Etiopathogenesis of primary biliary cirrhosis

Causal Association Between Circulating Inflammatory Proteins and Autoimmune Liver Disease: a Bidirectional Two-Sample Mendelian Randomization Study

Introduction

To investigate whether there is a direct causal relationship between circulating inflammatory proteins and autoimmune liver disease (AILD).

Materials and Methods

We collected genetic data for various AILD from the Genome Wide Association Studies (GWAS) dataset. The latest research provides GWAS data for 91 proteins associated with inflammation. Perform bidirectional two sample Mendelian randomization (MR) analysis using inverse variance weighted (IVW) to determine the causal relationship between inflammatory proteins and AILD, and use Mendelian randomization Egger method (MR Egger), weighted median (WM), and weighted mode as supplementary evaluations. In addition, we conducted sensitivity analysis.

Results

Positive MR analysis showed that CDCP1 (OR=1.363, p=0.0465) and IL-18 (OR=1.416, p=0.0477) were associated with higher including autoimmune hepatitis (AIH) risk. Higher CXCL11 (OR=1.574, p=9.23×10-5) were associated with an increased risk of primary biliary cholangitis (PBC). Lower levels of three inflammatory proteins were associated with increased risk of PBC. TNFSF12 (OR=1.827, p=0.0001, p_adj_fdr=0.0063), CD6 isoform (OR=1.126, p=0.0389), CCL20 (OR=1.880, p=0.0395) are associated with increased risk of primary sclerosing cholangitis (PSC). Reverse MR imaging showed that PBC may promote the expression levels of CCL4 (OR=1.023, p=0.0201) and OSM (OR=1.022, p=0.0236). PSC may promote the expression of five inflammatory proteins. Sensitivity analysis further excluded the effects of heterogeneity and horizontal pleiotropy.

Conclusion

This study indicates a potential association between circulating inflammatory proteins and AILD, which may become a new diagnostic indicator or drug target for clinical application in the prevention and treatment of AILD. However, further investigation is needed.

Mechanism of formation and significance of antimitochondrial autoantibodies in the pathogenesis of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic progressive liver disease associated with cholangiopathies. The detection of antimitochondrial autoantibodies (AMAs) plays an important role in the diagnosis of classical PBC. AMAs are formed against the antigenic component associated with the dihydrolipoyl transacetylase of pyruvate dehydrogenase complex (E2 PDC) localized on the inner membrane of mitochondria. The loss of immune tolerance of E2 PDC in PBC is thought to be the cause of the mechanism of AMA formation and immune-mediated destruction of biliary epithelial cells (BECs) of the small- and medium-sized intrahepatic bile ducts. E2 PDC is not only present in BECs, but is also abundant in the mitochondria of all nucleated cells. The question remains as to why E2 PDC of only small BECs is the target of autoimmune attack. There is no evidence that AMAs have a deleterious effect on BECs. New scientific data has emerged that explains the damage to BECs in PBC by the defect of the biliary bicarbonate (HCO3–) “umbrella” that protects BECs from the detergent action of bile acids under physiological conditions. Disruption of HCO3– production by BECs in PBC leads to changes in the pH of hepatic bile, accompanied by accumulation of bile acids in the small BECs. The detergent action of bile acids leads to damage of membrane structures of BECs and their apoptosis, development of ductulopenia, and intrahepatic cholestasis. For the first time, it has been suggested that under the influence of bile acids, the E2 PDC antigen may undergo conformational changes that alter its immunological properties. E2 PDC becomes a neoantigen that is recognized by the normal (“healthy”) immune system as a foreign antigen, leading to the production of AMAs. For the first time, the authors of this review provide an explanation for why only small BECs are damaged in PBC.

High neutrophil-lymphocyte ratio indicates a worse response to ursodeoxycholic acid in primary biliary cholangitis: a retrospective cohort study

BACKGROUND

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease characterized by inflammation of the interlobular bile ducts. Ursodeoxycholic acid (UDCA) is the only FDA approved first-line therapy for PBC, but up to 40% of patients with PBC have an incomplete response to UDCA. Neutrophil-to-lymphocyte (NLR) has been used to predict prognosis in various liver diseases. There is limited evidence on the treatment response to UDCA in PBC patients. Our study aimed to evaluate the relationship between NRL and the response to UDCA treatment in PBC patients.

METHODS

A total of 257 primary biliary cholangitis (PBC) patients treated with UDCA (13-15 mg/kg/d) were enrolled in this retrospective study. The response to treatment was evaluated based on alkaline phosphatase levels ≤1.67 times the upper limit of the normal value after 12 months of UDCA treatment. Multivariable logistic regression analysis was performed to investigate the association between NLR at baseline and the response to 12 months of UDCA treatment after adjusting for important confounding variables. The stability of the results was evaluated by unadjusted and adjusted models.

RESULTS

The results of multiple regression analysis showed that NLR at baseline was positively associated with the nonresponse to UDCA treatment after adjustments for potential confounders (age, sex, BMI, hypertension, arterial plaque, thyroid disease, jaundice, albumin, globulin, total bile acid, ALP, GGT, LDLC, total cholesterol, hemoglobin, and APTT) (OR = 1.370, 95% CI 1.066-1.761). These results reveal that NLR is an independent risk factor for UDCA treatment nonresponse.

CONCLUSIONS

Our results suggest that PBC patients with a high NLR had a worse response to UDCA therapy.

Diagnostic value of anti-mitochondrial antibody in patients with primary biliary cholangitis: A systemic review and meta-analysis

BACKGROUND

Anti-mitochondrial antibodies (AMA) and the M2 subtype are considered serological hallmarks in the diagnosis of primary biliary cholangitis (PBC). However, these autoantibodies may be undetectable in some patients. This meta-analysis aimed to evaluate the diagnostic accuracy of serum AMA and M2 for PBC.

METHODS

We systematically searched PubMed, Embase, Web of Science, and the Cochrane Library for relevant studies. Pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) were calculated using a random-effects model. We also constructed hierarchical summary receiver operating characteristic curves and calculated the area under the curve values.

RESULTS

Our meta-analysis included 28 studies, of which 24 examined the diagnostic accuracy of AMA for PBC. Pooled sensitivity and specificity of AMA were 84% (95% confidence intervals [CI] 77-90%) and 98% (96-99%), respectively. Pooled LR+, LR-, and DOR were 42.2 (22.1-80.5), 0.16 (0.11-0.24), and 262 (114-601), respectively. Sixteen studies explored the diagnostic value of the M2 subtype, demonstrating pooled sensitivity and specificity of 89% (81-94%) and 96% (93-98%), respectively. Pooled LR+, LR-, and DOR were 20.3 (8.0-51.1), 0.12 (0.05-0.26), and 169 (41-706), respectively. The hierarchical summary receiver operating characteristic curves for both of serum AMA and M2 subtype lie closer to the upper left corner of the plot with area under the curve values of 0.98 (95% CI = 0.96-0.99) and 0.98 (95% CI = 0.96-0.99) respectively.

CONCLUSION

This meta-analysis provides evidence affirming the utility of AMA and M2 as sensitive and specific serological hallmarks that can facilitate early screening and diagnosis of PBC.

