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

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• 作者：Naseem Mushtaq PhD^a ; Majid Ezzati PhD^c ; Lucinda Hall PhD^a ; Iain Dickson BSc^a ; Michael Kirwan PhD^a ; Ken M.Y. Png PhD^b ; Ian S. Mudway PhD^d ; Jonathan Grigg MD ; FRCPCH^a ; ^{j.grigg@qmul.ac.uk"" rel=""nofollow}
• 关键词：Urban particulate matter ; Streptococcus pneumoniae ; adhesion ; A549 ; primary human bronchial epithelial cells
• 刊名：Journal of Allergy and Clinical Immunology
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：127
• 期：5
• 页码：1236-1242.e2
• 全文大小：691 K

文摘

Background

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.

Objectives

To define whether inhalable urban PM enhances the adhesion of S pneumoniae to airway epithelial cells.

Methods

A549 cells were cultured with PM₁₀ from Leicester (United Kingdom [UK]) and PM₁₀ and PM less than 2.5 μm in aerodynamic diameter (PM_2.5) 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.

Results

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.

Conclusion

Urban PM increases adhesion of S pneumoniae to human airway epithelial cells. PM-stimulated adhesion is mediated by oxidative stress and PAFR.