Effects of recombinant fusion protein interleukin-17F/His on expression of immune-related inflammatory factors in mouse model with Streptococcus pneumoniae infection / 中华实用儿科临床杂志

ABSTRACT

Objective To evaluate the effects of recombinant fusion protein interleukin-17F/His (IL-17F/His) on expression of immune-related inflammatory factors in murine models with Streptococcus pneumoniae (SP) infection.Methods BALB/c mice were randomly divided into SP infection group,fusion protein intervention group and the normal control group.Before intranasal infection with SP,the mice were treated with PBS or IL-17F/His respectively.The number of bacteria and leukocytes in bronchoalveolar lavage fluid (BALF) was counted,and the mRNA levels of β-defensin-2 (Defb2),macrophage inflammatory protein (MIP)-lα and MIP-2β in lung tissue were detected by real-time fluorescent quantitative PCR,the concentrations of MIP-1 α,MIP-2β,IFN-γ and IL-4 in BALF,supematants of spleen cell and mediastinal lymph node cell were assayed by enzyme linked immunosorbent assay.The expressions of IL-17F and Defb2 in lung tissues were observed with immunocytochemistry.Results 1.Compared with the SP infection group,in the fusion protein intervention group,the total number of WBC (209.00 ± 18.23) was higher,the number of neutrophil,macrophage and lymphocyte[(8.67 ±2.16) × 106/L,(193.50 ± 16.50) × 106/L,(6.83 ± 1.17) × 106/L] were higher in BALF(U/F =38.097,28.854,32.942,27.810,all P ＜ 0.05),while the number of bacteria [2.75 (1.15-3.09) × 103/L] was significantly lower(P =0.02).2.Compared with SP infection group,the expression levels of Defb2 mRNA and MIP-1α mRNA(31.64 ±4.97,5.81 ± 1.09) in lung tissues were higher in the fusion protein intervention group,while the expression level of MIP-2β mRNA (6.69 ± 2.05) was lower (t =4.889,2.306,3.536,all P ＜ 0.05).3.Compared with the SP infection group,the concentration of MIP-2β [(64.15 ± 13.41) ng/L] was significantly decreased and concentration of IL-4 [(92.28 ± 4.52) ng/L] was significantly increased in BALF in the fusion protein intervention group(H/F =159,289,40.767,all P ＜0.01).4.Compared with the SP infection group,the concentrations of MIP-2β and IL-4 [(255.02 ± 13.95) ng/L,(107.02 ± 7.53) ng/L] were both significantly increased in spleen cell culture supematants in the fusion protein intervention group,the concentrations of MIP-1 α and IFN-γ [(413.61 ± 24.23) ng/L,(98.88 ± 5.84) ng/L] were both significantly decreased (all P ＜ 0.05).5.Immunocytochemistry analysis revealed that the expressions of IL-17F and Defb2 were both higher in the fusion protein intervention group than those in the SP infection group; there was no expression in the normal control group.Conclusions Intranasal inoculation of recombinant fusion protein IL-17F/His can promote pulmonary neutrophil and macrophage recruitment and increase bacterium clearance,and enhance the host defense against SP infection through increa-sing the expression of defensins,regulating the levels of MIP,IL-4 and IFN-γ.