Alveolar Biology: Sex, Age, and Alveolar Turnover

描述(由申请人提供)：我们的长期目标仍然是进行实验，帮助阐明肺泡周转(形成和丢失)的调节，希望这些信息可能在治疗上有用。我们过去和建议的工作与支气管肺发育不良(BPD)和慢性阻塞性肺疾病(COPD)最为相关，BPD是一种早产儿的疾病，肺泡化受阻是其关键特征，在慢性阻塞性肺疾病中，肺泡破坏会导致大量的发病率和死亡率。COPD持续不断的肺泡破坏是无法补救的，越来越多的证据表明，女性比男性更容易受到影响，而且她们的下坡过程更快。自上次提交以来的主要新发现是：1.成年女性雌激素受体(ER)α和ERβk.o。小鼠有一种肺泡表型--比野生型小鼠更大、更少的肺泡，表面积更小。2.成年小鼠去卵巢后3周内肺泡减少45%，肺泡表面积减少13%。3.在发生肺泡丢失后，雌激素替代可挽救肺泡丢失。4.作为原理的证据，我们在成年小鼠中发现：a)鼻内滴注微量的弹性蛋白酶表面活性物质(SAM)导致严重的弥漫性肺气肿，从而显示弥漫性肺泡输送；b)单次鼻内滴注GAPDHRNAi(10-15mU/L)，与杂乱的GAPDHRNAi相比，导致GAPDHRNAi以肺特异性方式下调60%-70%，从24小时到7天；c)鼻注维甲酸(RA)SAM导致肺中一种标志性蛋白的mR NA浓度以肺特异性方式增加4.6倍；相同浓度的维甲酸腹腔注射后，肺组织标志物mRNA表达增加1.8倍，脑和其他器官表达增加。利用野生型和突变小鼠，形态计量学和肺基因表达谱，我们的具体目标是：1.确定ER肺泡表型的开始发育时间；2.识别介导卵巢切除诱导的肺泡破坏的ER；以及3.识别启动卵巢切除后雌激素诱导的肺泡再生所需的信号级联反应的上游调节因子。我们认为，自第一次修订应用程序以来产生的新信息，包括以简单、非侵入性、肺特异的方式改变特定基因表达的能力，我们在形态测量方面的丰富经验，以及现在的肺基因图谱，将使我们能够完成拟议的工作。

DESCRIPTION (provided by applicant): Our long range goal remains performing experiments that help elucidate the regulation of alveolar turnover (formation and loss) in the hope this information might be therapeutically useful. Our past, and proposed, work are most relevant to bronchopulmonary dysplasia (BPD), a condition of very prematurely born infants in which arrested alveolarization is a key feature, and chronic obstructive pulmonary disease (COPD), in which alveolar destruction causes substantial morbidity and mortality. There is no remediation for the relentlessly progressive alveolar destruction of COPD, to which increasing evidence suggests women are more susceptible than men, and in whom the downhill course is more rapid. Key new findings since the last submission are: 1. Adult female estrogen receptor (ER)alpha and ERbeta k.o. mice have an alveolar phenotype - larger and fewer alveoli with less surface area than wildtype mice. 2. Ovariectomy in adult mice results, within 3 weeks, in a loss of 45% of alveoli and 13% of alveolar surface area. 3. Estrogen replacement, after alveolar loss has occurred, rescues the loss. 4. As proof of principle, we show in adult mice a) nasal instillation of microliter (fl) amounts of elastase in surfactant (SAM) resulted in severe diffuse emphysema thereby demonstrating diffuse alveolar delivery; b) a single nasal instillation of GAPDH RNAi in SAM (10- 15mu/l), compared with scrampled GAPDH RNAi, resulted in a 60-70% down-regulation, in a lung specific manner, of GAPDH protein from 24 h through 7 days; c) nasal instillation of retinoic acid (RA) in SAM caused a 4.6-fold increase in lung concentration of the mRNA of a marker protein in a lung specific manner; an equal concentration of RA given intraperitonealy caused a 1.8-fold increase in the marker mRNA in lung and an increase in brain and other organs. Our specific aims, using wild type and mutant mice, morphometric, and lung gene-expression profiling, are: 1. Determine the developmental time of onset of the ER alveolar phenotype; 2. Identify the ERs that mediate the ovariectomy-induced destruction of alveoli, and 3. Identify the upstream modulators that initiate the signal cascade required for estrogen-induced alveolar regeneration that follows ovariectomy. We think the new information generated since the first amended application, including the ability to alter expression of specific genes in a simple, noninvasive, lung specific manner, our extensive experience with morphometry, and now with lung gene profiling, will allow us to complete the proposed work.