The role of sialic acid-binding immunoglobulin-like-lectin-1 (siglec-1) in immunology and infectious disease

Siglec-1, also known as Sialoadhesin (Sn) and CD169 is highly conserved among vertebrates and with 17 immunoglobulin-like domains is Siglec-1 the largest member of the Siglec family. Expression of Siglec-1 is found primarily on dendritic cells (DCs), macrophages and interferon induced monocyte. The structure of Siglec-1 is unique among siglecs and its function as a receptor is also different compared to other receptors in this class as it contains the most extracellular domains out of all the siglecs. However, the ability of Siglec-1 to internalize antigens and to pass them on to lymphocytes by allowing dendritic cells and macrophages to act as antigen presenting cells, is the main reason that has granted Siglec-1's key role in multiple human disease states including atherosclerosis, coronary artery disease, autoimmune diseases, cell-cell signaling, immunology, and more importantly bacterial and viral infections. Enveloped viruses for example have been shown to manipulate Siglec-1 to increase their virulence by binding to sialic acids present on the virus glycoproteins allowing them to spread or evade immune response. Siglec-1 mediates dissemination of HIV-1 in activated tissues enhancing viral spread via infection of DC/T-cell synapses. Overall, the ability of Siglec-1 to bind a variety of target cells within the immune system such as erythrocytes, B-cells, CD8+ granulocytes and NK cells, highlights that Siglec-1 is a unique player in these essential processes.

Partitioned glioma heritability shows subtype-specific enrichment in immune cells

BACKGROUND

Epidemiological studies of adult glioma have identified genetic syndromes and 25 heritable risk loci that modify individual risk for glioma, as well increased risk in association with exposure to ionizing radiation and decreased risk in association with allergies. In this analysis, we assess whether there is a shared genome-wide genetic architecture between glioma and atopic/autoimmune diseases.

METHODS

Using summary statistics from a glioma genome-wide association studies (GWAS) meta-analysis, we identified significant enrichment for risk variants associated with gene expression changes in immune cell populations. We also estimated genetic correlations between glioma and autoimmune, atopic, and hematologic traits using linkage disequilibrium score regression (LDSC), which leverages genome-wide single-nucleotide polymorphism (SNP) associations and patterns of linkage disequilibrium.

RESULTS

Nominally significant negative correlations were observed for glioblastoma (GB) and primary biliary cirrhosis (rg = -0.26, P = .0228), and for non-GB gliomas and celiac disease (rg = -0.32, P = .0109). Our analyses implicate dendritic cells (GB pHM = 0.0306 and non-GB pHM = 0.0186) in mediating both GB and non-GB genetic predisposition, with GB-specific associations identified in natural killer (NK) cells (pHM = 0.0201) and stem cells (pHM = 0.0265).

CONCLUSIONS

This analysis identifies putative new associations between glioma and autoimmune conditions with genomic architecture that is inversely correlated with that of glioma and that T cells, NK cells, and myeloid cells are involved in mediating glioma predisposition. This provides further evidence that increased activation of the acquired immune system may modify individual susceptibility to glioma.

Paeoniflorin mitigates PBC-induced liver fibrosis by repressing NLRP3 formation

Purpose:

To delve into the influence of paeoniflorin (PA) on abating primary biliary cholangitis (PBC)-induced liver fibrosis and its causative role.

Methods:

Our team allocated the mice to control group, PA group, PBC group and PBC+PA group. We recorded the weight change of mice in each group. We used Masson staining for determining liver fibrosis, immunofluorescence staining for measuring tumor necrosis factor-α (TNF-α) expression, quantitative real-time polymerase chain reaction (qRT-PCR) for assaying related gene expression, as well as Western blot for testing related protein expression.

Results:

The weight of PBC model mice declined. Twenty-four weeks after modeling, the positive rate of anti-mitochondrial antibody-M2 (AMA-M2) in PBC mice reached 100%. Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), hydroxyproline (HYP), laminin (LN), procollagen type III (PC III), and malondialdehyde (MDA) contents saliently waxed (p<0.01). Meanwhile, superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activity patently waned (p<0.01). Liver fibrosis levels were flagrantly higher (p<0.01), and TNF-α, NOD-like receptor protein 3 (NLRP3), caspase-1, interleukin-18 (IL-18), and interleukin-1β (IL-1β) protein or gene expression were manifestly up-regulated (p<0.01). PA could restore the weight of PBC mice, strikingly restrain the positive expression of AMA-M2, and down-regulate serum ALP, ALT, AST, HYP, LN, PC III, MDA in PBC mice (p<0.01). PA could also significantly up-regulate SOD and GSH-px levels (p<0.01), down-regulate IL-1β, IL-18, caspase-1, NLRP3, and TNF-α protein or gene expression in PBC mice (p<0.01) and inhibit liver fibrosis levels (p<0.01).

Conclusions:

PA can reduce PBC-induced liver fibrosis in mice and may function by curbing the formation of NLRP3.

S-adenosyl-L-methionine (SAMe) halts the autoimmune response in patients with primary biliary cholangitis (PBC) via antioxidant and S-glutathionylation processes in cholangiocytes

S-adenosyl-L-methionine is an endogenous molecule with hepato-protective properties linked to redox regulation and methylation. Here, the potential therapeutic value of SAMe was tested in 17 patients with PBC, a cholestatic disease with autoimmune phenomena targeting small bile ducts. Nine patients responded to SAMe (SAMe responders) with increased serum protein S-glutathionylation. That posttranslational protein modification was associated with reduction of serum anti-mitochondrial autoantibodies (AMA-M2) titers and improvement of liver biochemistry. Clinically, SAMe responders were younger at diagnosis, had longer duration of the disease and lower level of serum S-glutathionylated proteins at entry. SAMe treatment was associated with negative correlation between protein S-glutathionylation and TNFα. Furthermore, AMA-M2 titers correlated positively with INFγ and FGF-19 while negatively with TGFβ. Additionally, cirrhotic PBC livers showed reduced levels of glutathionylated proteins, glutaredoxine-1 (Grx-1) and GSH synthase (GS). The effect of SAMe was also analyzed in vitro. In human cholangiocytes overexpressing miR-506, which induces PBC-like features, SAMe increased total protein S-glutathionylation and the level of γ-glutamylcysteine ligase (GCLC), whereas reduced Grx-1 level. Moreover, SAMe protected primary human cholangiocytes against mitochondrial oxidative stress induced by tBHQ (tert-Butylhydroquinone) via raising the level of Nrf2 and HO-1. Finally, SAMe reduced apoptosis (cleaved-caspase3) and PDC-E2 (antigen responsible of the AMA-M2) induced experimentally by glycochenodeoxycholic acid (GCDC). These data suggest that SAMe may inhibit autoimmune events in patients with PBC via its antioxidant and S-glutathionylation properties. These findings provide new insights into the molecular events promoting progression of PBC and suggest potential therapeutic application of SAMe in PBC.

Profiling of the pattern of the human TRB/IGH-CDR3 repertoire in primary biliary cholangitis patients

INTRODUCTION

Primary biliary cholangitis (PBC) is characterized by lymphocyte cell-induced immune destruction of cholangiole. However, the immunological characteristics of peripheral blood cells in PBC patients remain unknown. This study was designed to reveal the differences in the immunological characteristics between PBC patients and healthy adults.

METHODS

We performed high-throughput sequencing to determine the TRB-CDR3 and IGH-CDR3 repertoires of T and B cells in 19 healthy controls and 29 PBC patients. Different immunological characteristics, such as distinctive complementarity determining region 3 (TRB-CDR3) lengths, usage bias of V and J segments, and random nucleotide addition were identified in PBC and healthy control (HC) groups.

