Salivary interleukin-1β response is associated with microbiome diversity

Abstract

OBJECTIVES: The study investigated the association of the salivary microbiome diversity with salivary Interleukin- 1 β (IL-1β) levels. METHODS: 90 systemically healthy subjects’ under supportive dental care were included. Unstimulated whole saliva, clinical and demographic parameters including history of chronic periodontitis were recorded. 16SrRNA V3-V4 gene amplicons from salivary DNA were subjected to Illumina MISEQ 300 base paired-end sequencing. Data was processed in the Qiime pipeline to generate an OTU table and normalized for differences in read counts per sample. Alpha and beta microbial diversity measures were generated. Mann Whitney U tests for variation of IL- 1β distribution with clinical measures, multiple alpha diversity measures’ (Chao1, Phylogenetic diversity, Shannon) correlation with IL- 1β (Spearman’s rank correlation coefficient) was analyzed. Percentage variation in IL- 1β effected by global community composition was analyzed by relating with weighted Unifrac distance beta metrics using Adonis, a nonparametric statistical method. RESULTS: Salivary IL- 1β distribution did not vary significantly with past history of chronic periodontitis (p= 0.596, Mann-Whitney U test). 4187694 non-chimeric 16SrRNA sequences were clustered into 5238 OTUs and mapped to 301 unique taxa. Alpha diversity metrics; Chao1 (r=-0.293,p=0.009), Phylogenetic diversity (r =-0.333, p=0.001) Shannon (r=-0.282, p=0.007) were significantly negatively correlated with salivary IL- 1β levels. Weighted Unifrac beta diversity metric was significantly associated with IL- 1β (p= 0.4296). CONCLUSIONS: Decreased richness and phylogenetic diversity of the salivary microbiome was linked to greater salivary IL- 1β levels in subjects under supportive dental care. The study demonstrated that differences in community composition and a richer salivary microbiome seem to associate with a healthier host physiologic status.