Microbiome, GvHD, and immune reconstitution in allogeneic hematopoietic cell transplantation

The gut microbiota has emerged as a critical factor influencing outcomes following allogeneic hematopoietic cell transplantation (alloHCT). Notably, disruptions to the intestinal microbiome-referred to as dysbiosis-have been strongly linked to the development of acute graft-versus-host disease (aGVHD). The gut microbiome interacts closely with the host immune system, influencing both immune reconstitution and alloHCT complications. As a result, microbiome-targeted strategies are being investigated to improve outcomes and include antibiotic stewardship, prebiotic and diet intervention, probiotics including fecal microbiota transfer (FMT) and postbiotics. These approaches are being investigated not only as a therapeutic intervention in particular for aGVHD, but also as preventive strategies.