Hepatic expression of tumor necrosis factor-α and evaluation of MAPK-p38 and NFκB signaling pathways in autoimmune hepatitis

OBJECTIVES

Autoimmune hepatitis (AIH) is a necroinflammatory disease that occurs when genetically susceptible individuals are exposed to an environmental trigger. It is a rare disease, and its epidemiological aspects are nearly unknown in Northeast Brazil. In the literature, the activation of components of the inflammatory cascade pathways, including interleukins such as TNF-α and signaling factors like MAPK-p38 and NFκB, in the pathogenesis of AIH is well described in animal models. This study evaluated, for the first time, the immunostaining of TNF-α, MAPK-p38, and NFκB in immunohistochemical analysis of liver biopsies from AIH patients. The activation of the MAPK-p38 pathway was also studied through immunoassay analysis in the peripheral blood of AIH patients.

METHODS AND RESULTS

Data from medical records of 25 AIH patients were analyzed. Histological and immunohistochemical analysis of liver tissue obtained from biopsies was performed to detect NFκB, MAPK-p38, and TNF-α. Immunoassay analysis of the MAPK-p38 pathway was performed in peripheral blood from 18 AIH patients and 8 healthy volunteers. Medical record analysis showed an average age of 33.3 years, with a female predominance in a ratio of 7.3:1. Concomitance with other autoimmune diseases was observed in 36 % of patients, with thyroid disorders being the most prominent among them, and an 8 % indication for liver transplantation. In the evaluation of autoantibodies, ANA was detected in 52 %, followed by SMA at 20 %, and Anti-LKM-1 at 16 %. Liver biopsy findings were like the global literature, with interface hepatitis and lymphoplasmacytic infiltration observed. Immunohistochemical analysis showed immunostaining for NFκB, MAPK-p38, and TNF-α, corroborating the inflammatory and immunological characteristics of the disease. Immunoassay analysis in peripheral blood confirmed the activation of the MAPK-p38 signaling pathway, with a statistically significant difference between AIH patients and healthy controls.

CONCLUSIONS

The epidemiological and histological findings of AIH in this study in Northeast Brazil were like global population data. Immunohistochemical analysis of liver tissue and immunoassay analysis in peripheral blood confirmed the activation of TNF-α and the NFκB and MAPK-p38 signaling pathways in AIH patients.

Complementary and alternative medicines and liver disease

Complementary and alternative medicines (CAM) include conventional medical treatments. Patients worldwide use CAM at alarming rates; thus, reports of CAM-related DILI have been on the rise. The clinical presentations include asymptomatic liver test abnormalities, acute hepatitis with or without jaundice, acute cholestatic liver disease (bland or with hepatitis), acute liver failure, severe hepatitis with features of portal hypertension, and acute decompensation of known or unknown cirrhosis that can lead to acute-on-chronic liver failure. Acute hepatitis with or without necrosis, hepatocellular and canalicular cholestasis, herb-induced or CAM-triggered autoimmune hepatitis, granulomatous hepatitis, severe steatohepatitis, and vanishing bile duct syndrome are common liver biopsy findings in CAM-DILI. The presence of preexisting liver disease predicts severe liver injury, risk of progression to liver failure, and decreased transplant-free survival in patients with CAM-DILI. This review discusses global epidemiology and trends in CAM-DILI, clinical presentation, assessment and outcomes, commonly emerging threats in the context of hepatotoxic herbs, pragmatic assessment of "liver beneficial" herbs and health care myths, patient communication, regulatory framework, and future directions on research in CAM.

The role of amino acid metabolism in autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory chronic liver disease with persistent and recurrent immune-mediated liver injury. The exact cause of AIH is still not fully understood, but it is believed to be primarily due to an abnormal activation of the immune system, leading to autoimmune injury caused by the breakdown of autoimmune tolerance. Although the pathogenesis of AIH remains unclear, recent studies have shown that abnormalities in amino acid metabolism play significant roles in its development. These abnormalities in amino acid metabolism can lead to remodeling of metabolic processes, activation of signaling pathways, and immune responses, which may present new opportunities for clinical intervention in AIH. In this paper, we first briefly outline the recent progress of clinically relevant research on AIH, focusing on the role of specific amino acid metabolism (including glutamine, cysteine, tryptophan, branched-chain amino acids, etc.) and their associated metabolites, as well as related pathways, in the development of AIH. Furthermore, we discuss the scientific issues that remain to be resolved regarding amino acid metabolism, AIH development and related clinical interventions, with the aim of contributing to the future development of amino acid metabolism-based as a new target for the clinical diagnosis and treatment of AIH.

Statins Are Associated With a Decreased Risk of Severe Liver Disease in Individuals With Noncirrhotic Chronic Liver Disease

BACKGROUND & AIMS

Little is known about the potential impact of statins on the progression of noncirrhotic chronic liver diseases (CLDs) to severe liver disease.

METHODS

Using liver histopathology data in a nationwide Swedish cohort, we identified 3862 noncirrhotic individuals with CLD and statin exposure, defined as a statin prescription filled for 30 or more cumulative defined daily doses. Statin users were matched to 3862 (statin) nonusers with CLD through direct 1:1 matching followed by propensity score matching. Cox regression was used to estimate hazard ratios (HRs) for the primary outcome of incident severe liver disease (a composite of cirrhosis, hepatocellular carcinoma, and liver transplantation/liver-related mortality).

RESULTS

A total of 45.3% of CLD patients had nonalcoholic fatty liver disease, 21.9% had alcohol-related liver disease, 17.7% had viral hepatitis, and 15.1% had autoimmune hepatitis. During follow-up evaluation, 234 (6.1%) statin users vs 276 (7.1%) nonusers developed severe liver disease. Statin use was associated with a decreased risk of developing severe liver disease (HR, 0.60; 95% CI, 0.48-0.74). Statistically significantly lower rates of severe liver disease were seen in alcohol-related liver disease (HR, 0.30; 95% CI, 0.19-0.49) and in nonalcoholic fatty liver disease (HR, 0.68; 95% CI, 0.45-1.00), but not in viral hepatitis (HR, 0.76; 95% CI, 0.51-1.14) or autoimmune hepatitis (HR, 0.88; 95% CI, 0.48-1.58). Statin use had a protective association in both prefibrosis and fibrosis stages at diagnosis. Statin use was associated with lower rates of progression to cirrhosis (HR, 0.62; 95% CI, 0.49-0.78), hepatocellular carcinoma (HR, 0.44; 95% CI, 0.27-0.71), and liver-related mortality (HR, 0.55; 95% CI, 0.36-0.82).

CONCLUSIONS

Among individuals with noncirrhotic CLD, incident statin use was linked to lower rates of severe liver disease, suggesting a potential disease-modifying role.

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.

