The role of air pollution and bacteria in COPD

Air pollution is the single largest environmental health risk worldwide. Particulate matter (PM) air pollution is released as a result of fossil fuel combustion and vehicle motion, breaking and tyre wear. It has been shown that exposure to PM can cause increased levels of respiratory disease, including the exacerbation of COPD, which is frequently associated with bacterial infection. Despite this, the effects of air pollution exposure on COPD associated respiratory bacteria, includingHaemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae are largely unknown. Our recent publication was the first to document that as well as damaging the host, PM has a direct impact on bacteria that can cause respiratory infections. We showed that exposure to black carbon (BC), an important component of PM, results in alterations in biofilm structure in both Streptococcus pneumoniae and Staphylococcus aureus, and increases dissemination of colonising S. pneumoniaein in vivo models.

Following on from this work, we aim to determine how BC impacts the growth, behaviour and virulence of bacteria associated with the COPD exacerbation, including non-typeable Haemophilus influenzaeand Moraxella catarrhalis. Current data show that BC exposure is decreasing the biofilm forming ability of NTHistrains 162 and 375. M. catarrhalis strain M61 biofilm formation is also decreased in the presence of BC, while its growth rate is increased. In addition, pre-exposing NTHi375 cells to BC, prior to infection of A549 cells, increases their ability to adhere to human epithelial cells. This suggests that the frequency of bacterial infection induced COPD exacerbation may be altered in patients from highly polluted areas.