Layilin as a modulator of platelet activation and thromboinflammation

摘要 炎症性肠病(IBD)的特点是结肠和结肠内不适当的免疫细胞浸润。 这种疾病的发病率每年都在增加。在目前无法治愈的情况下，患者只能通过 手术和免疫抑制剂。细胞外基质成分透明质酸(HA)被合成成 炎症过程中的索状结构，作为招募的白细胞的附着点。血小板结合到 这些线缆会降解HA，这种代谢HA的能力在IBD期间就会丧失。这些HA片段 在释放到循环中时具有促炎作用。然而，目前尚不清楚血小板是如何识别HA的。 我们的长期目标是通过靶向确定IBD患者非侵入性治疗的潜在药物靶点 血小板上的HA受体。我们之前发现，与预期相反，占主导地位的 血小板上的HA受体不是CD44，而是一种未被研究的受体Laylin。这项建议的目的是 利用人IBD患者和小鼠血小板来确定透明质酸受体Laylin在IBD中的作用 血小板。这种受体在IBD患者中表达下调，与公认的血小板功能障碍有关 在病人身上。初步结果显示，抑制这种受体会导致血小板聚集、扩散、 和HA的降解。这一建议的中心假设是，血小板驱动的HA的调节失调 新陈代谢促进表达CD44的细胞(如白细胞)在肠道中的募集和激活 微血管系统。该项目的基本原理是雷公藤红素可能成为治疗血小板的新靶点。 慢性炎症性疾病中的调节失调。它可能是血小板活化的负性调节因子 根据我们的初步结果。核心假设将通过检验两个具体目标来检验：1) 确定Laylin如何介导细胞信号驱动血小板活化，2)通过以下方式确定其机制 哪种雷公藤对小鼠结肠炎模型的炎症有影响。这种方法是创新的，因为它针对 未被广泛研究的血小板过度活跃的受体，这是一种在疾病进展中未被广泛研究的细胞类型 IBD的症状。在最终目标中，我们还将利用血小板特异性LAYN KO(PF4-Cre LAYNfl/fl)和WT小鼠来 制作一种新的溃疡性结肠炎小鼠模型。这项拟议的研究意义重大，因为我们预计 本研究旨在开发一种无创治疗血栓性炎症性疾病的方法。

Abstract Inflammatory Bowel Disease (IBD) is characterized by inappropriate immune cell infiltration within the colon and incidence of this disease grows annually. With currently no cure, patients can only mitigate symptoms through surgery and immunosuppressants. An extracellular matrix component, hyaluronan (HA), is synthesized into cable-like structures during inflammation that act as attachment sites for recruited leukocytes. Platelets bind to these cables and degrade the HA and this capability to metabolize HA is lost during IBD. These HA fragments have pro-inflammatory effects when released into circulation. How platelets recognize HA, however, is unknown. Our long-term goal is to determine a potential drug target for non-invasive treatment in IBD patients by targeting HA receptors on platelets. We have previously found that, contrary to what would be expected, the predominant HA receptor on platelets is not CD44, but the understudied receptor, layilin. The objective of this proposal is to utilize both human IBD patients and murine platelets to determine the role of the hyaluronan receptor, layilin, in platelets. This receptor is downregulated in IBD patients, correlating to the well-documented platelet dysfunction in patients. Preliminary results show that inhibiting this receptor results in loss of platelet aggregation, spreading, and HA degradation. The central hypothesis of this proposal is that dysregulation of platelet-driven HA metabolism enhances recruitment and activation of CD44-expressing cells, such as leukocytes, into the intestinal microvasculature. The rationale for this project is that layilin could be a novel target for treatment of platelet dysregulation in chronic inflammatory diseases. It may be acting as a negative regulator for platelet activation based on our preliminary results. The central hypothesis will be tested by examining two specific aims: 1) to determine how layilin mediates cell signaling driving platelet activation and 2) to determine the mechanism by which layilin influences inflammation in a murine model of colitis. This approach is innovative because it targets the understudied receptor in hyperactive platelets, a cell type not extensively investigated in disease progression of IBD. In the final aim, we will also be utilizing platelet specific LAYN KO (PF4-Cre LAYNfl/fl) and WT mice to produce a novel murine model for ulcerative colitis. The proposed research is significant because we anticipate this research to develop a non-invasive treatment for thromboinflammatory diseases.