Anti-malarial drug,artesunate,as a novel therapeutic drug target for airway wall remodeling in asthma

摘要

OBJECTIVE Airway wall remodeling(AWR),which refers to structural changes in the airway,is a key characteristic of asthma.Airway smooth muscle(ASM)cell hypertrophy and hyperplasia contributes to AWR.Glucocorticoids,which are used as first line therapy for the treatment of asthma,reduce ASM proliferation but the magnitude of their anti-proliferative actions is dependent on the mitogen used.Moreover,glucocorticoid therapy is accompanied by many side effects.Artesunate,a semi-synthetic artemisinin derivative,has been widely used to treat malaria with minimal toxicity.Artesunate has been shown to attenuate allergic airway inflammation in mice.However,its role in treating AWR in asthma is not known.In this study,we hypothesize that artesunate has anti-proliferative actions on ASM cells,potentially reversing AWR.METHODS and RESULTS Quiescent primary human ASM cells were pre-treated(1h)with artesunate(3,10,30μmol·L-1)before being stimulated with either FBS(10%)or thrombin(0.3U·mL-1).Following 48 h stimulation with mitogen,cells were counted using a haemocytometer.Dexamethasone(Dex,100nmol·L-1)was used as a positive control.Artesunate concentration-dependently reduced cell number and the magnitude of inhibition appeared to be non-mitogen dependent.Moreover,we examined the effect of artesunate on two important signalling proteins involved in cell proliferation,ERK1/2phosphorylation and cyclin D1 protein levels.Artesunate reduced cyclin D1 protein levels significantly following 20 h stimulation with either thrombin or FBS but had no effect on ERK1/2 phosphorylation following 6h stimulation.Importantly,artesunate(30μmol·L-1),but not Dex,inhibited the phosphorylation of Akt,which is upstream of cyclin D1.Next,we show that the inhibitory effect of artesunate,but not Dex,on ASM cell number is retained at least 24h post-treatment following stimulation with FBS.In an acute murine model of allergic asthma,artesunate treatment decreased sm-α-actin positive cells and cyclin D1 protein abundance in the ovalbumin sensitized and challenged mice.CONCLUSION We have shown that artesunate regulates the PI3K/Akt pathway to inhibit the proliferation of primary human cultured ASM cells.This is an alternative mode of action,in comparison to glucocorticoids such as Dex.The anti-proliferative effect of artesunate was further validated in vivo.Thus,our study provides a basis for the future development of artesunate as a novel anti-AWR agent that targets ASM hyperplasia via the PI3K/Akt pathway.Moreover,artesunate may be used as an add-on therapy for asthmatic patients.