1 Biological and Soft Systems, Department of Physics, University of Cambridge , J J Thomson Avenue, Cambridge CB3 0HE , UK.
2 Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università di Napoli Federico II , Napoli , Italy.
J R Soc Interface. 2018 Dec 21;15(149):20180773. doi: 10.1098/rsif.2018.0773.
Malaria is associated with significant microcirculation disorders, especially when the infection reaches its severe stage. This can lead to a range of fatal conditions, from cerebral malaria to multiple organ failure, of not fully understood pathogenesis. It has recently been proposed that a breakdown of the glycocalyx, the carbohydrate-rich layer lining the vascular endothelium, plays a key role in severe malaria, but direct evidence supporting this hypothesis is still lacking. Here, the interactions between Plasmodium falciparum infected red blood cells ( PfRBCs) and endothelial glycocalyx are investigated by developing an in vitro, physiologically relevant model of human microcirculation based on microfluidics. Impairment of the glycocalyx is obtained by enzymatic removal of sialic acid residues, which, due to their terminal location and net negative charge, are implicated in the initial interactions with contacting cells. We show a more than twofold increase of PfRBC adhesion to endothelial cells upon enzymatic treatment, relative to untreated endothelial cells. As a control, no effect of enzymatic treatment on healthy red blood cell adhesion is found. The increased adhesion of PfRBCs is also associated with cell flipping and reduced velocity as compared to the untreated endothelium. Altogether, these results provide a compelling evidence of the increased cytoadherence of PfRBCs to glycocalyx-impaired vascular endothelium, thus supporting the advocated role of glycocalyx disruption in the pathogenesis of this disease.
疟疾与显著的微循环障碍有关，尤其是当感染达到严重阶段时。这可能导致一系列致命情况，从脑疟疾到多器官衰竭，其发病机制尚未完全了解。最近有人提出，糖萼（血管内皮衬里富含碳水化合物的层）的破裂在严重疟疾中起着关键作用，但支持这一假说的直接证据仍然缺乏。在这里，通过开发基于微流控的体外生理相关的人类微循环模型，研究了恶性疟原虫感染的红细胞（PfRBC）与内皮糖萼之间的相互作用。通过酶去除唾液酸残基来破坏糖萼，由于其末端位置和净负电荷，唾液酸残基与接触细胞的初始相互作用有关。与未处理的内皮细胞相比，我们发现酶处理后 PfRBC 与内皮细胞的粘附增加了两倍以上。作为对照，未发现酶处理对健康红细胞粘附有任何影响。与未处理的内皮细胞相比，PfRBC 的粘附增加还与细胞翻转和速度降低有关。总之，这些结果提供了令人信服的证据，表明 PfRBC 对糖萼受损血管内皮的细胞黏附增加，从而支持糖萼破坏在该疾病发病机制中的作用。
