[ODP25] 5. Pathogenicity -e. Infection models

[ODP-157] P. gingivalis components/secretions synergistically enhance pneumonia caused by S. pneumonia

Teppei Okabe¹, Yosuke Kamiya¹, Takeshi Kikuchi¹, Masayuki Umemura², Yoshihiko Sugita³, Yoshikazu Naiki⁴, Yoshiaki Hasegawa⁴, Jun-ichiro Hayashi¹, Naoya Higuchi⁵, Akio Mitani¹ (¹Dept. Periodontol., Sch. Dent., Aichi Gakuin Univ., ²Mol. Microbiol. Gr., TBRC, Univ. Ryukyus, ³Dept. Oral Pathol., Sch. Dent., Aichi Gakuin Univ., ⁴Dept. Microbiol., Sch. Dent., Aichi Gakuin Univ., ⁵Dept. Endod., Sch. Dent., Aichi Gakuin Univ.)

Streptococcus pneumonia (Sp) is the main pathogens causing pneumonia. Although periodontal bacteria have been shown to influence respiratory infections such as aspiration pneumonia, the synergistic effect of Sp and Porphyromonas gingivalis (Pg), a periodontopathic bacterium, on pneumococcal infections is unclear. To investigate whether Pg accelerates pneumococcal infections, we tested the effect of inoculating Pg culture supernatant (PgSup) into Sp-infected mice. Mice were intratracheally injected with Sp and PgSup to induce pneumonia, the frequency of neutrophils and macrophages in the lung and proinflammatory cytokines/chemokines expressions were examined. Inflammatory cell infiltration was observed in Sp-injected mice and Sp and PgSup mixed-injected mice, and mixed-injected mice showed more pronounced inflammation in the lungs. The ratios of monocytes/macrophages and neutrophils were slightly higher in the lungs of mixed-injected mice than those in Sp-injected mice. PgSup synergistically increased expression/production of IL-1β, TNF-α, KC, MIP-2, and IL-17A compared with Sp injection alone. We demonstrated that PgSup enhanced inflammation in pneumonia caused by Sp, suggesting that virulence factors produced by Pg are involved in the exacerbation of respiratory tract infections such as aspiration pneumonia.