Pathology-directed combination therapy for pediatric TBI

描述（由申请人提供）：创伤性脑损伤（TBI）是婴儿和4岁以下儿童发病和死亡的主要原因之一。与年龄较大的儿童和成人的情况一样，损伤严重程度的范围从轻度到重度，以轻中度损伤患者为主要人群。此外，支持性神经重症监护的疗效提高，显著降低了死亡率。总的来说，这些现象导致越来越多的创伤性脑损伤幸存者面临着终生的认知、情感和社交缺陷。尽管闭锁性脑损伤后的病理改变（细胞死亡、轴突损伤、反应性神经胶质瘤和炎症）在成熟和不成熟的大脑中似乎是相似的，但临床和动物研究开始表明，急性和慢性创伤后时期的致病机制在两个年龄之间是相当不同的。第二个问题是，急性神经保护策略是临床试验和临床前研究的支柱，尽管存在多种致病机制，但它仍专注于单一的“灵丹妙药”方法，这为临床试验的失败奠定了基础。因此，本研究旨在填补TBI文献中的这两个空白，方法是采用与年龄相适应、与临床相关的儿科TBI模型，并测试两种旨在限制明显分离的病理通路的策略结合使用后，是否会改善功能结果。17天大的老鼠在神经学上相当于3-4岁的幼童，是首选的动物。在目前的建议中，这两种策略的选择源于初步观察，钙调磷酸酶抑制剂和亲免疫素配体FK506，减轻未成熟大鼠闭合性头部损伤后的创伤性轴索损伤。在单独的实验中，我们观察到抗炎和抗凋亡的三肽Glypromate——内源性来源于胰岛素样生长因子的n端——减少了小胶质细胞的激活、组织钙蛋白酶的激活和随之发生的神经退行性变。通过生化、免疫组织化学、电生理和行为学等综合分析，验证FK506通过抑制钙调磷酸酶介导的神经丝压实和减轻轴突损伤，与抑制小胶质细胞活化、减少细胞因子合成和减轻神经退行性变的Glypromate联合，共同减轻脑损伤未成熟大鼠的急慢性学习记忆缺陷。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality in infants and children under the age of 4. As in the case of older children and adults, the spectrum of injury severity spans the gamut from mild to severe, with mild-moderate injured patients being the predominant population. In addition, increased efficacy of supportive neurointensive care has significantly reduced the mortality. Collectively, these phenomena result in an increasing number of survivors of TBI, who are faced with suffering life-long cognitive, emotional and social deficits. Although the pathologic alterations (cell death, axonal injury, reactive gliosis and inflammation) following closed head injury appears to be similar in both the mature and immature brains, clinical and animal studies are beginning to demonstrate that the pathogenic mechanisms in the acute and chronic post-traumatic periods are fairly dissimilar between the two ages. A second problem is that acute neuroprotective strategies, the mainstay of clinical trials and pre-clinical studies, are focused on a single "magic bullet" approach despite the multitude of pathogenic mechanisms, setting the stage for failure in clinical trials. This proposal therefore seeks to fill these two gaps in the TBI literature by using an age-appropriate, clinically-relevant model of pediatric TBI and testing whether two strategies, each aimed at limiting distinctly separate pathologic pathways, when combined, will improve functional outcome. The 17-day-old rat which is neurologically equivalent to 3-4-year-old toddler is the animal of choice. The choice of the two strategies in the current proposal arises from preliminary observations that the calcineurin inhibitor and immunophilin ligand, FK506, attenuates traumatic axonal injury following closed head injury in immature rats. In separate experiments, it was observed that the anti-inflammatory and anti-apoptotic tripeptide, Glypromate - derived endogenously from the N-terminus of insulin-like growth factor - reduced microglial activation, tissue calpain activation and attendant neurodegeneration. Using a combination of biochemical, immunohistochemical, electrophysiological and behavioral analyses, the hypothesis to be tested is that FK506, by inhibiting calcineurin-mediated neurofilament compaction and decreasing axonal injury, in combination with Glypromate which will inhibit microglial activation, decrease cytokine synthesis and reduce neurodegeneration, will together reduce acute and chronic learning and memory deficits in the brain-injured immature rat. PUBLIC HEALTH RELEVANCE: Brain trauma to the youngest section of the population is a serious health problem. Survivors are faced with life-long disabilities ranging from social and emotional problems to learning and memory deficits. Currently no treatment exists that can alleviate these deficits. This proposal seeks to evaluate approaches that will limit the multiple degenerative changes in order to improve behavioral function following closed head injury in an immature animal.