Department of Microbiology & Immunology and Infectious Diseases, Albert Einstein College of Medicine, Bronx, NY, USA.
Seattle Biomedical Research Institute, Seattle, WA, USA.
Malar J. 2020 Oct 21;19(1):376. doi: 10.1186/s12936-020-03447-7.
Cerebral malaria (CM) is associated with morbidity and mortality despite the use of potent anti-malarial agents. Brain endothelial cell activation and dysfunction from oxidative and inflammatory host responses and products released by Plasmodium falciparum-infected erythrocytes (IE), are likely the major contributors to the encephalopathy, seizures, and brain swelling that are associated with CM. The development of adjunctive therapy to reduce the pathological consequences of host response pathways could improve outcomes. A potentially protective role of the nuclear factor E2-related factor 2 (NRF2) pathway, which serves as a therapeutic target in brain microvascular diseases and central nervous system (CNS) inflammatory diseases such as multiple sclerosis was tested to protect endothelial cells in an in vitro culture system subjected to tumour necrosis factor (TNF) or infected red blood cell exposure. NRF2 is a transcription factor that mediates anti-oxidant and anti-inflammatory responses.
To accurately reflect clinically relevant parasite biology a unique panel of parasite isolates derived from patients with stringently defined CM was developed. The effect of TNF and these parasite lines on primary human brain microvascular endothelial cell (HBMVEC) activation in an in vitro co-culture model was tested. HBMVEC activation was measured by cellular release of IL6 and nuclear translocation of NFκB. The transcriptional and functional effects of dimethyl fumarate (DMF), an FDA approved drug which induces the NRF2 pathway, on host and parasite induced HBMVEC activation was characterized. In addition, the effect of DMF on parasite binding to TNF stimulated HBMVEC in a semi-static binding assay was examined.
Transcriptional profiling demonstrates that DMF upregulates the NRF2-Mediated Oxidative Stress Response, ErbB4 Signaling Pathway, Peroxisome Proliferator-activated Receptor (PPAR) Signaling and downregulates iNOS Signaling and the Neuroinflammation Signaling Pathway on TNF activated HBMVEC. The parasite lines derived from eight paediatric CM patients demonstrated increased binding to TNF activated HBMVEC and varied in their binding and activation of HBMVEC. Overall DMF reduced both TNF and CM derived parasite activation of HBMVEC.
These findings provide evidence that targeting the NRF2 pathway in TNF and parasite activated HBMVEC mediates multiple protective pathways and may represent a novel adjunctive therapy to improve infection outcomes in CM.
尽管使用了有效的抗疟药物，脑疟疾（CM）仍与发病率和死亡率有关。氧化和炎症宿主反应以及疟原虫感染红细胞（IE）释放的产物引起的脑内皮细胞激活和功能障碍，可能是与 CM 相关的脑病、癫痫发作和脑水肿的主要原因。开发辅助治疗方法来减少宿主反应途径的病理后果可能会改善结局。核因子 E2 相关因子 2（NRF2）途径具有保护作用，作为脑微血管疾病和中枢神经系统（CNS）炎症性疾病（如多发性硬化症）的治疗靶点，在体外培养系统中用肿瘤坏死因子（TNF）或感染的红细胞暴露来测试保护内皮细胞。NRF2 是一种转录因子，介导抗氧化和抗炎反应。
为了准确反映临床上相关的寄生虫生物学，从严格定义的 CM 患者中开发了一组独特的寄生虫分离株。在体外共培养模型中，测试 TNF 和这些寄生虫系对原代人脑微血管内皮细胞（HBMVEC）激活的影响。通过细胞因子 IL6 的释放和 NFκB 的核易位来测量 HBMVEC 的激活。用二甲基富马酸（DMF）（一种美国食品和药物管理局批准的药物，可诱导 NRF2 途径）来描述其对宿主和寄生虫诱导的 HBMVEC 激活的转录和功能影响。此外，还检查了 DMF 在半静态结合测定中对 TNF 刺激的 HBMVEC 上寄生虫结合的影响。
转录谱分析表明，DMF 上调了 NRF2 介导的氧化应激反应、ErbB4 信号通路、过氧化物酶体增殖物激活受体（PPAR）信号通路，并下调了 TNF 激活的 HBMVEC 中的 iNOS 信号通路和神经炎症信号通路。从八名小儿 CM 患者中分离出的寄生虫株显示出与 TNF 激活的 HBMVEC 结合增加，并在与 HBMVEC 的结合和激活方面存在差异。总体而言，DMF 减少了 TNF 和 CM 衍生的寄生虫对 HBMVEC 的激活。
这些发现为靶向 TNF 和寄生虫激活的 HBMVEC 中的 NRF2 途径提供了证据，该途径介导多种保护途径，可能代表一种改善 CM 感染结局的新型辅助治疗方法。
