Microbe-derived short chain fatty acids butyrate and propionate are associated with protection from chronic GVHD.
Studies of the relationship between the gastrointestinal microbiota and outcomes in allogeneic hematopoietic stem cell transplantation (allo-HCT) have, thus far, largely focused on early complications, predominantly infection and acute graft-versus-host disease (GVHD). We examined the potential relationship of the microbiome with chronic GVHD (cGVHD) by analyzing stool and plasma samples collected late after allo-HCT using a case-control study design. We found lower circulating concentrations of the microbe-derived short-chain fatty acids (SCFA) propionate and butyrate in day 100 plasma samples from patients who developed cGVHD, compared with those who remained free of this complication in the initial case-control cohort of transplant patients, and in a further cross-sectional cohort from an independent transplant center. An additional cross-sectional patient cohort from a third transplant center was analyzed, however serum was available – rather than plasma – and the differences in SCFA observed in the plasma samples were not recapitulated. In sum, our findings from the primary case-control cohort, and one of two cross-sectional cohorts explored, suggest that the gastrointestinal microbiome may exert immunomodulatory effects in allo-HCT patients at least in part due to control of systemic concentrations of microbe-derived short chain fatty acids.