Mechanisms of G-CSF-Induced Neuroprotection

描述（由申请人提供）：尚未开发出有效的治疗策略来预防或减少新生儿缺氧/缺血（HI）脑损伤。粒细胞集落刺激因子（G-CSF）是生长因子家族的成员，主要刺激造血系统中的嗜酸性祖细胞增殖和分化。它已广泛用于临床实践中治疗与细胞毒性治疗相关的中性粒细胞减少症。最近的研究表明，在成年动物模型中全身给予G-CSF对创伤性脑损伤、局灶性短暂性脑缺血和脑出血具有显著的神经保护作用，但其机制尚未完全阐明。G-CSF在新生儿缺氧缺血后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的新调查员，我一直关注这个重要的问题，因为它与国家和地方的健康相关。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）。我在基础和临床科学学科之间架起了桥梁，为这个项目组建了一支优秀的研究团队。我们的初步研究揭示了在对新生儿HI的已建立的大鼠模型全身给予G-CSF后脑萎缩的显著减少，并提供了对作用机制的深入了解。它们支持我们的中心假设，即全身性G-CSF治疗保护脑免受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，该项目旨在确定细胞死亡机制的抑制，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相关（具体目标1）。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变化来测量脑损伤。为了加强该项目的临床相关性，将通过一系列神经学测试评估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。然后，通过测量G-CSF对HI诱导的信号通路激活，特别是线粒体凋亡通路的作用，将更深入地研究G-CSF的潜在机制（具体目标2）。将使用生物化学和分子方法研究凋亡变化。通过这些具体的目标实现我们的项目目标，将为NICU新生儿全身性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：尚未开发出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/缺血诱导的脑损伤的保护与神经功能和潜在机制联系起来。本研究结果为临床评价全身应用G-CSF防治新生儿缺氧缺血性脑损伤奠定了基础。

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.