Microbial, immune, and metabolomic signatures of oral health
Creators: name: Vazana, Stephanie M.
Publisher: name: University of Iowa
Year: 2023
Subjects: public abstract

description: ABSTRACTBefore the 2017 classification of Periodontal and Peri-Implant Diseases and Conditions, a definition for a healthy periodontium was not well-established. Traditionally, the literature focus on disease pathogenesis. To better understand the disease, it is critical to define health. The health in the oral cavity is determined by the homeostatic interactions between the microbial species that colonize different niches in the form of biofilms and the resident immune cells. The primary aim of the study was to determine the microbial members, immune mediators, and the resultant end-stage molecules (metabolites) in the subgingival and salivary environments of systemically and periodontally healthy individuals using a comprehensive, integrated -omics approach.
description: METHODS60 samples collected from 20 Healthy participants from the University of Iowa College of Dentistry were used for this pilot investigation. Unstimulated saliva, subgingival plaque, and gingival crevicular fluid (GCF) samples were collected, and samples were frozen appropriately until analyses were performed. DNA isolation was performed using the Qigen DNEasy kit for the saliva and plaque samples. The GCF was eluted, and immune mediators were analyzed using Millipore Multiplex kit. 16S rRNA sequencing were performed with Illumina MiSeq platform. Analyses were conducted with DADA2, QIIME2. Taxonomy identification was determined against the HOMD database. Alpha and beta-diversity were assessed. Results were visualized with PhyloToAST and core species were identified. To assess major metabolic pathways, gas chromatography/mass spectrometry (GC/MS) analysis was processed for saliva and GCF samples at the Metabolomics Core (FOEDRC). The networks were analyzed within the context of KEGG.
description: RESULTSA total of 20 participants (60 samples) were included in the analyses. Saliva and the subgingival environments exhibited distinct microbial colonization as demonstrated by the alpha (Mann-Whitney, two-tailed p-value 0.03) and beta diversity (p=0.001, ANOSIM). Differential abundance analysis revealed that 124 species were significantly different between the two niches. Core microbiome (identified in 80% of the samples) was determined and cataloged in each of the cohort. A total of 42 immune mediators (e.g., interleukins (ILs), matrix metalloproteases (MMPs), adipokines) were quantified in GCF and saliva. Several proinflammatory mediators were undetectable within the healthy cohort. Identifiable immune mediators, such as MMP-9 and MMP-10, were expressed in higher concentrations in the subgingival environment compared to the salivary environment (p-value &lt;0.05, Wilcoxon Ranked Sum test). Metabolites that contribute to microbial-mucosal homeostasis, such as glycerol and cysteine, were identified in our data, demonstrating the potential role of these end- products in health.
description: CONCLUSIONOur pilot study has cataloged health-associated molecular parameters in the salivary and subgingival environment for the first time, thus establishing a baseline for health. Distinct microbial suites colonize subgingival and salivary environments. Constitutive immune expression is higher in a healthy periodontal (subgingival) environment compared to the salivary
description: environment. Unique metabolite signatures are associated with the two niches. Studies with larger cohort and diverse demographics need to be conducted to validate our findings and identify potential biomarkers.
description: KEYWORDSOral health, Salivary metabolites, Oral microbiome, Subgingival, Mucosal immunity, Cytokine(s), Gingival crevicular fluid, Saliva, Periodontal health, Periodontal disease(s).