ADAR1 improved Treg cell function through the miR-21b/Foxp3 axis and inhibits the progression of acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

•ADAR1 mRNA is downregulated in peripheral blood of aGVHD patients.•ADAR1 binds with the pri-miR-21b to inhibit miR-21b production.•ADAR1 promotes Treg proliferation and immunosuppressive effect.•FOXP3 is a targeted and negatively regulated by miR-21b.•ADAR1 increases Treg proportion and relieves aGVHD in mice.