Data_Sheet_1_Neospora caninum Activates p38 MAPK as an Evasion Mechanism against Innate Immunity.PDF

Due to the high prevalence and economic impact of neosporosis, the development of safe and effective vaccines and therapies against this parasite has been a priority in the field and is crucial to limit horizontal and vertical transmission in natural hosts. Limited data is available regarding factors that regulate the immune response against this parasite and such knowledge is essential in order to understand Neospora caninum induced pathogenesis. Mitogen-activated protein kinases (MAPKs) govern diverse cellular processes, including growth, differentiation, apoptosis, and immune-mediated responses. In that sense, our goal was to understand the role of MAPKs during the infection by N. caninum. We found that p38 phosphorylation was quickly triggered in macrophages stimulated by live tachyzoites and antigen extracts, while its chemical inhibition resulted in upregulation of IL-12p40 production and augmented B7/MHC expression. In vivo blockade of p38 resulted in an amplified production of cytokines, which preceded a reduction in latent parasite burden and enhanced survival against the infection. Additionally, the experiments indicate that the p38 activation is induced by a mechanism that depends on GPCR, PI3K and AKT signaling pathways, and that the phenomena here observed is distinct that those induced by Toxoplasma gondii’s GRA24 protein. Altogether, these results showed that N. caninum manipulates p38 phosphorylation in its favor, in order to downregulate the host’s innate immune responses. Additionally, those results infer that active interference in this signaling pathway may be useful for the development of a new therapeutic strategy against neosporosis.

鉴于新孢子虫病的高发病率及其对经济的巨大影响，开发针对此寄生虫的安全有效疫苗和治疗策略一直是该领域的研究重点，对于限制自然宿主中的水平传播和垂直传播至关重要。关于调节针对此寄生虫免疫反应的因素数据有限，此类知识对于理解犬新孢子虫引起的致病机制至关重要。丝裂原活化蛋白激酶（MAPKs）调控着多种细胞过程，包括生长、分化、凋亡以及免疫介导的反应。在此意义上，我们的目标是理解MAPKs在犬新孢子虫感染过程中的作用。我们发现，活化的速殖子在刺激巨噬细胞时迅速触发p38磷酸化，而其化学抑制则导致IL-12p40产生上调和B7/MHC表达增强。体内p38阻断导致细胞因子产生增加，这预示着潜伏寄生虫负担减少，并增强了对抗感染存活率。此外，实验表明，p38激活是由依赖于G蛋白偶联受体、PI3K和AKT信号通路机制的诱导，而此处观察到的现象与弓形虫GRA24蛋白诱导的现象不同。总之，这些结果表明犬新孢子虫通过操纵p38磷酸化以有利于自身，从而下调宿主的先天免疫反应。此外，这些结果推断，积极干扰这一信号通路可能有助于开发针对新孢子虫病的新治疗策略。