Gut microbiota and acute graft-versus-host disease.

Although allogeneic stem cell transplantation (allo-SCT) is a potentially curative treatment for various hematological diseases, acute graft-versus-host disease (GVHD) is a major cause of morbidity and mortality, and its management is clinically important. Advances in biological techniques have led to great progress in understanding the complex interactions between the host and the gut microbiota. The gut microbiota clearly modulates the immune response and is associated with the pathogenesis of various disorders. Also in allo-SCT, both preclinical and clinical results indicate that the gut microbiota is closely associated with the development of acute GVHD and transplant outcomes. These results led to the idea that improvement in quantitative and/or qualitative abnormalities of microbiota (dysbiosis) may be a new treatment strategy for acute GVHD. Evaluations of therapies targeting the gut microbiota such as probiotics or fecal microbiota transplantation have just begun. Furthermore, intervention in the gut microbiota with a nutritional approach including prebiotics, postbiotics, and antibiotics selection may also be another promising treatment option for acute GVHD.