Effect of Inhaled Glutathione on Airway Response to ‘ Fog ’ Challenge in Asthmatic Patients
Objective: We report on the effect of glutathione, an antioxidant compound on the airway response to the ultrasonically nebulised distilled water (UNDW, ‘fog’) challenge. Methods: 12 subjects with mild-to-moderate bronchial asthma underwent double-blind, cross-over pretreatment, administered 30 min earlier, in a randomised order with inhaled glutathione (G) (600 mg), sodium cromoglycate (SCG) (20 mg) and placebo (P), followed by the challenge. Results: After P pretreatment UNDW challenge caused a mean 20.41% decrease in FEV-1 (p ! 0.05), after G, a mean 6.04% fall in FEV-1 (p = n.s.), and after SCG a mean 5.99% fall in FEV-1 (p = n.s.). Conclusions: G significantly attenuated ‘fog’-induced falls in FEV-1 (p ! 0.001 compared with P) and showed a protective effect on UNDW-induced bronchoconstriction. Copyright © 1999 S. Karger AG, Basel Introduction It has been demonstrated that reactive oxygen species (ROS) generated by several inflammatory cells participate in airway inflammation and their production is increased in bronchial asthma [1]. Many antioxidants are contained in the lung playing an essential role in minimizing or preventing the adverse effects of ROS [2]. Glutathione, a sulphydryl-containing tripeptide produced by most mammalian cells, is an efficient scavenger of ROS and is found in high concentrations in the lung epithelial lining fluid (ELF) [3]. As ROS may produce many of the pathophysiologic changes associated with asthma, the increased antioxidant defences may balance the oxidant generation. BAL fluid GSH concentrations are increased in patients with mild asthma and correlate with airway reactivity [4]. The development of nocturnal airway obstruction in asthma was associated with enhanced production of oxygen radicals by air-space cells [5]. Enhancement of reactive oxygen species formation by polymorphonuclear neutrophils and monocytes was observed in subjects with stable asthma [6]. Mast cells lying in the surface mucosa of the Baseline Fev-1, liters Inhaled Glutathione and Fog Challenge Respiration 1999;66:518–521 519 Table 1. Baseline FEV-1, prechallenge FEV-1 and maximum falls in FEV-1 in the 12 subjects studied, on the prestudy screening day and after pretreatment with G, SCG or P (mean B 1 SD) Prestudy Placebo G SCG 3.18 (0.7) 3.12 (0.8) 3.16 (0.9) Prechallenge Fev-1, liters 3.19 (0.9) 3.23 (0.59) 3.18 (0.50) 3.16 (0.45) Maximum % fall in Fev-1, liters –20.8 –20.41 –6.04* –5.99* * p ! 0.001 by comparison with P. lung are thought ot be less stable in asthmatic subjects and may be involved in the mechanism of response to inhalation of the UNDW (‘fog’) [7, 8]. The present study was designed to assess whether pretreatment with glutathione (G) would modify the effect on FEV-1 of ultrasonically nebulised distilled water (UNDW-‘fog’) challenge. G pretreatment was compared to placebo (P) and to sodium cromoglicate (SCG). Material and Methods 12 subjects (5 males and 7 females) ranging in age from 19 to 45 years (mean B SD: 28.3 B 10.6 years) with mild-to-moderate bronchial asthma were selected. All the patients were non-smokers and each subject was required to be free of respiratory infection symptoms for 4 weeks before the study. They demonstrated an improvement of 15% or more in the FEV-1 after inhalation of salbutamol sulfate and were positive to UNDW ‘fog’ challenge (with a 20% fall in FEV-1 from prechallenge value). No subject was receiving oral steroids or inhaled sodium cromoglycate. Methylxanthine products were stopped for 24 h, antihistamines were stopped for 3 days, and beta2 agonists for 12 hours before the onset of the study. A De Vilbiss Model 65 ultrasonic nebuliser delivering 3 ml/min of distilled water was employed. The subjects were connected to the ultrasonic nebuliser via a face mask and invited to breath keeping the mouth open for intervals of 30, 60 and 120 s. Spirometry (FEV-1) was performed before the fog challenge (‘prechallenge’ recording) and within 1 min after each fog inhalation, until they reached a 20% fall in FEV-1 or the subjects completed all the steps. A pause of 5 min was observed between each inhalation. Forced expiratory volume in 1 s (FEV-1) was measured with a dry-wedge spirometer (Vitalograph), the highest of three attempts being used for analysis. The study design was double-blind, cross-over, placebo-controlled. On the 3 study days the selected subjects were pretreated 30 min before the challenge with either nebulised inhaled G (600 mg in 5 ml of saline water), SCG (20 mg of nebulised solution) or P (saline). Glutathione solution (600 mg) was provided by Biomedica Foscama Industries SpA (Rome, Italy) and reconstituted with 5 ml of 0.9% NaCl. The percentage of reduced G in the preparation was above 97%. Aerosolisation did not alter the form of G. Each study day was separated by at least 3 days. The order of G, SCG and P was determined at random. All subjects were challenged at the same time of day. A baseline measurement of FEV-1 was made before pretreatment. All subjects gave informed written consent and the study had the approval of the local ethics committee. The protective effect of G was assessed by expressing the mean maximum decrease in FEV-1 postchallenge as percentage of the mean prechallenge FEV-1 value. Comparison of the mean decreases in FEV-1 among treatments was made by the Anova test. The difference with a p value of 0.05 or less was considered statistically significant. The results are given as means with standard deviations in parentheses.