Objective To establish a rat model of chronic pulmonary infection by inoculating Pseudomonas aeruginosa to Sprague-Dawley(SD) rats.Metods Sixty SD rats were divided into 2 groups,ie.the P.aeruginosa group and the control group. Silicone tube precoated with P.aeruginosa was placed into the main bronchus. For the control group, sterile silicon tube was intubated. Results P ． aeruginosa was detected from lung tissue of rats in infected groups.Bacterial number was higher than 103cfu ／ g 28 days after inoculation.The pathological study showed fibrinous proliferation and granulomas formation in the lungs of infected rats 28 days after inoculation.Microscopy examination showed a inflammation predominantly with lymphocyte infiltration.In control group, no bacterial and pathological changes could be detected. Conclusions The animal model with P.aeruginosa chronic pulmonary infection can be established successfully by silicone tubes precoated with P.aeruginosa intubated into the main bronchus.
Objective To examine the effects of Pseudomonas aeruginosa(PA)quorum-sensing systems on airway mucus hypersecretion．Methods Sixty Sprague-Dawley rats were intubated with a silicone tube pre-coated with PAO1(wild-type PA strain)，PAO1-JP2(quorum-sensing-mutant strain)or saline in the bronchus．After 28 days，the mRNA and protein expression of MUC5AC in the rats’bronchial epithelia were detected by RT-PCR，alcian blue／periodic acid—Schif(AB／PAS)staining and enzyme linked immunosorbent assay(ELISA)．Results In the PAO1 group，bronchiolar epithelium goblet cells by AB／PAS staining was significantly more than those in the PAO1-JP2 and control groups(both Plt;0．05)．The expression level of MUC5AC mRNA in the PAO1 group was significantly higher than those in the PAO1-JP2 and control groups(both P lt;0．05)．The ELISA showed that the concentration of MUC5AC protein in bronchoalveolar lavage fluid(BALF)in the PAO1 group was much higher than that in the PAO1-JP2 group(P lt;0．05)．Conclusion PA quorum-sensing system plays an important role in airway mucus hypersecretion
Objective To explore the role of CD4+CD25+ Treg cells in chronic pulmonary infection caused by Pseudomonas aeruginosa(PA).Methods Sixty SD rats were randomly divided into a PA group and a control group(n=30 in each group).Chronic lung infection model was established by implantation of silicone tube precoated with PA into the main bronchus.Twenty-eight days later Treg cells in peripheral blood were measured by fluorescence-activated cell sorting（FACS）.Levels of IL-10 and TGF-β in serum were assayed by ELISA.The expression of Foxp3 mRNA in spleen was measured by RT-PCR.Pathological changes of lung tissue were studed by HE staining.Results Treg/CD4+ T cells in the PA group were significantly more than those in the control group[（19.79±6.45）% vs （5.15±0.47）%，Plt;0.05].The levels of IL-10 and TGF-β were (231.52±54.48)pg/mL and （121.05±7.98）pg/mL in the PA group respectively，which were significantly higher than those in the control group[（35.43±23.56）pg/mL and （36.02±8.94）pg/mL].The expression of Foxp3 mRNA in the PA group was significantly higher compared with the control group(0.80±0.044 vs 0.25±0.054，Plt;0.05）.HE staining revealed that PA caused a intensive inflammatory reaction with lymphocytes infiltration.Conclusion CD4+CD25+ Treg cell is up-regulated and plays an important role in chronic lung infection caused by Pseudomonas aeruginosa.