Novel Anti-Hexokinase 1 Antibodies Are Associated With Poor Prognosis in Patients With Primary Biliary Cholangitis

Serum autoantibodies against hexokinase 1 manifest secondary to diabetic macular edema onset

AIMS

Autoantibodies against hexokinase 1 (HK1) were recently proposed to be associated with diabetic macular edema (DME). We hypothesized that anti-HK1 autoantibodies can be used as DME markers and to predict DME onset.

MATERIALS AND METHODS

Serum from patients with 1) DME, 2) diabetes mellitus (DM), 3) allergies or autoimmunities, and 4) control subjects was tested for anti-HK1 and anti-hexokinase 2 (HK2) autoantibodies by immunoblotting. Patients with DM were prospectively followed for up to nine years, and the association of anti-HK1 antibodies with new-onset DME was evaluated. The vitreous humor was also tested for autoantibodies.

RESULTS

Among patients with DME, 32 % were positive for anti-HK1 autoantibodies (42 % of those with underlying type 1 DM and 31 % of those with underlying type 2 DM), and 12 % were positive for anti-HK2 autoantibodies, with only partial overlap of these two groups of patients. Anti-HK1 positive were also 7 % of patients with DM, 6 % of patients with allergies and autoimmunities, and 3 % of control subjects. The latter three groups were anti-HK2 negative. Only one of seven patients with DM who were initially anti-HK1 positive developed DME.

CONCLUSIONS

Anti-HK1 autoantibodies can be used as DME markers but fail to predict DME onset.

Autoimmune Markers in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease. The most common antibody associated with PBC is the anti-mitochondrial antibody (AMA), present in 90% to 95% of patients. For patients who are AMA-negative, novel biomarkers, such as antinuclear antibody-specific antibodies Sp100 and gp210 and anti-kelch-like-12 and anti-hexokinase-1 antibodies, may further aid in the diagnosis of PBC. Several laboratory methods, including immunofluorescence, enzyme-linked immunosorbent assay, immunoblotting, and bead-based assays, exist to evaluate for the presence of antibodies. This article describes various methods used to evaluate antibodies as well as describe the antibodies present in PBC.

Antimitochondrial antibody associated with liver cirrhosis in patients with primary biliary cholangitis

Antimitochondrial antibody (AMA) serves as a serological marker for diagnosing primary biliary cholangitis (PBC). However, the association between AMA and prognosis for PBC patients remains unclear. The objective of this study was to investigate the relationship between AMA and cirrhosis in PBC patients. This retrospective study enrolled 225 PBC patients, including 127 with liver cirrhosis and 98 without cirrhosis. AMA was tested by indirect immunofluorescence (IIF) with rat kidney as the substrate. AMA-M2 and M2-3E were detected by line immunoassay (LIA). The overall positivity rate for AMA detection in PBC patients was 80.9%. The positivity rates of IIF-AMA, AMA-M2, and M2-3E were significantly higher in patients with liver cirrhosis than in those without cirrhosis (73.2% vs. 52.0%, 74.0% vs. 51.0%, and 80.3% vs. 60.2%, respectively). In multivariate logistic regression, IIF-AMA (OR: 3.05, 95% CI: 1.59-5.87), AMA-M2 (OR: 3.11, 95% CI: 1.61-6.01), and M2-3E (OR: 3.29, 95% CI: 1.63-6.66) remained significantly associated with an increased incidence of liver cirrhosis. Moreover, in multinomial logistic regression, IIF-AMA (compensated cirrhosis, OR: 3.55, 95% CI: 1.49-8.44; decompensated cirrhosis, OR: 2.86, 95% CI: 1.32-6.18), AMA-M2 (compensated cirrhosis, OR: 4.74, 95% CI: 1.94-11.58; decompensated cirrhosis, OR: 2.51, 95% CI: 1.19-5.33), and M2-3E (compensated cirrhosis, OR: 4.92, 95% CI: 1.74-13.96; decompensated cirrhosis, OR: 2.91, 95% CI: 1.28-6.64) were all found to be associated with different stages of liver cirrhosis. AMA was found to be associated with the occurrence of liver cirrhosis in PBC patients. Additionally, AMA was also related to different stages of liver cirrhosis, including compensated and decompensated cirrhosis.

