Crotalus Snake Venom Preconditioning to Prevent Surgical Brain Injury

描述(由申请者提供)：全球每年进行超过2亿次的大型择期手术。随着医疗保健成本的上升，预防措施与医疗实践越来越相关。预适应(PC)是一种在严重损伤前给予轻微有害刺激以诱导内源性保护机制的先发制人治疗方法，已被证明在许多损伤模型中具有保护作用。考虑到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，神经外科操作对健康组织造成的附带损害--切开、回缩和电凝--导致脑水肿和出血。我们建议PC联合小剂量的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蛇毒含有两种与SBI PC相关的蛋白质：磷脂酶2(PLA2)，一种炎症级联反应中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Crotalus蛇毒在凝血障碍中的诊断能力和治疗效果；不久将通过利用其毒性特性先发制人地上调内源性炎症和出血性损伤的反应，从而成为SBI的一种新的治疗途径。我们的中心假设是，含有Crotalus毒液的PC(CV-PC)将通过诱导对损伤的先天耐受性来缓和SBI的严重性。这一前提得到了我们的初步数据的支持，这些数据表明，CV-PC减少了大鼠SBI后24小时的脑水肿和出血，并改善了神经功能。我们建议系统地研究CV-PC的作用并探讨其分子机制。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。我们预计，CV-PC将减少由SBI引起的脑水肿、出血和神经功能障碍。在我们的第二个目标中，我们将检测SBI后炎症介质的表达，评估在应用CV-PC的同时拮抗PLA2和COX-2的效果，并将PLA2作为SBI的预适应治疗。我们期望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，我们将测定血浆纤维蛋白原和纤维蛋白原降解产物，测定凝血参数，并评估抗血管内皮细胞基质金属蛋白酶的效果。我们期望CV-PC通过其纤维蛋白原溶解活性减少SBI的出血。我们的长期目标是开发一种有效的、先发制人的治疗方法。我们的建议旨在建立对SBI的更好的机械性理解，这将促进预适应疗法在临床上的应用。如果成功，这项建议将改善患者的预后，降低神经外科患者围手术期护理的成本，并可能被证明对其他主要的择期手术也是有益的。

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.