IL-17B regulates Listeria monocytogenes infection by inhibiting macrophage infiltration / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the related mechanism of IL-17B in regulating host immune response by studying the role and mechanism of IL-17B in the infection of Listeria monocytogenes in mice. Methods:Eighteen male C57BL/6 mice were randomly divided into three groups with six in each group control group, PBS group and wild-type (WT) group. The control group was not given any treatment. The mice in the PBS group were injected with 100 μl of sterile PBS, while C57BL/6 mice in the WT group and IL-17B deficient (IL-17B -/-) male mice were injected intravenously with 100 μl of Listeria monocytogenes 19115 (2×10 4 colony forming unit). The mice were sacrificed 48 h after infection and then peripheral blood, spleen and liver samples were collected. Bacterial colonization in mouse spleen and liver was detected by plate count method; HE staining was used to evaluate histopathological damages; flow cytometry was used to detect the immune cells in different tissues. ELISA and qRT-PCR were used to detect the levels of IL-1β, IL-6, IL-12p40, TNF-α, IFN-γ and iNOS in serum and spleen. qRT-PCR were used to detect the expression of IL-17B and IL-17RB. Results:Bacterial colonization in mouse spleen was reduced in the IL-17B -/- group as compared with that in the WT group ( P<0.05). Compared with the PBS group, Listeria monocytogenes infection increased the expression of IL-17B and IL-17RB in mouse spleen ( P<0.05, P<0.01). There was no significant difference in the pathological damages in spleen between WT and IL-17B -/- groups. Moreover, compared with the WT group, the IL-17B -/- group showed increased macrophages, M1 macrophages ( P<0.01) and NK cells ( P<0.05) in spleen, up-regulated macrophages ( P<0.05) and M1 macrophages ( P<0.01) in the peripheral blood, enhanced expression of IL-6 in serum and spleen ( P<0.05), and promoted expression of IL-6, IL-12, IL-1β, TNF-α, IFN-γ and iNOS in spleen. Conclusions:IL-17B might inhibit Listeria monocytogenes clearance by inhibiting macrophage infiltration and the secretion of IL-6.