Heng Xu1, Naigang Chen2, Chen Li3. 1. School of Life Sciences, Beijing University of Chinese Medicine, Beijing, 100029, China. 2. Department of Rheumatology, Fangshan Hospital, Beijing University of Chinese Medicine, Beijing, 102400, China. 3. Department of Rheumatology, Fangshan Hospital, Beijing University of Chinese Medicine, Beijing, 102400, China. casio1981@163.com.