RESULTS

The diversity of TRB-CDR3 was significantly lower in the PBC group compared with the HC group. CDR3 and the N addition length distribution were significantly changed compared with the HC group. It appeared that the PBC group had more short N additions and the HC group had more long N additions in the TRB-CDR3 repertoire. The results also revealed a set of PBC-associated clonotypes compared with the HC group.

CONCLUSION

This study suggested that PBC is a complex autoimmune disease process with evidence of different TRB-CDR3 rearrangements compared with healthy adults that share IGH-CDR3 peptides with some autoimmune diseases. This new insight may contribute to a better understanding of the immune functions of PBC patients and benefit efficient applications of PBC diagnosis and treatments.

Thigh muscle MRI findings in myopathy associated with anti-mitochondrial antibody

INTRODUCTION

Myopathy associated with anti-mitochondrial antibody (AMA) has recently been characterized as a distinct type of idiopathic inflammatory myopathy. The purpose of this study is to evaluate the pattern of involvement in thigh muscles in AMA myopathy using MRI.

METHODS

Six patients with AMA myopathy were identified and their muscle MRI findings evaluated.

RESULTS

On thigh muscle MRI, all six patients showed high signal intensity with short-tau inversion recovery that reflected disease activity mostly in the adductor magnus, called a "cuneiform sign." Fatty degeneration was also prominent in the adductor magnus, as well as the semimembranosus muscles.

DISCUSSION

These characteristic changes on MRI contrast with those of other inflammatory myopathies. From these observations, we concluded that the localization pattern of the inflammatory changes in muscle MRI can contribute to the diagnosis of AMA myopathy.

A Practical Review of Primary Biliary Cholangitis for the Gastroenterologist

Primary biliary cholangitis (PBC) is an autoimmune chronic cholestatic liver disease characterized by biliary destruction and progressive intrahepatic cholestasis. PBC primarily affects women in their fifth or sixth decade of life. Although many patients are asymptomatic at presentation, fatigue, pruritus, sicca syndrome, and upper abdominal discomfort are common symptom manifestations. The etiology of PBC is thought to be related to interactions between underlying genetic predisposition and microbial and xenobiotic environmental triggers. The diagnosis is established in the setting of biochemical cholestasis and antimitochondrial or disease-specific antinuclear antibodies, with histologic evidence of nonsuppurative granulomatous cholangitis being supportive, but not required, to confirm disease. Care of patients with PBC encompasses therapies to slow disease progression, manage symptoms associated with cholestasis, and treat complications of advanced liver disease. Risk stratification based on simple clinical and laboratory parameters, either as binary response criteria and/or continuous models, helps identify the patients at greatest risk of poor outcome. First-line therapy to slow disease progression is ursodeoxycholic acid (UDCA), which is the mainstay of pharmacologic therapy for all patients with PBC. The only currently approved second-line option for patients who do not achieve adequate biochemical response or are intolerant to UDCA is the novel farnesoid X receptor agonist obeticholic acid. Off-label use of peroxisome proliferator-activated receptor agonists, including the fibrate class of drugs where available, is also recognized as an option for patients.

Primary biliary cholangitis: a comprehensive overview

Primary biliary cholangitis (PBC) is an autoimmune liver disease characterized by biliary destruction, progressive cholestasis, and potentially liver cirrhosis. Patients develop a well-orchestrated immune reaction, both innate and adaptive, against mitochondrial antigens that specifically targets intrahepatic biliary cells. A puzzling feature of PBC is that the immune attack is predominantly organ specific, although the mitochondrial autoantigens are found in all nucleated cells. The disease results from a combination of genetic and environmental risk factors; however, the exact pathogenesis remains unclear. Serologically, PBC is characterized by presence of antimitochondrial antibodies, which are present in 90-95 % of patients and are often detectable years before clinical signs appear. Like other complex disorders, PBC is heterogeneous in its presentation, symptomatology, disease progression, and response to therapy. A significant number of patients develop end-stage liver disease and eventually require liver transplantation. Recent studies from large international cohorts have better identified prognostic factors, suggesting a change in patient management based on risk stratification. Therapeutic options are changing. In this review we discuss data on the autoimmune responses and treatment of the disease.

MicroRNA-223 and microRNA-21 in peripheral blood B cells associated with progression of primary biliary cholangitis patients

Recently, there is ample evidence suggesting the important role of microRNAs (miRNAs) in autoimmune diseases via modulating B cells function. Primary biliary cholangitis (PBC) is a progressive immune-mediated liver disease with unclear pathogenic mechanism. Whether the miRNA in peripheral B cells of PBC involve the mechanisms of pathology and progression is not known. The present study explores miRNA deregulation in peripheral B-cell of PBC from stage I to IV and healthy controls. Peripheral B cells were obtained from 72 PBC patients (stage I, n = 17; stage II, n = 23; stage III, n = 16; stage IV, n = 16) and 15 healthy controls. Initially, in a discovery study, miRNA array analysis was performed, subsequently, in a validation study, quantitative PCR was used to investigate miRNA expression profile in B cells of PBS patients compared to healthy controls. Based on bioinformatics analysis, we identified the potential biological processes and significant signaling pathways affected by these microRNAs, and generated the microRNA–gene network. The discovery study identified 558 miRNAs differentially expressed in B cells of PBC patients compared to controls. Interestingly, among all differentially expressed miRNAs, hsa-miR-223-3p and hsa-miR-21-5p were the only miRNAs that showed consistent and significant down-regulation from stage I to stage III of PBC. Bioinformatics showed that potential target genes of both miRNAs involved in migration, cell differentiation, apoptosis, and signal transduction pathways. In conclusion, our results suggest that the expression profiles of miRNA in peripheral B cells of PBC patients are closely associated with the disease progression, especially the down-regulation of hsa-miR-223-3p and hsa-miR-21-5p. Taken together, our study offers novel perspectives on the role of miRNAs in PBC pathogenesis.

Rheumatic Disease Autoantibodies in Autoimmune Liver Diseases

BACKGROUND

Autoimmune liver diseases (ALDs) are known to be associated with systemic autoimmune rheumatic diseases (SARDs) and their autoantibodies. We aimed to study the prevalence of SARDs and related autoantibodies, as well as their prognostic implications in a group of patients with ALDs.

METHODS

This was a cross-sectional study. Sixty patients with ALDs (38.3% with autoimmune hepatitis; 11.7% with primary biliary cirrhosis; 25% with primary sclerosing cholangitis and 25% with overlap syndrome) were studied for the presence of SARDs and their autoantibodies.

RESULTS

There was autoimmune rheumatic disease in 20% of the studied sample. Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) were the commonest (11.6% and 5%, respectively). Antinuclear antibodies (ANAs) were present in 35% of the patients, followed by anti-Ro (20.0%); anti-nucleosome (18.3%); rheumatoid factor (10%) anti-CCP (8.3%); anti-RNP (8.3%); anti-ds-DNA (6.6%); anti-La (3.3%); anti-Sm (3.3%), anti-ribosomal P (3.3%). Anti-Ro (p = 0.0004), anti-La (p = 0.03), anti-RNP (p = 0.04) and anti-Sm (p = 0.03) were commonly found in patients with SARD, but not anti-DNA, anti-nucleosome and anti-ribosomal P. No differences were found in liver function tests regarding to the presence of autoantibodies.

