Dental Biofilm Microbiota Dysbiosis Is Associated With the Risk of Acute Graft-<i>Versus</i>-Host Disease After Allogeneic Hematopoietic Stem Cell TransplantationOriginal 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 tested whether dental plaque bacteria change during stem cell transplant and whether those changes predict acute graft-versus-host disease (aGVHD). It is the first to profile the dental biofilm microbiota in this setting with high-throughput sequencing. Supragingival plaque was swabbed at three phases: preconditioning, aplasia, and engraftment. Bacteria were profiled by 16S rRNA V3-V4 sequencing. Diversity, genus abundance, and bacterial blooms were linked to aGVHD risk using competing-risk regression.
Who was studied?
The cohort was 30 patients who underwent allogeneic hematopoietic stem cell transplant at a single Brazilian hospital between 2016 and 2018. Median age was 50, ranging from 19 to 73, and 53% were male. Acute leukemia was the most common underlying disease (60%). Most received reduced-intensity conditioning and peripheral blood grafts. Fifteen patients developed grade II-IV aGVHD, and 6 of those developed severe grade III-IV disease. Standard clinical factors did not predict aGVHD risk.
What were the most important findings?
Dental biofilm diversity fell significantly during transplant, with median Shannon index dropping from 4.15 at preconditioning to 2.75 at engraftment. Commensal genera like Streptococcus, Corynebacterium, Veillonella, and Rothia declined while Enterococcus and Mycoplasma rose. High Streptococcus or Mycoplasma at preconditioning raised aGVHD risk (HR 2.89 and 2.74), while high Veillonella lowered it (HR 0.24). A Streptococcus-to-Veillonella ratio above 1 also predicted lower risk (HR 0.23). An Enterococcus bloom occurred in 17% of patients. Every patient with a bloom developed aGVHD, strongly raising risk (HR 4.07) and severe aGVHD risk (HR 6.82).
What are the greatest implications of this study?
The findings suggest dental plaque bacteria could serve as an accessible, non-fecal marker of dysbiosis predicting aGVHD before transplant. An Enterococcus bloom in the mouth may reflect or feed a systemic process driving disease. This was a single-center exploratory study of 30 heterogeneous patients, and associations are correlational. Validation cohorts, synchronous stool sampling, and metabolomics are needed. If confirmed, oral care or targeted antimicrobial approaches might help prevent aGVHD.