Elphinstone Robyn E, Besla Rickvinder, Shikatani Eric A, Lu Ziyue, Hausladen Alfred, Davies Matthew, Robbins Clinton S, Husain Mansoor, Stamler Jonathan S, Kain Kevin C
Sandra Rotman Centre for Global Health, University Health Network, University of Toronto, Toronto, ON, Canada.
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
Infect Immun. 2017 Aug 18;85(9). doi: 10.1128/IAI.00371-17. Print 2017 Sep.
Artesunate remains the mainstay of treatment for cerebral malaria, but it is less effective in later stages of disease when the host inflammatory response and blood-brain barrier integrity dictate clinical outcomes. Nitric oxide (NO) is an important regulator of inflammation and microvascular integrity, and impaired NO bioactivity is associated with fatal outcomes in malaria. Endogenous NO bioactivity in mammals is largely mediated by -nitrosothiols (SNOs). Based on these observations, we hypothesized that animals deficient in the SNO-metabolizing enzyme, -nitrosoglutathione reductase (GSNOR), which exhibit enhanced -nitrosylation, would have improved outcomes in a preclinical model of cerebral malaria. GSNOR knockout (KO) mice infected with ANKA had significantly delayed mortality compared to WT animals ( < 0.0001), despite higher parasite burdens ( < 0.01), and displayed markedly enhanced survival versus the wild type (WT) when treated with the antimalarial drug artesunate (77% versus 38%; < 0.001). Improved survival was associated with higher levels of protein-bound NO, decreased levels of CD4 and CD8 T cells in the brain, improved blood-brain barrier integrity, and improved coma scores, as well as higher levels of gamma interferon. GSNOR KO animals receiving WT bone marrow had significantly reduced survival following ANKA infection compared to those receiving KO bone barrow ( < 0.001). Reciprocal transplants established that survival benefits of GSNOR deletion were attributable primarily to the T cell compartment. These data indicate a role for GSNOR in the host response to malaria infection and suggest that strategies to disrupt its activity will improve clinical outcomes by enhancing microvascular integrity and modulating T cell tissue tropism.
青蒿琥酯仍然是治疗脑型疟疾的主要药物，但在疾病后期，当宿主炎症反应和血脑屏障完整性决定临床结果时，其疗效会降低。一氧化氮（NO）是炎症和微血管完整性的重要调节因子，NO生物活性受损与疟疾的致命结局相关。哺乳动物体内的内源性NO生物活性主要由亚硝基硫醇（SNOs）介导。基于这些观察结果，我们推测，缺乏SNO代谢酶亚硝基谷胱甘肽还原酶（GSNOR）且表现出亚硝基化增强的动物，在脑型疟疾的临床前模型中会有更好的预后。与野生型动物相比，感染ANKA的GSNOR基因敲除（KO）小鼠死亡率显著延迟（P<0.0001），尽管寄生虫负荷更高（P<0.01），并且在用抗疟药物青蒿琥酯治疗时，与野生型（WT）相比，其存活率显著提高（77%对38%；P<0.001）。存活率的提高与蛋白结合NO水平升高、脑中CD4和CD8 T细胞水平降低、血脑屏障完整性改善、昏迷评分改善以及γ干扰素水平升高有关。与接受KO骨髓的动物相比，接受野生型骨髓的GSNOR KO动物在感染ANKA后存活率显著降低（P<0.001）。相互移植实验表明，GSNOR缺失的存活益处主要归因于T细胞区室。这些数据表明GSNOR在宿主对疟疾感染的反应中发挥作用，并表明破坏其活性的策略将通过增强微血管完整性和调节T细胞组织嗜性来改善临床结果。
