Background/Purpose: We have recently identified the non-selective cation channel TRPV2 (transient receptor potential vanilloid subfamily, type 2 channel) as a new central mediator of arthritis and fibroblast-like synoviocyte (FLS) invasiveness. TRPV2 activation by the synthetic agonists O1821 and LER13 suppressed invasiveness of FLS from DA rats, B6 mice and RA FLS and reduced disease severity and joint damage in collagen induced arthritis (CIA) and KRN serum-induced arthritis. However, the mechanism of action of TRPV2 agonists was incompletely understood. In this study we characterized the cell signaling events and mechanisms mediating the TRPV2 suppressive activity in FLS.

Methods: FLS cell lines developed from RA patients were pre-treated with O1821 (or vehicle) for 30 minutes, followed by either a) adhesion to multiple substrates (collagen I/II/IV, fibronectin, laminin, tenascin, vitronectin or BSA), b) cell lysis for Milliplex MAPK pathway analyses or RhoA/Rac1/Cdc42 activation assay, or c) for quantification of total matrix metalloproteases (MMPs). The active form of MMP2 was quantified on a Zymogram using supernatants from FLS cultured on Matrigel. Actin filaments and pFAK localization on FLS were analyzed by immunofluorescence.

Results: O1821 significantly reduced FLS adhesion to laminin, tenascin, vitronectin, and type IV collagen suggesting an inhibitory effect on different integrins. O1821 decreased pFAK (tyr397) levels and prevented pFAK co-localization with lamellipodia. Additionally, O1821 reduced actin filament thickness inducing a disorganized filament distribution and keeping the cells in a round and non-polarized shape. O1821 prevented the formation of lamellipodia and reduced levels of activated RhoA, while the activator CN03 bypassed that effect. We detected no significant effect of O1821 on MMPs, Cdc42, Rac1, MAPK pathway phosphorylated members p38, Jnk, Erk, CREB, Akt, Stat3, Stat5, p70S6K or NFκB.

Conclusion: We describe new cellular and signaling processes regulated by TRPV2 suggesting that it suppresses RhoA activation to prevent actin filament changes required for cell mobility and invasion, including adhesion, polarization of cell morphology and the formation of lamellipodia. These observations provide new understanding into the mechanism of action of arthritis and invasion suppressive TRPV2 agonists that are being developed toward therapeutic use.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-cation-channel-trpv2-decreases-rheumatoid-arthritis-fibroblast-like-synoviocyte-invasiveness-by-inhibiting-rhoa-activation-cell-adhesion-and-actin-cytoskeleton-changes/