<i>Porphyromonas gingivalis</i> enhances pneumococcal adhesion to human alveolar epithelial cells by increasing expression of host platelet‐activating factor receptor

Streptococcus pneumoniae causes pneumonia by infecting the alveolar epithelium via binding to host receptors, such as platelet-activating factor receptor (PAFR). Although chronic periodontitis has been identified a risk factor, how periodontopathic bacteria cause is not known. We found that S. adhered PAFR expressed on A549 human epithelial cells stimulated Porphyromonas gingivalis culture supernatant, and this was abrogated PAFR-specific inhibitor. Among major virulence factors of P. (lipopolysaccharide, fimbriae gingipains [Rgps Kgp]), expression pneumococcal adhesion were executed in an Rgp-dependent manner. Lipopolysaccharide did induce expression. Hence, our findings suggest enhances alveoli inducing are responsible for this.