MiR-326 sponges TET2 triggering imbalance of Th17/Treg differentiation to exacerbate pyroptosis of hepatocytes in concanavalin A-induced autoimmune hepatitis

INTRODUCTION AND OBJECTIVES

MicroRNA-326 is abnormally expressed in autoimmune diseases, but its roles in autoimmune hepatitis (AIH) are unknown. In this study, we aimed to investigate the effect of miR-326 on AIH and the underlying mechanism.

MATERIALS AND METHODS

Concanavalin A was administrated to induce AIH in mice and the expression levels of miR-326 and TET2 was evaluated by qRT-PCR and western blot, respectively. The percentages of Th17 and Treg cells were evaluated by flow cytometry and their marker proteins were determined by western blot and ELISA. The mitochondrial membrane potential (MMP) and ROS level were tested with the JC-1 kit and DCFH-DA assay. The binding relationships between miR-326 and TET2 were verified by dual-luciferase reporter assay. The liver tissues were stained by the HE staining. In vitro, AML12 cells were cocultured with mouse CD4+T cells. The expression levels of pyroptosis-related proteins were assessed by western blot.

RESULTS

Concanavalin A triggered AIH and enhanced the expression level of miR-326 in mice. It increased both Th17/Treg ratio and the levels of their marker proteins. The expression of TET2 was decreased in AIH mice. Knockdown of miR-326 could decrease the levels of pyroptosis-related proteins, the ROS level and increase MMP. In mouse CD4+T cells, miR-326 sponged TET2 to release IL-17A. Coculture of AML12 cells with isolated CD4+T cells from miR-326 knockdown AIH mice could relieve pyroptosis.

CONCLUSIONS

Knockdown of miR-326 exerted anti-pyroptosis effects via suppressing TET2 and downstream NF-κB signaling to dampen AIH. We highlighted a therapeutic target in AIH.

Multi-omics approaches for drug-response characterization in primary biliary cholangitis and autoimmune hepatitis variant syndrome

BACKGROUND

Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) variant syndrome (VS) exhibit a complex overlap of AIH features with PBC, leading to poorer prognoses than those with PBC or AIH alone. The biomarkers associated with drug response and potential molecular mechanisms in this syndrome have not been fully elucidated.

METHODS

Whole-transcriptome sequencing was employed to discern differentially expressed (DE) RNAs within good responders (GR) and poor responders (PR) among patients with PBC/AIH VS. Subsequent gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted for the identified DE RNAs. Plasma metabolomics was employed to delineate the metabolic profiles distinguishing PR and GR groups. The quantification of immune cell profiles and associated cytokines was achieved through flow cytometry and immunoassay technology. Uni- and multivariable logistic regression analyses were conducted to construct a predictive model for insufficient biochemical response. The performance of the model was assessed by computing the area under the receiver operating characteristic (AUC) curve, sensitivity, and specificity.

FINDINGS

The analysis identified 224 differentially expressed (DE) mRNAs, 189 DE long non-coding RNAs, 39 DE circular RNAs, and 63 DE microRNAs. Functional pathway analysis revealed enrichment in lipid metabolic pathways and immune response. Metabolomics disclosed dysregulated lipid metabolism and identified PC (18:2/18:2) and PC (16:0/20:3) as predictors. CD4+ T helper (Th) cells, including Th2 cells and regulatory T cells (Tregs), were upregulated in the GR group. Pro-inflammatory cytokines (IFN-γ, TNF-α, IL-9, and IL-17) were downregulated in the GR group, while anti-inflammatory cytokines (IL-10, IL-4, IL-5, and IL-22) were elevated. Regulatory networks were constructed, identifying CACNA1H and ACAA1 as target genes. A predictive model based on these indicators demonstrated an AUC of 0.986 in the primary cohort and an AUC of 0.940 in the validation cohort for predicting complete biochemical response.

CONCLUSION

A combined model integrating genomic, metabolic, and cytokinomic features demonstrated high accuracy in predicting insufficient biochemical response in patients with PBC/AIH VS. Early recognition of individuals at elevated risk for insufficient response allows for the prompt initiation of additional treatments.

Silencing of aryl hydrocarbon receptor repressor restrains Th17 cell immunity in autoimmune hepatitis

Th17-cells play a key role in the pathogenesis of autoimmune hepatitis (AIH). Dysregulation of Th17-cells in AIH is linked to defective response to aryl-hydrocarbon-receptor (AhR) activation. AhR modulates adaptive immunity and is regulated by aryl-hydrocarbon-receptor-repressor (AHRR), which inhibits AhR transcriptional activity. In this study, we investigated whether defective Th17-cell response to AhR derives from aberrant AHRR regulation in AIH. Th17-cells, obtained from the peripheral blood of AIH patients (n = 30) and healthy controls (n = 30) were exposed to AhR endogenous ligands, and their response assessed in the absence or presence of AHRR silencing. Therapeutic effects of AHRR blockade were tested in a model of Concanavalin-A (Con-A)-induced liver injury in humanized mice. AHRR was markedly upregulated in AIH Th17-cells, following exposure to l-kynurenine, an AhR endogenous ligand. In patients, silencing of AHRR boosted Th17-cell response to l-kynurenine, as reflected by increased levels of CYP1A1, the main gene controlled by AhR; and decreased IL17A expression. Blockade of AHRR limited the differentiation of naïve CD4-cells into Th17 lymphocytes; and modulated Th17-cell metabolic profile by increasing the levels of uridine via ATP depletion or pyrimidine salvage. Treatment with 2'-deoxy-2'-fluoro-d-arabinonucleic acid (FANA) oligonucleotides to silence human AHRR in vivo, reduced ALT levels, attenuated lymphocyte infiltration on histology, and heightened frequencies of regulatory immune subsets in NOD/scid/gamma mice, reconstituted with human CD4 cells, and exposed to Con-A. In conclusion, blockade of AHRR in AIH restores Th17-cell response to AHR, and limits Th17-cell differentiation through generation of uridine. In vivo, silencing of AHRR attenuates liver damage in NOD/scid/gamma mice. Blockade of AHRR might therefore represent a novel therapeutic strategy to modulate effector Th17-cell immunity and restore homeostasis in AIH.

Protein-centric omics analysis reveals circulating complements linked to non-viral liver diseases as potential therapeutic targets

BACKGROUND/AIMS

To evaluate the causal correlation between complement components and non-viral liver diseases and their potential use as druggable targets.

METHODS

We conducted Mendelian randomization (MR) to assess the causal role of circulating complements in the risk of non-viral liver diseases. A complement-centric protein interaction network was constructed to explore biological functions and identify potential therapeutic options.

RESULTS

In the MR analysis, genetically predicted levels of complement C1q C chain (C1QC) were positively associated with the risk of autoimmune hepatitis (odds ratio 1.125, 95% confidence interval 1.018-1.244), while complement factor H-related protein 5 (CFHR5) was positively associated with the risk of primary sclerosing cholangitis (PSC;1.193, 1.048- 1.357). On the other hand, CFHR1 (0.621, 0.497-0.776) and CFHR2 (0.824, 0.703-0.965) were inversely associated with the risk of alcohol-related cirrhosis. There were also significant inverse associations between C8 gamma chain (C8G) and PSC (0.832, 0.707-0.979), as well as the risk of metabolic dysfunction-associated steatotic liver disease (1.167, 1.036-1.314). Additionally, C1S (0.111, 0.018-0.672), C7 (1.631, 1.190-2.236), and CFHR2 (1.279, 1.059-1.546) were significantly associated with the risk of hepatocellular carcinoma. Proteins from the complement regulatory networks and various liver diseaserelated proteins share common biological processes. Furthermore, potential therapeutic drugs for various liver diseases were identified through drug repurposing based on the complement regulatory network.

CONCLUSION

Our study suggests that certain complement components, including C1S, C1QC, CFHR1, CFHR2, CFHR5, C7, and C8G, might play a role in non-viral liver diseases and could be potential targets for drug development.

PD-L1 expression levels in mesenchymal stromal cells predict their therapeutic values for autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis is a chronic inflammatory hepatic disorder with no effective treatment. Mesenchymal stromal cells (MSCs) have emerged as a promising treatment owing to their unique advantages. However, their heterogeneity is hampering use in clinical applications.

METHODS

Wharton's jelly derived MSCs (WJ-MSCs) were isolated from 58 human donors using current good manufacturing practice conditions. Gene expression profiles of the WJ-MSCs were analyzed by transcriptome and single-cell RNA-sequencing (scRNA-seq), and subsequent functional differences were assessed. Expression levels of programmed death-ligand 1 (PD-L1) were used as an indicator to screen WJ-MSCs with varied immunomodulation activities and assessed their corresponding therapeutic effects in a mouse model of concanavalin A-induced autoimmune hepatitis.

RESULTS

The 58 different donor-derived WJ-MSCs were grouped into six gene expression profile clusters. The gene in different clusters displayed obvious variations in cell proliferation, differentiation bias, trophic factor secretion, and immunoregulation. Data of scRNA-seq revealed four distinct WJ-MSCs subpopulations. Notably, the different immunosuppression capacities of WJ-MSCs were positively correlated with PD-L1 expression. WJ-MSCs with high expression of PD-L1 were therapeutically superior to WJ-MSCs with low PD-L1 expression in treating autoimmune hepatitis.

