1. Department of Otorhinolaryngology, Tangdu Hospital, Fourth Military Medical University, #1 Xinsi Road, Xi’an, Shaanxi 710032, China
2. Institute of Medical Research, Northwestern Polytechnical University, #127 West Youyi Road, Xi’an, Shaanxi 710032, China
3. Department of Periodontology, School of Stomatology, Fourth Military Medical University, #145 West Changle Road, Xi’an, Shaanxi 710032, China
4. Department of Immunology, Fourth Military Medical University, #169 West Changle Road, Xi’an, Shaanxi 710032, China