Role of TLR2 and its related cytokines in Legionella infection

Objective To explore the role of Toll like receptor 2(TLR2) and its related cytokines in Legionella infection by in vitro experiment.Methods Peripheral blood mononuclear cells(PBMCs) were obtained from healthy subjects(n=30) and were stimulated with live Legionella pneumophila(Lp) for 18,24,and 72 hours.The mRNA expression levels of TLR2 and myeloid differentiation factor 88(MyD88) in PBMCs were determined using real-time reverse transeription PCR(RT-PCR).The expression levels of tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β),and interleukin-6(IL-6) were measured with enzyme-linked immunosorbent assay(ELISA).Results TLR2 mRNA expression level was not significantly different between stimulation group and control group in 18 hours(P >0.05).TLR2 mRNA expression level of stimulation group was significantly higher than that of control group(1.3479±0.0562 vs.1.4259±0.0387,P <0.05) in 24 hours.The MyD88 mRNA expression level of stimulation group was significantly higher than that of control group(1.4140±0.0449 vs.1.6844±0.0426,P <0.05) in 18 hours.The MyD88 mRNA expression level was not statistically significantly different between stimulation group and control group in 24 hours(P >0.05).TLR2 mRNA and MyD88 mRNA expression levels of stimulation group were significantly lower than those of control group(P <0.05) in 72 hours.The concentration of TNF-α,IL-1β and IL-6 for Legionella stimulation group were significantly higher than those of the control group(P <0.05) in 18,24 and 72 hours.Conclusion Our study showed that TLR2 and its related inflammatory cytokines TNF-α,IL-1β and IL-6 can effectively resist Legionella infection and TLR2 mediated innate immunity may be a protective factor for Legionella infection.