Sphingosine-1-phosphate (S1P) is an important lipid mediator that regulates a diverse range of intracellular cell signaling pathways that are relevant to tissue engineering and regenerative medicine. However, the precise function of S1P in dental pulp stem cells (DPSCs) and its osteogenic differentiation remains unclear. We here investigated the function of S1P/S1P receptor (S1PR)-mediated cellular signaling in the osteogenic differentiation of DPSCs and clarified the fundamental signaling pathway. Our results showed that S1P-treated DPSCs exhibited a low rate of differentiation toward the osteogenic phenotype in association with a marked reduction in osteogenesis-related gene expression and AKT activation. Of note, both S1PR1/S1PR3 and S1PR2 agonists significantly downregulated the expression of osteogenic genes and suppressed AKT activation, resulting in an attenuated osteogenic capacity of DPSCs. Most importantly, an AKT activator completely abrogated the S1P-mediated downregulation of osteoblastic markers and partially prevented S1P-mediated attenuation effects during osteogenesis. Intriguingly, the pro-inflammatory TNF-α cytokine promoted the infiltration of macrophages toward DPSCs and induced S1P production in both DPSCs and macrophages. Our findings indicate that the elevation of S1P under inflammatory conditions suppresses the osteogenic capacity of the DPSCs responsible for regenerative endodontics.

1-磷酸鞘氨醇 (S1P) 是一种重要的脂质介质，可调节与组织工程和再生医学相关的多种细胞内细胞信号通路。然而，S1P 在牙髓干细胞 (DPSCs) 中的确切功能及其成骨分化仍不清楚。我们在此研究了 S1P/S1P 受体 (S1PR) 介导的细胞信号在 DPSCs 成骨分化中的功能，并阐明了基本的信号通路。我们的结果表明，S1P 处理的 DPSCs 向成骨表型的分化率较低，这与成骨相关基因表达和 AKT 活化的显着降低有关。值得注意的是，S1PR1/S1PR3 和 S1PR2 激动剂均显着下调成骨基因的表达并抑制 AKT 活化，导致DPSCs的成骨能力减弱。最重要的是，AKT 激活剂完全消除了 S1P 介导的成骨细胞标志物的下调，并部分阻止了成骨过程中 S1P 介导的衰减效应。有趣的是，促炎性 TNF-α 细胞因子促进巨噬细胞向 DPSCs 浸润，并在 DPSCs 和巨噬细胞中诱导 S1P 产生。我们的研究结果表明，炎症条件下 S1P 的升高抑制了负责再生牙髓的 DPSC 的成骨能力。促炎性 TNF-α 细胞因子促进巨噬细胞向 DPSCs 浸润，并在 DPSCs 和巨噬细胞中诱导 S1P 产生。我们的研究结果表明，炎症条件下 S1P 的升高抑制了负责再生牙髓的 DPSC 的成骨能力。促炎性 TNF-α 细胞因子促进巨噬细胞向 DPSCs 浸润，并在 DPSCs 和巨噬细胞中诱导 S1P 产生。我们的研究结果表明，炎症条件下 S1P 的升高抑制了负责再生牙髓的 DPSC 的成骨能力。