A reasoned approach to the treatment of autoimmune hepatitis

Autoimmune-Like Hepatitis Related to SARS-CoV-2 Vaccination: Towards a Clearer Definition

Vaccines are the most effective tool against COVID-19 and are generally safe. Very rare and heterogeneous cases of acute liver injury associated to all types of SARS-CoV-2 vaccines have been reported, mostly with autoimmune features. Epidemiological studies used heterogeneous diagnostic criteria and included different populations. Immunological studies in selected cases of acute liver injury linked to mRNA SARS-CoV-2 vaccines suggest that it has a unique pathophysiology, the vaccine-encoded spike protein playing a central role in triggering the aberrant immune response. In most series, liver injury was observed more often following the second vaccine dose. Latency from vaccination to the diagnosis of hepatitis was 1-147 days after the last vaccine dose. Raised immunoglobulin G levels and positive anti-nuclear and/or anti-smooth muscle antibodies are frequent. The vast majority of reported cases have been treated with corticosteroids, mostly associated with azathioprine. Outcome is generally favourable, but cases requiring liver transplantation or causing death have been reported. The heterogeneous clinical entity of acute liver injury linked to SARS-CoV-2 vaccines includes patients requiring long-term immunosuppression, similarly to autoimmune hepatitis, and patients with self-limiting liver damage, possibly representing a unique form of autoimmune-like hepatitis, which we suggest being referred to as SARS-CoV-2 vaccine-associated liver injury (SVALI). Further studies are needed to investigate the pathogenic mechanisms related to the immune response to the spike viral protein in the liver.

Advances in the Treatment of Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is a chronic, progressive inflammatory liver disease caused by autoimmune reactions, with an unknown etiology. If left untreated, it can progress to cirrhosis, liver failure, or even death. While most patients respond well to first-line treatments, a significant number experience poor responses or intolerance, requiring the use of second- or third-line therapies. Ongoing research into the pathogenesis of AIH is leading to the development of novel therapeutic approaches. This review summarized recent advancements in the treatment of AIH both domestically and internationally.

Trends of Costs and Admission Rates Among Patients Admitted With Autoimmune Hepatitis: Analysis of US Hospitals Using the NIS Database

Background and aim

Autoimmune hepatitis (AIH) is a prominent cause of chronic liver disease in the United States. This study aims to characterize the incidence, mortality, and cost implications of this condition using a national database.

Method

The 2016-2019 National Inpatient Sample was used to select patients with AIH. After adjusting for inflation, weighted charge data were used to calculate the admission costs using charge-to-cost ratios. Demographic, socioeconomic status, and comorbidity values were used to build strata to characterize admission incidence, mortality data and aggregate and per-capita cost values. Furthermore, additional sensitivity analysis was performed using a stratified set of patients with AIH as one of the top 10 diagnosis (AIH-specific subsample). Multinomial regression curves were graphed and assessed to derive goodness-of-fit for each trend. R2 and P-values were calculated.

Results

From 2016 to 2019, the total admissions related to AIH were approximately 20,984, 21,905, 22,055, and 22,680 cases, respectively (R2: 0.93, P-value: 0.03). AIH-related hospitalization aggregate costs came to $338.18, $369.17, $355.98, and $387.25 million dollars (R2: 0.75, P-value: 0.17). Significant admission growth was seen in the Southern region (R2: 0.91, P-value: 0.05). Most notably, increasing trends in total admissions were found across older age, those of White and Hispanic descent, and those with comorbidities. On the other hand, the AIH-specific subsample illustrated decreasing trends in admissions across demographics (i.e., age, gender, and race) and comorbidities; however, those with hepatic complications saw a rise in the admission trends (cirrhosis - R2: 0.98, P-value: 0.009; multiple liver complications - R2: 0.95, P-value: 0.03).

Conclusion

Among AIH-specific admissions, there was a decreasing trend overall; however, there was an exceptional increase in the admissions among those with hepatic complications.

Itaconate attenuates autoimmune hepatitis via PI3K/AKT/mTOR pathway-mediated inhibition of dendritic cell maturation and autophagy

