title: Achyranthes bidentata extract exerts osteoprotective effects on steroid-induced osteonecrosis of the femoral head in rats by regulating RANKL/RANK/OPG signaling.
abstract: BACKGROUND
  Steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH) presents great challenges due to the various effects of steroids on multi-system pathways involved into osteoblast differentiation, osteoblast and osteoclast apoptosis, lipid metabolism, calcium metabolism and coagulation. As one of the most frequently used herbs in Traditional Chinese Medicine formulas that are prescribed for the regulation of bone and mineral metabolism, the therapeutic effects of Achyranthes bidentata on steroid-induced ONFH remain unclear. Thus, the aim of the current study was to verify whether Achyranthes bidentata extract (ABE) can be used to prevent steroid-induced ONFH and to investigate its underlying pharmacological mechanisms.
  
  
  METHODS
  Steroid-induced ONFH rat models were established to evaluate the effects of ABE treatment on osteonecrotic changes and repair processes. Microfocal computed tomography (Micro-CT) was performed to assess the effects of ABE treatment on bone mass, microstructure, and vascularization. Then, the effects of ABE treatment on osteoclast differentiation and bone formation were also evaluated in vivo and in vitro. In addition, receptor activator of nuclear factor kappa B (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) expression in sera, femoral heads and bone marrow-derived mesenchymal stem cells (BMSCs) were detected at both protein and mRNA levels.
  
  
  RESULTS
  The ratio of empty lacuna, adipose tissue area, and adipocyte perimeter in the bone marrow were markedly lower in the ABE treatment groups than in the model group. Micro-CT evaluation indicated that ABE treatment could improve the microstructure of the trabecular bone, increase bone mineral density and promote vascularization in steroid-induced ONFH rats. Moreover, ABE treatment inhibited osteoclast differentiation and activated bone formation markers. Interestingly, OPG downregulation, RANK and RANKL upregulation, and an increased ratio of RANKL to OPG in sera and necrotic femoral head could be reversed by ABE treatment, which also effectively inhibited RANKL-induced osteoclast differentiation and regulated RANKL and OPG expression of in vitro.
  
  
  CONCLUSIONS
  ABE may prevent steroid-induced ONFH and alleviate steroid-induced bone deterioration by regulating the RANKL/RANK/OPG signaling pathway.
authors.forename: Yini
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yanqiong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Weiheng
authors.initials: W
authors.lastname: Chen
authors.forename: Chunfang
authors.initials: C
authors.lastname: Liu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Li
authors.forename: Danni
authors.initials: D
authors.lastname: Sun
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Xia
authors.initials: X
authors.lastname: Mao
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, No, 16, Nanxiaojie, Dongzhimennei, Beijing 100700, China. linna888@163.com.
authors.forename: Na
authors.initials: N
authors.lastname: Lin
mesh_terms: D029044:Achyranthes / Q000737:chemistry*; D000818:Animals; D001483:Base Sequence; D015519:Bone Density; D001846:Bone Development / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D017931:DNA Primers; D005270:Femur Head / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects; D010020:Osteonecrosis / Q000378:metabolism / Q000517:prevention & control*; D053244:Osteoprotegerin / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D011239:Prednisolone / Q000009:adverse effects*; D053245:RANK Ligand / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D053246:Receptor Activator of Nuclear Factor-kappa B; D015398:Signal Transduction
chemical_list: D017931:DNA Primers; D053244:Osteoprotegerin; D010936:Plant Extracts; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D011239:Prednisolone