CONCLUSION

PD-L1 expression levels of WJ-MSCs could be regarded as an indicator to choose optimal MSCs for treating autoimmune disease. These findings provided novel insights into the quality control of MSCs and will inform improvements in the therapeutic benefits of MSCs.

sFgl2 gene-modified MSCs regulate the differentiation of CD4+ T cells in the treatment of autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is a T-cell-mediated autoimmune liver disease that can lead to liver injury and has a poor long-term prognosis. Mesenchymal stromal cells (MSCs) have immunosuppressive effects and can treat AIH. CD4+ T cells express the unique inhibitory Fcγ receptor (FcγRIIB), which is the only receptor for the immunosuppressive factor soluble fibrinogen-like protein 2 (sFgl2). This study aimed to examine the therapeutic effect of sFgl2 gene-modified MSCs (sFgl2-MSCs) on AIH.

METHODS

MSCs were obtained from the inguinal fat of mice and cocultured with CD4+ T cells sorted from mouse spleens. FcγRIIB expression on CD4+ T cells was determined by flow cytometry. sFgl2 expression in MSCs transfected with lentiviral vectors carrying the Fgl2 gene and a green fluorescent protein-encoding sequence was determined by enzyme-linked immunosorbent assay. The percentages of Th1 cells Th17 cells and regulatory T cells (Tregs) were determined by flow cytometry And the levels of p-SHP2 and p-SMAD2/3 were detected by Western blotting after the cells were cocultured with MSCs for 72 h. After locating MSCs by in vivo imaging Con A-induced experimental AIH mice were randomly divided into 4 groups and administered different treatments. After 24 h histopathological scores liver function and cytokine levels were examined and the proportions of CD4+ T cells CD8+ T cells Tregs Th17 cells and Th1 cells in the spleen and liver were determined by flow cytometry. In addition immunohistochemical staining was used to detect the liver infiltration of T-bet-, Foxp3- and RORγ-positive cells.

RESULTS

FcγRIIB expression on CD4+ T cells was upregulated after coculture with MSCs. After coculture with sFgl2-MSCs, the proportion of Tregs among CD4+ T cells increased, the proportion of Th17 and Th1 cells decreased, and the levels of p-SHP2 and p-SMAD2/3 increased. In vivo, sFgl2-MSCs significantly improved liver function, decreased liver necrosis area, decreased tumor necrosis factor-α, interleukin (IL)-1β and IL-6 expression, increased IL-10 expression, reduced liver infiltration of CD4+ T and CD8+ T cells, increased the proportion of Tregs and reduced the proportions of Th17 and Th1 cells in mice.

CONCLUSION

By promoting Tregs differentiation and inhibiting Th17 and Th1 cell differentiation, sFgl2 gene-modified MSCs have a more powerful therapeutic effect on Con A-induced experimental AIH and may represent a strategy for the clinical treatment of AIH.

Causal effects of gut microbiome on autoimmune liver disease: a two-sample Mendelian randomization study

BACKGROUND

Epidemiological studies have indicated a potential link between the gut microbiome and autoimmune liver disease (AILD) such as autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC). The relationship between the gut microbiome and autoimmune liver disease is still uncertain due to confounding variables. In our study, we aim to shed light on this relationship by employing a two-sample Mendelian randomization approach.

METHODS

We conducted a two-sample Mendelian randomization (MR) study using the R package "TwoSampleMR". The exposure data consisted of genetic variants associated with 194 bacterial traits obtained from the MiBioGen consortium. Summary statistics for AILD were obtained from the GWAS Catalog website. Furthermore, a series of sensitivity analyses were performed to validate the initial MR results.

RESULTS

There were two, four and three bacteria traits associated with an increased risk of AIH. PBC, and PSC respectively. In contrast, there were five, two and five bacteria traits associated with a decreased risk for AIH, PBC and PSC. Notably, the genus_Clostridium_innocuum_group showed a negative association with AIH (OR = 0.67, 95% CI: 0.49-0.93), and the genus_Actinomyces was found to be genetically associated with a decreased risk of PSC (OR = 0.62, 95% CI: 0.42-0.90).

CONCLUSIONS

Our study identified the causal impact of specific bacterial features on the risk of AILD subtypes. Particularly, the genus_Clostridium_innocuum_group and the genus_Actinomyces demonstrated significant protective effects against AIH and PSC respectively. These findings provide further support for the potential use of targeted probiotics in the management of AILD.

Novel HLA allele associations with susceptibility, staging, symptomatic state, autoimmune hepatitis and hepatocellular carcinoma events for primary biliary cholangitis in the Japanese population

Primary biliary cholangitis (PBC) is a rare autoimmune disease with a clear predisposition for human leukocyte antigen (HLA)-DR/DQ-associated loss of immune tolerance for the E2 component of the pyruvate dehydrogenase complex. Three-field-resolution HLA imputation of 1,670 Japanese PBC patients and 2,328 healthy controls was conducted using Japanese population-specific HLA reference panels. Eighteen previously reported Japanese PBC-associated HLA alleles were confirmed and extended to 3-field-resolution, including HLA-DRB1*08:03 to HLA-DRB1*08:03:02, HLA-DQB1*03:01 to HLA-DQB1*03:01:01, HLA-DQB1*04:01 to HLA-DQB1*04:01:01 and HLA-DQB1*06:04 to HLA-DQB1*06:04:01. In addition, additional significant novel HLA alleles were identified, including 3 novel susceptible HLA-DQA1 alleles: HLA-DQA1*03:03:01, HLA-DQA1*04:01:01, HLA-DQA1*01:04:01 and 1 novel protective HLA-DQA1 allele, HLA-DQA1*05:05:01. In addition, PBC patients carrying HLA-DRB1*15:01:01 and HLA-DQA1*03:03:01 would have a higher predisposition toward developing concomitant autoimmune hepatitis (AIH). Further, late-stage and symptomatic PBC shared the same susceptible HLA alleles of HLA-A*26:01:01, HLA-DRB1*09:01:02 and HLA-DQB1*03:03:02. Lastly, HLA-DPB1*05:01:01 was identified as a potential risk HLA allele for development of hepatocellular carcinoma (HCC) in PBC patients. In conclusion, we have extended the current knowledge of HLA allele associations to 3-field resolution and identified novel HLA allele associations with predisposition risk, staging, symptomatic state, and AIH and HCC events for Japanese PBC patients.

Hepatocyte estrogen sulfotransferase inhibition protects female mice from concanavalin A-induced T cell-mediated hepatitis independent of estrogens

Autoimmune hepatitis (AIH) is a typical T cell-mediated chronic liver disease with a higher incidence in females. However, the molecular mechanism for the female predisposition is poorly understood. Estrogen sulfotransferase (Est) is a conjugating enzyme best known for its function in sulfonating and deactivating estrogens. The goal of this study is to investigate whether and how Est plays a role in the higher incidence of AIH in females. Concanavalin A (ConA) was used to induce T cell-mediated hepatitis in female mice. We first showed that Est was highly induced in the liver of ConA-treated mice. Systemic or hepatocyte-specific ablation of Est, or pharmacological inhibition of Est, protected female mice from ConA-induced hepatitis regardless of ovariectomy, suggesting the effect of Est inhibition was estrogen independent. In contrast, we found that hepatocyte-specific transgenic reconstitution of Est in the whole-body Est knockout (EstKO) mice abolished the protective phenotype. Upon the ConA challenge, EstKO mice exhibited a more robust inflammatory response with elevated production of proinflammatory cytokines and changed liver infiltration of immune cells. Mechanistically, we determined that ablation of Est led to the hepatic induction of lipocalin 2 (Lcn2), whereas ablation of Lcn2 abolished the protective phenotype of EstKO females. Our findings demonstrate that hepatocyte Est is required for the sensitivity of female mice to ConA-induced and T cell-mediated hepatitis in an estrogen-independent manner. Est ablation may have protected female mice from ConA-induced hepatitis by upregulating Lcn2. Pharmacological inhibition of Est might be a potential strategy for the treatment of AIH.

Polymeric immunoglobulin receptor deficiency exacerbates autoimmune hepatitis by inducing intestinal dysbiosis and barrier dysfunction

Autoimmune hepatitis (AIH) is an immune-mediated inflammatory liver disease with unclear pathogenesis. The gut microbiota and intestinal barrier play an essential role in AIH. Polymeric immunoglobulin receptor (pIgR) is a central component of mucosal immunity. Herein, we aimed to test the hypothesis that pIgR plays a pivotal role in maintaining gut microbiota homeostasis and gut barrier integrity in an AIH mouse model. The expression of intestinal pIgR shows the variation tendency of falling after rising with the aggravation of experimental AIH (EAH). The deletion of Pigr exacerbates liver damage in EAH. Furthermore, we identified a distinct microbiota profile of Pigr-deficient EAH mice, with a significant increased aboundance in the Oscillospiraceae family, particularly the Anaeromassilibacillus genus. Such a situation occurs because the loss of Pigr inhibits MEK/ERK, a key signal pathway whereby pIgR transports immunoglobulin A (IgA), resulting in reduced IgA secretion, which leads to the destruction of intestinal epithelial tight junction proteins and intestinal flora disturbance. Increased intestinal leakage causes increased translocation of bacteria to the liver, thus aggravating liver inflammation in EAH. Treatment with the Lactobacillus rhamnosus GG supernatant reverses liver damage in EAH mice but loses its protective effect without pIgR. Our study identifies that intestinal pIgR is a critical regulator of the adaptive response to S100-induced alterations in gut flora and the gut barrier function, which closely correlates with liver injury. Intestinal upregulation of pIgR could be a novel approach for treating AIH.