Manganese Exacerbates ConA-Induced Liver Inflammation via the cGAS-STING Signaling Pathway

There is a potential association between the dysregulation of trace elements and impaired liver function. Elevated levels of manganese, an essential metal ion, have been observed in liver-related diseases, and excessive intake of manganese can worsen liver damage. However, the specific mechanisms underlying manganese-induced liver injury are not well understood. The aim of our study was to investigate the effects of excess manganese on autoimmune hepatitis (AIH) and elucidate its mechanisms. Our findings revealed that manganese exacerbates liver damage under ConA-induced inflammatory conditions. Transcriptomic and experimental data suggested that manganese enhances inflammatory signaling and contributes to the inflammatory microenvironment in the liver of AIH mice. Further investigations demonstrated that manganese exacerbates liver injury by activating the cGAS-STING signaling pathway and its downstream pro-inflammatory factors such as IFN[Formula: see text], IFN[Formula: see text], TNF[Formula: see text], and IL-6 in the liver of AIH mice. These results suggest that manganese overload promotes the progression of AIH by activating cGAS-STING-mediated inflammation, providing a new perspective for the treatment and prognosis of AIH.

Presence of ectopic germinal center structures in autoimmune hepatitis

Autoimmune tissues may contain ectopic germinal centers (EGCs). However, these structures have never been described in the liver of patients suffering from autoimmune hepatitis (AIH). We retrospectively reviewed histological features of 120 definite AIH cases, and found 10 cases harboring markers of EGCs. In these cases, CD21+ follicular dendritic cells were intermixed with CD3+ T and CD20+ B lymphocytes. The latter expressed the GC-specific marker bcl6, and some were proliferative as assessed by Ki67 expression. Antibody-secreting cells (ASCs) defined by expression of the mum-1 transcription factor and presence of cytoplasmic IgMs were usually present in the periphery of these structures, but some were also present within the EGCs. Notably, some ASCs were IgG-switched. Common treatment applied to AIH patients achieved biochemical normalization as efficiently as in patients without EGCs. In the present study, we provide the proof for the occurrence of functional EGCs enabling differentiation of B cells into ASCs and occurrence of immunoglobulin switch in AIH livers.

Engineering M2 type macrophage-derived exosomes for autoimmune hepatitis immunotherapy via loading siRIPK3

Autoimmune hepatitis (AIH) is a progressive liver disease mediated by the immune system that involves an imbalance in pro-inflammatory and regulatory mechanisms including regulatory T cells (Tregs), T helper 17 (Th17) cells, Th1, macrophages, and many other immune cells. Current steroid therapy for AIH has significant systemic side effects and is poorly tolerated by some individuals. Therefore, there is an urgent need for alternative treatments. Maintaining homeostasis in macrophage differentiation and activation is crucial for regulating immune responses in hepatitis. In this study, we loaded small interfering RNA (siRNA) targeting receptor-interacting protein kinase 3 (RIPK3) into M2-type macrophage-derived exosomes (M2 Exos) to create functionalized exosomes called M2 Exos/siRIPK3. These exosomes demonstrated a natural ability to target the liver in mice, as they were efficiently taken up by hepatic macrophages and showed significant and stable accumulation. M2 Exos/siRIPK3 effectively mitigated immune-mediated hepatitis by suppressing the expression of RIPK3, resulting in a reduced release of pro-inflammatory cytokines and chemokines in both liver tissues and serum. Additionally, M2 Exos/siRIPK3 exhibited immunomodulatory effects, as its administration resulted in a decreased proportion of hepatic and splenic Th17 cells, along with an increased ratio of Tregs. Overall, this study suggests that loading small molecule drugs onto M2 Exos could be a promising approach for developing immunomodulators that specifically target liver macrophages to treat AIH. This strategy has the potential to provide a safer and more effective alternative to current therapy for AIH patients.

Autoimmune Hepatitis: Pathophysiology

Genome-wide association analyses suggest that HLA genes including HLA-DRB*0301, HLA-DRB*0401, and HLA-B*3501 as well as non-HLA genes including CD28/CTLA4/ICOS and SYNPR increased AIH susceptibility. The destruction of hepatocytes is the result of the imbalance between proinflammatory cells and immunosuppressive cells, especially the imbalance between Tregs and Th17 cells. The microbiome in patients with AIH is decreased in diversity with a specific decline in Bifidobacterium and enrichment in Veillonella and Faecalibacterium. Recent evidence has demonstrated the pathogenic role of E. gallinarum and L.reuteri in inducing autoimmunity in the liver.

Nuezhenoside G13 from Osmanthus fragrans fruit ameliorates Concanavalin A-induced autoimmune hepatitis by regulating the NF-κB/MAPK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Osmanthus fragrans fruit (OFF) exhibits hepatoprotective function, and it is consumed as food and used in traditional medicine in China. Nuezhenoside G13 (G13) is present in the highest levels in OFF. Autoimmune hepatitis (AIH) is a manifestation of liver disease and seriously endangers health. However, it remains unclear whether G13 affects AIH.

AIM OF THE STUDY

To clarify the effect of G13 on AIH and its exact underlying mechanism from a new perspective.

MATERIALS AND METHODS

We used a Concanavalin A-induced AIH mouse model and lipopolysaccharide-treated Raw264.7 cells to quantify serum biochemical indicators and confirm whether G13 exhibited protective effects in the AIH mice. Furthermore, we evaluated the effect of G13 via hematoxylin and eosin and immunohistochemical staining. We used enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction to quantify the inflammatory factors. We confirmed that G13 inhibited apoptosis via terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Molecular docking, immunofluorescence, and western blotting experiments of G13 and key proteins of the NF-κB/MAPK pathway revealed that G13 alleviated inflammation. In addition, Cell Counting Kit-8, ELISA, NO detection, and western blotting assays were performed. Finally, we used an inhibitor of the p38 MAPK to verify that G13 reduced inflammation through the NF-κB/MAPK pathway in Raw264.7 cells.

RESULTS

The in vivo experiments revealed that G13 improved oxidative stress and apoptosis. In addition, G13 decreased the expression levels of CD4+, CD8+, F4/80+, and Ly6G and the secretion of inflammatory factors. Interestingly, G13 reduced the phosphorylation levels of IκBα, NF-κB, JNK, ERK1/2, and p38. Additionally, the in vitro experiments revealed that G13 alleviated inflammation through the NF-κB/MAPK pathway in lipopolysaccharide-treated Raw264.7 cells. Furthermore, molecular docking demonstrated that the binding fraction of G13 with these proteins was high.

CONCLUSION

G13 suppressed oxidative stress, apoptosis, and inflammation in a Concanavalin A-induced AIH mouse model. Furthermore, G13 exerted its effect through the NF-κB/MAPK pathway.

