<i>Porphyromonas gingivalis</i> Components/Secretions Synergistically Enhance Pneumonia Caused by <i>Streptococcus pneumoniae</i> in Mice
<i>Streptococcus pneumoniae</i> is an important causative organism of respiratory tract infections. Although periodontal bacteria have been shown to influence respiratory infections such as aspiration pneumonia, the synergistic effect of <i>S. pneumoniae</i> and <i>Porp...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-11-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/22/23/12704 |
| Summary: | <i>Streptococcus pneumoniae</i> is an important causative organism of respiratory tract infections. Although periodontal bacteria have been shown to influence respiratory infections such as aspiration pneumonia, the synergistic effect of <i>S. pneumoniae</i> and <i>Porphyromonas gingivalis</i>, a periodontopathic bacterium, on pneumococcal infections is unclear. To investigate whether <i>P. gingivalis</i> accelerates pneumococcal infections, we tested the effects of inoculating <i>P. gingivalis</i> culture supernatant (PgSup) into <i>S. pneumoniae</i>-infected mice. Mice were intratracheally injected with <i>S. pneumoniae</i> and PgSup to induce pneumonia, and lung histopathological sections and the absolute number and frequency of neutrophils and macrophages in the lung were analyzed. Proinflammatory cytokine/chemokine expression was examined by qPCR and ELISA. Inflammatory cell infiltration was observed in <i>S. pneumoniae</i>-infected mice and <i>S. pnemoniae</i> and PgSup mixed-infected mice, and mixed-infected mice showed more pronounced inflammation in lung. The ratios of monocytes/macrophages and neutrophils were not significantly different between the lungs of <i>S. pneumoniae</i>-infected mice and those of mixed-infected mice. PgSup synergistically increased TNF-α expression/production and IL-17 production compared with <i>S. pneumoniae</i> infection alone. We demonstrated that PgSup enhanced inflammation in pneumonia caused by <i>S. pneumoniae</i>, suggesting that virulence factors produced by <i>P. gingivalis</i> are involved in the exacerbation of respiratory tract infections such as aspiration pneumonia. |
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| ISSN: | 1661-6596 1422-0067 |