Oral submucous fibrosis (OSF) is a chronic and inflammatory mucosal disease caused by betel quid chewing, which belongs to oral potentially malignant disorders. Abnormal fibroblast differentiation leading to disordered collagen metabolism is the core process underlying OSF development. The epithelium, which is the first line of defense against the external environment, can convert external signals into pathological signals and participate in the remodeling of the fibrotic microenvironment. However, the specific mechanisms by which the epithelium drives fibroblast differentiation remain unclear. In this study, we found that Arecoline-exposed epithelium communicated with the fibrotic microenvironment by secreting exosomes. MiR-17-5p was encapsulated in epithelial cell-derived exosomes and absorbed by fibroblasts, where it promoted cell secretion, contraction, migration and fibrogenic marker (α-SMA and collagen type I) expression. The underlying molecular mechanism involved miR-17-5p targeting Smad7 and suppressing the degradation of TGF-β receptor 1 (TGFBR1) through the E3 ubiquitination ligase WWP1, thus facilitating downstream TGF-β pathway signaling. Treatment of fibroblasts with an inhibitor of miR-17-5p reversed the contraction and migration phenotypes induced by epithelial-derived exosomes. Exosomal miR-17-5p was confirmed to function as a key regulator of the phenotypic transformation of fibroblasts. In conclusion, we demonstrated that Arecoline triggers aberrant epithelium-fibroblast crosstalk and identified that epithelial cell-derived miR-17-5p mediates fibroblast differentiation through the classical TGF-β fibrotic pathway, which provided a new perspective and strategy for the diagnosis and treatment of OSF.

口腔粘膜下纤维化（OSF）是一种因咀嚼槟榔引起的慢性炎症性粘膜疾病，属于口腔潜在恶性疾病。成纤维细胞分化异常导致胶原蛋白代谢紊乱是 OSF 发育的核心过程。上皮是抵御外界环境的第一道防线，可以将外界信号转化为病理信号，参与纤维化微环境的重塑。然而，上皮驱动成纤维细胞分化的具体机制仍不清楚。在这项研究中，我们发现暴露于槟榔碱的上皮通过分泌外泌体与纤维化微环境进行沟通。 MiR-17-5p 被包裹在上皮细胞来源的外泌体中并被成纤维细胞吸收，促进细胞分泌、收缩、迁移和纤维化标志物（α-SMA 和 I 型胶原）表达。潜在的分子机制涉及 miR-17-5p 靶向 Smad7 并通过 E3 泛素化连接酶 WWP1 抑制 TGF-β 受体 1 (TGFBR1) 的降解，从而促进下游 TGF-β 通路信号传导。用 miR-17-5p 抑制剂处理成纤维细胞可逆转上皮源性外泌体诱导的收缩和迁移表型。外泌体 miR-17-5p 被证实是成纤维细胞表型转化的关键调节因子。总之，我们证明了槟榔碱触发了异常的上皮-成纤维细胞串扰，并确定了上皮细胞来源的miR-17-5p通过经典的TGF-β纤维化途径介导成纤维细胞分化，这为诊断和治疗提供了新的视角和策略。开放空间基金会。