CONCLUSIONS

There was a high prevalence of SARD and their autoantibodies in ALD patients. Anti-Ro, anti-La, anti-RNP and anti-Sm positivity points to an association with systemic autoimmune rheumatic diseases. The presence of autoantibodies was not related to liver function tests.

Anti-4-1BB monoclonal antibodies attenuate concanavalin A-induced immune-mediated liver injury in mice

Effective therapies for the treatment of immune-mediated liver disease are currently lacking. As a member of the tumor necrosis factor receptor superfamily, 4-1BB has a key role in T-cell activation and has been implicated in the development of autoimmune disorders. The purpose of the present study was to evaluate the potential therapeutic or preventive function of an anti-4-1BB monoclonal antibody (mAb) in a mouse model of concanavalin (Con) A-induced immune-mediated liver injury. A mouse model of immune-mediated liver injury was established by tail vein injection of Con A (20 mg/kg). 4-1BB mAb (100 µg), with or without methylprednisolone (MEP; 3 mg/kg), was intraperitoneally injected into the tail vein 2 h prior to or 2 h following Con A injection. Con A induced marked hepatocyte necrosis, significantly reduced CD 4⁺/CD25⁺ T-cell levels, and increased the serum levels of aspartate transaminase (AST) and alanine transaminase (ALT), in addition to the percentage of 4-1BB⁺ T-cells, compared with the control (all P<0.05). The administration of 4-1BB mAb prior to or following Con A injection was able to attenuate Con A-induced liver tissue damage and significantly reduce serum AST and ALT levels (P<0.05). A combination of MEP and 4-1BB mAb further reduced serum AST and ALT levels, compared with either treatment alone. In addition, administration of 4-1BB mAb and MEP alone or in combination significantly increased CD4⁺/CD25⁺ T-cell levels, compared with the control (P<0.05). These results suggested that 4-1BB mAb was able to attenuate liver injury and preserve liver function in a mouse model of Con A-induced immune-mediated liver injury by promoting the expansion of CD4⁺/CD25⁺ T-cells. Furthermore, a combination of 4-1BB mAb with MEP was associated with greater beneficial effects than either treatment alone. The clinical significance of 4-1BB mAb in immune-mediated liver disease remains to be elucidated in future studies.

Deletion of Galectin-3 Enhances Xenobiotic Induced Murine Primary Biliary Cholangitis by Facilitating Apoptosis of BECs and Release of Autoantigens

Galectin-3 (Gal-3) is a carbohydrate binding lectin, with multiple roles in inflammatory diseases and autoimmunity including its antiapoptotic effect on epithelial cells. In particular, increased expression of Gal-3 in epithelial cells is protective from apoptosis. Based on the thesis that apoptosis of biliary epithelial cells (BECs) is critical to the pathogenesis of Primary Biliary Cholangitis (PBC), we have analyzed the role of Gal-3 in the murine model of autoimmune cholangitis. We took advantage of Gal-3 knockout mice and immunized them with a mimotope of the major mitochondrial autoantigen of PBC, 2-octynoic acid (2-OA) coupled to BSA (2OA-BSA) and evaluated the natural history of subsequent disease, compared to control wild-type mice, by measuring levels of antibodies to PDC-E2, immunohistology of liver, and expression of Gal-3. We report herein that deletion of Gal-3 significantly exacerbates autoimmune cholangitis in these mice. This is manifested by increased periportal infiltrations, bile duct damage, granulomas and fibrosis. Interestingly, the BECs of Gal-3 knockout mice had a higher response to apoptotic stimuli and there were more pro-inflammatory lymphocytes and dendritic cells (DCs) in the livers of Gal-3 knockout mice. In conclusion, Gal-3 plays a protective role in the pathways that lead to the inflammatory destruction of biliary epithelial cells.

The Significance of Autoantibody Changes Over Time in Primary Biliary Cirrhosis

OBJECTIVES

In primary biliary cirrhosis (PBC), the antimitochondrial antibody is a cornerstone of diagnosis, but there have been conflicting reports about the correlation of autoantibodies with disease stage and prognosis. We studied whether autoantibody levels changed over time and sought correlations with clinical outcomes in a cohort of patients with PBC.

METHODS

We tested serial serum samples from patients with PBC at a research institution for several autoantibodies. Long-term clinical follow-up data were used to calculate the slopes (change over time) for autoantibodies, platelet count, Ishak fibrosis score, biopsy copper, and number of portal areas with bile ducts. An adverse clinical outcome was defined as hepatic decompensation, development of hepatocellular carcinoma, liver transplantation, or liver-related death. We performed linear or logistic regression or Fisher exact test as appropriate, adjusting for multiple comparisons.

RESULTS

Twenty-seven patients with PBC with 145 serum samples were studied. Of the cohort, 85% was white, 81% was female, and median follow-up time was 20 years. Of the autoantibodies tested, only sp100 changed significantly over time. The sp100 slope was inversely associated with the Ishak fibrosis slope (parameter estimate, -0.05; P = .0003).

CONCLUSIONS

While changes in most autoantibodies over time do not seem to correlate with clinical outcomes in PBC, a change in the sp100 autoantibody level may have prognostic utility with respect to the development of fibrosis on liver biopsy.

Primary biliary cirrhosis: Clinical and laboratory criteria for its diagnosis

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic granulomatous, and destructive inflammatory lesion of small intralobular and septal bile ducts, which is likely to be caused by an autoimmune mechanism with a the presence of serum antimitochondrial antibodies and a potential tendency to progress to cirrhosis. Despite the fact that the etiology of this disease has been unknown so far, there has been a considerable body of scientific evidence that can reveal the clinical and laboratory signs of PBC and the individual components of its pathogenesis and elaborate diagnostic criteria for the disease and its symptomatic therapy. Deficiencies in autoimmune tolerance are critical factors for the initiation and perpetuation of the disease. The purpose of this review is to summarize the data available in the literature and the author's findings on clinical and laboratory criteria for the diagnosis of PBC. This review describes the major clinical manifestations of the disease and the mechanisms of its development. It presents the immunological, biochemical, and morphological signs of PBC and their significance for its diagnosis. A great deal of novel scientific evidence for the problem of PBC has been accumulated. However, the inadequate efficiency of therapy for the disease lends impetus to the quest for its etiological factors and to further investigations of its pathogenetic mechanisms and, on this basis, to searches for new methods for its early diagnosis.

Expression of micro-RNAs in peripheral blood mononuclear cells from primary biliary cirrhosis patients

AIM

The aim of this study was to clarify the relationship between the expression of micro-RNAs (miRNAs) in peripheral blood mononuclear cells (PBMCs) and clinical presentation in patients with primary biliary cirrhosis (PBC).

METHODS

This study involved 58 patients with PBC, patients with control diseases including 25 patients with autoimmune hepatitis (AIH), six patients with PBC-AIH overlap syndrome, 23 patients with systemic lupus erythematosus (SLE), and 30 healthy controls. After miRNA was extracted from PBMCs, the expressions of miR-26a, miR-328, miR-299-5p, miR-146a, miR-155, miR-16, miR-132 and let7a were quantified by real-time PCR. The relationships between all miRNA expressions and clinical test parameters were also examined.