Autoimmune hepatitis (AIH) results from an autoimmune-mediated chronic inflammatory response against liver cells. Defective self-tolerance and dysfunctional dendritic cells (DCs) play a regulatory role in AIH. Itaconate has recently attracted attention in the field of immunometabolism because of its crucial role as an anti-inflammatory metabolite that negatively regulates the inflammatory response. However, the underlying mechanism of itaconate mediation of DCs in AIH remains unclear. In this study, we found that itaconate acts as an anti-inflammatory factor in the liver. Endogenous itaconate levels were significantly increased in mice with S100-induced AIH model and correlated with upregulation of the immune-responsive gene 1 expression. However, the anti-inflammatory response from endogenously itaconate may not represent the effects exogenously-produced itaconate. We investigated the anti-inflammatory response from exogenous itaconate in S100-induced AIH, and our results showed that itaconate treatment attenuated liver histopathological damage, hepatocyte apoptosis, aminotransferase elevation, and IL-6 production in the S100-induced AIH model. In addition, Itaconate decreased glycolysis to suppress the maturation of DCs in the liver and spleen of AIH models, thereby directly regulating differentiation of Th17 and Tregs in vivo. The percentage of Th17 cells among the CD4⁺ population were decreased and Tregs were increased (P < 0.05). Furthermore, Itaconate-induced bone marrow-derived monocytes suppressed CD4⁺cells proliferation. In vitro and in vivo, we found that itaconate suppressed autophagy via activating the PI3K/AKT/mTOR signalling pathway in bone marrow-derived DCs and liver tissues. We further investigated the function of Itaconate on DC-specific mTOR-deficient mice. mTOR-deficient DCs augmented inflammatory reactions in mTOR^DC-/- AIH mice and induced autophagy. MHY1485 (an agonist of mTOR) and itaconate significantly alleviated the inflammatory reaction and autophagy signalling. In conclusion, itaconate ameliorate liver inflammation in S100-induced AIH mice by regulating the PI3K/AKT/mTOR pathway to decrease DCs autophagy and maturation. These results provide insight useful for treating AIH.

[Treatment of Autoimmune Hepatitis]

Autoimmune hepatitis (AIH) is a chronic liver disease, characterized by elevated levels of transaminases, immunoglobulin G, and positive autoantibodies. The disease course is dynamic and presents heterogeneous disease manifestations at diagnosis. This review summarizes the issues regarding the treatment and monitoring of AIH in adult patients. Glucocorticoids and azathioprine are the first line of treatment. Alternative first-line treatments include budesonide or mycophenolate mofetil (MMF). Although no randomized controlled trials have been performed, MMF, cyclosporine, tacrolimus, 6-mercaptopurine, 6-thioguanine, allopurinol, sirolimus, everolimus, infliximab, or rituximab have been attempted in patients not responding to or intolerant to first-line treatments. Most patients require life-long special monitoring, with or without maintenance treatment.

Animal Models for Autoimmune Hepatitis: Are Current Models Good Enough?

Autoimmune liver diseases like autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis, and IgG4-related cholangitis are chronic inflammatory diseases of the liver with an autoimmune background. The therapy of autoimmune hepatitis targets the autoreactive immune system and is largely dependent on the use of glucocorticoids and cytostatic drugs. In contrast, the treatment of cholestatic autoimmune liver diseases is restricted to the use of secondary or semi-synthetic bile acids, like ursodeoxycholic acid or obeticholic acid. Although the management of the disease using such drugs works well for the majority of patients, many individuals do not respond to standard therapy. In addition, chronic treatment with glucocorticoids results in well-known side effects. Further, the use of bile acids is a symptomatic therapy that has no direct immunomodulatory effect. Thus, there is still a lot of room for improvement. The use of animal models has facilitated to elucidate the pathogenesis of autoimmune liver diseases and many potential target structures for immunomodulatory therapies have been identified. In this review, we will focus on autoimmune hepatitis for which the first animal models have been established five decades ago, but still a precise treatment for autoimmune hepatitis, as obtainable for other autoimmune diseases such as rheumatoid arthritis or multiple sclerosis has yet to be introduced. Thus, the question arises if our animal models are too far from the patient reality and thus findings from the models cannot be reliably translated to the patient. Several factors might be involved in this discrepancy. There is first and foremost the genetic background and the inbred status of the animals that is different from human patients. Here the use of humanized animals, such as transgenic mice, might reduce some of the differences. However, there are other factors, such as housing conditions, nutrition, and the microbiome that might also play an important role. This review will predominantly focus on the current status of animal models for autoimmune hepatitis and the possible ways to overcome discrepancies between model and patient.

Impact of Antigen Presentation Mechanisms on Immune Response in Autoimmune Hepatitis

The liver is a very tolerogenic organ. It is continually exposed to a multitude of antigens and is able to promote an effective immune response against pathogens and simultaneously immune tolerance against self-antigens. In spite of strong peripheral and central tolerogenic mechanisms, loss of tolerance can occur in autoimmune liver diseases, such as autoimmune hepatitis (AIH) through a combination of genetic predisposition, environmental factors, and an imbalance in immunological regulatory mechanisms. The liver hosts several types of conventional resident antigen presenting cells (APCs) such as dendritic cells, B cells and macrophages (Kupffer cells), and unconventional APCs including liver sinusoidal endothelial cells, hepatic stellate cells and hepatocytes. By standard (direct presentation and cross-presentation) and alternative mechanisms (cross-dressing and MHC class II-dressing), liver APCs presents self-antigen to naive T cells in the presence of costimulation leading to an altered immune response that results in liver injury and inflammation. Additionally, the transport of antigens and antigen:MHC complexes by trogocytosis and extracellular vesicles between different cells in the liver contributes to enhance antigen presentation and amplify autoimmune response. Here, we focus on the impact of antigen presentation on the immune response in the liver and on the functional role of the immune cells in the induction of liver inflammation. A better understanding of these key pathogenic aspects could facilitate the establishment of novel therapeutic strategies in AIH.