Neurotrophins in the Lung

哮喘的气道高反应性(AHR)和重塑涉及到气道平滑肌(ASM)的增加。 炎症驱动的收缩能力、质量和细胞外基质(ECM)。ASM积极促进增长 通过自分泌/旁分泌影响调节呼吸道结构/功能的因素。在之前的周期中，我们 脑源性神经营养因子(BDNF)是一种ASM源性因子，具有自分泌促进作用 ASM的收缩、增殖和纤维化。在这个范围内，我们发现了胶质源性神经营养因子 神经营养因子(GDNF)及其相关成员神经突蛋白(NRTN)作为新的呼吸道生长因子促进 炎症效应。GDNF和NRTN在神经系统中具有保护作用，但几乎没有 关于GDNF或NRTN在呼吸道生物学或哮喘，特别是ASM中的信息。初步研究表明 A)人类ASM表达和分泌GDNF和NRTN作为对激动剂的反应，并增加释放 通过肿瘤坏死因子α或转化生长因子β和哮喘的ASM；B)胶质细胞生长因子和神经营养因子受体Ret，肾小球滤过率α1和肾小球滤过率α2存在 炎症/哮喘中表达增加的ASM；C)外源性GDNF和NRTN具有多效性 对ASM的影响，增强[钙]细胞和收缩能力，促进细胞外基质的形成，以及有趣的内质网应激， 线粒体分裂、线粒体Ca~(2+)与呼吸作用；D)胶质细胞源性神经营养因子和硝酸甘油转运蛋白可通过肾小球肾素受体α1在体内相互作用 对混合过敏原(MA)小鼠哮喘模型的研究表明：1)GDNF增强呼吸道反应性；2)Ret 抑制或螯合GDNF钝化MA对AHR和重塑的影响。基于这些数据，我们提出了一种 GDNF配体家族ASM表达和自分泌信号参与AHR的总体假设 以及哮喘的重塑。我们将通过四个目标来测试这一概念，特别是关注 ASM来源的GDNF和NRTN。我们的目标是：目标1：研究上游调控机制 GDNF与NRTN在人类ASM中的比较；目的2：研究GDNF与NRTN增强ASM的机制 炎症和哮喘背景下人ASM中的钙离子/收缩能力；目的3：检查机制 在炎症和哮喘的背景下，GDNF和NRTN通过促进人ASM重塑；目的 4：在AHR和重塑的背景下，使用混合的方法检查GDNF和NRTN在体内的重要性 过敏原哮喘小鼠模型。AIMS 1-3利用人去上皮ASM组织和分离的ASM 从轻度或中度哮喘患者和非哮喘患者的细胞中检测信号机制 炎症介质通过以下途径促进GDNF/NRTN的产生(AIM 1)、受体和细胞内途径 这些配体影响收缩能力(目标2)与内质网应激、线粒体结构/功能和 增殖/细胞外基质(目标3)。目的4将MA模型应用于GDNF与NRTN增强或 抑制，特别是在平滑肌中，并探索呼吸道结构、细胞外基质成分和 机械师。临床意义在于确定ASM来源的生长因子的作用，如GDNF或 NRTN影响哮喘病理生理学的多个方面，是吸引人的治疗靶点。

Airway hyperreactivity (AHR) and remodeling in asthma involve increased airway smooth muscle (ASM) contractility, mass, and extracellular matrix (ECM) driven by inflammation. ASM actively secretes growth factors that modulate airway structure/function via autocrine/paracrine influences. In previous cycles, we identified brain-derived neurotrophic factor (BDNF) as an ASM-derived factor with autocrine enhancement of ASM contractility, proliferation and fibrosis. Within this purview, we discovered glial-derived neurotrophic factor (GDNF) and a related member neurturin (NRTN) as novel growth factors in the airway that promote inflammation effects. GDNF and NRTN have protective roles in the nervous system but there is minimal to no information on GDNF or NRTN in airway biology or asthma, particularly for ASM. Preliminary studies show that A) Human ASM expresses and secretes GDNF and NRTN in response to agonist, with increased release by TNFα or TGFβ and in asthmatic ASM; B) GDNF and NRTN receptors Ret, GFRα1 and GFRα2 are present in ASM with increased expression in inflammation/asthma; C) Exogenous GDNF and NRTN have pleiotropic effects on ASM, enhancing [Ca2+]cyt and contractility, promoting ECM formation, and intriguingly ER stress, mitochondrial fission, mitochondrial Ca2+ and respiration; D) GDNF and NRTN can interact via GFRα1. In vivo studies in mixed allergen (MA) mouse models of asthma show 1) GDNF enhances airway reactivity; 2) Ret inhibition or chelation of GDNF blunt MA effects on AHR and remodeling. Based on these data, we propose an overall hypothesis that ASM expression and autocrine signaling by GDNF ligand family contributes to AHR and remodeling in asthma. We will test this concept via four Aims, focusing particularly on the novel role of ASM-derived GDNF and NRTN. Our Aims are: Aim 1: To examine mechanisms of upstream regulation of GDNF vs. NRTN in human ASM; Aim 2: To examine mechanisms by which GDNF vs. NRTN enhance Ca2+/contractility in human ASM in the context of inflammation and asthma; Aim 3: To examine mechanisms by which GDNF vs. NRTN enhance remodeling in human ASM in the context of inflammation and asthma; Aim 4: To examine in vivo importance of GDNF vs. NRTN in the context of AHR and remodeling using a mixed allergen mouse model of asthma. Aims 1-3 utilize human epithelium-denuded ASM tissues and isolated ASM cells from mild or moderate asthmatics vs. non-asthmatics to examine signaling mechanisms by which inflammatory mediators enhance GDNF/NRTN production (Aim 1), the receptor and intracellular pathways by which these ligands influence contractility (Aim 2) vs. ER stress, mitochondrial structure/function and proliferation/ECM (Aim 3). Aim 4 applies the MA model to mice where GDNF vs. NRTN is enhanced or inhibited, particularly in smooth muscle and explores changes in airway structure, ECM composition, and mechanics. Clinical significance lies in establishing the role of ASM-derived growth factors such as GDNF or NRTN that influence multiple aspects of asthma pathophysiology and are appealing therapeutic targets.