Putuo District People's Hospital, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China; Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Department of Endocrinology, Changchun People's Hospital, Changchun, China.
Int Immunopharmacol. 2021 Jan;90:107137. doi: 10.1016/j.intimp.2020.107137. Epub 2020 Nov 14.
Excessive activity of osteoclasts causes many bone-related diseases, such as rheumatoid arthritis and osteoporosis. Agrimophol (AGR), a phenolic compound, originated from Agrimonia pilosa Ledeb. In prior studies, AGR is reported to possess schistosomicidal and mycobactericidal activities. However, no reports covered its anti-osteoclastogenesis characteristic. In this study, we found that AGR inhibited RANKL-induced osteoclastogenesis, bone-resorption, F-actin ring formation, and the mRNA expression of osteoclast-associated genes such as CTSK, TRAP, MMP-9, and ATP6v0d2 in vitro. In addition, AGR suppressed RANKL-induced expression of c-Fos and NFATc1. However, AGR treatment did not affect NF-κB activation and MAPKs phosphorylation in RANKL-stimulated BMMs, which implicated that AGR might not influence the initial expression of NFATc1 mediated by NF-κB and MAPKs signaling. Our results further indicated that AGR did not alter phosphorylation levels of GSK3β and the expression of calcineurin, which implicated that AGR treatment might not interfere with phosphorylation and de-phosphorylation of NFATc1 mediated by GSK3β and calcineurin, respectively. B-lymphocyte-induced maturation protein-1 (Blimp1), which was regarded as a transcriptional repressor of negative regulators of osteoclastogenesis, was markedly attenuated in the presence of AGR, leading to the enhanced expression of B-cell lymphoma 6 (Bcl-6). Meanwhile, Blimp1 knockdown in BMMs by siRNA strongly enhanced the expression of Bcl6 and reduced NFATc1 induction by RANKL. These findings suggested that AGR inhibited RANKL-induced osteoclast differentiation through Blimp1-Bcl-6 signaling mediated modulation of NFATc1 and its target genes. Consistent with these in vitro results, AGR exhibited a protective influence in an in vivo mouse model of LPS-induced bone loss by suppressing excessive osteoclast activity and attenuating LPS-induced bone destruction. Hence, these results identified that AGR could be considered as a potential therapeutic agent against bone lysis disease.
破骨细胞过度活跃会导致许多与骨骼相关的疾病，如类风湿关节炎和骨质疏松症。獐牙菜苦苷（AGR）是一种酚类化合物，来源于獐牙菜属植物。在之前的研究中，AGR 被报道具有杀血吸虫和杀分枝杆菌的活性。然而，尚无报道涵盖其抗破骨细胞生成特性。在这项研究中，我们发现 AGR 抑制了 RANKL 诱导的破骨细胞生成、骨吸收、F-肌动蛋白环形成，以及 CTSK、TRAP、MMP-9 和 ATP6v0d2 等破骨细胞相关基因的 mRNA 表达。此外，AGR 抑制了 RANKL 诱导的 c-Fos 和 NFATc1 的表达。然而，AGR 处理并不影响 RANKL 刺激的 BMMs 中 NF-κB 的激活和 MAPKs 的磷酸化，这表明 AGR 可能不会影响 NFATc1 由 NF-κB 和 MAPKs 信号介导的初始表达。我们的结果进一步表明，AGR 不会改变 GSK3β 的磷酸化水平和钙调神经磷酸酶的表达，这表明 AGR 处理可能不会干扰 GSK3β 和钙调神经磷酸酶介导的 NFATc1 的磷酸化和去磷酸化。B 淋巴细胞诱导成熟蛋白-1（Blimp1），被认为是破骨细胞生成负调控因子的转录抑制因子，在 AGR 存在的情况下明显减弱，导致 B 细胞淋巴瘤 6（Bcl-6）的表达增强。同时，用 siRNA 在 BMMs 中敲低 Blimp1 强烈增强了 Bcl6 的表达，并减少了 RANKL 诱导的 NFATc1 诱导。这些发现表明，AGR 通过 Blimp1-Bcl-6 信号介导的 NFATc1 及其靶基因的调节抑制了 RANKL 诱导的破骨细胞分化。与这些体外结果一致，AGR 通过抑制破骨细胞过度活跃和减轻 LPS 诱导的骨破坏，在 LPS 诱导的小鼠骨丢失模型中表现出保护作用。因此，这些结果表明 AGR 可被视为一种治疗骨溶解疾病的潜在治疗剂。
