Intestinal Microbiota at Engraftment Influence Acute Graft-Versus-Host Disease <i>via</i> the Treg/Th17 Balance in Allo-HSCT RecipientsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked how the intestinal microbiota relates to T cell immune balance in patients who developed acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation. It analyzed fecal microbiota and blood T cell subsets at the time of engraftment. Microbiota was profiled by 16S rRNA gene sequencing. Treg and Th17 cells and histone H3 acetylation in CD4+ T cells were measured by flow cytometry.
Who was studied?
The analysis included 81 adult allo-HSCT recipients, split into 32 patients with grades II-IV aGVHD and 49 patients with grade 0-I aGVHD. Patients ranged in age from 16 to 54 years, with a median of 33. All were human transplant recipients treated at a single hospital in China. Fecal and blood samples were collected within 72 hours of engraftment. The cohort came from an original 99 patients, with 18 excluded for early death or unusable specimens.
What were the most important findings?
The aGVHD group had lower microbial diversity (inverse Simpson 1.78 versus 3.03, p = 0.035). Their microbiota was depleted of Clostridia families Lachnospiraceae and Ruminococcaceae (p = 0.001 and 0.007) and the Blautia genus, and enriched for Gammaproteobacteria and Enterobacteriaceae (p = 0.023). Lachnospiraceae and Ruminococcaceae abundance positively correlated with the Treg/Th17 ratio (r = 0.469 and 0.419, p < 0.001), while Enterobacteriaceae correlated negatively (r = -0.277, p = 0.012). Acetylated H3 in CD4+ T cells was lower in aGVHD and correlated with both these bacteria and the Treg/Th17 ratio (r = 0.354, p = 0.001).
What are the greatest implications of this study?
The results suggest gut bacteria may influence aGVHD by shaping the Treg/Th17 immune balance, possibly acting through histone H3 acetylation in CD4+ T cells. This offers a candidate mechanism linking microbiota loss to transplant complications in humans. The authors note this points to replenishing Lachnospiraceae and Ruminococcaceae or restricting Enterobacteriaceae as future strategies. As a correlational study at a single center, it shows association, not proven causation.