Antimitochondrial Antibodies: from Bench to Bedside

Autoantibodies Against Dihydrolipoamide S-Acetyltransferase Are Not Associated With Immune-Mediated Neuropathies

OBJECTIVES

Dihydrolipoamide S-acetyltransferase (DLAT), the E2 component of the mitochondrial pyruvate dehydrogenase complex (PDC-E2), has recently been suggested to be a biomarker of chronic inflammatory demyelinating polyneuropathy (CIDP). It was particularly associated with sensory variants of CIDP. Antimitochondrial antibodies are important for the diagnosis of primary biliary cholangitis, but insofar, only 2 studies have reported an association with CIDP. Here, we aimed to validate these observations in a cohort of French patients with immune-mediated neuropathy.

METHODS

The positivity against PDC-E2/DLAT was examined using ELISA and confirmed using commercially available immuno-DOT and by indirect immunofluorescence on stomach, kidney, and liver sections.

RESULTS

None of the 20 healthy controls, 31 patients with Guillain-Barré syndrome, 102 patients with CIDP (including 24 patients with sensory CIDP), 26 patients with monoclonal gammopathy, 23 patients with Charcot-Marie-Tooth disease, or 20 patients with autoimmune nodopathy showed IgG against PDC-E2/DLAT.

DISCUSSION

PDC-E2/DLAT is accurately a target antigen in immune-mediated neuropathies.

Antinuclear Antibodies in Non-Rheumatic Diseases

Antinuclear antibodies (ANAs) are critical immunological markers commonly associated with various connective tissue diseases (CTDs). However, these autoantibodies are also detectable in healthy individuals, patients with non-rheumatic autoimmune diseases, those with viral infections, and subjects using specific medications (such as procainamide, hydralazine, and minocycline) that can lead to drug-induced ANA elevation. The standard method for ANA detection is indirect immunofluorescence, a process that requires precision and thoroughness as it assesses both titer and fluorescence patterns. Additionally, immunoblotting and enzyme-linked immunosorbent assay (ELISA) are recommended to identify specific ANAs precisely, highlighting the importance of precision in ANA detection. This review explores the advantages and limitations of current ANA detection methods. It also describes the clinical implications of ANA presence in non-rheumatic diseases, including autoimmune disorders, infectious conditions, non-autoimmune and non-infectious diseases, and autoimmune cutaneous diseases. The presence of elevated ANA titers in these contexts can complicate clinical decision-making, as the diagnostic value of ANA testing alone is limited in non-rheumatic conditions. However, despite these limitations, ANA remains a key component in diagnosing and prognosis systemic CTDs, as it can indicate disease activity, severity, and response to treatment, which is of utmost importance in rheumatology and internal medicine. This paper provides a comprehensive review of the role of ANA in non-rheumatic diseases. It focuses on ANA diagnostic and prognostic significance and offers valuable insights for clinical practice.

Probing the Effects of Multisite Mutations in the Lipoic Acid Region of the BCOADC-E2 Protein

Primary biliary cholangitis (PBC) is a chronic disease, the prevalence of which has been increasing in recent years. And the prevalence of patients who test negative with existing diagnostic techniques remains high. It was found that the antigenic BCOADC-E2 protein could detect patients with a negative original test. And experiments revealed that the lipoyl domain of BCOADC-E2 plays an important role. The present study was carried out to verify the necessity of maintaining the folding conformation of the lipoyl β-sheet of the protein in the lipoyl domain during the recognition of the BCOADC-E2 protein and the importance of the glutamic acid and isoleucine residues at position 4 and position 13, respectively. In order to search for a new pathway for the pre-detection of patients with PBC, firstly, the mutant proteins were subjected to an enzyme-linked immunosorbent assay (ELISA) with serum. Then, MTSSL spin tags were positioned at specific sites of the Cys mutant and reacted with serum samples from PBC patients and controls, and EPR spectroscopic data were measured. The multiple mutant proteins all reacted less specifically with the serum than the wild-type protein in the ELISA; the spectra measured for the pGEX-BCKD-E4A-I13A mutant were severely broadened, and the compactness at the conformational position of the lipoyl β-sheet structural conformation of the proteins of amino acids 4 and 13 remained unchanged. The EPR spectral data validate the importance of the glutamate and isoleucine residues at position 4 and position 13 and their necessity in the maintenance of the lipoyl β-sheet structural conformation of proteins in the lipoyl domain in anti-BCOADC-E2 recognition.

Molecular Mechanisms of Fibrosis in Cholestatic Liver Diseases and Regenerative Medicine-Based Therapies

The aim of this review is to explore the potential of new regenerative medicine approaches in the treatment of cholestatic liver fibrosis. Cholestatic liver diseases, such as primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and biliary atresia (BA), due to the accumulation of bile, often progress to liver fibrosis, cirrhosis, and liver failure. When the disease becomes severe enough to require liver transplantation. Deeply understanding the disease's progression and fibrosis formation is crucial for better diagnosis and treatment. Current liver fibrosis treatments mainly target the root causes and no direct treatment method in fibrosis itself. Recent advances in regenerative medicine offer a potential approach that may help find the ways to target fibrosis directly, offering hope for improved outcomes. We also summarize, analyze, and discuss the current state and benefits of regenerative medicine therapies such as mesenchymal stem cell (MSC) therapy, induced pluripotent stem cells (iPSCs), and organoid technology, which may help the treatment of cholestatic liver diseases. Focusing on the latest research may reveal new targets and enhance therapeutic efficacy, potentially leading to more effective management and even curative strategies for cholestatic liver diseases.