Immune responses and clinical outcomes after COVID-19 vaccination in patients with liver disease and liver transplant recipients

BACKGROUND & AIMS

Comparative assessments of immunogenicity following different COVID-19 vaccines in patients with distinct liver diseases are lacking. SARS-CoV-2-specific T-cell and antibody responses were evaluated longitudinally after one to three vaccine doses, with long-term follow-up for COVID-19-related clinical outcomes.

METHODS

A total of 849 participants (355 with cirrhosis, 74 with autoimmune hepatitis [AIH], 36 with vascular liver disease [VLD], 257 liver transplant recipients [LTRs] and 127 healthy controls [HCs]) were recruited from four countries. Standardised immune assays were performed pre and post three vaccine doses (V1-3).

RESULTS

In the total cohort, there were incremental increases in antibody titres after each vaccine dose (p <0.0001). Factors associated with reduced antibody responses were age and LT, whereas heterologous vaccination, prior COVID-19 and mRNA platforms were associated with greater responses. Although antibody titres decreased between post-V2 and pre-V3 (p = 0.012), patients with AIH, VLD, and cirrhosis had equivalent antibody responses to HCs post-V3. LTRs had lower and more heterogenous antibody titres than other groups, including post-V3 where 9% had no detectable antibodies; this was heavily influenced by intensity of immunosuppression. Vaccination increased T-cell IFNγ responses in all groups except LTRs. Patients with liver disease had lower functional antibody responses against nine Omicron subvariants and reduced T-cell responses to Omicron BA.1-specific peptides compared to wild-type. 122 cases of breakthrough COVID-19 were reported of which 5/122 (4%) were severe. Of the severe cases, 4/5 (80%) occurred in LTRs and 2/5 (40%) had no serological response post-V2.

CONCLUSION

After three COVID-19 vaccines, patients with liver disease generally develop robust antibody and T-cell responses to vaccination and have mild COVID-19. However, LTRs have sustained no/low antibody titres and appear most vulnerable to severe disease.

IMPACT AND IMPLICATIONS

Standardised assessments of the immune response to different COVID-19 vaccines in patients with liver disease are lacking. We performed antibody and T-cell assays at multiple timepoints following up to three vaccine doses in a large cohort of patients with a range of liver conditions. Overall, the three most widely available vaccine platforms were immunogenic and appeared to protect against severe breakthrough COVID-19. This will provide reassurance to patients with chronic liver disease who were deemed at high risk of severe COVID-19 during the pre-vaccination era, however, liver transplant recipients had the lowest antibody titres and remained vulnerable to severe breakthrough infection. We also characterise the immune response to multiple SARS-CoV-2 variants and describe the interaction between disease type, severity, and vaccine platform. These insights may prove useful in the event of future viral infections which also require rapid vaccine development and delivery to patients with liver disease.

Natural Killer T (NKT) Cells in Autoimmune Hepatitis: Current Evidence from Basic and Clinical Research

Natural killer T (NKT) cells are unconventional T cells that are activated by glycolipid antigens. They can produce a variety of inflammatory and regulatory cytokines and, therefore, modulate multiple aspects of the immune response in different pathological settings, including autoimmunity. NKT cells have also been implicated in the immunopathogenesis of autoimmune hepatitis, and in this review we summarize and analyze the main studies investigating the involvement and/or homeostasis of NKT cells in this disease. In detail, the evidence from both basic and clinical research has been specifically analyzed. Even though the experimental murine models supported a relevant role of NKT cells in immune-mediated hepatic injury, very few studies specifically investigated NKT cell homeostasis in patients with autoimmune hepatitis; however, these initial studies reported some alterations of NKT cells in these patients, which may also correlate with the disease activity to some extent. Further clinical studies are needed to investigate the potential role and use of NKT cell analysis as a disease marker of clinical relevance, and to better understand the precise cellular and molecular mechanisms by which NKT cells contribute to the pathogenesis of autoimmune hepatitis.

Pemetrexed ameliorates Con A-induced hepatic injury by restricting M1 macrophage activation

Autoimmune hepatitis (AIH), characterized by immune-driven liver destruction and cytokine production, is a progressive inflammatory liver condition that may progress to hepatic cirrhosis or tumors. However, the underlying mechanism is not well understood, and the treatment options for this disease are limited. Pemetrexed (PEM), a clinically used anti-folate drug for treating various tumors, was found to inhibit the nuclear factor (NF)-κB signaling pathways that exert an important role in the development of AIH. Here, we investigated the impact of PEM on immune-mediated hepatic injuries using a murine model of Concanavalin A (Con A)-induced hepatitis, a well-established model for AIH. Mice received intraperitoneal PEM injections 3 times at 12-hour intervals, and two hours later, they were challenged with Con A. Liver samples and serum were collected after 10 h. The results indicate that PEM significantly improved mouse survival rates and lowered serum transaminase levels. Moreover, PEM effectively alleviated oxidative stress, reduced histopathological liver damage, and mitigated hepatocyte apoptosis. Notably, it reduced the activation of M1-type macrophages in the liver. The expression of proinflammatory cytokines and genes associated with M1 macrophages, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-12, IL-1β, and inducible nitric oxide synthase (iNOS), was also decreased. Finally, the results indicated that PEM regulates M1 macrophage activation by modulating the NF-κB signaling pathways. Overall, these results demonstrate that PEM effectively guards against immune-mediated hepatic injuries induced by Con A by inhibiting M1 macrophage activation through the NF-κB signaling pathways and indicate the potential of PEM as a practical treatment option for AIH in clinical settings.

TPN10475 alleviates concanavalin A-induced autoimmune hepatitis by limiting T cell development and function through inhibition of PI3K-AKT pathway

Autoimmune hepatitis (AIH) is an inflammatory liver disease in which the autoimmune system instigates an attack on the liver, causing inflammation and liver injury, and its incidence has increased worldwide in recent years. The mouse model of acute hepatitis established by concanavalin A (Con A) is a typical and recognized mouse model for the study of T-cell-dependent liver injury. In this study, we aimed to investigate whether the artemisinin derivative TPN10475 could alleviate AIH and its possible mechanisms. TPN10475 effectively inhibited lymphocyte proliferation and IFN-γ+ T cells production in vitro, alleviated liver injury by decreasing infiltrating inflammatory T cells producing IFN-γ in the liver and peripheral immune tissues, and demonstrated that TPN10475 weakened the activation and function of T cells by inhibiting PI3K-AKT signaling pathway. These results suggested that TPN10475 may be a potential drug for the treatment of AIH, and the inhibition of PI3K-AKT signaling pathway may provide new ideas for the study of the pathogenesis of AIH.

