Recombinant TgHSP70 Immunization Protects against Toxoplasma gondii Brain Cyst Formation by Enhancing Inducible Nitric Oxide Expression.
Recombinant TgHSP70 Immunization Protects against Toxoplasma gondii Brain Cyst Formation by Enhancing Inducible Nitric Oxide Expression.
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DOI：
10.3389/fcimb.2017.00142
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发表时间：
2017
影响因子：
5.7
通讯作者：
Silva NM
中科院分区：
文献类型：
--
作者：
Czarnewski P;Araújo ECB;Oliveira MC;Mineo TWP;Silva NM
众所周知，弓形虫会导致人类和动物先天性感染，并导致免疫功能低下的个体患上严重疾病；因此，开发针对该寄生虫的疫苗非常有必要。在应激条件下，弓形虫表达高免疫原性热休克蛋白 70 (TgHSP70)。在这里，我们评估了 rTgHSP70 免疫联合明矾对口腔 ME-49 弓形虫感染的保护效果及其机制。据观察，无论是否使用佐剂，用rTgHSP70或吸附在明矾中的rTgHSP70免疫的小鼠大脑中囊肿数量显着减少，这与器官中iNOS+细胞数量增加相关。事实上，离体实验表明，用 rTgHSP70 预刺激的腹膜巨噬细胞呈现出 NO 产量增加和寄生虫杀伤增强，并且该蛋白质能够直接刺激 B 细胞产生抗体。此外，rTgHSP70 免疫可导致全身性高特异性抗体滴度和混合 IgG1/IgG2a 反应，其中以 IgG1 产生为主。尽管如此，观察到用rTgHSP70免疫血清预处理寄生虫不能控制弓形虫内化和NIH成纤维细胞的复制，腹膜鼠巨噬细胞和抗rTgHSP70抗体都不能通过补体介导的裂解杀死弓形虫，这表明这些机制对于耐药性并不重要。有趣的是，当与明矾联合使用时，rTgHSP70 免疫能够减少受感染小鼠大脑中的炎症，并同时减少血清中的抗 rTgHSP70 免疫复合物。总之，rTgHSP70免疫诱导大量iNOS表达并减少脑寄生，这表明脑中iNOS表达和NO产生是TgHSP70免疫诱导的保护机制，因此rTgHSP70可以成为弓形体病疫苗开发的良好候选者。
Toxoplasma gondii is known to cause congenital infection in humans and animals and severe disease in immunocompromised individuals; consequently development of vaccines against the parasite is highly necessary. Under stress conditions, T. gondii expresses the highly immunogenic heat shock protein 70 (TgHSP70). Here, we assessed the protective efficacy of rTgHSP70 immunization combined with Alum in oral ME-49 T. gondii infection and the mechanisms involved on it. It was observed that immunized mice with rTgHSP70 or rTgHSP70 adsorbed in Alum presented a significantly reduced number of cysts in the brain that was associated with increased iNOS+ cell numbers in the organ, irrespective the use of the adjuvant. Indeed, ex vivo experiments showed that peritoneal macrophages pre-stimulated with rTgHSP70 presented increased NO production and enhanced parasite killing, and the protein was able to directly stimulate B cells toward antibody producing profile. In addition, rTgHSP70 immunization leads to high specific antibody titters systemically and a mixed IgG1/IgG2a response, with predominance of IgG1 production. Nonetheless, it was observed that the pretreatment of the parasite with rTgHSP70 immune sera was not able to control T. gondii internalization and replication by NIH fibroblast neither peritoneal murine macrophages, nor anti-rTgHSP70 antibodies were able to kill T. gondii by complement-mediated lysis, suggesting that these mechanisms are not crucial to resistance. Interestingly, when in combination with Alum, rTgHSP70 immunization was able to reduce inflammation in the brain of infected mice and in parallel anti-rTgHSP70 immune complexes in the serum. In conclusion, immunization with rTgHSP70 induces massive amounts of iNOS expression and reduced brain parasitism, suggesting that iNOS expression and consequently NO production in the brain is a protective mechanism induced by TgHSP70 immunization, therefore rTgHSP70 can be a good candidate for vaccine development against toxoplasmosis.