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.

Identification of microbial antigens in liver tissues involved in the pathogenesis of primary biliary cholangitis using 16S rRNA metagenome analysis

BACKGROUND

Multiple factors are involved in the pathogenesis of primary biliary cholangitis (PBC), a chronic cholestatic liver disease, characterized by intrahepatic cholangiopathy. In particular, studies have suggested that environmental factors such as the presence of granulomas in the portal vein region are important for the development of PBC. This study aimed to comprehensively analyze and identify foreign-derived antigens in PBC liver tissue to confirm their involvement in PBC pathogenesis.

METHODS

Portal areas and hepatocyte regions were selectively dissected from formalin-fixed paraffin-embedded PBC liver tissue samples using the microlaser method, followed by total DNA extraction. We then validated whether the bacterial strains identified through 16S rRNA metagenomic analysis were detected in PBC liver tissues.

RESULTS

The most frequently detected bacterial genera in the PBC liver tissue samples were Sphingomonas panacis, Providencia, and Cutibacterium. These bacterial genera were also detected in the other PBC samples. Validation for the detection of S. panacis, the most abundant genus, revealed polymerase chain reaction bands extracted from the portal areas of all samples. They were also more highly expressed than bands detected in the hepatocyte region.

CONCLUSION

S. panacis antigen was specifically detected in the portal areas of PBC liver tissues. The introduction of foreign-derived antigens into the liver as an environmental factor could be a possible mechanism for the development of PBC.

Combining Anti-Mitochondrial Antibodies, Anti-Histone, and PLA2/COX Biomarkers to Increase Their Diagnostic Accuracy for Autism Spectrum Disorders

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interaction and restricted and repetitive behaviors. Oxidative stress may be a critical link between mitochondrial dysfunction and ASD as reactive oxygen species (ROS) generated from pro-oxidant environmental toxicants and activated immune cells can result in mitochondrial failure. Recently, mitochondrial dysfunction, autoimmunity, and abnormal lipid mediators have been identified in multiple investigations as an acknowledged etiological mechanism of ASD that can be targeted for therapeutic intervention.

METHODS

The relationship between lipid mediator markers linked to inflammation induction, such as phospholipase A2/cyclooxygenase-2 (PLA2/Cox-2), and the mitochondrial dysfunction marker anti-mitochondrial antibodies (AMA-M2), and anti-histone autoantibodies in the etiology of ASD was investigated in this study using combined receiver operating characteristic (ROC) curve analyses. This study also sought to identify the linear combination for a given set of markers that optimizes the partial area under ROC curves. This study included 40 age- and sex-matched controls and 40 ASD youngsters. The plasma of both groups was tested for PLA2/COX-2, AMA-M2, and anti-histone autoantibodies' levels using ELISA kits. ROC curves and logistic regression models were used in the statistical analysis.

RESULTS

Using the integrated ROC curve analysis, a notable rise in the area under the curve was noticed. Additionally, the combined markers had markedly improved specificity and sensitivity.

CONCLUSIONS

The current study suggested that measuring the predictive value of selected biomarkers related to mitochondrial dysfunction, autoimmunity, and lipid metabolism in children with ASD using a ROC curve analysis could lead to a better understanding of the etiological mechanism of ASD as well as its relationship with metabolism.

Autoantibodes to GP210 are a metric for UDCA responses in primary biliary cholangitis

OBJECTIVES

Antibodies to gp210 and sp100 are specific and unique anti-nuclear autoantibodies (ANAs) associated with primary biliary cholangitis (PBC). Importantly the presence of anti-gp210 and anti-sp100 responses is indicative of poor clinical outcomes. However, the utility of measuring titers of these antibodies remains unclear.

MATERIALS AND METHODS

Using the in-house purified gp210 (HSA108-C18) and sp100 (amino acid position 296-386), we quantitatively measured serum autoantibodies to gp210 and sp100 using chemiluminescence immunoassay (CLIA) in a very large cohort of 390 patients with PBC, including 259 cases with no prior ursodesoxycholic acid (UDCA) treatment and 131 cases with UDCA treatment. We also analyzed serial changes in anti-gp210 and anti-sp100 levels in 245 sequential samples from 88 patients.

RESULTS

In our cross-sectional analysis, we detected anti-gp210 immunoglobulin G (IgG) and anti-sp100 IgG autoantibodies in 129 out of 390 (33.1%) and 80 out of 390 (20.5%) PBC patients, respectively. Multivariate analysis revealed that serum IgG (st.β = 0.35, P = 0.003) and gamma-glutamyltransferase (GGT) (st.β = 0.23, P = 0.042) levels at baseline were independently associated with anti-gp210 concentrations. In serial testing, we observed significant fluctuations in anti-gp210 antibody levels. These fluctuations reflected responsiveness to UDCA therapy, particularly in anti-gp210-positive patients with initially lower concentrations in the stages of disease.

CONCLUSIONS

Our study reflects that quantitative changes of anti-gp210 antibody are indicative of UDCA responses. There is a great need for newer metrics in PBC and we suggest that a more detailed and longer study of these unique ANAs is warranted.

ChIP-seq analysis found IL21R, a target gene of GTF2I-the susceptibility gene for primary biliary cholangitis in Chinese Han

AIMS

Aimed to identify a new susceptibility gene associated with primary biliary cholangitis (PBC) in Chinese Han and investigate the possible mechanism of that gene in PBC.

