IL-17B通过抑制巨噬细胞浸润调控单核细胞增生性李斯特菌感染

IL-17B regulates Listeria monocytogenes infection by inhibiting macrophage infiltration

目的通过研究IL-17B在小鼠单核细胞增生性李斯特菌感染中的作用和机制,探讨IL-17B调控宿主免疫应答的相关机制。方法C57BL/6雄鼠(n=18)随机分成空白对照组、PBS组和李斯特菌感染组(野生型,WT),每组6只。空白对照组不做处理,PBS组小鼠尾静脉注射100μl无菌PBS,WT组小鼠和IL-17B缺陷(IL-17B^(-/-))雄鼠尾静脉注射100μl单核细胞增生性李斯特菌19115,每只2×104个菌落形成单位(CFU)。感染48 h后处死小鼠,取小鼠外周血、脾脏和肝脏,以涂板计数法检测脾脏和肝脏中的细菌定植量;HE染色评估组织病理学损伤;流式细胞术检测各组织中免疫细胞的变化;ELISA和qRT-PCR检测血清或脾脏中IL-1β、IL-6、IL-12p40、TNF-α、IFN-γ、iNOS的水平,qRT-PCR检测IL-17B、IL-17RB的水平。结果与WT组比较,IL-17B^(-/-)小鼠脾脏荷菌量减少,差异有统计学意义(P<0.05)。与PBS组比较,C57BL/6小鼠感染单核细胞增生性李斯特菌后脾脏中IL-17B和IL-17RB表达水平显著增加(P<0.05,P<0.01)。WT组和IL-17B^(-/-)组小鼠脾脏病理损伤差异无统计学意义。与WT组比较,IL-17B^(-/-)小鼠脾脏中巨噬细胞、M1型巨噬细胞显著增加(P<0.01),NK细胞也显著增加(P<0.05),外周血中巨噬细胞和M1型巨噬细胞显著增加(P<0.05,P<0.01),血清和脾脏中IL-6表达增加(P<0.05),脾脏中IL-6、IL-12、IL-1β、TNF-α、IFN-γ、iNOS mRNA水平升高(P<0.05)。结论IL-17B可通过抑制巨噬细胞浸润、IL-6的分泌抑制宿主清除单核细胞增生性李斯特菌。

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 100μl of sterile PBS,while C57BL/6 mice in the WT group and IL-17B deficient(IL-17B^(-/-))male mice were injected intravenously with 100μl of Listeria monocytogenes 19115(2×104 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-γand 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-γand iNOS in spleen.Conclusions IL-17B might inhibit Listeria monocytogenes clearance by inhibiting macrophage infiltration and the secretion of IL-6.