The nose is the gateway to the soul… or the lungs at least… making it an important point of first contact between our fragile bodies and the hordes of superbugs attempting to take over the world. Only the brave immunologist has the power to save us from this dire threat. While it’s been known for a few years now that the inflammatory cytokine IL-17A is key to the control of many respiratory infections, no-one has been able to provide any information on the source of this cytokine in nasal infections or how this production is regulated. No more!

Post-doctoral fellow Chris Verschoor and Ph.D. Candidate Mike Dorrington, both trainees in Dr. Dawn Bowdish’s lab have recently had their manuscript “MicroRNA-155 is required for the clearance of Streptococcus pneumoniae from the nasopharynx” accepted for publication in Infection & Immunity. The paper, which was produced in collaboration with Dr. Param Nair of the Firestone Institute, outlines how microRNA- (miR-)155 regulates the immune response to S. pneumoniae colonization in the nasal passages of mice by stimulating the differentiation of Th17 cells. These cells then produce large amounts of IL-17A, which then acts as a chemotactic agent for macrophages, which have awesome swords and stuff that kill the bacteria and save the world! (macrophages are the best cells, by the way)

This paper is the first to show a direct connection between IL-17A-producing T cells and the clearance of a bacterial pathogen from the nasopharynx. It is also the first to show a phenotype of IL-17A deficiency without completely knocking out the cytokine itself. It represents a significant step forward in understanding the regulation of intranasal immune responses to bacterial colonization and how innate and adaptive immune networks collaborate in clearing these events. Way to go Bowdish Lab!

For more information please visit www.bowdish.ca/lab and check out the paper in an upcoming edition of Infection & Immunity.