PT  - JOURNAL ARTICLE
AU  - YASUNOBU TAMAKI
AU  - YUYA TAKAKUBO
AU  - TOMOYUKI HIRAYAMA
AU  - YRJÖ T. KONTTINEN
AU  - STUART B. GOODMAN
AU  - MITSUNORI YAMAKAWA
AU  - MICHIAKI TAKAGI
TI  - Expression of Toll-like Receptors and Their Signaling Pathways in Rheumatoid Synovitis
AID  - 10.3899/jrheum.100732
DP  - 2011 May 01
TA  - The Journal of Rheumatology
PG  - 810--820
VI  - 38
IP  - 5
4099  - http://www.jrheum.org/content/38/5/810.short
4100  - http://www.jrheum.org/content/38/5/810.full
SO  - J Rheumatol2011 May 01; 38
AB  - Objective.Toll-like receptors (TLR) recognizing endogenous and exogenous danger signals could play a role in rheumatoid arthritis (RA). Our aim was to describe the presence, localization, and extent of expression of TLR and their adapters. Methods.TLR 1, 2, 3, 4, 5, 6, and 9 receptors, and myeloid differentiation primary response protein 88, Toll/interleukin receptor (TIR) domain-containing adapter protein MyD88 adapter-like, and TIR domain-containing adapter-inducing interferon/TIR-containing adapter molecule-1 adapters were analyzed in RA (n = 10) and osteoarthritis (OA; n = 5) samples using real-time polymerase chain reaction (PCR). Their colocalization with cellular markers CD68, CD15, CD3, CD4, CD8, CD20, dendritic cell lysosomal-associated membrane protein (DC-LAMP), CD123, and 5B5 was analyzed in double immunofluorescence staining. Results.In RA, ß-actin standardized messenger RNA of TLR 2, 3, and 9 (p < 0.001) were particularly high. TLR 5 and 6 were also elevated (p < 0.05), but TLR 1 and 4 and adapters did not differ between RA and OA. In double-staining, TLR and adapters were strongly labeled in myeloid and plasmacytoid dendritic cells (DC), moderately in CD68+ type A lining cells/macrophages, and weakly to moderately in 5B5+ type B lining cells/fibroblasts. CD3+/CD4+ and CD3+/CD8+ T cells and CD20+ B cells in perivenular areas and in lymphoid follicles were moderately TLR- and weakly adapter-positive. In OA, TLR and adapters were weakly immunolabeled in vascular, lining, and inflammatory cells. Conclusion.RA synovium showed abundant expression of TLR. RA synovitis tissue seems to be responsive to TLR ligands. DC, type A cells/macrophages, and type B cells/fibroblasts are, in that order from highest to lowest, equipped with TLR, suggesting a hierarchical responsiveness. In RA, danger-associated molecular patterns to TLR interactions may particularly drive DC to autoinflammatory and autoimmune cascades/synovitis.