RT Journal Article
SR Electronic
T1 Bacterial DNA amplifies neutrophilic inflammation in IL-17-exposed airways
JF ERJ Open Research
JO erjor
FD European Respiratory Society
SP 00474-2022
DO 10.1183/23120541.00474-2022
VO 9
IS 1
A1 Nastaran Mues
A1 Richard J. Martin
A1 Rafeul Alam
A1 Niccolette Schaunaman
A1 Kris Genelyn Dimasuay
A1 Christena Kolakowski
A1 Clyde J. Wright
A1 Lijun Zheng
A1 Hong Wei Chu
YR 2023
UL http://openres.ersjournals.com/content/9/1/00474-2022.abstract
AB Background Neutrophilic asthma (NA) is associated with increased airway interleukin (IL)-17 and abnormal bacterial community such as dominance of nontypeable Haemophilus influenzae (NTHi), particularly during asthma exacerbations. Bacteria release various products including DNA, but whether they cooperate with IL-17 in exaggerating neutrophilic inflammation is unclear. We sought to investigate the role of bacteria-derived DNA in airway neutrophilic inflammation related to IL-17-high asthma and underlying mechanisms (e.g. Toll-like receptor 9 (TLR9)/IL-36γ signalling axis).Methods Bacterial DNA, IL-8 and IL-36γ were measured in bronchoalveolar lavage fluid (BALF) of people with asthma and healthy subjects. The role of co-exposure to IL-17 and bacterial DNA or live bacteria in neutrophilic inflammation, and the contribution of the TLR9/IL-36γ signalling axis, were determined in cultured primary human airway epithelial cells and alveolar macrophages, and mouse models.Results Bacterial DNA levels were increased in asthma BALF, which positively correlated with IL-8 and neutrophil levels. Moreover, IL-36γ increased in BALF of NA patients. Bacterial DNA or NTHi infection under an IL-17-high setting amplified IL-8 production and mouse lung neutrophilic inflammation. DNase I treatment in IL-17-exposed and NTHi-infected mouse lungs reduced neutrophilic inflammation. Mechanistically, bacterial DNA-mediated amplification of neutrophilic inflammation is in part dependent on the TLR9/IL-36γ signalling axis.Conclusions Bacterial DNA amplifies airway neutrophilic inflammation in an IL-17-high setting partly through the TLR9 and IL-36γ signalling axis. Our novel findings may offer several potential therapeutic targets including TLR9 antagonists, IL-36γ neutralising antibodies and DNase I to reduce asthma severity associated with exaggerated airway neutrophilic inflammation.More bacterial DNA was found in airways of asthmatics with neutrophilic inflammation. Bacterial DNA along with IL-17 amplified neutrophil chemokine production and airway neutrophil influx, which was reduced by an IL-36γ neutralising antibody or DNase I. https://bit.ly/3k9zkj4