Translational studies of the Platelet Specific Receptor Trem Like Transcript (TLT

描述（由申请人提供）：血栓形成仍然是西方世界最大的死亡和发病原因之一。本研究旨在识别和理解与血小板功能异常相关的关键成分，并随后开发治疗方法以降低与血小板功能异常相关的死亡率。炎症与血栓形成有着密切的关系。例如，炎症性疾病，如心血管疾病和败血症，引起异常血小板活化，导致血栓形成和/或死亡。控制炎症和止血之间联系的机制定义不清，因此这种联系在我们的知识中仍然是一个空白。众所周知，血小板维持炎症部位的血管完整性，因此炎症性疾病，如心血管疾病和败血症，会引起异常的血小板激活，往往导致死亡。p-选择素启动血小板与白细胞和/或内皮细胞之间的初级接触，因此，一些临床试验旨在通过p-选择素控制炎症，但成功尚不明确。解决这一挑战的早期尝试集中在p-选择素与配体的相互作用上，而不是功能冗余的潜力。这一应用代表了一种将这一有希望的靶点开发成治疗方法的新方法。我们已经克隆了一种血小板表面受体，叫做“髓样细胞触发受体表达”（TREM），就像在小鼠和人类中发现的转录-1或TLT-1一样。TLT-1是丰富的，特异于血小板和巨核细胞，和p-选择素一样，储存在血小板1-颗粒中。可溶性形式的TLT-1 （sTLT-1）显著增强血小板聚集和血小板和内皮细胞中的肌动蛋白聚合；和Treml1缺失小鼠与p-选择素缺失小鼠表现出明显的表型重叠。重叠包括：出血时间延长，中性粒细胞迁移延迟，基础中性粒细胞计数升高和血管炎的Shwartzman模型引起的出血。这些表型相似性表明TLT-1的功能是p-选择素功能的补充。我们假设TLT-1介导的早期细胞骨架重排补充了p-选择素的功能，即血小板与内皮细胞（可能还有白细胞）的初始粘附，从而增强了它们对血液和免疫信号的反应能力。为了验证这一假设，我们制定了以下三个具体目标。AIM 1：明确sTLT-1增加肌动蛋白聚合的机制；AIM 2：明确TLT-1在炎症和血栓形成中的作用。目的3：建立TLT-1/p-选择素（CD62P）双空小鼠（DNTP）模型。我们的实验室已经确定了TLT-1并开发了许多TLT-1试剂，最适合描述TLT-1的功能，并将TLT-1与p-选择素的关联从基础生物学转化为临床意义。

DESCRIPTION (provided by applicant): Thrombosis remains one of largest causes of mortality and morbidity in the western world. This study seeks to identify and understand key components involved with proper platelet function and subsequently to develop therapies to reduce the mortality associated with aberrant platelet function. There is an intimate relationship between inflammation and thrombosis. For example, inflammatory diseases, such as CVD and sepsis, cause aberrant platelet activation, leading to thrombosis and/or death. The mechanisms that control the liaison between inflammation and hemostasis are poorly defined, and thus this liaison remains a gap in our knowledge. It is known that platelets maintain vascular integrity at sites of inflammation, and consequently inflammatory diseases, such as CVD and sepsis, cause aberrant platelet activation often leading to death. P-selectin initiate's primary contact between platelets and leukocytes and/or endothelial cells and consequently, several clinical trials have been targeted at controlling inflammation via p-selectin, but success has been elusive. Early attempts to solve this challenge have focused on p-selectin interactions with ligands, rather than the potential for redundancy in function. This application represents a new approach to developing this promising target into treatment. We have cloned a platelet surface receptor called "triggering receptor expressed in myeloid cells" (TREM) like transcript-1, or TLT-1, that is found in mice and humans. TLT-1 is abundant, specific to platelets and megakaryocytes, and like p-selectin, stored in the platelet 1-granules. The soluble form of TLT-1 (sTLT-1) significantly enhances platelet aggregation and actin polymerization in platelets and endothelial cells; and Treml1 null mice show distinct phenotypic overlap with p- selectin null mice. The overlap includes: prolonged bleeding times, delayed neutrophil migration, higher basal neutrophil counts and hemorrhage in response to the Shwartzman model of vasculitis. These phenotypic similarities suggest that TLT-1 function complements that of p-selectin. We hypothesize that TLT-1 mediation of early cytoskeletal rearrangements complements p-selectin's function of initial adhesion of platelets to endothelial cells, and possibly leukocytes, thereby potentiating their ability to respond to both hematological and immunological cues. To test this hypothesis we have developed the following three specific aims. AIM 1: Define the mechanism by which sTLT-1 increases actin polymerization, AIM 2: Define the role of TLT-1 in inflammation and thrombosis. AIM 3: Develop the TLT-1/p-selectin (CD62P) double null mouse (DNTP) model. Our laboratory, having identified TLT-1and developed many TLT-1 reagents is the best suited to delineate TLT-1 function and to translate TLT-1's association with p-selectin from basic biology into clinical significance.