The Potential of targeting the gut microbiota to improve allogeneic haematopoietic stem cell transplantation outcomes, focusing on graft-versus-host diseases.

Abstract

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is the treatment of choice for many haematological malignancies and benign diseases. Outcomes of allo-HSCT have improved over the years; however, there is still a high rate of transplant-related mortality, with graft-versus-host disease (GVHD) as one of the key contributors. Currently, there is an unmet need for biomarkers and new therapeutic strategies to treat GVHD. In allo-HSCT, the preparative regimen and prophylactic antibiotics may cause significant changes to the gut microbiota and the gut. The resulting dysbiosis and gut injury has been linked to the occurrence of GVHD and other major complications. This highlights the possible function of the microbiota as a biomarker and microbiota modulation as an interventional strategy. Microbiota modulation strategies can be prophylactic and therapeutic with the goal to prevent or treat dysbiosis, respectively. Prophylactic strategies include enteral nutrition, anaerobicsparing antibiotics, prebiotics, probiotics, postbiotics, and faecal microbiota transplantation (FMT). Therapeutic strategies include FMT and lactoferrin. In this review, we outline our current understanding of how microbiota can be used as a biomarker and microbiota modulation can be used as a prophylactic or therapeutic strategy to improve GVHD outcomes following allo-HSCT.