Pseudomonas aeruginosa (P. aeruginosa) is commonly isolated from the sputum of
COPD patients. However, the precise role of P. aeruginosa
infection in the progression of
COPD, especially its role in altering
inflammation remains unclear. Here, we designed mice models of
COPD infected with P. aeruginosa (PA) and observed dynamic changes of lung structure, lung inflammatory microenvironment, lung function. After
infection, the level of mucus secretion peaked on day 3 and remained higher throughout the study period, and the
airway remodeling and
emphysema was starkly apparent on day 14 and 21. On day 3,
interferon-γ and
interleukin (IL)- 5 levels increased rapidly, accompanied by elevated T-bet
mRNA expression and CD4+T-bet+ cells; at the late stage of
infection (days 14 and 21), consistent with increased GATA3
mRNA expression and CD4+GATA3+ cells,
IL-4 and
IL-13 levels significantly increased;
IL-17A level, Foxp3
mRNA expression, CD4+ROR-γt+ cells and CD4+FOXP3+ cells remained at higher levels throughout the course of the
infection. Small-airway function showed a decline from day 3 to day 21; large airway function showed a decline on day 14 and 21. Overall, P. aeruginosa
infection contributed to the progression of
COPD. During the
infection, an early Th1-related
inflammation gradually shifted to a later Th2-related
inflammation, and small-airway function decline occurred earlier than that of large-airway function. On the basis of infection control, the appropriate use of
glucocorticoid might slow
disease progression by mitigating the enhanced Th2-related
inflammation, and small airways could be also an important treatment target in P. aeruginosa -infected
COPD patients.