Role of T-cell derived prothrombin in septicemia

丝氨酸蛋白酶凝血酶除止血外，还参与许多生理功能，包括血管生成、胚胎发生、肿瘤形成和炎症。血清凝血酶原水平来源于肝脏的蛋白质合成，然而凝血酶原(F2)基因在其他组织中的表达已被证明发生在胚胎发育过程中。虽然凝血酶如何在各种病理中发挥其关键作用已有相当多的见解，但对肝外凝血酶原表达的(病理)生理功能知之甚少。通过建立骨髓嵌合动物，在其中凝血酶原被选择性地消融在骨髓室，我们最近观察到骨髓源性凝血酶原在败血症中的关键功能。尽管血清凝血酶原水平没有改变，但去除骨髓来源细胞中凝血酶原的特异性表达导致了败血症患者更高的存活率。为了鉴定骨髓中表达凝血酶原的细胞类型(S)，我们采用了磁性(MACS)和荧光激活细胞分选(FAC)，然后基于从新设计的转基因小鼠模型(称为D-Insight)中获得的纯化细胞进行光度测定，在该模型中，内源性凝血酶原的表达被荧光素酶报告分子标记。用MACS和FACS分离不同的骨髓来源细胞群，然后用发光法，我们鉴定了抗原经历过的CD4和CD8阳性T细胞表达凝血酶原。我们现在想要破译骨髓来源的凝血酶原表达在调节败血症中的神秘功能作用。为此，我们将利用组织特异性凝血酶原基因敲除小鼠，并将其与体内和体外功能研究、组学和药理学方法相结合，以揭示T细胞来源的凝血酶原在败血症中的作用。阐明凝血成分除止血功能外的非规范功能，对于阐明它们在非常常见和最具破坏性疾病的病理生理学中的作用至关重要。这也可能有助于寻找新的途径来确定抗击败血症的合理化目标，败血症是全球相当大比例受影响患者的一种最新致命疾病。

The serine protease thrombin is involved in a number of physiological functions beyond hemostasis including angiogenesis, embryogenesis, tumorigenesis and inflammation. Serum levels of prothrombin derive from protein synthesis in the liver, yet expression of the prothrombin (F2) gene in a variety of other tissues has been demonstrated to occur during embryogenesis. While considerable insights have been obtained on how thrombin exerts its crucial function in various pathologies, little is known about the (patho)physiological functions of extrahepatic prothrombin expression. By generating bone marrow chimeric animals in which prothrombin is selectively ablated in the bone marrow compartment, we recently observed a critical function of bone marrow-derived prothrombin in septicemia. Ablation of prothrombin expression specifically in bone marrow-derived cells led to a higher survival rate in septicemia despite unaltered serum levels of prothrombin. To identify cell type(s) expressing prothrombin in the bone marrow compartment, we employed magnetic- (MACS) and fluorescence-activated cell sorting (FACS) followed by luminometry based on purified cells obtained from a newly designed transgenic mouse model (termed ‘D-Insight’) in which endogenous prothrombin expression is tagged by luciferase reporters. Isolating different bone marrow-derived cell populations by MACS and FACS followed by luminometry, we identified antigen-experienced CD4- and CD8- positive T-cells to express prothrombin. We now want to decipher the enigmatic functional role of bone marrow-derived prothrombin expression in the modulation of septicemia. To this end, we will make use of tissue-specific prothrombin knock-out mice and combine this with functional studies in vivo and in vitro, omics and pharmacological approaches to disentangle the role of T-cell derived prothrombin in septicemia. Illuminating non-canonical functions of coagulation components beyond their hemostatic functions is central to elucidate their contribution to the pathophysiologies of very common and most devastating disorders. This may also aid novel avenues to identify rationalized targets for combatting septicemia, an up-to-date fatal condition for a significant proportion of affected patients around the globe.