Intestinal Microbiome-based Research for the Prevention of Acute GVHD

Hematopoietic stem cell transplantation consists of preconditioning chemotherapy, stem cell infusion, and engraftment of hematopoietic stem cells. In this process, in the case of recipients who receive hematopoietic stem cells, their immune system is completely destroyed and then undergoes a situation in which it is reconstituted. In this process, the diversity of the intestinal microbiome is reduced, and it is widely known that a severe decrease is associated with the occurrence of an acute graft-versus-host reaction. Attempts to improve the intestinal microbiome include prebiotics, probiotics, and postbiotics. Prebiotics can be expected to improve the intestinal microbiome by acting as nutrients for beneficial bacteria in the intestine, but their role may be limited in situations where the diversity of the intestinal microbiome has already decreased. Probiotics are a method to expect improvement of the intestinal microbiome by administering the beneficial bacteria themselves in the intestine, but there is a difficulty in reaching the intestine properly through stomach acid, and there is a risk of causing sepsis in immunocompromised patients. Postbiotics is a product that beneficial bacteria metabolize and release prebiotics in the intestine, and the microbiome in the intestine is actually responsible for the function that affects the human body. Therefore, in this study, postbiotics are administered to patients undergoing hematopoietic stem cell transplantation who are concerned that the diversity of the intestinal microbiome may have already decreased, to improve the intestinal microbiome and hope to prevent graft-versus-host reactions through this. Furthermore, it is intended to improve the outcome of allogeneic hematopoietic stem cell transplantation.