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

疟疾仍然是世界许多地区发病率和死亡率的主要原因。脑型疟疾是疟疾感染最严重的表现形式，每年造成约30万人死亡，主要是非洲的幼儿。目前，抗疟疾药物是治疗HCM的唯一可用药物，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的人都得到了抗疟疾药物，但这种治疗未能防止死亡。此外，在HCM幸存者中，许多人表现出长期的神经缺陷，影响了他们的生活质量，在世界上一些最贫穷的国家造成了重大的社会经济负担。因此，迫切需要开发更好的治疗肥厚性心肌炎的方法。有一些证据表明，大脑内的炎症水平(神经炎症)可能有助于从HCM中恢复到次优水平。然而，由于我们只能从死于肥厚性脑病的人身上获得大脑，我们无法仅在人脑中研究导致肥厚性脑病发展的过程，也无法确定治疗方法如何促进肥厚性脑病的康复。因此，需要建立肥厚型心肌病的动物模型来识别和测试肥厚型心肌病的新治疗方法。小鼠实验性脑疟疾(ECM)模型是目前研究HCM最常用的模型，相应地，我们最近发现HCM和ECM的脑病理性质非常相似，验证了该模型用于开发HCM的新治疗方法。利用这一模型，我们发现，作为脑健康关键控制者的抗炎分子IL-33(IL-33)的应用，显著提高了已建立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似乎通过改善一种特定类型的神经炎症而起到保护作用，这种炎症是由一种名为炎症体的免疫复合体促进的。因此，这个项目的总体目标是确定rIL-33和炎性小体的抑制剂如何促进HCM的恢复。为了解决这个目标，在目标1中，我们将利用ECM模型来执行一系列分析，分析IL-33和炎性小体的抑制剂如何提高ECM的抗疟疾药物治疗的成功。具体地说，我们将研究这些治疗如何降低抗疟疾药物化疗后综合征的脑部病理水平和脑部炎症水平，提高存活率和降低神经功能障碍的严重程度。由于寄生虫与脑内皮细胞的黏附是HCM中的一个重要事件，在目标2中，我们将用寄生虫与人内皮细胞共培养系统的研究来补充ECM模型中的分析。利用这个系统，我们将研究IL-33和炎性小体抑制剂如何改善暴露在疟疾寄生虫和抗疟疾药物下的人脑内皮细胞的健康。最后，在这项研究的目标3中，我们将从感染了疟疾的人、患有疟疾但没有感染疟疾的人以及没有感染疟疾的人身上获得并进行血浆研究。我们还将从死于肥厚型心肌炎和其他死因的人身上获取大脑样本。通过对这些样本的分析，我们将评估全身和脑特异性IL-33水平、炎性小体激活、肥厚性心肌炎的发展和抗疟疾药物化疗的疗效之间的关系。总体而言，该项目的成功完成将展示使用IL-33和炎症小体抑制剂治疗如何改善CM的治疗和康复。这将优先发展临床试验，以评估IL-33和炎性小体抑制剂作为CM治疗方法的有效性。

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.