Liver infiltration of multiple immune cells during the process of acute liver injury and repair

BACKGROUND

Immune cells, including neutrophils, natural killer (NK) cells, T cells, NKT cells and macrophages, participate in the progression of acute liver injury and hepatic recovery. To date, there has been no systematic study on the quantitative changes in these different immune cells from initial injury to subsequent recovery.

AIM

To investigate the infiltration changes of various immune cells in acute liver injury models over time, and to study the relationship between the changes in leukocyte cell-derived chemotaxin 2 (LECT2) and the infiltration of several immune cells.

METHODS

Carbon tetrachloride- and concanavalin A-induced acute liver injury models were employed to mimic toxin-induced and autoimmune-mediated liver injury respectively. The quantitative changes in various immune cells were monitored at different time points. Serum samples were collected, and liver tissues were harvested. Ly6G, CD161, CD4, CD8 and F4/80 staining were used to indicate neutrophils, NK/NKT cells, CD4⁺ T cells, CD8⁺ T cells and macrophages, respectively. Lect2-KO mice were used to detect the function of LECT2.

RESULTS

During the injury and repair process, different types of immune cells began to increase, reached their peaks and fell into decline at different time points. Furthermore, when the serum alanine transaminase (ALT) and aspartate transaminase (AST) indices reverted to normal levels 7 d after the injury, the infiltration of immune cells still existed even 14 d after the injury, showing an obvious lag effect. We found that the expression of LECT2 was upregulated in acute liver injury mouse models, and the liver injuries of Lect2-KO mice were less severe than those of wild-type mice. Compared with wild-type mice, Lect2-KO mice had different immune cell infiltration.

CONCLUSION

The recovery time of immune cells was far behind that of serum ALT and AST during the process of liver repair. LECT2 could regulate monocyte/macrophage chemotaxis and might be used as a therapeutic target for acute liver injury.

HLA-related genetic susceptibility in autoimmune hepatitis according to autoantibody profile

Although the prevalence of autoimmune hepatitis in first-degree relatives is small, the relationship between genetic markers, especially human leucocyte antigens (HLA), and susceptibility to this disease, has been studied for over three decades. The genetic susceptibility to AIH is believed to be different in the two subtypes of the disease, AIH type 1 and AIH type 2. Type 1 AIH has anti-smooth muscle and anti-nuclear antibodies as its main markers, while those of type 2 AIH are the anti-liver/kidney microsome type 1 and anti-liver cytosol type 1 antibodies. The anti-soluble liver antigen/liver-pancreas antibodies, which, in addition to being present in both subtypes, mark an important number of patients without serological markers. Therefore, a third type of disease is questionable. The vast majority of immunogenetic studies compare the differences between the two main types and make no difference between which antibodies are present to define the subtype. This review seeks to analyze what was most important published in the AIH in this context, trying to relate the HLA alleles according to the AIH marker autoantibodies.

The double-sided of human leukocyte antigen-G molecules in type 1 autoimmune hepatitis

The immunomodulatory effects of HLA-G expression and its role in cancers, human liver infections and liver transplantation are well documented, but so far, there are only a few reports addressing autoimmune liver diseases, particularly autoimmune hepatitis (AIH).

Type 2 autoimmune hepatitis: Genetic susceptibility

Two types of autoimmune hepatitis (AIH) are recognized; AIH-1 is characterized by the presence of anti-nuclear and/or anti-smooth muscle autoantibodies, while AIH-2 is associated with the presence of anti-Liver kidney microsome and/or anti-Liver Cytosol antibodies. The autoantigens targeted by AIH-2 autoantibodies are the cytochrome P450 2D6 and Formiminotransferase-cyclodeaminase for anti-LKM1 and anti-LC1 respectively. Both autoantigens are expressed in hepatocytes at higher levels than in any other cell type. Therefore, compared to AIH-1, the autoantigens targeted in AIH-2 are predominantly tissue-specific. Distinct clinical features are specific to AIH-2 compared to AIH-1, including diagnosis in younger patients (mean age 6.6 years), onset as fulminant hepatitis in very young patients (3 years of age or less), higher frequency in children than in adults and is frequently associated with extrahepatic T cell-mediated autoimmune diseases. AIH-2 is also often diagnosed in patients with primary immunodeficiency. AIH-2 is associated with specific HLA class II susceptibility alleles; DQB1*0201 is considered the main determinant of susceptibility while DRB1*07/DRB1*03 is associated with the type of autoantibody present. HLA DQB1*0201 is in strong linkage disequilibrium with both HLA DRB1*03 and DRB1*07. Interestingly, as in humans, MHC and non-MHC genes strongly influence the development of the disease in an animal model of AIH-2. Altogether, these findings suggest that AIH-2 incidence is likely dependent on specific genetic susceptibility factors combined with distinct environmental triggers.

HLA, gut microbiome and hepatic autoimmunity

Genetic susceptibility to autoimmune liver diseases is conferred mainly by polymorphisms of genes encoding for the human leukocyte antigens (HLA). The strongest predisposition to autoimmune hepatitis type 1 (AIH-1) is linked to the allele DRB1*03:01, possession of which is associated with earlier disease onset and more severe course. In populations where this allele is very rare, such as in Asia, and in DRB1*03-negative patients, risk of AIH-1 is conferred by DRB1*04, which is associated with later disease onset and milder phenotype. AIH type 2 (AIH-2) is associated with DRB1*07. The pediatric condition referred to as autoimmune sclerosing cholangitis (ASC), is associated with the DRB1*13 in populations of Northern European ancestry. DRB1*1501 is protective from AIH-1, AIH-2 and ASC in Northern European populations. Possession of the DRB1*08 allele is associated with an increased risk of primary biliary cholangitis (PBC) across different populations. DRB1*03:01 and B*08:01 confer susceptibility to primary sclerosing cholangitis (PSC), as well as DRB1*13 and DRB1*15 in Europe. The hepatic blood supply is largely derived from the splanchnic circulation, suggesting a pathophysiological role of the gut microbiome. AIH appears to be associated with dysbiosis, increased gut permeability, and translocation of intestinal microbial products into the circulation; molecular mimicry between microbial and host antigens may trigger an autoaggressive response in genetically-predisposed individuals. In PBC an altered enteric microbiome may affect intestinal motility, immunological function and bile secretion. Patients with PSC have a gut microbial profile different from health as well as from patients with inflammatory bowel disease without PSC.

Metabolic heterogeneity caused by HLA-DRB1*04:05 and protective effect of inosine on autoimmune hepatitis

Autoimmune hepatitis (AIH) is an autoimmune disease caused by disruption of liver immune homeostasis. Genetic studies have revealed the predisposition of AIH with the human leukocyte antigen (HLA) region. Recently, metabolomics integrated with genomics has identified many genetic loci of biomedical interest. However, there is no related report in AIH. In the present study, we found that HLA-DRB1*04:05 was linked to the clinical features and prognosis of AIH in Chinese patients. Furthermore, our patients were divided into DRB1*04:05 positive and DRB1*04:05 negative groups and the metabolic profiling was done by HPLC/MS. We chose inosine, one of the highly altered metabolites, to explore the effect on an acute severe hepatitis murine model. The results showed that inosine treatment attenuated hepatocyte apoptosis, enhanced antioxidant ability and inhibited the activation and glycolysis of CD4⁺ T cell. We propose that inosine participates in the regulation of AIH through its protective effect on hepatocytes and inhibition of overactivated immune cells, which might provide a potential novel approach in treating acute form of AIH.

