Genetic risk factors for autoimmune hepatitis: implications for phenotypic heterogeneity and biomarkers for drug response

Characteristics of peripheral blood mononuclear cells and potential related molecular mechanisms in patients with autoimmune hepatitis: a single-cell RNA sequencing analysis

Autoimmune hepatitis (AIH) is an immune disorder characterized by hypergammaglobulinemia, autoantibodies, and chronic active hepatitis on liver histology. However, immune cell population characteristics in AIH patients remain poorly understood. This study was designed to analyze peripheral blood mononuclear cell (PBMC) characteristics in AIH through single-cell RNA sequencing (scRNA-seq) and explore potential AIH-related molecular mechanisms. We generated 3690 and 3511 single-cell transcriptomes of PBMCs pooled from 4 healthy controls (HCs) and 4 AIH patients, respectively, by scRNA-seq. These pooled PBMC transcriptomes were used for cell cluster identification and differentially expressed gene (DEG) identification. GO functional enrichment analysis was performed on the DEGs to determine the most active AIH immune cell biological functions. Although the PCA-based uniform manifold approximation and projection (UMAP) algorithm was used to cluster cells with similar expression patterns in the two samples, 87 up- and 12 downregulated DEGs were retained in monocytes and 101 up- and 15 downregulated DEGs were retained in NK cells from AIH PBMCs. Moreover, enriched GO terms in the PBMC-derived monocyte and NK cell clusters were related mainly to antigen processing and presentation, IFN-γ-mediated signaling, and neutrophil degranulation and activation. These potential molecular mechanisms may be important targets for AIH treatment.

Autoimmune hepatitis: Brighton Collaboration case definition and guidelines for data collection, analysis, and presentation of immunisation safety data

This report introduces a Brighton Collaboration (BC) case definition for autoimmune hepatitis (AIH), which has been classified as a priority adverse event of special interest (AESI), as there were possible cases seen following COVID-19 vaccination. The case definition was developed by a group of subject matter and BC process experts to facilitate safety data comparability across pre- and post-licensure clinical trials, as well as pharmacovigilance activities in multiple settings with diverse resources and healthcare access. The usual BC case definition development process was followed in an expedited manner, and took two months to complete, including finalising the manuscript for publication, instead of the usual 1 year development time. It includes a systematic review of the literature and an expert consensus to define levels of diagnostic certainty for AIH, and provides specific guidelines for data collection and analysis. Histology, serological and biochemical tests and exclusion of alternate diagnosis were considered necessary to define the levels of certainty (definitive, probable and possible). AEFI reports of suspected AIH were independently classified by the WG members to test its useability and these classifications were used to finalise the case definition. The document underwent peer review by external AIH experts and a Reference Group of vaccine safety stakeholders in high-, low- and middle-income countries to ensure case definition useability, applicability, and scientific integrity. The expedited process can be replicated for development of other standardised case definitions for priority AESIs for endemics and epidemics. While applicable to cases reported following immunisation, the case definition is independent of lapsed time following vaccination and, as such, can also be used to determine background incidence for vaccinated and unvaccinated control groups in studies of causal association. While use of this case definition is also appropriate for the study of safety of other products including drugs, it is not meant to guide clinical case management.

HLA inherence as a potential parameter in checkpoint inhibitor-associated autoimmune adverse event assessment

Background

The success of immunotherapy has made it a lifesaving treatment, but not without side effects. Currently, the risk factors for developing immune-related adverse events (irAEs) in patients who receive immunotherapy are poorly understood, and there is no risk-stratifying mechanism for potentially fatal irAEs. It is postulated that oncology patients with preexisting autoimmune diseases are likely to have flares on immunotherapy. However, some patients develop de novo autoimmune conditions on immunotherapy without a prior history. Literature reports have postulated that human leukocyte antigen (HLA) inherence may play a role in irAEs. However, this potential remains underexplored.

Methods

The oncology patients who developed autoimmune adverse events on immunotherapy for whom the continuation of treatment was prudent or lifesaving were selected. Of note, all nine patients received checkpoint inhibitors (CIs). Of the nine selected patients, only one had a prior history of an autoimmune condition. None of the nine selected patients had an active autoimmune condition at the time of CI initiation. Their HLA was typed, and the results were cross-referenced with the literature reports in PubMed and Google search with the corresponding autoimmune condition of each patient.