METHODS

A total of 466 PBC and 694 healthy controls (HC) were included in our study, and genotyping GTF2I gene variants by Sequenom. CD19 + B cells were isolated for Chromatin immunoprecipitation sequencing (ChIP-seq). Additionally, MEME-ChIP was utilized to perform searches for known motifs and de novo motif discovery. The GTF2I ChIP-seq of hematopoietic cell line (K562) results were obtained from ENCODE (GSE176987, GSE177691). The Genomic HyperBrowser was used to determine overlap and hierarchal clustering between ours and ENCODE datasets.

RESULTS

The frequency of the rs117026326 variant T allele was significantly higher in PBC patients than that in HC (20.26% compared with 13.89%, Pc = 1.09E-04). Furthermore, we observed an elevated proportion of GTF2I binding site located in the upstream and 5' UTR of genes in PBC in comparison with HC. Additionally, an in-depth analysis of IL21R region revealed that GTF2I might bind to the IL21R promoter to regulate the expression of the IL21R, with four peaks of GTF2I binding sites, including three increased binding sites in upstream, one increased binding site in 5' UTR. Motif analysis by MEME-ChIP uncovered five significant motifs. A significant overlap between our ChIP and GSE176987, GSE17769 were found by the Genomic HyperBroswer.

CONCLUSIONS

Our study confirmed that GTF2I was associated with PBC in Chinese Han. Furthermore, our gene function analysis indicated that IL21R may be the target gene regulated by GTF2I.

Genetic link between primary biliary cholangitis and connective tissue diseases in European populations: A two-sample Mendelian randomization study

BACKGROUND

An association between primary biliary cholangitis (PBC) and connective tissue diseases (CTDs) [rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), systemic sclerosis (SSc)] has been found in observational studies. However, the direction causality is unclear. The aim of this study was to assess the causality between PBC and CTDs and to promote early screening, pre-emptive therapy, and accurate stratification.

METHODS

A two-sample Mendelian randomization (MR) analysis was performed to assess the causal relationship between PBC [Genome-Wide Association Study (GWAS) meta-analysis, 8021 cases/16498 controls], and SLE (GWAS meta-analysis, 8021 cases/16489 controls), RA(FinnGen, 6236 cases/14727 controls), SS(FinnGen, 2495 cases/365533 controls), SSc (FinnGen, 302 cases/213145 controls). Inverse variance weighting (IVW) was used as the primary analysis method, supplemented by four sensitivity analyses to assess the robustness of the results.

RESULTS

The IVW revealed that genetically predicted PBC increased the risk of SLE [odd's ratio (OR) = 1.43, 95% confidence interval (CI) 1.30-1.58, P < 0.001]), RA (OR = 1.09, 95%CI1.04-1.14, P<0.001), and SS (OR = 1.18, 95%CI1.12-1.24, P<0.001), but not that of SSc. In addition, no association was observed between CTDs as an exposure and PBC. Sensitivity analyses did not reveal horizontal pleiotropy.

CONCLUSIONS

Our study provided new genetic evidence for a causal relationship between PBC and CTDs. PBC increased the risk of SLE, RA, and SS. Our findings highlighted the importance of active screening and intervention for CTDs in patients with PBC.

A break in mitochondrial endosymbiosis as a basis for inflammatory diseases

Mitochondria retain bacterial traits due to their endosymbiotic origin, but host cells do not recognize them as foreign because the organelles are sequestered. However, the regulated release of mitochondrial factors into the cytosol can trigger cell death, innate immunity and inflammation. This selective breakdown in the 2-billion-year-old endosymbiotic relationship enables mitochondria to act as intracellular signalling hubs. Mitochondrial signals include proteins, nucleic acids, phospholipids, metabolites and reactive oxygen species, which have many modes of release from mitochondria, and of decoding in the cytosol and nucleus. Because these mitochondrial signals probably contribute to the homeostatic role of inflammation, dysregulation of these processes may lead to autoimmune and inflammatory diseases. A potential reason for the increased incidence of these diseases may be changes in mitochondrial function and signalling in response to such recent phenomena as obesity, dietary changes and other environmental factors. Focusing on the mixed heritage of mitochondria therefore leads to predictions for future insights, research paths and therapeutic opportunities. Thus, whereas mitochondria can be considered 'the enemy within' the cell, evolution has used this strained relationship in intriguing ways, with increasing evidence pointing to the recent failure of endosymbiosis being critical for the pathogenesis of inflammatory diseases.

Primary biliary cirrhosis and psoriasis: a two-sample Mendelian randomization study

Background

Primary biliary cirrhosis (PBC) and psoriasis are frequently observed to co-occur in clinical settings. However, the causal associations and underlying mechanisms between PBC and psoriasis remain poorly defined.

Methods

In this study, we conducted bidirectional MR analysis to explore the causal relationship between PBC and psoriasis using four MR methods: inverse-variance weighted, MR-Egger regression, weighted median, and weighted mode. Sensitivity analyses were carried out, employing different models and testing methods for comparison to assess the influence of heterogeneity and pleiotropy on our findings and to confirm the robustness of these results.

Results

A causal relationship between the risk of PBC and psoriasis was identified, as confirmed by IVW analysis (OR: 1.081, 95%CI: 1.028~1.137, P<0.05). The other three MR methods also produced similar results. However, psoriasis did not have a causal effect on PBC risk (OR: 1.022, 95%CI: 0.935~1.118, P>0.05). The intercept of MR-Egger regression was 0.0013 (P>0.05), indicating that genetic pleiotropy did not influence the results. Additionally, the leave-one-out analysis demonstrated the robustness of our MR findings.

