Determining bacterial and host contributions to the human salivary metabolome

Alexander Gardner,Harold G Parkes,Po-Wah So,Guy H Carpenter

doi:10.1080/20002297.2019.1617014

Alexander Gardner, Harold G Parkes + Show 2 more

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https://doi.org/10.1080/20002297.2019.1617014

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Abstract

ABSTRACTBackground: Salivary metabolomics is rapidly advancing.Aim and methods: To determine the extent to which salivary metabolites reflects host or microbial metabolic activity whole-mouth saliva (WMS), parotid saliva (PS) and plasma collected contemporaneously from healthy volunteers were analysed by 1H-NMR spectroscopy. Spectra underwent principal component analysis and k-means cluster analysis and metabolite quantification. WMS samples were cultured on both sucrose and peptide-enriched media. Correlation between metabolite concentration and bacterial load was assessed.Results: WMS contained abundant short-chain fatty acids (SCFAs), which were minimal in PS and plasma. WMS spectral exhibited greater inter-individual variation than those of PS or plasma (6.7 and 3.6 fold, respectively), likely reflecting diversity of microbial metabolomes. WMS bacterial load correlated strongly with SCFA levels. Additional WMS metabolites including amines, amino acids and organic acids were positively correlated with bacterial load. Lactate, urea and citrate appeared to enter WMS via PS and the circulation. Urea correlated inversely with WMS bacterial load.Conclusions: Oral microbiota contribute significantly to the WMS metabolome. Several WMS metabolites (lactate, urea and citrate) are derived from the host circulation. WMS may be particularly useful to aid diagnosis of conditions reflective of dysbiosis. WMS could also complement other gastrointestinal fluids in future metabolomic studies.

Highlights

Saliva is an emerging fluid in diagnostic science, offering advantages over fluids more widely used for diagnostic purposes
Aim and methods: To determine the extent to which salivary metabolites reflects host or microbial metabolic activity whole-mouth saliva (WMS), parotid saliva (PS) and plasma collected contemporaneously from healthy volunteers were analysed by 1H-NMR spectroscopy
WMS contained abundant short-chain fatty acids (SCFAs), which were minimal in PS and plasma

Summary

Introduction

Saliva is an emerging fluid in diagnostic science, offering advantages over fluids more widely used for diagnostic purposes. Metabolic profiling of saliva by proton Nuclear Magnetic Resonance spectroscopy (1H-NMR) has revealed discriminatory metabolic signatures for several diseases. These include oral pathologies such as dental caries [9,10], periodontal disease [11,12] and Sjögren’s syndrome [13] as well as extra-oral conditions such as dementia [14] and type 1 diabetes [15]. Aim and methods: To determine the extent to which salivary metabolites reflects host or microbial metabolic activity whole-mouth saliva (WMS), parotid saliva (PS) and plasma collected contemporaneously from healthy volunteers were analysed by 1H-NMR spectroscopy.

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