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死亡和发病的最大原因之一。本研究旨在识别和了解与正常血小板功能相关的关键成分，并随后开发治疗方法以降低与异常血小板功能相关的死亡率。炎症与血栓形成有着密切的关系。例如，炎性疾病，如CVD和败血症，引起异常的血小板活化，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。已知血小板在炎症部位维持血管完整性，并且因此炎性疾病如CVD和败血症引起异常血小板活化，通常导致死亡。P-选择素启动血小板与白细胞和/或内皮细胞之间的主要接触，因此，一些临床试验已经靶向通过P-选择素控制炎症，但成功一直难以捉摸。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，而不是功能冗余的可能性。这一应用代表了将这一有前途的靶点开发成治疗的新方法。我们克隆了一种血小板表面受体，称为“髓样细胞表达的触发受体”（TREM），类似于转录本-1或TLT-1，在小鼠和人类中发现。TLT-1丰富，对血小板和巨核细胞具有特异性，并且像P-选择素一样，储存在血小板1-颗粒中。可溶形式的TLT-1（sTLT-1）显著增强血小板和内皮细胞中的血小板聚集和肌动蛋白聚合; Treml 1缺失小鼠显示出与p-选择素缺失小鼠明显的表型重叠。重叠部分包括：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Shwartzman模型引起的出血。这些表型相似性表明TLT-1功能与P-选择素功能互补。我们推测，TLT-1介导的早期细胞骨架重排补充了P-选择素的功能，血小板的初始粘附内皮细胞，并可能白细胞，从而增强他们的能力，以应对血液和免疫线索。为了验证这一假设，我们制定了以下三个具体目标。目的1：明确sTLT-1促进肌动蛋白聚合的机制，目的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（CD 62 P）双敲除小鼠（DNTP）模型。本实验室已鉴定出TLT-1，并开发了多种TLT-1试剂，最适合于描述TLT-1的功能，并将TLT-1与P-选择素的关系从基础生物学转化为临床意义。 公共卫生相关性：炎症性疾病，如心血管疾病（CVD）和败血症是美国和西方世界的主要死亡原因;血小板在控制和生存这些疾病的人中发挥着重要作用。血小板受体P-选择素介导炎症和血栓形成之间的联系是公认的，但这种有前途的治疗靶点的成功仍然难以捉摸。TREM样转录物-1（TLT-1）也是一种血小板受体，具有与P-选择素相似的特征，可能在P-选择素功能中发挥作用;我们的项目旨在将P-选择素和TLT-1的基础科学转化为治疗手段，以帮助数百万患有炎症性疾病（如CVD或败血症）的人。

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. PUBLIC HEALTH RELEVANCE: Inflammatory diseases such as cardiovascular disease (CVD) and sepsis are major causes of death in the United States and the Western World; platelets play a large role in the control and survivorship of people suffering from these diseases. It is well established that the platelet receptor p-selectin mediates the connection between inflammation and thrombosis but success for this promising therapeutic target remains elusive. TREM like transcript-1 (TLT-1) is also a platelet receptor, with similar characteristics to p-selectin, which may play a role in p-selectin function; our project seeks to translate the basic science completed on p-selectin and TLT-1 into therapeutic means to aid the millions of people suffering from inflammatory diseases such as CVD or sepsis.