Regulatory T-cell deficiency leads to features of autoimmune liver disease overlap syndrome in scurfy mice

Introduction

Scurfy mice have a complete deficiency of functional regulatory T cells (Treg) due to a frameshift mutation in the Foxp3 gene. The impaired immune homeostasis results in a lethal lymphoproliferative disorder affecting multiple organs, including the liver. The autoimmune pathology in scurfy mice is in part accompanied by autoantibodies such as antinuclear antibodies (ANA). ANA are serological hallmarks of several autoimmune disorders including autoimmune liver diseases (AILD). However, the underlying pathogenesis and the role of Treg in AILD remain to be elucidated. The present study therefore aimed to characterize the liver disease in scurfy mice.

Methods

Sera from scurfy mice were screened for ANA by indirect immunofluorescence assay (IFA) and tested for a wide range of AILD-associated autoantibodies by enzyme-linked immunosorbent assay, line immunoassay, and addressable laser bead immunoassay. CD4+ T cells of scurfy mice were transferred into T cell-deficient B6/nude mice. Monoclonal autoantibodies from scurfy mice and recipient B6/nude mice were tested for ANA by IFA. Liver tissue of scurfy mice was analyzed by conventional histology. Collagen deposition in scurfy liver was quantified via hepatic hydroxyproline content. Real-time quantitative PCR was used to determine fibrosis-related hepatic gene expression. Hepatic immune cells were differentiated by flow cytometry.

Results

All scurfy mice produced ANA. AILD-associated autoantibodies, predominantly antimitochondrial antibodies, were detected at significantly higher levels in scurfy sera. CD4+ T cells from scurfy mice were sufficient to induce anti-dsDNA autoantibodies and ANA with an AILD-related nuclear envelope staining pattern. Liver histology revealed portal inflammation with bile duct damage and proliferation, as in primary biliary cholangitis (PBC), and interface hepatitis with portal-parenchymal necroinflammation, as found in autoimmune hepatitis (AIH). In scurfy liver, TNFα and fibrosis-related transcripts including Col1a1, Timp1, Acta2, Mmp2, and Mmp9 were upregulated. The level of proinflammatory monocytic macrophages (Ly-6Chi) was increased, while M2-type macrophages (CD206+) were downregulated compared to wildtype controls. Despite severe hepatic inflammation, fibrosis did not develop within 25 days, which is close to the lifespan of scurfy mice.

Discussion

Our findings suggest that Treg-deficient scurfy mice spontaneously develop clinical, serological, and immunopathological characteristics of AILD with overlapping features of PBC and AIH.

Risk Stratification in Primary Biliary Cholangitis

Primary Biliary Cholangitis (PBC) is a chronic cholestatic liver disease with a heterogeneous presentation, symptomatology, disease progression, and response to therapy. The current risk stratification assessment, aimed at identifying patients with a higher risk of disease progression, encompasses an in-depth analysis of demographic data, clinical and laboratory findings, antibody profiles, and the evaluation of liver fibrosis using both invasive and noninvasive techniques. Treatment response scores after one year of therapy remain to date a major factor influencing the prognosis of PBC patients. While the initial therapeutic approach with ursodeoxycholic acid (UDCA) is universally applied, new second-line treatment options have recently emerged, with many others under investigation. Consequently, the prevailing one-size-fits-all approach is poised to be supplanted by tailored strategies, ensuring high-risk patients receive the most appropriate treatment regimen from diagnosis. This will require the development of a risk prediction model to assess, at the time of diagnosis, the course, outcome, and response to first and additional treatments of PBC patients. This manuscript provides a comprehensive overview of the current and emerging tools used for risk stratification in PBC and speculates on how these developments might shape the disease landscape in the near future.

Correlation between individual autoantibodies and clinical features in primary biliary cholangitis: results of a retrospective longitudinal study

BACKGROUND AND AIMS

Primary biliary cholangitis (PBC) is an immune-mediated liver disease. The immunological profile seems to relate to clinical prognosis. This study aims to determine the role of autoantibodies in the course of liver disease and in the response to ursodeoxycholic acid.

