Franke-Fayard Blandine, Janse Chris J, Cunha-Rodrigues Margarida, Ramesar Jai, Büscher Philippe, Que Ivo, Löwik Clemens, Voshol Peter J, den Boer Marion A M, van Duinen Sjoerd G, Febbraio Maria, Mota Maria M, Waters Andrew P
Department of Parasitology, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.
Proc Natl Acad Sci U S A. 2005 Aug 9;102(32):11468-73. doi: 10.1073/pnas.0503386102. Epub 2005 Jul 28.
Sequestration of malaria-parasite-infected erythrocytes in the microvasculature of organs is thought to be a significant cause of pathology. Cerebral malaria (CM) is a major complication of Plasmodium falciparum infections, and PfEMP1-mediated sequestration of infected red blood cells has been considered to be the major feature leading to CM-related pathology. We report a system for the real-time in vivo imaging of sequestration using transgenic luciferase-expressing parasites of the rodent malaria parasite Plasmodium berghei. These studies revealed that: (i) as expected, lung tissue is a major site, but, unexpectedly, adipose tissue contributes significantly to sequestration, and (ii) the class II scavenger-receptor CD36 to which PfEMP1 can bind is also the major receptor for P. berghei sequestration, indicating a role for alternative parasite ligands, because orthologues of PfEMP1 are absent from rodent malaria parasites, and, importantly, (iii) cerebral complications still develop in the absence of CD36-mediated sequestration, dissociating parasite sequestration from CM-associated pathology. Real-time in vivo imaging of parasitic processes may be used to evaluate the molecular basis of pathology and develop strategies to prevent pathology.
疟原虫感染的红细胞在器官微血管中的滞留被认为是病理变化的一个重要原因。脑型疟疾(CM)是恶性疟原虫感染的主要并发症,而PfEMP1介导的感染红细胞滞留被认为是导致CM相关病理变化的主要特征。我们报告了一种利用表达荧光素酶的转基因啮齿动物疟原虫伯氏疟原虫对滞留进行实时体内成像的系统。这些研究表明:(i)正如预期的那样,肺组织是主要部位,但出乎意料的是,脂肪组织对滞留也有显著贡献;(ii)PfEMP1可以结合的II类清道夫受体CD36也是伯氏疟原虫滞留的主要受体,这表明存在替代寄生虫配体的作用,因为啮齿动物疟原虫中不存在PfEMP1的直系同源物,而且重要的是,(iii)在没有CD36介导的滞留情况下仍会出现脑部并发症,这将寄生虫滞留与CM相关病理变化分离开来。对寄生过程的实时体内成像可用于评估病理变化的分子基础并制定预防病理变化的策略。