DPSCs Regulate Epithelial-T Cells Interactions in Oral Submucous Fibrosis

Abstract Background Oral submucous fibrosis (OSF) is a precancerous lesion characterized by fibrous tissue deposition, and the incidence is positively correlated with the degree of betel nut chewing. Prolonged betel nut chewing can damage the integrity of oral mucosal epithelium, leading to chronic inflammation and local immunological derangement, while the underlying cellular events driving fibrogenesis and dysfunction are incompletely understood. Currently, OSF has few treatment options, with limited therapeutic effectiveness. Dental pulp stem cells (DPSCs) have been recognized for their anti-inflammatory and anti-fibrosis capabilities, making them promising candidates to treat a range of immune, inflammatory, and fibrotic diseases. However, the application of DPSCs in OSF is inconclusive. Methods A human cell atlas of oral mucosal tissues using single-cell RNA sequencing to delve into the underlying mechanisms was compiled. The epithelial cells were re-clustered to observe the heterogeneity of OSF epithelial cells and the cell communication relationship with immune cells. The results were validated in vitro, in clinicopathological sections and in animal models. In vivo, the therapeutic effect and mechanism of DPSCs were characterized by histological staining, immunohistochemical staining, SEM and AFM. Results A unique epithelial cell population, Epi1.2, with proinflammatory and profibrotic functions was predominantly found in OSF. They also induced the fibrosis process in fibroblasts by interacting with T cells through the receptor-ligand crosstalk between macrophage migration inhibitory factor (MIF)-CD74 and C-X-C motif chemokine receptor 4 (CXCR4). Furthermore, we developed OSF animal models and simulated the clinical local injection process in rat buccal mucosa using DPSCs to assess their therapeutic impact and mechanism. In the OSF rat model, DPSCs demonstrated superior therapeutic effects compared with the positive control (glucocorticoids), including reducing collagen deposition and promoting blood vessel regeneration. DPSCs were mediated immune homeostasis primarily by regulating the numbers of Epi1.2 and epithelial-stromal crosstalk. Conclusions Given the current ambiguity surrounding the cause of OSF and the limited treatment options available, our work provides new insights into the mechanism of OSF and reveals the therapeutic promise of DPSCs.