Long-term physical training leads to airway remodelling in animal model.

Background Long−term physical exercise is known to have effects on airways cellularity, epithelial cells proliferation and on extracellular matrix proteins deposition in subepithelial layer, but whether it could induce airway smooth muscle (ASM) remodelling is still unknown. Aim To test if in an animal model, long−term physical exercise in standard environmental conditions, could induce smooth muscle remodeling in central and peripheral airways. Materials and methods Sprangue Dawley rats were trained on a treadmill (total number: 9) for 1 hour per day, for 3 days per week, for a period of 3 months. After last efforts animal were sacrificed with sedentary control rats (total number: 10) of the same age and their lungs were fixed in formalin. Tissue was cut in 5 micron sections and incubated with primary monoclonal antibody for alpha−Smooth Muscle Actin (a−SMA) and then processed in standard fashion for immunoistochemistry. Control sections were processed in the absence of primary antibody. Airways were classified according to basement membrane perimeter (BMP) in central (>1mm) and in peripheral (<0.99mm). To quantify the amount of a−SMA, the area of positive staining corrected for BMP² in central and in peripheral airways was measured using Sigma−Scan software. Results Compared to sedentary rats, trained rats showed a significant increase in a−SMA both in the central (1.65+0.21 vs 1.02+0.14 m²/m², p<0.05) and in the peripheral airways (2.013+0.22 vs 1.44+0.17 m²/m², p<0.05). Conclusion Long term physical training in rat model induces airway smooth muscle mass remodelling along the airway tree, in both large and small airways.