RESULTS

In PBC, the expressions of miR-155 and miR-146a were significantly increased compared to those in healthy controls. For miR-26a, miR-299-5p, miR-328 and let-7a, although no significant difference was observed in expression between patients and healthy controls, expressions were significantly increased in PBC compared to those in AIH. Expressions of miR-299-5p were significantly increased in PBC patients resistant to treatment with ursodeoxycholic acid (n = 18) compared to those in healthy controls. In the evaluation of the relationship between miRNA expression and clinical test parameters, significant and positive correlations were found for miR-299-5p with alkaline phosphatase, gamma-glutamyl transpeptidase, total bilirubin and immunoglobulin M levels.

CONCLUSION

The preset results suggest the existence of miRNAs that exhibit disease-specific increases in expression and miRNAs closely correlated with clinical test values in PBC. Further analyses of these miRNAs may contribute to the elucidation of the pathology of PBC.

Tumour necrosis factor alpha (TNF-α) genetic polymorphisms and the risk of autoimmune liver disease: a meta-analysis

Epidemiological studies have evaluated the association between tumour necrosis factor alpha (TNF-α)- 308G/A and (TNF-α)- 238G/A polymorphisms, and the risk of autoimmune liver disease (AILD), yet the results are conflicting. To derive a more precise estimation of the relationship, we performed this meta-analysis. A systematic review was conducted to identify all eligible studies of TNF-α polymorphisms and AILD risk. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association between the two TNF-α polymorphisms and AILD risk. A total of 15 eligible studies were identified. Overall, positive associations of -308G/A polymorphism with AILD risk were found (A vs G allele: OR =1.45, 95%CI = 1.13- 1.86; AA vs GG: OR = 2.74, 95%CI = 1.51- 4.96; GA vs GG: OR = 1.46, 95%CI = 1.11- 1.92;dominant model: OR = 1.57, 95%CI = 1.18- 2.10; recessive model: OR = 2.22, 95%CI = 1.31- 3.76). In subgroup analysis by ethnicity, a significantly higher risk was found in Caucasians. In subgroup analysis by AILD category, significant association was observed in autoimmune hepatitis and primary sclerosing cholangitis, especially in Caucasians. Patients carrying TNF-α-238A allele had a slightly decreased risk of developing AILD (OR = 0.65, 95%CI = 0.48- 0.87). However, we found both TNF-α polymorphisms were not associated with primary biliary cirrhosis risk, even in subgroup analysis. Our meta-analysis suggests that the TNF-α-308G/A and -238G/A polymorphisms may contribute to AILD susceptibility in Caucasians,especially for autoimmune hepatitis and primary sclerosing cholangitis. Nevertheless, we found both TNF-α polymorphisms were unlikely to be associated with the risk of primary biliary cirrhosis

Escherichia coli infection induces autoimmune cholangitis and anti-mitochondrial antibodies in non-obese diabetic (NOD).B6 (Idd10/Idd18) mice

Several epidemiological studies have demonstrated that patients with primary biliary cirrhosis (PBC) have a higher incidence of urinary tract infections (UTI) and there is significant homology of the immunodominant mitochondrial autoantigen, the E2 component of the pyruvate dehydrogenase complex (PDC-E2), between mammals and bacteria. Previous work has demonstrated that non-obese diabetic (NOD).B6 Idd10/Idd18 infected with Novosphingobium aromaticivorans developed liver lesions similar to human PBC. It was postulated that the biliary disease was dependent upon the presence of the unique N. aro glycosphingolipids in activating natural killer T (NK T) cells. To address this issue, we infected NOD.B6 Idd10/Idd18 mice with either Escherichia coli, N. aro or use of a phosphate-buffered saline (PBS) vehicle control and serially followed animals for the appearance of liver pathology and anti-mitochondrial autoantibodies (AMA). Of striking importance, the biliary disease of E. coli-infected mice was more severe than N. Aro-infected mice and the titre of AMA was higher in E. coli-infected mice. Furthermore, the immunopathology did not correlate with the ability of bacterial extracts to produce antigen-dependent activation of NK T cells. Our data suggest that the unique glycosphingolipids of N. aro are not required for the development of autoimmune cholangitis. Importantly, the data highlight the clinical significance of E. coli infection in a genetically susceptible host, and we suggest that the appearance of autoimmune cholangitis is dependent upon molecular mimicry. These data highlight that breach of tolerance to PDC-E2 is probably the first event in the natural history of PBC in genetically susceptible hosts.

Telomere dysfunction in peripheral blood mononuclear cells from patients with primary biliary cirrhosis

BACKGROUND

Chromosomal instability in peripheral blood mononuclear cells has a role in the onset of primary biliary cirrhosis. We hypothesized that patients with primary biliary cirrhosis may harbour telomere dysfunction, with consequent chromosomal instability and cellular senescence.

AIM

To evaluate the clinical significance of telomerase activity and telomere length in peripheral blood mononuclear cells from patients with primary biliary cirrhosis.

STUDY DESIGN

In this population-based case control study, 48 women with primary biliary cirrhosis (25 with cirrhosis), 12 with chronic hepatitis C matched by age and severity of disease, and 55 age-matched healthy women were identified. Mononuclear cells from the peripheral blood of patients and controls were isolated. Telomere length and telomerase activity were measured.

RESULTS

Telomere length and telomerase activity did not differ between cases (5.9 ± 1.5 kb) and controls (6.2 ± 1.4 kb, pc=0.164). Telomere shortening and advanced-stage disease strongly correlated with telomerase activity. Patients with advanced disease retained significantly less telomerase activity than those with early-stage disease (0.6 ± 0.9 OD vs. 1.5 ± 3.7 OD, p=0.03). Telomere loss correlated with age, suggesting premature cellular ageing in patients with primary biliary cirrhosis.

CONCLUSION

Our data strongly support the telomere hypothesis of human cirrhosis, indicating that telomere shortening and telomerase activity represent a molecular mechanism in the evolution of human cirrhosis in a selected population of patients.

Tracing environmental markers of autoimmunity: introducing the infectome

We recently introduced the concept of the infectome as a means of studying all infectious factors which contribute to the development of autoimmune disease. It forms the infectious part of the exposome, which collates all environmental factors contributing to the development of disease and studies the sum total of burden which leads to the loss of adaptive mechanisms in the body. These studies complement genome-wide association studies, which establish the genetic predisposition to disease. The infectome is a component which spans the whole life and may begin at the earliest stages right up to the time when the first symptoms manifest, and may thus contribute to the understanding of the pathogenesis of autoimmunity at the prodromal/asymptomatic stages. We provide practical examples and research tools as to how we can investigate disease-specific infectomes, using laboratory approaches employed from projects studying the “immunome” and “microbiome”. It is envisioned that an understanding of the infectome and the environmental factors that affect it will allow for earlier patient-specific intervention by clinicians, through the possible treatment of infectious agents as well as other compounding factors, and hence slowing or preventing disease development.

