Article Text

Download PDFPDF

AB0073 Accumulation of advanced glycation end products (AGES) in osteoarthritic cartilage is related to an impairment of the adaptative mechanism of GLYOXALASE-1
Free
  1. S Trellu1,
  2. A Courties1,
  3. S Jaisson2,
  4. B Friguet3,
  5. X Houard4,
  6. F-P Ehkirch5,
  7. C Jacques4,
  8. F Berenbaum1,
  9. J Sellam1
  1. 1UPMC Univ Paris 06, Inserm UMRS_938, Rheumatology department, AP- HP, Saint-Antoine Hospital, Paris
  2. 2University of Reims Champagne-Ardenne, UMR CNRS 7369, Laboratory of Biochemistry and Molecular Biology, Reims
  3. 3UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing-IBPS
  4. 4UPMC Univ Paris 06, Inserm UMRS_938, Saint-Antoine Hospital
  5. 5Groupe Maussins, Clinique des Maussins-Ramsay, Général de Santé, Paris, France

Abstract

Background Advanced glycation end-products (AGEs) that result from a non-enzymatic reaction between a sugar and a protein, are generated during tissular ageing. Accumulation of AGEs could also be part of the osteoarthritis (OA) process by modifying the biomechanic properties of cartilage and by inducing chondrocyte activation. Glyoxalase-1 (Glo-1) is the main enzyme involved in the removal of AGEs precursors, especially the AGE carboxymethyllysine (CML).

Objectives We aimed to quantify CML in human osteoarthritic cartilage, to investigate Glo-1 expression in chondrocytes and to study chondrocytic Glo-1 regulation in an inflammatory context.

Methods 1) Ex vivo: Osteoarthritic cartilages from patients undergoing knee replacement were collected, dissected and incubated for 24h with or without IL-1β (5ng/ml). We quantified CML in these cartilage explants using liquid chromatography and mass spectrometry, Glo-1 protein expression (Western Blot and immunohistochemistry) and Glo-1 enzymatic activity by measuring the kinetic of formation of the Glo-1 product (S-D lactoylglutathione) using spectrophotometry at 240nm during 10 minutes. 2) In vitro: Primary cultured murine chondrocytes (C57B6) were stimulated 72 h with increasing IL-1β doses (0 to 10ng/mL). Glo-1 expression was assessed by quantitative RT-PCR, Western blot and enzymatic activity. To analyze whether oxidative stress is involved in Glo-1 regulation induced by IL-1β, cells were treated with inhibitors of mitochondrial oxidative stress (MitoTEMPO) or of nitric oxide (NO) synthase (L-NAME).

Results 1) Ex vivo, CML was found in all human OA cartilage samples and its level increased according to age (correlation coefficient CML/age: r=0.78, p<0.01). In parallel to CML increase, Glo-1 protein was expressed in chondrocytes on all layers of cartilage. A positive correlation was found between Glo-1 enzymatic activity and the age of the patients (r=0.45, p<0.05) but was lost in case of incubation with IL-1β (r=-0.09, p non significant). 2) In vitro, in murine chondrocytes cultures, we observed a dose-dependent decrease of IL1β-induced Glo-1 mRNA (0.67 fold, p<0.05), protein quantity (0.56 fold, p<0.05) and enzymatic activity (0.7 fold, p<0.05) (n=5). The blockade of NO by L-NAME, and of mitochondrial oxidative stress by MitoTEMPO counteracted the downregulation of IL1β-induced Glo-1 expression and enzymatic activity (n=5).

Conclusions We show here that the age-dependent accumulation of AGEs in OA cartilage could be due to an impairment of the adaptative mechanism of Glo-1, mediated by oxidative stress. Further studies aiming at targeting Glo-1 restauration as a therapeutical strategy for ageing-related OA are needed.

Disclosure of Interest None declared

Statistics from Altmetric.com

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.