Bile Acids in Autoimmune Liver Disease: Unveiling the Nexus of Inflammation, Inflammatory Cells, and Treatment Strategies

As bile acids not solely play an essential role in nutrition absorption, but also in regulating metabolic functions as well as immune response, bile acids and their signaling pathways are increasingly acknowledged as potential therapeutic targets in the context of chronic liver diseases. Bile acid receptors such as G protein bile acid-activated receptor 1 and farnesoid X receptor are expressed in different immune cells engaged in innate immunity. Recently, a series of studies have revealed distinct functions of bile acids and bile acid receptors within the adaptive immune system. In addition, a variety of molecules targeting bile acid receptors and transporters are currently in advanced stages of clinical development. Autoimmune liver diseases including conditions like primary biliary cholangitis, primary sclerosing cholangitis, and autoimmune hepatitis can lead to chronic inflammation, fibrosis, and even cirrhosis and liver failure. In this review, we focus on the role of bile acids in the inflammatory aspects of autoimmune liver diseases.

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

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

RAGE deficiency ameliorates autoimmune hepatitis involving inhibition of IL-6 production via suppressing protein Arid5a in mice

Activation of T cells and pro-inflammatory cytokines are essential for human autoimmune hepatitis. RAGE is one of the receptors for the inflammatory alarm molecule high mobility group box 1 (HMGB1), and it is involved in autoimmune hepatitis. However, the molecular mechanism of RAGE in the context of autoimmune hepatitis remains elusive. This study aimed to identify the function and mechanism of RAGE in autoimmune hepatitis. The role and underlying mechanisms of RAGE signaling-driven immune inflammatory response in ConA-induced experimental hepatitis were examined using the RAGE-deficient mice. We found that the RAGE deficiency protected the mouse from liver inflammatory injury caused by the ConA challenge. mRNA expression of VCAM-1, IL-6, and TNF-α within the livers is markedly decreased in RAGE-deficient mice compared to wild-type mice. In parallel, RAGE deficiency leads to reduced levels of the serum pro-inflammatory cytokines IL-6 and TNF-α as compared with wild-type control mice. RAGE-deficient mice exhibit increased hepatic NK cells and decreased CD4+ T cells compared with wild-type control mice. Notably, in vivo blockade of IL-6 in wild-type mice significantly protected mice from ConA-induced hepatic injury. Furthermore, RAGE deficiency impaired IL-6 production and was associated with decreased expression of Arid5a in liver tissues, a half-life IL-6 mRNA regulator. RAGE signaling is important in regulating the development of autoimmune hepatitis. Immune regulation of RAGE may represent a novel therapeutic strategy to prevent immune-mediated liver injury.

Autoantigen-selected B cells are bystanders in spontaneous T cell-driven experimental autoimmune hepatitis

Autoreactive B cells are considered pathogenic drivers in many autoimmune diseases; however, it is not clear whether autoimmune B cells are invariably pathogenic or whether they can also arise as bystanders of T cell-driven autoimmune pathology. Here, we studied the B cell response in an autoantigen- and CD4+ T cell-driven model of autoimmune hepatitis (AIH), the Alb-iGP_Smarta mouse in which expression of a viral model antigen (GP) in hepatocytes and its recognition by GP-specific CD4+ T cells causes spontaneous AIH-like disease. T cell-driven AIH in Alb-iGP_Smarta mice was marked by autoantibodies and hepatic infiltration of plasma cells and B cells, particularly of isotype-switched memory B cells, indicating antigen-driven selection and activation. Immunosequencing of B cell receptor repertoires confirmed B cell expansion selectively in the liver, which was most likely driven by the hepatic GP model antigen, as indicated by branched networks of connected sequences and elevated levels of IgG antibodies to GP. However, intrahepatic B cells did not produce increased levels of cytokines and their depletion with anti-CD20 antibody did not alter the CD4+ T cell response in Alb-iGP_Smarta mice. Moreover, B cell depletion did not prevent spontaneous liver inflammation and AIH-like disease in Alb-iGP_Smarta mice. In conclusion, selection and isotype-switch of liver-infiltrating B cells was dependent on the presence of CD4+ T cells recognizing liver antigen. However, recognition of hepatic antigen by CD4+ T cells and CD4+ T cell-mediated hepatitis was not dependent on B cells. Thus, autoreactive B cells can be bystanders and need not be drivers of liver inflammation in AIH.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Morphologic and molecular analysis of liver injury after SARS-CoV-2 vaccination reveals distinct characteristics

BACKGROUND & AIMS

Liver injury after COVID-19 vaccination is very rare and shows clinical and histomorphological similarities with autoimmune hepatitis (AIH). Little is known about the pathophysiology of COVID-19 vaccine-induced liver injury (VILI) and its relationship to AIH. Therefore, we compared VILI with AIH.

METHODS

Formalin-fixed and paraffin-embedded liver biopsy samples from patients with VILI (n = 6) and from patients with an initial diagnosis of AIH (n = 9) were included. Both cohorts were compared by histomorphological evaluation, whole-transcriptome and spatial transcriptome sequencing, multiplex immunofluorescence, and immune repertoire sequencing.

RESULTS

Histomorphology was similar in both cohorts but showed more pronounced centrilobular necrosis in VILI. Gene expression profiling showed that mitochondrial metabolism and oxidative stress-related pathways were more and interferon response pathways were less enriched in VILI. Multiplex analysis revealed that inflammation in VILI was dominated by CD8+ effector T cells, similar to drug-induced autoimmune-like hepatitis. In contrast, AIH showed a dominance of CD4+ effector T cells and CD79a+ B and plasma cells. T-cell receptor (TCR) and B-cell receptor sequencing showed that T and B cell clones were more dominant in VILI than in AIH. In addition, many T cell clones detected in the liver were also found in the blood. Interestingly, analysis of TCR beta chain and Ig heavy chain variable-joining gene usage further showed that TRBV6-1, TRBV5-1, TRBV7-6, and IgHV1-24 genes are used differently in VILI than in AIH.

CONCLUSIONS

Our analyses support that SARS-CoV-2 VILI is related to AIH but also shows distinct differences from AIH in histomorphology, pathway activation, cellular immune infiltrates, and TCR usage. Therefore, VILI may be a separate entity, which is distinct from AIH and more closely related to drug-induced autoimmune-like hepatitis.

IMPACT AND IMPLICATIONS

Little is known about the pathophysiology of COVID-19 vaccine-induced liver injury (VILI). Our analysis shows that COVID-19 VILI shares some similarities with autoimmune hepatitis, but also has distinct differences such as increased activation of metabolic pathways, a more prominent CD8+ T cell infiltrate, and an oligoclonal T and B cell response. Our findings suggest that VILI is a distinct disease entity. Therefore, there is a good chance that many patients with COVID-19 VILI will recover completely and will not develop long-term autoimmune hepatitis.

