Vascular endothelial cells have important tissue-specific functions in fibrosis and regeneration. In the salivary gland, endothelial cells are required for proper development, but their roles within adult glands are largely unknown. To identify ligand–receptor interactions between endothelial cells and other cell types that may be important during fibrosis and regeneration, we used a reversible ductal ligation injury. To induce injury, a clip was applied to the primary ducts for 14 d, and to induce a regenerative response, the clip was subsequently removed for 5 d. To identify endothelial cell-produced factors, we used single-cell RNA sequencing of stromal-enriched cells from adult female submandibular and sublingual salivary glands. Transcriptional profiles of homeostatic salivary gland endothelial cells were compared to endothelial cells of other organs. Salivary gland endothelial cells expressed many unique genes and displayed the highest overlap in gene expression with other fenestrated endothelial cells from the colon, small intestine, and kidney. Comparison of the 14-d ligated, mock-ligated, and 5-d deligated stromal-enriched transcripts and lineage tracing revealed that endothelial cells retain their identity following ligation and recovery from injury. CellChat and NATMI were used to predict changes in ligand–receptor interactions from endothelial cells to other cells in response to ligation and deligation. CellChat and NATMI predicted that after ligation, interactions with fibroblasts, epithelial cells, and glial cells were increased, and following deligation, interactions with pericyte, glia, fibroblasts, and immune cells were increased. Some of the highest-ranked interactions predicted in ligated compared to mock endothelial cells were between glial cells via Col4a2-Cd93 and Jag2-Notch1, as well as epithelial cells via Pecam1-Cd38, while in deligated compared to ligated endothelial cells, the top interactions were between fibroblasts via Ntf3-Ntrk2, glial cells via Hspg2-Itgb1, and pericytes via Jam2-F11r. Understanding salivary gland endothelial cell signaling will inform future endothelial cell-based regenerative therapies.

中文翻译：

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唾液腺内皮细胞的单细胞转录组分析

血管内皮细胞在纤维化和再生中具有重要的组织特异性功能。在唾液腺中，内皮细胞是正常发育所必需的，但它们在成人腺体中的作用很大程度上未知。为了确定内皮细胞和其他细胞类型之间在纤维化和再生过程中可能重要的配体-受体相互作用，我们使用了可逆的导管结扎损伤。为了诱导损伤，将夹子固定在主导管上 14 天，为了诱导再生反应，随后将夹子移除 5 天。为了鉴定内皮细胞产生的因子，我们对来自成年女性下颌下和舌下唾液腺的基质富集细胞进行了单细胞 RNA 测序。将稳态唾液腺内皮细胞的转录谱与其他器官的内皮细胞进行比较。唾液腺内皮细胞表达许多独特的基因，并且与来自结肠、小肠和肾脏的其他有窗内皮细胞在基因表达上表现出最高的重叠度。14 天连接、模拟连接和 5 天去连接基质富集转录物和谱系追踪的比较表明，内皮细胞在连接和从损伤中恢复后保留其身份。CellChat 和 NATMI 用于预测内皮细胞与其他细胞的配体-受体相互作用对结扎和去结扎反应的变化。CellChat 和 NATMI 预测，结扎后，与成纤维细胞、上皮细胞和神经胶质细胞的相互作用增加，而结扎后，与周细胞、神经胶质细胞、成纤维细胞和免疫细胞的相互作用增加。与模拟内皮细胞相比，在连接中预测排名最高的一些相互作用是通过 Col4a2-Cd93 和 Jag2-Notch1 的神经胶质细胞之间，以及通过 Pecam1-Cd38 的上皮细胞之间，而在连接中与连接的内皮细胞相比，排名最高的相互作用成纤维细胞之间通过 Ntf3-Ntrk2，神经胶质细胞通过 Hspg2-Itgb1，周细胞通过 Jam2-F11r。了解唾液腺内皮细胞信号传导将为未来基于内皮细胞的再生疗法提供信息。