S‐Nitrosoglutathione Reductase Inhibition Attenuates Long Term Effects of Neonatal Hyperoxia on Airway Hyperreactivity

Abstract

Bronchopulmonary dysplasia survivors display long‐term obstructive lung disease with airway hyperreactivity (AHR). While often treated with asthma medications, patient responses are variable. 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 of GSNOR is a novel approach to attenuate neonatal hyperoxia‐induced AHR in room air recovered mice. Newborn C57BL/6 mice were randomized on the first day of life and assigned to room air (21% O2) or hyperoxic (60% O2) groups for three weeks to induce bronchopulmonary dysplasia AHR. Animals were then recovered in room air until six weeks of age. 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). Lung slices were pre‐incubated with or without a GSNOR inhibitor (100 μM N6022) or a β2 adrenergic receptor agonist (10 or 100 μM levalbuterol). 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 airway contractile responses to MCh in room air recovered mice with a mean maximal effect (Emax) of 71.9 ± 2.7% change from baseline compared to the room air control Emax of 39.8 ± 5.2% (p<0.01). GSNOR inhibition significantly attenuated hyperoxic effects on AHR (32.2 ± 2.0%, p<0.001). Pre‐incubation of hyperoxic slices with either a GSNOR inhibitor or a β2 adrenergic receptor agonist (100 μM) also attenuated the response to the maximal dose of MCh (64 μM) compared to vehicle (both p<0.01). These studies show that neonatal hyperoxia‐exposed mice display longer‐term in vitro AHR to MCh and that inhibition of GSNOR reverses hyperoxia‐induced AHR comparable to a β2 adrenergic receptor agonist. We speculate that GSNO‐based therapies may serve as novel treatments for AHR in bronchopulmonary dysplasia survivors that do not respond to β2 adrenergic receptor agonists.Support or Funding InformationSupported by NIH 5K08HL133459‐03 and ATS Research Foundation Unrestricted Critical Care Grant