The proportion of regulatory T cells in peripheral blood of patients with autoimmune hepatitis: A systematic review and meta-analysis

BACKGROUND

Many researches have reported the impairment of regulatory T cells (Tregs) in autoimmune hepatitis (AIH), whilst the change of Tregs in peripheral blood remains controversial. We performed this systematic review and meta-analysis to clarify the numerical change of circulating Tregs in AIH patients compared with healthy individuals.

METHODS

Relevant studies were identified from Medline, PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure, and WanFang Data. Twenty-nine studies involving 968 AIH patients and 583 healthy controls were included. Subgroup analysis stratified by Treg definition or ethnicity was performed, and analysis of active-phase AIH was conducted.

RESULTS

The proportions of Tregs among CD4 T cells and PBMCs were generally decreased in AIH patients compared with healthy controls. Subgroup analysis showed that circulating Tregs identified by CD4+CD25+/high, CD4+CD25+Foxp3+, CD4+CD25+/highCD127-/low, and Tregs in Asian population were decreased among CD4 T cells in AIH patients. No significant change of CD4+CD25+/highFoxp3+CD127-/low Tregs and Tregs in Caucasian population among CD4 T cells were found in AIH patients, whereas the number of studies was limited in these subgroups. Moreover, analysis of the active-phase AIH patients showed that Treg proportions were decreased generally, whereas no significant differences in Tregs/CD4 T cells were observed when markers CD4+CD25+Foxp3+, CD4+CD25+/highFoxp3+CD127-/low were used or in Caucasian population.

CONCLUSIONS

The proportions of Tregs among CD4 T cells and PBMCs were decreased in AIH patients compared with healthy controls generally, whereas Treg definition markers, ethnicity, and disease activity had influence on the results. Further large-scale and rigorous study is warranted.

COVID-19 and Liver Disease: An Evolving Landscape

The COVID-19 pandemic has resulted in significant worldwide morbidity and mortality. In this review, we examine the intricate relationships between COVID-19 and liver diseases. While respiratory manifestations of COVID-19 are well known, its impact and consequences in patients with liver diseases remain an area of ongoing investigation. COVID-19 can induce liver injury through various mechanisms and is associated with higher mortality in individuals with preexisting chronic liver disease. Mortality increases with the severity of chronic liver disease and the level of care required. The outcomes in patients with autoimmune hepatitis remain unclear, whereas liver transplant recipients are more likely to experience symptomatic COVID-19 but have comparable outcomes to the general population. Despite suboptimal immunological response, COVID-19 vaccinations are safe and effective in liver disease, although cases of autoimmune hepatitis-like syndrome have been reported. In conclusion, COVID-19 has significant implications in liver diseases; early recognition and treatments are important for improving patient outcomes.

Combined Salivary Proteome Profiling and Machine Learning Analysis Provides Insight into Molecular Signature for Autoimmune Liver Diseases Classification

Autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) are autoimmune liver diseases that target the liver and have a wide spectrum of presentation. A global overview of quantitative variations on the salivary proteome in presence of these two pathologies is investigated in this study. The acid-insoluble salivary fraction of AIH and PBC patients, and healthy controls (HCs), was analyzed using a gel-based bottom-up proteomic approach combined with a robust machine learning statistical analysis of the dataset. The abundance of Arginase, Junction plakoglobin, Desmoplakin, Hexokinase-3 and Desmocollin-1 decreased, while that of BPI fold-containing family A member 2 increased in AIHp compared to HCs; the abundance of Gelsolin, CD14, Tumor-associated calcium signal transducer 2, Clusterin, Heterogeneous nuclear ribonucleoproteins A2/B1, Cofilin-1 and BPI fold-containing family B member 2 increased in PBCp compared to HCs. The abundance of Hornerin decreased in both AIHp and PBCp with respect to HCs and provided an area under the ROC curve of 0.939. Machine learning analysis confirmed the feasibility of the salivary proteome to discriminate groups of subjects based on AIH or PBC occurrence as previously suggested by our group. The topology-based functional enrichment analysis performed on these potential salivary biomarkers highlights an enrichment of terms mostly related to the immune system, but also with a strong involvement in liver fibrosis process and with antimicrobial activity.

Immunomodulatory Effects of Microbiota-Derived Short-Chain Fatty Acids in Autoimmune Liver Diseases

Nonpathogenic commensal microbiota and their metabolites and components are essential to maintain a tolerogenic environment and promote beneficial health effects. The metabolic environment critically impacts the outcome of immune responses and likely impacts autoimmune and allergic responses. Short-chain fatty acids (SCFAs) are the main metabolites produced by microbial fermentation in the gut. Given the high concentration of SCFAs in the gut and portal vein and their broad immune regulatory functions, SCFAs significantly influence immune tolerance and gut-liver immunity. Alterations of SCFA-producing bacteria and SCFAs have been identified in a multitude of inflammatory diseases. These data have particular significance in primary biliary cholangitis, primary sclerosing cholangitis, and autoimmune hepatitis because of the close proximity of the liver to the gut. In this focused review, we provide an update on the immunologic consequences of SCFA-producing microbiota and in particular on three dominant SCFAs in autoimmune liver diseases.

HERV1-env Induces Unfolded Protein Response Activation in Autoimmune Liver Disease: A Potential Mechanism for Regulatory T Cell Dysfunction

Regulatory T cells (Tregs) are not terminally differentiated but can acquire effector properties. Here we report an increased expression of human endogenous retrovirus 1 (HERV1-env) proteins in Tregs of patients with de novo autoimmune hepatitis and autoimmune hepatitis, which induces endoplasmic reticulum (ER) stress. HERV1-env-triggered ER stress activates all three branches (IRE1, ATF6, and PERK) of the unfolded protein response (UPR). Our coimmunoprecipitation studies show an interaction between HERV1-env proteins and the ATF6 branch of the UPR. The activated form of ATF6α activates the expression of RORC and STAT3 by binding to promoter sequences and induces IL-17A production. Silencing of HERV1-env results in recovery of Treg suppressive function. These findings identify ER stress and UPR activation as key factors driving Treg plasticity (species: human).

Inflammasome and pyroptosis in autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and IgG4-related sclerosing cholangitis (IgG4-SC) are the four main forms of autoimmune liver diseases (AILDs), which are all defined by an aberrant immune system attack on the liver. Most previous studies have shown that apoptosis and necrosis are the two major modes of hepatocyte death in AILDs. Recent studies have reported that inflammasome-mediated pyroptosis is critical for the inflammatory response and severity of liver injury in AILDs. This review summarizes our present understanding of inflammasome activation and function, as well as the connections among inflammasomes, pyroptosis, and AILDs, thus highlighting the shared features across the four disease models and gaps in our knowledge. In addition, we summarize the correlation among NLRP3 inflammasome activation in the liver-gut axis, liver injury, and intestinal barrier disruption in PBC and PSC. We summarize the differences in microbial and metabolic characteristics between PSC and IgG4-SC, and highlight the uniqueness of IgG4-SC. We explore the different roles of NLRP3 in acute and chronic cholestatic liver injury, as well as the complex and controversial crosstalk between various types of cell death in AILDs. We also discuss the most up-to-date developments in inflammasome- and pyroptosis-targeted medicines for autoimmune liver disorders.

