Binding of Plasmodium falciparum to CD36 can be shielded by the glycocalyx
Binding of Plasmodium falciparum to CD36 can be shielded by the glycocalyx
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DOI：
10.1186/s12936-017-1844-6
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发表时间：
2017-05-10
期刊：
影响因子：
3
通讯作者：
Staalso, Trine
中科院分区：
文献类型：
--
作者：
Hempel, Casper;Wang, Christian William;Staalso, Trine
背景：恶性疟原虫感染的红细胞由于表面表达的寄生虫蛋白和内皮受体的相互作用而在微循环中隔离。内皮细胞被一种富含碳水化合物的糖萼所覆盖，它可以抵御不必要的白细胞粘连。方法：分别用叠氮糖和阳离子铁蛋白检测O-糖蛋白和带负电荷的蛋白多糖来跟踪体外培养的糖基化红细胞的生长。在转人CD36的中国仓鼠卵巢(CHO)细胞上筛选恶性疟原虫克隆株FCR3/IT。结果：通过叠氮多糖代谢标记和电子显微镜观察阳离子铁蛋白与细胞表面的结合，结果表明，在培养的4天，CHO细胞与CD36的细胞黏附量增加。这一过程的功能重要性在通过使用CD36转染的CHO细胞进行结合分析中得到了解决。尽管CD36的表达稳定，但与CD36的抗体结合受到抑制。选择CD36结合的恶性疟原虫在培养的第一天就能识别CHO细胞上的CD36，但在2-4天后就失去了结合。结论：内皮细胞糖萼在体外影响寄生虫的细胞黏附，这一作用以前被忽视。先前报道的在实验性疟疾过程中糖萼的丢失可能通过允许感染的红细胞和内皮受体之间的密切相互作用而在疟疾并发症的发病机制中发挥重要作用。
Background: Plasmodium falciparum-infected erythrocytes sequester in the microcirculation due to interaction between surface-expressed parasite proteins and endothelial receptors. Endothelial cells are covered in a carbohydrate-rich glycocalyx that shields against undesired leukocyte adhesion. It was investigated if the cellular glycocalyx affects the binding of P. falciparum-infected erythrocytes to CD36 in vitro.Methods: Glycocalyx growth was followed in vitro by using azido sugars and cationized ferritin detecting O-glycoproteins and negatively charged proteoglycans, respectively. P. falciparum (clone FCR3/IT) was selected on Chinese hamster ovary (CHO) cells transfected with human CD36. Cytoadhesion to CHO CD36 at 1-4 days after seeding was quantified by using a static binding assay.Results: The glycocalyx thickness of CHO cells increased during 4 days in culture as assessed by metabolic labelling of glycans with azido sugars and with electron microscopy studying the binding of cationized ferritin to cell surfaces. The functional importance of this process was addressed in binding assays by using CHO cells transfected with CD36. In parallel with the maturation of the glycocalyx, antibody-binding to CD36 was inhibited, despite stable expression of CD36. P. falciparum selected for CD36-binding recognized CD36 on CHO cells on the first day in culture, but the binding was lost after 2-4 days.Conclusion: The endothelial glycocalyx affects parasite cytoadhesion in vitro, an effect that has previously been ignored. The previously reported loss of glycocalyx during experimental malaria may play an important role in the pathogenesis of malaria complications by allowing the close interaction between infected erythrocytes and endothelial receptors.