Exploration the significance of Tfh and related molecules on C57BL/6 mice model of experimental autoimmune hepatitis

The double roles of T cell-mediated immune response in the progression of MASLD

Metabolic dysfunction-associated steatotic liver disease(MASLD), formerly known as non-alcoholic fatty liver disease(NAFLD), has become a major cause of chronic liver disease and a significant risk factor for hepatocellular carcinoma, which poses a huge burden on global public health and economy. MASLD includes steatotic liver disease, steatohepatitis, and cirrhosis, and the latter two cause great harm to human health and life, even complicated with liver cancer. Immunologic mechanism plays a major role in promoting its development into hepatitis and cirrhosis. Now more and more evidences show that T cells play an important role in the progression of MASLD. In this review, we discuss the double roles of T cells in MASLD from the perspective of T cell response pathways, as well as new evidences regarding the possible application of immunomodulatory therapy in MASH.

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.

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)-1β, 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.

β-arrestin2 deficiency ameliorates S-100-induced autoimmune hepatitis in mice by inhibiting infiltration of monocyte-derived macrophage and attenuating hepatocyte apoptosis

Autoimmune hepatitis (AIH) is a progressive hepatitis syndrome characterized by high transaminase levels, interface hepatitis, hypergammaglobulinemia, and the presence of autoantibodies. Misdiagnosis or delayed treatment of AIH can lead to cirrhosis or liver failure, which poses a major risk to human health. β-Arrestin2, a key scaffold protein for intracellular signaling pathways, has been found to be involved in many autoimmune diseases such as Sjogren's syndrome and rheumatoid arthritis. However, whether β-arrestin2 plays a role in AIH remains unknown. In the present study, S-100-induced AIH was established in both wild-type mice and β-arrestin2 knockout (Arrb2 KO) mice, and the experiments identified that liver β-arrestin2 expression was gradually increased, and positively correlated to serum ANA, ALT and AST levels during AIH progression. Furthermore, β-arrestin2 deficiency ameliorated hepatic pathological damage, decreased serum autoantibody and inflammatory cytokine levels. β-arrestin2 deficiency also inhibited hepatocyte apoptosis and prevented the infiltration of monocyte-derived macrophages into the damaged liver. In vitro experiments revealed that β-arrestin2 knockdown suppressed the migration and differentiation of THP-1 cells, whereas β-arrestin2 overexpression promoted the migration of THP-1 cells, which was regulated by the activation of the ERK and p38 MAPK pathways. In addition, β-arrestin2 deficiency attenuated TNF-α-induced primary hepatocyte apoptosis by activating the Akt/GSK-3β pathway. These results suggest that β-arrestin2 deficiency ameliorates AIH by inhibiting the migration and differentiation of monocytes, decreasing the infiltration of monocyte-derived macrophages into the liver, thereby reducing inflammatory cytokines-induced hepatocytes apoptosis. Therefore, β-arrestin2 may act as an effective therapeutic target for AIH.

Fecal microbiota transplantation regulates TFH/TFR cell imbalance via TLR/MyD88 pathway in experimental autoimmune hepatitis

Objective

Autoimmune hepatitis (AIH) is a chronic immune-mediated inflammatory liver disease. Intestinal flora disturbance in AIH is closely related to TFH/TFR cell imbalances. As a new method of microbial therapy, the role of fecal microbiota transplantation (FMT) in AIH remains elusive. Here, we attempted to verify the functional role and molecular mechanism of FMT in AIH.

Methods

An experimental autoimmune hepatitis (EAH) mouse model was established to mimic the characteristics of AIH. H&E staining was used to detect histological features in mouse liver tissues. Serological tests were employed to identify several liver function biomarkers. Flow cytometry was utilized to examine the status of TFH/TFR cell subsets. Western blotting was used to evaluate TLR pathway-associated protein abundance. RT‒qPCR was applied to evaluate Treg cell markers and inflammation marker levels in mouse liver tissues.

Results

There was significant liver inflammation and dysregulated TFR/TFH cells with elevated levels of liver inflammation-associated biomarkers in EAH mice. Interestingly, transferring therapeutic FMT into EAH mice dramatically reduced liver injury and improved the imbalance between splenic TFR and TFH cells. FMT treatment also reduced elevated contents of serum alanine transaminase (ALT), aspartate aminotransferase (AST), and total bilirubin (TBIL) in EAH mice. Furthermore, therapeutic FMT reversed the increased levels of IL-21 while promoting IL-10 and TGF-β cytokines. Mechanistically, FMT regulated TFH cell response in EAH mice in a TLR4/11/MyD88 pathway-dependent manner.

Conclusion

Our findings demonstrated that liver injury and dysregulation between TFR and TFH cells in EAH might be reversed by therapeutic FMT via the TLR4/11-MyD88 signaling pathway.

Fecal Microbiota Transplantation Controls Progression of Experimental Autoimmune Hepatitis in Mice by Modulating the TFR/TFH Immune Imbalance and Intestinal Microbiota Composition

Intestinal microbiota (IM) dysbiosis contributes to the development of autoimmune hepatitis (AIH). This study aimed to investigate the potential effect of fecal microbiota transplantation (FMT) in a murine model of experimental AIH (EAH), a condition more similar to that of AIH patients. Changes in the enteric microbiome were determined in AIH patients and EAH mice. Moreover, we established an experimental model of secondary EAH mice harboring dysbiosis (ABx) to analyze the effects of therapeutic FMT administration on follicular regulatory T (TFR) and helper T (TFH) cell imbalances and IM composition in vivo. Alterations of the IM composition and bacterial translocation occurred in AIH patients compared to nonalcoholic fatty liver disease patients and healthy controls (HCs). Therapeutic FMT significantly attenuated liver injury and bacterial translocation and improved the imbalance between splenic TFR cells and TFH cells in ABx EAH mice. Furthermore, therapeutic FMT also partially reversed the increasing trend in serum liver enzymes (ALT and AST) of CXCR5-/-EAH mice on the 28th day. Finally, therapeutic FMT could effectively restore antibiotic-induced IM dysbiosis in EAH mice. Taken together, our findings demonstrated that FMT was capable of controlling hepatitis progression in EAH mice, and the associated mechanism might be involved in the regulation of the TFR/TFH immune imbalance and the restoration of IM composition.

The Function of T Follicular Helper Cells in the Autoimmune Liver Diseases

T follicular helper (TFH) cells are recognized as a subtype of T cells that are involved in the germinal center formation and B cell development. When dysregulated, TFH cells may represent an important mechanism that contributes to a heightened humoral response and autoantibody production in autoimmune liver diseases (AILDs). TFH cells participate in the immune response associated with AILDs by expressing surface receptors such as programmed cell death protein-1, C-X-C motif chemokine receptor 5, and inducible T cell costimulators, as well as cytokines such as interleukin-21. TFH cells also downregulate chemokine (C-C motif) receptor 7 and promote the dysregulation of the T follicular regulatory/TFH axis. This review highlights the importance of TFH cells in AILDs.