title: Deletion of Opg Leads to Increased Neovascularization and Expression of Inflammatory Cytokines in the Lumbar Intervertebral Disc of Mice.
abstract: METHODS
  Neovascularization and expression of inflammatory cytokines were examined in Osteoprotegerin (Opg) knockout (KO) mice that show intervertebral disc (IVD) degeneration.
  
  
  OBJECTIVE
  The aim of this study was to clarify the pathological changes in lumbar IVD degeneration in Opg KO mice.
  
  
  BACKGROUND
  Osteoporosis is a controversial risk factor for IVD degeneration. Deletion of Opg resulted in IVD degeneration in mice. Neovascularization and inflammatory cytokines are key factors in IVD degeneration.
  
  
  METHODS
  Opg KO mice and their wild-type (WT) littermates were euthanized. Lumbar IVDs were harvested. Safranin O/Fast Green staining was performed to examine the pathological changes. Microcomputed tomographic (micro-CT) analysis was performed to determine the structural changes at the junction of lumbar IVD cartilage and vertebrae. Tartrate-resistant acid phosphatase (TRAP) staining was performed to evaluate osteoclast formation. Protein expression of vascular endothelial growth factor A (VEGF-A), CD31, VE-cadherin, CD 34, interleukin-1β (IL-1β), and tumor necrosis factors α (TNF-α) were analyzed by immunohistochemistry (IHC) assays. Gene expressions of IL-1β, IL-6, and TNF-α were analyzed by real-time polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  In 12-week-old Opg KO mice, new bone was formed in the endplate cartilage of lumbar IVDs and this became more obvious in 24-week-old Opg KO mice. Three-dimensional (3D) μCT reconstruction analyses showed that the edges of the L4 and L5 vertebrae were rugged with bone marrow cavities in it. Protein expression of VEGF-A, CD31, VE-cadherin, and CD34 was increased in the endplate and growth plate of lumbar IVDs of Opg KO mice. Gene expression of IL-1β, IL-6, and TNF-α as well as protein expression of IL-1β and TNF-α were highly expressed in the lumbar IVDs of Opg KO mice.
  
  
  CONCLUSIONS
  Deletion of Opg leads to increased neovascularization and expression of inflammatory cytokines in the lumbar disc in Opg KO mice, which may play important roles in IVD degeneration.
  
  
  METHODS
  N/A.
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Li
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Chun-Chun
authors.initials: CC
authors.lastname: Xue
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Yong-Jian
authors.initials: YJ
authors.lastname: Zhao
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Shao-Dan
authors.initials: SD
authors.lastname: Cheng
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Dong-Feng
authors.initials: DF
authors.lastname: Zhao
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Liang
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Lu
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Wang
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.|Spine Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Shu
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism*; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000378:metabolism* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000473:pathology; D053244:Osteoprotegerin / Q000235:genetics* / Q000378:metabolism
chemical_list: D016207:Cytokines; D053244:Osteoprotegerin