METHODS

Between January 2016 and December 2020, 143 patients with PBC who underwent immunological liver profile evaluation were enrolled. All data were extracted retrospectively from electronic clinical records. Chi-square test, Fisher's exact test and Mann-Whitney test were used to evaluate the relationship between autoantibodies and biochemical parameters, clinical outcomes and therapeutic response scores. A significance level of 0.05 was used.

RESULTS

Antimitochondrial antibodies were present in 91.6%, antiglycoprotein-210 antibody (anti-gp210) in 18.2% and anti-Sp100 in 19.6% of patients. The incidence of liver-related death was higher in patients with autoimmune hepatitis variants. The occurrence of cirrhosis or portal hypertension was not linked to the presence of any of the autoantibodies tested. No relationship was found with the probability of dying or being transplanted. Patients with anti-Sp100 antibodies had higher baseline levels of aspartate aminotransferase and alanine aminotransferase and lower immunoglobulin M levels. Patients with anti-gp210 were more likely to have a lower median transplant-free survival rate and higher median risk of liver transplant or liver-related death using the GLOBE and UK-PBC scores.

CONCLUSION

Our findings confirm a strong association between anti-gp210 antibodies and a worse outcome. The association between anti-Sp100 and hepatic lesions requires further elucidation.

Role of autoantibodies in the clinical management of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease characterized by immune-driven destruction of small intrahepatic bile ducts leading a proportion of patients to hepatic failure over the years. Diagnosis at early stages in concert with ursodeoxycholic acid treatment has been linked with prevention of disease progression in the majority of cases. Diagnosis of PBC in a patient with cholestasis relies on the detection of disease-specific autoantibodies, including anti-mitochondrial antibodies, and disease-specific anti-nuclear antibodies targeting sp100 and gp210. These autoantibodies assist the diagnosis of the disease, and are amongst few autoantibodies the presence of which is included in the diagnostic criteria of the disease. They have also become important tools evaluating disease prognosis. Herein, we summarize existing data on detection of PBC-related autoantibodies and their clinical significance. Moreover, we provide insight on novel autoantibodies and their possible prognostic role in PBC patients.

Presence of anti-gp210 or anti-sp100 antibodies in AMA-positive patients may help support a diagnosis of primary biliary cholangitis

BACKGROUND

Anti-mitochondrial antibody (AMA) positivity is not always associated with primary biliary cholangitis (PBC). We aimed to determine the additional value of anti-sp100 or anti-gp210 antibody in AMA-positive patients for PBC.

METHODS

Patients (n = 190) and healthy donors (n = 50) were evaluated for AMA, anti-gp210 and anti-sp100 antibodies by ELISA. Antibody frequencies in cohorts and performance characteristics in some patients categorized as 'definitive-', 'probable-', and 'no PBC' were determined following review of their charts.

RESULTS

Of the patients (n = 190), 38.4% were AMA-positive (n = 73) and 61.6% AMA-negative (n = 117). Frequency of anti-sp100 or anti-gp210 antibody was 17.8%, 2.6%, and 0% in AMA-positive, AMA-negative and healthy controls, respectively. Clinical data was available for 63 of 73 AMA-positive patients with 28.6%, 22.2%, and 49.2% categorized as definite, probable, and no PBC, respectively. Patients with definite PBC had higher mean levels of AMA and frequencies of sp100 or gp210 antibody compared to other groups. Sensitivities were low (anti-sp100: 18.8% and anti-gp210: 16.7%) with specificities above 98.0% for both.

CONCLUSION

AMA-positive patients positive for anti-sp100 or anti-gp210 antibody were more likely to have a diagnosis of definite or probable PBC than those with AMA alone. Use of all tests is likely to improve characterization of patients at-risk for PBC.

Autoantibodies in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is a chronic immune-mediated liver disease characterized by a lymphocytic cholangitis, with subsequent cholestasis, progressive liver fibrosis, and ultimately complications arising from end-stage liver disease. Testing for autoantibodies is important in the diagnosis of PBC, as well as stratifying prognosis. This review focuses on the role of autoantibodies in the diagnosis of PBC, as well as the relationship between autoantibodies with pathophysiology and prognostication, along with a discussion regarding novel and other related disease autoantibodies.

