S‐Nitrosoglutathione Reductase Inhibition Attenuates Airway Hyperreactivity in a Neonatal Hyperoxia‐Exposed Mouse Model

Abstract

Premature infants exposed to supplemental oxygen are at risk for developing wheezing disorders and airway hyperreactivity (AHR). We have previously shown that the endogenous smooth muscle relaxant molecule, S‐nitrosoglutathione (GSNO), is degraded in neonatal hyperoxia by upregulated GSNO reductase (GSNOR) in the murine lung (Raffay, et al. Molecular Pharmacology 2016; 90(4):418–26). We hypothesize that inhibition or deletion of GSNOR will attenuate hyperoxia‐induced AHR in this neonatal mouse model. Newborn C57BL/6 wild‐type (background) or GSNOR−/− (knockout) mice were randomized on the first day of life and assigned to room air (21% O2) or hyperoxic (60% O2) groups for three weeks. At day P21, AHR was assessed in vitro using precision‐cut living lung slice preparations in response to increasing doses of bath‐applied methacholine (MCh, 0.25–64 μM). Wild‐type lung slices were pre‐incubated overnight with or without a GSNOR inhibitor (100 μM N6022). AHR is reported as percent change in airway lumen area from baseline (±SEM). 2–3 airways were imaged and averaged per animal per condition. Neonatal hyperoxia significantly increased (p<0.001) airway contractile responses to MCh in wild‐type mice with a mean maximal effect (Emax) of 70.4 ± 2.1% compared to the room air control Emax of 44.5 ± 9.1%. GSNOR inhibition significantly reduced airway contractile responses in wild‐type hyperoxic slices to 34.1 ± 4.2% (p<0.001). GSNOR−/− mice exposed to hyperoxia did not display increased airway contractile responses (Emax= 50.9 ± 5.5%). These studies show that neonatal hyperoxia‐exposed mice display in vitro AHR to methacholine and that inhibition or deletion of GSNOR attenuates hyperoxia‐induced AHR. We speculate that increased lung GSNOR expression is critical for neonatal hyperoxic bronchoconstriction. GSNO‐based therapies may serve as novel treatments for premature patients with AHR.Support or Funding InformationSupported by NIH 5K08HL133459‐02 and ATS Foundation Unrestricted Research GrantThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.