Results

Herein, we report nine patients with irAEs for whom retrospective HLA typing revealed the inherence of multiple related HLA alleles that may correspond to the autoimmune condition that they had developed on immunotherapy. It is to be mentioned that the inherence of enriched disease-related HLA alleles was shared among patients with the same irAEs. These patients developed a range of irAEs including bullous pemphigoid, pemphigus foliaceus/vulgaris, thyroiditis, vitiligo, and hepatitis on immunotherapy. Although some combinations of disease-related HLA were well reported in otherwise idiopathic autoimmune diseases, a frequently repeated HLA allele combination in our patient population was found to be rarely seen in the general population.

Conclusion

The authors suggest that an enriched inherence of disease-related HLA alleles may play a role in the genetic propensity for the development of irAEs in oncology patients, who receive immunotherapy, including CIs. Inherence of more than one or a cluster of particular autoimmune disease-related HLA alleles in patients who receive immunotherapy may unmask the corresponding autoimmune disease as the genotype inherence presents with the phenotype of the corresponding condition. It is suggested that enriched linked HLA genotypes, which are otherwise rare in the general population, may present as the corresponding phenotype of the autoimmune condition. Such clinical presentation, enhanced by immunotherapy, such as CIs, can play a role in risk stratifying patients for precision medicine and improve the outcome.

A nomogram for analyzing risk factors of poor treatment response in patients with autoimmune hepatitis

OBJECTIVE

The objective of this study was to identify biochemical and clinical predictors of poor response (including incomplete response and non-response) to standard treatment in autoimmune hepatitis (AIH) patients.

METHODS

This study retrospectively collected clinical data from 297 patients who were first diagnosed with AIH in Beijing Ditan Hospital from 2010 to 2019. Finally, 149 patients were screened out. Risk factors were screened by univariate and multifactorial logistic regression. Then they were used to establish the nomogram. The ROC curve, calibration curve, decision curves analysis (DCA) and clinical impact curves (CIC) were used to evaluate the nomogram.

RESULTS

149 patients were divided into two groups: the response group (n = 120, 80%) and the poor response group (n = 29, 20%). Multivariate logistic regression analysis found that IgG > 26.5 g/L (OR: 22.016; 95% CI: 4.677-103.640) in AIH patients increased the risk. In contrast, treatment response status was better in women (OR: 0.085; 95% CI: 0.015-0.497) aged >60 years (OR: 0.159; 95% CI: 0.045-0.564) with AST > 4.49 × ULN (OR: 0.066; 95% CI: 0.009-0.494). The C index (0.853) and the calibration curve show that the nomogram is well differentiated and calibrated; the DCA and CIC indicate that the model has good clinical benefits and implications.

CONCLUSION

The study found that male patients aged ≤ 60 years with IgG > 26.5 g/L and elevated AST ≤ 4.49 × ULN were more likely to have a non-response/incomplete response to standard treatment.

The pleiotropic approach to coronavirus disease-19 pathogenesis: The impact of liver diseases associated host genetic variants

Coronavirus disease-2019 (COVID-19) is a novel multisystemic viral disease caused pandemic. The disease impact involves liver and associated systems. Undoubtedly, host genetic background influences the predisposition and prediction of infection. Variants among human populations might increase susceptibility or protect against severe outcomes. In this manner, rs738409 variant of patatin-like phospholipase domain-containing protein 3 gene appears to be protective in some populations in spite of its aggravating effect on non-alcoholic fatty liver diseases (NAFLDs) and steatohepatitis. DRB1*15:01 allele of human leukocyte antigen is associated with protective effect in European and Japanese populations. DRB1*03:01 contrarily increases the susceptibility of severe COVID-19 infection in European populations. rs1260326 in glucokinase regulatory protein gene, rs112875651 in tribbles homolog 1 gene, rs429358 in apolipoprotein 1, and rs58542926 in transmembrane 6 superfamily 2 alleles are found related with NAFLD and obesity; thus, hypercoagulability and severe COVID-19 outcomes. In chronic or acute liver diseases, comorbid syndromes are the key factors to explain increased severity. There might not be a direct association between the variant and severe COVID-19 infection. As it is concluded, there are genes and variants known and unknown yet to be studied to reveal the association with disease severity.

Autoimmune liver diseases and diabetes: A propensity score matched analysis and a proportional meta-analysis

BACKGROUND AND AIMS

Patients with some chronic liver diseases have increased risk of diabetes. Whether this is also the case for patients with autoimmune liver diseases is unknown. The study aimed to calculate risk and worldwide prevalence of diabetes in patients with autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC).

