Longhua Hospital, University of Traditional Chinese Medicine at Shanghai, Shanghai, China.
Pathology, University of Alabama at Birmingham, Birmingham, Alabama.
J Cell Biochem. 2020 Jan;121(1):152-164. doi: 10.1002/jcb.28994. Epub 2019 Jul 18.
Postmenopausal women undergo rapid bone loss, which caused by the accelerated osteoclastic bone resorption. Receptor activator of nuclear factor kappa-B ligand (RANKL) plays critical and essential roles on varied stages of osteoclastogenesis. Oleanolic acid (OA), a naturally derived small compound, has been found suppress osteoclastogenesis in early stage of bone marrow macrophages (BMMs). However, whether OA also regulates the late stage of osteoclastogenesis remains unclear. Here, the regulatory effect of OA on the late stage of osteoclastogenesis was investigated in vitro using RANKL-pretreated BMMs and in vivo using osteoprotegerin (OPG) knockout mice. Our in vitro studies demonstrate that OA inhibits the late stage of osteoclastogenesis from RANKL-pretreated BMMs. For in vivo animal investigation, OA attenuates the bone loss phenotypes in OPG-knockout mice by decreasing the densities of osteoclast, which are in consistent with the finding with in vitro osteoclastogenesis. Mechanistic investigations found that OA largely inhibit the activity of c-Fos and Nuclear factor of activated T-cells c1 (NFATc1) with RANKL-pretreated BMMs and OPG-knockout mice. Furthermore, OA suppresses the activities of osteoclast genes, such as Tartrate resistant acid phosphatase (TRAP), CathepsinK (Ctsk), and Matrix metalloproteinase 9 (MMP9). Taken together these findings, they have not only defined an inhibitory effect of OA in the late stage of osteoclastogenesis but have also gained new molecular mechanisms underlying the process of osteoclast formation.
绝经后妇女经历快速的骨质流失，这是由于破骨细胞的骨吸收加速所致。核因子κB 受体激活剂配体（RANKL）在破骨细胞生成的各个阶段都发挥着关键和必要的作用。齐墩果酸（OA）是一种天然衍生的小分子化合物，已被发现可在骨髓巨噬细胞（BMMs）的早期阶段抑制破骨细胞生成。然而，OA 是否也调节破骨细胞生成的晚期阶段尚不清楚。在此，使用 RANKL 预处理的 BMMs 在体外和使用骨保护素（OPG）敲除小鼠在体内研究了 OA 对破骨细胞生成晚期的调节作用。我们的体外研究表明，OA 抑制了来自 RANKL 预处理的 BMMs 的破骨细胞生成的晚期阶段。对于体内动物研究，OA 通过降低破骨细胞的密度来减轻 OPG 敲除小鼠的骨质流失表型，这与体外破骨细胞生成的研究结果一致。机制研究发现，OA 很大程度上抑制了 RANKL 预处理的 BMMs 和 OPG 敲除小鼠中 c-Fos 和激活 T 细胞核因子 c1（NFATc1）的活性。此外，OA 抑制了破骨细胞基因的活性，如抗酒石酸酸性磷酸酶（TRAP）、组织蛋白酶 K（Ctsk）和基质金属蛋白酶 9（MMP9）。总之，这些发现不仅定义了 OA 在破骨细胞生成晚期的抑制作用，还获得了破骨细胞形成过程的新分子机制。
