Alternation of salivary microbiome and Lautropia dominancy after allogenic hematopoietic stem cell transplantation

Objective

In a patient with hematological malignancy, oral microbiome is disturbed during chemotherapy including hematopoietic stem cell transplantation (HSCT). A critical role of salivary microbiota has not been fully investigated.

Methods

We collected saliva of 6 HSCT recipients before and after (around 30 day) transplantation, and characterized patterns of oral microbiota. We set up a healthy control cohort (N = 6) as a normal reference. A two-step PCR protocol was used to amplify a 16S rDNA in the V3-V4 region. Sequencing of the amplicons was performed on an Illumina MiSeq (Illumina). A significance of alpha and beta diversity of microbiota, and taxonomic composition were investigated.

Results

The patients’ characteristics were median age 43 years old (range 39–58) and 4 female patients. The diversity of microorganisms in saliva were significantly decreased after HSCT. Shannon index (t-test, P = 0.03) and Simpson index (P = 0.06) were significantly lower in recipients after HSCT comparing to before HSCT. In recipients experienced severe (>grade 2) oral mucositis, alpha index was less diverse compared to recipients with mild or moderate oral mucositis, and in whose saliva genus Lautropia were predominant after HSCT. A common observation of salivary microbiota after HSCT were significant increase of phylum Actinomycetacea and genus Actinomyces. Genus Neisseria was significantly decreased after HSCT.

Conclusions

We observed substantial decreases in the number and diversity of salivary microbiota through HSCT in recipient with hematological malignancy. Lautropia is newly found microorganism, which is possible to linked to mitigation of severe oral mucositis.