New Plasmodium Strategies to Modulate Inflammation

项目摘要/摘要 疟原虫血液期感染的特征是急性宿主炎症。 高水平的促炎细胞因子的反应，这些细胞因子参与了 疾病。我们对约氏假单胞菌的一种可溶性活性进行了分子表征。 和恶性疟原虫诱导小鼠前列腺素E_2、肿瘤坏死因子和IL-6的释放 树突状细胞。粒度分级和质谱联用鉴定次黄嘌呤为 负责这些活动的分子。然而，我们观察到次黄嘌呤只是 当它被降解为尿酸时，它是活跃的。添加次黄嘌呤的抑制剂别嘌醇 降解，抑制约氏疟原虫感染红细胞诱导的细胞因子的产生。 此外，尿酸酶处理抑制树突状细胞分泌肿瘤坏死因子，提示尿酸是 本活动的最终调解人。尿酸是众所周知的免疫反应调节剂，因为它 痛风的病原体已被确定为免疫系统的危险信号。 尿酸晶体对肿瘤坏死因子的分泌有双重作用，激活或抑制肿瘤坏死因子 根据条件的不同，我们还发现了约氏假丝酵母衍生的次黄嘌呤的双重作用 树突状细胞对肿瘤坏死因子分泌的降解。我们还观察到，使用 别嘌醇可引起感染小鼠脑内肿瘤坏死因子和肿瘤坏死因子-α的升高 在其他不敏感的小鼠中产生脑型疟疾，表明次黄嘌呤 退化可以预防小鼠的脑型疟疾。我们还观察到IL-12的增加，以及 降低小鼠脾组织中IL-10和IL-6的含量。 我们打算表征次黄嘌呤在疟疾感染过程中的降解， 产生的尿酸和活性氧物种，以及在先天和适应性中的作用 对疾病及其相关病理的免疫反应。作为细胞因子对 疟疾影响先天免疫反应、T细胞反应和 脑型疟疾的发生，我们将研究次黄嘌呤降解在这些过程中的作用 在小鼠感染疟疾的过程中。我们还将描述次黄嘌呤的作用 人免疫细胞对恶性疟原虫体外反应的降解。 初步研究结果表明，这一途径在肿瘤坏死因子和白介素1β的释放中起重要作用 对感染恶性疟原虫的红细胞产生免疫应答。 因为疟疾引起的炎症反应是导致大部分病理改变的原因 与疟疾感染有关，包括死亡，了解它对于 开发有效的治疗方法。

PROJECT SUMMARY/ABSTRACT Plasmodium blood-stage infection is characterized by an acute host inflammatory response with high levels of pro-inflammatory cytokines, which contribute to the pathology of the disease. We have performed the molecular characterization of a soluble activity from P. yoelii and P. falciparum that induces the release of prostaglandin E2, TNF and IL-6 from mouse dendritic cells. Size fractionation followed by mass spectrometry identified hypoxanthine as the molecule responsible for these activities. However, we observed that hypoxanthine was only active when it is degraded into uric. Addition of allopurinol, an inhibitor of hypoxanthine degradation, inhibited the production of cytokines induced by P. yoelii-infected erythrocytes. Also uricase treatment inhibited TNF secretion by dendritic cells, suggesting that uric acid is the final mediator of this activity. Uric acid is a well-known modulator of immune responses, as it is the causative agent of gout and has been identified as a danger signal for the immune system. Uric acid crystals can have a dual role on the secretion of TNF activating or inhibiting it depending on the conditions, we also found a dual role of P. yoelii-derived hypoxanthine degradation on TNF secretion by dendritic cells. We also observed that treatment with allopurinol results in increased TNF and LT-alpha in the brain of infected mice and in the generation of cerebral malaria in otherwise non-susceptible mice, suggesting that hypoxanthine degradation prevents cerebral malaria in mice. We also observed an increase in IL-12, and a decrease in IL-10 and IL-6 in spleens of these mice. We intend to characterize hypoxanthine degradation during malaria infections, the role of generated uric acid and reactive oxygen species, and the effects in the innate and adaptive immune response to the disease and its assoicated pathologies. As cytokine responses to malaria influence the outcome of innate immune responses, T cell responses and the generation of cerebral malaria, we will investigate the role of hypoxanthine degradation in these processes during malaria infections in mice. We will also characterize the role of hypoxanthine degradation in the response of human immune cells to Plasmodium falciparum in vitro. Preliminary Results already show a significant role of this pathway in TNF and IL1beta release in response to P. falciparum infected erythrocytes. As the malaria-induced inflammatory response contributes to most of the pathology associated with malaria infections, including death, its understanding is essential for the development of effective treatments.