Conclusion

This study reveals a causal relationship between PBC and psoriasis, with PBC increasing the risk of psoriasis, but not the reverse. This potential causal relationship offers a new perspective on the etiology of PBC.

Evaluation strategy of anti-mitochondrial antibodies M2-negative: the role of multiplex rodent tissues and related clinical implications

Indirect immunofluorescence on HEp-2 cell line (HEp-2-IIF) remains "gold standard" method for the detection of antinuclear antibodies (ANA). ANA is an operative definition, showing the possibility of autoantibodies (Aab) to bind nuclear, and cytoplasmic antigens. One of the major examples is represented by anti-mitochondrial antibodies (AMAs), which target proteins of the inner and outer mitochondrial membranes, located into the cytoplasm. The standard IIF on rat kidney/stomach/liver tissue sections, with the combined use of other commercial assays, may all be used in ordinary lab life to validate the AC-21 pattern on Hep-2 cells. The routine lab experience teaches that commercial kits cannot always be detected and define specific AMAs. In these cases the literature proposes the use of other homemade assays to detect AMAs as immunoprecipitation (IP) and Western blot (IP-WB). However, using IP or IP-WB is difficult to apply in a routine laboratory, because of numerous cases to process and the related troubles. Where find confirmation of the AC-21 pattern if line-immunoblot and other routine methods (ELISA, CLIA/FEIA assays) fail? We review AC-21 AMA-like sera from our patients (year 2022) and propose a revised diagnostic algorithm based on the combined use of IIF on Hep-2 cells, line immunoblot and IIF on rodent tissue as a third line method. We demonstrated that, particularly in cases where the second level test was unsuccessful, the application of IFI on rodent tissues became indispensable to verify the existence of AMAs.

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.

Antimitochondrial antibody-negative primary biliary cirrhosis with secondary Sjogren syndrome: a case report

Introduction and importance

Primary biliary cholangitis (PBC) is a rare immune-mediated liver disease characterized by the destruction of intrahepatic bile ducts and a positive antimitochondrial antibody (AMA), which is considered a serological hallmark for the diagnosis. Rarely, AMA can be absent/nondetectable in a few cases and is referred to as 'AMA-negative'.

Case presentation

The authors present such an uncommon case of AMA-negative PBC in a 39-year-female with Sjogren's syndrome who presented with fatigue, pruritus, and dry eyes.

Clinical discussion

Previously published studies state that approximately only about 5% of patients with PBC are 'AMA-negative'. For patients negative for AMA, the diagnosis has to be based on typical pathological features of this disease. Once a diagnosis of PBC is established, regardless of whether it is positive or negative for AMAs, ursodeoxycholic acid is a widely accepted treatment.

Conclusion

The presence/absence of AMAs is associated with similar clinical, biochemical, and histopathological characteristics in PBC. The identification of AMAs alone should not impact the diagnosis or treatment of PBC.

Philadelphia chromosome-negative myeloproliferative chronic neoplasms: is clonal hematopoiesis the main determinant of autoimmune and cardio-vascular manifestations?

In this article, we reviewed the possible mechanisms linking the clonal hematopoiesis of indeterminate potential (CHIP) to chronic myeloproliferative neoplasms (MPNs), autoimmune diseases (ADs), and cardiovascular diseases (CADs). CHIP is characterized by the presence of clonal mutations with an allelic frequency >2% in the peripheral blood without dysplasia, overt hematological neoplasms, or abnormalities in blood cell count. The prevalence may reach 20% of elderly healthy individuals and is considered a risk factor for myelodysplastic neoplasms and acute leukemia. In MPNs, CHIP is often associated with mutations such as JAK2V617F or DNMT3A, TET2, or ASXL1, which exhibit a 12.1- and 1.7-2-fold increase in CADs. Specifically, JAK2-mutated cells produce excessive cytokines and reactive oxygen species, leading to proinflammatory modifications in the bone marrow microenvironment. Consequently, the likelihood of experiencing thrombosis is influenced by the variant allele frequency (VAF) of the JAK2V617F mutation, which also appears to be correlated with anti-endothelial cell antibodies that sustain thrombosis. However, DNMT3A mutations induce pro-inflammatory T-cell polarization and activate the inflammasome complex, while TET2 downregulation leads to endothelial cell autophagy and inflammatory factor upregulation. As a result, in patients with TET2 and DNMT3A-related CHIP, the inflammasome hyperactivation represents a potential cause of CADs. CHIP also occurs in patients with large and small vessel vasculitis, while ADs are more frequently associated with MPNs. In these diseases, monocytes and neutrophils play a key role in the formation of neutrophil extracellular trap (NET) as well as anti-endothelial cell antibodies, resulting in a final procoagulant effect. ADs, such as systemic lupus erythematosus, psoriasis, and arthritis, are also characterized by an overexpression of the Rho-associated coiled-coil containing protein kinase 2 (ROCK2), a serine/threonine kinase that can hyperactivate the JAK-STAT pathway. Interestingly, hyperactivation of ROCK2 has also been observed in myeloid malignancies, where it promotes the growth and survival of leukemic cells. In summary, the presence of CHIP, with or without neoplasia, can be associated with autoimmune manifestations and thrombosis. In the presence of these manifestations, it is necessary to consider a "disease-modifying therapy" that may either reduce the clonal burden or inhibit the clonally activated JAK pathway.

