Abstract
Airway hyperresponsiveness (AHR) is one of the main pathologic features of bronchial asthma, which is largely attributable to enhanced contractile response of asthmatic airway smooth muscle. Although β2 adrenergic receptor agonists are commonly used to relax airway smooth muscle for treating AHR, there are side effects such as desensitization of long-term use. Therefore, it is desirable to develop alternative relaxant for airway smooth muscle, preferably based on natural products. One potential candidate is the inexpensive and widely available natural herb saponins of Dioscorea nipponicae (SDN), which has recently been reported to suppress the level of inflammatory factor IL-17A in ovalbumin-induced mice, thereby alleviating the inflammation symptoms of asthma. Here, we evaluated the biomechanical effect of SDN on IL-17A-mediated changes of cultured human airway smooth muscle cells (HASMCs) in vitro. The stiffness and traction force of the cells were measured by optical magnetic twisting cytometry (OMTC), and Fourier transform traction microscopy (FTTM), respectively. The cell proliferation was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetry, the cell migration was measured by cell scratch test, and the changes of cell cytoskeleton were assessed by laser confocal microscopy. We found that the stiffness and traction force of HASMCs were enhanced along with the increases of IL-17A concentration and exposure time, and SDN treatment dose-dependently reduced these IL-17A-induced changes in cell mechanical properties. Furthermore, SDN alleviated IL-17A-mediated effects on HASMCs proliferation, migration, and cytoskeleton remodeling. These results demonstrate that SDN could potentially be a novel drug candidate as bronchodilator for treating asthma-associated AHR.