To define whether inhalable urban PM enhances the adhesion of S pneumoniae to airway epithelial cells.
A549 cells were cultured with PM10 from Leicester (United Kingdom [UK]) and PM10 and PM less than 2.5 μm in aerodynamic diameter (PM2.5) from Accra (Ghana), then infected with S pneumoniae strain D39. Pneumococcal adhesion to human primary bronchial epithelial cells was also assessed. Bacterial adhesion was determined by quantitative culture and confocal microscopy. The role of oxidative stress was assessed by N-acetyl cysteine, and the role of PAFR was assessed by mRNA transcript level, receptor expression, and receptor blocking.
PM10 (UK) increased S pneumoniae adhesion to both A549 airway epithelial cells and human primary bronchial epithelial cells. PM10 (Ghana) and PM2.5 (Ghana) also increased adhesion. Culture of A549 cells by PM10 (UK) increased PAFR mRNA transcript level and PAFR expression. PM10 (UK)–stimulated adhesion to A549 cells was attenuated by a PAFR blocker and N-acetyl cysteine.
Urban PM increases adhesion of S pneumoniae to human airway epithelial cells. PM-stimulated adhesion is mediated by oxidative stress and PAFR.