Inhibition of airway remodeling and inflammation by isoforskolin in PDGF-induced rat ASMCs and OVA-induced rat asthma model

Isoforskolin (ISOF) has been reported to play an important role in many illnesses including respiratory, cardiovascular and ophthalmologic diseases. In our study, we aimed to investigate how ISOF regulates airway remodeling and inflammation in asthma. Based on SO2-stimulated mouse cough model, we assessed the role of ISOF in cough and secretion of phlegm. Afterwards, platelet derived growth factor (PDGF)-induced primary rat airway smooth muscle cell (ASMC) model and ovalbumin (OVA)-induced rat asthma model were used to continue our following research. Our results showed that ISOF could prolong the cough latent period, reduce the cough times in two minutes, and increase the excretion of red phenol, which suggested the antitussive and expectorant effects of ISOF. Besides, ISOF pretreatment reversed the hypotonicity and cytoskeleton remodeling in PDGF-induced ASMCs, and reduced mucus hypersecretion and collagen overdeposition in OVA-induced rat asthma model, which indicated its inhibition on airway remodeling in vitro and in vivo. Moreover, ISOF reduced the invasion of inflammatory cells into bronchoalveolar lavage fluid (BALF) and lungs, which revealed its inhibitory role in airway inflammation. The down-regulation of transforming growth factor β1 (TGF-β1) and interleukin-1β (IL-1β) upon ISOF treatment might be responsible for its anti-remodeling and anti-inflammation roles. In conclusion, ISOF can reduce cough and sputum, as well as inhibit airway remodeling and inflammation by regulating the expression of TGF-β1 and IL-1β. These data indicate the potency of ISOF in treating asthma and also provide insights into the development of new anti-asthma agent.