METHODS

We performed a case-control study using data from the United Kingdom Biobank (UKB) and compared frequency of type 1 diabetes (T1D) and type 2 diabetes (T2D) in AIH and PBC with age-, sex-, BMI- and ethnicity-matched controls. Next, we performed a systematic review and proportional meta-analysis searching PubMed, Embase, Cochrane Library and Web of Science (inception to 1 May 2022 [AIH]; 20 August 2022 [PBC]; 11 November 2022 [PSC]). The pooled prevalence of diabetes was calculated using an inverse method random effects model.

RESULTS

Three hundred twenty-eight AIH patients and 345 PBC patients were identified in UKB and risk of T1D and T2D significantly increased compared with matched controls. Our systematic search identified 6914 records including the UKB study. Of these, 77 studies were eligible for inclusion comprising 36 467, 39 924 and 4877 individuals with AIH, PBC and PSC, respectively. The pooled prevalence of T1D was 3.8% (2.6%-5.7%), 1.7% (0.9%-3.1%), 3.1% (1.9%-4.8%) and of T2D 14.8% (11.1%-19.5%), 18.1% (14.6%-22.2%), 6.3% (2.8%-13.3%) in patients with AIH, PBC and PSC, respectively.

CONCLUSIONS

Patients with autoimmune liver diseases have increased risk of diabetes. Increased awareness of diabetes risk in patients with autoimmune liver diseases is warranted.

Profiling of mouse and human liver diseases identifies targets for therapeutic treatment of autoimmune hepatitis

Autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and non-alcoholic steatohepatitis (NASH) are chronic liver diseases (CLDs) of distinct etiologies that represent a public health risk with limited therapeutic options. A common feature among CLDs is an aggressive T cell response resulting in destruction of liver tissue and fibrosis. Here, we assessed the presence and nature of T cell inflammation in late-stage human AIH, PSC and NASH and examined whether targeting the T cell response can improve disease pathology in a mouse model (Traf6ΔTEC) of spontaneous AIH. T cell infiltration and ensuing inflammatory pathways were present in human AIH and PSC and to a lesser extent in NASH. However, we observed qualitative differences in infiltrating T cell subsets and upregulation of inflammatory pathways among these diseases, while mouse and human AIH exhibited similar immunogenic signatures. While gene expression profiles differed among diseases, we identified 52 genes commonly upregulated across all diseases that included the JAK3 tyrosine kinase. Therapeutic targeting of chronic AIH with the JAK inhibitor tofacitinib reduced hepatic T cell infiltration, AIH histopathology and associated immune parameters in treated Traf6ΔTEC mice. Our results indicate that targeting T cell responses in established hepatic autoimmune inflammation is a feasible strategy for developing novel therapeutic approaches to treat AIH and possibly other CLDs irrespective of etiology.

Autoimmune liver diseases and diabetes

Autoimmune liver diseases include autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis. They are chronic, heterogenous diseases affecting the liver which is a key metabolic organ that ensures glucose homeostasis. It is well known that patients with other chronic liver diseases such as cirrhosis and nonalcoholic fatty liver disease (NAFLD) display glucose disturbances like insulin resistance and have an increased risk of diabetes. Previous evidence on glucose disturbances in patients with autoimmune liver disease is scarce but does point towards a potentially increased risk of type 1 diabetes and type 2 diabetes. The underlying mechanisms are unknown but may reflect genetic predisposition, concurrent NAFLD and or cirrhosis development, and treatment (steroid) related impairment of glucose homeostasis. Therefore, increased awareness and surveillance of diabetes development in patients with autoimmune liver disease may be important. Overall, detection and treatment of diabetes generally follow the usual diabetes guidelines; however, in patients with advanced liver cirrhosis, HbA1c may not be a reliable marker of average glucose levels, and treatment with insulin is generally recommended. In addition, it has recently been suggested that sodium-glucose cotransporter 2 inhibitors may be beneficial in treating refractory ascites. Further research on diabetes risk in autoimmune liver disease is warranted.

Associations between HLA class II alleles and IgE sensitization to allergens in the Qatar Biobank cohort

Background

Allergic disorders are the consequence of IgE sensitization to allergens. Population studies have shown that certain human leukocyte antigen (HLA) alleles are associated with increased or decreased risk of developing allergy.

Objective

We aimed to characterize the relationship between HLA class II allelic diversity and IgE sensitization in an understudied Arab population.

