Department of Orthopaedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China.
Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China.
J Cell Biochem. 2018 Feb;119(2):2084-2093. doi: 10.1002/jcb.26370. Epub 2017 Sep 18.
Naringenin (NAR) is a natural predominant flavanone and has a wide range of pharmacological activities. The aim of this study was to investigate the protective mechanisms of NAR on RANKL-induced osteoclastogenesis and osteoclast bone resorption. T cells were divided into four groups under different concentrations of NAR (0, 25, 50, 100 µM). CD4 T cell subsets in different groups were evaluated by flow cytometry. TRAP staining, pit formation assays and F-actin ring immunofluorescent staining were performed. In addition, gene expression of osteoclast-specific markers was analyzed by qPCR and Western blot. Our results showed that compared with the control group, there were relatively fewer Th1 and Th17 cells and more Th2 cells and Treg cells in the NAR groups. Besides, the number of TRAP-positive multinucleated osteoclasts, the areas of bone resorption pits and the size and number of F-actin rings were notably decreased in the bone marrow macrophages (BMMs) treated with T-cell supernatant containing NAR. Moreover, NAR treatment dramatically reduced the expressions of cathepsin K, c-Fos, DC-STAMP, NFATc1, TRAP, and V-ATPase d2 at mRNA and protein levels. However, these effects were abolished by adding a neutralizing antibody against IL-4. In conclusion, NAR suppressed RANKL-induced osteoclastogenesis and osteoclast bone resorption by promoting the release of IL-4 from T cells.
柚皮素（NAR）是一种天然存在的主要类黄酮，具有广泛的药理活性。本研究旨在探讨 NAR 对 RANKL 诱导的破骨细胞生成和破骨细胞骨吸收的保护机制。T 细胞在不同浓度的 NAR（0、25、50、100μM）下分为四组。通过流式细胞术评估不同组别的 CD4 T 细胞亚群。进行 TRAP 染色、陷窝形成测定和 F-actin 环免疫荧光染色。此外，通过 qPCR 和 Western blot 分析破骨细胞特异性标志物的基因表达。结果表明，与对照组相比，NAR 组 Th1 和 Th17 细胞相对较少，而 Th2 细胞和 Treg 细胞较多。此外，含有 NAR 的 T 细胞上清液处理的骨髓巨噬细胞（BMM）中 TRAP 阳性多核破骨细胞数量、骨吸收陷窝面积以及 F-actin 环的大小和数量均显著减少。此外，NAR 处理显著降低了 mRNA 和蛋白水平的组织蛋白酶 K、c-Fos、DC-STAMP、NFATc1、TRAP 和 V-ATPase d2 的表达。然而，添加抗 IL-4 中和抗体后，这些作用被消除。综上所述，NAR 通过促进 T 细胞释放 IL-4 来抑制 RANKL 诱导的破骨细胞生成和破骨细胞骨吸收。
