Cellular Senescence in Neonatal Airways

摘要 早产儿中(&lt；60%)O2(高氧)可促进支气管气道高反应性(AHR) 通过对呼吸道平滑肌(ASM)的影响，这是一种也导致支气管扩张受损的细胞类型，以及 重塑(增殖，细胞外基质改变)。从而了解通过哪些机制 氧气影响支气管呼吸道对脆弱人群的治疗策略至关重要。我们专注于 ASM中一种新的靶向机制：细胞衰老(SEN)。Sen细胞是长期存活的，并能分泌 促进炎症和纤维化的因子(衰老相关分泌表型；SASP) 对幼稚细胞的旁分泌作用。吸引力在于能杀死感觉神经细胞的新药，如 Dasatanib+Quercetin(D+Q)和Fisetin。关于围产期呼吸道中的Sen细胞知之甚少，但我们的数据 提示适量氧气可增加人胎儿ASM(FASM)的有害感受性，从而增加炎症、促进 促进幼稚ASM增殖和ECM的纤维化SASP：D+Q抑制作用。我们发现ROS 和内质网应激促进FASM Sen，以及暴露于O2(导致AHR和纤维化)的新生小鼠 D+Q可减轻O2的影响。因此，我们假设围产期氧气会导致有害的Sen细胞负荷， 通过SASP，启动和促进AHR和重塑：感觉剂缓解的效果。我们建议3个 利用人胎肺和体内新生小鼠O2模型：目的1：通过以下方式确定机制 哪种高氧诱导细胞SEN在人类ASM发育中的作用；目的2：确定细胞SEN在 高氧对人ASM发育的影响；目标3：确定有害Sen对收缩和 新生儿高氧小鼠模型的重塑。在目标1和目标2中，我们将使用18-22周的妊娠人类 FASM和肺切片研究SEN诱导的机制，重点是ROS，线粒体和内质网应激 (目标1)SEN/SASP在收缩和重塑方面的下游效应(目标2)如下 40%氧气。探索了感觉剂D+Q或鱼腥草素(目标1，2)的缓解作用。体外研究被整合在 新生小鼠模型(目标3)，其中SEN的程度被评估，并缓解呼吸道高反应性和 测试了感觉剂的重塑作用。临床意义在于确立氧对人体的有害影响 为未来新生儿哮喘的治疗靶向发展呼吸道。

ABSTRACT Moderate (<60%) O2 (hyperoxia) in premature infants promotes bronchial airway hyperresponsiveness (AHR) via effects on airway smooth muscle (ASM), a cell type that also contributes to impaired bronchodilation, and remodeling (proliferation, altered extracellular matrix (ECM)). Thus understanding mechanisms by which O2 affects bronchial airways is critical for therapeutic strategies in a vulnerable population. We focus on a novel, targetable mechanism in ASM: cellular senescence (Sen). Sen cells are long-living, and secrete factors (senescence-associated secretory phenotype; SASP) that promote inflammation and fibrosis via paracrine effects on naïve cells. Appeal lies in novel drugs that kill Sen cells (senolytics) such as dasatanib+quercetin (D+Q) and fisetin. Little is known regarding Sen cells in perinatal airways but our data indicate moderate O2 enhances detrimental Sen in human fetal ASM (fASM) with increased inflammatory, pro- fibrotic SASP that promotes proliferation and ECM of naïve ASM: effects inhibited by D+Q. We find that ROS and ER stress promote fASM Sen, and in newborn mice exposed to O2 (which results in AHR and fibrosis) D+Q alleviates O2 effects. Thus, we hypothesize perinatal O2 induces detrimental Sen cell burden that, via SASP, initiates and promotes AHR and remodeling: effects alleviated by senolytics. We propose 3 Aims using human fetal lung and in vivo neonatal mouse models of O2: Aim 1: Determine mechanisms by which hyperoxia induces cellular Sen in developing human ASM; Aim 2: Determine the role of cellular Sen in hyperoxia effects on developing human ASM; Aim 3: Determine effects of detrimental Sen on contractility and remodeling in mouse model of neonatal hyperoxia. In Aims 1 and 2, we will use 18-22 wk gestation human fASM and lung slices to examine mechanisms of Sen induction, focusing on ROS, mitochondria and ER stress (Aim 1) and downstream effects of Sen/SASP in the context of contractility and remodeling (Aim 2) following 40% O2. Alleviation by senolytics D+Q or fisetin (Aim 1, 2) are explored. In vitro studies are integrated in the newborn mouse model (Aim 3) where extent of Sen is assessed, and alleviation of airway hyperreactivity and remodeling by senolytics are tested. Clinical significance lies in establishing detrimental Sen in O2 effects on developing airway towards future therapeutic targeting for neonatal asthma.