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

描述(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。这项研究试图识别和了解与正常的血小板功能相关的关键成分，并随后开发治疗方法来降低与异常的血小板功能相关的死亡率。炎症和血栓形成之间有密切的关系。例如，炎症性疾病，如心血管疾病和脓毒症，会导致异常的血小板激活，导致血栓形成和/或死亡。控制炎症和止血之间联系的机制还不清楚，因此这种联系在我们的知识中仍然是一个空白。众所周知，血小板在炎症部位维持血管完整性，因此炎症性疾病，如心血管疾病和败血症，导致异常的血小板激活，通常导致死亡。P-选择素启动了血小板与白细胞和/或内皮细胞之间的主要接触，因此，一些临床试验的目标是通过P-选择素控制炎症，但成功的可能性很小。早期解决这一挑战的尝试主要集中在p-选择素与配体的相互作用上，而不是功能上的冗余。这一应用代表了一种将这一有希望的靶点开发为治疗的新方法。我们已经克隆了一种名为“在髓系细胞中表达的触发受体”(TREM)的血小板表面受体，类似于转录-1，或TLT-1，在小鼠和人类中发现。TLT-1含量丰富，专见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)显著促进了血小板和内皮细胞中的血小板聚集和肌动蛋白聚合；Treml1基因缺失的小鼠与p-选择素缺失的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增加，以及响应Shwartzman血管炎模型的出血。这些表型相似性表明，TLT-1的功能与p-选择素的功能互补。我们假设，TLT-1介导的早期细胞骨架重排补充了P-选择素最初黏附内皮细胞和白细胞的功能，从而增强了它们对血液学和免疫学信号的反应能力。为了验证这一假设，我们制定了以下三个具体目标。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(CD62P)双空鼠(DNTP)模型。我们实验室已经鉴定了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S关系从基础生物学转化为临床意义。 公共卫生相关性：心血管疾病(CVD)和败血症等炎症性疾病是美国和西方世界的主要死亡原因；血小板在这些疾病患者的控制和生存中发挥着重要作用。众所周知，血小板受体P-选择素介导炎症和血栓形成之间的联系，但这一有希望的治疗靶点的成功仍然难以捉摸。TREM样转录本-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所完成的基础科学转化为治疗手段，以帮助数百万患有心血管疾病或脓毒症等炎症性疾病的人。

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.