Cigarette Smoke and LPS-Induced COPD Mouse Model

Six- to eight-week-old male C57 mice were purchased from Charles River (Beijing, China) and kept under SPF conditions (12 h light/dark cycle) at a temperature of 24°C ± 2°C and 50%–60% humidity. Mice were provided water and food freely. The animal experiment was approved by the Animal Health Research Institute of Guangdong Academy of Agricultural Sciences (ethics no. SPF2020034). After a 1-week quarantine period, mice were randomly divided into the following groups: 1) control group (CTL), 2) COPD model group (MOD), 3) COPD + roflumilast (POS group, 0.5 mg/kg/d), 4) COPD + BFHX low-dose group (low group, 1.9 g/kg/d, based on the clinical dose), and 5) COPD + BFHX high-dose group (high group, 3.8 g/kg/d), n = 9 per group. All groups, except the CTL group, received cigarette smoke (CS) exposure and lipopolysaccharide (LPS) instillation, as described previously (Guan et al., 2020 (link)). Mouse airways were instilled with PBS or LPS (75 μg in 50 μL) on experimental days 1 and 14; all mice, except the CTL group, received CS exposure for 4 h with 4 h intervals. The animals were orally administered on the 61st day of the experiment for 30 days, the weights of the animals were recorded, and their states, including their hair status and movement, were observed. After administration, the animal was harvested for further analysis (n = 5–6 mice per group were analyzed).