Prevotella intermedia induces severe bacteremic pneumococcal pneumonia in mice with upregulated platelet-activating factor receptor expression.
Streptococcus pneumoniae is the leading cause of respiratory infection worldwide. Although oral hygiene has been considered a risk factor for developing pneumonia, the relationship between oral bacteria and pneumococcal infection is unknown. In this study, we examined the synergic effects of Prevotella intermedia, a major periodontopathic bacterium, on pneumococcal pneumonia. The synergic effects of the supernatant of P. intermedia (PiSup) on pneumococcal pneumonia were investigated in mice, and the stimulation of pneumococcal adhesion to human alveolar (A549) cells by PiSup was assessed. The effects of PiSup on platelet-activating factor receptor (PAFR) transcript levels in vitro and in vivo were analyzed by quantitative real-time PCR, and the differences between the effects of pneumococcal infection induced by various periodontopathic bacterial species were verified in mice. Mice inoculated with S. pneumoniae plus PiSup exhibited a significantly lower survival rate, higher bacterial loads in the lungs, spleen, and blood, and higher inflammatory cytokine levels in the bronchoalveolar lavage fluid (macrophage inflammatory protein 2 and tumor necrosis factor alpha) than those infected without PiSup. In A549 cells, PiSup increased pneumococcal adhesion and PAFR transcript levels. PiSup also increased lung PAFR transcript levels in mice. Similar effects were not observed in the supernatants of Porphyromonas gingivalis or Fusobacterium nucleatum. Thus, P. intermedia has the potential to induce severe bacteremic pneumococcal pneumonia with enhanced pneumococcal adhesion to lower airway cells.
Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Kentaro
K
Nagaoka
Katsunori
K
Yanagihara
Yoshitomo
Y
Morinaga
Shigeki
S
Nakamura
Tatsuhiko
T
Harada
Hiroo
H
Hasegawa
Koichi
K
Izumikawa
Yuji
Y
Ishimatsu
Hiroshi
H
Kakeya
Masaharu
M
Nishimura
Shigeru
S
Kohno
D000818:Animals; D016470:Bacteremia / Q000382:microbiology / Q000473:pathology*; D001422:Bacterial Adhesion; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology; D016967:Fusobacterium nucleatum / Q000472:pathogenicity; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D056265:Microbial Interactions; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D011018:Pneumonia, Pneumococcal / Q000150:complications* / Q000382:microbiology / Q000473:pathology*; D016966:Porphyromonas gingivalis / Q000472:pathogenicity; D018713:Prevotella intermedia / Q000472:pathogenicity* / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis* / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000472:pathogenicity* / Q000502:physiology; D016019:Survival Analysis; D015854:Up-Regulation
D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor