Protective effect of quercetin against macrophage-mediated hepatocyte injury via anti-inflammation, anti-apoptosis and inhibition of ferroptosis.

Yinchenhao Decoction (YCHD) is a classic prescription in traditional Chinese medicine (TCM). It appears to play an important role in anti-inflammation and autoimmunity protection. As one of the key active ingredients in YCHD, quercetin is a novel anti-inflammatory metabolite that exerts protective effects in many autoimmune diseases. However, its role in autoimmune hepatitis (AIH)-related hepatic injury has not been studied. The aim of this study was to reveal the hepatocyte protective mechanism of quercetin. In this study, we used Concanavalin A (Con A) to establish an in vitro hepatocyte injury-associated AIH model. Brl3a hepatocyte injury was induced by the supernatant of J774A.1 cells treated with Con A. We found that quercetin mitigated Con A-induced via macrophage-mediated Brl3a hepatocyte injury. Quercetin administration reduced the levels of alanine transaminase (ALT) and aspartate transaminase (AST) in the supernatant of Con A-treated Brl3a cells and attenuated the infiltration of J774A.1 macrophages induced by Con A. Moreover, quercetin effectively inhibited the expression of proinflammatory cytokines including interleukin-1ß (IL-1ß) by Con A. Furthermore, quercetin decreased hepatocyte apoptosis and ferroptosis levels in the macrophage-induced hepatocyte injury model. In conclusion, our study indicates that quercetin alleviates macrophage-induced hepatocyte damage by reducing the inflammatory response, apoptosis and ferroptosis. Our work suggests that quercetin might be a potential therapeutic strategy for AIH.

Berberine alleviates concanavalin A-induced autoimmune hepatitis in mice by modulating the gut microbiota.

BACKGROUND: Autoimmune hepatitis (AIH) is an immune-mediated liver disease of unknown etiology accompanied by intestinal dysbiosis and a damaged intestinal barrier. Berberine (BBR) is a traditional antibacterial medicine that has a variety of pharmacological properties. It has been reported that BBR alleviates AIH, but relevant mechanisms remain to be fully explored. METHODS: BBR was orally administered at doses of 100 mg⋅kg-1⋅d-1 for 7 days to mice before concanavalin A-induced AIH model establishment. Histopathological, immunohistochemical, immunofluorescence, western blotting, ELISA, 16S rRNA analysis, flow cytometry, real-time quantitative PCR, and fecal microbiota transplantation studies were performed to ascertain BBR effects and mechanisms in AIH mice. RESULTS: We found that liver necrosis and apoptosis were decreased upon BBR administration; the levels of serum transaminase, serum lipopolysaccharide, liver proinflammatory factors TNF-α, interferon-γ, IL-1ß, and IL-17A, and the proportion of Th17 cells in spleen cells were all reduced, while the anti-inflammatory factor IL-10 and regulatory T cell proportions were increased. Moreover, BBR treatment increased beneficial and reduced harmful bacteria in the gut. BBR also strengthened ileal barrier function by increasing the expression of the tight junction proteins zonula occludens-1 and occludin, thereby blocking lipopolysaccharide translocation, preventing lipopolysaccharide/toll-like receptor 4 (TLR4)/ NF-κB pathway activation, and inhibiting inflammatory factor production in the liver. Fecal microbiota transplantation from BBR to model mice also showed that BBR potentially alleviated AIH by altering the gut microbiota. CONCLUSIONS: BBR alleviated concanavalin A-induced AIH by modulating the gut microbiota and related immune regulation. These results shed more light on potential BBR therapeutic strategies for AIH.

The significance of gut microbiota in the etiology of autoimmune hepatitis: a narrative review.

Autoimmune hepatitis (AIH) is a chronic inflammatory disease of the liver that is mediated by autoimmunity and has complex pathogenesis. Its prevalence has increased globally. Since the liver is the first organ to be exposed to harmful substances, such as gut-derived intestinal microbiota and its metabolites, gut health is closely related to liver health, and the "liver-gut axis" allows abnormalities in the gut microbiota to influence the development of liver-related diseases such as AIH. Changes in the composition of the intestinal microbiota and its resultant disruption of the intestinal barrier and microbial transport are involved in multiple ways in the disruption of immune homeostasis and inflammation, thereby influencing the development of AIH. In terms of the mechanisms involved in immune, the gut microbiota or its metabolites, which is decreased in secondary bile acids, short-chain fatty acids (SCFAs), and polyamines, and increased in lipopolysaccharide (LPS), branched-chain amino acids (BCAA), tryptophan metabolite, amino acid, and bile acid, can disrupt immune homeostasis by activating various immune cells and immune-related signaling pathways, resulting in aberrant activation of the immune system. Clarifying this mechanism has significant clinical implications for the treatment of AIH with drugs that target intestinal microbiota and related signaling pathways. Therefore, this narrative review summarizes the progress in exploring the involvement of gut microbiota in the pathogenesis of AIH, with the aim of helping to improve the precise targeting of therapeutic treatments against AIH for the benefit of clinical AIH treatment.