AhR Activation Leads to Attenuation of Murine Autoimmune Hepatitis: Single-Cell RNA-Seq Analysis Reveals Unique Immune Cell Phenotypes and Gene Expression Changes in the Liver

The aryl hydrocarbon receptor (AhR) is a ubiquitously expressed ligand-activated transcription factor. While initially identified as an environmental sensor, this receptor has been shown more recently to regulate a variety of immune functions. AhR ligands vary in structure and source from environmental chemicals such as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and indoles found in cruciferous vegetables to endogenous ligands derived from tryptophan metabolism. In the current study, we used TCDD, a high affinity AhR ligand to study the impact of AhR activation in the murine model of autoimmune hepatitis (AIH). Primarily, we used single-cell RNA-sequencing (scRNA-seq) technology to study the nature of changes occurring in the immune cells in the liver at the cellular and molecular level. We found that AhR activation attenuated concanavalin A (ConA)-induced AIH by limiting chemotaxis of pro-inflammatory immune cell subsets, promoting anti-inflammatory cytokine production, and suppressing pro-inflammatory cytokine production. scRNA-seq analysis showed some unusual events upon ConA injection such as increased presence of mature B cells, natural killer (NK) T cells, CD4+ or CD8+ T cells, Kupffer cells, memory CD8+ T cells, and activated T cells while TCDD treatment led to the reversal of most of these events. Additionally, the immune cells showed significant alterations in the gene expression profiles. Specifically, we observed downregulation of inflammation-associated genes including Ptma, Hspe1, and CD52 in TCDD-treated AIH mice as well as alterations in the expression of migratory markers such as CXCR2. Together, the current study characterizes the nature of inflammatory changes occurring in the liver during AIH, and sheds light on how AhR activation during AIH attenuates liver inflammation by inducing phenotypic and genotypic changes in immune cells found in the liver.

Transcriptomic profiling of blood from autoimmune hepatitis patients reveals potential mechanisms with implications for management

Autoimmune hepatitis (AIH) is a poorly understood, chronic disease, for which corticosteroids are still the mainstay of therapy and most patients undergo liver biopsy to obtain a diagnosis. We aimed to determine if there was a transcriptomic signature of AIH in the peripheral blood and investigate underlying biologic pathways revealed by gene expression analysis. Whole blood RNA from 75 AIH patients and 25 healthy volunteers was extracted and sequenced. Differential gene expression analysis revealed 249 genes that were significantly differentially expressed in AIH patients compared to controls. Using a random forest algorithm, we determined that less than 10 genes were sufficient to differentiate the two groups in our cohort. Interferon signaling was more active in AIH samples compared to controls, regardless of treatment status. Pegivirus sequences were detected in five AIH samples and 1 healthy sample. The gene expression data and clinical metadata were used to determine 12 genes that were significantly associated with advanced fibrosis in AIH. AIH patients with a partial response to therapy demonstrated decreased evidence of a CD8+ T cell gene expression signal. These findings represent progress in understanding a disease in need of better tests, therapies, and biomarkers.

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.

Myeloid-Derived Suppressive Cells Deficient in Liver X Receptor α Protected From Autoimmune Hepatitis

Myeloid-derived suppressor cells (MDSCs) emerge as a promising candidate for the immunotherapy of autoimmune hepatitis (AIH). However, targets for modulating MDSC in AIH are still being searched. Liver X receptors (LXRs) are important nuclear receptors linking lipid metabolism and immune responses. Despite the extensive studies of LXR in myeloid compartment, its role in MDSCs is currently less understood. Herein, expression of LXRα was found to be upregulated in AIH patients and colocalized with hepatic MDSCs. In ConA-induced hepatitis, deletion of LXRα led to increased expansion of MDSCs in the liver and alleviated the hepatic injury. MDSCs in LXRα-/- mice exhibited enhanced proliferation and survival comparing with WT mice. T-cell proliferation assay and adoptive cell transfer experiment validated the potent immunoregulatory role of MDSCs in vitro and in vivo. Mechanistically, MDSCs from LXRα-/- mice possessed significantly lower expression of interferon regulatory factor 8 (IRF-8), a key negative regulator of MDSC differentiation. Transcriptional activation of IRF-8 by LXRα was further demonstrated.

Conclusion

We reported that abrogation of LXRα facilitated the expansion of MDSCs via downregulating IRF-8, and thereby ameliorated hepatic immune injury profoundly. Our work highlights the therapeutic potential of targeting LXRα in AIH.

Inhibition of miR-431-5p attenuated liver apoptosis through KLF15/p53 signal pathway in S100 induced autoimmune hepatitis mice

AIMS

The purpose of this study was to investigate the effects of miR-431-5p on hepatocyte apoptosis in AIH.

MATERIALS AND METHODS

We used intraperitoneal injection of S100 to establish AIH mouse model and injected AAV into tail vein on day 14 of modeling to regulate miR-431-5p expression. The expression of ALT, AST, IgG and apoptosis-related proteins Bax, Bcl-2 and cleaved caspase 3 were measured in each group. Cellular experiments were performed using miR-431-5p mimics or inhibitors to transfect LPS-stimulated AML12 cells, and apoptosis was verified using Western blot and Hoechst 33342/PI Double Staining. The target of miR-431-5p, KLF15, was screened using databases and verified by the luciferase reporter assay. The relationship between KLF15 and p53 was verified by si-KLF15 and PFTβ (a p53-specific inhibitor).

KEY FINDINGS

Here, we observed that the increase in the level of miR-431-5p was accompanied by a decrease in the expression of Krüppel-like zinc finger transcription factor 15 (KLF15). In addition, the deletion of miR-431-5p significantly reduced hepatocyte apoptosis in AIH mice induced by liver S100 and apoptosis of AML12 cells induced by LPS stimulation, accompanied by decreased expression of Bax and cleaved caspase-3 as well as increased expression of Bcl-2. Moreover, KLF15 was the direct and functional target of miR-431-5p. Furthermore, miR-431-5p negatively regulated the expression of KLF15, and KLF15 deletion partially abolished the inhibitory effect of miR-431-5p deletion on apoptosis by activating p53 signaling.

SIGNIFICANCE

In summary, miR-431-5p may be a potential therapeutic target for AIH.

Autophagy, Mitophagy and MicroRNA Expression in Chronic Hepatitis C and Autoimmune Hepatitis

Although the role of autophagy has been implicated in several forms of chronic hepatitis, it is still not fully understood. Active autophagy eliminates damaged molecules and organelles (such as mitochondria) by lysosomal degradation. In the present study, we aimed to examine and compare autophagy activity in chronic hepatitis C (CHC) and autoimmune hepatitis (AIH) by detecting the expression of autophagy (LC3 and p62) and mitochondrium-related (TOMM20) proteins, as well as the levels of selected microRNAs (miR-101, -155, -204 and - 224) known to be involved in the regulation of autophagy. In addition, the expression levels were related to pathohistological parameters. Liver biopsy samples, including 45 CHC and 18 AIH cases, were immunohistochemically stained for LC3, p62 and TOMM20 and the expression of miRNAs was determined using real-time PCR. We found elevated LC3 and p62 in AIH samples as compared with CHC ones, indicating an activated autophagy that is impaired in AIH as no degradation of p62 seemed to occur. Moreover, p62 showed strong correlation with necroinflammatory grades in the AIH group. The observed elevated levels of TOMM20 and p62 suggest a less efficient elimination of damaged mitochondria in AIH as opposed to CHC, in which autophagy seems to have a more active function. The level of miR-101 was increased in case of CHC as compared with AIH, however, miR-155, -204 and 224 resulted in no expressional. Furthermore, miR-224 level correlated with steatosis and miR-155 expression with fibrosis stage in CHC. In conclusion, dissimilar autophagic activity was observed in CHC and AIH, suggesting a close association between impaired autophagy and severity of necroinflammation. This impairment may not be regulated by the analyzed miRNAs. Nevertheless, miR-224 and - 155 seem to be associated with CHC progression.

Examining pathogenic concepts of autoimmune hepatitis for cues to future investigations and interventions

BACKGROUND

Multiple pathogenic mechanisms have been implicated in autoimmune hepatitis, but they have not fully explained susceptibility, triggering events, and maintenance or escalation of the disease. Furthermore, they have not identified a critical defect that can be targeted. The goals of this review are to examine the diverse pathogenic mechanisms that have been considered in autoimmune hepatitis, indicate investigational opportunities to validate their contribution, and suggest interventions that might evolve to modify their impact. English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed. Genetic and epigenetic factors can affect susceptibility by influencing the expression of immune regulatory genes. Thymic dysfunction, possibly related to deficient production of programmed cell death protein-1, can allow autoreactive T cells to escape deletion, and alterations in the intestinal microbiome may help overcome immune tolerance and affect gender bias. Environmental factors may trigger the disease or induce epigenetic changes in gene function. Molecular mimicry, epitope spread, bystander activation, neo-antigen production, lymphocytic polyspecificity, and disturbances in immune inhibitory mechanisms may maintain or escalate the disease. Interventions that modify epigenetic effects on gene expression, alter intestinal dysbiosis, eliminate deleterious environmental factors, and target critical pathogenic mechanisms are therapeutic possibilities that might reduce risk, individualize management, and improve outcome. In conclusion, diverse pathogenic mechanisms have been implicated in autoimmune hepatitis, and they may identify a critical factor or sequence that can be validated and used to direct future management and preventive strategies.

Association of Interleukin-6 and Interleukin-1 Family Gene Polymorphisms in Autoimmune Hepatitis

INTRODUCTION AND AIM

Autoimmune hepatitis (AIH) is an immune-mediated destruction of liver cells, in recognition of interface hepatitis, seropositivity for autoantibodies, and interface hepatitis in histology sections. Hepatocyte destruction in AIH is the direct result of CD4+ T-cell destruction. Yet, Th17 mediated immune attach and a diversity of cytokine networks, including pro-inflammatory cytokines such as Interleukin 1 (IL-1) and Interleukin 6 (IL-6), set the stage for the destructive liver damage.

