Abstract
Streptococcus pneumoniae causes pneumonia by infecting the alveolar epithelium via binding to host receptors, such as the platelet-activating factor receptor (PAFR). Although chronic periodontitis has been identified as a pneumonia risk factor, how periodontopathic bacteria cause pneumonia is not known. We found that S. pneumoniae adhered to PAFR expressed on A549 human alveolar epithelial cells stimulated by Porphyromonas gingivalis culture supernatant, and this was abrogated by a PAFR-specific inhibitor. Among the major virulence factors of P. gingivalis [lipopolysaccharide (LPS), fimbriae and gingipains (Rgps and Kgp)], PAFR expression and pneumococcal adhesion were executed in an Rgp-dependent manner. LPS and fimbriae did not induce PAFR expression. Hence, our findings suggest that P. gingivalis enhances pneumococcal adhesion to human alveoli by inducing PAFR expression and that gingipains are responsible for this.
Keywords:
Porphyromonas gingivalis; Streptococcus pneumoniae; PAFR; adhesion; alveoli; gingipain; lung; platelet-activating factor receptor; pneumonia.
© 2021 Federation of European Biochemical Societies.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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A549 Cells
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Bacterial Adhesion / drug effects
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Coculture Techniques
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Culture Media, Conditioned / chemistry
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Culture Media, Conditioned / pharmacology
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Fimbriae, Bacterial / chemistry
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Gene Expression Regulation
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Gingipain Cysteine Endopeptidases / deficiency
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Gingipain Cysteine Endopeptidases / genetics
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Gingipain Cysteine Endopeptidases / pharmacology*
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Host-Pathogen Interactions / genetics
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Humans
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Lipopolysaccharides / pharmacology
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Models, Biological
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Platelet Membrane Glycoproteins / agonists
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Platelet Membrane Glycoproteins / genetics*
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Platelet Membrane Glycoproteins / metabolism
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Porphyromonas gingivalis / genetics
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Porphyromonas gingivalis / metabolism*
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Porphyromonas gingivalis / pathogenicity
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Pulmonary Alveoli / microbiology
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RNA, Messenger / agonists
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RNA, Messenger / genetics*
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RNA, Messenger / metabolism
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Receptors, G-Protein-Coupled / agonists
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Receptors, G-Protein-Coupled / genetics*
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Receptors, G-Protein-Coupled / metabolism
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Virulence Factors / deficiency
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Virulence Factors / genetics
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Virulence Factors / pharmacology*
Substances
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Culture Media, Conditioned
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Gingipain Cysteine Endopeptidases
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Lipopolysaccharides
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Platelet Membrane Glycoproteins
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RNA, Messenger
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Receptors, G-Protein-Coupled
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Virulence Factors
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platelet activating factor receptor