Metabolic Reprogramming of CD4+ T Cells by Mesenchymal Stem Cell-Derived Extracellular Vesicles Attenuates Autoimmune Hepatitis Through Mitochondrial Protein Transfer.

Background: Autoimmune hepatitis (AIH) is a serious liver disease characterized by immune disorders, particularly effector T-cell overactivation. This study aimed to explore the therapeutic effect and underlying mechanism of mesenchymal stem cell-derived extracellular vesicle (MSC-EV) treatment on CD4⁺ T-cell overactivation and liver injury in AIH.

Methods: The metabolic changes of CD4⁺ T cells were assayed in human AIH and mouse hepatitis models. The liver protective effect of MSC-EVs was evaluated by transaminase levels, liver histopathology and inflammation. The effect of MSC-EVs on the metabolic state of CD4⁺ T cells was also explored.

Results: Enhanced glycolysis (eg, ~1.5-fold increase in hexokinase 2 levels) was detected in the CD4⁺ T cells of AIH patient samples and mouse hepatitis models, whereas the inhibition of glycolysis decreased CD4⁺ T-cell activation (~1.8-fold decrease in CD69 levels) and AIH liver injury (~6-fold decrease in aminotransferase levels). MSC-EV treatment reduced CD4⁺ T-cell activation (~1.5-fold decrease in CD69 levels) and cytokine release (~5-fold decrease in IFN-γ levels) by reducing glycolysis (~3-fold decrease) while enhancing mitochondrial oxidative phosphorylation (~2-fold increase in maximal respiration) in such cells. The degree of liver damage in AIH mice was ameliorated after MSC-EV treatment (~5-fold decrease in aminotransferase levels). MSC-EVs carried abundant mitochondrial proteins and might transfer them to metabolically reprogram CD4⁺ T cells, whereas disrupting mitochondrial transfer impaired the therapeutic potency of MSC-EVs in activated CD4⁺ T cells.

Conclusion: Disordered glucose metabolism promotes CD4⁺ T-cell activation and associated inflammatory liver injury in AIH models, which can be reversed by MSC-EV therapy, and this effect is at least partially dependent on EV-mediated mitochondrial protein transfer between cells. This study highlights that MSC-EV therapy may represent a new avenue for treating autoimmune diseases such as AIH.