Neurotrophins in the Lung

描述（由申请人提供）：哮喘中的气道重塑涉及纤维化增加、气道平滑肌（ASM）增殖和迁移。炎症驱动重塑，但ASM通过分泌因子、调节细胞外基质（ECM）组成和增强增殖/迁移积极地做出贡献。因此，了解炎症产生重塑的机制是新的治疗策略的关键。我们之前的资助周期强调了神经营养因子脑源性神经营养因子（BDNF）的新作用，表明BDNF增强了ASM [Ca 2 +]I和收缩性，增强了炎症的影响。我们现在的研究表明，ASM不仅是BDNF的靶点，也是BDNF的来源。该基金首次更新的重点是了解哮喘患者气道结构和功能的炎症诱导变化中ASM源性BDNF的自分泌/旁分泌作用。根据初步数据，我们认为BDNF是重塑的关键参与者。在这里，BDNF可能与基质金属蛋白酶（MMP）MMP-2和MMP-9有关，因为它们在切割分泌的BDNF中起作用，并且BDNF相反地调节MMP的数据有限。我们认为，BDNF和MMPs形成了一个相互作用的，由炎症引发的前馈回路，并且BDNF介导和调节炎症对ECM产生和ASM增殖/迁移的影响。与哮喘相关的初步数据显示，在哮喘人气道和过敏性哮喘小鼠模型中，BDNF表达和对重塑的影响增强。因此，我们的总体假设是ASM衍生的BDNF是哮喘炎症诱导的气道重塑的中心，影响ECM成分和ASM增殖和迁移。在所提出的研究中，我们将通过四个具体目的来测试这一主题：目的1：检查炎症增强人气道中的表达和释放的机制;目的2：检查炎症增强人ASM对ECM产生影响的机制;目的3：为了检测ASM-衍生的BDNF，衍生的BDNF增强对人ASM增殖和迁移的炎症作用;目的4：在混合变应原小鼠模型中检测改变的BDNF信号传导对气道重塑的体内作用。目的1-3将利用来自轻度或中度哮喘患者与非哮喘患者的人类上皮剥脱的ASM组织和细胞来检查细胞因子（TNF？与IL-13）增强BDNF（Aim 1），重叠与不同的信号传导机制，通过其介导和调节细胞因子对MMP-2和MMP-9、ECM蛋白纤连蛋白和胶原蛋白的作用（Aim 2），以及在改变ECM组成的情况下增强ASM增殖和迁移（Aim 3）。体外数据将在Aim 4中的混合变应原小鼠哮喘模型中进行体内整合，其中BDNF受体活化将在转基因TrkB敲入小鼠中被抑制。我们研究的临床意义在于，可能有一种对重塑具有多效性作用的“上游”机制，可以限制哮喘的这种不可逆特征。ASM源性BDNF

DESCRIPTION (provided by applicant): Airway remodeling in asthma involves increased fibrosis, airway smooth muscle (ASM) proliferation and migration. Inflammation drives remodeling, but ASM actively contributes by secreting factors, regulating extracellular matrix (ECM) composition and enhancing proliferation/migration. Accordingly, understanding mechanisms by which inflammation produces remodeling is key to novel therapeutic strategies. Our previous grant cycle highlighted the novel role of the neurotrophin brain-derived neurotrophic factor (BDNF), showing that BDNF enhances ASM [Ca2+]I and contractility, potentiating the effects of inflammation. Our studies now show that ASM is not only a target, but also a source of BDNF. The focus of the first renewal of this grant is to understand the autocrine/paracrine role of ASM-derived BDNF in inflammation-induced changes to airway structure and function in the context of asthma. Based on preliminary data, we believe that BDNF is a key player in remodeling. Here, BDNF may be linked to the matrix metalloproteinases (MMPs) MMP-2 and MMP-9, given their role in cleaving secreted BDNF, and limited data that BDNF conversely regulates MMPs. We propose that BDNF and MMPs form a mutually interactive, feed-forward loop stoked by inflammation, and that BDNF mediates and modulates inflammation effects on ECM production and ASM proliferation/migration. Relevant to asthma, preliminary data show that BDNF expression and effects on remodeling are enhanced in asthmatic human airway, and in a mouse model of allergic asthma. Accordingly, our overall hypothesis is that ASM-derived BDNF is central to inflammation-induced airway remodeling in asthma, affecting ECM composition and ASM proliferation and migration. In the proposed studies, we will test this theme via four Specific Aims: Aim 1: To examine mechanisms by which inflammation enhances expression and release in human airways; Aim 2: To examine the mechanisms by which potentiates inflammation effects on ECM production by human ASM; Aim 3: To examine ASM-derived BDNF ASM-derived BDNF the mechanisms by which ASM-derived BDNF potentiates inflammation effects on human ASM proliferation and migration; Aim 4: To examine in vivo effects of altered BDNF signaling on airway remodeling in a mixed allergen mouse model. Aims 1-3 will utilize human epithelium-denuded ASM tissues and cells from mild or moderate asthmatics vs. non-asthmatics to examine cytokine (TNF¿ vs. IL-13) enhancement of BDNF (Aim 1), overlapping vs. distinct signaling mechanisms by which mediates and modulates cytokine effects on MMP-2 and MMP-9, the ECM proteins fibronectin and collagen (Aim 2), and enhancement of ASM proliferation and migration in the setting of altered ECM composition (Aim 3). In vitro data will be integrated in vivo in Aim 4 in a mixed allergen mouse asthma model where BDNF receptor activation will be inhibited in a transgenic TrkB knockin mouse. The clinical significance of our studies lies in the potential that an "upstream" mechanism with pleiotropic effects on remodeling can be targeted to limit this irreversible feature of asthma. ASM-derived BDNF