Metaproteomics Characterizes the Human Gingival Crevicular Fluid Microbiome Function in Periodontitis

Periodontitis is the leading causeof tooth loss in adultsworldwide.The human proteome and metaproteome characterization of periodontitisis not clearly understood. Gingival crevicular fluid samples werecollected from eight periodontitis and eight healthy subjects. Boththe human and microbial proteins were characterized by liquid chromatographycoupled with high-resolution mass spectrometry. A total of 570 humanproteins were found differentially expressed, which were primarilyassociated with inflammatory response, cell death, cellular junction,and fatty acid metabolism. For the metaproteome, 51 genera were identified,and 10 genera were found highly expressed in periodontitis, while11 genera were downregulated. The analysis showed that microbial proteinsrelated to butyrate metabolism were upregulated in periodontitis cases.In particular, correlation analysis showed that the expression ofhost proteins related to inflammatory response, cell death, cellularjunction, and lipid metabolism correlates with the alteration of metaproteins,which reflect the changes of molecular function during the occurrenceof periodontitis. This study showed that the gingival crevicular fluidhuman proteome and metaproteome could reflect the characteristicsof periodontitis. This might benefit the understanding of the periodontitismechanism.