The clinical value of the monocyte to high-density lipoprotein cholesterol ratio and alkaline phosphatase-to-platelet ratio in primary biliary cholangitis

This study aimed to evaluate the clinical value of the monocyte to high-density lipoprotein cholesterol ratio (MHR) and alkaline phosphatase-to-platelet ratio (APPR) in the diagnosis and prognosis of primary biliary cholangitis (PBC). Clinical and laboratory data were retrospectively collected and analyzed from 92 PBC patients, 92 patients with autoimmune hepatitis (AIH), 120 patients with chronic hepatitis B (CHB) and 124 healthy controls (HCs). We compared the levels of MHR and APPR among the groups with PBC, AIH, CHB and HCs, and analyzed the correlations between MHR and APPR with laboratory indices including aspartate aminotransferase platelet ratio index, fibrosis index based on 4 factors, and Mayo score in PBC. Receiver operating characteristic curves were used to analyze the diagnostic performance of MHR and APPR for PBC, AIH, and CHB, respectively. MHR and APPR were significantly increased in PBC group than that in AIH, CHB and HCs groups (each P < .05). MHR and APPR were significantly higher in Child class B|C than that in class A in PBC patients. (P < .01, P < .05, respectively). MHR and APPR were positively related to the Mayo score [R = 0.508 (P < .001), R = 0.295 (P = .008), respectively]. The area under the receiver operating characteristic curves of MHR and APPR in diagnosing PBC were 0.764 (95% confidence interval [CI]: 0.699-0.821, P < .001) and 0.952 (95% CI: 0.915-0.977, P < .001), respectively, and the area under the curve of the combination of both was 0.974 (95% CI: 0.941-0.991, P < .001). MHR and APPR may prove to be useful prognostic biomarkers for PBC, and the combination of MHR and APPR have some clinical diagnostic value of PBC.

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.

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 self-directed 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.

Value of the HFA-PEFF diagnostic algorithms for heart failure with preserved ejection fraction to the inflammatory myopathy population

OBJECTIVES

The HFA-PEFF score has been validated to hold great diagnostic and prognostic utility for heart failure with preserved ejection fraction (HFpEF). Idiopathic inflammatory myopathy (IIM) is recognized as one of the potential etiologies underlying HFpEF. Here, we intended to investigate the real prevalence of HFpEF in IIM via the HFA-PEFF score and explore the prognostic value of this score.

METHODS

Two hundred twenty IIM patients were enrolled for assessment. The cohort was divided into low, intermediate and high tertiles of the HFA-PEFF score. Spearman's correlation analysis was used to explore the association between the score and disease activity. Chi-square test was applied to investigate the distribution discrepancy of HFA-PEFF tertiles among patients with different myositis-specific antibodies (MSAs) or myositis-associated antibodies (MAAs). Univariate and multivariate ordinal regression analyses were performed to screen risk factors for high HFA-PEFF scores. Survival curves were obtained using the Kaplan-Meier method and log-rank tests.

RESULTS

In total, 79 (35.9%), 107 (48.6%) and 34 (15.5%) patients were rated low, intermediate and high probability of HFpEF, respectively. The HFA-PEFF score correlated well with disease activity. Patients with positive AMA-M2 scored higher in the HFA-PEFF score (p = 0.011). During follow-up, patients with positive AMA-M2 or anti-SRP antibody developed an inclination towards concentric hypertrophy on echocardiography. Additionally, palpitation symptom, AMA-M2 positivity and elevated serum levels of LDH, cTnI were independent risk factors for high HFA-PEFF scores. Finally, a high-tertile HFA-PEFF score was related to lower overall survival rate (p < 0.001). Patients with positive AMA-M2 had poorer outcomes (p = 0.002).

CONCLUSION

HFpEF was prevailing in IIM patients according to the HFA-PEFF score. The HFA-PEFF score correlated well with disease activity and held significant prognostic value. Patients with AMA-M2 antibody were prone to have poor outcomes.

Laboratory risk factors for coexistent primary biliary cholangitis in patients with Sjögren's syndrome: a retrospective study

BACKGROUND

Limited research exists on the laboratory characteristics of coexistent primary biliary cholangitis (PBC) and Sjögren's syndrome (SS). This study aimed to investigate the laboratory risk factors for the coexistence of PBC in patients with SS.

METHODS

Eighty-two patients with coexistent SS and PBC (median age 52.50 years) and 82 age- and sex-matched SS controls were retrospectively enrolled between July 2015 and July 2021. The clinical and laboratory characteristics of the two groups were compared. Laboratory risk factors for the coexistence of PBC in patients with SS were analyzed using logistic regression analysis.

RESULTS

Both groups had a similar prevalence of hypertension, diabetes, thyroid disease, and interstitial lung disease. Compared with the SS group, patients in the SS + PBC group had higher levels of liver enzymes, immunoglobulins M (IgM), G2, and G3 (P < 0.05). The percentage of patients with an antinuclear antibody (ANA) titre > 1:10000 in the SS + PBC group was 56.1%, higher than that in the SS group (19.5%, P < 0.05). Additionally, cytoplasmic, centromeric, and nuclear membranous patterns of ANA and positive anti-centromere antibody (ACA) were observed more frequently in the SS + PBC group (P < 0.05). Logistic regression analysis showed that elevated IgM levels, high ANA titre, cytoplasmic pattern, and ACA were independent risk factors for PBC coexistence in SS.

CONCLUSIONS

In addition to established risk factors, elevated IgM levels, positive ACA, and high ANA titre with cytoplasmic pattern provide clues to clinicians for the early screening and diagnosis of PBC in patients with SS.

