Mechanisms of G-CSF-Induced Neuroprotection

描述（由申请人提供）：目前还没有有效的治疗策略来预防或减少新生儿缺氧/缺血性（HI）脑损伤。粒细胞集落刺激因子（G-CSF）是生长因子家族的一员，在造血系统中主要刺激中性粒细胞祖细胞的增殖和分化。它已被广泛应用于临床治疗中性粒细胞减少症与细胞毒性治疗。最近的研究表明，在成年动物模型中全身给药G-CSF在创伤性脑损伤、局灶性短暂性脑缺血和脑出血中具有显著的神经保护作用，但其机制尚未完全阐明。新生儿缺氧缺血后G-CSF是否具有神经保护作用尚不清楚。作为一名医学科学家和NIH的新研究员，我一直关注这个重要的问题，因为它与全国和地方的健康相关。洛马琳达大学医学中心拥有美国西部最大的新生儿重症监护病房（NICU）。我在基础科学和临床科学之间架起了桥梁，组建了一支优秀的研究团队。我们的初步研究显示，在已建立的新生儿HI大鼠模型中全身给予G- CSF后，脑萎缩显著减少，并提供了对其作用机制的见解。它们支持我们的中心假设，即系统性G-CSF治疗可以保护大脑免受hi诱导的细胞凋亡。为了验证我们的主要假设，本项目旨在阐明g - csf介导的神经保护对神经行为结果的影响，从而确定其治疗潜力。同样重要的是，该项目旨在确定抑制细胞死亡机制，特别是介导G-CSF保护作用的线粒体凋亡途径。G-CSF对神经元死亡和脑萎缩的神经保护作用将与神经行为结果有关（Specific Aim 1）。脑损伤将通过脑组织损失、水肿形成、血脑屏障破坏、脑梗死和细胞形态学改变来衡量。为了加强该项目的临床相关性，G-CSF治疗对感觉运动功能、记忆和学习能力的长期影响和机制将通过一系列神经学测试进行评估。然后G-CSF的潜在机制将通过测量其对hi诱导的信号通路特别是线粒体凋亡通路的激活的影响进行更深入的研究（Specific Aim 2）。凋亡的变化将采用生化和分子方法进行研究。通过这些具体目标实现我们的项目目标，将为NICU新生儿系统性G-CSF预防和治疗HI脑损伤的临床评价奠定基础。公共卫生相关性：尚未制定有效的治疗策略来预防或减少新生儿缺氧/缺血性脑损伤。我们的项目目标是将G-CSF对新生儿缺氧/缺血引起的脑损伤的保护与神经功能和潜在机制联系起来。本研究的完成将为新生儿全身给药G-CSF预防和治疗缺氧/缺血脑损伤的临床评价奠定基础。

DESCRIPTION (provided by applicant): No effective treatment strategies have yet been developed to prevent or reduce neonatal hypoxic/ischemic (HI) brain damage. Granulocyte-colony stimulating factor (G-CSF), a member of growth factor family, mainly stimulates the proliferation and differentiation of neutrophilic progenitor cells in the hematopoietic system. It has been widely used in clinical practice for the treatment of neutropenia associated with cytotoxic therapy. Recent studies have shown that systemic administration of G-CSF in adult animal models has mediated noteworthy neuroprotective effects in traumatic brain injury, focal transient cerebral ischemia, and intracerebral hemorrhage but its mechanism(s) are not fully elucidated. Whether G-CSF has neuroprotective effects following neonatal hypoxia-ischemia is not known. As a medical scientist and new investigator to the NIH, I have focused on this important question because of its health relevance, nationally and locally. Loma Linda University Medical Center has the largest Neonatal Intensive Care Unit (NICU) in the Western United States. I have bridged basic and clinical science disciplines to assemble an outstanding research team for this project. Our preliminary studies reveal a significant reduction in brain atrophy following systemic administration of G- CSF to an established rat model of neonatal HI and offer insight into mechanism of action. They support our central hypothesis that systemic G-CSF treatment protects the brain against HI-induced apoptosis. To test our main hypothesis, this project is designated to elucidate the impact of G-CSF-mediated neuroprotection on neurobehavioral outcomes, and thereby define its therapeutic potential. Equally important, this project is designed to determine the suppression of cell death mechanisms especially the mitochondrial apoptotic pathways that mediates the protective effects of G-CSF. The neuroprotective effects of G-CSF on neuronal death and brain atrophy will be related to neurobehavioral outcomes (Specific Aim 1). Brain damage will be measured by brain tissue loss, edema formation, blood-brain barrier disruption, brain infarction, and cellular morphological changes. To strengthen the clinical relevance of this project, the long-term effect and mechanisms of G-CSF treatment on sensorimotor functions, memory and learning abilities will be evaluated by a battery of neurological tests. Then G-CSF's underlying mechanism will be investigated in greater depth by measuring its effect on HI-induced activation of signaling pathways especially mitochondrial apoptotic pathways (Specific Aim 2). The apoptotic changes will be studied using biochemical and molecular approaches. Achieving our project goal through these specific aims will lay the foundation for clinical evaluation of systemic G-CSF in NICU neonates for prevention and treatment of brain damage from HI. PUBLIC HEALTH RELEVANCE: No effective treatment strategies have yet been developed to prevent or reduce neonatal hypoxic/ischemic brain damage. Our project goal is to relate G-CSF's protection of neonates from hypoxia/ischemia-induced brain damage to both neurological function and underlying mechanism. Achieving our goal will lay the foundation for clinical evaluation of systemic administration of G-CSF in human neonates for prevention and treatment of brain damage from hypoxia/ischemia.