Membrane Vesicles of <i>Enterococcus faecalis</i>: In Vitro Composition Analysis and Macrophage Inflammatory Response Under Different pH Conditions
<i>Enterococcus faecalis</i> (<i>E. faecalis</i>) is one of the most detected bacteria in persistent apical periodontitis (PAP), with alkaline tolerance enabling post-treatment survival. In this study, we will investigate how alkaline conditions alter proteomic and metabolomi...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/13/6/1344 |
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| Summary: | <i>Enterococcus faecalis</i> (<i>E. faecalis</i>) is one of the most detected bacteria in persistent apical periodontitis (PAP), with alkaline tolerance enabling post-treatment survival. In this study, we will investigate how alkaline conditions alter proteomic and metabolomic profiles of <i>E. faecalis</i> membrane vesicles (MVs) and preliminarily investigate the role of MVs of <i>E. faecalis</i> in the regulation of macrophage inflammatory response. <i>E. faecalis</i> MVs were characterized using transmission electron microscopy and nanoparticle tracking analysis under varying pH conditions. MVs’ proteomic and metabolomic profiling across pH levels was compared. The effects of <i>E. faecalis</i> MVs on human dTHP-1 macrophages were evaluated using CCK-8 metabolic activity assays and ELISA-based quantitative analysis of inflammatory cytokines. In this study, the presence of <i>E. faecalis</i> MVs was verified, and the alkaline environment of pH 9.0 did not alter their production. Through proteomic and metabolomic analysis, we observed that ATP synthase and stress proteins, as well as lysine degradation and tryptophan metabolism pathways, were significantly enriched in the MVs at pH 9.0. Finally, we observed that both <i>E. faecalis</i> MVs at pH 7.0 and pH 9.0 could dose-dependently inhibit the activity of dTHP-1 cells. <i>E. faecalis</i> MVs promote the secretion of IL-6, TNF-α, IL-1β, IL-1ra, and TGF-β by macrophages. Compared to pH 7.0, pH 9.0 <i>E. faecalis</i> MVs have a reduced effect on IL-1ra and TGF-β secretion. Additionally, we observed a significant increase in the IL-1β/IL-1ra ratio after treatment with <i>E. faecalis</i> MVs. Our study indicated that <i>E. faecalis</i> can produce MVs in pH 7.0 and pH 9.0 environments. ATP synthase, stress proteins, as well as lysine degradation and tryptophan metabolism pathways, were significantly enriched in pH 9.0 MVs. Furthermore, <i>E. faecalis</i> MVs could promote inflammatory responses in macrophages and dose-dependently inhibit the viability of dTHP-1 cells. |
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| ISSN: | 2076-2607 |