Organic Dust and Airway Hyperresponsiveness in Precision-Cut Lung Slices of Indoor and Outdoor-Raised Pigs
Description
Airway hyperresponsiveness (AHR) is a symptom of asthma and chronic bronchitis, pulmonary conditions common among agricultural workers exposed to organic dust (OD). Exposure to OD of biological materials has been shown to promote inflammatory responses that lead to AHR. We hypothesized that continuous exposure to OD in swine barns evokes AHR. Precision-cut lung slices (350 μm) from indoor and outdoor-raised pig lungs were prepared and exposed to organic dust extract, endotoxin (LPS), or media for 24 hours, followed by stimulation with a methacholine (MCh) dose gradient (10-7 – 10-4, 5 minutes each), and subsequently with chloroquine (ChQ), for 10 minutes. Time-lapse images were captured every minute during airway contraction and relaxation. Airway contractility was determined by measuring the percentage area of each lumen compared to the baseline (media). Differences between the groups were determined using two-way ANOVA (p<0.05). Outdoor- raised pigs displayed higher airway sensitivity to methacholine following organic dust exposure compared to indoor-raised pigs. This suggests that outdoor-raised pigs may have acute sensitivity due to a lack of prior organic dust exposure. In contrast, indoor-raised pigs may have developed adaptation response from prolonged exposure to organic dust. These studies may provide insight for understanding AHR in agricultural workers. agricultural workers exposed to organic dust (OD). Exposure to OD of biological materials has been shown to promote inflammatory responses that lead to AHR. We hypothesized that continuous exposure to OD in swine barns evokes AHR. Precision-cut lung slices (350 µm) from indoor and outdoor-raised pig lungs were prepared and exposed to organic dust extract, endotoxin (LPS), or media for 24 hours, followed by stimulation with a methacholine (MCh) dose gradient (10-7 – 10-4, 5 minutes each), and subsequently with chloroquine (ChQ), for 10 minutes. Time-lapse images were captured every minute during airway contraction and relaxation. Airway contractility was determined by measuring the percentage area of each lumen compared to the baseline (media). Differences between the groups were determined using two-way ANOVA (p<0.05). Outdoor- raised pigs displayed higher airway sensitivity to methacholine following organic dust exposure compared to indoor-raised pigs. This suggests that outdoor-raised pigs may have acute sensitivity due to a lack of prior organic dust exposure. In contrast, indoor-raised pigs may have developed adaptation response from prolonged exposure to organic dust. These studies may provide insight for understanding AHR in agricultural workers.