The Microbiome and Allogeneic Stem Cell Transplantation

Abstract

Graft-versus-host disease (GvHD) is the major cause of mortality and morbidity after allogeneic stem cell transplantation. Recently, deep sequencing of the hypervariable regions of the 16S rRNA gene in stool specimens significantly enhanced our understanding of a likely pathophysiologic role of the microbiome in GvHD. Here, we summarize the indirect and direct evidence for a microbiome involvement. Indirect evidence for a role of the intestinal microbiota has been provided by experiments in germ-free mice and single nucleotide polymorphism analysis of receptors of innate immunity. Direct 16S rRNA sequencing showed a substantial loss of diversity in stool specimens from patients with GvHD, which is associated with inferior outcomes. We discuss mechanisms such as interference with antimicrobial peptides and potential approaches to reduce complications by microbiome modulation.