Role of AHR, OVOL1, and SPINK7 in Eosinophilic Esophagitis

总结 本研究的长期目标是阐明嗜酸性食管炎（EoE）的免疫学特征。这 是一个重要的主题，因为EoE是一种新兴的慢性疾病，通常始于儿童时期，并持续到 成年期，并与大量的发病率，特别是其他特应性疾病正在研究中， U19提案，但没有FDA批准的疗法。理解这个问题具有重要意义， 阐明其基本免疫学特征有可能为改进诊断奠定基础 和治疗。我们的中心假设是，芳烃受体（AHR）作为食管癌的一种受体， 传感器并通过转录因子OVOL 1介导其作用，OVOL 1诱导抗蛋白酶 SPINK 7，并且IL-4和IL-13抑制该途径。这一假设的基本原理是基于以下发现： 我们目前的U19基金为丝氨酸肽酶抑制剂Kazal 7型的核心作用提供了证据， （SPINK 7）在EoE发病机制中的作用。SPINK 7的获得性缺失足以释放不受控制的食管癌 蛋白酶活性，这反过来又诱导上皮细胞分化的丧失，桥粒蛋白的丧失， 表达和屏障功能受损，以及促炎介质的过度产生，包括 TSLP。然而，对于SPINK 7表达的分子调控几乎一无所知，SPINK 7表达的分子调控是SPINK 7表达的关键。 这是这次续约的主题。我们发现食管上皮富集转录因子， 卵样转录抑制因子1（OVOL 1）调节SPINK 7启动子活性和表达。此外，委员会认为， OVOL 1过表达增加SPINK 7表达，而OVOL 1缺失减少SPINK 7，损害 上皮屏障，重要的是增加TSLP的产生。在机制上，AHR的配体诱导 OVOL 1核转位，这反过来又促进SPINK 7表达;相反，AHR拮抗剂抑制 SPINK 7表达。IL-4和IL-13降低AHR的发现揭示了与2型免疫的联系。 诱导的OVOL 1核转位和OVOL 1诱导的SPINK 7表达。此外，过度表达 CAPN 14由一个主要的EoE遗传易感性位点编码，降低OVOL 1的表达。 翻译研究表明EoE患者食管OVOL 1蛋白表达减少 阻断丝氨酸蛋白酶活性可减弱小鼠实验性EoE。这些临床意义 质子泵抑制剂奥美拉唑是一种AHR配体，用于治疗EoE， 引发SPINK 7我们将使用创新的方法，通过3个互补的目标来测试中心假设 结合了联合收割机分子、基因组和生物学研究。在目标1中，我们将测试OVOL 1在食管癌中的作用。 通过调节包括SPINK 7在内的分化基因的表达， OVOL 1对上皮分化和屏障功能至关重要。在目标2中，我们将研究以下AHR调节： SPINK 7，检验AHR是食管传感器且其机制取决于OVOL 1的假设 SPINK7在目标3中，我们将测试IL-4和IL-13是否对抗SPINK 7以及这是否通过CAPN 14发生。

Summary The long-term goal of this study is to elucidate the immunologic features of Eosinophilic Esophagitis (EoE). This is an important subject as EoE is an emerging, chronic disease that often starts in childhood and continues into adulthood and is associated with substantial morbidity, especially the other atopic diseases being studied in this U19 proposal, yet has no FDA-approved therapies. Understanding this subject has significant implications as elucidating its fundamental immunologic features has potential to lay the foundation for improved diagnostics and therapies. Our central hypothesis is that the aryl hydrocarbon receptor (AHR) serves as an esophageal sensor and mediates its action via the transcription factor OVOL1, which induces transcription of the antiprotease SPINK7, and that IL-4 and IL-13 repress this pathway. The rationale for this hypothesis is based on findings from our current U19 grant that have provided evidence for a central role of serine peptidase inhibitor Kazal type 7 (SPINK7) in EoE pathogenesis. Acquired loss of SPINK7 is sufficient to unleash uncontrolled esophageal protease activity, which in turn induces loss of epithelial cell differentiation, loss of desmosomal protein expression, and impaired barrier function, as well as overproduction of proinflammatory mediators, including TSLP. Yet, there is virtually nothing known about the molecular regulation of SPINK7 expression, which is the subject of this grant renewal. We have uncovered that the esophageal epithelial enriched transcription factor, Ovo-like transcriptional repressor 1 (OVOL1) regulates SPINK7 promoter activity and expression. Furthermore, OVOL1 overexpression increases SPINK7 expression, whereas OVOL1 depletion decreases SPINK7, impairs the epithelial barrier, and importantly increases TSLP production. Mechanistically, ligands of the AHR induce OVOL1 nuclear translocation, which in turn promotes SPINK7 expression; conversely, AHR antagonists inhibit SPINK7 expression. A link with type 2 immunity is revealed by the finding that IL-4 and IL-13 reduce AHR- induced OVOL1 nuclear translocation and OVOL1-induced SPINK7 expression. Furthermore, overexpression of CAPN14, which is encoded for by a chief EoE genetic susceptibility locus, decreases OVOL1 expression. Translational studies demonstrate a decrease in esophageal expression of OVOL1 protein in patients with EoE and blockade of serine protease activity attenuates murine experimental EoE. The clinical significance of these data are underscored by the proton pump inhibitor omeprazole, which is used to treat EoE, being an AHR ligand that induces SPINK7. We will test the central hypothesis via 3 complementary aims using innovative approaches that combine molecular, genomic, and biological studies. In Aim 1, we will test the role of OVOL1 in esophageal epithelium by regulating the expression of differentiation genes, including SPINK7, testing the hypothesis that OVOL1 is critical for epithelial differentiation and barrier function. In Aim 2, we will examine AHR regulation of SPINK7, testing the hypothesis that AHR is an esophageal sensor and that its mechanism depends upon OVOL1 and SPINK7. In Aim 3, we will test whether IL-4 and IL-13 oppose SPINK7 and whether this occurs via CAPN14.