1. State Key Laboratory of Respiratory Disease Guangzhou Institutes of Biomedicine and Health (GIBH) Chinese Academy of Sciences Guangzhou 510530 China
2. School of Public Health (Shenzhen) Sun Yat‐sen University Guangdong 518107 China
3. Guangzhou Eighth People's Hospital Guangzhou Medical University Guangzhou 510182 China
4. Mucosal Immunology Unit King's College London at Guy's Hospital London WC2R 2LS UK