Institut Necker Enfants Malades, INSERM U1151, CNRS UMR8253, Paris, France.
Université Paris Descartes, Paris, France.
PLoS Pathog. 2018 Apr 9;14(4):e1006981. doi: 10.1371/journal.ppat.1006981. eCollection 2018 Apr.
Purpura fulminans is a deadly complication of Neisseria meningitidis infections due to extensive thrombosis of microvessels. Although a Disseminated Intra-vascular Coagulation syndrome (DIC) is frequently observed during Gram negative sepsis, it is rarely associated with extensive thrombosis like those observed during meningococcemia, suggesting that the meningococcus induces a specific dysregulation of coagulation. Another specific feature of N. meningitidis pathogenesis is its ability to colonize microvessels endothelial cells via type IV pili. Importantly, endothelial cells are key in controlling the coagulation cascade through the activation of the potent anticoagulant Protein C (PC) thanks to two endothelial cell receptors among which the Endothelial Protein C Receptor (EPCR). Considering that congenital or acquired deficiencies of PC are associated with purpura fulminans, we hypothesized that a defect in the activation of PC following meningococcal adhesion to microvessels is responsible for the thrombotic events observed during meningococcemia. Here we showed that the adhesion of N. meningitidis on endothelial cells results in a rapid and intense decrease of EPCR expression by inducing its cleavage in a process know as shedding. Using siRNA experiments and CRISPR/Cas9 genome edition we identified ADAM10 (A Disintegrin And Metalloproteinase-10) as the protease responsible for this shedding. Surprisingly, ADAM17, the only EPCR sheddase described so far, was not involved in this process. Finally, we showed that this ADAM10-mediated shedding of EPCR induced by the meningococcal interaction with endothelial cells was responsible for an impaired activation of Protein C. This work unveils for the first time a direct link between meningococcal adhesion to endothelial cells and a severe dysregulation of coagulation, and potentially identifies new therapeutic targets for meningococcal purpura fulminans.
暴发性紫癜是脑膜炎奈瑟菌感染的一种致命并发症，其原因是微血管广泛血栓形成。虽然在革兰氏阴性菌脓毒症中经常观察到弥散性血管内凝血综合征（DIC），但它很少与脑膜炎球菌血症中观察到的广泛血栓形成有关，这表明脑膜炎球菌诱导了特定的凝血失调。脑膜炎奈瑟菌发病机制的另一个特定特征是其通过 IV 型菌毛定植微血管内皮细胞的能力。重要的是，内皮细胞通过激活强效抗凝蛋白 C（PC）在控制凝血级联反应中起着关键作用，这要归功于内皮细胞受体中的两种，其中包括内皮蛋白 C 受体（EPCR）。鉴于先天性或获得性 PC 缺乏与暴发性紫癜有关，我们假设脑膜炎球菌黏附于微血管后 PC 激活缺陷是导致脑膜炎球菌血症中观察到的血栓形成事件的原因。在这里，我们表明，脑膜炎奈瑟菌黏附在内皮细胞上会导致 EPCR 表达迅速而强烈地下调，这是一种称为脱落的过程。通过 siRNA 实验和 CRISPR/Cas9 基因组编辑，我们确定 ADAM10（一种解整合素和金属蛋白酶-10）是负责这种脱落的蛋白酶。令人惊讶的是，迄今为止唯一描述的 EPCR 脱落酶 ADAM17 并未参与该过程。最后，我们表明，这种由脑膜炎球菌与内皮细胞相互作用诱导的 ADAM10 介导的 EPCR 脱落导致蛋白 C 激活受损。这项工作首次揭示了脑膜炎球菌黏附在内皮细胞上与严重凝血失调之间的直接联系，并可能为脑膜炎球菌暴发性紫癜确定新的治疗靶点。