Methods

We explored associations between IgE sensitization to 7 allergen mixes and mesquite (comprising 41 food or aeroallergens) and 45 common classical HLA class II alleles in a well-defined cohort of 797 individuals representing the general adult population of Qatari nationals and long-term residents. To do so, we performed HLA calling from whole genome sequencing data at 2-field resolution using 2 independent algorithms. We then applied 3 different regression models to assess either each allergen mix independently, in the context of IgE sensitization to other allergens tested, or polysensitization.

Results

More than half (n = 447) of the study participants showed IgE sensitization to at least 1 allergen, most of them (n = 400) to aeroallergens (Phadiatop). We identified statistically significant negative and positive associations with 24 HLA class II alleles. These have been reported to confer risk or protection from variety of diseases; however, only a few have previously been associated with allergy in other populations.

Conclusions

Our study reveals several new risk and protective genetic markers for allergen-specific IgE sensitization. This is a first and essential step toward a better understanding of the origins of allergic diseases in this understudied population.

The Threat of Weight-Loss Over the Counter Supplements: A Case of Camellia Sinensis Autoimmune Hepatitis

Autoimmune hepatitis (AIH) arises as a result of environmental and immunological interactions. Herbal and dietary supplements (HDS) are known triggers, and approximately half of the U.S. adult population consumes them, even though they are restricted. Therefore, the importance of recognizing potential triggers of AIH is considered relevant. The mechanism behind HDS Camellia Sinensis inducing AIH is related to its compounds, catechins, which induce reactive oxygen species leading to a liver immune-mediated response. We present here a challenging case of a middle-aged woman with AIH following the consumption of a weight-loss Mexican green tea containing Camellia Sinensis.

HLA and Non-HLA gene polymorphisms in autoimmune hepatitis patients of North Indian adults

Autoimmune hepatitis (AIH) is a chronic and progressive disease of the liver. This is a multifactorial autoimmune disease with both environmental factors and genetic factors playing a role in its pathogenesis. Certain environmental agents like viruses, drugs, etc., can trigger the disease in a genetically susceptible individual. The present study was aimed to explore the distribution of human leukocyte antigen (HLA)-DRB1, Protein tyrosine phosphatase non-receptor type 22 (PTPN22) and Cytotoxic T-Lymphocyte-associated protein 4 (CTLA-4) polymorphisms in North Indian adult AIH patients and their associations with clinical and pathological characteristics associated with the disease. A total of 147 subjects with 47 cases and 100 healthy controls were enrolled. Diagnosis of AIH was made by Revised International Autoimmune Hepatitis Group scoring system. HLA-DRB1 Typing was done by Luminex-based reverse Sequence-Specific Oligonucleotide Probing (SSOP). Single nucleotide variant (SNV) genotyping for CTLA-4 and PTPN22 was done by simple probe-based SNP arrays. Results indicated SLA positive AIH patients are poor responders to therapy. A significant predispositional association of HLA-DRB1*03 was observed in AIH patients from the North Indian population (p= 0.0001, OR=4.83 (2.30-10.15). The frequency of the GG genotype of CTLA-4 CT 60 was significantly increased in AIH patients compared to controls. Multinomial analysis showed that CTLA-4 CT 60 is an independent predictor for cases.

Therapeutic Perspectives of IL1 Family Members in Liver Diseases: An Update

Interleukin (IL) 1 superfamily members are a cornerstone of a variety of inflammatory processes occurring in various organs including the liver. Progression of acute and chronic liver diseases regardless of etiology depends on the stage of hepatocyte damage, the release of inflammatory cytokines and disturbances in gut microbiota. IL1 cytokines and receptors can have pro- or anti-inflammatory roles, even dual functionalities conditioned by the microenvironment. Developing novel therapeutic strategies to block the IL1/IL1R signaling pathways seems like a reasonable option. This mode of action is now exploited by anakinra and canakinumab, which are used to treat different inflammatory illnesses, and studies in liver diseases are on the way. In this mini review, we have focused on the IL1 superfamily members, given their crucial role in liver inflammation diseases, specifically discussing their potential role in developing new treatment strategies.

