Alveolar bone is the thickened ridge of jaw bone that supports teeth. It is subject to constant occlusal force and pathogens invasion, and is therefore under active bone remodeling and immunomodulation. Alveolar bone holds a distinct niche from long bone considering their different developmental origin and postnatal remodeling pattern. However, a systematic explanation of alveolar bone at single-cell level is still lacking. Here, we construct a single-cell atlas of mouse mandibular alveolar bone through single-cell RNA sequencing (scRNA-seq). A more active immune microenvironment is identified in alveolar bone, with a higher proportion of mature immune cells than in long bone. Among all immune cell populations, the monocyte/macrophage subpopulation most actively interacts with mesenchymal stem cells (MSCs) subpopulation. Alveolar bone monocytes/macrophages express a higher level of Oncostatin M (Osm) compared to long bone, which promotes osteogenic differentiation and inhibits adipogenic differentiation of MSCs. In summary, our study reveals a unique immune microenvironment of alveolar bone, which may provide a more precise immune-modulatory target for therapeutic treatment of oral diseases.

牙槽骨是支撑牙齿的下颌骨的加厚脊。它受到持续的咬合力和病原体侵袭，因此处于主动的骨重塑和免疫调节状态。考虑到它们的发育起源和产后重塑模式不同，牙槽骨与长骨相比具有独特的优势。但是，仍然缺乏在单细胞水平上对牙槽骨的系统解释。在这里，我们通过单细胞RNA测序（scRNA-seq）构建了小鼠下颌牙槽骨的单细胞图集。在牙槽骨中发现了更活跃的免疫微环境，与长骨相比，成熟的免疫细胞所占的比例更高。在所有免疫细胞群体中，单核细胞/巨噬细胞亚群与间充质干细胞（MSCs）亚群最活跃地相互作用。与长骨相比，牙槽骨单核细胞/巨噬细胞表达更高水平的制瘤素M（Osm），这会促进成骨细胞分化并抑制MSCs的成脂分化。总之，我们的研究揭示了独特的牙槽骨免疫微环境，它可以为口腔疾病的治疗提供更精确的免疫调节靶标。