FRI0052 The cox/prostaglandin-E2 pathway is critical for autocrine IL-17A production by TH17 cells upon synovial fibroblast interaction. (23rd January 2014)

• Record Type: Journal Article
• Authors: Paulissen, S.M.J.; van Hamburg, J.P.; Davelaar, N.; Asmawidjaja, P.S.; Hazes, J.M.W.; Lubberts, E.
• Is Part Of: Annals of the rheumatic diseases. Volume 71(2012)Supplement 3
• Page Start: 326
• Page End: 327
• Publication Date: 2014-01-23
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2012-eular.2509
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Recently, the authors have shown that Th17, but not Th1 cells, from patients with early rheumatoid arthritis (RA) are potent activators of synovial fibroblasts (RASF) resulting inautocrine IL-17A production. This IL-17A production results in a pro-inflammatory loop, which is characterized by an up-regulation in pro-inflammatory cytokines and cartilage degrading enzymes. The autocrine IL-17A production by Th17 cells is critical for the perseverance of the pro-inflammatory loop, but the mechanism underlying the autocrine IL-17A induction is unclear. Objectives: To investigate the mechanism responsible for the autocrine IL-17A induction upon Th17-RASF interaction. Methods: CD4+CD45RO+CCR6+ (Th17) and CD4+CD45RO+CCR6- (Th1) cells were isolated by FACS sorting from healthy controls and early RA patients. These cells were co-cultured with RASF, in the presence of neutralizing antibodies directed against soluble IL-6R (anti-sIL-6R) and/or IL-1b, and celecoxib. Gene expression profiles were generated and supernatant was collected for cytokine analyses by ELISA. Results: Gene expression analysis revealed that the genes encoding for IL-6 and IL-1b were up-regulated in Th17-RASF cultures. These data were confirmed by ELISA and Q-PCR, respectively. Since IL-1b and IL-6 may be involved in IL-17/Th17 polarization we examined the contribution of these cytokines on the autocrine IL-17A loop.Blockade of IL-1b and IL-6 activity, but not TNF-α significantly suppressed IL-17A production in the co-culture, but the inhibitory effects were limited.Of note, the combination of anti-IL-1b and anti-sIL-6R markedly suppressed IL-17F. No effects were found on IFN-γ. Interestingly, the genes encoding for cyclo-oxygenase-2 (COX-2) and prostaglandin-E-synthase (PTGES), which are involved in prostaglandin-E2 (PGE2 ) synthesis, were also up-regulated in Th17-RASF cultures. This was associated with a dramatic increase of PGE2 production in Th17-RASF cultures compared to Th1-RASF cultures. Treatment of Th17-RASF cultures with celecoxib, an inhibitor of cyclo-oxygenase-2 (COX-2) activity, resulted in a significant decrease of IL-17A, but not of IFN-g and TNF-a production. Furthermore, the decrease in IL-17A production caused by celecoxib treatment was much more pronounced compared to neutralizing IL-1 and IL-6 activity. Flow cytometry revealed a decrease in Th17 cells in celecoxib treated co-cultures, while no effects on Th1 or Th2 cells were found. Moreover, celecoxib treatment significantly inhibited the pro-inflammatory loop as less induction of IL-6, IL-8 and MMP-3 production was observed in the Th17-RASF co-cultures. Conclusions: These findings show the critical role of the COX/PGE2 pathway in the autocrine IL-17A production upon Th17 and synovial fibroblast interaction.Inhibition of this pathway down-regulates the pro-inflammatory feedback loop induced by Th17-RASF interaction leading to less production of pro-inflammatory cytokines and destructive mediators. Disclosure of Interest: None Declared