Publications & Reports

Nontypeable Haemophilus influenzae induces sustained lung oxidative stress and protease expression.

Paul T King, Roleen Sharma, Kim O'Sullivan, Stavros Selemidis, Steven Lim, Naghmeh Radhakrishna, Camden Lo, Jyotika Prasad, Judy Callaghan, Peter McLaughlin, Michael Farmer, Daniel Steinfort, Barton Jennings, James Ngui, Bradley R S Broughton, Belinda Thomas, Ama-Tawiah Essilfie, Michael Hickey, Peter W Holmes, Philip Hansbro, Philip G Bardin, Stephen R Holdsworth
Monash University Department of Medicine/Monash Medical Centre, Melbourne, Australia; Monash Lung and Sleep, Monash Medical Centre, Melbourne, Australia.

Abstract

Nontypeable Haemophilus influenzae (NTHi) is a prevalent bacterium found in a variety of chronic respiratory diseases. The role of this bacterium in the pathogenesis of lung inflammation is not well defined. In this study we examined the effect of NTHi on two important lung inflammatory processes 1), oxidative stress and 2), protease expression. Bronchoalveolar macrophages were obtained from 121 human subjects, blood neutrophils from 15 subjects, and human-lung fibroblast and epithelial cell lines from 16 subjects. Cells were stimulated with NTHi to measure the effect on reactive oxygen species (ROS) production and extracellular trap formation. We also measured the production of the oxidant, 3-nitrotyrosine (3-NT) in the lungs of mice infected with this bacterium. NTHi induced widespread production of 3-NT in mouse lungs. This bacterium induced significantly increased ROS production in human fibroblasts, epithelial cells, macrophages and neutrophils; with the highest levels in the phagocytic cells. In human macrophages NTHi caused a sustained, extracellular production of ROS that increased over time. The production of ROS was associated with the formation of macrophage extracellular trap-like structures which co-expressed the protease metalloproteinase-12. The formation of the macrophage extracellular trap-like structures was markedly inhibited by the addition of DNase. In this study we have demonstrated that NTHi induces lung oxidative stress with macrophage extracellular trap formation and associated protease expression. DNase inhibited the formation of extracellular traps.

Publication

  • Journal: PloS One
  • Published: 20/03/2015
  • Volume: 10
  • Issue: 3
  • Pagination: e0120371