Establishment and characterization of a mouse model with chronic pneumonia infected by Pseudomonas aeruginosa.

INTRODUCTION: Pseudomonas aeruginosa is a clinically significant opportunistic pathogen causing both acute and chronic pneumonia infections. However, constructing an animal model for chronic infection remains challenging, hindering research advancement in this field. AREAS COVERED: This study employed microfluidic technology to prepare alginate-encapsulated P. aeruginosa microspheres and established a chronic pneumonia model in C57BL/6J mice following aerosolized intratracheal (i.t.) delivery of the encapsulated bacteria. Comprehensive evaluation included bacterial load measurement, histopathological analysis by hematoxylin and eosin (H&E) staining, inflammatory cytokine detection by enzyme-linked immunosorbent assay (ELISA), immune cell profiling (flow cytometry), and transcriptomic analysis by RNA sequencing (RNA-seq). EXPERT OPINION: We successfully established a mouse model of P. aeruginosa-induced chronic pneumonia with persistent bacterial colonization (~2,000 colony-forming units (CFU)/g at day 14), consistent histopathological features across independent experiments, and sustained elevation of inflammatory cytokines. At 14 days post-challenge, mice maintained high bacterial loads (2,000 CFU/g) with obvious lung histopathological damage. The model exhibited gradual body weight decrease, elevated inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and serum, and increased neutrophils, macrophages, and NK cells in lung tissue. RNA-seq revealed upregulation of inflammation and pathogen resistance genes, with downregulation of metabolic process genes. This approach combines microfluidic-generated alginate microspheres with non-surgical aerosolized i.t. delivery, providing a reproducible platform for investigating chronic infection mechanisms in P. aeruginosa pneumonia research.