MATERIAL AND METHOD

Peripheral blood samples from 57 patients, with AIH, recruited from referrals to the main pediatric hospital in Tehran. Single nucleotide polymorphisms for the following cytokines genes, were evaluated through, polymerase chain reaction with sequencespecific primers (PCR-SSP) assay: IL-1a (C/T -889), IL-1α (C/T -511), IL-1β (C/T +3962), IL-1 receptor (IL-1R; C/T Pst-I 1970), IL-1RA (C/T Mspa-I 11100), and IL-6 (C/G -174 and A/G nt565).

RESULTS

Significant higher frequency of genotype AA was detected in patients in IL-6 at position nt565 (15.8% in AIH patients vs. 2.9% in controls, p = 0.003). The haplotype GA of IL-6 at -174 and nt565, was significantly overrepresented in the AIH group, compared to (20.9% of AIH vs. 1.4% in controls p < 0.0001).

CONCLUSION

Results of our study, indicate significant deviation toward high yield IL-6 polymorphisms, in AIH patients. These data could bring new insights in pathophysiology of disease, which could contribute to developing novel treatments for AIH.

Analytical "bake-off" of whole genome sequencing quality for the Genome Russia project using a small cohort for autoimmune hepatitis

A comparative analysis of whole genome sequencing (WGS) and genotype calling was initiated for ten human genome samples sequenced by St. Petersburg State University Peterhof Sequencing Center and by three commercial sequencing centers outside of Russia. The sequence quality, efficiency of DNA variant and genotype calling were compared with each other and with DNA microarrays for each of ten study subjects. We assessed calling of SNPs, indels, copy number variation, and the speed of WGS throughput promised. Twenty separate QC analyses showed high similarities among the sequence quality and called genotypes. The ten genomes tested by the centers included eight American patients afflicted with autoimmune hepatitis (AIH), plus one case’s unaffected parents, in a prelude to discovering genetic influences in this rare disease of unknown etiology. The detailed internal replication and parallel analyses allowed the observation of two of eight AIH cases carrying a rare allele genotype for a previously described AIH-associated gene (FTCD), plus multiple occurrences of known HLA-DRB1 alleles associated with AIH (HLA-DRB1-03:01:01, 13:01:01 and 7:01:01). We also list putative SNVs in other genes as suggestive in AIH influence.

Association of TNF-α-308 Polymorphism with Susceptibility to Autoimmune Hepatitis in Tunisians

Autoimmune hepatitis (AIH) is a chronic hepatitis of unknown etiology and several proinflammatory cytokines are implicated in its pathogenesis. The association of TNF-α gene polymorphism with AIH onset is not fully elucidated especially in the Tunisian population. The aim of this study was to determine the association of TNF-α (-308 G > A) polymorphism with AIH susceptibility and with TNF-α expression or clinical manifestations of AIH. A total of 50 AIH patients and 150 controls were included. Evaluation of TNF-α polymorphism was performed by ARMS PCR method. A significantly higher frequence of the AA genotype was found in AIH patients compared to controls (34 vs. 8%, p = 0.00002, OR 5.88). The frequency of the A-allele was significantly higher in patients with AIH compared to controls (55 vs. 37.3%, p = 0.002, OR 2.05). The G-allele was significantly more frequent in healthy controls compared to AIH patients [43 vs. 61.3%, p = 0.001, OR 0.47 (0.3-0.75)]. There was a positive correlation between the A/A genotype and a higher serum expression of TNF-α. The TNF*A allele confer susceptibility to AIH in the Tunisian patients and is associated with increased production of TNF-α. Anti-TNF antibodies could be an alternative to the use of corticotherapy and may avoid the exacerbated immune response in AIH.

Involvement of the Nrf2/HO-1/CO axis and therapeutic intervention with the CO-releasing molecule CORM-A1, in a murine model of autoimmune hepatitis

Concanavalin A (ConA)-induced hepatitis is an experimental model of human autoimmune hepatitis induced in rodents by i.v. injection of Con A. The disease is characterized by increase in serum levels of transaminases and massive immune infiltration of the livers. Type 1, type 2, and type 17 cytokines play a pathogenic role in the development of ConA-induced hepatitis. To understand further the immunoregulatory mechanisms operating in the development and regulation of ConA-induced hepatitis, we have evaluated the role of the anti-inflammatory pathway Nrf2/HO-1/CO (Nuclear Factor E2-related Factor 2/Heme Oxygenase-1/Carbon Monoxide) in this condition and determined whether the in vivo administration of CO via the CO-releasing molecule (CORM) CORM-A1, influences serological and histological development of Con-A-induced hepatitis. We have firstly evaluated in silico the genes belonging to the Nrf2/HO-1/CO pathway that are involved in the pathogenesis of autoimmune hepatitis (AIH). The data obtained from the in silico study demonstrate that a significant number of genes modulated in the liver of ConA-challenged mice belong to the Nrf2 pathway; on the other hand, the administration of CORM-A1 determines an improvement in several sero-immunological and histological parameters, and it is able to modulate genes identified by the in silico analysis. Collectively, our data indicate that the Nrf2/HO-1/CO pathway is fundamental for the regulation of the immune responses, and that therapeutic intervention aimed at its modulation by CORM-A1 may represent a valuable strategy to be considered for the treatment of autoimmune hepatitis in humans.

Influence of TBX21 T-1993C variant on autoimmune hepatitis development by Yin-Yang 1 binding

AIM

To investigated the mechanism of the association between the TBX21 T-1993C promoter polymorphism and autoimmune hepatitis type 1 (AIH-1) development.

METHODS

In vivo, In vivo, and reporter analyses were performed to determine the function of transcription factors binding to the T-1993C element of the TBX21 promoter in human CD4⁺ T and B cell lines. Flow cytometry and quantitative real-time PCR were used to analyze T-box transcription factor (T-bet) and interferon-γ (IFN-γ) expressions in CD4⁺ T cells, B cells and monocytes from the peripheral blood of AIH-1 patients including 5-1993TC and 15-1993TT genotype carriers, and healthy controls including 10-1993TC and 25-1993TT genotype carriers. Furthermore, a range of biochemical indices was measured simultaneously in the blood of AIH-1 patients.

RESULTS

TBX21-1993C allele created a strong Yin-Yang 1 (YY1)-binding site and decreased transcriptional activity of TBX21 promoter in human CD4⁺ T and B cells. Higher levels of T-bet and IFN-γ were detected in the circulating CD4⁺ T cells and B cells of AIH-1 patients carrying the TBX21-1993 TT genotype compared with the patients carrying the -1993 TC genotype and controls with the -1993 TC genotype. T-bet expression levels of circulating T cells and B cells were positively correlated with AIH-1 disease activity. Knockdown of YY1 with siRNA caused increased expression of T-bet and IFN-γ in peripheral blood mononuclear cells in AIH-1 patients.

CONCLUSION

The repression of TBX21 expression by high-affinity binding of YY1 to the -1993C allele may contribute to a decreased development of AIH-1 via suppression of type 1 immunity.

Serum microRNA profiles in patients with chronic hepatitis B, chronic hepatitis C, primary biliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitis, or drug-induced liver injury

PURPOSE

Some blood biomarkers or histological examination by liver biopsy are used for the diagnosis of liver diseases in clinics. However, conventional blood biomarkers show poor specificity and sensitivity, and liver biopsy is highly invasiveness. Therefore, to overcome such disadvantages, specific/sensitive and noninvasive options are desirable. In recent years, circulating microRNAs (miRNAs) have been acknowledged for their potential as disease markers. Actually, several miRNAs have been reported to be biomarker candidates of liver diseases. However, these earlier studies were performed for one disease. Therefore, the specificity as biomarkers was not guaranteed, because they didn't study for the other types of liver injury. In this study, we examined if circulating miRNA could distinguish different types of liver diseases.

METHODS

Serum miRNA profiles in 28 patients with chronic hepatitis B, chronic hepatitis C, primary biliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitis or drug-induced liver injury as well as 4 control subjects were determined by TaqMan MicroRNA Array analysis. Principal component analysis (PCA) of selected miRNAs was performed.

RESULTS

We identified 37 miRNAs whose levels were significantly different between any of the groups. Although individual miRNAs could not distinguish different types of liver diseases, probably because of similar liver pathology, their profiling by PCA could classify different liver disease groups.

