Lasting <i>Gammaproteobacteria</i> profile changes characterized hematological cancer patients who developed oral mucositis following conditioning therapyOriginal 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 longitudinal study asked how the oral microbiome changes in cancer patients who develop oral mucositis after conditioning therapy before stem cell transplant. It used 16S rRNA (V3-V4) next-generation sequencing with species-level probe matching. Samples spanned three time points: pre-conditioning, mucositis onset, and one year later. Four oral sites were sampled: saliva, buccal mucosa, tongue, and supragingival plaque. Analyses included alpha- and beta-diversity, PERMANOVA, and linear discriminant analysis effect size.
Who was studied?
The cohort was 22 hematological cancer patients undergoing conditioning therapy before hematopoietic stem cell transplant, recruited in Charlotte, North Carolina. Both autologous and allogeneic transplant recipients were included. Patients were split into Muc0-1 (WHO mucositis score 0 to 1, 43 paired samples) and Muc2 (WHO score 2, 36 paired samples). Around 114 individual oral samples formed the paired sets. Some patients received prophylactic antibiotics or total body irradiation.
What were the most important findings?
The moderate-mucositis group (Muc2) showed significant alpha-diversity change from mucositis onset to one year, while the Muc0-1 group did not. This indicates the Muc2 microbiome did not return to its baseline state. Proteobacteria drove the differences between groups by PERMANOVA and ROC analyses. From baseline to one year, a mucosa-protective species declined in Muc2, while Proteobacteria and other gram-negative genera increased. Baseline communities were similar across groups, suggesting a comparable starting point before therapy.
What are the greatest implications of this study?
The findings suggest moderate oral mucositis is accompanied by a durable oral microbiome shift, favoring gram-negative Proteobacteria at the expense of a protective species, persisting up to one year. This positions the oral microbiome as a possible exacerbator of mucositis. Effect sizes were small and species-level and strain-level resolution was limited, so the taxa cannot yet serve as validated predictors. Larger cohorts with functional and strain-level analysis are needed.