International Immunology Advance Access originally published online on November 29, 2006
International Immunology 2007 19(2):117-126; doi:10.1093/intimm/dxl128
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TGF-ß type I receptor kinase inhibitor down-regulates rheumatoid synoviocytes and prevents the arthritis induced by type II collagen antibody
1 Department of Immunology
2 Department of Orthopaedic Surgery
3 Department of Human Pathology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
4 Atopy Research Center, Juntendo University School of Medicine, Tokyo 113-8421, Japan
Correspondence to: A. Nakao; E-mail: anakao{at}yamanashi.ac.jp
Rheumatoid arthritis (RA) is characterized by hypertrophic synovial tissues comprising excessively proliferating synovial fibroblasts and infiltrating inflammatory cells. Transforming growth factor-ß (TGF-ß) is a multifunctional cytokine that regulates cell growth, inflammation and angiogenesis by acting on various cell types. In RA synovial tissues, TGF-ß is expressed at high levels. However, the precise role of TGF-ß in RA remains unclear. We herein demonstrated a causal link between the TGF-ß-induced RA synovial cell proliferation and induction of platelet-derived growth factor (PDGF)-AA. In addition, TGF-ß induced IL-6 and vascular endothelial growth factor (VEGF) production by RA synovial fibroblasts associated with nuclear factor-kappa B activation. These effects of TGF-ß on RA synovial fibroblasts were suppressed by TGF-ß type I receptor kinase inhibitor HTS466284. Furthermore, HTS466284 significantly prevented anti-collagen type II antibody-induced arthritis in mice according to the clinical manifestations, histology, tumor necrosis factor-
, PDGF and VEGF expression and 5-bromo-2'-deoxyuridine incorporation. These in vitro and in vivo results suggest that TGF-ß plays a role in the development of synovial hyperplasia consisting of synovial cell proliferation, inflammation and angiogenesis. The blockade of TGF-ß signaling may thus become an additional strategy for the treatment of RA.
Keywords: rheumatoid arthritis