Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is up-regulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown. We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air–liquid interface cultures stimulated with interleukin (IL)13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse-transcription polymerase chain reaction, Western blot, histology, and functional analyses of barrier integrity. Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL13 in differentiated cells. LOX-overexpressing organoids showed suppressed basal and up-regulated differentiation markers. In addition, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified an enriched bone morphogenetic protein (BMP) signaling pathway compared with wild-type organoids. In particular, LOX overexpression increased BMP2 and decreased the BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells. Our data support a model whereby LOX exhibits noncanonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of the BMP pathway in the esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

中文翻译：

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赖氨酰氧化酶调节嗜酸性食管炎的上皮分化和屏障完整性

嗜酸性粒细胞性食管炎 (EoE) 中的上皮破坏包括分化受损和屏障完整性降低。我们发现，赖氨酰氧化酶 (LOX)（一种胶原蛋白交联酶）在 EoE 患者的食管上皮中表达上调。然而，LOX 在食管上皮中的功能作用仍不清楚。我们使用白细胞介素 (IL)13 刺激的 3 维类器官和气液界面培养物研究了 LOX 在人食管上皮中的作用，以重现 EoE 炎症环境，然后进行单细胞 RNA 测序、定量逆转录聚合酶链反应、蛋白质印迹、组织学和屏障完整性的功能分析。对患者来源的类器官的单细胞 RNA 测序分析表明，LOX 是由分化细胞中的 IL13 诱导的。 LOX 过表达的类器官表现出基础分化标记物受到抑制且分化标记物上调。此外，LOX 过表达增强了连接蛋白基因和跨上皮电阻。 LOX 过度表达可恢复受损的分化和屏障功能，包括在 IL13 刺激的情况下。对 LOX 过表达类器官的转录组分析发现，与野生型类器官相比，骨形态发生蛋白 (BMP) 信号通路更加丰富。特别是，LOX 过度表达会增加 BMP2 并减少 BMP 拮抗剂卵泡抑素。最后，我们发现BMP2处理恢复了基底细胞和分化细胞的平衡。我们的数据支持这样一个模型，即 LOX 通过激活食管中的 BMP 通路，作为一种信号分子，在炎症环境中发挥非典型作用，对上皮稳态非常重要。 LOX/BMP 轴可能是食管上皮分化中不可或缺的一部分，也是未来治疗的一个有希望的目标。