Establishment of COPD mouse model
All animal experiments were performed in accordance with the animal ethics approval of The First Affiliated Hospital of Hunan Normal University (Hunan Provincial People’s Hospital, 2021 No. 43). C57BL/6 male mice (6–8 weeks) were purchased from SLAC Laboratory (Shanghai, China) and kept in an animal facility at 21 ~ 24 °C for 12/12 h with light and dark cycles and free access to water and food. Mice were randomly divided into Air + pc-NC group, Cigarette smoke (CS) + pc-NC group and CS + pc-SOCS5 group (n = 6/per group). In brief, mice were exposed to room air or CS of five cigarettes (Furongwang, HUNAN Tobacco Industrial Co., Ltd. China) four times each day for 30 min/time, 5 days/weeks for up to 24 weeks. The lentivirus-packed SOCS5 overexpressing vector (pc-SOCS5) and empty vector (pc-NC) assembled by GenePharma (Shanghai, China) were intranasally injected into the mice once every 2 weeks (2 × 10