Adhesion of Streptococcus Pneumoniae to Human Airway Epithelial Cells Exposed to Urban Particulate Matter

From: ScienceDirect.com

http://www.sciencedirect.com/science/article/pii/S0091674910018609

Journal of Allergy and Clinical Immunology
Volume 127, Issue 5, May 2011, Pages 1236-1242.

Adhesion of Streptococcus pneumoniae to human airway epithelial cells exposed to urban particulate matter

Naseem Mushtaq PhD, Majid Ezzati PhD, Lucinda Hall PhD, Iain Dickson BSc, Michael Kirwan PhD, Ken M.Y. Png PhD, Ian S. Mudway PhD, and Jonathan Grigg MD, FRCPCH

The authors  give the background for their study: “Epidemiologic studies report an association between pneumonia and urban particulate matter (PM) less than 10 microns (μm) in aerodynamic diameter (PM₁₀). Streptococcus pneumoniae is a common cause of bacterial pneumonia worldwide. To date, the mechanism whereby urban PM enhances vulnerability to S pneumoniae infection is unclear. Adhesion of S pneumoniae to host cells is a prerequisite for infection. Host-expressed proteins, including the receptor for platelet-activating factor (PAFR), are co-opted by S pneumoniae to adhere to lower airway epithelial cells.”

The results of the study were as follows: “PM₁₀ (UK) increased S pneumoniae adhesion to both A549 airway epithelial cells and human primary bronchial epithelial cells. PM₁₀ (Ghana) and PM_2.5 (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.”

The authors conclude, “Urban PM increases adhesion of S pneumoniae to human airway epithelial cells. PM-stimulated adhesion is mediated by oxidative stress and PAFR [platelet activating factor receptor].”