Effects of quorum-sensing system on CD4+ CD25+ Treg cell in Pseudomonas aeruginosa

YANG Qingmei; SHEN Ce

Abstract：Objective To explore the effects of quorum-sensing system on CD4+CD25+Treg cell in Pseudomonas aeruginosa.Methods Sixty SD rats were divided into 3 groups: PAO1 group, PAO-JP2 (lasⅠ and rhlⅠ double mutant) group, and control group.Chronic lung infection model was set up by placing P. aeruginosa-precoated silicone tube into the main bronchus. Twenty-eight days lat-er, The Treg cell in venous blood, the IL-10 and TGF-β in serum, and the Foxp3mRNA in spleen were detected by FACs, ELISA, and RT-PCR, respectively. The pulmonary tissues were stained with HE. Results 1) Treg/CD4+T for PAO1 group was ( 19.79±6.45 )%, which was significantly higher than those of JP2 group (11.03±3.92)% and control group (5.15±0.47 )% (P<0.05).2) The levels of IL-10 and TGF-β were (231.52±54.48 ) pg/mL and ( 121.05±7.98 ) pg/mL for PAO1 group, ( 60.10±29.64)pg/mL and (63.11±5.73) pg/mL for JP2 group, while (35.43±23.56) pg/mL and (36.02±8.94) pg/mL for control group.Compared with JP2 and control group, PAO1 group expressed much more cytokines (P<0.05).3) As Foxp3mRNA expression,PAOI group (0.80±0.044 ) was higher than JP2 group (0.41±0.044 ) and control group (0.25±0.054 ) (P<0.05).4) The pathological changes: fibrinous adhesions and granulomas could be found in lungs of PAO1 infected groups. At optical mieruscopy,PAO1 caused a pronounced inflammatory reaction with lymphocytes. For JP2 group, milder inflammatory change was detected. Conclu- sion Quorum-sensing system up-regulates CD4+ CD25+ Treg cell through enhancing the expression levels of IL-10, TGF-β, and Foxp3mRNA, thus which plays an important role in chronic lung infection by Pseudomonas aeruginosa.