Comparison of the antioxidant status in tracheal and bronchoalveolar epithelial lining fluids in recurrent airway obstruction

Summary Reasons for performing study: Following a period of airway inflammation the clearance of inflammatory cells along the mucociliary escalator may impose a considerable oxidant load on the trachea. Objectives: To determine the degree of oxidative stress in tracheal epithelial lining fluid (ELF) in comparison to that present in peripheral airways after an acute exposure to organic dust. Methods: Tracheal wash fluid and bronchoalveolar lavage fluid (BALF) were collected for cytology and antioxidant analyses from 6 recurrent airway obstruction (RAO)-affected horses and 6 healthy control horses before and after stabling on straw bedding for 24 h. Results: In RAO-affected horses, organic dust exposure resulted in a significant decrease in ascorbic acid concentration in tracheal ELF (P < 0.0001), which was greater than the decrease in bronchoalveolar ELF (P = 0.0003). The percentage decrease in tracheal ELF ascorbic acid correlated with the percentage decrease in bronchoalveolar ELF ascorbic acid (r = 0.76; P = 0.004) following exposure. Conclusions: Acute organic dust exposure results in significant antioxidant depletion in the trachea, which may reflect inflammation and oxidative processes in peripheral airways. Potential relevance: Further work is required to evaluate the role of ascorbic acid depletion in the pathogenesis of RAO.