Salivary Extracellular Vesicles from Host, Bacteria and Fungus as Nanomessengers Reflecting Host−Microbiome Interaction in Periodontal Inflammation

Abstract

Extracellular vesicles (EVs) secreted by the host and polymicrobial oral community are natural endogenous biological nanoparticles that mediate host-microbe interactions. Given their abundance in biofluids, host, fungal and bacterial EVs circulating in saliva may reflect periodontitis-associated microbial dysbiosis and inflammation. In this study, salivary EVs from 20 healthy controls and 57 stages III/IV periodontitis were isolated using a dual strategy: immunoaffinity to isolate host EVs for cytokine profiling, followed by size-exclusion chromatography (SEC) to enrich non-host (microbial) EVs for 16S rRNA and fungal ITS sequencing. In periodontitis, we observed a significant increase in CD49e+ and CD105+ host EV subpopulations and elevated host EV-associated cytokines of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and granulocyte-macrophage colony-stimulating factor (GM-CSF), indicating an enhanced inflammatory host-EV profile. 16s rRNA sequencing of non-host microbial EV-DNA profiling revealed enrichment of bacterial EVs (BEVs), including genera Porphyromonas, Treponema, Filifactor, and Tannerella, with species of Porphyromonas gingivalis, Filifactor alocis, Tannerella forsythia, Treponema denticola, and Treponema socranskii. In contrast, commensal genera BEVs (Neisseria, Haemophilus) and fungal EVs from Malassezia globosa were enriched in health. Fungal EVs from Candida albicans and M. arunalokeiwere also elevated in disease. Combined host-EVs-IL-9 and T. forsythia-BEVs achieved an AUC of 0.989, increasing to 0.992 with the addition of F. alocis-BEVs, outperforming individual markers (AUC = 0.85-0.91). Pooled periodontitis microbial EVs (10 µg/mL) induced a proinflammatory response in the oral keratinocytes (OKFs) after 24 h, with increased IL-6 and IL-8 cytokines, and upregulated mRNA expression of C-C motif chemokine ligand 2 (CCL2), IL-1β, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) compared with the no-EV control. Our findings demonstrated that salivary host-, bacterial-, and fungal-derived salivary EVs act as natural nanomessengers reflecting host-microbiome interactions and represent promising non-invasive candidate biomarkers of periodontitis.