Department of Food Science and Nutrition and Korean Institute of Nutrition, Hallym University, Chuncheon, Korea.
Department of Food Science and Nutrition and Korean Institute of Nutrition, Hallym University, Chuncheon, Korea.
Phytomedicine. 2020 Dec;79:153351. doi: 10.1016/j.phymed.2020.153351. Epub 2020 Sep 20.
Since enhanced bone resorption due to osteoclast differentiation and activation cause skeletal diseases, there is a growing need in therapeutics for combating bone-resorbing osteoclasts. Botanical antioxidants are being increasingly investigated for their health-promoting effects on bone. Edible Cirsium setidens contains various polyphenols of linarin, pectolinarin, and apigenin with antioxidant and hepatoprotective effects.
This study aimed to determine whether linarin present in Cirsium setidens water extracts (CSE) and its aglycone acacetin inhibited osteoclastogenesis of RANKL-exposed RAW 264.7 murine macrophages for 5 days.
This study assessed the osteoprotective effects of CSE, linarin and acacetin on RANKL-induced differentiation and activation of osteoclasts by using MTT assay, TRAP staining, Western blot analysis, bone resorption assay actin ring staining, adhesion assay and immunocytochemical assay. This study explored the underlying mechanisms of their osteoprotection, and identified major components present in CSE by HPLC analysis.
Linarin and pectolinarin were identified as major components of CSE. Nontoxic linarin and acacetin as well as CSE, but not pectolinarin attenuated the RANKL-induced macrophage differentiation into multinucleated osteoclasts, and curtailed osteoclastic bone resorption through reducing lacunar acidification and bone matrix degradation in the osteoclast-bone interface. Linarin and acacetin in CSE reduced the transmigration and focal contact of osteoclasts to bone matrix-mimicking RGD peptide. Such reduction was accomplished by inhibiting the induction of integrins, integrin-associated proteins of paxillin and gelsolin, cdc42 and CD44 involved in the formation of actin rings. The inhibition of integrin-mediated actin ring formation by linarin and acacetin entailed the disruption of TRAF6-c-Src-PI3K signaling of bone-resorbing osteoclasts. The functional inhibition of c-Src was involved in the loss of F-actin-enriched podosome core protein cortactin-mediated actin assembly due to linarin and acacetin.
These observations demonstrate that CSE, linarin and acacetin were effective in retarding osteoclast function of focal adhesion to bone matrix and active bone resorption via inhibition of diffuse cloud-associated αvβ3 integrin and core-linked CD44.
由于破骨细胞分化和激活导致的骨吸收增强会引起骨骼疾病，因此需要开发治疗方法来对抗骨吸收的破骨细胞。植物抗氧化剂因其对骨骼的促进健康作用而受到越来越多的关注。食用蓟含有各种圣草素、佩枯二林和芹菜素的多酚，具有抗氧化和保肝作用。
本研究旨在确定蓟水提取物（CSE）中的圣草素及其苷元 acacetin 是否能抑制 RANKL 暴露的 RAW 264.7 鼠巨噬细胞 5 天的破骨细胞生成。
本研究通过 MTT 测定、TRAP 染色、Western blot 分析、骨吸收试验 actin 环染色、黏附试验和免疫细胞化学试验，评估 CSE、圣草素和 acacetin 对 RANKL 诱导的破骨细胞分化和激活的骨保护作用。本研究通过 HPLC 分析鉴定 CSE 中的主要成分，探讨其骨保护作用的潜在机制。
鉴定出 CSE 的主要成分为圣草素和佩枯二林。无毒的圣草素和 acacetin 以及 CSE，但不是佩枯二林，可减弱 RANKL 诱导的巨噬细胞向多核破骨细胞分化，并通过减少破骨细胞在骨基质模拟 RGD 肽上的溶酶体酸化和骨基质降解来抑制破骨细胞的骨吸收。CSE 中的圣草素和 acacetin 减少了破骨细胞向骨基质的迁移和局灶性接触到骨基质模拟 RGD 肽。这种减少是通过抑制整合素、整合素相关蛋白 paxillin 和凝胶蛋白、参与 actin 环形成的 cdc42 和 CD44 的诱导来实现的。圣草素和 acacetin 通过破坏破骨细胞的 TRAF6-c-Src-PI3K 信号转导，抑制整合素介导的 actin 环形成。由于圣草素和 acacetin 的作用，c-Src 的功能抑制导致富含 F-肌动蛋白的 podosome 核心蛋白 cortactin 介导的 actin 组装丢失。
这些观察结果表明，CSE、圣草素和 acacetin 通过抑制弥散云相关的αvβ3 整合素和核心连接的 CD44，有效延缓破骨细胞对骨基质的黏附功能和活性骨吸收。
