Resolution of Diffuse Inflammatory Lung Injury in Neonatal Mice

描述(申请人提供)：在美国，儿童急性肺损伤(ALI)的死亡率为22%，11%的儿童死于与ALI相关的肺炎。尽管儿童ALI相关性肺炎的发病率和死亡率很高，但对导致急性肺损伤的过程和导致肺恢复的机制知之甚少。此外，对新生儿到青春期免疫系统中与年龄相关的变化以及这些年龄差异如何影响肺对ALI的反应的了解相对较少。我们的初步研究表明，在ALI的反应中，新生儿肺内巨噬细胞-淋巴细胞的相互作用不同，特别是在TLR4激活的反应中，肺泡巨噬细胞缺乏MHC II类的上调。我们认为这可能影响了最初的炎症反应，损害了Treg在肺损伤区域的募集和增殖，从而促进了慢性肺部炎症。在成人ALI的实验模型中，Tregs已被证明是肺恢复的关键协调者。在我们的初步研究中，我们发现，过继转移C57BL/6同源CD45.1小鼠成年脾中的Tregs，而不是CD8+细胞或PBS(Sham)，可以减轻内毒素诱导的ALI新生小鼠的肺中性粒细胞减少和体重减轻。我们的初步研究还表明，Tregs可以调节ALI新生儿的肺部炎症。本项目的主要目标是研究ALI在新生儿和青少年肺中调节疾病严重程度的机制和因素。我们已经为新生小鼠开发了一种ALI模型，在该模型中，我们可以使用非侵入性的气管内途径将药物输送到肺部。使用这个模型，我们将研究ALI反应中与年龄相关的差异，以及允许恢复的机制。我们还对确定肺发育期间的脆弱时期感兴趣，在这些时期，肺损伤可以导致成人肺的持久变化。在本项目中，我们将具体：(1)表征新生儿(5日龄小鼠)和青少年(12日龄小鼠)对ALI早期和晚期炎症反应的年龄相关差异；(2)研究T调节细胞在化解新生儿和青少年ALI肺部炎症和细菌清除方面的作用；(3)确定AGE在急性肺损伤和恢复过程中对巨噬细胞-淋巴细胞相互作用的影响。我们相信，这些研究将促进在与临床ALI相关的背景下对新生儿肺反应的详细检查，并将突出 补充Tregs作为治疗新生儿ALI的一种可能的辅助治疗。

DESCRIPTION (provided by applicant): In the United States pediatric acute lung injury (ALI) has a mortality rate of 22%, with 11% of children dying from ALI-related pneumonias. Although a high morbidity and mortality is associated with pediatric ALI-related pneumonias, little is known about the processes that cause acute lung injury and the mechanisms that lead to lung recovery. Furthermore, relatively less is known about the age-related changes that occur in the immune system from neonatal to adolescence life and how these age differences affect the lungs' response to ALI. Our preliminary studies suggest differences in macrophage-lymphocyte interactions in neonatal lung in response to an ALI, specifically a lack of MHC class II upregulation in alveolar macrophages in response to TLR4 activation. We believe that this may influence the initial inflammatory response and impair recruitment and proliferation of Tregs into areas of lung injury, thus promoting chronic lung inflammation. Tregs have been shown to be critical orchestrators of lung recovery in an experimental model of adult ALI. In our preliminary studies we found that adoptive transfer of Tregs, but not CD8+ cells or PBS (sham) from adult spleen of C57BL/6 congenic CD45.1 mice attenuated lung neutrophilia and weight loss in neonatal mice with LPS-induced ALI. Our preliminary studies also suggested that Tregs can modulate lung inflammation in the neonate with ALI. The primary goal of this project is to characterize the mechanisms and factors that modulate disease severity from ALI in the neonatal and juvenile lung. We have developed a model of ALI for neonatal mice in which we can deliver an agent into the lungs using a non-invasive intra-tracheal route. Using this model we will study the age related differences that occur in response to an ALI and the mechanisms that allow for recovery. We are also interested in identifying vulnerable periods during lung development in which lung injury can cause lasting changes in the adult lung. In this project we will specifically: (1) characterize age related differences in the early and late inflammatory response to ALI in neonatal (5 day old mice) and juvenile (12 day old mice) (2) study the role of T-regulatory cells in resolving lung inflammation and bacterial clearance in neonatal and juvenile ALI and (3) determine the impact of age on macrophage-lymphocyte interactions during acute lung injury and recovery. We believe that these studies will facilitate detailed examination of neonatal lung responses in a context that is relevant to clinical ALI and will highlight a role for supplemental Tregs as a possible adjuvant therapy in the treatment of neonatal ALI.