6-Formylindolo[3,2-b]carbazole, a potent ligand for the aryl hydrocarbon receptor, attenuates concanavalin-induced hepatitis by limiting T-cell activation and infiltration of proinflammatory CD11b+ Kupffer cells.

FICZ (6-formylindolo[3,2-b]carbazole) is a potent aryl hydrocarbon receptor agonist that has a poorly understood function in the regulation of inflammation. In this study, we investigated the effect of aryl hydrocarbon receptor activation by FICZ in a murine model of autoimmune hepatitis induced by concanavalin A. High-throughput sequencing techniques such as single-cell RNA sequencing and assay for transposase accessible chromatin sequencing were used to explore the mechanisms through which FICZ induces its effects. FICZ treatment attenuated concanavalin A-induced hepatitis, evidenced by decreased T-cell infiltration, decreased circulating alanine transaminase levels, and suppression of proinflammatory cytokines. Concanavalin A revealed an increase in natural killer T cells, T cells, and mature B cells upon concanavalin A injection while FICZ treatment reversed the presence of these subsets. Surprisingly, concanavalin A depleted a subset of CD55+ B cells, while FICZ partially protected this subset. The immune cells showed significant dysregulation in the gene expression profiles, including diverse expression of migratory markers such as CCL4, CCL5, and CXCL2 and critical regulatory markers such as Junb. Assay for transposase accessible chromatin sequencing showed more accessible chromatin in the CD3e promoter in the concanavalin A-only group as compared to the naive and concanavalin A-exposed, FICZ-treated group. While there was overall more accessible chromatin of the Adgre1 (F4/80) promoter in the FICZ-treated group, we observed less open chromatin in the Itgam (CD11b) promoter in Kupffer cells, supporting the ability of FICZ to reduce the infiltration of proinflammatory cytokine producing CD11b+ Kupffer cells. Taken together, these data demonstrate that aryl hydrocarbon receptor activation by FICZ suppresses liver injury through the limitation of CD3+ T-cell activation and CD11b+ Kupffer cell infiltration.

COVID-19 vaccine-induced liver injury.

PURPOSE OF REVIEW: The rapid rollout and uptake of novel coronavirus disease 2019 (COVID-19) vaccines has been accompanied by a small yet noticeable accumulation of reports of liver injury occurring after vaccination. This review describes the present evidence surrounding COVID-19 vaccine-induced liver injury (VILI). RECENT FINDINGS: Liver injury occurring after the COVID-19 vaccine often presents clinically similar to autoimmune hepatitis, with positive autoantibodies and a portal and lobular inflammatory infiltrate and varying degrees of necrosis on biopsy. The overwhelming majority of patients recover, often spontaneously or with a limited course of immunosuppression. The overall incidence of this phenomenon appears to be exceedingly low. SUMMARY: Providers should remain vigilant for ongoing reports of VILI after COVID-19 and yet feel reassured by the low incidence and high likelihood of recovery. Ongoing genetic and histological study, as well as longer-term follow-up of presently identified cases, will shed further light on the clinical entity of VILI.

L-lysine supplementation attenuates experimental autoimmune hepatitis in a chronic murine model.

The incidence of autoimmune hepatitis (AIH) has increased significantly worldwide. The present study aims to explore the protective effect of L-lysine supplementation against AIH and to investigate its potential underlying mechanisms. A chronic experimental AIH mouse model was established by repeated tail vein injection of human cytochrome P450 2D6 (CYP2D6) plasmid. Starting from day 14 of the modeling, mice in the CYP2D6-AIH +L-lysine group were given 200 µl of purified water containing 10 mg/kg L-lysine by gavage until day27, once a day, and mice in the healthy control group and model group were given an equal volume of purified water by gavage. Our results showed that L-lysine supplementation partially reversed the liver injury mediated by CYP2D6 overexpression. These effects were consistent with the restraining impacts of L-lysine supplementation on decreasing pro-inflammatory cytokines expression level and CD4+ and CD8+ T lymphocytes infiltration, as well as curbing hepatic oxidative stress. Furthermore, L-lysine supplement relieved liver fibrosis in the context of AIH. In conclusion, L-lysine supplementation attenuates CYP2D6-induced immune liver injury in mice, which may serve as a novel nutrition support approach for AIH.

Defining characteristics and long-term prognosis of drug-induced autoimmune-like hepatitis: A retrospective cohort study.

