BALB/c小鼠口服幽门螺杆菌裂解物配伍dmLT佐剂诱导黏膜局部及系统性免疫应答

Oral immunization of BALB/c mice with Helicobacter pylori lysate combined with dmLT adjuvant for the induction of mucosal and system immune responses

目的观察口服免疫幽门螺杆菌(Hp)裂解物配伍黏膜佐剂双突变大肠埃希菌热不稳定毒素(double mutant heat-labile toxin,dmLT)在BALB/c小鼠中诱导抗Hp免疫保护效果,分析相关免疫应答特点。方法将SS1(Sydney strain 1)株Hp裂解物配伍佐剂dmLT经口服免疫BALB/c小鼠后,进行幽门螺杆菌胃部活菌接种。对照组小鼠给予口服生理盐水,每只200μl。感染后6周检测幽门螺杆菌胃部定植量,采集血清、脾脏、肠系膜淋巴结、小肠、盲肠、粪便等样本进行相关免疫应答分析。结果抗原配伍佐剂免疫组小鼠与对照组相比较胃部幽门螺杆菌定植量降低;血清中检测到比对照组更强的特异性IgG抗体反应,IgG亚型主要以IgG1为主,且IgG1/IgG2a比值显著高于对照组;小肠、盲肠、粪便中均检测到较高的sIgA,小肠中最为显著,而对照组中均未有明显sIgA反应;脾和肠系膜淋巴结中IL-17+CD4+T比例与对照组相比较显著升高。结论口服免疫Hp裂解物配伍佐剂dmLT诱导黏膜局部及系统性免疫应答,增强BALB/c小鼠抗幽门螺杆菌感染,与显著增强的Th17免疫应答,以及Th细胞中Th2的极化相关,该结果为进一步评价dmLT作为黏膜佐剂用于幽门螺杆菌重组蛋白疫苗提供了实验资料。

Objective To observe the protective effects of oral immunization with Helicobacter pylori(Hp)lysates in combination with mucosal adjuvant dmLT(double mutant heat-labile toxin)against Hp infection in a BALB/c mouse model and to analyze the features of induced immune responses.Methods BALB/c mice were orally immunized with Hp lysate(Sydney strain 1,SS1 strain)and dmLT adjuvant,and then innoculated with live Hp strains through oral gavage.A control group was set up by oral administration of normal saline(200μl/mouse).The colonization of Hp strains in the stomachs of mice was measured six weeks after bacterial inoculation.Samples of serum,spleen,mesenteric lymph node(MLN),small intestine,cecum and feces were collected from mice to analyze the features of induced immune responses.Results The colonization of Hp strains in the stomachs of the immunized mice was significantly decreased as compared with that of the control group.Increased specific IgG antibody responses which were predominantly of IgG1 subtype were detected in the serum samples of the immunized mice and the IgG1/IgG2a ratio was significantly higher than that of the control group.Elevated secretory IgA(sIgA)was detected in the samples of small intestine,cecum and feces in the immunization group,especially in the small intestine samples,while no significant change in sIgA secretion was observed in the control group.The percentages of IL-17+CD4+T cells in spleen and mesenteric lymph nodes of the immunization group were significantly higher than those of the control group.Conclusions Oral immunization with Hp lysates in combination with adjuvant dmLT induced mucosal and systemic immune responses and enhanced the resistance to Hp colonization in BALB/c mice,which was associated with the significantly increased Th17 immune responses and Th2 polarization.This study provided reference for further evaluation of dmLT as a mucosal adjuvant in the development of recombinant protein vaccines against Hp infection.