Non-organ-specific autoantibodies with unspecific patterns are a frequent para-infectious feature of chronic hepatitis D

Infections with hepatotropic viruses are associated with various immune phenomena. Hepatitis D virus (HDV) causes the most severe form of viral hepatitis. However, few recent data are available on non-disease-specific and non-organ-specific antibody (NOSA) titers and immunoglobulin G (IgG) levels in chronic hepatitis D (CHD) patients. Here, we examined the NOSA titers and IgG levels of 40 patients with CHD and different disease courses and compared them to 70 patients with chronic hepatitis B (CHB) infection. 43% of CHD patients had previously undergone treatment with pegylated interferon-α (IFN-α). The antibody display of 46 untreated patients diagnosed with autoimmune hepatitis (AIH) was used as a reference. The frequency of elevated NOSA titers (CHD 69% vs. CHB 43%, p < 0.01), and the median IgG levels (CHD 16.9 g/L vs. CHB 12.7 g/L, p < 0.01) were significantly higher in CHD patients than in patients with CHB, and highest in patients with AIH (96%, 19.5 g/L). Also, the antinuclear antibody pattern was homogeneous in many patients with AIH and unspecific in patients with viral hepatitis. Additionally, f-actin autoantibodies were only detectable in patients with AIH (39% of SMA). In CHD patients, IgG levels correlated with higher HDV viral loads, transaminases, and liver stiffness values. IgG levels and NOSA were similar in CHD patients irrespective of a previous IFN-α treatment. In summary, autoantibodies with an unspecific pattern are frequently detected in CHD patients with unclear clinical relevance.

Detection of M2-Type Anti-Mitochondrial Autoantibodies against Specific Subunits in the Diagnosis of Primary Biliary Cholangitis in Patients with Discordant Results

BACKGROUND

M2-type anti-mitochondrial autoantibodies are considered the hallmark of primary biliary cholangitis and are directed mainly against the E2 subunits of the 2-oxo acid dehydrogenase complex enzymes (PDC, BCOADC and OGDC). The aim of this study was to determine whether a Dot-blot that includes these E2 subunits separately could confirm the results of methods with non-separated subunits in patients with low positive or discordant results between techniques.

METHODS

Sera of 24 patients with low positive or discordant results and of 10 patients with clear positive results by non-separated subunits methods were analyzed by Dot-blot with separated subunits.

RESULTS

Autoantibodies against E2 subunits of PDC, BCOADC or OGDC were detected in all patients, except in one case from the low positive or discordant results group, by Dot-blot with separated subunits.

CONCLUSIONS

It would be advisable to use methods that include the three E2 subunits, and a Dot-blot with separated subunits could confirm doubtful cases by non-separated assays.

The risk of development of primary biliary cholangitis among incidental antimitochondrial M2 antibody-positive patients

Background and Aim

This study investigated the risk of the development of primary biliary cholangitis (PBC) in individuals who were incidentally identified as having positive antimitochondrial antibodies (AMA)-M2.

Materials and Methods

We retrospectively reviewed extractable nuclear antibody (ENA) panel test results to identify the incidental AMA-M2-positive patients. Patients who filled the diagnostic criteria for PBC were excluded. AMA-M2-positive patients were further evaluated by physical examination, liver biochemistry, liver ultrasonography, and transient elastography (TE) and were also closely followed.

Results

We included 48 (n=45, 93% female) individuals with a median age of 49 (range: 20-69) years. The median follow-up duration was 27 months (range: 9-42) after the detection of AMA-M2. Thirty-three (69%) patients had concomitant autoimmune/inflammatory disorders. Twenty-eight (58%) individuals showed seropositivity for ANA, and 21 had (43%) positive AMA. Fifteen (31%) patients developed typical PBC according to the international PBC diagnostic criteria during the follow-up, and five of them (18%) had significant fibrosis (≥8.2 kPA) by TE at the time of PBC diagnosis.

Conclusion

Two-thirds of the incidental AMA-M2-positive patients developed typical features of PBC after a median 27-month follow-up. Our results suggest that AMA-M2 patients should be closely followed up to detect the late development of PBC.

Selected Aspects of the Intricate Background of Immune-Related Cholangiopathies-A Critical Overview

Primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are rare immune-related cholangiopathies with still poorly explained pathogenesis. Although triggers of chronic inflammation with subsequent fibrosis that affect cholangiocytes leading to obliteration of bile ducts and conversion to liver cirrhosis are unclear, both disorders are regarded to be multifactorial. Different factors can contribute to the development of hepatocellular injury in the course of progressive cholestasis, including (1) body accumulation of bile acids and their toxicity, (2) decreased food intake and nutrient absorption, (3) gut microbiota transformation, and (4) reorganized host metabolism. Growing evidence suggests that intestinal microbiome composition not only can be altered by liver dysfunction, but in turn, it actively impacts hepatic conditions. In this review, we highlight the role of key factors such as the gut-liver axis, intestinal barrier integrity, bile acid synthesis and circulation, and microbiome composition, which seem to be strongly related to PBC and PSC outcome. Emerging treatments and future therapeutic strategies are also presented.

Using two-step cluster analysis to classify inpatients with primary biliary cholangitis based on autoantibodies: A real-world retrospective study of 537 patients in China

Background

A variety of autoantibodies have been detected in primary biliary cholangitis (PBC), while the presence of autoantibody clusters and their clinical significance have not been fully understood. We aimed at defining autoantibody clusters and to better understand the clinical features and prognosis of PBC patients based on autoantibody clusters under real-world conditions.