BACKGROUND: Drug-induced autoimmune-like hepatitis (DI-AILH) is poorly defined and more data are required to better characterise and manage this disease entity. OBJECTIVES: The aim of this study was to evaluate the clinical characteristics, histology and long-term outcomes of DI-AILH compared with idiopathic autoimmune hepatitis (AIH). METHODS: This retrospective cohort study reviewed 28 DI-AILH and 39 AIH patients in a single centre. The new (2022) and simplified (2008) AIH histology criteria were used to assess DI-AILH. RESULTS: DI-AILH were more likely to present with jaundice (p = 0.004) and higher bilirubin levels (p = 0.04) than AIH. AIH patients had higher rate of immunosuppression (IS) use including second- and third-line agents, though the time to reach biochemical remission were comparable. AIH patients had more advanced fibrosis than DI-AILH (Ishak fibrosis score 3.5 vs. 1.9, p < 0.0001). DI-AILH more commonly had eosinophilic aggregates (18% vs. 3%, p = 0.031) and less commonly showed plasma cell aggregates (61% vs. 97%, p < 0.001) than AIH. The simplified AIH histology criteria identified 1 atypical histology within the DI-AILH cohort, although this patient required long-term IS. The new AIH histology criteria classified 23 (82%) as likely AIH and 5 (18%) as possible AIH. Two of the possible DI-AILH did not require IS and one patient had successful IS withdrawal. Four DI-AILH patients with fibrosis stage ≤3 had successful IS withdrawal compared with none in the AIH group. Four patients underwent liver transplantation (LT) in both cohorts with significantly shorter time to LT in DI-AILH as the indication was for (sub)acute liver failure. Two DI-AILH patients died within 60 days of LT. CONCLUSION: The new AIH histology criteria may be better at identifying DI-AILH. Immunosuppression withdrawal in those without significant fibrosis may be considered. DI-AILH is at risk of (sub)acute liver failure and early discussions with a transplant centre would be desirable.

Pien Tze Huang alleviates Concanavalin A-induced autoimmune hepatitis by regulating intestinal microbiota and memory regulatory T cells.

BACKGROUND: Traditional Chinese medicine has used the drug Pien Tze Huang (PTH), a classic prescription, to treat autoimmune hepatitis (AIH). However, the precise mode of action is still unknown. AIM: To investigate the mechanism of PTH in an AIH mouse model by determining the changes in gut microbiota structure and memory regulatory T (mTreg) cells functional levels. METHODS: Following induction of the AIH mouse model induced by Concanavalin A (Con A), prophylactic administration of PTH was given for 10 d. The levels of mTreg cells were measured by flow cytometry, and intestinal microbiota was analyzed by 16S rRNA analysis, while western blotting was used to identify activation of the toll-like receptor (TLR)2, TLR4/nuclear factor-κB (NF-κB), and CXCL16/CXCR6 signaling pathways. RESULTS: In the liver of mice with AIH, PTH relieved the pathological damage and reduced the numbers of T helper type 17 cells and interferon-γ, tumor necrosis factor-alpha, interleukin (IL)-1ß, IL-2, IL-6, and IL-21 expression. Simultaneously, PTH stimulated the abundance of helpful bacteria, promoted activation of the TLR2 signal, which may enhance Treg/mTreg cells quantity to produce IL-10, and suppressed activation of the TLR4/NF-κB and CXCL16/CXCR6 signaling pathways. CONCLUSION: PTH regulates intestinal microbiota balance and restores mTreg cells to alleviate experimental AIH, which is closely related to the TLR/CXCL16/CXCR6/NF-κB signaling pathway.

Clinical and Pathological Features of Immune Checkpoint Inhibitor-induced Liver Injury in Comparison with Drug-induced Liver Injury and Autoimmune Hepatitis.

BACKGROUND AND AIMS: Immune checkpoint inhibitors may cause various types of organ damage as immune-related adverse events, of which, liver damage is the most common. Herein, we evaluated the clinicopathological features of immune checkpoint inhibitor-related liver injury and investigated the differences between immune checkpoint inhibitor-related liver injury and drug-induced liver injury or autoimmune hepatitis. METHODS: We selected patients with ≥ grade 3 liver injury who were diagnosed with immune checkpoint inhibitor-related liver injury (n=15). Liver biopsies were performed in 10 of the 15 cases. We also selected cases in which a liver biopsy was performed and drug-induced liver injury (n=7) or autoimmune hepatitis [n=21: acute exacerbation (n=13) was diagnosed and cases of acute onset (n=8), in which liver function test results corresponded to ≥ grade 3]. RESULTS: Portal fibrosis and periportal activity scores were significantly higher in the acute exacerbation autoimmune hepatitis group than in the other groups. Portal and lobular activity were not different between the groups. Plasma cell infiltration showed a higher trend in the autoimmune hepatitis group than in the other groups. Granuloma formations were seen in 90% of immune checkpoint inhibitor-related liver injury cases. The CD4/8 ratio was significantly lower in the immune checkpoint inhibitor-related liver injury group than in the other groups. Patients with bile duct injury had poorer response to corticosteroid therapy than those without. CONCLUSIONS: There are some obvious differences among immune checkpoint inhibitor-related liver injury, drug-induced liver injury, and autoimmune hepatitis in liver histology. Liver biopsy is helpful for the diagnosis and severity evaluation of liver injury.

