RT Journal Article
SR Electronic
T1 Neutrophils drive alveolar macrophage IL-1β release during respiratory viral infection
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP thoraxjnl-2017-210010
DO 10.1136/thoraxjnl-2017-210010
A1 Teresa Peiró
A1 Dhiren F Patel
A1 Samia Akthar
A1 Lisa G Gregory
A1 Chloe J Pyle
A1 James A Harker
A1 Mark A Birrell
A1 Clare M Lloyd
A1 Robert J Snelgrove
YR 2017
UL http://thorax.bmj.com/content/early/2017/10/27/thoraxjnl-2017-210010.abstract
AB Background Alveolar macrophages are sentinels of the airways that must exhibit immune restraint to innocuous antigens but elicit a robust inflammatory response to pathogenic threats. How distinction between these dichotomous functions is controlled is poorly defined.Neutrophils are the first responders to infection, and we hypothesised that they may free alveolar macrophages from their hyporesponsive state, promoting their activation. Activation of the inflammasome and interleukin (IL)-1β release is a key early inflammatory event that must be tightly regulated. Thus, the role of neutrophils in defining inflammasome activation in the alveolar macrophage was assessed.Methods Mice were infected with the X31 strain of influenza virus and the role of neutrophils in alveolar macrophage activation established through administration of a neutrophil-depleting (1A8) antibody.Results Influenza elicited a robust IL-1β release that correlated (r=0.6849; p<0.001) with neutrophil infiltrate and was ablated by neutrophil depletion. Alveolar macrophages were shown to be the prominent source of IL-1β during influenza infection, and virus triggered the expression of Nod-like receptor protein 3 (NLRP3) inflammasome and pro-IL-1β in these cells. However, subsequent activation of the inflammasome complex and release of mature IL-1β from alveolar macrophages were critically dependent on the provision of a secondary signal, in the form of antimicrobial peptide mCRAMP, from infiltrating neutrophils.Conclusions Neutrophils are critical for the activation of the NLRP3 inflammasome in alveolar macrophages during respiratory viral infection. Accordingly, we rationalise that neutrophils are recruited to the lung to confront a viable pathogenic threat and subsequently commit alveolar macrophages to a pro-inflammatory phenotype to combat infection.