Vitamin D in autoimmune liver disease

The development of autoimmune disease is based on the interaction of genetic susceptibility and environmental causes. Environmental factors include infectious and non-infectious agents, with some of these factors being implicated in several autoimmune diseases. Vitamin D is now believed to play a role in the development (or prevention) of several autoimmune diseases, based on its immunomodulatory properties. As well, the increasing incidence of autoimmune disease as one moves away from the equator, may be due to the lack of sunlight, which is crucial for the maintenance of normal vitamin D levels. A deficiency in vitamin D levels or vitamin D receptors is commonly indicated in autoimmune diseases, with multiple sclerosis (MS) being one of the best-studied and well-known examples. However, the role of vitamin D in other autoimmune diseases is not well defined, including autoimmune liver diseases such as primary biliary cirrhosis, autoimmune hepatitis, and primary sclerosing cholangitis. This review will examine the role of vitamin D as an immunomodulator, followed by a comparison of vitamin D in MS versus autoimmune liver disease. From this comparison, it will become clear that vitamin D likely plays a role in the development of autoimmune liver disease, but this area requires further investigation.

The immunobiology and pathophysiology of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune disease characterized by clinical homogeneity among patients, an overwhelming female predominance, production of a multilineage immune response to mitochondrial autoantigens, inflammation of small bile ducts, and in some patients the development of fibrosis and cirrhosis. The targets in this disease are small bile ducts, and the prototypic serologic response includes antimitochondrial antibodies (AMAs). Several key observations have greatly advanced our understanding of PBC. First, the multilineage immune response, including AMAs, is directed at the E2 component of the 2-oxo-dehydrogenase pathway, particularly PDC-E2. Second, such autoantibodies may be identified years before the clinical diagnosis of disease. Third, the autoreactive T cell precursor frequency for both CD4 and CD8 cells is significantly higher in liver and regional lymph node than in blood, so the multilineage antimitochondrial response may be required for the development of this disease. Fourth, the apotope of biliary cells contains intact PDC-E2; this apotope, in a setting that includes granulocyte macrophage colony-stimulating factor-stimulated macrophages and AMAs, produces an intense proinflammatory response. Fifth, several mouse models of PBC highlight the importance of loss of tolerance to PDC-E2 as well as a critical role for the interleukin (IL)-12 signaling pathway. Finally, genome-wide association studies suggest an important role for the IL-12 pathway in disease susceptibility. Taken together, these findings have resulted in a better understanding of the mechanism for selective biliary cell destruction and have also suggested unique pathways for therapeutic intervention.

Autoantibodies in liver disease: important clues for the diagnosis, disease activity and prognosis

It has been well established that numerous kinds of autoantibodies have been detected in liver disease. Some kinds of autoantibodies may be helpful in the diagnosis of autoimmune liver diseases including autoimmune hepatitis, primary biliary cirrhosis or primary sclerosing cholangitis. However, these autoantibodies are present even in sera of patients with viral hepatitis, drug-induced hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease and hepatocelluar carcinoma as well as in sera of patients with autoimmune liver diseases. Other kinds of autoantibodies are recognized as predictive hallmarks for disease activity or prognosis in liver diseases. On the other hand, treatment with interferon initiates the production of several types of autoantibodies in patients with chronic hepatitis C virus infection. Some of autoantibodies induced by interferon may postulate the treatment outcome in those patients. Recent studies also revealed the close correlation between oxidative stress and the production of autoantibodies in liver diseases. This article primarily reviews the recent advances of autoantibodies in the liver diseases and discusses the clinical significance of these autoantibodies.

Environment and primary biliary cirrhosis: electrophilic drugs and the induction of AMA

Environmental stimulation is a major factor in the initiation and perpetuation of autoimmune diseases. We have addressed this issue and focused on primary biliary cirrhosis (PBC), an autoimmune disease of the liver. Immunologically, PBC is distinguished by immune mediated destruction of the intra hepatic bile ducts and the presence of high titer antimitochondrial autoantibodies (AMA) directed against a highly specific epitope within the lipoic acid binding domain of the pyruvate dehydrogenase E2 subunit (PDC-E2). We submit that the uniqueness of AMA epitope specificity and the conformational changes of the PDC-E2 lipoyl domain during physiological acyl transfer could be the lynchpin to the etiology of PBC and postulate that chemical xenobiotics modification of the lipoyl domain of PDC-E2 is sufficient to break self-tolerance, with subsequent production of AMA in patients with PBC. Indeed, using quantitative structure activity relationship (QSAR) analysis on a peptide-xenobiotic conjugate microarray platform, we have demonstrated that when the lipoyl domain of PDC-E2 was modified with specific synthetic small molecule lipoyl mimics, the ensuing structures displayed highly specific reactivity to PBC sera, at levels often higher than the native PDC-E2 molecule. Hereby, we discuss our recent QSAR analysis data on specific AMA reactivity against a focused panel of lipoic acid mimic in which the lipoyl di-sulfide bond are modified. Furthermore, data on the immunological characterization of antigen and Ig isotype specificities against one such lipoic acid mimic; 6,8-bis(acetylthio)octanoic acid (SAc), when compared with rPDC-E2, strongly support a xenobiotic etiology in PBC. This observation is of particular significance in that approximately one third of patients who have taken excessive acetaminophen (APAP) developed AMA with same specificity as patients with PBC, suggesting that the lipoic domain are a target of APAP electrophilic metabolites such as NAPQI. We submit that in genetically susceptible hosts, electrophilic modification of lipoic acid in PDC-E2 by acetaminophen or similar drugs can facilitate loss of tolerance and lead to the development of PBC.

Infectome: a platform to trace infectious triggers of autoimmunity

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects.

[Primary biliary cirrhosis-autoimmune hepatitis overlap syndrome in a patient with chronic hepatitis B infection]

We describe the case of a female patient with a previous diagnosis of primary biliary cirrhosis (PBC) and chronic hepatitis B in inactive phase who developed increased transaminase levels with no evidence of hepatitis B virus reactivation while receiving ursodeoxycholic acid treatment. A liver biopsy showed changes compatible with overlapping autoimmune hepatitis (AIH). Budesonide treatment achieved normalization of transaminase levels. We provide a review of PBC and AIH overlap syndrome and discuss the particular features of this case that led us to this diagnosis, as well as the treatment provided.

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 first-degree relatives (FDRs) of Greek PBC patients.

METHODS: The presence of antimitochondrial antibodies (AMA) and PBC-specific antinuclear antibodies (ANA) were determined using indirect immunofluorescence assays, dot-blot assays, and molecularly based enzyme-linked immunosorbent assays in 101 asymptomatic for liver-related symptoms FDRs of 44 PBC patients. 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 hepatitis-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 prevalence 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.

Cutting-edge issues in primary biliary cirrhosis

Several crucial issues remain open in our understanding of primary biliary cirrhosis (PBC), an autoimmune liver disease targeting the small- and medium-sized intrahepatic bile ducts. These issues include the high tissue specificity of the autoimmune injury despite the nontraditional autoantigens found in all mitochondria recognized by PBC-associated autoantibodies, the causes of the commonly observed pruritus, and the disease etiology per se. In all these fields, there has been recent interest secondary to the use of large-scale efforts (such as genome-wide association studies) that were previously considered poorly feasible in a rare disease such as PBC as well as other intuitions. Accordingly, there are now fascinating theories to explain the onset and severity of pruritus due to elevated autotaxin levels, the peculiar apoptotic features of bile duct cells to explain the tissue specificity, and genomic and epigenetic associations contributing to disease susceptibility. We have arbitrarily chosen these four aspects as the most promising in the PBC recent literature and will provide herein a discussion of the recent data and their potential implications.

Xenobiotics and autoimmunity: does acetaminophen cause primary biliary cirrhosis?

