* Drs. Zhu-Quan Su, Zi-Qing Zhou, and Wei-Jie Guan are co-first authors.
Acknowledgments: We thank Prof. Zheng Jing-ping, Prof. Gao Yi, Prof. Xie Yan-qing, Dr. An Jia-ying, Dr. Wu Zhong-ping, Dr. Yu Xin-xin and Dr. Liu Wen-ting. (State Key Laboratory of Respiratory Disease, National Clinical Research center for Respiratory Disease, Guangzhou Institute of Respiratory Health, First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University) for their technical assistance in the pulmonary function test.