title: Icariin Prevents Cartilage and Bone Degradation in Experimental Models of Arthritis.
abstract: BACKGROUND
  Icariin (ICA) is an active compound extracted from Epimedium brevicornum Maxim. Previous reports have shown that icariin has a clinically significant therapeutic effect on rheumatoid arthritis. However, little is known about the mechanism by which icariin inhibits cartilage and bone degradation.
  
  
  METHODS
  New Zealand rabbits were immunized with antigen-induced arthritis (AIA) and treated with icariin. Joint tissues from rabbits were studied by histological analysis, transmission electron microscopy (TEM), and micro-CT. The expression levels of receptor activator of nuclear factor-B ligand (RANKL) and osteoprotegerin (OPG) in joint tissues were determined using immunohistochemistry and real-time PCR analysis.
  
  
  RESULTS
  Histological analysis and TEM sections of cartilage in the ICA treated group showed a low level of chondrocyte destruction. Micro-CT analysis showed that the bone mineral density value and bone structural level in ICA treated rabbits were significantly higher compared with those in the AIA group. Immunohistochemistry and real-time PCR analysis showed that icariin treatment reduced RANKL expression and enhanced OPG expression levels, as compared to the AIA group.
  
  
  CONCLUSIONS
  These data indicate that ICA suppresses articular bone loss and prevents joint destruction. This study also determined that ICA regulated articular bone loss in part by regulating RANKL and OPG expression.
authors.affiliation: Department of Orthopaedics and Traumatology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of TCM, Shanghai 200071, China.
authors.forename: Chen Chao
authors.initials: CC
authors.lastname: Wei
authors.affiliation: Department of Orthopaedics and Traumatology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of TCM, Shanghai 200071, China.
authors.forename: Dai Qi
authors.initials: DQ
authors.lastname: Ping
authors.affiliation: Department of Orthopaedics and Traumatology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of TCM, Shanghai 200071, China.
authors.forename: Fan Tian
authors.initials: FT
authors.lastname: You
authors.affiliation: Department of Orthopaedics and Traumatology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of TCM, Shanghai 200071, China.
authors.forename: Chen Yong
authors.initials: CY
authors.lastname: Qiang
authors.affiliation: Department of Orthopaedics and Traumatology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of TCM, Shanghai 200071, China.
authors.forename: Che
authors.initials: C
authors.lastname: Tao
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000188:drug therapy*; D001847:Bone Diseases / Q000188:drug therapy*; D002356:Cartilage / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D005419:Flavonoids / Q000627:therapeutic use*; D046529:Microscopy, Electron, Transmission; D008962:Models, Theoretical; D053244:Osteoprotegerin / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism; D011817:Rabbits
chemical_list: D005419:Flavonoids; D053244:Osteoprotegerin; D053245:RANK Ligand; C056599:icariin