The serologic hallmark of primary biliary cirrhosis (PBC) is the presence of antimitochondrial autoantibodies (AMAs) directed against the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). The PBC-related autoepitope of PDC-E2 contains lipoic acid, and previous work has demonstrated that mimics of lipoic acid following immunization of mice lead to a PBC-like disease. Furthermore, approximately one-third of patients who have ingested excessive amounts of acetaminophen (paracetamol) develop AMA of the same specificity as patients with PBC. Quantitative structure-activity relationship (QSAR) data indicates that acetaminophen metabolites are particularly immunoreactive with AMA, and we submit that in genetically susceptible hosts, electrophilic modification of lipoic acid in PDC-E2 by acetaminophen or similar drugs can facilitate a loss of tolerance and lead to the development of PBC.

Autoimmune hepatitis type 2 associated with an unexpected and transient presence of primary biliary cirrhosis-specific antimitochondrial antibodies: a case study and review of the literature

BACKGROUND

Unlike other autoimmune liver diseases, primary biliary cirrhosis (PBC) has never been reported in early childhood, while type 2 autoimmune hepatitis (AIH) is eminently a paediatric disease.

CASE PRESENTATION

We describe a case of type 2 AIH with serological positivity for PBC-specific anti-mitochondrial antibodies (AMA) in a 3-year old girl. We found this observation intriguing as AMA and indeed an overlap with PBC are virtually absent in Type 2 AIH, a pediatric form of AIH which is distinct precisely because it is characterized by pathognomonic anti-liver kidney microsomal type 1 (LKM-1) showing a remarkable antigen-specificity directed against cytochrome P4502D6. We also review the literature in relation to AMA positivity in paediatric age and adolescence. In our case, the presence of AIH-2-specific anti-LKM-1 and PBC-specific AMA was confirmed by indirect immunofluorescence (IIF), and immunoblotting and ELISA based on recombinant mitochondrial antigens. The clinical, laboratory and histological features of the child are given in detail. Interestingly the mother was AMA positive without other features of PBC. The child was successfully treated with immunosuppression and five years after the original diagnosis is on a low dose of prednisolone and azathioprine, with no signs of relapse. Anti-LKM-1 antibodies are still present in low titres. AMA were detectable for the first 4 years after the diagnosis and disappeared later.

CONCLUSION

This is the first case report in the literature of AIH type 2 with an unexpected PBC-specific AMA positivity in a young child. Response to immunosuppressive treatment was satisfactory and similar to that described in AIH. A review of published reports on AMA positivity in paediatric age shows that the antibody may arise in the context of immunodeficiency and is variably associated with liver damage.

The role of natural killer (NK) and NK T cells in the loss of tolerance in murine primary biliary cirrhosis

One of the major obstacles in dissecting the mechanism of pathology in human primary biliary cirrhosis (PBC) has been the absence of animal models. Our laboratory has focused on a model in which mice, following immunization with a xenobiotic chemical mimic of the immunodominant autoepitope of the E2 component of pyruvate dehydrogenase complex (PDC-E2), develop autoimmune cholangitis. In particular, following immunization with 2-octynoic acid (a synthetic chemical mimic of lipoic acid-lysine located within the inner domain of PDC-E2) coupled to bovine serum albumin (BSA), several strains of mice develop typical anti-mitochondrial autoantibodies and portal inflammation. The role of innate immune effector cells, such as natural killer (NK) cells and that NK T cells, was studied in this model based on the hypothesis that early events during immunization play an important role in the breakdown of tolerance. We report herein that, following in-vivo depletion of NK and NK T cells, there is a marked suppression of anti-mitochondrial autoantibodies and cytokine production from autoreactive T cells. However, there was no change in the clinical pathology of portal inflammation compared to controls. These data support the hypothesis that there are probably multiple steps in the natural history of PBC, including a role of NK and NK T cells in initiating the breakdown of tolerance. However, the data suggest that adaptive autoimmune effector mechanisms are required for the progression of clinical disease.

The role of natural killer (NK) and NK T cells in the loss of tolerance in murine primary biliary cirrhosis

One of the major obstacles in dissecting the mechanism of pathology in human primary biliary cirrhosis (PBC) has been the absence of animal models. Our laboratory has focused on a model in which mice, following immunization with a xenobiotic chemical mimic of the immunodominant autoepitope of the E2 component of pyruvate dehydrogenase complex (PDC-E2), develop autoimmune cholangitis. In particular, following immunization with 2-octynoic acid (a synthetic chemical mimic of lipoic acid-lysine located within the inner domain of PDC-E2) coupled to bovine serum albumin (BSA), several strains of mice develop typical anti-mitochondrial autoantibodies and portal inflammation. The role of innate immune effector cells, such as natural killer (NK) cells and that NK T cells, was studied in this model based on the hypothesis that early events during immunization play an important role in the breakdown of tolerance. We report herein that, following in-vivo depletion of NK and NK T cells, there is a marked suppression of anti-mitochondrial autoantibodies and cytokine production from autoreactive T cells. However, there was no change in the clinical pathology of portal inflammation compared to controls. These data support the hypothesis that there are probably multiple steps in the natural history of PBC, including a role of NK and NK T cells in initiating the breakdown of tolerance. However, the data suggest that adaptive autoimmune effector mechanisms are required for the progression of clinical disease.

Involvement of commensal bacteria may lead to dysregulated inflammatory and autoimmune responses in a mouse model for chronic nonsuppurative destructive cholangitis

BACKGROUND

We previously reported a mouse model of primary biliary cirrhosis (PBC)-like chronic nonsuppurative destructive cholangitis (CNSDC), in which frequent injections of Streptococcus intermedius induced CNSDC and autoantibody production. The present study was performed to verify the model by examining 1) the reappearance of the PBC-like CNSDC after lymphocyte transfer from model to naïve mice, 2) the involvement of autophagy, and 3) the influence of the strain difference.

METHODS

Mice were inoculated with S. intermedius weekly for 8 weeks, then sacrificed to obtain samples. Spleen cells obtained from S. intermedius-inoculated mice were transferred to RAG2(-/-) mice.

RESULTS

CNSDC and elevated serum level of anti-gp210 titers were observed in S. intermedius-inoculated C57BL/6 mice, similar to the results of our previous report using BALB/c mice. Portal inflammation was induced in the livers of RAG2(-/-) mice by the transfer of spleen cells from S. intermedius-inoculated C57BL/6 mice. Among the inflammatory cells in the RAG2(-/-) mice, CD3-positive cells were predominant. Autophagosome-like structures were detected histologically, in the cytoplasm of infiltrated cells around the bile ducts in the livers of S. intermedius-inoculated both C57BL/6 and BALB/c mice. In S. intermedius-inoculated C3H/HeJ mice, inflammation in the portal area was less extensive than that in the hepatic parenchyma.

CONCLUSION

Bacterial component(s) and sequentially upregulated innate and acquired immune responses, accompanied by autophagy, might trigger CNSDC, via autoimmune mechanisms. Throughout the generation of bacteria-triggered PBC-like CNSDC, strain difference may influence the response to S. intermedius-inoculation in the liver.

