Interaction of Estrogen and Tissue Plasminogen Activator

描述（由申请人提供）： 重组组织纤溶酶原激活剂 (rtPA) 可用于急性治疗的证据正在改变缺血性中风的治疗方法。然而，十多年过去了，tPA 疗法的使用仍然有限。有几个因素可能导致这种限制：随着时间的推移，脑缺血引起不可逆的细胞损伤；接受 rtPA 治疗的出血性转化高风险患者的概况；以及 rtPA 的潜在有害影响。将 rtPA 纤溶时间窗延长至 3 小时以上的联合药物治疗策略正在积极研究中。原则上，通过使用神经保护药物可以延长 rtPA 治疗的治疗窗。众所周知，雌激素可以减少 NMDA 激活引起的神经毒性。该提案提出的初步证据表明，17β-雌二醇通过抑制基质金属蛋白酶2和9（MMP2、MMP9）激活（与出血转化相关的主要因素）来稳定血脑屏障（BBB），防止脑缺血再灌注损伤。 17β-雌二醇减弱原代星形胶质细胞中 rtPA 诱导的 MMP2 和 MMP9 激活。最重要的是，我们已经证明，在栓塞性大脑中动脉闭塞（MCAO）模型中的雌性大鼠中，17'-雌二醇在预处理后可延长 rtPA 的治疗窗。因此，雌激素的保护特性使其成为与 rtPA 联合治疗的良好候选者。雌激素的神经保护作用可以延缓不可逆的细胞损伤。此外，雌激素可以减轻rtPA的副作用，从而延长rtPA的治疗窗并大大拓宽其临床应用。本申请将测试 17'-雌二醇延长 rtPA 在栓塞性中风中的治疗窗的假设，并确定其潜在机制。为了实现这些目标，将解决以下具体目标。 1) 评估雌激素和 rtPA 对谷氨酸神经毒性和基质金属蛋白酶 (MMP) 激活的相互作用。 2) 确定 17¿-雌二醇是否可以延长栓塞性中风模型中雌性大鼠 rtPA 的治疗窗。 3) 确定 17¿-雌二醇是否可以延长栓塞性中风模型中雄性大鼠 rtPA 的治疗窗。该申请的目的是探索雌激素和 rtPA 联合治疗缺血性中风的进一步临床试验的可行性。重组组织纤溶酶原激活剂 (rtPA) 可用于急性治疗的证明正在改变缺血性中风的治疗方法。然而，十多年过去了，rtPA 疗法的使用仍然有限，并且对缺血性中风的总体负担仅产生了有限的影响。有几个因素可能导致这种限制：随着时间的推移，脑缺血引起不可逆的细胞损伤；接受 rtPA 治疗的高出血风险患者概况；以及 rtPA 的潜在副作用。正在积极研究扩大 rtPA 3 小时治疗窗的联合药物治疗策略。原则上，通过使用神经保护药物可以延长 rtPA 治疗的治疗窗。该提案中提出的初步证据表明，雌激素可以预防缺血性中风，并可能减轻 rtPA 的副作用。本申请将测试 17'-雌二醇延长 rtPA 在栓塞性中风中的治疗窗的假设，并确定其潜在机制。该申请的目的是探索雌激素和 rtPA 联合治疗缺血性中风的进一步临床试验的可行性。

DESCRIPTION (provided by applicant): The demonstration that recombinant tissue plasminogen activator (rtPA) is useful for acute management is changing the approach to ischemic stroke. However, after more than a decade, the use of tPA therapy remains limited. Several factors could contribute to this limitation: irreversible cell damage induced by cerebral ischemia over time; the profile of rtPA treated patients at high risk of hemorrhagic transformation; and the potential detrimental effects of rtPA. Combination pharmacotherapy strategies to expand the rtPA fibrinolysis time window beyond 3 hours are under active investigation. In principle, it may be possible to extend the therapeutic window for rtPA therapy by using a neuroprotective drug. Estrogen is well known to diminish the neurotoxicity caused by NMDA activation. Preliminary evidence is presented in this proposal showing that 17¿-estradiol stabilizes blood brain barriers (BBB) against cerebral ischemia reperfusion injury through inhibition of matrix metalloproteinase 2 and 9 (MMP2, MMP9) activation, the major factors related to hemorrhagic transformation. 17¿-estradiol attenuates rtPA induced MMP2 and MMP9 activation in primary astrocytes. Most importantly, we have demonstrated that 17¿-estradiol extends the therapeutic window of rtPA upon pretreatment in female rats in an embolic middle cerebral artery occlusion (MCAO) model. Thus, the protective properties of estrogen make it a good candidate for combination therapy with rtPA. The neuroprotective effects of estrogen could delay irreversible cell damage. Further, estrogen may attenuate the side effects of rtPA, thereby prolonging the therapeutic window of rtPA and greatly broaden its clinical application. The present application will test the hypothesis that 17¿-estradiol extends therapeutic window of rtPA in embolic stroke, and determine the underlain mechanisms. To achieve these objectives, the following specific aims will be addressed. 1) To assess the interaction of estrogen and rtPA on glutamate neurotoxicity and matrix metalloproteinases (MMPs) activation. 2) To determine if 17¿-estradiol extend the therapeutic window of rtPA in female rats in an embolic stroke model. 3) To determine if 17¿-estradiol extend the therapeutic window of rtPA in male rats in an embolic stroke model. The application's objectives are to explore the feasibility for further clinical trials of combination therapy of estrogen and rtPA for ischemic stroke.The demonstration that recombinant tissue plasminogen activator (rtPA) is useful for acute management is changing the approach to ischemic stroke. However, after more than a decade, the use of rtPA therapy remains limited and has had only a modest impact in the overall burden of ischemic stroke. Several factors could contribute to this limitation: irreversible cell damage induced by cerebral ischemia over time; the profile of rtPA treated patients at high risk of hemorrhage; and the potential side effects of rtPA. Combination pharmacotherapy strategies to expand the 3 hour therapeutic window rtPA are under active investigation. In principle, it may be possible to extend the therapeutic window for rtPA therapy by using a neuroprotective drug. Preliminary evidence is presented in this proposal showing that estrogen can protect against ischemic stroke, and potentially attenuate side effect of rtPA. The present application will test the hypothesis that 17¿-estradiol extends therapeutic window of rtPA in embolic stroke, and determine the underlain mechanisms. The application's objectives are to explore the feasibility for further clinical trials of combination therapy of estrogen and rtPA for ischemic stroke.