Correlation of protease-activated receptor-2 expression and synovitis in rheumatoid and osteoarthritis

Tindell, A.G., Kelso, E.B., Ferrell, W.R., Lockhart, J.C., Walsh, D.A. , Dunning, L. and McInnes, I.B. (2012) Correlation of protease-activated receptor-2 expression and synovitis in rheumatoid and osteoarthritis. Rheumatology International, 32(10), pp. 3077-3086. (doi: 10.1007/s00296-011-2102-9) (PMID:21913036)

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Protease-activated receptor-2 (PAR-2) is known to be pro-inflammatory and increasing evidence points to an inflammatory component in osteoarthritis. This investigation examined the relationship between synovitis and PAR-2 expression, histological and immunohistochemical analysis being performed on synovial samples obtained from OA and RA patients, along with non-arthritic samples obtained by post mortem (PM). Samples were also analysed for PAR-4 expression, this receptor also having putative pro-inflammatory roles. Analysis involved comparison of inflammatory indices (synovial thickness and monocyte infiltration) with expression of PAR-2 and PAR-4. Synovial explants were also analysed for TNFα generation in the presence of a PAR-2 antagonist (ENMD-1068) or vehicle. OA synovia showed heterogeneity of inflammatory indicators, some samples overlapping with those from the RA cohort whilst others appeared similar to the PM cohort. PAR-2 expression, both in the lining layer and the interstitium, correlated strongly and significantly with synovial thickness (r = 0.91) and monocyte infiltration (r = 0.83), respectively (P < 0.001 in both cases), and this remains significant on individual cohort analysis. PAR-2 was co-localised to CD3 and CD68 cells in RA and OA synovium as well as fibroblasts derived from these synovia. PAR-4 was also expressed, but the relationship with inflammatory indicators was substantially weaker. Inflammatory indicators in OA synovia showed considerable variability, but correlated strongly with PAR-2 expression, suggesting PAR-2 upregulation in synovitis. Heterogeneity of inflammatory indicators was paralleled by wide variation in TNFα generation between samples. Secretion of this cytokine was dose-dependently inhibited by ENMD-1068, providing evidence of a functional role for PAR-2 in promoting synovitis.

Item Type:Articles
Glasgow Author(s) Enlighten ID:McInnes, Professor Iain and Tindell, Dr Alistair and Ferrell, Professor William and Dunning, Mrs Lynette and Walsh, Dr David and Kelso, Mrs Elizabeth and Lockhart, Professor John
Authors: Tindell, A.G., Kelso, E.B., Ferrell, W.R., Lockhart, J.C., Walsh, D.A., Dunning, L., and McInnes, I.B.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
Journal Name:Rheumatology International
ISSN (Online):1437-160X
Published Online:13 September 2011

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
441631PAR2 in the pathogenesis of osteoarthritisWilliam FerrellArthritis Research UK (ARC)MP/17728III -IMMUNOLOGY
514221PAR2 as a therapeutic target in osteoarthritisWilliam FerrellArthritis Research UK (ARC)18901III -IMMUNOLOGY