<i>N</i> -Acetylcysteine and Its Therapeutic Potential in an Animal Model of Allergic Asthma

<b><i>Background:</i></b> <i>N</i>-acetylcysteine (NAC) is a classical mucolytic agent that, in addition to its mucolytic activity, also exhibits antioxidant activity. This could be beneficial in treating chronic inflammatory airway diseases, including asthma. <b><i>Background:</i></b> We evaluated the ability of NAC to modulate airway defense mechanisms, airway reactivity, inflammation, and remodeling after 10 days of administration [20 and 60 mg/(kg·d)] in an experimental guinea pig model of allergic inflammation. <b><i>Methods:</i></b> The concentrations of inflammatory cytokines (interleukins: IL-4, IL-5, IL-10, IL-12, and IL-13), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) were measured in bronchoalveolar lavage fluid using a multiplex detection method. The concentration of remodeling marker transforming growth factor beta-1 (TGF-β1) was measured in lung homogenates using enzyme-linked immunosorbent assay. <i>In vivo,</i> changes in specific airway resistance and number of cough efforts were determined. Tracheal smooth muscle reactivity was evaluated <i>in vitro</i>. Ciliary beat frequency (CBF) indicated mucociliary clearance. <b><i>Results:</i></b> A 10-day administration of NAC at a higher dosage led to a significant decrease in the regulatory cytokines IL-4, IL-5, and GM-CSF. NAC, in both dosing schedules, decreased the levels of TGF-β1. NAC at a higher dosage reduced the number of chemically induced cough reflexes and CBF. NAC did not affect airway hyperreactivity parameters. <b><i>Conclusion:</i></b> NAC is a multifactorial drug, and under our experimental conditions of allergic inflammation, it showed positive effects on the levels of regulatory cytokines and growth factors, which probably led to a reduction in the intensity of airway defense mechanisms.