Autoimmune hepatitis (AIH) is detected at a late stage in the course of the disease. Therefore, induction and etiology are largely unclear. It is controversial if the induction of autoimmunity occurs in the liver or in the spleen. In our experimental murine AIH model, the induction of autoimmunity did not occur in the spleen. Instead, a protective role of the spleen could be more likely. Therefore, we splenectomized mice followed by induction of experimental murine AIH. Splenectomized mice presented more severe portal inflammation. Furthermore, these mice had more IL-17, IL-23 receptor (IL-23R) and caspase 3 (casp3) and a decreased amount of erythropoietin in serum, while intrahepatic T cell compartments were unaffected. These results indicate that the spleen is not necessary for induction of AIH, and splenectomy disrupts the ability to immune regulate the intensity of hepatic inflammation, production of IL-17 and apoptosis.
Dysregulation of glucose homeostasis plays a major role in the pathogenesis of non-alcoholic steatohepatitis (NASH) as it activates proinflammatory and profibrotic processes. Beneficial effects of antiglycemic treatments such as GLP-1 agonist or SGLT-2 inhibitor on NASH in patients with diabetes have already been investigated. However, their effect on NASH in a non-diabetic setting remains unclear. With this aim, we investigated the effect of long-acting GLP1-agonist dulaglutide and SGLT-2 inhibitor empagliflozin and their combination in a non-diabetic mouse model of NASH. C57BL/6 mice received a high-fat-high-fructose (HFHC) diet with a surplus of cholesterol for 16 weeks. After 12 weeks of diet, mice were treated with either dulaglutide, empagliflozin or their combination. Dulaglutide alone and in combination with empagliflozin led to significant weight loss, improved glucose homeostasis and diminished anti-inflammatory and anti-fibrotic pathways. Combination of dulaglutide and empagliflozin further decreased MoMFLy6CHigh and CD4+Foxp3+ T cells. No beneficial effects for treatment with empagliflozin alone could be shown. While no effect of dulaglutide or its combination with empaglifozin on hepatic steatosis was evident, these data demonstrate distinct anti-inflammatory effects of dulaglutide and their combination with empagliflozin in a non-diabetic background, which could have important implications for further treatment of NASH.
Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common cause of chronic liver disease, especially in patients with severe obesity. However, current mouse models for MASLD do not reflect the polygenetic background nor the metabolic changes in this population. Therefore, we investigated two novel mouse models of MASLD with a polygenetic background for the metabolic syndrome. TALLYHO/JngJ mice and NONcNZO10/LtJ mice were fed a high-fat- high-carbohydrate (HF-HC) diet with a surplus of cholesterol diet. A second group of TH mice was additional treated with empagliflozin. After sixteen weeks of feeding, both strains developed metabolic syndrome with severe obesity and histological manifestation of steatohepatitis, which was associated with significantly increased intrahepatic CD8+cells, CD4+cells and Tregs, contributing to a significant increase in pro-inflammatory and pro-fibrotic gene activation as well as ER stress and oxidative stress. In comparison with the human transcriptomic signature, we could demonstrate a good metabolic similarity, especially for the TH mouse model. Furthermore, TH mice also developed signs of kidney injury as an extrahepatic comorbidity of MASLD. Additional treatment with empagliflozin in TH mice attenuates hepatic steatosis and improves histological manifestation of MASH. Overall, we have developed two promising new mouse models that are suitable for preclinical studies of MASLD as they recapitulate most of the key features of MASLD.
The priming of T cells in the liver is widely accepted. Nonetheless, it is controversial whether immune activation in autoimmune hepatitis (AIH) occurs in the liver or in the spleen. To address this issue, we splenectomized mice and induced experimental murine AIH (emAIH) with an adenovirus (Ad)-expressing formiminotransferase cyclodeaminase (FTCD). Post-splenectomy, the experimental mice developed emAIH to a higher extent than the control mice. In addition, splenectomized mice harboured more intrahepatic B cells and a disproportionately small number of regulatory T cells (Tregs) within a reduced T cell population at the site of inflammation. These results imply that the spleen is not the site of AIH induction. In contrast, the spleen seems to have a protective function since the pathological score was more severe in splenectomized animals. These findings have important implications for the aetiology of AIH.
The recognition and neutralization of tumour cells is one of the big challenges in immunity. The immune system has to recognize syngeneic tumour cells and has to be primed and respond in an adequate manner. Priming of a leukaemia-specific immune response is a crucial step in tumour immunology that can mislead to tumour tolerance either by T cell ignorance, deletion or Treg induction. To resemble the situation of acute lymphoblastic leukaemia (ALL) in patients, we used the murine BALB/c model with syngeneic BM185 tumour cells. We established a tumour cell line that expresses the neo-antigen ovalbumin (BM185-OVA/GFP) to allow the application of T cell receptor transgenic, antigen-specific CD4(+) T cells. Here, we demonstrate that effective anti-ALL immunity can be established by in vivo priming of CD4(+) T cells that is sufficient to differentiate into effector cells. Yet they failed to control tumour alone, but initiated a Th1 response. An efficient tumour clearance was dependent on both antigen-specific CD4(+) T cells and CD8(+) effector T cells from the endogenous repertoire. The tolerogeneic milieu was characterized by increased Tregs numbers and elevated IL-10 level. Tregs hamper effective antitumour immune response, but their depletion did not result in reduced tumour growth. In contrast, neutralization of IL-10 improved median mouse survival. Future therapies should focus on establishing a strong CD4+ T cells response, either by adjuvant or by adoptive transfer.
