Crotalus Snake Venom Preconditioning to Prevent Surgical Brain Injury

描述（由申请人提供）：全球每年有超过2亿例大型选择性手术。随着医疗保健成本的上升，预防措施越来越与医疗实践相关。预适应（PC）是一种先发制人的治疗方法，在重大损伤之前给予轻度有害刺激以诱导内源性保护机制，在许多损伤模型中显示出保护作用。鉴于大多数神经外科手术的选择性，外科脑损伤（SBI）模型是PC的理想平台。在SBI中，神经外科操作（切口、回缩和电凝）对健康组织造成的附带损伤导致脑水肿和出血。我们建议在PC中加入小剂量的Crotalus蛇毒，以其炎症和出血作用而闻名，以增加对SBI的耐受性。Crotalus毒液含有两种SBI PC感兴趣的蛋白质：磷脂酶2 (PLA2)，一种炎症级联中COX-2上游的酶，以及蛇毒金属蛋白酶（sMMP），一种具有出血作用的酶。已经研究了响尾蛇毒液对凝血功能障碍的诊断能力和治疗效果；并将很快成为SBI治疗的新途径，利用它们的毒性预先上调对炎症和出血性损伤的内源性反应。我们的中心假设是，含有Crotalus毒液（CV-PC）的PC通过诱导对损伤的先天耐受性来缓和SBI的严重程度。我们的初步数据支持了这一前提，表明CV-PC可以减轻大鼠SBI后24小时的脑水肿和出血，并改善神经功能。我们建议系统地研究CV-PC的作用和分子机制。在我们的第一个目标中，我们将评估CV-PC的脑水肿和出血，并确定CV-PC的最佳剂量和毒性。我们期望CV-PC能减少脑水肿、出血和由SBI引起的神经功能缺损。在我们的第二个目标中，我们将检查SBI后炎症介质的表达，评估在给予CV-PC时拮抗PLA2和COX-2的效果，并将PLA2作为SBI的预处理治疗。我们预计CV-PC通过PLA2/COX-2炎症信号通路对SBI产生神经保护作用。在我们的第三个目标中，我们将测量血浆纤维蛋白原和纤维蛋白原降解产物，确定凝血参数，并评估抗sMMP在CV-PC中的作用。我们期望CV- PC通过其纤维蛋白原溶解活性减少SBI出血。我们的长期目标是开发一种有效的、先发制人的SBI治疗方法。我们的建议旨在建立对SBI的更好的机制理解，这将有助于预处理疗法在临床中的应用。如果成功，该建议将改善患者的预后，降低神经外科患者的围手术期护理成本，并可能在其他主要的选择性手术中证明是有益的。

DESCRIPTION (provided by applicant): Over 200 million major elective surgeries are performed worldwide per year. With the rising costs of healthcare, preventative measures grow increasingly relevant to medical practice. Preconditioning (PC), a preemptive therapy in which mildly harmful stimuli are administered to induce endogenous protective mechanisms prior to major injury, has shown to be protective in many injury models. Given the elective nature of most neurosurgical procedures, the surgical brain injury (SBI) model is an ideal platform for PC. In SBI, collateral damage to healthy tissue caused by neurosurgical maneuvers-incision, retraction, and electrocoagulation-result in brain edema and hemorrhage. We propose PC with small doses of Crotalus snake venom, known for their inflammatory and hemorrhagic effects, to increase tolerance to SBI. Crotalus venoms contain two proteins of interest to SBI PC: phospholipase 2 (PLA2), an enzyme upstream to COX-2 in the inflammatory cascade, and snake venom metalloproteinase (sMMP), an enzyme with hemorrhagic effects. Crotalus venoms have been studied for diagnostic capabilities as well as therapeutic effects in coagulative disorders; and will soon be a new avenue of therapy for SBI by utilizing their toxic properties to preemptively upregulate the endogenous response to inflammatory and hemorrhagic injury. Our central hypothesis is that PC with Crotalus venom (CV-PC) will temper the severity of SBI by inducing innate tolerance to injury. This premise is supported by our preliminary data, which demonstrate that CV-PC reduces brain edema and hemorrhage, and improves neurological function 24 hrs after SBI in rats. We propose to systematically examine the effects of and investigate the molecular mechanisms for CV-PC. In our first aim, we will evaluate brain edema and hemorrhage for CV-PC, and determine optimal dosing and toxicity of CV-PC. We expect that CV-PC will reduce the brain edema, hemorrhage, and neurological deficits that result from SBI. In our second aim, we will examine the expression of inflammatory mediators after SBI, evaluate the effects of antagonizing PLA2 and COX-2 while administering CV-PC, and administer PLA2 as a preconditioning treatment in SBI. We expect that CV-PC produces neuroprotective effects for SBI through the PLA2/COX-2 inflammatory signaling pathway. In our third aim, we will measure plasma fibrinogen and fibrinogen degradation products, determine coagulative parameters, and evaluate the effects of antagonizing sMMP in CV-PC. We expect CV- PC reduces hemorrhage in SBI via its fibrinogenolytic activity. Our long-term goal is to develop an effective, preemptive therapy for SBI. Our proposal aims to establish a better mechanistic understanding of SBI that will facilitate the application of preconditioning therapies in the clinic. If successful, this proposal will improve patient outcome and decrease costs of perioperative care for neurosurgical patients and could prove beneficial in other major elective surgeries as well.