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Porphyromonas gingivalis Outer Membrane Vesicles Stimulate Gingival Epithelial Cells to Induce Pro-Inflammatory
Yuta Uemura1, Yuka Hiroshima2, Ayano Tada3
1Department of Periodontology and Endodontology, Graduate School of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8504, Japan.
Abstract:
Porphyromonas gingivalis (Pg) is a keystone pathogen associated with chronic periodontitis and produces outer membrane vesicles (OMVs) that contain lipopolysaccharide (LPS), gingipains, and pathogen-derived DNA and RNA. Pg-OMVs are involved in the pathogenesis of periodontitis. Pg-OMV-activated pathways that induce the production of the pro-inflammatory cytokines, interleukin (IL)-6, and IL-8 in the human gingival epithelial cell line, OBA-9, were investigated. The role of mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB in levels of Pg-OMV-induced pro-inflammatory cytokines was investigated using Western blot analysis and specific pathway inhibitors. Pg-OMVs induced IL-6 and IL-8 production via the extracellular signal-regulated kinase (Erk) 1/2, c-Jun N-terminal kinase (JNK), p38 MAPK, and NF-κB signaling pathways in OBA-9 cells. In addition, the stimulator of interferon genes (STING), an essential innate immune signaling molecule, was triggered by a cytosolic pathogen DNA. Pg-OMV-induced IL-6 and IL-8 mRNA expression and production were significantly suppressed by STING-specific small interfering RNA. Taken together, these results demonstrated that Pg-OMV-activated Erk1/2, JNK, p38 MAPK, STING, and NF-κB signaling pathways resulting in increased IL-6 and IL-8 expression in human gingival epithelial cells. These results suggest that Pg-OMVs may play important roles in periodontitis exacerbation by stimulating various pathways.
Insights
Porphyromonas gingivalis outer membrane vesicles (OMVs) activate key inflammatory pathways, including MAPK, NF-κB, and STING. These pathways drive interleukin-6 and -8 production, contributing to periodontitis exacerbation.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Porphyromonas gingivalis (Pg) is a keystone pathogen in chronic periodontitis.
- Pg produces outer membrane vesicles (OMVs) containing virulence factors like LPS, gingipains, and nucleic acids.
- Pg-OMVs are implicated in periodontitis pathogenesis.
Purpose of the Study:
- To investigate the signaling pathways activated by Pg-OMVs in human gingival epithelial cells (OBA-9).
- To determine the role of MAPK and NF-κB pathways in Pg-OMV-induced cytokine production.
- To explore the involvement of the stimulator of interferon genes (STING) pathway.
Main Methods:
- Western blot analysis was used to assess protein activation.
- Specific pathway inhibitors were employed to dissect signaling cascades.
- STING-specific small interfering RNA (siRNA) was used to silence STING expression.
Main Results:
- Pg-OMVs induced the production of pro-inflammatory cytokines IL-6 and IL-8.
- Activation of extracellular signal-regulated kinase (Erk) 1/2, c-Jun N-terminal kinase (JNK), p38 MAPK, and NF-κB pathways was observed.
- STING was triggered by cytosolic DNA within Pg-OMVs, and STING inhibition significantly reduced IL-6 and IL-8 expression.
Conclusions:
- Pg-OMVs activate Erk1/2, JNK, p38 MAPK, STING, and NF-κB signaling pathways in gingival epithelial cells.
- These activated pathways lead to increased expression of IL-6 and IL-8.
- Pg-OMVs likely contribute to periodontitis exacerbation through the stimulation of these inflammatory pathways.