Working Algorithms and Detection Methods of Autoantibodies in Autoimmune Liver Disease: A Nationwide Study

Autoantibody detection is the cornerstone of autoimmune liver diseases (AILD) diagnosis. Standardisation of working algorithms among autoimmunity laboratories, as well as being aware of the sensitivity and specificity of various commercial techniques in daily practice, are still necessary. The aim of this nationwide study is to report the results of the 2020 Autoimmunity Workshop organised by the Autoimmunity Group of the Spanish Society of Immunology and to provide useful information to clinicians and laboratory specialists to improve the management of autoantibody detection in AILD diagnoses. Serum samples from 17 patients with liver diseases were provided by the organisers of the 2020 Autoimmunity Workshop and were subsequently analysed by the 40 participating laboratories. Each laboratory used different techniques for the detection of autoantibodies in each patients’ serum sample, according to their working algorithm. Thus, almost 680 total complete patient reports were obtained, and the number of results from different autoantibody detection techniques was >3000. Up to eight different working algorithms were employed, including indirect immunofluorescence assays (IFA) and antigen-specific techniques (AgST). The IFA of HEp-2 cells was more sensitive than IFA of rat triple tissue for the study of anti-nuclear autoantibodies (ANA) associated with AILD. The IFA of a human neutrophil study for the analysis of anti-neutrophil cytoplasmic autoantibodies was not carried out systemically in all patients, or by all laboratories. AgSTs were the most sensitive methods for the detection of anti-smooth muscle/F-actin, soluble liver antigen, liver cytosol-1, M2-mitochondrial autoantibodies, and ANA associated with primary biliary cholangitis. The main differences in AMA detection were due to patients with autoantibodies against the non-dominant epitope of pyruvate dehydrogenase complex. Given that they are complementary, IFA and AgST should be performed in parallel. If there is high suspicion of AILD, AgST should always be performed.

Rates of decompensation, hepatocellular carcinoma and mortality in AMA-negative primary biliary cholangitis cirrhosis

BACKGROUND

The natural history of patients with anti-mitochondrial antibody (AMA)-negative Primary Biliary Cholangitis (PBC) cirrhosis has not been well defined, with prior studies showing discordant results. Furthermore, most studies of AMA-negative PBC have limited numbers of patients with cirrhosis and liver-related outcomes.

METHODS

We investigated the association of AMA-negative PBC and the development of death, liver-related death, decompensation and hepatocellular carcinoma (HCC), in a large cohort of predominantly male patients with PBC cirrhosis assembled from the Veterans Health Administration.

RESULTS

In a cohort of 521 patients with PBC cirrhosis (65 AMA-negative) with a total follow-up of 2504.3 person-years (PY) from cirrhosis diagnosis, patients with AMA-negative PBC were younger and more likely to be black but had similar rates of UDCA response. AMA-negative PBC cirrhosis was associated with similar unadjusted rates of liver-related death (4.6 vs 5.9 per 100 PY, P = .44), overall death (7.7 vs 9.6 per 100 PY, P = .31), decompensation (7.3 vs 5.1 per 100 PY, P = .12) and HCC (0.6 vs 1.0 per 100 PY, P = .63) to AMA-positive PBC. After adjusting for confounders, AMA-negative PBC cirrhosis was associated with similar rates of liver-related death (sub-Hazard Ratio [sHR] 1.27, 95% CI 0.71-2.28, P = .42, death [sHR] 1.24, 95% CI 0.81-1.90, P = .32), decompensation (sHR 1.05, 95% CI 0.56-1.98, P = .87) and HCC (sHR 0.48, 95% CI 0.11-2.10, P = .33) to AMA-positive patients.

CONCLUSION

In a cohort of predominantly male patients, AMA-negative PBC cirrhosis was associated with similar rates of overall or liver-related death, HCC or decompensation compared with AMA-positive disease.

Clinical impact of antibodies to Sp100 on a bacterial infection in patients with primary biliary cholangitis

BACKGROUND

A specific antinuclear antibody for primary biliary cholangitis (PBC) is anti-Sp100, which was recognized as a serological marker of concurrent urinary tract infection. We sought to determine the clinical characteristics of PBC patients who had anti-Sp100.

