Protective Effect of N-Acetyl Cysteine in Airway Hyper-Reactivity
N-acetyl cysteine (NAC) reduces airway responsiveness after diesel exhaust exposure in individuals with hyper-responsive airways, a study published in June 2014 reports. Reactive airways dysfunction syndrome and irritant-induced asthma are closely related and result in respiratory symptoms in the minutes or hours after a single inhalation of a high concentration of irritant gas, aerosol, or smoke.
Twenty-six non-smoking adults underwent three separate experimental conditions to evaluate the impact of NAC on airway responsiveness. The subjects received 600 mg NAC or placebo three times per day for six days. On the sixth day, the subjects underwent an experiment in which they were exposed for two hours to either filtered air or diesel exhaust (300 mcg/m3 of particulate matter smaller than 2.5 microns). The subjects underwent 1) filtered air with placebo, 2) diesel exhaust with placebo, and 3) diesel exhaust with NAC including a two-week “wash-out” period between each of the experiments. The researchers measured airway responsiveness using a methacholine challenge before and after each two-hour exposure experiment.
NAC supplementation reduced baseline airway responsiveness in hyper-responsive individuals by 20 percent. The researchers showed that among the hyper-responsive subjects, airway responsiveness increased by 42 percent after exposure to diesel exhaust compared to filtered air, and NAC supplementation inhibited this increase.
The study authors stated, “Antioxidant (N-acetyl cysteine) supplementation protects against increased airway responsiveness associated with diesel exhaust inhalation and reduces need for supplement bronchodilators in those with baseline airway hyper-responsiveness. Individuals with variants in genes of oxidative stress metabolism when exposed to diesel exhaust are protected from increases in airway responsiveness if taking antioxidant supplementation. “
Reference:
Carlsten C, et al. Toxicol Sci. 2014 Jun;139(2):479-87.
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