CONCLUSIONS

The profiling of the selected miRNAs can be useful to distinguish different types of liver diseases.

rs10499194 polymorphism in the tumor necrosis factor-α inducible protein 3 (TNFAIP3) gene is associated with type-1 autoimmune hepatitis risk in Chinese Han population

Previous studies have found that the polymorphisms of tumor necrosis factor-α induced protein 3 (TNFAIP3) were associated with several autoimmune diseases. However, the role of TNFAIP3 polymorphisms in type-1 autoimmune hepatitis (AIH-1) remained unclear. The present study aimed to clarify the association of TNFAIP3 polymorphisms with AIH-1 risk in a Chinese Han population. The TaqMan SNP genotyping assay was used to determine the distribution of TNFAIP3 polymorphisms in 432 AIH-1 patients and 500 healthy controls. The association of TNFAIP3 polymorphisms and clinical characteristic was further evaluated. Five TNFAIP3 polymorphisms (rs2230926, rs5029939, rs10499194, rs6920220, rs582757) were analyzed in the present study. No significant association could be observed between rs2230926, rs5029939, rs6920220, rs582757 and the susceptibility to AIH-1 in Chinese Han population. Compared with wild-type genotype CC at rs10499194, individuals carrying CT genotype had a significantly increased risk for developing AIH-1 (OR = 2.32, 95%CI 1.44-3.74). Under a dominant model, CT/TT carriers have a 140% increased risk of AIH-1 than CC carriers (OR = 2.40, 95%CI 1.50-3.87). The rs10499194 T allele was also found to be significantly associated with AIH-1 risk (OR = 2.41, 95%CI 1.51-3.82). In addition, higher serum ALT, AST levels and more common cirrhosis were observed in AIH-1 patients with T allele (CT/TT) than those with CC genotype. In conclusion, TNFAIP3 rs10499194 T allele and CT genotype were associated with an increased risk for AIH-1, suggesting rs10499194 polymorphism as a candidate of susceptibility locus to AIH-1.

Immunopathogenic Mechanisms of Autoimmune Hepatitis: How Much Do We Know from Animal Models?

Autoimmune hepatitis (AIH) is characterized by a progressive destruction of the liver parenchyma and a chronic fibrosis. The current treatment of autoimmune hepatitis is still largely dependent on the administration of corticosteroids and cytostatic drugs. For a long time the development of novel therapeutic strategies has been hampered by a lack of understanding the basic immunopathogenic mechanisms of AIH and the absence of valid animal models. However, in the past decade, knowledge from clinical observations in AIH patients and the development of innovative animal models have led to a situation where critical factors driving the disease have been identified and alternative treatments are being evaluated. Here we will review the insight on the immunopathogenesis of AIH as gained from clinical observation and from animal models.

A Macrophage Migration Inhibitory Factor Polymorphism Is Associated with Autoimmune Hepatitis Severity in US and Japanese Patients

BACKGROUND

The pathogenesis of autoimmune hepatitis (AIH) is incompletely understood. Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine implicated in the pathophysiology of multiple autoimmune diseases. We recently reported that MIF expression was increased in a US AIH cohort. MIF expression in non-Western AIH patients is unknown. A MIF-173 GC single nucleotide polymorphism in the MIF promoter (rs755622) is clinically associated with steroid resistance in several inflammatory disorders but has not been evaluated in AIH.

AIM

To compare MIF polymorphisms and their relationship to clinical parameters in AIH patients from the USA and Japan.

METHODS

DNA and matched sera from AIH patients and healthy controls from Japan (N = 52) were compared to the US group. Serum concentrations of MIF and its circulating receptor CD74 were measured by ELISA. MIF-173 GC (rs755622) and MIF-794 CATT_5-8 (rs5844572) polymorphisms were analyzed by standard methods. MIF genotypes were correlated with serum ALT and steroid requirements.

RESULTS

Serum MIF was increased in Japanese AIH patients versus local controls, in agreement with the US AIH patients. Within both AIH groups, ALT was higher in CC/GC versus GG patients. Further, the steroid requirement was higher in AIH patients with GC/CC genotypes from both groups. In the Japanese patient group, the GC/CC genotype also was associated with acute symptomatic presentation.

CONCLUSIONS

The MIF-173 CC/GC genotypes may be associated with both higher ALT and maintenance steroid requirements in AIH patients from the USA and Japan. This polymorphism could be a marker of disease severity in AIH patients.

The pseudokinase MLKL mediates programmed hepatocellular necrosis independently of RIPK3 during hepatitis

Although necrosis and necroinflammation are central features of many liver diseases, the role of programmed necrosis in the context of inflammation-dependent hepatocellular death remains to be fully determined. Here, we have demonstrated that the pseudokinase mixed lineage kinase domain-like protein (MLKL), which plays a key role in the execution of receptor-interacting protein (RIP) kinase-dependent necroptosis, is upregulated and activated in human autoimmune hepatitis and in a murine model of inflammation-dependent hepatitis. Using genetic and pharmacologic approaches, we determined that hepatocellular necrosis in experimental hepatitis is driven by an MLKL-dependent pathway that occurs independently of RIPK3. Moreover, we have provided evidence that the cytotoxic activity of the proinflammatory cytokine IFN-γ in hepatic inflammation is strongly connected to induction of MLKL expression via activation of the transcription factor STAT1. In summary, our results reveal a pathway for MLKL-dependent programmed necrosis that is executed in the absence of RIPK3 and potentially drives the pathogenesis of severe liver diseases.

Autoantibody presentation in drug-induced liver injury and idiopathic autoimmune hepatitis: the influence of human leucocyte antigen alleles

OBJECTIVES

Positive autoantibody (AAB) titres are commonly encountered in autoimmune hepatitis (AIH) and in a proportion of drug-induced liver injury (DILI) patients. The underlying mechanism for selective AAB occurrence in DILI is unknown, but could be associated with variations in immune-associated genes. Hence, we aimed to analyse human leucocyte antigen (HLA) allele compositions in DILI with positive (+) and negative (-) AAB titres and in AIH patients.

METHODS

High-resolution genotyping of HLA class I (A, B, C) and II (DRB1, DQB1) loci was performed on 207 DILI and 50 idiopathic AIH patients and compared with 885 healthy Spanish controls.

RESULTS

Compared with controls, HLA-B*08:01 [44 vs. 9.7%, P=3.7E-13/corrected P-value (Pc)=1.0E-11], C*07:01 (46 vs. 24%, P=6.4E-04/Pc=0.012), DRB1*03:01 (58 vs. 21.5%, P=5.0E-09/Pc=1.0E-07) and DQB1*02:01 (56 vs. 22%, P=6.8E-08/Pc=9.0E-07) were significantly more frequent in AIH patients. The HLA-A*01:01 frequency was increased in the same population, but did not reach significance after Bonferroni's correction (34 vs. 19%, P=0.02/Pc=0.37). Fifty-eight of 207 DILI patients presented positive titres for at least one AAB (predominantly antinuclear antibody 76% and antismooth muscle antibody 28%). There was a tendency towards higher representation of DRB1*14:01 and DQB1*05:03 in DILI AAB+ compared with DILI AAB- (13.8 vs. 4.0%, P=0.02/Pc=0.5; 13.8 vs. 4.7%, P=0.04/Pc=0.5).

CONCLUSION

The presence of HLA alleles B*08:01, C*07:01, DRB1*03:01, DQB1*02:01 and possibly A*01:01 enhances the risk of AIH (type 1) in Spanish patients. These alleles form part of the ancestral haplotype 8.1. HLA-DRB1*14:01 and DQB1*05:03 could potentially increase the risk of positive AAB (particularly antinuclear antibody) in Spanish DILI patients.

Familial occurrence of autoimmune liver disease with overlapping features of primary biliary cholangitis and autoimmune hepatitis in a mother and her daughter

We encountered two patients with overlapping features of primary biliary cholangitis and autoimmune hepatitis within the same family. A 68-year-old woman presented at our hospital from a previous medical institution because of the diagnosis of primary biliary cholangitis. Her 49-year-old daughter was admitted with liver dysfunction 4 years later. When compared, these two related patients were found to have overlapping features of primary biliary cholangitis and autoimmune hepatitis. Their human leukocyte antigen haplotype was DRB1*04:05/DRB1*15:02. The clinical and biochemical findings of these two patients immediately improved following treatment with a combination of prednisolone and ursodeoxycholic acid, in accordance with the Japanese guidelines. It is extremely important to identify such pathological conditions as quickly as possible, particularly with the appearance of severe liver dysfunction due to liver cirrhosis, as observed in our case. The Japanese guidelines are considered to be a realistic and useful clinical policy for the swift and efficient treatment of patients with overlapping features of primary biliary cholangitis and autoimmune hepatitis. We suggest that our two patients presented with a genetic predisposition to autoimmune liver disease with overlapping features of primary biliary cholangitis and autoimmune hepatitis within the same family.

Cutting edge issues in autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe liver disease affecting all age groups worldwide. Novel basic and clinical aspects of AIH, addressed at a Monothematic Conference in London in September 2015, are highlighted in this review. The diagnosis of AIH relies upon detection of characteristic autoantibodies, hypergammaglobulinemia, and interface hepatitis on liver histology. The International Autoimmune Hepatitis Group (IAIHG) has devised diagnostic scoring systems to help in comparative studies and clinical practice. AIH arises in a genetically predisposed host, when yet unknown triggers - such an encounter with a pathogen - lead to a T cell-mediated immune response targeting liver autoantigens. This immune response is inadequately controlled because regulatory mechanisms are impaired. The mainstay of treatment for AIH is immunosuppression, which should be instituted as soon as the diagnosis is made. Standard treatment regimens include relatively high doses of predniso(lo)ne, which are tapered gradually as azathioprine is introduced. Recent guidelines have described newer treatment regimens and have tightened the goal of therapy to complete normalization of biochemical, serological and histological parameters. Mycophenolate mofetil, calcineurin inhibitors, mTOR inhibitors and biological agents are potential salvage therapies, but should be reserved for selected non-responsive patients and administered only in experienced centers. Liver transplantation is a life-saving option for those patients who progress to end-stage liver disease. Further dissection of cellular and molecular pathways involved in AIH pathogenesis is likely to lead to the discovery of novel, tailored and better tolerated therapies.