Epidemiology and surveillance of autoimmune hepatitis in Asia

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease that mainly injures the hepatocytes. The autoimmune disease might be involved in its aetiology, but this remains to be confirmed. Recently epidemiological studies of AIH in Asia have been broadly conducted, revealing characteristics and management of AIH patients in Asia. In East Asia, most AIH patients are type 1, and type 2 AIH is very rare. However, type 2 AIH in South Asia is as frequent as in Europe and the USA. HLA-DR4 is associated with the characteristics of type 1 AIH in East Asia, whereas HLA-DR3 occurs in AIH patients from South Asia. AIH prevalence worldwide is increasing, and several studies have reported a prevalence of 19.44, 22.80 and 12.99 per 100 000 people in Europe, the USA and Asia respectively. A meta-analysis of studies on AIH showed similar annual incidence rates for all regions, with 1.31, 1.37 and 1.00 per 100 000 people in Asia, Europe and the USA respectively. The increase in the rates could be attributable to the increased awareness of disease concepts and diagnosis. In South Asia, most cases were diagnosed as AIH only after having progressed to cirrhosis, which may cause a higher mortality rate in South Asia than in East Asia. Therefore, the early diagnosis and treatment of AIH patients can improve the current situation in Asia.

Overview of autoimmune liver disease: Prevalence, risk factors, and role of autoantibodies

Content available: Author Interview and Audio Recording.

Pathogenesis of Autoimmune Hepatitis-Cellular and Molecular Mechanisms

Pediatric autoimmune liver disorders include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is an idiopathic disease characterized by immune-mediated hepatocyte injury associated with the destruction of liver cells, causing inflammation, liver failure, and fibrosis, typically associated with autoantibodies. The etiology of AIH is not entirely unraveled, but evidence supports an intricate interaction among genetic variants, environmental factors, and epigenetic modifications. The pathogenesis of AIH comprises the interaction between specific genetic traits and molecular mimicry for disease development, impaired immunoregulatory mechanisms, including CD4+ T cell population and Treg cells, alongside other contributory roles played by CD8+ cytotoxicity and autoantibody production by B cells. These findings delineate an intricate pathway that includes gene to gene and gene to environment interactions with various drugs, viral infections, and the complex microbiome. Epigenetics emphasizes gene expression through hereditary and reversible modifications of the chromatin architecture without interfering with the DNA sequence. These alterations comprise DNA methylation, histone transformations, and non-coding small (miRNA) and long (lncRNA) RNA transcriptions. The current first-line therapy comprises prednisolone plus azathioprine to induce clinical and biochemical remission. Further understanding of the cellular and molecular mechanisms encountered in AIH may depict their impact on clinical aspects, detect biomarkers, and guide toward novel, effective, and better-targeted therapies with fewer side effects.

Environmental exposure as a risk-modifying factor in liver diseases: Knowns and unknowns

Liver diseases are considered to predominantly possess an inherited or xenobiotic etiology. However, inheritance drives the ability to appropriately adapt to environmental stressors, and disease is the culmination of a maladaptive response. Thus “pure” genetic and “pure” xenobiotic liver diseases are modified by each other and other factors, identified or unknown. The purpose of this review is to highlight the knowledgebase of environmental exposure as a potential risk modifying agent for the development of liver disease by other causes. This exercise is not to argue that all liver diseases have an environmental component, but to challenge the assumption that the current state of our knowledge is sufficient in all cases to conclusively dismiss this as a possibility. This review also discusses key new tools and approaches that will likely be critical to address this question in the future. Taken together, identifying the key gaps in our understanding is critical for the field to move forward, or at the very least to “know what we don't know.”

Impact of genetic and environmental factors on autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic non-resolving liver disease characterized by diffuse hypergammaglobulinemia, the presence of autoantibodies and characteristic histological findings. The disease can have catastrophic outcome with the development of end-stage liver disease if misdiagnosed/undiagnosed and left untreated. AIH pathogenesis remains obscure and the main hypothesis supports its development in genetically predisposed individuals after being exposed to certain environmental triggers. Genetic predisposition is linked to the presence of certain HLA alleles, mainly HLA-DR3 and HLA-DR4. However, a wide number of non-HLA epitopes have also been associated with the disease although data vary significantly among different ethnic groups. Therefore, it is likely that epigenetic alterations may also play a crucial role in disease's pathogenesis, although not yet extensively studied. The aim of this review was to summarize the genetic and environmental factors that have been associated with AIH, but also to open new insights towards the role of epigenetic modifications in the etiology of the disease.

Pathogenesis of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic progressive liver disease whose etiology and pathogenesis are not yet clear. It is currently believed that the occurrence of AIH is closely related to genetic susceptibility and immune abnormalities, and other factors such as environment, viral infection and drugs that may cause immune dysfunction. This article reviews the pathogenesis of AIH and describes the latest research results in the past 5 years.