Interaction of Estrogen and Tissue Plasminogen Activator

描述(由申请人提供)： 重组组织型纤溶酶原激活剂(RtPA)对急性治疗有效的证明正在改变缺血性卒中的治疗方法。然而，十多年后，tPA疗法的使用仍然有限。几个因素可能导致这一限制：随着时间的推移，脑缺血导致的不可逆转的细胞损伤；rtPA治疗的高危出血性转化患者的概况；以及rtPA的潜在有害影响。延长rtPA纤溶时间窗超过3小时的联合药物治疗策略正在积极研究中。原则上，通过使用神经保护性药物来延长rtPA治疗的治疗窗口是可能的。众所周知，雌激素可以减轻NMDA激活引起的神经毒性。初步证据表明，17-雌二醇通过抑制基质金属蛋白酶2和9(MMP2，MMP9)的激活而稳定血脑屏障(BBB)，而MMP2和MMP9是与出血转化相关的主要因素。17°-雌二醇可减弱rtPA诱导的原代星形胶质细胞MMP2和MMP9的激活。最重要的是，我们在雌性大鼠大脑中动脉闭塞(MCAO)模型中证明了17-雌二醇延长了rtPA的治疗窗口期。因此，雌激素的保护作用使其成为与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的治疗窗口，极大地拓宽其临床应用。目前的应用将验证17-雌二醇延长rtPA在栓塞性卒中的治疗窗口的假设，并确定其潜在的机制。为实现这些目标，将实现以下具体目标。1)探讨雌激素和rtPA对谷氨酸神经毒性和基质金属蛋白酶(MMPs)激活的影响。2)探讨17-雌二醇是否延长栓塞性卒中雌性大鼠rtPA的治疗窗口期。3)探讨17-雌二醇是否延长了栓塞性卒中雄性大鼠rtPA的治疗窗。该应用的目的是探索雌激素和rtPA联合治疗缺血性卒中的进一步临床试验的可行性。重组组织型纤溶酶原激活剂(RtPA)对急性治疗有效的证明正在改变缺血性卒中的治疗方法。然而，十多年后，rtPA治疗的使用仍然有限，对缺血性中风的总体负担只有轻微的影响。几个因素可能导致这一局限性：随着时间的推移，脑缺血导致的不可逆转的细胞损伤；rtPA治疗的高危出血患者的概况；以及rtPA的潜在副作用。延长rtPA 3小时治疗窗的联合药物治疗策略正在积极研究中。原则上，通过使用神经保护性药物来延长rtPA治疗的治疗窗口是可能的。初步证据表明，雌激素可以预防缺血性中风，并有可能减轻rtPA的副作用。目前的应用将验证17-雌二醇延长rtPA在栓塞性卒中的治疗窗口的假设，并确定其潜在的机制。该应用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.