The relationship between the expression of TLR2 and TLR4 in peripheral blood mononuclear cells and Th1/Th2 immune response in children with recurrent respiratory tract infection / 国际检验医学杂志

ABSTRACT

Objective To investigate the expression of Toll-like receptor 2(TLR2)and Toll-like receptor 4(TLR4)in peripheral blood mononuclear cells(PBMC)in children with recurrent respiratory tract infection(RRTI)and its relationship with T helper cell 1(Th1)/T helper cell 2(Th2)immune response.Methods A total of 65 children diagnosed with RRTI who admitted to the hospital from December 2020 to December 2022 were enrolled in the study as the RRTI group,and 45 healthy children who underwent physical examination in the hospital during the same period were enrolled as the control group.The relative expression levels of TLR2 and TLR4 mRNA in PBMCs were detected by real-time fluorescence quantitative PCR(qPCR).The expres-sion rates of TLR2 and TLR4 protein in PBMCs were detected by flow cytometry.The levels of Th1 cytokine interferon-γ(IFN-γ),Th2 cytokine interleukin-4(IL-4)and their ratio(IFN-γ/IL-4)in plasma were detected by enzyme-linked immunosorbent assay(ELISA).Pearson correlation analysis was used to analyze the corre-lation between TLR2,TLR4 protein expression rates and plasma IFN-γ,IL-4 levels.Results The RRTI group had significantly higher plasma level of Th2 cytokine IL-4 than the control group,significantly lower plasma level of Th1 cytokine IFN-y than the control group,and significantly lower ratio of IFN-γ/IL-4 than the con-trol group,the differences were all statistically significant(P＜0.05).The relative expression levels of TLR2 and TLR4 mRNA and protein expression rates in PBMC of children in the RRTI group were higher than those in the control group,and the differences were statistically significant(P＜0.05).Pearson correlation analysis showed that the protein expression rates of TLR2 and TLR4 in PBMC of children with RRTI were both nega-tively correlated with both plasma IFN-γ levels and IFN-γ/IL-4(P＜0.05)and positively correlated with plasma IL-4 levels(P＜0.05).Conclusion The expression of TLR2 and TLR4 in PBMC and plasma Th1/Th2 cytokines in children with RRTI may be involved in the occurrence and development of the disease.Ex-cessive activation of TLR2 and TLR4 may weaken Th1 function and enhance Th2 function.