Preterm birth, lung innate immunity, and RSV

描述（由申请人提供）：呼吸道合胞病毒（RSV）感染是导致儿童住院的呼吸道疾病的最常见原因。早产儿特别容易感染严重的呼吸道合胞病毒。呼吸道上皮是RSV感染的初始部位，上皮细胞以及肺泡巨噬细胞（AM）和树突状细胞（DC）对先天和适应性免疫反应至关重要。然而，先天免疫基因在早产儿上皮细胞和AM-DC中的表达程度是可变的/有限的。该假设是基于上述事实和我们的初步数据，在羔羊中显示表面活性剂蛋白A和D （SP-AD）、羊β -防御素-1 （SBD-1）和toll样受体4 （TLR4）的表达有限的早产。它将在早产羔羊中进行试验，这些羔羊与人类疾病有密切的相似之处，包括易感性、病变和先天免疫。特异性Aim 1比较了关键先天免疫基因（SBD-1、SP-AD、TLR4）的表达和体内蛋白/肽的产生，以及AM-DC细胞因子在足月前和足月肺中的表达。该研究还验证了一种假设，即上皮细胞增殖和/或分化受限是SP-AD、SDB-1表达受限的机制基础，并通过比较足月前和足月培养细胞的转录活性、蛋白质/肽产量，以及有无细胞增殖和分化的情况来验证这一点。特异性Aim 2在羔羊模型和体外培养上皮细胞中验证了SP-AD、SBD-1和AM-DC对RSV的反应在足月前低于足月的假设。第二种假设，即细胞增殖和/或上皮分化增加可以防止RSV感染，将在体外用Aim 1的治疗方法进行测试。采用RNAi法检测SP-AD、SBD-1对RSV感染的直接预防程度。特异性Aim 3验证了在细胞增殖/分化过程中表达的其他先天免疫基因可以预防RSV感染的假设。该Aim使用原代极化人肺细胞的基因表达谱和呼吸上皮特异性探针组（Unigene），这是迄今为止注释和定义最完善的基因靶组。它还可以识别人类基因的绵羊同源物，并检测受损/减少的早产表达。这个团队结合了兽医和人类医学专业知识来实现这个项目的目标：发现SP-AD、SBD-1和其他先天免疫基因表达不足的原因，以及早产时易患RSV感染的AMDC反应。这项工作意义重大，因为它发现了RSV易感性早产的潜在基础和增强先天免疫的机制途径。

DESCRIPTION (provided by the applicant): Respiratory syncytial virus (RSV) infection is the most common cause of respiratory disease leading to hospitalization in children. Preterm infants are especially susceptible to severe RSV infection. Respiratory epithelium is an initial site of RSV infection and epithelial cells along with alveolar macrophages (AM) and dendritic cells (DC) are vital to innate and adaptive immune responses. However, the extent of innate immune gene expression by epithelia and AM-DC in preterm infants can be variable/limited. The hypothesis is that: Reduced innate immunity by respiratory epithelia and AM-DC preterm enhances susceptibility to RSV infection This hypothesis is based on the facts above and our preliminary data in lambs demonstrating limited expression of surfactant proteins A and D (SP-AD), sheep beta-defensin-1 (SBD-1), and Toll-like receptor 4 (TLR4) preterm. It will be tested in preterm lambs which have close similarities with human disease including susceptibility, lesions, and innate immunity. Specific Aim 1 compares expression of key innate immune genes (SBD-1, SP-AD, TLR4) and protein/peptide production in vivo as well as AM-DC cytokine expression in pre- and full-term lung. It also tests the hypothesis that limited epithelial cell proliferation and/or differentiation pre-term underlie(s) the mechanistic basis for limited SP-AD, SDB-1 expression and tests this by comparing transcriptional activity, protein/peptide production in pre- and full term cultured cells with or without cell proliferation and differentiation. Specific Aim 2 tests the hypothesis that SP-AD, SBD-1 and AM-DC responses to RSV are less at pre- than full-term in the lamb model and in vitro with cultured epithelial cells. A second hypothesis, that increased cell proliferation and/or differentiation of epithelia protects against RSV infection, will be tested in vitro with treatments from Aim 1. The extent to which SP-AD, SBD-1 directly prevent RSV infection will be tested with RNAi assays. Specific Aim 3 tests the hypothesis that yet other innate immune genes expressed with cell proliferation/differentiation prevent RSV infection. This Aim uses gene expression profiling of primary polarized human lung cells and a respiratory epithelia-specific probe set (Unigene) that is the most well-annotated and defined gene target set to date. It also identifies ovine orthologs of human genes and test for impaired/reduced expression preterm. This team combines veterinary and human medical expertise to attain the goal of this project: to discover the reason(s) for inadequate expression of SP-AD, SBD-1 and other innate immune genes as well as AMDC responses at preterm that predispose to RSV infection. The work is significant because it discovers the underlying basis for RSV susceptibility preterm and mechanistic approaches to enhance innate immunity.