Objective. To examine whether depsipeptide (FK228), a histone deacetylase (HDA) inhibitor, has inhibitory effects on the proliferation of synovial fibroblasts from rheumatoid arthritis (RA) patients, and to examine the effects of systemic administration of FK228 in an animal model of arthritis.Methods. Autoantibody-mediated arthritis (AMA) was induced in 19 male DBA/1 mice (6-7 weeks old); 10 of them were treated by intravenous administration of FK228 (2.5 mg/kg), and 9 were used as controls. The effects of FK228 were examined by radiographic, histologic, and immunohistochemical analyses and arthritis scores. RA synovial fibroblasts (RASFs) were obtained at the time of joint replacement surgery. In vitro effects of FK228 on cell proliferation were assessed by MTT assay. Cell morphology was examined by light and transmission electron microscopy. The effects on the expression of the cell cycle regulators p16INK4a and p21 WAF1/Cip1 were examined by real-time polymerase chain reaction and Western blot analysis. The acetylation status of the promoter regions of p16INK4a and p21 WAF1/Cip1 were determined by chromatin immunoprecipitation assay.Results. A single intravenous injection of FK228 (2.5 mg/ml) successfully inhibited joint swelling, synovial inflammation, and subsequent bone and cartilage destruction in mice with AMA. FK228 treatment induced histone hyperacetylation in the synovial cells and decreased the levels of tumor necrosis factor ␣ and interleukin-1␤ in the synovial tissues of mice with AMA. Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia, with excessive inflammatory cell infiltration in the joints, leading to erosion of the articular cartilage and marginal bone, with subsequent joint destruction (1). Despite an explosion of information over the last 2 decades, a detailed understanding of the mechanisms of synovial hyperplasia and inflammation is lacking. Recent reports have implicated rapid proliferation of synovial cells, overexpression of inflammatory genes, and impairment of apoptosis, which can allow the persistence of abnormal cells (2-4), in the disease process.Cyclin-dependent kinases (CDKs) are essential Dr.

The systemic administration of TSA ameliorated synovial inflammation in CAIA mice. Subsequently cartilage destruction was also suppressed by TSA, at least in part, by modulating chondrocyte gene expression.

The present study suggests that IL-4 may exert chondroprotective properties against mechanical stress-induced cartilage destruction, at least in part, by inhibiting NO production by chondrocytes.

FK228 may exhibit a therapeutic effect on RA by inhibition of angiogenesis through down-regulation of angiogenesis related factors, HIF-1alpha and VEGF.

We investigated the expression and localization of heme oxygenase-1 (HO-1) in synovial fluid and synovial tissue, and examined the stimulation of HO-1 production in rheumatoid synovial fibroblasts (RASFs). Synovial fluid samples were obtained from knee joints of 20 rheumatoid arthritis (RA) and 20 osteoarthritis (OA) patients, and concentration of HO-1 and matrix metalloproteinase-3 (MMP-3) were measured by enzyme-linked immunosorbent assay (ELISA). Synovial tissues obtained from RA or OA patients during total knee arthroplasty (TKA) were used for immunohistochemical analysis of HO-1. HO-1 production by RASFs in response to various cytokines was examined by ELISA. HO-1 levels in synovial fluid were higher in the RA group than in the OA group with significant difference (P < 0.001), and correlated with serum C-reactive protein (CRP) level (r = 0.80, P < 0.01) in the RA group. Higher levels of HO-1 were seen in the RA-L group (Larsen grade III-V) than in the RA-E (Larsen grade 0-II) group (P < 0.001). There was weak correlation between the levels of HO-1 protein and MMP-3 in synovial fluid in the RA group (r = 0.31, P < 0.01), while no positive correlation was observed in OA. Positive immunoreaction for HO-1 was observed in cells of synovial tissue including synovial fibroblasts and cells in synovial pannus. HO-1 protein levels in cultured media of RASFs were increased by stimulation by interleukin-1β at 6 h and tumor necrosis factor-alpha at 12 h, but suppressed by interferon-gamma at 12 and 24 h. These results indicated that HO-1 expression in synovial tissue might be stimulated by inflammatory cytokines. The correlation of HO-1 concentration in synovial fluid with serum CRP and MMP-3 in joint fluid indicated that HO-1 might be useful as a marker of joint inflammation in RA patients.

We investigated the expression and localization of heme oxygenase-1 (HO-1) in synovial fluid and synovial tissue, and examined the stimulation of HO-1 production in rheumatoid synovial fibroblasts (RASFs). Synovial fluid samples were obtained from knee joints of 20 rheumatoid arthritis (RA) and 20 osteoarthritis (OA) patients, and concentration of HO-1 and matrix metalloproteinase-3 (MMP-3) were measured by enzyme-linked immunosorbent assay (ELISA). Synovial tissues obtained from RA or OA patients during total knee arthroplasty (TKA) were used for immunohistochemical analysis of HO-1. HO-1 production by RASFs in response to various cytokines was examined by ELISA. HO-1 levels in synovial fluid were higher in the RA group than in the OA group with significant difference (P < 0.001), and correlated with serum C-reactive protein (CRP) level (r = 0.80, P < 0.01) in the RA group. Higher levels of HO-1 were seen in the RA-L group (Larsen grade III-V) than in the RA-E (Larsen grade 0-II) group (P < 0.001). There was weak correlation between the levels of HO-1 protein and MMP-3 in synovial fluid in the RA group (r = 0.31, P < 0.01), while no positive correlation was observed in OA. Positive immunoreaction for HO-1 was observed in cells of synovial tissue including synovial fibroblasts and cells in synovial pannus. HO-1 protein levels in cultured media of RASFs were increased by stimulation by interleukin-1β at 6 h and tumor necrosis factor-alpha at 12 h, but suppressed by interferon-gamma at 12 and 24 h. These results indicated that HO-1 expression in synovial tissue might be stimulated by inflammatory cytokines. The correlation of HO-1 concentration in synovial fluid with serum CRP and MMP-3 in joint fluid indicated that HO-1 might be useful as a marker of joint inflammation in RA patients.

We aimed to test the effect of transdermal photodynamic therapy (PDT) on synovial proliferation in vitro and in vivo, using a novel photosensitizer, ATX-S10.Na(II). Synovial fibroblasts were obtained from patients with RA (RASF). Cell viability with or without PDT was determined by MTT assay. Cell morphology was examined by light and transmission electron microscopy. DNA fragmentation was labeled by TUNEL stain. Collagen antibody-induced arthritis (CAIA) was induced in DBA/1 mice, and the effects of transdermal PDT were evaluated by clinical and histological examination. PDT showed drug concentration-dependent and laser dose-dependent cytotoxicity on RASF. TUNEL stain and TEM study revealed the induction of apoptotic cell death of RASF. Transdermal PDT significantly reduced clinical arthritis and synovial inflammation in this model of arthritis. These results suggest that transdermal PDT using ATX-S10.Na(II) might be a novel less invasive treatment strategy for small joint arthritis and tenosynovitis.