title: Restriction of spontaneous and prednisolone-induced leptin production to dedifferentiated state in human hip OA chondrocytes: role of Smad1 and β-catenin activation.
abstract: OBJECTIVE
  The aetiology of OA is not fully understood although several adipokines such as leptin are known mediators of disease progression. Since leptin levels were increased in synovial fluid compared to serum in OA patients, it was suggested that joint cells themselves could produce leptin. However, exact mechanisms underlying leptin production by chondrocytes are poorly understood. Nevertheless, prednisolone, although displaying powerful anti-inflammatory properties has been recently reported to be potent stimulator of leptin and its receptor in OA synovial fibroblasts. Therefore, we investigated, in vitro, spontaneous and prednisolone-induced leptin production in OA chondrocytes, focusing on transforming growth factor-β (TGFβ) and Wnt/β-catenin pathways.
  
  
  METHODS
  We used an in vitro dedifferentiation model, comparing human freshly isolated hip OA chondrocytes cultivated in monolayer during 1 day (type II, COL2A1 +; type X, COL10A1 + and type I collagen, COL1A1 -) or 14 days (COL2A1 -; COL10A1 - and COL1A1+).
  
  
  RESULTS
  Leptin expression was not detected in day1 OA chondrocytes whereas day14 OA chondrocytes produced leptin, significantly increased with prednisolone. Activin receptor-like kinase 1 (ALK1)/ALK5 ratio was shifted during dedifferentiation, from high ALK5 and phospho (p)-Smad2 expression at day1 to high ALK1, endoglin and p-Smad1/5 expression at day14. Moreover, inactive glycogen synthase kinase 3 (GSK3) and active β-catenin were only found in dedifferentiated OA chondrocytes. Smad1 and β-catenin but not endoglin stable lentiviral silencing led to a significant decrease in leptin production by dedifferentiated OA chondrocytes.
  
  
  CONCLUSIONS
  Only dedifferentiated OA chondrocytes produced leptin. Prednisolone markedly enhanced leptin production, which involved Smad1 and β-catenin activation.
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium. Electronic address: edith.charlier@chu.ulg.ac.be.
authors: E
authors: E
authors: Charlier
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: O
authors: O
authors: Malaise
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: M
authors: M
authors: Zeddou
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: S
authors: S
authors: Neuville
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: G
authors: G
authors: Cobraiville
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: C
authors: C
authors: Deroyer
authors: Bone and Cartilage Research Unit, Arthropole Liège, University of Liège, Belgium.
authors: C
authors: C
authors: Sanchez
authors: Orthopedic Surgery Unit, CHU of Liège, Belgium.
authors: P
authors: P
authors: Gillet
authors: Orthopedic Surgery Unit, CHU of Liège, Belgium.
authors: W
authors: W
authors: Kurth
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: D
authors: D
authors: de Seny
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: B
authors: B
authors: Relic
authors: Laboratory of Rheumatology, GIGA Research, CHU de Liège, Arthropole Liège, University of Liège, Belgium.
authors: M G
authors: MG
authors: Malaise
mesh_terms: D030301:Activin Receptors, Type II / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D054337:Cell Dedifferentiation / Q000187:drug effects / Q000235:genetics; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D024121:Collagen Type X / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D020738:Leptin / Q000378:metabolism*; D008233:Lymphotoxin-alpha / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000235:genetics / Q000378:metabolism*; D011239:Prednisolone / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000187:drug effects / Q000378:metabolism; D051898:Smad1 Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051899:Smad2 Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051902:Smad5 Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000187:drug effects / Q000235:genetics; D051176:beta Catenin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: C495270:CTNNB1 protein, human; D024121:Collagen Type X; D050659:Core Binding Factor Alpha 1 Subunit; D005938:Glucocorticoids; D020738:Leptin; D008233:Lymphotoxin-alpha; D012333:RNA, Messenger; C493709:RUNX2 protein, human; D018125:Receptors, Transforming Growth Factor beta; C497399:SMAD1 protein, human; C497782:SMAD2 protein, human; C497797:SMAD5 protein, human; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D051898:Smad1 Protein; D051899:Smad2 Protein; D051902:Smad5 Protein; D051176:beta Catenin; D011239:Prednisolone; D017346:Protein Serine-Threonine Kinases; D038362:Glycogen Synthase Kinase 3; C425364:ACVRL1 protein, human; D030301:Activin Receptors, Type II; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13
keywords: Dedifferentiation; Hip osteoarthritis; Human chondrocytes; Leptin; Smad1; β-Catenin