基于RANKL-NFAT信号轴研究槐定碱治疗骨质疏松症的作用机制

Osteoporosis is a skeletal disorder characterized by reduced bone mineral density and increased fracture risk. Osteoporosis is considered to result in complications of pain and skeletal deformation. Osteoporosis, seriously endangering the health and quality of life of elderly people and consuming a lot of financial or human resources of the country and the family, is an important health problem that cannot be ignored any more. Previous results indicated that the anti-osteoporosis effect of sophoridine (15 mg/Kg/body wt) on OVX model mouse was very significant and bone morphometric measures such as BMD, Tb.N and BV/TV et al. increased obviously. Serum test found reduced bone resorption marker CTX-1 and invariable bone remodeling maker OCN, which indicated that Sophoridine suppressed osteoporosis by attenuating bone resorption. Sophoridine (15 μg/mL) could significantly suppress osteoclasts formation, which proved that sophoridine suppressed osteoporosis by attenuating osteoclasts differentiation. Although sophoridine has obvious in vivo and in vitro activities, its molecular mechanism remains unclear. In the current study, it is planned to study the anti-osteoporosis and anti-osteoclastogenesis activities of sophoridine based on Rankl-NFAT signal pathway. This research might provide an alternative therapy in preventing or treating osteoporosis.

骨质疏松症会引起骨量减少，并伴随疼痛和骨骼变形等并发症。该症严重影响中老年人的身体健康及生活质量，增加国家及家庭财力与人力负担，已是不可忽视的重要健康问题。前期研究发现，槐定碱（Sophoridine）在15mg/Kg/d剂量下，可有效治疗OVX模型小鼠骨质疏松症，治疗组动物骨密度、骨小梁数量和相对骨体积等指标显著回升。血清检验发现槐定碱显著降低血清破骨标志蛋白CTX-1，而对成骨指标蛋白OCN无影响，提示槐定碱通过抑制破骨细胞治疗骨质疏松。体外实验表明，槐定碱在15μg/mL剂量下,可有效抑制破骨细胞分化，证明槐定碱通过抑制破骨细胞治疗骨质疏松症。虽然槐定碱的体内外活性显著，但作用机制不清楚，本项目将基于RANKL-NFAT信号轴，研究槐定碱抑制破骨细胞分化，治疗骨质疏松的分子机制。本研究成果将为槐定碱的进一步开发利用提供理论基础。

成骨和破骨作用的不平衡是骨质疏松症发生的重要病理因素。破骨细胞在骨质疏松症中起着举足轻重的作用，针对破骨细胞的新疗法一直是骨质疏松领域的研究热点。通过活性筛选筛选，我们发现槐定碱具有抗骨质疏松作用，本研究旨在探讨其抗骨质疏松机制。槐定碱（15mg/kg）对去卵巢（OVX）小鼠的抗骨质疏松具有显著的治疗效果，可以明显改善骨组织形态计量学指标，抑制血源性单核细胞分化为破骨细胞，并能够显著降低破骨细胞血清标志物含量。采用QPCR、westernblot和免疫荧光技术研究槐定碱作用破骨细胞分化的信号通路，发现槐定碱在体外可抑制RANKL诱导的破骨细胞形成、破骨细胞特异性标记基因标记蛋白的上升。总而言之，槐定碱剂量和时间依赖性地阻断RANKL诱导的破骨细胞成，这种抑制效果是通过抑制ERK和c-Fos的激活以及NFATc1的诱导而实现的。