Decreased Foxp3 and function of Tregs caused immune imbalance and liver injury in patients with autoimmune liver diseases post-liver transplantation

Background

Autoimmune liver diseases (AILD) is a type of autoimmune disease which may cause end-stage liver failure and require liver transplantation. Regulatory T cells (Tregs) play an irreplaceable role in maintaining immunological homeostasis.

Methods

In this study, we made a comparative analysis of the immune balance and graft function between AILD patients’ post-transplantation and the patients who have had liver failure with hepatitis B virus (HBV) infection post-transplantation. Immune cell phenotype of two groups were analyzed. We sorted CD4+CD25+CD127-Tregs both in vitro and vivo and did TSDR methylation status assay to explore further possible mechanisms.

Results

Our data showed that there is a worse prognosis with severe graft function in liver transplant patients with AILD compared to patients with HBV-induced liver failure. Immune cell phenotype analysis showed that more Tregs could be detected in AILD patients compared with HBV patients’ post-transplantation. We sorted CD4+CD25+CD127-Tregs in vivo and showed that Tregs presented decreased function both in vitro and vivo. Mechanism study also proved that modulation of the phosphorylation level of STAT1 and STAT3 as well as the methylation level of TSDR in Foxp3 might partially result in the function loss of Tregs.

Conclusions

These results suggest that loss of Foxp3 expression and suppressive function of Tregs may be the critical factor that causes graft loss for liver transplant patients after AILD.

Dysregulation and impaired anti-bacterial potential of mucosal-associated invariant T cells in autoimmune liver diseases

Autoimmune liver diseases (AILD) encompass a group of conditions in which the immune system mistakenly attacks the liver tissue. Mucosal-associated invariant T (MAIT) cells are enriched in the liver, where they play crucial roles in antibacterial defense and inflammation regulation. Compared to other autoimmune conditions affecting the synovium of the joints, MAIT cells from AILD exhibited a greater deficiency in ratio, elevated activation markers, increased apoptosis, and higher pro-inflammatory cytokines production. However, the frequency of MAIT cells in AILD was negatively correlated with anti-bacterial indexes, and their impaired responsiveness and weakened anti-bacterial potential were evidenced by reduced expansion ability, lower maximal IFN-γ production, and diminished E. coli-induced cytotoxic mediators release. Similar shifts in MAIT cell ratios and phenotypes were observed in both primary biliary cirrhosis and autoimmune hepatitis, linked to upregulation of bile acid components in the affected tissue. Specifically, ursodeoxycholic acid, a metabolic intermediate and traditional anti-primary biliary cirrhosis drug, inhibited TCR-mediated expansion and downregulated pro-inflammatory cytokines and anti-bacterial-related mediators in MAIT cells. These findings underscore the intricate interplay between hepatic pathology and MAIT cells, and highlight the importance of antibacterial monitoring during ursodeoxycholic acid treatment in AILD.