Expansion of effector regulatory T cells in steroid-responders of severe alcohol-associated hepatitis

While steroid therapy is the preferred treatment for severe alcohol-associated hepatitis, the role of effector regulatory T (eTreg) cells and their association with steroid response and clinical outcomes in these patients remains to be elucidated. We prospectively enrolled 47consecutive patients with alcohol-associated hepatitis, consisting of severe alcohol-associated hepatitis treated with steroid (n=18; steroid-treated group) and mild alcohol-associated hepatitis (n=29; non-treated group). After isolating peripheral blood mononuclear cells (PBMCs) from the patients at enrollment and again 7 days later, eTreg cells frequency was examined using flow cytometry. Single-cell RNA sequencing analysis was conducted using paired PBMCs. In vitro experiments were also performed to assess phenotype changes and the suppressive function of Treg cells following steroid treatment. The steroid-treated group exhibited significantly higher Model for End-Stage Liver Disease (MELD) scores than the non-treated group ( P <0.01). Within the steroid-treated group, the proportion of eTreg cells significantly expanded in the steroid responders (n=13; P=0.01). Furthermore, a significant positive correlation was observed between the decrease in MELD score and the increase in eTreg cells ( P <0.05). Single-cell RNA sequencing using paired peripheral blood mononuclear cells (pre- and post-steroid therapy) from a steroid responder revealed gene expression changes in T cells and monocytes, suggesting enhancement of Treg cell function. In vitro results showed an elevation in eTreg cells proportion after steroid therapy. In conclusion, our findings suggest that the efficacy of steroid therapy in patients with severe alcohol-associated hepatitis is mediated by an increase in the number of eTreg cells.