Molecular Imaging of FXIII in a Mouse model Coronary Microvascular Disease

描述（由申请人提供）：冠状动脉微血管疾病（MVD）在多达300万无阻塞性冠状动脉疾病（CAD）的缺血性症状的美国女性中普遍存在。尽管近年来在常规诊断和心血管造影方面取得了进展，但冠状动脉MVD的临床诊断和治疗仍然令人失望。冠状动脉MVD的发病机制尚不清楚，容易导致漏诊或误诊。与传统的心外膜CAD不同，由各种活性氧（ROS）引起的弥漫性内皮功能障碍是MVD的病理标志，进而引发局灶性促血栓形成和抗纤溶。活化的FXIII （FXIIIa）通过介导纤维蛋白-纤维蛋白和纤维蛋白-¿2-抗纤溶蛋白交联在血栓形成的稳定中起关键作用。近年来，纤维蛋白已被检测为急性心肌梗死的主要复合物，并随着缺血时间的延长而增加。在此，我们认为微血栓和FXIII可能在mvd诱导的缺血过程中起关键作用。我们假设FXIII是冠状动脉MVD的特异性生物标志物，其活性可以通过FXIII靶向放射性标记探针在体内和体外评估。在机制水平上，我们也假设微血管可能比大血管对氧化应激诱导的内皮功能障碍更敏感。FXIII活性增加的评估可以预测长期功能结果，如壁运动减少和心功能受损。我们将结合体外和体内方法来检验这些假设，包括；1)从微观和宏观血管衍生的原发性内皮细胞的细胞和分子研究，2)pdt诱导小鼠MVD的新模型的应用，3)应用无创分子成像方法监测MVD设置中FXIIIa的动态激活，以及4)应用最先进的微ct方法评估心脏功能和壁壁运动作为MVD评估的长期终点。因此，本提案有望建立具有临床意义的冠状动脉MVD动物模型，并验证用于冠状动脉MVD检测和风险分层的分子成像探针。从这些研究中产生的信息可能会大大改变我们目前评估和管理冠状动脉MVD的做法。公共卫生意义：心血管疾病是导致死亡的主要原因。内皮功能障碍常引发血栓级联反应，抑制溶栓促进血液凝固，引起心脏多发缺血性病变；因此，对其研究对临床医生极为重要。该项目的结果将为无创监测冠状动脉血栓提供直接证据。因此，凝块内的FXIIIa可作为诊断性生物标志物，判断生物老化，指导治疗，评价纤溶疗效，预测病理预后。

DESCRIPTION (provided by applicant): Coronary microvascular disease (MVD) is prevalent in as many as 3 million American women with ischemic symptoms without obstructive coronary artery disease (CAD). Despite advances in recent conventional diagnoses and cardiovascular angiography, the clinical diagnosing and treating of coronary MVD remains disappointing. The mechanism of coronary MVD is still not well understood, which lead to missed or misdiagnosis. Different from traditional epicardial CAD, diffuse endothelial dysfunction resulting from various reactive oxygen species (ROS) is a pathological hallmark of MVD, which in turn triggers focal pro-thrombosis and anti-fibrinolysis. Activated FXIII (FXIIIa) plays a key role in the stabilizatio of thrombosis by mediating fibrin-fibrin and fibrin- ¿2-antiplasmin cross- links. Recently, fibrin has been detected as a major composite in acute myocardial infarction and increases with ischemic time. Here, we believe that MVD-induced ischemia results from microthrombi and FXIII may play a key role during this process. We hypothesize that FXIII is a specific biomarker for coronary MVD and its activity can be evaluated ex vivo and in vivo by a FXIII targeted radiolabeled probe. At a mechanistic level, we also hypothesize that the microvasculature might be more sensitive to oxidative stress -induced endothelial dysfunction than macro-vasculature. Evaluation of increased FXIII activity may predict long-term functional outcomes, such as decreased wall motion and impaired cardiac function. We will test these hypotheses with a combination of ex vivo and in vivo methods, including; 1) cellular and molecular studies in primary ECs derived from micro- and macro-vasculature, 2) application of a novel model of PDT-induce MVD in mice, 3) application of a non-invasive molecular imaging method to monitor the dynamic activation of FXIIIa in the setting of MVD, and 4) application of a state-of-the-art microCT method for the assessment of cardiac function and wall motion as long-term end-points for the evaluation of MVD. As such, the proposal is expected to establish a clinically relevant animal model of coronary MVD and validate a molecular imaging probe for the detection and risk stratification of coronary MVD. The information generated from these studies may substantially alter our current practice for the evaluation and management of coronary MVD. PUBLIC HEALTH SIGNIFICANCE: Cardiovascular disease is the leading cause of death. Endothelial dysfunction often triggers thrombotic cascade and inhibits thrombolysis to facilitate blood clotting, causing multiple ischemic lesions in the heart; hence, its study is extremely important to clinicians. The results of this project will provide direct evidence to monitor in viv coronary clots non-invasively. Thus, the FXIIIa within clots will serve as a diagnostic biomarker to determine biological aging to guide treatment, to evaluate the efficacy of fibrinolysis, and to predict the prognosis of pathology.