Platelet Production and Modification of Inflammmatory HA Fragments in Colitis

说明)： (项目3，De la Motte)结肠炎中炎性HA片段的血小板产生和修饰- 糖链-rlch细胞外基质(Ecm)是目前研究中常被忽视的一个因素。 发炎。然而，越来越多的证据表明ECM，特别是透明质酸(HA)是一种 免疫细胞微环境中的动态参与者。HA片段正在获得关注，因为 “内源性危险信号”调节先天免疫反应，并经常促进炎症。 然而，在细胞环境中产生足够数量的碎片以调节 答复尚未定义。我们有证据表明，血小板在细胞外产生HA碎片 环境通过两种机制：1)从激活的小血管表面裂解HA 内皮通过其表面透明质酸酶，透明质酸2；和2)内源性，内部透明质酸排出 在激活过程中。我们假设，通过产生信号大小的HA片段，血小板会加剧 并使炎症持续存在。首先，我们建议确定导致血小板死亡的一系列细胞事件 切割内皮细胞表面的HA片段，对释放的HA进行生化表征，并 测试这一级联反应的中断是否会影响结肠炎小鼠模型的炎症。第二，我们 建议确定血小板中HA的来源和释放它的细胞机制，以 对这种内源性HA进行生化表征，并测试血小板HA缺失是否会影响 活体结肠炎模型中的炎症。第三，我们建议测试由 血小板透明质酸2夹持，或血小板在脱颗粒过程中释放的HA片段，或商业纯化 与血小板大小相似的HA产生的碎片将激活单核细胞和血小板本身。最终 这些研究将确定两种新的糖链介导的机制，通过这些机制，血小板有助于 炎症，这是一个与包括IBD在内的许多疾病有关的极具临床意义的领域。这些数据很可能 显示了细胞外基质在被血小板修饰后所通过的有组织的途径 炎症反应。 相关性(请参阅说明)： 血小板，除了在凝血中起中心作用外，还被认为是炎症的介质。我们 认为血小板通过产生促炎症的HA片段，促进炎症循环 在微血管内加重和延续慢性炎症性疾病，例如 炎症性肠病。

instmctions): (Project 3, de la Motte) Platelet Production and Modification of Inflammmatory HA Fragments in Colitis - The glycan-rlch extracellular matrix (ECM) is a commonly overlooked element in the investigation of inflammation. However, an increasing body of evidence implicates ECM, especially hyaluronan (HA) as a dynamic participant in the immune cell microenvironment. HA fragments are gaining attention as 'endogenous danger signals' that regulate Innate Immune responses and frequently promote inflammation. Yet specific mechanisms that create fragments in the cellular environment in sufficient quantity to mediate responses have not been defined. We have evidence that platelets produce HA fragments in extracellular environments by two mechanisms: 1) cleavage of HA from the surface of activated, small vessel endothelium by means of their surface hyaluronidase, HYAL2; and 2) extrusion of endogenous, internal HA during activation. We hypothesize that platelets, by generating signaling sized HA fragments, exacerbate and perpetuate inflammation. First, we propose to identify the cascade of cellular events that lead platelets to cleave HA fragments from endothelial cell surfaces, to biochemically characterize the HA liberated, and to test whether interruption of this cascade will impact inflammation in a mouse model of colitis. Second, we propose to determine the source of HA in platelets and the cellular mechanism that releases it, to biochemically characterize this endogenous HA, and to test whether deletion of platelet HA affects inflammation in the in vivo colitis model. Third, we propose to test whether HA fragments produced by platelet HYAL2 clipping, or HA fragments released by platelets during degranulation, or commercial purified HA of similar sizes to platelet created fragments will activate monocytes and platelets themselves. Ultimately these studies will define two new, glycan-mediated mechanisms whereby platelets contribute to inflammation, an area of great clinical interest pertaining to many diseases Including IBD. The data will likely show an organized pathway through which the ECM, after modification by platelets, contributes to inflammatory responses. RELEVANCE (See instructions): Platelets, in addition playing a central role in coagulation, are recognized as mediators of inflammation. We propose that platelets, by producing pro-inflammatory HA fragments, contribute to a cycle of inflammation within the microvasculature that exacerbates and perpetuates chronic inflammatory diseases, such as inflammatory bowel disease.