Abstract
RATIONALE: S-Nitrosothiols (SNO) inhibit immune activation of the respiratory epithelium and airway SNO levels are decreased in inflammatory lung disease. Ethyl nitrite (ENO) is a gas with chemical properties favoring SNO formation. Augmentation of airway SNO by inhaled ENO treatment may decrease lung inflammation and subsequent injury by inhibiting activation of the airway epithelium. OBJECTIVES: To determine the effect of inhaled ENO on airway SNO levels and LPS-induced lung inflammation/injury. METHODS: Mice were treated overnight with inhaled ENO (10 ppm) or air, followed immediately by exposure to aerosolized LPS or saline. Parameters of inflammation and lung injury were quantified 1 hour after completion of the aerosol exposure and correlated to lung airway and tissue SNO levels. MEASUREMENTS AND MAIN RESULTS: Aerosolized LPS induced a decrease in airway and lung tissue SNO levels including S-nitrosylated NF-kappaB. The decrease in lung SNO was associated with an increase in lung NF-kappaB activity, cytokine/chemokine expression (keratinocyte-derived chemokine, tumor necrosis factor-alpha, and IL-6), airway neutrophil influx, and worsened lung compliance. Pretreatment with inhaled ENO restored airway SNO levels and reduced LPS-mediated NF-kappaB activation thereby inhibiting the downstream inflammatory response and preserving lung compliance. CONCLUSIONS: Airway SNO serves an antiinflammatory role in the lung. Inhaled ENO can be used to augment airway SNO and protect from LPS-induced acute lung injury.