Single-gene association between GATA-2 and autoimmune hepatitis: A novel genetic insight highlighting immunologic pathways to disease

Background & Aims Autoimmune hepatitis (AIH), an immune-mediated liver disease, originates as a consequence of interacting genetic and environmental risk factors. Treatment remains non-specific and prone to side effects. Deficiencies in regulatory T cell (Treg) function are hypothesized to contribute to the pathogenesis of AIH. Methods We describe an adult patient who presented with AIH in the context of monocytopenia. The patient was characterized by GATA2 gene sequencing, flow cytometry of peripheral blood for leucocyte subsets, ELISA for serum Flt-3 ligand, and immunohistochemistry of liver biopsy tissue. Results Sequencing confirmed a GATA2 mutation. Peripheral Treg were absent in the context of a preserved total T cell count. Immunostaining for the Treg transcription factor FOXP3 was reduced in liver tissue as compared to a control AIH specimen. There were marked deficiencies in multiple antigen-presenting cell subsets and Flt-3 ligand was elevated. These findings are consistent with previous reports of GATA2 dysfunction. Conclusions The association of a GATA2 mutation with AIH is previously unrecognized. GATA2 encodes a hematopoietic cell transcription factor, and mutations may manifest as monocytopenia, dendritic and B cell deficiencies, myelodysplasia, and immunodeficiency. Tregs may be depleted as in this case. Our findings provide support for the role of Tregs in AIH, complement reports of other deficiencies in T cell regulation causing AIH-like syndromes, and support the rationale of attempting to modulate the Treg axis for the therapeutic benefit of AIH patients.

Atg7 Knockdown Augments Concanavalin A-Induced Acute Hepatitis through an ROS-Mediated p38/MAPK Pathway

Concanavalin A (ConA), a T-cell mitogen that induces acute autoimmune hepatitis, is widely used to model pathophysiological processes of human acute autoimmune liver disease. Although autophagy has been extensively studied in the past decade, little is known about its molecular mechanism underlying the regulation of ConA-induced acute hepatitis. In this study, we used a Cre-conditional atg7 KO mouse to investigate the effects of Atg7-associated autophagy on ConA-induced murine hepatitis. Our results demonstrated that atg7 deficiency in mice enhanced macrophage activation and increased pro-inflammatory cytokines upon ConA stimulation. Atg7 silencing resulted in accumulation of dysfunctional mitochondria, disruption of reactive oxygen species (ROS) degradation, and increase in pro-inflammatory cytokines in Raw264.7 cells. p38/MAPK and NF-κB levels were increased upon ConA induction due to Atg7 deficiency. Blocking ROS production inhibited ConA-induced p38/IκB phosphorylation and subsequent intracellular inflammatory responses. Hence, this study demonstrated that atg7 knockout in mice or Atg7 knockdown in cell culture augmented ConA-induced acute hepatitis and related cellular malfunction, indicating protective effects of Atg7 on regulating mitochondrial ROS via a p38/MAPK-mediated pathway. Collectively, our findings reveal that autophagy may attenuate macrophage-mediated inflammatory response to ConA and may be the potential therapeutic targets for acute liver injury.

Using GWAS to identify genetic predisposition in hepatic autoimmunity

Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) represent the three major hepatic autoimmune conditions. Patient morbidity and mortality remain high across these three diseases, and an unmet need for rational therapy exists. Disease understanding has focused on combining clinical and laboratory based science to provide better insights into the joint host and environmental factors necessary for the initiation, and perpetuation, of hepato-biliary inflammation. Twin studies, family studies, population studies and an inter-relationship with other autoimmune phenomena suggest a genetic component to risk for each disease. Until recently, understanding of this genetic risk has been limited to HLA haplotypes. Associations with risk-conferring and protective HLA haplotypes are present in all three diseases. Over the last few years, genome-wide association studies (GWAS), and related genetic association studies, have greatly increased understanding of the genetic risk signature of these three diseases and autoimmunity in general. Here we consider the rationale for GWAS in general and with specific reference to hepatic autoimmunity. We consider the process of GWAS, and highlight major findings to date. Potential functional implications of key findings are discussed including the IL-12/STAT4 pathway in PBC and the CD28/IL-2 pathway in PSC. We describe the marked pleiotropy demonstrated by PBC and PSC, which is consistent with other autoimmune diseases. Further, we focus on specific gene associations including SH2B3, which is common to all three diseases, and FUT2 in PSC, which represents a link between environment and genetics. We review attempts to translate GWAS findings into basic laboratory models including in vivo systems and highlight where clinical observations relate to genetics. Finally we describe deficiencies in GWAS to date and consider future study of genetics in hepatic autoimmunity.

Genetic Risk and the Development of Autoimmune Liver Disease

Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) have collectively been recognized as autoimmune liver diseases. They have all been subjected to genome-wide association studies (GWAS) and several dozens susceptibility loci have been determined. The predominant feature of the genetic findings is that of a strong association with the human leukocyte antigen (HLA) and numerous weak associations scattered throughout the remainder of the genome. The non-HLA associations show some degree of overlap, not only between PBC, PSC and AIH, but also with other autoimmune and immune-mediated diseases. Mathematical modelling shows that the main fraction of autoimmune disease risk (including that of autoimmune liver diseases) is not explained by GWAS, proposing a major role of environmental factors. The HLA associations and autoantibodies observed in these conditions may hold clues as to the nature of such factors, which are exceedingly difficult to map by means of epidemiological study designs. The present review article explores the potential relationship between genetic risk as determined by GWAS and environmental risk in autoimmune liver diseases, and proposes a model for relevant thinking on the susceptibility genes in PBC, PSC and AIH.

Low Serum Hepcidin in Patients with Autoimmune Liver Diseases

Hepcidin, a liver hormone, is important for both innate immunity and iron metabolism regulation. As dysfunction of the hepcidin pathway may contribute to liver pathology, we analysed liver hepcidin mRNA and serum hepcidin in patients with chronic liver diseases. Hepcidin mRNA levels were determined in liver biopsies obtained from 126 patients with HCV (n = 21), HBV (n = 23), autoimmune cholestatic disease (primary biliary cirrhosis and primary sclerosing cholangitis; PBC/PSC; n = 34), autoimmune hepatitis (AIH; n = 16) and non-alcoholic fatty liver disease (NAFLD; n = 32). Sera sampled on the biopsy day from the same patients were investigated for serum hepcidin levels. Hepatic hepcidin mRNA levels correlated positively with ferritin and negatively with serum γ-GT levels. However, no correlation was found between serum hepcidin and either ferritin or liver hepcidin mRNA. Both serum hepcidin and the serum hepcidin/ferritin ratio were significantly lower in AIH and PBC/PSC patients’ sera compared to HBV, HCV or NAFLD (P<0.001 for each comparison) and correlated negatively with serum ALP levels. PBC/PSC and AIH patients maintained low serum hepcidin during the course of their two-year long treatment. In summary, parallel determination of liver hepcidin mRNA and serum hepcidin in patients with chronic liver diseases shows that circulating hepcidin and its respective ratio to ferritin are significantly diminished in patients with autoimmune liver diseases. These novel findings, once confirmed by follow-up studies involving bigger size and better-matched disease subgroups, should be taken into consideration during diagnosis and treatment of autoimmune liver diseases.

Sensitization to autoimmune hepatitis in group VIA calcium-independent phospholipase A2-null mice led to duodenal villous atrophy with apoptosis, goblet cell hyperplasia and leaked bile acids

Chronic bowel disease can co-exist with severe autoimmune hepatitis (AIH) in an absence of primary sclerosing cholangitis. Genetic background may contribute to this overlap syndrome. We previously have shown that the deficiency of iPLA2β causes an accumulation of hepatocyte apoptosis, and renders susceptibility for acute liver injury. We here tested whether AIH induction in iPLA2β-null mice could result in intestinal injury, and whether bile acid metabolism was altered. Control wild-type (WT) and female iPLA2β-null (iPLA2β(-/-)) mice were intravenously injected with 10mg/kg concanavalinA (ConA) or saline for 24h. ConA treatment of iPLA2β(-/-) mice caused massive liver injury with increased liver enzymes, fibrosis, and necrosis. While not affecting WT mice, ConA treatment of iPLA2β(-/-) mice caused severe duodenal villous atrophy concomitant with increased apoptosis, cell proliferation, globlet cell hyperplasia, and endotoxin leakage into portal vein indicating a disruption of intestinal barrier. With the greater extent than in WT mice, ConA treatment of iPLA2β(-/-) mice increased jejunal expression of innate response cytokines CD14, TNF-α, IL-6, and SOCS3 as well as chemokines CCL2 and the CCL3 receptor CCR5. iPLA2β deficiency in response to ConA-induced AIH caused a significant decrease in hepatic and biliary bile acids, and this was associated with suppression of hepatic Cyp7A1, Ntcp and ABCB11/Bsep and upregulation of intestinal FXR/FGF15 mRNA expression. The suppression of hepatic Ntcp expression together with the loss of intestinal barrier could account for the observed bile acid leakage into peripheral blood. Thus, enteropathy may result from acute AIH in a susceptible host such as iPLA2β deficiency.

