Autophagy and esophageal tissue remodeling in EoE

项目总结 食管层复层鳞状上皮由经历终末分化的增殖性基底细胞组成 在超基底细胞层。这种平衡的增殖-分化梯度是由Notch调节的 嗜酸性食管炎(EoE)是一种慢性炎症性疾病，其特征是 黏膜嗜酸性粒细胞浸润、基底细胞增生(BCH)和上皮下纤维化。BCH有助于 促进固有层重塑的屏障缺陷，最终导致纤维性食道狭窄 严重影响患者的生活质量。而食物过敏原激活的免疫细胞和细胞因子介导EoE EoE的发病机制、食道上皮生物学与EoE发病机制之间的关系尚不清楚。 正在进行的项目(R01-114436)已经确定了自噬的作用，自噬是一种高度保守的细胞应激 在EoE中，反应作为一种基本的粘膜防御机制。上皮自噬激活涉及 促炎性EoE相关细胞因子诱导的线粒体应激和活性氧 如IL-13，进而刺激BCH。BCH的特点是CD73+的基底细胞耗竭和相互作用 低Notch活性的CD73-细胞的扩张，从而限制了终末分化。IL-13促进BCH 通过抑制Notch，同时诱导以mtDNA耗竭为标志的ROS介导的线粒体(Mt)损伤。 此外，CD73-细胞可能通过非依赖Notch的上皮细胞更新来维持BCH。年的总体目标 这种竞争性的更新应用是为了阐明EoE发病机制中基础细胞命运调节的本质。 中心假说是EoE相关炎症影响基底细胞促进食道的活动 组织重塑。这一假设是基于强有力的初步数据和出版物提出的 将通过下列相互关联的具体目标来实现：(1) 阐明自噬激活如何限制EoE炎症环境中的BCH；(2)描述 EoE相关BCH的线粒体损伤；(3)揭示Notch信号如何保护组织免受损伤 EoE的重塑。目前的建议利用了一种强大的EoE小鼠模型，该模型具有鳞状上皮- 特异性自噬损害、线粒体DNA耗尽或Notch抑制与同时进行的基底细胞谱系追踪。 这些方法与来自EoE小鼠和患者活检的体外食道3D有机物质相结合 确定自噬和线粒体在基础细胞内稳态中的机制和功能作用。这些 创新研究将揭示对食道基底细胞生物学和组织重塑的新见解。使用 基因工程小鼠、3D有机化合物和患者活检，我们将为 与EoE治疗相关的新的翻译应用的开发和验证(自噬激活 和线粒体靶向抗氧化剂)。这些发现可能对EoE有直接的临床影响，并有可能 涉及自噬、上皮屏障缺陷和纤维化的其他疾病(如GERD)。

Project summary Esophageal stratified squamous epithelia comprise proliferative basal cells that undergo terminal differentiation in the suprabasal cell layer. This homeostatic proliferation-differentiation gradient is regulated by Notch signaling that is impaired in eosinophilic esophagitis (EoE), a chronic inflammatory disorder characterized by mucosal eosinophilic infiltration, basal cell hyperplasia (BCH) and subepithelial fibrosis. BCH contributes to a barrier defect that facilitates lamina propria remodeling, culminating in fibrotic esophageal strictures that severely affect patients’ quality of life. While food allergen-activated immune cells and cytokines mediate EoE pathogenesis, the relationship between esophageal epithelial biology and EoE pathogenesis remains elusive. The ongoing project (R01-114436) has established the role of autophagy, a highly conserved cellular stress response, as a fundamental mucosal defense mechanism in EoE. Epithelial autophagy activation involves mitochondrial stress and reactive oxygen species (ROS) induced by proinflammatory EoE-relevant cytokines such as IL-13, which in turn stimulate BCH. BCH features depletion of CD73+ basal cells and reciprocal expansion of CD73- cells with low Notch activity, thereby limiting terminal differentiation. IL-13 promotes BCH by inhibiting Notch while inducing ROS-mediated mitochondrial (mt) damage marked by mtDNA depletion. Moreover, CD73- cells may maintain BCH via Notch-independent epithelial renewal. The overall objective in this competing renewal application is to elucidate the nature of basal cell fate regulation in EoE pathogenesis. The central hypothesis is that EoE-related inflammation influences basal cells’ activity to promote esophageal tissue remodeling. This hypothesis has been formulated based upon strong preliminary data and publications from the applicant’s laboratory and will be pursued through the following interrelated Specific Aims: (1) To elucidate how autophagy activation limits BCH in the EoE inflammatory milieu; (2) To delineate the role of mitochondrial damage in EoE-related BCH; (3) To unravel how Notch signaling protects against tissue remodeling in EoE. The present proposal utilizes a robust murine model of EoE with squamous epithelia- specific autophagy impairment, mtDNA depletion, or Notch inhibition with concurrent basal cell lineage tracing. These approaches are coupled with ex vivo esophageal 3D organoids from EoE mice and patient biopsies to define the mechanistic and functional role of autophagy and mitochondria in basal cell homeostasis. These innovative studies will reveal novel insights into esophageal basal cell biology and tissue remodeling. With genetically engineered mice, 3D organoids and patient biopsies, we will build a comprehensive platform for the development and validation of novel translational applications related to EoE therapy (autophagy activation and mitochondria-targeted antioxidants). These findings may have direct clinical impact in EoE, and potentially other diseases (e.g. GERD) where autophagy, epithelial barrier defects and fibrosis have been implicated.