Background Acute Serum Amyloid A (A-SAA) is strongly expressed in rheumatoid arthritis (RA) synovial tissue (ST) and is critically involved in regulating cell migration and invasion. In this study we examine the effect of A-SAA on Notch and chemokine signalling pathways and examine if these effects are mediated through TLR2 activation.
Methods Expression of Notch 1 IC, downstream target genes HRT1, HRT2 and ligands JAGGED 1 and DLL-4 were assessed in synovial tissue and cells by Real-Time PCR and Western blot. Human microvascular endothelial cells (HMVEC) and primary Rheumatoid Arthritis Synovial Fibroblasts (RASFC) were cultured in the presence of anti-TLR2 or IgG control antibody. IL-6, IL-8, GROα and MCP-1 were assessed by ELISA, EC activation was assessed by matrigel tube formation and invasion assays. MMP expression in HMVEC and RASFC was assessed by real-time PCR, ELISA and gelatin zymography.
Results NOTCH-1, target genes HRT 1, HRT 2 and ligands JAGGED 1 and DLL-4 mRNA was demonstrated in RA and PsA synovial biopsies. A-SAA significantly induced Notch-1 IC protein expression (p<0.05), and HRT 1 and JAGGED 1 mRNA expression (p<0.05). In contrast DLL-4 mRNA was significantly inhibited in response to A-SAA (p<0.05). A-SAA significantly induced IL-6, IL-8, GROa and MCP-1 in HMVEC and RASFC, effects which were significantly inhibited by the presence of anti-TLR2 (all p<0.05). Furthermore, A-SAA induced EC activation and invasion were inhibited by anti-TLR2 (p<0.05). Conversly the presence of TLR2 had a nominal effect on MMP mRNA and protein expression. However we observed differential effects on Notch pathway signalling components.
Conclusions TLR2 differentially mediates A-SAA induced pro-inflammatory mechanisms involved in the pathogenesis of Rheumatoid Arthritis.
Disclosure of Interest P. Rooney: None Declared, W. Gao: None Declared, J. McCormick: None Declared, L. Harty: None Declared, D. Veale Grant/Research support from: Wyeth, GSK, Abbott, Opsona, Consultant for: Wyeth, GSK, Abbott, Pfizer, Schering Plough, Centocor, Speakers Bureau: Wyeth, GSK, Abbott, Pfizer, Schering Plough, Centocor, Mundipharma, U. Fearon: None Declared, M. Connolly: None Declared
Statistics from Altmetric.com
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.