PATIENTS AND METHODS

Fifty-one patients with PBC and 10 healthy controls (HCs) were enrolled. Anti-Sp100 were determined with an ELISA method. Lipopolysaccharide-binding protein (LBP) was measured as a serological hallmark for bacterial infection. The correlations of anti-Sp100 with demographic, laboratory, and pathological parameters were investigated.

RESULTS

Six of the 51 (11.8%) PBC patients had anti-Sp100, whereas none of the HCs did. There was no significant difference in the frequency of antimitochondrial antibodies (AMAs) between PBC patients with and without anti-Sp100 (67% vs. 82%, p = 0.5839). Biochemical and immunological parameters were not associated with the emergence of anti-Sp100 in these patients. The clinical stage by Scheuer classification was not correlated with the existence of anti-Sp100. No significant difference in the serum LBP levels was found between PBC patients with and without anti-Sp-100, although serum LBP levels were significantly higher in PBC patients with anti-Sp100 than in HCs (8.30 ± 2.24 ng/ml, vs. 5.12 ± 2.48 ng/ml, p = 0.0022). The frequency of granuloma formation was higher in the liver specimens of PBC patients with anti-Sp100 than in those without anti-Sp100 (67% vs 29%, p = 0.0710).

CONCLUSION

anti-Sp100 does not become a complementary serological marker for PBC in AMA-negative patients. A bacterial infection may trigger the production of anti-Sp100. Another factor is required to initiate the autoantibody production.

Fibrotic Events in the Progression of Cholestatic Liver Disease

Cholestatic liver diseases including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are associated with active hepatic fibrogenesis, which can ultimately lead to the development of cirrhosis. However, the exact relationship between the development of liver fibrosis and the progression of cholestatic liver disease remains elusive. Periductular fibroblasts located around the bile ducts seem biologically different from hepatic stellate cells (HSCs). The fibrotic events in these clinical conditions appear to be related to complex crosstalk between immune/inflammatory mechanisms, cytokine signalling, and perturbed homeostasis between cholangiocytes and mesenchymal cells. Several animal models including bile duct ligation (BDL) and the Mdr2-knockout mice have improved our understanding of mechanisms underlying chronic cholestasis. In the present review, we aim to elucidate the mechanisms of fibrosis in order to help to identify potential diagnostic and therapeutic targets.

The Glycolytic Pathway as a Target for Novel Onco-Immunology Therapies in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal forms of human cancer, characterized by unrestrained progression, invasiveness and treatment resistance. To date, there are limited curative options, with surgical resection as the only effective strategy, hence the urgent need to discover novel therapies. A platform of onco-immunology targets is represented by molecules that play a role in the reprogrammed cellular metabolism as one hallmark of cancer. Due to the hypoxic tumor microenvironment (TME), PDA cells display an altered glucose metabolism-resulting in its increased uptake-and a higher glycolytic rate, which leads to lactate accumulation and them acting as fuel for cancer cells. The consequent acidification of the TME results in immunosuppression, which impairs the antitumor immunity. This review analyzes the genetic background and the emerging glycolytic enzymes that are involved in tumor progression, development and metastasis, and how this represents feasible therapeutic targets to counteract PDA. In particular, as the overexpressed or mutated glycolytic enzymes stimulate both humoral and cellular immune responses, we will discuss their possible exploitation as immunological targets in anti-PDA therapeutic strategies.

Role of Antinuclear Antibodies in Primary Biliary Cholangitis

The identification of antinuclear antibodies specific for primary biliary cholangitis (PBC) has facilitated diagnosis in antimitochondrial antibody-negative individuals. Their presence may also have prognostic implication. In this edition of The American Journal of Gastroenterology, Reig et al. evaluate the frequency of PBC-specific antinuclear antibodies, their natural course and association with outcomes in 254 patients with PBC. Antibodies remained stable over time, and presence of antihexokinase1 and anti-sp100 was associated with shorter survival. Clinicians can request testing for PBC-specific antinuclear antibodies to minimize need for liver biopsy, but further research is needed to understand their role in disease prognostication.