MAdCAM-1 does not play a central role in the early pathophysiology of autoimmune hepatitis

INTRODUCTION

CD4+ T cells are thought to have a central role in the pathogenesis of autoimmune hepatitis (AIH). Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) directs homing of CD4+ T cells in the alimentary tract and is a therapeutic target in inflammatory bowel diseases. Here we assessed MAdCAM-1 expression in AIH and viral hepatitis and related its expression with immune infiltrate analysis and histopathological key features.

METHODS

Hepatic portal areas of pretreatment biopsies (n=10) and follow-up biopsies (n=9) of patients with a confirmed diagnosis of AIH were assessed for MAdCAM-1 expression and infiltrate composition using immunohistochemistry and multispectral imaging (Vectra® Polaris™). Controls consisted of biopsies of patients with untreated chronic viral hepatitis B or C (n=22).

RESULTS

MAdCAM-1 expression on endothelium was sparsely present in portal fields of two treatment-naïve AIH patients. Three patients showed MAdCAM-1 expression within lymphoid aggregates. No expression of significance (including single-cell expression) was observed in the remaining 6 patients. In contrast, viral hepatitis C biopsies showed endothelial MAdCAM-1 expression in 8 of 13 untreated patients. Densities of both B-cells (CD20+) and CD4+ T-cells (CD3+ CD8-) were increased in AIH and viral hepatitis patients with MAdCAM-1 expression.

CONCLUSION

MAdCAM-1 was detected in liver biopsies in a minority of patients with AIH at the time of diagnosis suggesting no central role in its pathophysiology. Lymphoid or reticular MAdCAM-1 pattern expression was associated with more dense infiltrates of both B-cells and CD4⁺ T-cells, and may be related to the formation of secondary lymphoid follicles.

The imbalance of liver resident macrophages polarization promotes chronic autoimmune hepatitis development in mice

Background

Autoimmune hepatitis (AIH) is a chronic immune-mediated inflammatory liver disease. At present, it is largely unknown how the innate immune cells influence AIH development.

Objective

To inquiry about mechanism of liver resident macrophages in AIH development, thus offering a new direction for AIH targeted treatment.

Methods

The liver resident macrophages were eliminated by clodronate liposomes in AIH liver tissues, followed by HE and Picrosirius assay to detect liver fibrosis and lymphocyte infiltration. The liver resident macrophages polarization was detected by Immunohistochemistry and qPCR. The collagenase digestion was used to isolate Kupffer cells from AIH mice liver tissues and pro-/anti-inflammatory cytokines were determined by qPCR.

Results

M2 macrophages were the dominant phenotype at early immune response stage and hepatic inflammation was progressively aggravated after depletion of liver resident macrophages. M2 macrophages could effectively delay the development of AIH and could be polarized to M1 macrophages at the disease progresses. TLR2 ligands could promote M2 macrophages producing anti-inflammatory cytokines, whereas TLR4 ligands could promote M1 macrophages producing proinflammatory cytokines. The change of TLR2 and TLR4 ligands could lead to continuous high expression of TLR4 and decreased expression of TLR2 in macrophages to further affect liver resident macrophages polarization state.

Conclusion

TLR2 and TLR4 ligands mediated liver resident macrophages polarization to favor chronic autoimmune hepatitis development.

Suppression of YTHDF2 attenuates autoimmune hepatitis by expansion of myeloid-derived suppressor cells

BACKGROUND & AIMS

The N6-methyladenosine (m⁶A) reader YTH domain-containing family protein 2 (YTHDF2) is critically involved in a multiplicity of biological processes by mediating the degradation of m⁶A modified mRNAs. Based on our current understanding of this process, we hypothesized that YTHDF2 will play a role in the natural history and function of myeloid-derived suppressor cells (MDSC) and in particular in AIH.

APPROACH & RESULTS

We took advantage of YTHDF2 conditional knock-out mice to first address the phenotype and function of MDSCs by flow cytometry. Importantly, the loss of YTHDF2 resulted in a gradual elevation of MDSCs including PMN-MDSCs both in liver and ultimately in the BM. Notably, YTHDF2 deficiency in myeloid cells attenuated concanavalin (ConA)-induced liver injury, with enhanced expansion and chemotaxis to liver. Furthermore, MDSCs from Ythdf2^CKO mice had a greater suppressive ability to inhibit the proliferation of T cells. Using multi-omic analysis of m⁶A RNA immunoprecipitation (RIP) and mRNA sequencing, we noted RXRα as potential target of YTHDF2. Indeed YTHDF2-RIP-qPCR confirmed that YTHDF2 directly binds RXRα mRNA thus promoting degradation and decreasing gene expression. Finally, by IHC and immunofluorescence, YTHDF2 expression was significantly upregulated in the liver of patients with AIH which correlated with the degree of inflammation.

CONCLUSION

Suppression of YTHDF2 enhances the expansion, chemotaxis and suppressive function of MDSCs and our data reveals a unique therapeutical target in immune mediated hepatitis.

Serum metabolic profiling of targeted bile acids reveals potentially novel biomarkers for primary biliary cholangitis and autoimmune hepatitis

BACKGROUND

Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) are two unexplained immune diseases. The golden standard for diagnosis of these diseases requires a liver biopsy. Liver biopsy is not widely accepted by patients because of its invasive nature, and atypical liver histology can confuse diagnosis. In view of the lack of effective diagnostic markers for PBC and AIH, combined with the increasingly mature metabolomics technologies, including full-contour metabolomics and target.

AIM

To determine non-invasive, reliable, and sensitive biochemical markers for the differential diagnosis of PBC and AIH.

METHODS

Serum samples from 54 patients with PBC, 26 patients with AIH and 30 healthy controls were analyzed by Ultra-high performance liquid chromatography-tandem mass spectrometry serum metabolomics. The metabolites and metabolic pathways were identified, and the metabolic changes, metabolic pathways and inter-group differences between PBC and AIH were analyzed. Fifteen kinds of target metabolites of bile acids (BAs) were quantitatively analyzed by SRM, and the differential metabolites related to the diagnosis of PBC were screened by receiver operating characteristic curve analysis.

