Xianhua Gui1, Liyun Miao2, Hourong Cai1, Fanqing Meng3. 1. Department of Respiratory Medicine, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, Jiangsu 210008, China. 2. Department of Respiratory Medicine, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, Jiangsu 210008, China. Email: liyunmiao462@163.com. 3. Department of Pathology, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, Jiangsu 210008, China.