Prenyllongnols A-D, New Prenylated Acylphloroglucinols that Fight Concanavalin A-Induced Autoimmune Hepatitis.

Autoimmune hepatitis is a serious hepatic disorder with unknown nosogenesis, and natural products have been deemed to be one of the most significant sources of new drugs against this disease. Prenyllongnols A-D (1-4), four undescribed prenylated acylphloroglucinols, were isolated from Hypericum longistylum. Compounds 1-4 exhibited remarkable immunosuppressive activities in murine splenocyte proliferation under the induction of concanavalin A (Con A), and IC50 values ranged from 2.98 ± 0.21 to 6.34 ± 0.72 µM. Furthermore, in a Con A-challenged autoimmune hepatitis mouse model, the mice in the group that were pretreated with isolate 2 significantly ameliorated liver injury and decreased proinflammatory cytokine production. Notably, natural product 2 was the first prenylated acylphloroglucinol to protect against concanavalin A-induced autoimmune hepatitis. This finding underscores the potential of prenylated acylphloroglucinol-type metabolites as promising candidates for designing novel immunosuppressors in the quest for new antiautoimmune hepatitis drugs.

Dextran sulfate sodium-induced gut microbiota dysbiosis aggravates liver injury in mice with S100-induced autoimmune hepatitis.

Recently, the incidence of autoimmune hepatitis (AIH) has gradually increased, and the disease can eventually develop into cirrhosis or even hepatoma if left untreated. AIH patients are often characterized by gut microbiota dysbiosis, but whether gut microbiota dysbiosis contributes to the progression of AIH remains unclear. In this study, we investigate the role of gut microbiota dysbiosis in the occurrence and development of AIH in mice with dextran sulfate sodium salt (DSS) induced colitis. C57BL/6J mice were randomly divided into normal group, S100-induced AIH group, and DSS+S100 group (1 % DSS in the drinking water), and the experimental cycle lasted for four weeks. We demonstrate that DSS administration aggravates hepatic inflammation and disruption of the intestinal barrier, and significantly changes the composition of gut microbiota in S100-induced AIH mice, which are mainly characterized by increased abundance of pathogenic bacteria and decreased abundance of beneficial bacteria. These results suggest that DSS administration aggravates liver injury of S100-induced AIH, which may be due to DSS induced gut microbiota dysbiosis, leading to disruption of the intestinal barrier, and then, the microbiota translocate to the liver, aggravating hepatic inflammation.

Successful treatment of severe immune checkpoint inhibitor associated autoimmune hepatitis with basiliximab: a case report.

Immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1) and its corresponding ligand PD-L1 are being increasingly used for a wide variety of cancers, including refractory sarcomas. Autoimmune hepatitis is a known side effect of ICIs, and is typically managed with broad, non-specific immunosuppression. Here, we report a case of severe autoimmune hepatitis occurring after anti-PD-1 therapy with nivolumab in a patient with osteosarcoma. Following prolonged unsuccessful treatment with intravenous immunoglobulin, steroids, everolimus, tacrolimus, mycophenolate, and anti-thymoglobulin, the patient was eventually treated with the anti-CD25 monoclonal antibody basiliximab. This resulted in prompt, sustained resolution of her hepatitis without significant side effects. Our case demonstrates that basiliximab may be an effective therapy for steroid-refractory severe ICI-associated hepatitis.

Autoimmune hepatitis following COVID-19 vaccination: Clinical characteristics of 35 reported cases.

The coronavirus disease 2019 (COVID-19) vaccines have been shown to be effective in protecting people from severe disease progression, hospitalisation and death. However, a wide range of side effects have been reported worldwide. New onset or flare-up of autoimmune hepatitis (AIH) is an extremely rare adverse event following COVID-19 vaccination, with the majority of cases presenting with mild symptoms. Unfortunately, there have been cases of fatal complications. In this mini-review, we have summarised the clinical characteristics of a total of 35 currently reported cases of AIH after COVID-19 vaccination and suggest that patients with autoimmune diseases may be at higher risk of developing AIH after vaccination.