RESULTS

We found the changes in the levels of amino acids, BAs, organic acids, phospholipids, choline, sugar, and sugar alcohols in patients with PBC and AIH. Furthermore, the SRM assay of BAs revealed the increased levels of chenodeoxycholic acid, lithocholic acid (LCA), taurolithocholic acid (TLCA), and LCA + TLCA in the PBC group compared with those in the AIH group. The levels of BAs may be used as biomarkers to differentiate PBC from AIH diseases. The levels of glycochenodeoxycholic acid, glycochenodeoxycholic sulfate, and taurodeoxycholic acid were gradually elevated with the increase of Child-Pugh class, which was correlated with the severity of disease.

CONCLUSION

The results demonstrated that the levels of BAs could serve as potential biomarkers for the early diagnosis and assessment of the severity of PBC and AIH.

TOX deficiency facilitates the differentiation of IL-17A-producing γδ T cells to drive autoimmune hepatitis

The specification of the αβ/γδ lineage and the maturation of medullary thymic epithelial cells (mTECs) coordinate central tolerance to self-antigens. However, the mechanisms underlying this biological process remain poorly clarified. Here, we report that dual-stage loss of TOX in thymocytes hierarchically impaired mTEC maturation, promoted thymic IL-17A-producing γδ T-cell (Tγδ17) lineage commitment, and led to the development of fatal autoimmune hepatitis (AIH) via different mechanisms. Transfer of γδ T cells from TOX-deficient mice reproduced AIH. TOX interacted with and stabilized the TCF1 protein to maintain the balance of γδ T-cell development in thymic progenitors, and overexpression of TCF1 normalized αβ/γδ lineage specification and activation. In addition, TOX expression was downregulated in γδ T cells from AIH patients and was inversely correlated with the AIH diagnostic score. Our findings suggest multifaceted roles of TOX in autoimmune control involving mTEC and Tγδ17 development and provide a potential diagnostic marker for AIH.

Intrahepatic activated leukocyte cell adhesion molecule induces CD6highCD4+ T cell infiltration in autoimmune hepatitis

Background and objectives

Autoimmune hepatitis (AIH) is characterized by the expansion and accumulation of pathogenic T cells in liver. Although CD6 and its ligand activated leukocyte cell adhesion molecule (ALCAM) are involved in the evolution of multiple inflammatory diseases, their roles in the pathogenesis of AIH remain unknown. Herein, we aimed to investigate ALCAM-CD6 axis in AIH development.

Methods

Immunohistochemistry was performed to examine hepatic expression of CD6 and ALCAM. The concentration of serum ALCAM was evaluated by ELISA. The phenotypes of liver infiltrating T cells were determined by flow cytometry. Primary human CD4⁺ T cells were used for functional studies.

Results

Our data showed that patients with AIH exhibited significantly higher expression of CD6 in the liver as compared to primary biliary cholangitis (PBC), chronic hepatitis B (CHB), non-alcoholic liver disease (NAFLD), and healthy controls (HC). In addition, hepatic CD6 expression was strongly correlated with disease severity of AIH. CD6 was mainly expressed on CD4⁺ T cells in the liver and intrahepatic CD6^highCD4⁺ T cells demonstrated stronger proinflammatory response and proliferation features than CD6^low counterparts in both AIH and HC. ALCAM, the ligand of CD6, was highly expressed in the hepatocytes of AIH and serum ALCAM was strongly associated with clinical indices of AIH. Interestingly, close spatial location between CD6⁺CD4⁺ T cells and ALCAM⁺ hepatocytes was observed. Finally, we found that CD6^highCD4⁺ T cells showed enhanced capacity of trans-endothelial migration in vitro, which could be promoted by recombinant ALCAM.

Conclusions

Our study found that ALCAM-CD6 axis was upregulated in the AIH liver, suggesting a potential target for alleviating AIH.

SARS-CoV-2 Vaccine Response in Patients With Autoimmune Hepatitis

Patients suffering from autoimmune hepatitis, a chronic immune-mediated liver disease with an incidence of 0.9 to 2 per 100,000 population per year in Europe, are considered to have a particularly increased risk for coronavirus disease 2019 (Covid-19)-associated hospitalization and death.1,2 Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) vaccination provides an essential tool to reduce morbidity and mortality in this cohort. However, a large multicenter study in China has shown a lower immunogenic response to inactivated whole-virion SARS-CoV-2 vaccines of chronic liver disease patients in comparison with the healthy population.3 Furthermore, reports from inflammatory bowel diseases or rheumatic disorders showed a reduced serologic response in patients taking glucocorticoids or thiopurine.4,5 The decrease in vaccine-induced antibodies over time, as well as the emergence of variants of concern, led to the recommendation of an additional vaccination in immunocompromised patients.

[Predictors of hepatic encephalopathy in patients with severe acute liver injury]

INTRODUCTION

severe acute liver injury (SALI) formerly known as severe acute hepatitis is an acute inflammation of the liver with markers of liver injury (elevated transaminases) and signs of hepatocellular failure (jaundice and INR greater than 1.5) according to the latest definition of the European Association for the Study of the Liver (EASL). An important prognostic factor in SALI is the development of hepatic encephalopathy (HE) and thus its progression to acute liver failure (ALF), formerly known as acute severe hepatitis. The purpose of this study is to investigate factors predicting the development of hepatic encephalopathy during SALI.

METHODS

we conducted a retrospective study of patients treated for SALI between January 2000 and December 2019. We divided patients into two groups depending on whether hepatic encephalopathy occurred. We performed an analytical study comparing the two groups according to their epidemiological, biological and evolutionary data.

RESULTS

data from the medical records of fifty-nine patients were collected. A virus was the most frequent cause (63%). Hepatic encephalopathy occurred in 15 patients (25.4%). Factors predicting the development of HE in univariate analysis were a delay in consultation of more than 9 days, an INR level of more than 2.45, a bilirubin level of more than 230 μmol/l, creatinine greater than 60.5 μmol/l, urea greater than 5.5 mmol/l and MELD score greater than 26.5 (p=0.023, p=0.017, p=0.0001, p=0.049, p=0.0001, p=0.0001 respectively). Autoimmune hepatitis and an undetermined cause were associated with the development of HE (p=0,003 and p=0,044, respectively). In multivariate analysis, autoimmune aetiology and a urea level above 5.5 mmol/l were significantly associated with the occurrence of HE. No statistically significant differences were found between the two groups with regard to age, sex and diabetes.

CONCLUSION

SALI is a rare disease, mainly due to a virus in our country. Predictive factors of HE are important for early identification of patients at risk of adverse outcomes.

