Cellular Basis of PVL in Autopsied Human Brain

早产儿脑室周围白质软化症(PVL)的主要原因是：1)脑 缺血/再灌流导致脑血管不成熟和自我调节受损；和/或2)母胎细菌感染，在胎儿脑部引发炎症/细胞因子反应。在第一个赠款周期中，我们在人类PVL进行的神经病理学研究证明了大量的自由基损伤早髓鞘少突胶质细胞(Pre-Ols)，这种损伤可能是由脑缺血和感染共同作用引起的。这些研究还表明，激活的小胶质细胞和反应性星形胶质细胞在促进或改善这种损伤方面发挥了关键作用。此外，我们还发现PVL与灰质损伤有关。 对认知功能至关重要的部位，因此表明这种损伤导致早产儿长期的神经障碍。本项目的总体假设是，硝化和氧化损伤在PVL及其相关损伤的易损灰质部位的发病机制中起主要作用。在六个特定的目标中，我们将深入研究PVL对脆弱的前OLs和现在的神经元，包括板下神经元的硝化和氧化损伤的细胞特征。我们还将确定少突胶质细胞、星形胶质细胞、 小胶质细胞和神经元发育，这可能会使未成熟的白质处于危险之中。在我们PVL组织库的支持下，我们将收集和分析组织样本，进行单标记和双标记免疫细胞化学、mRNA的原位杂交和蛋白质印迹分析，以选择与自由基生物学和损伤以及炎症反应相关的参数。提出的特定目标、假设和方法建立在PVL第一周期的发现基础上，但却是新颖的，有可能导致对其发病机制的新见解。充分了解人脑PVL的细胞基础对于在直接相关的实验模型中建立基本的潜在机制是至关重要的 最终导致在临床试验中进行测试的治疗干预。

The major causes of periventricular leukomalacia (PVL) in the premature infant are: 1) cerebral ischemia/reperfusion compounded by cerebral vascular immaturity and impaired autoregulation; and/or 2) maternofetal bacterial infection that triggers an inflammatory/cytokine response in the fetal brain. In the first grant cycle, our neuropathologic studies in human PVL demonstrated evidence for extensive free radical injury to premyelinating oligodendrocytes (pre-OLs) that is presumably triggered by cerebral ischemia and infection acting in concert. These studies also implicated critical roles for activated microglia and reactive astrocytes in contributing to or ameliorating this injury. Moreover, we found that PVL is associated with injury to gray matter sites critical to cognitive function, thus suggesting that this injury contributes to the long-term neurological handicaps in premature infants. The overall hypothesis of this Project is that nitrative and oxidative injury plays a major role in the pathogenesis of PVL and its associated injury in vulnerable gray matter sites. In six specific aims, we will examine in depth cellular features of nitrative and oxidative injury in PVL to vulnerable pre-OLs and now neurons, including subplate neurons. We also will determine factors in oligodendrocyte, astrocytic, microglial, and neuronal development that potentially place the immature white matter at risk. Under the auspices of our PVL Tissue Bank, we will accrue and analyze tissue samples with single- and double-labeled immunocytochemistry, in situ hybridization for mRNA, and western blot analysis for selected parameters related to free radical biology and injury, as well as the inflammatory response. The proposed specific aims, hypotheses, and approaches build upon the first cycle's findings in PVL, yet are novel and have the potential to lead to new insights into its pathogenesis. A full understanding of the cellular basis of PVL in the human brain is essential for establishing basic underlying mechanisms in directly relevant experimental models, in turn ultimately resulting in therapeutic interventions for testing in clinical trials.