The German Biosecurity Programme was launched in 2013 with the aim to support partner countries overcome biological threats including natural outbreaks or the intentional misuse of highly pathogenic agents. As part of this programme, this paper describes the development and implementation of a multilateral biosafety and biosecurity training initiative, called 'Global Partnership Initiated Biosecurity Academia for Controlling Health Threats' (GIBACHT). To achieve its objectives, GIBACHT implemented a blended-learning approach with self-directed, distance-based learning phases and three training-of-trainer workshops. The programme follows Kirkpatrick's model of learning to guarantee sustainable effects of improved knowledge and skills. One hundred nine fellows from 26 countries have been trained in seven cohorts. Many GIBACHT alumni have established additional biosafety/biosecurity trainings in their home countries. The knowledge exchange is strengthened by the implementation of a Moodle-based alumni network. GIBACHT has the potential to contribute to strengthening the capacities of partner countries in Africa, the Middle East, and South and Central Asia to respond and build resilience to biological threats.
For the development of autoimmune hepatitis (AIH), genetic predisposition and environmental triggers are of major importance. Although experimental AIH can be induced in genetically susceptible mice, the low precursor frequency of autoreactive T cells hampers a deeper analysis of liver-specific T cells. Here, we established a system where the model antigen hemagglutinin (HA) is expressed exclusively in hepatocytes of Rosa26-HA mice following administration of a replication deficient adenovirus expressing Cre recombinase (Ad-Cre). Under these conditions, hepatocytes mimic the generation of altered-self neoantigens. To follow autoreactive T cells during AIH, we adoptively transferred HA-specific Cl4-TCR and 6.5-TCR T cells into Ad-Cre infected Rosa26-HA mice. Alternatively, Rosa26-HA mice have been crossed with TCR transgenic mice that were infected with Ad-Cre to break hepatic tolerance and induce the expression of the HA antigen as a hepatic self-antigen. Surprisingly, neither adoptive transfer nor a very high precursor frequency of autoreactive T cells was able to break tolerance in the context of adenoviral infection. The low proliferation of the antigen experienced autoreactive T cells despite the presence of the autoantigen and inflammation points to anergy as a potential tolerance mechanism. This model underscores the crucial importance of genetic susceptibility to break tolerance against hepatic autoantigens.
Autoimmune hepatitis (AIH) is a chronic inflammatory autoimmune disease of the liver. It involves a T-cell mediated autoimmune response against liver autoantigens, which leads to a loss of tolerance. AIH requires Lifelong immunosuppressive therapy, but this does not lead to a cure for AIH. For this reason, new therapeutic options are needed. One therapeutic approach is cell therapy with regulatory T cells (Treg). The aim of this cell therapy is the restoration of immunotolerance between regulatory and effector T cells. The genetic modification of Tregs with chimeric antigen receptors (CAR) can induce immunological tolerance specifically in inflamed tissue and thus serve as a possible therapy against immune mediated diseases. The CARs contain a tissue-specific single chain fragment (scFv), which ensures enrichment in inflamed liver tissue. To generate liver-specific CAR Tregs, highly specific scFvs were isolated by phage display. These scFvs were tested for specific binding of murine as well as human protein. Different second generation CAR constructs were engineered with these scFvs, which contain two intracellular signaling domains linked to a transmembrane domain. Downstream activation is triggered by specific binding of the scFvs to the target protein. The functionality of the CARs is tested in an NFAT-GFP reporter T cell line. This assay showed that the CARs specifically recognize the antigen without any autoreactivity. As proof of concept studies, the CAR Tregs were tested in disease relevant mouse models of AIH with a focus on stability, migration and effectiveness. In conclusion liver-specific Tregs are a promising therapeutic option for AIH.
Autoimmune polyendocrine syndrome type 1 (APS‐1) is caused by mutations of the autoimmune regulator ( AIRE) gene. Mouse studies have shown that this results in defective negative selection of T cells and defective early seeding of peripheral organs with regulatory T cells (Tregs). Aire deficiency in humans and mice manifests as spontaneous autoimmunity against multiple organs, and 20% of patients develop an autoimmune hepatitis (AIH). To study AIH in APS‐1, we generated a murine model of human AIH on a BALB/c mouse background, in which Aire is truncated at exon 2. A subgroup of 24% of mice is affected by AIH, characterized by lymphoplasmacytic and periportal hepatic infiltrates, autoantibodies, elevated aminotransferases, and a chronic and progressive course of disease. Disease manifestation was dependent on specific Aire mutations and the genetic background of the mice. Though intrahepatic Treg numbers were increased and hyperproliferative, the intrahepatic CD4/CD8 ratio was decreased. The targets of the adaptive autoimmune response were polyspecific and not focussed on essential autoantigens, as described for other APS‐1‐related autoimmune diseases. The AIH could be treated with prednisolone or adoptive transfer of polyspecific Tregs. Conclusion : Development of AIH in APS‐1 is dependent on specific Aire mutations and genetic background genes. Autoimmune response is polyspecific and can be controlled by steroids or transfer with Tregs. This might enable new treatment options for patients with AIH. (H epatology 2015;61:1295–1305)
