Preclinical stroke trial with the PARP inhibitor veliparib

甲状旁腺激素是一种细胞死亡信号通路，DNA过度氧化损伤导致聚腺苷二磷酸核糖聚合酶(PARP)过度激活，进而刺激形成大的聚腺苷二磷酸核糖聚合物，从而诱导线粒体膜外释放凋亡诱导因子(AIF)。在胞浆中，AIF与巨噬细胞移动抑制因子(MIF)形成一个复合体，该复合体移位到细胞核中，在那里MIF降解DNA并导致细胞死亡。对文献的回顾显示，有23篇文献支持在大脑中动脉一过性和永久性闭塞(MCAO)的年轻雄性小鼠和大鼠中，基于使用来自13个不同实验室的9种不同的PARP抑制剂(19项研究)或PARP1缺失小鼠(6项研究)。多项研究表明，MCAO后的治疗窗口为4-6小时。在年轻的雌性大鼠中，来自两个实验室的两项研究支持基于使用两种不同的PARP抑制剂的帕金森症的作用，而来自一个实验室的两项研究不支持年轻的雌性PARP1缺失小鼠的作用。除了肝素介导的神经细胞死亡外，大量文献表明，PARP抑制剂可以通过干扰小胶质细胞中NFkB的转录，抑制基质金属蛋白酶-9的释放，限制血脑屏障的损伤和出血性转化来减轻神经炎症。总体而言，大多数文献强烈支持PARP抑制剂具有神经保护作用的科学前提，即使它是在MCAO后再灌流时给予的。然而，还没有关于大脑中动脉阻塞的研究在老年动物身上测试PARP抑制剂，已知这些动物具有衰老的免疫系统，性激素的保护作用减弱。因为老年动物被认为与人类中风人群在翻译上更相关，所以在进入中风临床试验之前，应该在老年动物身上测试PARP抑制剂，无论性别。我们建议在老年雄性和雌性小鼠MCAO后再灌注时测试PARP抑制剂veliparib，基于其良好的脑穿透性和在人类肿瘤学试验中已确定的安全性。我们计划的主要结果是在中风后一个月内表现出持续缺陷的伸手抓住灵活性任务的一个月表现。次要结果包括其他四项感觉运动任务的短期缺陷，一个月后的恐惧条件反射认知，一个月后的脑萎缩，以及病变体积、CBF的急性MRI测定，以及DTI与组织pH图的不匹配。该团队由一位拥有30年MCAO临床前研究经验的PI领导，一位在兴奋毒性和中风模型中阐明副死亡信号的神经科学家，一位在中风后小鼠神经行为测试方面拥有专业知识的中风临床医生，一位在开发用于中风和其他疾病的新脑成像方式方面拥有25年经验的磁共振科学家，以及一位在啮齿动物多模式磁共振成像方面具有专长的MR科学家。该团队在实验性中风方面有着长期的合作历史，并高度致力于SPAN任务的科学严谨性，作为六种候选药物的试验场，用于缺血性中风的再灌注治疗。

Parthanatos is a cell death signaling pathway in which excessive oxidative damage to DNA leads to over- activation of poly(ADP-ribose) polymerase (PARP), which then stimulates the formation of large poly(ADP- ribose) polymers that induce the release of apoptosis-inducing factor (AIF) from the outer mitochondrial membrane. In the cytosol, AIF forms a complex with macrophage migration inhibitory factor (MIF) that translocates into the nucleus where the MIF degrades DNA and produces cell death. A review of the literature reveals 23 publications that support a role for parthanatos in young male mice and rats subjected to transient and permanent middle cerebral artery occlusion (MCAO) based on the use of 9 different PARP inhibitors (19 studies) or PARP1 null mice (6 studies) from 13 different labs. Several studies indicate a therapeutic window of 4-6 h after MCAO. In young female rats, 2 studies from 2 labs support a role for parthanatos based on the use of 2 different PARP inhibitors, whereas 2 studies from one lab do not support a role in young female PARP1 null mice. In addition to parthanatos-mediated neuronal cell death, a body of literature indicates that PARP inhibitors can reduce neuroinflammation by interfering with NFkB transcription in microglia, suppressing MMP- 9 release, and limiting blood-brain barrier damage and hemorrhagic transformation. Overall, most of the literature strongly supports the scientific premise that a PARP inhibitor is neuroprotective, even when it is given at reperfusion after MCAO. However, no studies of MCAO have tested PARP inhibitors in aged animals known to have a senescent immunologic system and diminished protection by sex hormones. Because aged animals are thought to be more translationally relevant for the human stroke population, a PARP inhibitor should be tested in aged animals of both sexes before moving into clinical stroke trials. We propose testing the PARP inhibitor veliparib at reperfusion after MCAO in aged male and female mice based on its good brain penetration and its established safety in human oncology trials. Our planned primary outcome is one-month performance on a reaching-to-grasp dexterity task known to display sustained deficits for over a month after stroke. Secondary outcomes include short-term deficits in four other sensorimotor tasks, fear conditioning cognition at one month, brain atrophy at one month, and acute MRI determinations of lesion volume, CBF, and mismatch of DTI with tissue pH maps. The team is led by a PI with 30 years of experience in performing preclinical studies of MCAO, neuroscientists who elucidated parthanatos signaling in models of excitotoxicity and stroke, a stroke clinician with expertise in neurobehavior testing in mice after stroke, an MR scientist with 25 years of experience in developing new modalities of brain imaging for use in stroke and other disorders, and a MR scientist with expertise in multimodal MR imaging in rodents. The team has a long history of collaborating together on experimental stroke and is highly dedicated to the scientific rigor of the SPAN mission by serving as a test site for six candidate drugs for adjunct use with reperfusion therapies in ischemic stroke.