Peripheral blood dendritic cells in alcoholic and autoimmune liver disorders

Little is known about effects of alcohol consumption on dendritic cell (DC) function and resultant immune response. However, quantitative and qualitative disturbances of DCs are speculated to be involved in alcohol-related as well as in other liver pathology. The present study aimed to evaluate changes in circulating DC subsets in alcoholic liver disease (N = 43), autoimmune hepatitis (N = 26) and primary biliary cirrhosis (N = 20). DCs isolated from the peripheral blood of recruited participants were stained with monoclonal antibodies against blood dendritic cell antigens (BDCAs) and estimated using the flow cytometry. Myeloid DCs were defined as BDCA-1(+)/CD19(-) cells, and lymphoid DCs as BDCA-2(+)/CD123(+) cells. Total numbers of circulating DCs in subjects with some liver diseases were markedly lower than in the healthy participants (p = 0.03). There was a significantly lower percentage of circulating BDCA-2(+)/CD123(+) (p = 0.02), and a tendency for the percentage of circulating BDCA-1(+)/CD19(-) cells to decrease in patients with liver diseases compared to the controls (p = 0.09). These results may suggest that decreased numbers of DCs may be responsible for reduced adaptive immune responses and increased susceptibility to infections and cancer development observed in patients exposed to alcohol. Moreover, numerical abnormalities of DCs may contribute to the breakdown of self-tolerance, a feature of autoimmune diseases.

Complete spectrum of AMA-M2 positive liver disease in north India

PURPOSE

This study describes the clinical, histological, and genetic profile of AMA-M2 positive liver disease in north India.

METHODS

Over 13.5 years, 11,221 patients suspected of AiLD (autoimmune liver disease) and negative for viral markers were screened for autoantibodies, ANA, ASMA, AMA, and LKM, by indirect immunofluorescence. Of these patients, 135 were AMA positive and 132 AMA-M2 positive. Clinical presentation of most of these patients was neither typical of AIH nor PBC. Sera of these patients were further tested for gp 210 and Sp 100. Fifty consecutive consenting patients were typed for HLA class II alleles DR and DQ and their clinical, biochemical, histology and genetic profiles were reviewed to characterize the disease spectrum in north India.

RESULTS

Only 22 of 50 patients had liver histology reports, and could be categorized on the basis of the criteria by Chazouillers et al. Of these 22, 13 had overlap syndrome, eight had classical PBC, whereas one had probable PBC. The remaining 28 could not be suitably categorized due to lack of liver histology. HLA DRB1*03 was found to be significantly associated with the disease in North Indian population.

CONCLUSION

This 13.5-year study demonstrates a definite rising annual incidence of AMA-M2-positive liver disease in north India. Complete evaluation of 50 patients indicated that a hepatitic variant of PBC (PBC-AIH), which is significantly associated with DRB1*03, predominates in north India.

Diagnosis of primary biliary cirrhosis

Primary biliary cirrhosis is the archetypal autoimmune liver disease, with the disease label describing a chronic granulomatous lymphocytic small bile duct cholangitis, which now most commonly presents asymptomatically and at an early pre-cirrhotic stage. Disease is more common than thought, with 1 in 1000 women over the age of 40 affected. Characteristic immunologic features of the disease assist clinicians in ready non-invasive diagnosis of patients, even if asymptomatic with only anicteric/cholestatic liver biochemical profiles. Over 90% of patients are anti-mitochondrial antibody positive, and for those negative, a significant proportion have highly specific anti-nuclear antibody profiles. Liver biopsy remains useful in certain settings where clarity is needed to confirm diagnosis, exclude alternative disease, and assess the relative contribution of PBC to other co-existent liver injury, and seeks to demonstrate in particular the classic bile duct lesions, as well as the degree of interface activity.

Primary biliary cirrhosis-related autoantibodies in a large cohort of italian patients with systemic sclerosis

OBJECTIVE

To analyze the prevalence, associations, and fine specificity of autoantibodies to primary biliary cirrhosis (PBC)-associated antigens (MIT3, Sp100, and gp210) in a cohort of Italian patients with systemic sclerosis (SSc).

METHODS

Sera samples from 201 patients with SSc were tested for antibodies to MIT3, gp210, and Sp100 by ELISA (the PBC screen). Anti-MIT3-positive sera were studied for IgG or IgA isotypes. All sera were analyzed by indirect immunofluorescence on HEp-2 cells and on rodent kidney/stomach/liver tissue sections in order to detect antinuclear and antimitochondrial antibodies (AMA). SSc was selected by American College of Rheumatology criteria and classified based on LeRoy's criteria.

RESULTS

Forty-three (21.4%) sera samples were positive for PBC screen antibodies. Anti-MIT3 antibodies were detected in 36 samples, anti-Sp100 in 5, and anti-gp210 in 1 sample. The other 3 PBC screen-positive samples showed no specificity for the single antigens. PBC screen-positive patients more frequently showed a limited cutaneous SSc subtype (p = 0.04), anticentromere antibodies (ACA; p = 0.0013), elevated alkaline phosphatase (ALP) (p < 0.0001), PBC (p = 0.002), and AMA (p = 0.008). Teleangiectasia and calcinosis were less frequent in this group of patients. IgG+IgA anti-MIT3-positive patients had higher prevalence of AMA (p = 0.0035), diagnosis of PBC (p = 0.014), and increased ALP (p = 0.039), all considered biochemical markers of severe liver disease.

CONCLUSION

PBC screen antibodies were detected in 20% of patients with SSc, strongly associated with ACA. ACA+/PBC screen+ patients had higher risk of developing PBC or elevation of ALP.

Towards systemic sclerosis and away from primary biliary cirrhosis: the case of PTPN22

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by immune-mediated destruction of the small and medium size intrahepatic bile ducts. PBC patients often have concomitant autoimmune diseases, which are most often autoimmune thyroid disease, as well as Sicca syndrome. Occasionally, some PBC patients will also have systemic sclerosis of the limited cutaneous type (lcSSc). Conversely, up to one-fourth of SSc patients are positive for antimitochondrial antibody, the serologic hallmark of PBC. It is also common for SSc patients to have concomitant autoimmune disease, which may include PBC in rare cases. This has led to speculation of shared environmental and/or genetic factors, which lead to the development of PBC in SSc patients and vice versa. Recent genetic studies have revealed associations with several genes in both SSc and PBC. PTPN22 is one gene that has been associated with SSc, but not with PBC. It may be argued that some SSc patients with a particular genotype, which shares genes found in both conditions may develop PBC. Likewise, particular genes such as PTPN22 may infer susceptibility to SSc alone. The presence of PTPN22 may also contribute to the development of SSc in PBC patients. The lack of a large number of overlapping genes may, in part, explain the relative rarity of PBC with SSc and vice versa. This review will examine the literature surrounding the genetic associations of PBC and SSc, and the role of PTPN22 in particular.

Primary biliary cirrhosis

Primary biliary cirrhosis is a chronic autoimmune inflammatory disease of the liver with a striking female preponderance. It has an insidious onset and typically affects middle-aged women. The disease manifests gradually with symptoms of fatigue, pruritis, and increased alkaline phosphatase levels on laboratory evaluation. The hallmark of the disease is the circulating antimitochondrial antibody. Histology is characterized by inflammation of the bile ducts, destruction of cholangiocytes, and subsequent cholestasis, progressing to biliary cirrhosis. The standard treatment for primary biliary cirrhosis is ursodeoxycholic acid, which improves survival, but the disease can still lead to cirrhosis and liver failure over decades.