Abstract:

Objective: To investigate the in vivo and in vitro transdifferentiation capacity of murine CD11c-positive dendritic cells (CD11c⁺DCs) into osteoclasts, and to compare their osteoclastogenic differentiation potential with that of CD11b-positive monocytes (CD11b⁺MNs) and bone marrow monocytes (BMMs). Methods: A periodontitis model was established in C57BL/6 mice using silk ligation. Immunofluorescence staining was performed to examine the expression of CD11c and CD11b on cathepsin K (CTSK)-positive multinucleated cells in alveolar bone tissue on days 1, 3, and 7 post-surgery. Primary murine CD11c⁺DCs and CD11b⁺MNs were isolated using immunomagnetic beads, and the expression of relevant cell surface markers was detected by flow cytometry. CD11c⁺DCs, CD11b⁺MNs, and BMMs were separately cultured and induced to differentiate into osteoclasts. Tartrate-resistant acid phosphatase (TRAP) staining and real-time quantitative polymerase chain reaction (RT-qPCR) were employed to assess the number of osteoclasts formed and the mRNA expression levels of osteoclast-related genes (Ctsk, Mmp9, Trap, and Nfatc1). Results: Immunofluorescence showed that CD11c expression was significantly upregulated in alveolar bone following periodontitis surgery, with a faster rate and greater trend of upregulation compared to CD11b. On day 7 post-surgery, the proportion of CD11c⁺CTSK⁺ multinucleated cells among CTSK⁺ multinucleated cells was significantly higher than that of CD11b⁺CTSK⁺ multinucleated cells. Flow cytometry revealed that sorted CD11c⁺ DCs exhibited low expression of CD80, CD86, and MHC-Ⅱ, while CD11b⁺ MNs highly expressed Ly6C and F4/80 and did not express B220. In vitro experiments demonstrated that CD11c⁺ DCs formed a significantly greater number of TRAP-positive multinucleated cells compared to CD11b⁺ MNs and BMMs, with significantly elevated mRNA expression levels of osteoclast-related genes, including Ctsk, Mmp9, and Trap. Conclusion: Murine CD11c⁺DCs possess significant osteoclastogenic differentiation capacity and participate in the formation of CTSK⁺ multinucleated cells in periodontitis.

Key words: dendritic cells, CD11c, osteoclasts, osteoclastogenic differentiation, periodontitis

摘要：

目的： 探究小鼠CD11c阳性树突状细胞（CD11c⁺ dendritic cells，CD11c⁺DCs）在体内及体外条件下转分化为破骨细胞的能力，并比较其与CD11b阳性单核细胞（CD11b⁺ monocytes，CD11b⁺MNs）、骨髓单核细胞（bone marrow monocytes，BMMs）的破骨向分化差异。方法： 采用丝线结扎法建立C57BL/6小鼠牙周炎模型，免疫荧光法检测术后第1、3、7天牙槽骨组织中组织蛋白酶K（cathepsin K，CTSK）阳性多核细胞表面CD11c和CD11b的表达。采用免疫磁珠法分选小鼠原代CD11c⁺DCs和CD11b⁺MNs，并用流式细胞术鉴定其细胞表面标志物。分别对CD11c⁺DCs、CD11b⁺MNs和BMMs进行破骨向分化诱导，通过抗酒石酸酸性磷酸酶（tartrate-resistant acid phosphatase，TRAP）染色法和实时定量聚合酶链反应（real-time quantitative polymerase chain reaction，RT-qPCR）检测破骨细胞形成数量及破骨相关基因Ctsk、Mmp9、Trap、Nfatc1的mRNA表达。结果： 免疫荧光染色结果显示牙周炎术后牙槽骨中CD11c表达显著上调，且上调速率和趋势高于CD11b；术后第7天，CTSK⁺多核细胞中，CD11c⁺CTSK⁺多核细胞占比明显高于CD11b⁺CTSK⁺多核细胞。流式细胞术显示，分选后的CD11c⁺DCs低表达CD80、CD86和MHC-Ⅱ；CD11b⁺MNs高表达Ly6C和F4/80，不表达B220。体外实验显示，CD11c⁺DCs诱导后形成的TRAP阳性多核细胞数量显著多于CD11b⁺MNs和BMMs，且破骨相关基因Ctsk、Mmp9、Trap的mRNA表达水平显著升高。结论： 小鼠CD11c⁺DCs具有显著的破骨向分化能力，并参与牙周炎中CTSK⁺多核细胞的形成。

关键词: 树突状细胞, CD11c, 破骨细胞, 破骨向分化, 牙周炎

CLC Number: 

• 树突状细胞

• CD11c

• 破骨细胞

• 破骨向分化

• 牙周炎

• dendritic cells

• CD11c

• osteoclasts

• osteoclastogenic differentiation

• periodontitis