Cytokine changes of biofilm in a rat model of chronic pseudomonas aeruginosa pulmonary infection

Objective:To observe the cytokine modulating effect of biofilm in a rat model of chronic pseudomonas aeruginosa pulmonary infection. Methods:Rats were challenged intratracheally with alginate embedded PA strain PAO579 in the concentration of 1×109 colony-forming units per milliliter (CFU/ML)and saline was used as a placebo. Two weeks later intratracheal challenge with P. aeruginosa,parameters was evaluated. Results:Two weeks after challenge,a significant infiltration of numerous polymorphonuclear leukocytes (PMN) in the lung tissues with higher IL-4、TNF-α and lower IFN-γ production in the lungs were found in the PA-infected group compared to the placebo group and nomal control group (P0.01,P0.001). Meanwhile,the incidence of chronic inflammatio (MN≥90%, PMN≤10%) was significantly lower than acute inflammation(PMN≥90%,MN≤10%)in the PA-infected group(P0.05). Conclusion:PA biofilm can induce Th2 like immune responses (antibody-mediated immunity) which might lead to lung tissues damage of Ⅲ type hypersensitivith with infiltrating numerous PMN.