Role of Growth Arrest and DNA Damage 45-alpha in Acute Lung Injury Pathogenesis

描述（由申请人提供）：急性肺损伤（ALL）是一种常见的破坏性疾病，在美国每年约有190，000例患者受到影响，死亡率为30 - 50%。ALI的治疗总是需要机械通气，这本身可以增强甚至诱导肺损伤。到目前为止，我们唯一被证实的ALI治疗方法是采用非损伤性通气策略并限制过量静脉输液。由于只有少数具有该疾病危险因素的患者会发展成全面的空域淹没和严重低氧血症综合征，因此更好地了解ALI易感性可能会导致更好和更个性化的治疗。我们的研究集中在动物和人类ALI的表达谱，以探索潜在的基因对ALI发展的贡献，揭示了许多可能与ALI发病机制有关的基因的表达显著升高。生长停滞和DNA损伤诱导基因45 α（GADD 45 a）是一种由细胞损伤激活的组成型表达基因，其导致DNA损伤或细胞周期停滞，是一种响应于ALI而强烈上调的基因。虽然迄今为止它在肺中没有已知的作用，但我们假设GADD 45 a是一个可行的候选基因，可提供对ALI的保护。在本申请中，主要研究者将研究GADD 45 a可能影响急性肺损伤的机制。具体目标#1将采用呼吸机诱导的和脓毒症诱导的ALI的动物模型来测试GADD 45 a敲除菌株是否对肺损伤更敏感。我们将表征GADD 45 a表达在鼠肺组织内的空间位置，并测定鼠肺以确定与对照相比，GADD 45 a敲除是否改变炎性细胞因子如TNF-α、IL-6或IL-1 β的表达。具体目标#2将通过在暴露于循环拉伸或内毒素的细胞培养模型中沉默GADD 45 a并评估对内皮细胞屏障功能的影响来检验我们的假设，即GADD 45 a是ALI中的保护因子。我们还将探讨GADD 45 a在ALI保护中的主要机制作用，区分细胞凋亡调节和p38 MARK失活的假定作用。这些研究将阐明对ALI病理生理学的新见解，这可能为这种毁灭性疾病产生新的治疗靶点。

DESCRIPTION (provided by applicant): Acute Lung Injury (All) is a common and devastating disorder, afflicting an estimated 190,000 patients each year in the United States and inflicting a mortality rate of 30 - 50%. Treatment of ALI invariably necessitates mechanical ventilation, which can itself potentiate or even induce lung injury. To date, our only proven therapies for ALI are to employ a non-injurious ventilation strategy and to limit excess intravenous fluid administration. As only a minority of the patients with risk factors for the disease will develop the full-blown syndrome of airspace flooding and profound hypoxemia, a better understanding of ALI susceptibility might lead to improved and more personalized therapy. Our studies focused on expression profiling of animal and human ALI to explore potential genetic contributions to the development of ALI revealed significantly elevated expression of a number of genes potentially implicated in the pathogenesis of ALI. Growth arrest and DNA damage-inducible gene 45 alpha (GADD45a), a constitutively expressed gene activated by cellular injuries resulting in DNA damage or cell cycle arrest, is one such gene with intense upregulation in response to ALI. While it has no known action in the lung to date, we hypothesize that GADD45a is a viable candidate gene which confers protection against ALI. In this application, the principal investigator will study mechanisms by which GADD45a may influence acute lung injury. Specific Aim #1 will employ an animal model of both ventilator-induced and sepsis- induced ALI to test whether a GADD45a knockout strain is more susceptible to lung injury. We will characterize the spatial location of GADD45a expression within murine lung tissue, and assay murine lungs to determine whether GADD45a knockout alters the expression of inflammatory cytokines such as TNF-a, IL-6, or IL-1(3 compared to controls. Specific Aim #2 will test our hypothesis that GADD45a is a protective factor in ALI by silencing GADD45a in a cell culture model exposed to cyclic stretch or endotoxin, and evaluating the effect on endothelial cell barrier function. We will also explore the dominant mechanistic effect of GADD45a in ALI protection, distinguishing between putative roles in apoptosis regulation and p38 MARK inactivation. These studies will elucidate new insights into ALI pathophysiology, which may generate novel therapeutic targets for this devastating disease.