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Updated: Jul 14, 2026
Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages
Published on: February 22, 2017
Membrane Vesicles of Enterococcus faecalis: In Vitro Composition Analysis and Macrophage Inflammatory Response Under
Zijian Yuan1, Wenling Huang1, Poukei Chan1
1Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510055, China.
Abstract:
Enterococcus faecalis (E. faecalis) 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 E. faecalis membrane vesicles (MVs) and preliminarily investigate the role of MVs of E. faecalis in the regulation of macrophage inflammatory response. E. faecalis 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 E. faecalis 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 E. faecalis 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 E. faecalis MVs at pH 7.0 and pH 9.0 could dose-dependently inhibit the activity of dTHP-1 cells. E. faecalis 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 E. faecalis 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 E. faecalis MVs. Our study indicated that E. faecalis 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, E. faecalis MVs could promote inflammatory responses in macrophages and dose-dependently inhibit the viability of dTHP-1 cells.