[Auto-immune hepatitis in chronic granulomatous disease in a 2-year-old girl]

BACKGROUND

Chronic granulomatous disease is a rare inherited primary immune deficiency disease characterized by recurrent infection and an increased susceptibility to autoimmunity disorders. We report on the case of a girl with autoimmune hepatitis in chronic granulomatous disease to describe the clinical and biological features and treatment implications for patients with chronic granulomatous disease associated with autoimmune disorders.

CASE REPORT

An 18-month-old girl was referred to our department for investigation of hepatomegaly. She was the third child of non-consanguineous parents. Her two elder sisters had died from infectious diseases at an early age. She had elevated liver transaminase levels with a normal gamma globulin concentration. Negative results were found for all autoimmune markers (antinuclear antibody, anti-smooth muscle, anti-liver-kidney microsomal, anti-liver cytosol and anti-soluble liver antigen). Her liver biopsy showed features of interface hepatitis with portal fibrosis. The diagnosis of seronegative autoimmune hepatitis was established. Treatment with corticosteroids and azathioprine led to clinical improvement with normalization of transaminases. Six months after initial presentation, at the age of 2 years, she was readmitted for fever. Staphylococcus aureus bacteremia was identified with multiple foci of infection (skin infection, arthritis of the right elbow, pneumonia, buttock abscess). The immunological workup revealed chronic granulomatous disease. The course was marked by a fatal outcome despite appropriate antibiotics and intensive care.

CONCLUSION

Early diagnosis of the association between chronic granulomatous disease and autoimmune disorders allows for appropriate treatments, improves the quality of life for affected patients, and reduces the risk of mortality.

Autoimmune hepatitis: recent advances in the pathogenesis and new diagnostic guidelines in Japan

Autoimmune hepatitis (AIH) is thought to be associated with various genetic and immunological abnormalities. Concerning the pathogenesis of AIH, increasing attention has been paid to genome-wide association studies, toll-like receptors and Treg/Th17 balance. For Japanese patients with AIH, novel diagnostic guidelines have been proposed in view of the differential clinical features between Japanese and Caucasian patients. However, the diagnosis of some patients in acute hepatitis phase is not easy. Histologically, centrilobular necrosis without portal inflammation is particularly characteristic in the acute hepatitis phase. Some patients become resistant to steroid therapy and have a very poor prognosis once they progress to acute hepatic failure. Therefore, additional revision of the current diagnostic criteria, including severity grading, will be needed in the future.

Modeling toxicodynamic effects of trichloroethylene on liver in mouse model of autoimmune hepatitis

Chronic exposure to industrial solvent and water pollutant trichloroethylene (TCE) in female MRL+/+mice generates disease similar to human autoimmune hepatitis. The current study was initiated to investigate why TCE-induced autoimmunity targeted the liver. Compared to other tissues the liver has an unusually robust capacity for repair and regeneration. This investigation examined both time-dependent and dose-dependent effects of TCE on hepatoprotective and pro-inflammatory events in liver and macrophages from female MRL+/+mice. After a 12-week exposure to TCE in drinking water a dose-dependent decrease in macrophage production of IL-6 at both the transcriptional and protein level was observed. A longitudinal study similarly showed that TCE inhibited macrophage IL-6 production. In terms of the liver, TCE had little effect on expression of pro-inflammatory genes (Tnfa, Saa2 or Cscl1) until the end of the 40-week exposure. Instead, TCE suppressed hepatic expression of genes involved in IL-6 signaling (Il6r, gp130, and Egr1). Linear regression analysis confirmed liver histopathology in the TCE-treated mice correlated with decreased expression of Il6r. A toxicodynamic model was developed to estimate the effects of TCE on IL-6 signaling and liver pathology under different levels of exposure and rates of repair. This study underlined the importance of longitudinal studies in mechanistic evaluations of immuntoxicants. It showed that later-occurring liver pathology caused by TCE was associated with early suppression of hepatoprotection rather than an increase in conventional pro-inflammatory events. This information was used to create a novel toxicodynamic model of IL-6-mediated TCE-induced liver inflammation.

Is green tea a potential trigger for autoimmune hepatitis?

A case of autoimmune liver hepatitis is reported: the onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan. We hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives+irbesartan+green tea) that normally would not be able to cause damage. Her particular hepatic metabolism further increased the drugs' concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis.

Association of STAT4 polymorphisms with susceptibility to type-1 autoimmune hepatitis in the Japanese population

Background/Aims

Recent studies demonstrated an association of STAT4 polymorphisms with autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis, indicating multiple autoimmune diseases share common susceptibility genes. We therefore investigated the influence of STAT4 polymorphisms on the susceptibility and phenotype of type-1 autoimmune hepatitis in a Japanese National Hospital Organization (NHO) AIH multicenter cohort study.

Methodology/Principal Findings

Genomic DNA from 460 individuals of Japanese origin including 230 patients with type-1 autoimmune hepatitis and 230 healthy controls was analyzed for two single nucleotide polymorphisms in the STAT4 gene (rs7574865, rs7582694). The STAT4 rs7574865T allele conferred risk for type-1 autoimmune hepatitis (OR = 1.61, 95% CI = 1.23–2.11; P = 0.001), and patients without accompanying autoimmune diseases exhibited an association with the rs7574865T allele (OR = 1.50, 95%CI = 1.13–1.99; P = 0.005). Detailed genotype-phenotype analysis of type-1 autoimmune hepatitis patients with (n = 44) or without liver cirrhosis (n = 186) demonstrated that rs7574865 was not associated with the development of liver cirrhosis and phenotype (biochemical data and the presence of auto-antibodies).

Conclusions/Significance

This is the first study to show a positive association between a STAT4 polymorphism and type-1 autoimmune hepatitis, suggesting that autoimmune hepatitis shares a gene commonly associated with risk for other autoimmune diseases.

Autoimmune hepatitis in childhood: The role of genetic and immune factors

Autoimmune hepatitis (AIH) is a rare chronic inflammatory disease of the liver, which affects a group of patients who lost their immunological tolerance to antigens of the liver. It is clinically characterized by hypergammaglobulinemia, elevated liver enzymes, presence of autoantibodies and histological changes. Although being rare in children, it represents a serious cause of chronic hepatic disease that can lead to cirrhosis and hepatic failure. Clinical findings, exclusion of more common liver disorders and the detection of antibodies antinuclear antibodies, smooth muscle antibodies and anti-LKM1 are usually enough for diagnosis on clinical practice. The pathogenic mechanisms that lead to AIH remain obscure, but some research findings suggest the participation of immunologic and genetic factors. It is not yet knew the triggering factor or factors that stimulate inflammatory response. Several mechanisms proposed partially explain the immunologic findings of AIH. The knowledge of immune factors evolved might result in better markers of prognosis and response to treatment. In this review, we aim to evaluate the findings of research about genetic and immune markers and their perspectives of application in clinical practice especially in pediatric population.

Genetic association of interleukin-6 polymorphism (-174 G/C) with chronic liver diseases and hepatocellular carcinoma

Interleukin-6 (IL-6) is a pleiotropic cytokine which is expressed in many inflammatory cells in response to different types of stimuli, regulating a number of biological processes. The IL-6 gene is polymorphic in both the 5’ and 3’ flanking regions and more than 150 single nucleotide polymorphisms have been identified so far. Genetic polymorphisms of IL-6 may affect the outcomes of several diseases, where the presence of high levels of circulating IL-6 have been correlated to the stage and/or the progression of the disease itself. The -174 G/C polymorphism is a frequent polymorphism, that is located in the upstream regulatory region of the IL-6 gene and affects IL-6 production. However, the data in the literature on the genetic association between the -174 G/C polymorphism and some specific liver diseases characterized by different etiologies are still controversial. In particular, most of the studies are quite unanimous in describing a correlation between the presence of the high-producer genotype and a worse evolution of the chronic liver disease. This is valid for patients with hepatitis C virus (HCV)-related chronic hepatitis and liver cirrhosis and hepatocellular carcinoma (HCC) whatever the etiology. Studies in hepatitis B virus-related chronic liver diseases are not conclusive, while specific populations like non alcoholic fatty liver disease/non-alcoholic steatohepatitis, autoimmune and human immunodeficiency virus/HCV co-infected patients show a higher prevalence of the low-producer genotype, probably due to the complexity of these clinical pictures. In this direction, a systematic revision of these data should shed more light on the role of this polymorphism in chronic liver diseases and HCC.