Observation of inflammation and macrophage polarization in an experimental model of cigarette smoke-exposed mice and cigarette smoke extract (CSE)-induced RAW264.7 cells: An experimental preclinical study.

INTRODUCTION

The present study aimed to investigate macrophage polarization imbalance and its association with sustained NF-κB/NLRP3 signaling under chronic inflammatory stimulation using both in vivo and in vitro COPD-related models.

METHODS

This experimental preclinical study was conducted between March and September 2023, at Shanghai Tenth People's Hospital. A chronic obstructive pulmonary disease (COPD)-like inflammatory model was established in C57BL/6J mice (n=5 per group) through combined chronic cigarette smoke (CS) exposure (4 hours/day, 5 days/week for 15 weeks) and intranasal lipopolysaccharide (LPS) administration (7.5 μg on days 1 and 14), together with an in vitro cigarette smoke extract (CSE)-induced RAW264.7 macrophage model (10% CSE for 24 hours). Macrophage M1/M2 polarization and inflammatory responses were assessed using ELISA, qRT-PCR, immunohistochemistry, Western blotting, and flow cytometry.

RESULTS

Airflow limitation was observed in CS-exposed model mice, with significant reductions in FEV0.05/FVC (21.70 ± 0.96 vs 27.50 ± 0.94%, p<0.0001) and FEV0.1/FVC (77.39 ± 2.62 vs 87.21 ± 1.95%, p<0.001), along with increased lung resistance (RL: 1.22 ± 0.13 vs 0.97 ± 0.02 cmH2O/(mL/s), p<0.01). Histological examination revealed thickened bronchial walls, disrupted alveolar structure, and inflammatory cell infiltration. TNF-α (BALF: 290.6 ± 7.58 vs 125.6 ± 5.30 pg/mL, p<0.0001), IL-6 (BALF: 67.92 ± 3.02 vs 44.42 ± 2.62 pg/mL, p<0.001), and IL-1β (BALF: 120.3 ± 8.24 vs 87.52 ± 3.40 pg/mL, p<0.01) levels increased dramatically in both CS-exposed mice and CSE-induced RAW264.7 cells, whereas IL-10 levels decreased (BALF: 46.12 ± 1.71 vs 77.19 ± 3.96 pg/mL, p<0.001).

CONCLUSIONS

CS and CSE exposure induced M1 macrophage polarization in mice, as well as 10% CSE-induced RAW 264.7 cells, which may be related to the activation of the NF-κB/NLRP3 signaling pathway.