Iron, minocycline and brain injury after intracerebral hemorrhage

 描述（由申请人提供）：自发性脑内出血（ICH）是一种常见且往往致命的卒中亚型。如果患者在发作后存活，脑实质内产生的血肿会引发一系列事件，导致二次损伤和严重的神经功能缺损。虽然人类的血肿在几个月内逐渐消退，但功能恢复是分级的，通常是不完全的。ICH患者的神经功能缺损是永久性和致残性的。 铁超载和氧化应激有助于脑出血后的脑损伤。铁螯合剂和自由基清除剂均能减轻ICH诱导的动物脑损伤。米诺环素，第二代四环素为基础的分子，是一种有效的小胶质细胞激活抑制剂。它是一种高度亲脂性的化合物，很容易穿透脑血屏障。米诺环素可以螯合铁，最近的一项研究表明，米诺环素通过螯合铁减弱皮质神经元培养中的铁神经毒性。在我们的初步研究中，我们还证明：1）脑出血大鼠模型中出现脑铁超载，米诺环素降低脑出血后脑内非血红素铁水平; 2）米诺环素而不是巨噬细胞/小胶质细胞抑制因子与铁共同注射可消除幼年大鼠铁诱导的脑水肿; 3）米诺环素可减轻幼年大鼠脑出血后的脑水肿、脑萎缩和神经功能缺损;（4）脑出血后血清总铁水平升高，全身应用米诺环素可降低血清总铁水平。然而，我们在米诺环素和ICH方面的知识空白需要填补。例如，尚不清楚米诺环素是否以剂量依赖性方式减轻ICH诱导的铁过载和脑损伤，米诺环素是否可以减少老年ICH动物的脑损伤（ICH主要是老年人的疾病），以及米诺环素是否减少ICH后的白色物质损伤。因此，在本申请中，我们提出测试以下具体目的：1）确定米诺环素是否作为联合疗法通过铁螯合和小胶质细胞抑制来减少老年大鼠中ICH诱导的脑损伤; 2）确定米诺环素是否减少老年大鼠脑内出血后的脑铁过载和脑损伤; 3）确定米诺环素是否减少猪ICH诱导的脑铁过载和脑损伤。来自拟定研究的数据对于开发米诺环素-ICH试验非常有用。 我们的项目的目的是确定米诺环素是否能减少老年大鼠和猪的脑铁超载和ICH诱导的脑损伤。我们研究的长期目标是限制患者的出血性脑损伤。

 DESCRIPTION (provided by applicant): Spontaneous intracerebral hemorrhage (ICH) is a common and often fatal stroke subtype. If the patient survives the ictus, the resulting hematoma within brain parenchyma triggers a series of events leading to secondary insults and severe neurological deficits. Although the hematoma in human gradually resolves within several months, restoration of function is graded and usually incomplete. The neurological deficits in ICH patients are permanent and disabling. Iron overload and oxidative stress contribute to brain damage after ICH. Both iron chelators and free radical scavengers can reduce ICH-induced brain injury in animals. Minocycline, a second-generation tetracycline-based molecule, is a potent inhibitor of microglia activation. It is a highly lipophilic compound and penetrates the brain-blood barrier easily. Minocycline can chelate iron and a recent study has shown that minocycline attenuates iron neurotoxicity in cortical neuronal culture by chelating iron. In our preliminary study, we also have demonstrated: 1) Brain iron overload occurs in a rat model of ICH and minocycline reduces brain non-heme iron levels following ICH; 2) Coinjection of minocycline rather than macrophage/microglia inhibitory factor with iron abolishes iron-induced brain edema in young rats; 3) Minocycline reduces brain edema, brain atrophy and neurological deficits after ICH in young rats; 4) Levels of serum total iron are increased after ICH, which is reduced by systemic use of minocycline. However, major gaps in our knowledge regarding minocycline and ICH need to be filled. For example, it is not clear whether minocycline attenuates ICH-induced iron overload and brain injury in a dose dependent manner, whether minocycline can reduce brain injury in aged ICH animals (ICH is primarily a disease of the elderly), and whether minocycline reduces white matter damage after ICH. In this application, therefore, we propose to test the following Specific Aims: 1) To determine whether minocycline acts as a combination therapy reducing ICH-induced brain injury via iron chelation and microglial inhibition in aged rats; 2) To determine whether minocycline reduces brain iron overload and brain injury after intracerebral hemorrhage in aged rats; 3) To determine whether minocycline reduces ICH-induced brain iron overload and brain damage in pigs. Data from the proposed studies are very useful for developing a minocycline-ICH trial. The purpose of our project is to determine whether minocycline reduces brain iron overload and ICH-induced brain damage in aged rats and pigs. The long-term goal of our studies is to limit hemorrhagic brain damage in patients.