Methods

We retrospectively analyzed 788 inpatients with PBC evaluated between October 2008 and July 2019, and included 537 patients. Nineteen autoantibodies which were measured routinely were investigated for cluster analysis. Two-step clustering, Kaplan-Meier survival, and Cox regression analyses were used.

Results

Five clusters were defined. A cluster of antinuclear antibodies (ANA) and anti-gp210 positive patients were identified with a high rate of cirrhosis at baseline and low survival rate; a cluster of ANA, anti-centromere antibodies (ACA) and/or anti-CENP-B female dominant patients with older disease onset, low level of platelet count at baseline, high rate of hepatic decompensation, and low survival rate was also characterized; and another cluster of anti-mitochondrial antibodies (AMA) and/or AMA-M2, anti-Ro52 and a high rate of anti-gp210 positive patients were identified with a high proportion of male patients and low survival rate. A subgroup of patients with anti-SSA and/or anti-SSB coexists with SjS was also identified; patients with only AMA and/or AMA-M2-positive with a benign clinical outcome and relatively high complication of non-alcoholic fatty liver disease (NAFLD) were also identified. Only anti-gp210 was considered as a significant predictor for poor outcomes especially in patients with cirrhosis.

Conclusion

Clustering methods allow the identification of distinct autoantibody profiles of PBC that form clinical subsets and can be useful for personalized approaches to diagnosis, clinical management, and the prediction of clinical outcomes. Anti-gp210 was the strongest predictive factor for poor outcomes especially in PBC patients with cirrhosis under real-world conditions.

Mitochondrial Myopathy in a 21-Year-Old Man Presenting With Bilateral Lower Extremity Weakness and Swelling

Bilateral lower extremity weakness and swelling can have several causes. Although often underdiagnosed, mitochondrial myopathy is more prevalent in the general population than more commonly suspected diseases, such as Guillain-Barre syndrome. The clinical manifestations of mitochondrial disease can be broadly classified into 3 categories: chronic progressive external ophthalmoplegia, skeletal muscle-central nervous system syndromes, or pure myopathy. Cardiac abnormalities occur in 30% to 32% of cases, mostly in the form of hypertrophic cardiomyopathy, dilated cardiomyopathy, or conduction abnormalities. We report a case of a 21-year-old student who developed bilateral lower limb weakness, pain, and swelling diagnosed with mitochondrial myopathy on muscle biopsy. Initial laboratory tests revealed elevated creatinine kinase, brain natriuretic peptide, troponin, myoglobin, and lactic acid and reduced serum bicarbonate. Cardiac workup revealed systolic heart failure with a reduced ejection fraction. Endomyocardial biopsy revealed punctate foci of lymphocytic myocarditis. However, cardiac magnetic resonance imaging did not reveal either myocarditis or an infiltrative cardiac disease. An extensive autoimmune and infection work-up was negative. A muscle biopsy from the patient's rectus femoris revealed scattered ragged-blue fibers (stained with NADH dehydrogenase), scattered ragged-red fibers on modified Gomori trichrome stain, and cytochrome-c oxidase negative fibers with increased perimysial and endomysial connective tissue, consistent with active and chronic primary mitochondrial myopathy. The patient was treated successfully with furosemide, metoprolol, and methylprednisolone. Adult-onset mitochondrial myopathy is a rare clinical disorder, and our experience stresses the importance of using an inter-disciplinary team approach to diagnose uncommon clinical disorders with widely variable multisystem involvement.

A New Role of NAP1L1 in Megakaryocytes and Human Platelets

Platelets (PLTs) are anucleate and considered incapable of nuclear functions. Contrastingly, nuclear proteins were detected in human PLTs. For most of these proteins, it is unclear if nuclear or alternatively assigned functions are performed, a question we wanted to address for nuclear assembly protein 1like 1 (NAP1L1). Using a wide array of molecular methods, including RNAseq, co-IP, overexpression and functional assays, we explored expression pattern and functionality of NAP1L1 in PLTs, and CD34⁺-derived megakaryocytes (MKs). NAP1L1 is expressed in PLTs and MKs. Co-IP experiments revealed that dihydrolipolylysine-residue acetyltransferase (DLAT encoded protein PDC-E2, ODP2) dynamically interacts with NAP1L1. PDC-E2 is part of the mitochondrial pyruvate-dehydrogenase (PDH) multi-enzyme complex, playing a crucial role in maintaining cellular respiration, and promoting ATP-synthesis via the respiratory chain. Since altered mitochondrial function is a hallmark of infectious syndromes, we analyzed PDH activity in PLTs from septic patients demonstrating increased activity, paralleling NAP1L1 expression levels. MKs PDH activity decreased following an LPS-challenge. Furthermore, overexpression of NAP1L1 significantly altered the ability of MKs to form proplatelet extensions, diminishing thrombopoiesis. These results indicate that NAP1L1 performs in other than nucleosome-assembly functions in PTLs and MKs, binding a key mitochondrial protein as a potential chaperone, and gatekeeper, influencing PDH activity and thrombopoiesis.

