PLATELET-ACTIVATING FACTOR IN THROMBOTIC PLATELET-LEUKOCYTE INTERACTIONS

磷脂血小板活化因子（PAF）可能是最强大的促炎和促血栓形成因子。 脂质介质尚未确定。急性炎症系统的所有细胞成分都表达 PAF的单一已知受体。PAF由活化的内皮细胞合成并保留在其表面， 刺激束缚的白细胞。PAF的积累通常是严格控制的，但PAF具有 在血栓形成、脓毒症和再灌注损伤中的作用。 我们对PAF受体配体如何、何时、在何处形成，PAF是如何在体内形成的， 呈现给先天免疫系统的细胞以及PAF刺激的细胞如何与其他细胞相互作用。我们 我不知道是否PAF受体配体在支架置入过程中形成，是否PAF刺激 白细胞为血小板提供血栓素生成的底物，即使当血小板环氧化酶 已被阿司匹林抑制，我们不知道是否由白细胞刺激PAF的产生， 内毒素被包括抗磷脂抗体在内的内源性激动剂模拟。 我们建议确定导致激活限速PAF合成活性的途径， 确定个体是否有不同的能力，使PAF，利用新的信息， 纯化负责PAF合成的酶的技术，用于最终合理的抑制剂设计，以及 鉴定和调节引起微粒形成和PAF释放机制，并确定 这些参数是否与血栓形成相关。我们将定义血栓形成过程中释放的促血栓脂质， 支架置入后，我们将研究产生血栓素Aa的替代途径，并确定这是否 与支架置入后对缓慢复流的敏感性相关，我们将测试替代的内源性 TLR4配体作为白细胞激动剂。我们有四个目标： 目标1.机械定义PMN中粘附依赖性PAF合成。 目标二。白细胞PAF乙酰转移酶合成酶的纯化和分子特征。 目标3：确定通过微粒释放延长PAF作用的因素。 目标4。定义白细胞活化和炎症介质产生的新途径

The phospholipid Platelet-activating factor (PAF) is perhaps the most powerful pro-inflammatory and prothromobtic lipid mediator yet defined. All cellular components of the acute inflammatory system express the single known receptor for PAF. PAF is synthesized by, and retained on the surface of, activated endothelial ceils where it stimulates tethered leukocytes. PAF accumulation normally is tightly controlled, but PAF has a role in thrombosis, sepsis and reperfusion damage. There are deficits in our knowledge of how, when, and where PAF receptor ligands are formed, how PAF is presented to cells of the innate immune system and how PAF stimulated cells interact with other cells. We do not know whether PAF receptor ligands are formed during stent placement, whether PAF stimulated leukocytes provide platelets with substrate for thromboxane production even when platelet cyclooxygenase has been inhibited by aspirin, and we do not know whether PAF production by leukocytes stimulated with endotoxin is mimicked by endogenous agonists that include anti-phospholipid antibodies. We propose to identify the pathways leading to activation of the rate-limiting PAF synthetic activity, determine whether individuals vary in their ability to make PAF, take advantage of new information and techniques to purify the enzyme responsible for PAF synthesis for eventual rational inhibitor design, and identify and modulate mechanisms that cause microparticle formation and PAF release, and to determine whether these parameters correlate with thrombosis. We will define the pro-thrombotic lipids released during stent placement, we will investigate alternate routes to generate thromboxane Aa, and determine whether this correlates with susceptibility to slow reflow after stent placement, and we will test alternate, endogenous ligands of TLR4 as leukocyte agonists. We have four aims: Aim 1. Mechanistically define adhesion-dependent PAF synthesis in PMN. Aim 2. Purify and molecularly characterize the leukocyte PAF acetyltransferase synthetic enzyme. Aim 3. Identify factors that extend the effect of PAF through microparticle release. Aim 4. Define novel routes to leukocyte activation and inflammatory mediator production