Epigenetic Aspects and Prospects in Autoimmune Hepatitis

The observed risk of autoimmune hepatitis exceeds its genetic risk, and epigenetic factors that alter gene expression without changing nucleotide sequence may help explain the disparity. Key objectives of this review are to describe the epigenetic modifications that affect gene expression, discuss how they can affect autoimmune hepatitis, and indicate prospects for improved management. Multiple hypo-methylated genes have been described in the CD4⁺ and CD19⁺ T lymphocytes of patients with autoimmune hepatitis, and the circulating micro-ribonucleic acids, miR-21 and miR-122, have correlated with laboratory and histological features of liver inflammation. Both epigenetic agents have also correlated inversely with the stage of liver fibrosis. The reduced hepatic concentration of miR-122 in cirrhosis suggests that its deficiency may de-repress the pro-fibrotic prolyl-4-hydroxylase subunit alpha-1 gene. Conversely, miR-155 is over-expressed in the liver tissue of patients with autoimmune hepatitis, and it may signify active immune-mediated liver injury. Different epigenetic findings have been described in diverse autoimmune and non-autoimmune liver diseases, and these changes may have disease-specificity. They may also be responses to environmental cues or heritable adaptations that distinguish the diseases. Advances in epigenetic editing and methods for blocking micro-ribonucleic acids have improved opportunities to prove causality and develop site-specific, therapeutic interventions. In conclusion, the role of epigenetics in affecting the risk, clinical phenotype, and outcome of autoimmune hepatitis is under-evaluated. Full definition of the epigenome of autoimmune hepatitis promises to enhance understanding of pathogenic mechanisms and satisfy the unmet clinical need to improve therapy for refractory disease.

Clinical update on risks and efficacy of anti-SARS-CoV-2 vaccines in patients with autoimmune hepatitis and summary of reports on post-vaccination liver injury

Patients with liver diseases, especially those with cirrhosis, have an increased mortality risk when infected by SARS-CoV-2 and therefore anti-SARS-CoV-2 vaccine has been recommended by leading Scientific Associations for all patients with chronic liver diseases. However, previous reports have shown a reduced antibody response following the full course of vaccination in immunosuppressed patients, including liver transplant recipients and several rheumatic diseases. This document, drafted by an expert panel of hepatologists appointed by the Italian Association for the Study of the Liver (AISF), aims to present the updated scientific data on the safety and efficacy of anti-SARS-CoV-2 mRNA vaccines in patients with autoimmune hepatitis (AIH). Furthermore, given the recent reports of sporadic cases of AIH-like cases following anti-SARS-CoV-2 mRNA vaccines, we summarize available data. Finally, we provide experts recommendations based on the limited data available.

Growth differentiation factor 15 as a novel diagnostic and therapeutic marker for autoimmune hepatitis

Growth differentiation factor 15 (GDF15) has been reported to be associated with fibrosis and cancer in liver disease. Diagnosis of autoimmune hepatitis (AIH) is often difficult because of the lack of specific markers. We investigated whether GDF15 is useful for diagnosing AIH and determined its therapeutic effects. We enrolled 171 Japanese patients as follows: AIH (n = 45), hepatitis B (HB) (n = 17), hepatitis C (HC) (n = 15), primary biliary cholangitis (PBC) (n = 20), and 74 healthy controls. Serum GDF15 levels were measured, and immunohistological analyses of GDF15 were performed using liver tissue of AIH patients. (1) GDF15 levels (pg/ml) were higher in AIH (1994.3 ± 1258.0) and HC (1568.0 ± 822.3) than in HB (953.2 ± 871.4), PBC (643.9 ± 247.0), and controls (475.3 ± 145.3) (p < 0.0001), as well as in cirrhosis patients (n = 31) than in non-cirrhosis patients (n = 66) (1926.6 ± 1026.0 vs. 1249.1 ± 1124.1, p < 0.0001). In non-cirrhosis patients, GDF15 levels were higher in AIH (1914.0 ± 1327.2) than in HC (955.7 ± 502.7), HB (519.3 ± 197.5), and PBC (643.9 ± 247.0) (p < 0.0001). (2) GDF15 was positively correlated with M2BPGi (r = 0.7728), total bilirubin (r = 0.6231), and PT-INR (r = 0.6332). (3) GDF15 levels could be used to distinguish AIH from other liver diseases in non-cirrhosis patients, with an area under the curve of 0.9373 (sensitivity 93.6%, specificity 79.3%, cut-off value 931.3). (4) GDF15 in AIH decreased after treatment. (5) Immunohistological analyses in AIH liver tissues revealed that GDF15 was strongly expressed in inflammatory cells, hepatic cytoplasm, and sinusoidal endothelial cells, but decreased after treatment. GDF15 is a novel diagnostic marker for AIH and is also expected to be a therapeutic marker for AIH.Clinical Trials Registration: The study protocol was approved by the institutional review board of Kurume University (Approval No.: 19049).

Concentration of Serum Matrix Metalloproteinase-3 in Patients With Primary Biliary Cholangitis

Background and Aims

Metalloproteinases (MMPs) are involved in many distinct processes in the liver. Matrix metalloproteinase-3 (MMP-3) plays an important role in connective tissue remodeling, degradation of collagen (types II, III, IV, IX, and X), proteoglycans, fibronectin, laminin, and elastin. In addition, MMP-3 can also activate other MMPs such as MMP-1, MMP-7, and MMP-9. Primary biliary cholangitis (PBC) is a cholestatic, autoimmune liver disease, characterized by the progressive destruction of intrahepatic bile ducts, leading to cholestasis, fibrosis, cirrhosis, and liver failure. Fibrosis is the result of an imbalance between production and degradation of the extracellular matrix surrounding hepatocytes. Our aim in the present study was to determine whether the measurement of serum MMP-3 is clinically useful for assessing ongoing liver fibrosis in patients with PBC.

Methods

The MMP-3 concentration was determined in 182 PBC patients and 80 non-PBC controls using a commercially available ELISA kit.

Results

Higher concentrations of MMP-3 were found in 61% of PBC patients. PBC subjects had greater MMP-3 levels than controls: 68.9 ± 62.6 vs 21.3 ± 7.4 ng/mL, p &lt; 0.001 for healthy subjects; 68.9 ± 62.6 vs 22.7 ± 7.6 ng/mL, p = 0.022 for autoimmune hepatitis controls; and 68.9 ± 62.6 vs 37.2 ± 17.4 ng/mL, p = 0.002 for primary sclerosing cholangitis controls. The serum MMP-3 concentration was significantly elevated in patients with higher bilirubin concentration (107.6 ± 85.8 vs 61.6 ± 46.1 ng/mL, p &lt; 0.001) and was correlated with the level of antimitochondrial antibodies specific for PBC. The concentration of MMP-3 in sera of PBC patients was also found to correlate with the state of liver fibrosis (OR = 4.3; p &lt; 0.01).

Conclusions

Our study demonstrated significantly higher MMP-3 levels in PBC patients than in healthy and pathological controls. Increased MMP-3 concentrations were positively correlated with various clinical and immunological parameters, and advanced liver fibrosis. The level of MMP-3 was associated with hepatic dysfunction and could play a role in the pathophysiology of hepatic fibrosis in PBC.