Targeting the IL-33-inflammasome axis in therapy for cerebral malaria

疟疾仍然是世界许多地区发病和死亡的主要原因。脑型疟疾（HCM）是疟疾感染的最严重表现，每年造成大约30万人死亡，主要是非洲的幼儿。目前，抗疟疾药物是HCM唯一可用的治疗方法，但这种治疗本身在15-25%的病例中不成功。事实上，大多数死于HCM的人都服用了抗疟疾药物，但治疗未能阻止死亡。此外，在HCM幸存者中，许多人表现出长期的神经功能缺损，影响他们的生活质量，在世界上一些最贫穷的国家造成重大的社会经济负担。因此，迫切需要开发更好的HCM治疗方法。有一些证据表明，大脑内的炎症水平（神经炎症）可能导致HCM的次优恢复。然而，由于我们只能从死于HCM的个体中获得大脑，我们无法仅在人类大脑中研究负责HCM发展的过程，也无法确定治疗改善HCM恢复的方法。因此，需要HCM的动物模型来鉴定和测试HCM的新疗法。小鼠实验性脑疟疾（ECM）模型是目前最常用的研究HCM的模型，相关的，我们最近已经表明，在HCM和ECM的脑病理学的性质是非常相似的，验证了新的治疗HCM的发展模型。使用该模型，我们发现，给予抗炎分子白细胞介素-IL-33（IL-33）（其作为脑健康的关键控制器而引起关注）显著提高了具有已建立ECM的小鼠的抗疟疾药物治疗的有效性。重要的是，我们发现IL-33似乎是通过改善一种特定类型的神经炎症来保护的，这种神经炎症是由一种称为炎性小体的免疫复合物促进的。因此，本项目的总体目标是确定rIL-33和炎性体抑制剂改善HCM恢复的方式。为了实现这一目标，在目标1中，我们将利用ECM模型进行一系列分析，研究IL-33和炎性体抑制剂如何改善ECM抗疟疾药物治疗的成功率。具体来说，我们将研究治疗如何降低抗疟疾药物化疗后脑内的脑病理学和脑炎症水平，提高生存率并降低神经功能缺损的严重程度。由于寄生虫粘附到脑内皮细胞是HCM中的重要事件，因此在目标2中，我们将通过寄生虫-人内皮细胞共培养系统中的研究来补充ECM模型中的分析。使用这个系统，我们将研究IL-33和炎性体抑制剂如何改善暴露于疟疾寄生虫和抗疟疾药物的人脑内皮细胞的健康。最后，在本研究的目标3中，我们将从HCM患者、患有疟疾但未患有HCM的患者以及未感染疟疾的患者中获得血浆并进行研究。我们还将从死于HCM的个体和其他死因的个体中获得大脑样本。通过分析这些样本，我们将评估全身和脑特异性IL-33水平，炎性小体激活，HCM的发展和HCM的抗疟疾药物化疗的结果之间的关系。总的来说，该项目的成功完成将证明IL-33和炎性体抑制剂的治疗如何改善CM的治疗和恢复。这将优先发展临床试验，以评估IL-33和炎性体抑制剂作为CM治疗的有效性。

Malaria continues to be a major cause of morbidity and mortality in many regions of the world. Cerebral malaria (HCM) is the most severe manifestation of malaria infection, being responsible for the death of approximately 300,000 people, mainly young children in Africa, each year. Currently anti-malarial drugs are the only available treatment for HCM but by itself such treatment is unsuccessful in 15-25% of cases. Indeed, the majority of individuals that die from HCM are given anti-malarial drugs but the treatment fails to prevent death. Moreover, in the individuals that survive HCM, many exhibit long-lasting neurological deficits that impact on their quality of life creating a significant socio-economic burden in some of the poorest countries in the world. Thus, there is an urgent need to develop better treatments for HCM. There is some evidence that the level of inflammation within the brain (neuroinflammation), may contribute to the sub-optimal recovery from HCM. However, as we are only able to obtain brains from individuals that died of HCM, we are unable to study solely in human brains the processes that are responsible for development of HCM nor can we identify the ways through which treatments improve recovery from HCM. Thus, animal models of HCM are required to identify and test new treatments for HCM. The murine experimental cerebral malaria (ECM) model is currently the most frequently utilised model to study HCM and, relevantly, we have recently shown that the nature of brain pathology in HCM and ECM are very similar, validating the model for development of new treatments for HCM. Using this model, we have found that administration of the anti-inflammatory molecule interleukin-IL-33 (IL-33), which is garnering interest as a critical controller of brain health, significantly improves the effectiveness of anti-malarial drug treatment of mice with established ECM. Importantly, we have found that IL-33 appears to be protective through ameliorating a specific type of neuroinflammation that is promoted by an immune complex called the inflammasome. Consequently, the overall aim of this project is to define the way in which rIL-33 and inhibitors of the inflammasome improve the recovery from HCM.To address this aim, in objective 1 we will utilise the ECM model to perform a series of analyses of how IL-33 and inhibitors of the inflammasome improve the success of anti-malarial drug treatment of ECM. Specifically, we will examine how the treatments reduce the level of cerebral pathology and cerebral inflammation within the brain post-anti-malarial drug chemotherapy of the syndrome, improving survival and reducing the severity of neurological deficits. Because parasite-adhesion to cerebral endothelial cells is an important event in HCM, in objective 2 we will complement the analyses in the ECM model with studies in a parasite-human endothelial cell co-culture system. Using this system we will examine how IL-33 and inflammasome inhibitors improve the health of human brain endothelial cells exposed to malaria parasites and anti-malarial drugs. Finally, in objective 3 of the study we will obtain and perform studies in plasma from individuals with HCM, individuals with malaria but who did not have HCM, and from individuals that were not infected with malaria. We will also obtain brain samples from individuals that died of HCM and from individuals with other causes of death. By analysing these samples we will assess the relationship between systemic and brain-specific IL-33 levels, inflammasome activation, and the development of HCM and the outcome of anti-malarial drug chemotherapy of HCM. Overall, the successful completion of this project will demonstrate how therapy with IL-33 and inflammasome inhibitors can improve the treatment and recovery from CM. This will prioritise the development of clinical trials to assess the effectiveness of IL-33 and inflammasome inhibitors as treatments for CM.