Wen Hua1, Hui Liu1, Li-Xia Xia1, Bao-Ping Tian1, Hua-Qiong Huang1, Zhi-Yang Chen2, Zhen-Yu Ju2, Wen Li1, Zhi-Hua Chen1, Hua-Hao Shen1,3. 1. Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China. 2. Institute of Aging Research, Hangzhou Normal University College of Medicine, Hangzhou, Zhejiang, China. 3. State Key Laboratory of Respiratory Diseases, Guangzhou, Guangdong, China.
Abstract
BACKGROUND AND OBJECTIVE: The mammalian target of rapamycin (mTOR) signalling pathway regulates immune responses, and promotes cell growth and differentiation. Inhibition of mTOR with rapamycin modulates allergic asthma, while the underlying molecular mechanisms remain elusive. Here, we demonstrate that rapamycin, effectively inhibits eosinophil differentiation, contributing to its overall protective role in allergic airway inflammation. METHODS: Rapamycin was administered in a mouse model of ovalbumin-induced allergic airway inflammation, and the eosinophil differentiation was analysed in vivo and in vitro. RESULTS: Rapamycin significantly attenuated allergic airway inflammation and markedly decreased the amount of eosinophils in local airways, peripheral blood and bone marrow, independently of levels of interleukin-5 (IL-5). In vitro colony forming unit assay and liquid culture demonstrated that rapamycin directly inhibited IL-5-induced eosinophil differentiation. In addition, rapamycin reduced the production of IL-6 and IL-13 by eosinophils. Rapamycin was also capable of reducing the eosinophil levels in IL-5 transgenic NJ.1638 mice, again regardless of the constitutive high levels of IL-5. Interestingly, rapamycin inhibition of eosinophil differentiation in turn resulted in an accumulation of eosinophil lineage-committed progenitors in bone marrow. CONCLUSIONS: Altogether these results clearly demonstrate a direct inhibitory role of rapamycin in eosinophil differentiation and function, and reemphasize the importance of rapamycin and possibly, mTOR, in allergic airway disease.
BACKGROUND AND OBJECTIVE: The mammalian target of rapamycin (mTOR) signalling pathway regulates immune responses, and promotes cell growth and differentiation. Inhibition of mTOR with rapamycin modulates allergic asthma, while the underlying molecular mechanisms remain elusive. Here, we demonstrate that rapamycin, effectively inhibits eosinophil differentiation, contributing to its overall protective role in allergic airway inflammation. METHODS:Rapamycin was administered in a mouse model of ovalbumin-induced allergic airway inflammation, and the eosinophil differentiation was analysed in vivo and in vitro. RESULTS:Rapamycin significantly attenuated allergic airway inflammation and markedly decreased the amount of eosinophils in local airways, peripheral blood and bone marrow, independently of levels of interleukin-5 (IL-5). In vitro colony forming unit assay and liquid culture demonstrated that rapamycin directly inhibited IL-5-induced eosinophil differentiation. In addition, rapamycin reduced the production of IL-6 and IL-13 by eosinophils. Rapamycin was also capable of reducing the eosinophil levels in IL-5 transgenic NJ.1638 mice, again regardless of the constitutive high levels of IL-5. Interestingly, rapamycin inhibition of eosinophil differentiation in turn resulted in an accumulation of eosinophil lineage-committed progenitors in bone marrow. CONCLUSIONS: Altogether these results clearly demonstrate a direct inhibitory role of rapamycin in eosinophil differentiation and function, and reemphasize the importance of rapamycin and possibly, mTOR, in allergic airway disease.