AB0063 Effects of chondroitin sulfate on the gene expression profile in the inflamed synovial membrane
Authors: C. Lambert, J.-E. Dubuc, E. Montell, J. Vergès, Y. Henrotin
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Chondroitin sulfate (CS) is one the most used molecules in the management of OA. Its mechanism of action remains to be detailed. <h3>Objectives</h3> To identify the differentially expressed genes between the inflammatory (I) and normal/reactive (N/R) synovial areas using a unique ex vivo culture model and to investigate the genetic modulatory effects of CS in this model. <h3>Methods</h3> Synovial cells (SC) were isolated from OA synovial specimens from 12 patients undergoing knee replacement. The synovial membrane was dissected and SC from N/R and I areas cultured separately for a period of 7 days with or without highly purified bovine CS (200 µg/ml, Bioibérica S.A., Barcelona, Spain). Gene expression profiling was performed using Illumina's multi-sample format Human HT-12 BeadChip (Illumina Inc.). Differential analysis was performed with the BRB array tools software. Class Comparison test between N/R and I conditions, N/R and N/R-CS conditions and I and I-CS conditions was based on paired t-test where N/R and I, N/R and N/R-CS and I and I-CS were paired for each patient. The biological relevance of up- and down-regulated genes was analyses with Ingenuity Pathways Analysis (Ingenuity® Systems). <h3>Results</h3> From among 47000 probes, 18253 were filtered out. Probes with a p-value below than 0.005 were chosen and classified as up- or down-regulated ones. By this way, 465 differentially expressed genes between N/R and I areas were identified. Many inflammatory mediators appear differentially expressed. The interferon alpha-inductible protein 6 (IFI6) was the most up-regulated. We also identified the hydroxysteroid (11-beta) dehydrogenase 1 (HSD11B1), the cathepsin K (CTSK), the chemokine (C-X-C motif) ligand 1 (CXCL1) and the EBV-induced G-protein coupled receptor 2 (EBI2). The differential expression of intermediates involved in angiogenesis pathway was also revealed between N/R and I areas. Among them, R-spondin-3 (RSPO3), the secreted phopshoprotein 1 (SPP1) and aquaporin 9 (AQP9) were up-regulated whereas ADAMTS1 was down-regulated. Finally, in the Wnt signaling, RSPO3 was up-regulated unlike dickkopf homolog 3 (DKK3) which was in turn down-regulated. We next performed a class comparison test between N/R and N/R-CS in one hand and between I and I-CS the other hand. 489 genes were identified as differentially expressed genes between N/R and N/R-CS conditions while 219 genes were identified between I and I-CS conditions. In this latter, our attention was focused on the down-regulated genes. Among them, we identified a number implicated in angiogenesis and cell migration pathways. Thus, the endothelial cell-specific molecule-1 (ESM1), the Transmembrane-4-L-six-family-1 (TM4SF1), the 5'-Ectonucleotidase (NT5E) and the growth arrest-specific gene 6 (GAS6) were down-regulated by CS. <h3>Conclusions</h3> Our work demonstrates the differential gene expression profile between paired inflammatory and normal/reactive areas of synovial membrane as well as the modulatory effects of CS on gene expression in the inflammatory areas, especially regarding genes involved in both angiogenesis and cell migration. <h3>Disclosure of Interest</h3> C. Lambert: None Declared, J.-E. Dubuc: None Declared, E. Montell Employee of: BIOIBÉRICA, S.A, Barcelona, Spain; Pre-Clinical R&amp;D Manager, J. Vergès Employee of: BIOIBÉRICA, S.A, Barcelona, Spain; Medical Director, Y. Henrotin Grant/research support from: This study was supported by a grant from BIOIBÉRICA, S.A, Barcelona, Spain