title: Investigation of the direct effects of salmon calcitonin on human osteoarthritic chondrocytes.
abstract: BACKGROUND
  Calcitonin has been demonstrated to have chondroprotective effects under pre-clinical settings. It is debated whether this effect is mediated through subchondral-bone, directly on cartilage or both in combination. We investigated possible direct effects of salmon calcitonin on proteoglycans and collagen-type-II synthesis in osteoarthritic (OA) cartilage.
  
  
  METHODS
  Human OA cartilage explants were cultured with salmon calcitonin [100 pM-100 nM]. Direct effects of calcitonin on articular cartilage were evaluated by 1) measurement of proteoglycan synthesis by incorporation of radioactive labeled 35SO4 [5 microCi] 2) quantification of collagen-type-II formation by pro-peptides of collagen type II (PIINP) ELISA, 3) QPCR expression of the calcitonin receptor in OA chondrocytes using four individual primer pairs, 4) activation of the cAMP signaling pathway by EIA and, 5) investigations of metabolic activity by AlamarBlue.
  
  
  RESULTS
  QPCR analysis and subsequent sequencing confirmed expression of the calcitonin receptor in human chondrocytes. All doses of salmon calcitonin significantly elevated cAMP levels (P < 0.01 and P < 0.001). Calcitonin significantly and concentration-dependently [100 pM-100 nM] induced proteoglycan synthesis measured by radioactive 35SO4 incorporation, with a 96% maximal induction at 10 nM (P < 0.001) corresponding to an 80% induction of 100 ng/ml IGF, (P < 0.05). In alignment with calcitonin treatments [100 pM-100 nM] resulted in 35% (P < 0.01) increased PIINP levels.
  
  
  CONCLUSIONS
  Calcitonin treatment increased proteoglycan and collagen synthesis in human OA cartilage. In addition to its well-established effect on subchondral bone, calcitonin may prove beneficial to the management of joint diseases through direct effects on chondrocytes.
authors.affiliation: Nordic Bioscience A/S, Herlev Hovedgade 207, 2730 Herlev, Denmark. bcs@nordicbioscience.com
authors.forename: Bodil-Cecilie
authors.initials: BC
authors.lastname: Sondergaard
authors.forename: Suzi H
authors.initials: SH
authors.lastname: Madsen
authors.forename: Toni
authors.initials: T
authors.lastname: Segovia-Silvestre
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Paulsen
authors.forename: Thorbjorn
authors.initials: T
authors.lastname: Christiansen
authors.forename: Christian
authors.initials: C
authors.lastname: Pedersen
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Bay-Jensen
authors.forename: Morten A
authors.initials: MA
authors.lastname: Karsdal
mesh_terms: D000368:Aged; D000818:Animals; D002116:Calcitonin / Q000494:pharmacology* / Q000627:therapeutic use; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D024043:Collagen Type II / Q000096:biosynthesis / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D010078:Oxazines; D010455:Peptides / Q000378:metabolism; D011509:Proteoglycans / Q000187:drug effects / Q000378:metabolism; D018003:Receptors, Calcitonin / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D013194:Staining and Labeling; D013462:Sulfur Radioisotopes / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D014966:Xanthenes
chemical_list: D024043:Collagen Type II; D010078:Oxazines; D010455:Peptides; D011509:Proteoglycans; D018003:Receptors, Calcitonin; D013462:Sulfur Radioisotopes; D014966:Xanthenes; C005843:resazurin; C028815:salmon calcitonin; D002116:Calcitonin; D000242:Cyclic AMP