Peroxide tone in nasal exhaled breath condensate after nasal provocation

Aim: The nose—front line of the respiratory tract—is chronically exposed to oxidative stress, leading to reactive oxygen species (ROS)-mediated damage. Aanalyses of exhaled breath condensate (EBC) could provide useful information for possible clinical applications. In this study, we attempted to demonstrate the peroxide tone after nasal provocation by measuring H2O2 in nasal exhaled breath condensate (nEBC). Methods: 5 Healthy subjects and 5 patients with Japanese cedar pollinosis took part in the study after providing informed consent. Using a condenser, EBC were collected by R-tube (Respiratory Research Inc. UK) before and after nasal provocation (15min., 120min.) by nasal pollen as specific antigen and 5% hypertonic saline as nonspecific challenge respectively. H2O2 level was measured by Amplex Red Hydrogen Peroxide/Peroxidase Assay Kit (Thermo Fisher Scientific, MS, USA). All of the studies performed were approved by the Institutional Review Board of Institutions and informed consent was obtained from all of the subjects. Results: Elevation of H2O2 level in nEBC was detected after nasal antigen challenge in the subjects with pollinosis, but not in the non-allergic subjects. On the other hand, after hypertonic saline challenge, H2O2 level in nEBC was elevated both in healthy subjects and patients with pollinosis but it varied. Conclusion: Elevation of H2O2 level in nEBC after nasal provocation was demonstrated. Analysis of H2O2 level with nEBC might be a promising approach to assess the peroxide tone and pathological status of nasal diseases including allergic and non-allergic rhinitis.