The future risk of primary biliary cholangitis (PBC) is low among patients with incidental anti-mitochondrial antibodies but without baseline PBC

Anti-mitochondrial autoantibodies (AMAs) are highly specific for the diagnosis of primary biliary cholangitis (PBC) but are also occasionally found in other diseases. In the present study, we evaluated the incidence of and predictors for PBC development in AMA-positive patients with other liver or non-liver diseases at baseline. In this retrospective study, we screened patients who tested positive for AMA and/or anti-mitochondrial M2 antibody (AMA-M2) at Beijing Friendship Hospital, Capital Medical University, from October 2005 to January 2017. They were categorized by their diagnosis at the baseline as patients with PBC or non-PBC cases. We followed up on the non-PBC cases through telephone interviews and reviewing of medical records to obtain laboratory results and clinical outcomes. In total, 139 patients were AMA-positive but did not fulfill the diagnostic criteria of PBC at baseline, including 51 patients with non-PBC liver diseases and 88 cases with non-liver diseases. The titers of AMA-M2, alkaline phosphatase, gamma-glutamyl transpeptidase, and immunoglobulin M were significantly higher in patients with PBC compared to those with non-PBC liver diseases and non-liver diseases. After a median follow-up of 4.6 (interquartile range: 2.4-7.6) years, 4.3% (6 of 139) developed PBC, with an accumulative 5-year incidence rate of 4.2%. None of the patients with non-PBC liver diseases developed PBC, whereas the 5-year incidence rate of PBC was 7.8% among 88 patients with non-liver diseases. Lower alanine aminotransferase and higher immunoglobulin M were independent predictors for developing PBC. Conclusion: Our results suggest a low risk of developing PBC over time in AMA-positive patients with other liver and non-liver diseases.

Alteration of Mitochondrial DNA Copy Number and Increased Expression Levels of Mitochondrial Dynamics-Related Genes in Sjögren's Syndrome

Sjögren's syndrome (SS) is a chronic autoimmune multifactorial disease characterized by inflammation and lymphocytic infiltration of the exocrine glands. Several studies have highlighted the involvement of oxidative stress in this pathology, suggesting that it could induce mitochondrial dysfunctions. Mitochondria could have a role in inflammatory and immune processes. Since the mitochondrial DNA (mtDNA) copy number could change in response to physiological or environmental stimuli, this study aimed to evaluate possible alterations in the mtDNA copy number in SS. We have analyzed the amount of mtDNA in the peripheral blood of 74 SS patients and 61 healthy controls by qPCR. Then, since mitochondrial fusion and fission play a crucial role in maintaining the number of mitochondria, we investigated the expression variability of the genes most commonly involved in mitochondrial dynamics in a subgroup of SS patients and healthy controls. Interestingly, we observed a highly significant decrease in mtDNA copies in the SS patients compared to healthy controls (p = 1.44 × 10^-12). Expression levels of mitochondrial fission factor (MFF), mitofusin-1 (MFN1), and mitochondrial transcription factor A (TFAM) genes were analyzed, showing a statistically significant increase in the expression of MFF (p = 0.003) and TFAM (p = 0.022) in the SS patients compared to healthy controls. These results give further insight into the possible involvement of mitochondrial dysfunctions in SS disease.

Linking Human Betaretrovirus with Autoimmunity and Liver Disease in Patients with Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune liver disease characterized by the production of diagnostic antimitochondrial antibodies (AMA) reactive to the pyruvate dehydrogenase complex. A human betaretrovirus (HBRV) resembling mouse mammary tumor virus has been characterized in patients with PBC. However, linking the viral infection with the disease is not a straight-forward process because PBC is a complex multifactorial disease influenced by genetic, hormonal, autoimmune, environmental, and other factors. Currently, PBC is assumed to have an autoimmune etiology, but the evidence is lacking to support this conjecture. In this review, we describe different approaches connecting HBRV with PBC. Initially, we used co-cultivation of HBRV with biliary epithelial cells to trigger the PBC-specific phenotype with cell surface expression of cryptic mitochondrial autoantigens linked with antimitochondrial antibody expression. Subsequently, we have derived layers of proof to support the role of betaretrovirus infection in mouse models of autoimmune biliary disease with spontaneous AMA production and in patients with PBC. Using Hill’s criteria, we provide an overview of how betaretrovirus infection may trigger autoimmunity and propagate biliary disease. Ultimately, the demonstration that disease can be cured with antiviral therapy may sway the argument toward an infectious disease etiology in an analogous fashion that was used to link H. pylori with peptic ulcer disease.

Interplay between Mast Cells and Regulatory T Cells in Immune-Mediated Cholangiopathies

Immune-mediated cholangiopathies are characterised by the destruction of small and large bile ducts causing bile acid stasis, which leads to subsequent inflammation, fibrosis, and eventual cirrhosis of the liver tissue. A breakdown of peripheral hepatic immune tolerance is a key feature of these diseases. Regulatory T cells (Tregs) are a major anti-inflammatory immune cell subset, and their quantities and functional capacity are impaired in autoimmune liver diseases. Tregs can undergo phenotypic reprogramming towards pro-inflammatory Th1 and Th17 profiles. The inflamed hepatic microenvironment influences and can impede normal Treg suppressive functions. Mast cell (MC) infiltration increases during liver inflammation, and active MCs have been shown to be an important source of pro-inflammatory mediators, thus driving pathogenesis. By influencing the microenvironment, MCs can indirectly manipulate Treg functions and inhibit their suppressive and proliferative activity. In addition, direct cell-to-cell interactions have been identified between MCs and Tregs. It is critical to consider the effects of MCs on the inflammatory milieu of the liver and their influence on Treg functions. This review will focus on the roles and crosstalk of Tregs and MCs during autoimmune cholangiopathy pathogenesis progression.