).ANEA were detected with indirect immunofluorescence on 1% formaldehyde fixed Hep2 cells,and anti-gp210 antibodies were detected using an enzyme linked immunosorbent assay.Findings were correlated with clinical data,histology,and survival.RESULTS:ANEA were detected in 69/147(46.9%) patients and 31/147(21%)were also anti-gp210 positive.The ANEA positive patients were at a more advanced histological stage(Ⅰ-Ⅱ/Ⅲ-Ⅳ56.5%/43.5% vs 74.4%/25.6%,P=0.005)compared to the ANEA negative ones.They had a higher antimitochondrial antibodies(AMA)titer(≤1:160/>1:160 50.7%/49.3%vs 71.8%/28.2%,P=0.001)and a lower survival time(91.7 ±50.7 mo vs 101.8±55 mo,P=0.043).Moreover,they had more advanced fibrosis,portal inflammation,interface hepatitis,and proliferation of bile ductules(P =0.008,P=0.008,P=0.019,and P=0.027,respectively).They also died more frequently of hepatic failure and/or hepatocellular carcinoma(P=0.016).ANEA positive,anti-gp210 positive patients had a difference in stage(Ⅰ-Ⅱ/Ⅲ-Ⅳ54.8%/45.2%vs 74.4%/25.6%,P= 0.006),AMA titer(≤1:160/>1:160 51.6%/48.4%vs 71.8%/28.2%,P=0.009),survival(91.1±52.9 mo vs 101.8±55 mo,P=0.009),and Mayo risk score(5.5 ±1.9 vs 5.04±1.3,P=0.04)compared to the ANEA negative patients.ANEA positive,anti-gp210 negative patients had a difference in AMA titer(≤1:160/>1:160 50%/50%vs 71.8%/28.2%,P=0.002),stage(Ⅰ-Ⅱ/Ⅲ -Ⅳ57.9%/42.1%vs 74.4%/25.6%,P=0.033),fibrosis(P=0.009),portal inflammation(P=0.018),interface hepatitis(P=0.032),and proliferation of bile ductules(P=0.031).Anti-gp210 positive patients had a worse Mayo risk score(5.5±1.9 vs 4.9±1.7,P=0.038)than the anti-gp210 negative ones.CONCLUSION:The presence of ANEA and anti-gp210 identifies a subgroup of PBC patients with advanced disease severity and poor prognosis.

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.

Primary biliary cirrhosis-specific autoantibodies in first degree relatives of Greek primary biliary cirrhosis patients

AIM:To determine the prevalence and significance of primary biliary cirrhosis (PBC)-specific autoantibodies in firstdegree relatives (FDRs) of Greek PBC patients. METHODS:The presence of antimitochondrial antibodies (AMA) and PBCspecific antinuclear antibodies (ANA) were determined using indirect immunofluores-cence assays, dot-blot assays, and molecularly based enzyme-linked immunosorbent assays in 101 asymp-tomatic for liver-related symptoms FDRs of 44 PBCpatients. In order to specify our results, the same investigation was performed in 40 healthy controls and in a disease control group consisting of 40 asymptomatic for liver-related symptoms FDRs of patients with other autoimmune liver diseases namely, autoimmune hepati-tis-1 or primary sclerosing cholangitis (AIH-1/PSC). RESULTS: AMA positivity was observed in 19 (only 4 with abnormal liver function tests) FDRs of PBC patients and none of the healthy controls. The preva-lence of AMA was significantly higher in FDRs of PBC patients than in AIH-1/PSC FDRs and healthy controls [18.8%, 95% confidence interval (CI):12%-28.1% vs 2.5%, 95% CI:0.1%-14.7%, P = 0.01; 18.8%, 95% CI:12%-28.1% vs 0%, 95% CI: 0%-10.9%, P = 0.003, respectively]. PBC-specific ANA positivity was observed in only one FDR from a PSC patient. Multivariate analysis showed that having a proband with PBC independently associated with AMA positivity (odds ratio: 11.24, 95% CI:1.27-25.34, P = 0.03) whereas among the investigated comorbidities and risk factors, a positive past history for urinary tract infections (UTI) was also independently associated with AMA detection in FDRs of PBC patients (odds ratio:3.92, 95% CI:1.25-12.35,P = 0.02). CONCLUSION:In FDRs of Greek PBC patients, AMA prevalence is significantly increased and independently associated with past UTI. PBC-specific ANA were not detected in anyone of PBC FDRs.

Role for mycobacterial infection in pathogenesis of primary biliary cirrhosis?

Primary biliary cirrhosis （PBC） is a progressive cho- lestatic liver disease characterized by the immune- mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characterized by circulating antimitochondrial antibodies （AMAs） as well as disease-specific antinuclear antibodies, cholestatic liver function tests, and characteristic histological fea- tures, including granulomas. A variety of organisms are involved in granuloma formation, of which mycobacte- ria are the most commonly associated. This has led to the hypothesis that mnycobacteria may be involved in the pathogenesis of PBC, along with other infectious agents. Additionally, AMAs are found in a subgroup of patients with rnycobacterial infections, such as lep- rosy and pulmonary tuberculosis. Antibodies against species-specific mycobacterial proteins have been re- ported in patients with PBC, but it is not clear whether these antibodies are specific for the disease. In addi- tion, data in support of the involvement of the role of molecular mimicry between rnycobacterial and human mitochondrial antigens as triggers of cross-reactive im- mune responses leading to the loss of immunological tolerance, and the induction of pathological features have been published. Thus, antibodies against myco- bacterial heat shock protein appear to cross-recognize AMA-specific autoantigens, but it is not clear whether these autoantibodies are mycobacterium-species-spe- cific, and whether they are pathogenic or incidental. The view that mycobacteria are infectious triggers of PBC is intriguing, but the data provided so far are not conclusive.