Salivary microbiome and metabolome analysis of severe early childhood caries

Abstract

BACKGROUND: Severe early childhood caries (SECC) is a bacterial inflammatory disease with complex pathology. Although changes in the oral microbiota and metabolic profile of patients with ECC have been identified, the salivary metabolites and the relationship of host-bacterial interactions with biochemical metabolism remain unclear. We aimed to analyse alterations in the salivary microbiome and metabolome of children with SECC as well as their correlations. Accordingly, we aimed to explore potential salivary biomarkers in order to gain further insight into the pathophysiology of dental caries. Methods: We collected 120 saliva samples from 30 children with SECC and 30 children without caries. The microbial community was identified through 16S ribosomal RNA (rRNA) gene high-throughput sequencing. Additionally, we conducted non-targeted metabolomic analysis through ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry to determine the relative metabolite levels and their correlation with the clinical caries status.RESULTS: There was a significant between-group difference in 8 phyla and 32 genera in the microbiome. Further, metabolomic and enrichment analyses revealed significantly altered 32 salivary metabolites in children with dental caries, which involved pathways such as amino acid metabolism, pyrimidine metabolism, purine metabolism, ATP-binding cassette transporters, and cyclic adenosine monophosphate signalling pathway. Moreover, four in vivo differential metabolites (2-benzylmalate, epinephrine, 2-formaminobenzoylacetate, and 3-Indoleacrylic acid) might be jointly applied as biomarkers (area under the curve = 0.734). Furthermore, the caries status was correlated with microorganisms and metabolites. Additionally, Spearman's correlation analysis of differential microorganisms and metabolites revealed that Veillonella, Staphylococcus, Neisseria, and Porphyromonas were closely associated with differential metabolites.Conclusion: This study identified different microbial communities and metabolic profiles in saliva, which may be closely related to caries status. Our findings could inform future strategies for personalized caries prevention, detection, and treatment.

Heat Sink Equivalent Thermal Test Method and Its Application in Low-Orbit Satellites

“…With the diversification of satellites, it is no longer feasible to simplify the tests according to different types of satellites [15], and a universal, simplified test method must be proposed. A new method without test cutting called the heat sink equivalent thermal test method, which uses the heat sink of vacuum test equipment to complete the heat flow simulation, achieves the goal of reducing costs and shortening the thermal test duration under the premise of ensuring the reliability of the satellite.…”