Migration Of Rheumatoid Arthritis Synovial Fibroblasts Research Articles

Inhibition of PCSK6 may play a protective role in the development of rheumatoid arthritis.

To assess the effect of proprotein convertase subtilisin/kexin type 6 (PCSK6) in the synovial fibroblasts of rheumatoid arthritis (RA). PCSK6 is a proteinase implicated in the proteolytic activity of various precursor proteins and involved in the regulation of protein maturation. PCSK6 expression was detected in the synovial tissue of 10 patients with RA, 10 controls with osteoarthritis, and 10 controls with ankylosing spondylitis using Western blotting and quantitative real-time PCR. Genotyping of 67 tag single-nucleotide polymorphisms (SNP) was performed using an Illumina VeraCode (Illumina) microarray in a case-control study including 267 patients with RA and 160 healthy controls. Genotyping of 4 other tag SNP was performed using a TaqMan probe genotyping assay in 1056 healthy controls and 1151 patients with RA. Cultured RA synovial fibroblasts (RASF) were transfected with PCSK6 small interfering RNA to study changes in the proliferation, invasion, migration capacity, secretion of inflammatory cytokines, cell cycle, and expression profiles of the RASF. Expression of PCSK6 mRNA and protein was significantly higher in the synovial tissues of individuals with RA than in control tissues. One SNP, rs8029797, was significantly associated with RA (p = 0.011). Knockdown of PCSK6 by RNA interference significantly decreased proliferation, invasion, and migration of RASF. These changes in RASF appeared to be related to reduced tumor necrosis factor-α secretion, G0/G1 arrest, and altered expression of various proteins including those involved in angiogenesis (matrix metalloproteinase 9, nitric oxide synthase trafficking), hypoxia (hypoxia-inducible factor-α, thioredoxin domain containing 5), proliferation (chromosome 10 open reading frame 116), and inflammation [CCL7, chemokine (C-X-C motif) ligand 9, interleukin 26]. PCSK6 is upregulated in the synovial tissues of patients with RA and has a genetic effect on the risk of RA. Inhibition of PCSK6 may play a protective role in the development of RA.

Adiponectin isoforms: a potential therapeutic target in rheumatoid arthritis?

ObjectivesSeveral clinical studies have suggested the adipocytokine adiponectin is involved in the progression of rheumatoid arthritis (RA). From this point of view, adiponectin might present a new therapeutic target. However,...

Adiponectin isoforms differentially affect gene expression of rheumatoid arthritis synovial fibroblasts

Background and objectivesAdipokines are not only produced by adipose tissue. They also play an important role in rheumatoid arthritis (RA), which is associated with increased levels of adipokines in serum,...

Hypoxia upregulates angiogenesis and synovial cell migration in rheumatoid arthritis

IntroductionRheumatoid arthritis (RA) is characterised by invasion of cartilage, bone and tendon by inflamed synovium. Previous studies in our laboratory have shown that hypoxia is a feature of RA synovitis. In the present study, we investigated the consequences of hypoxia on angiogenesis and synovial fibroblast migration in RA.MethodsSynovial tissue was harvested from RA patients, and synovial membrane cells were cultured under conditions either of hypoxia (1% oxygen) or normoxia (21% oxygen). Protein levels of matrix metalloproteinases (MMPs) and angiogenic factors were measured, while RNA was extracted for PCR quantification of MMPs/tissue inhibitors of MMP (TIMPs) and angiogenic factors. Migration of RA synovial fibroblasts through collagen, and the effect of RA synovial cell supernatants in an in vitro angiogenesis assay, were utilised to determine the functional relevance of changes in mRNA/protein.ResultsWe observed upregulation under hypoxic conditions of MMPs responsible for collagen breakdown, specifically collagenase MMP-8, and the gelatinases MMP-2 and MMP-9, at both mRNA and protein levels. Increased MT1-MMP mRNA was also observed, but no effect on TIMP-1 or TIMP-2 was detected. RA fibroblast migration across collagen was significantly increased under hypoxic conditions, and was dependent on MMP activity. Furthermore, expression of angiogenic stimuli, such as vascular endothelial growth factor (VEGF), and VEGF/placental growth factor heterodimer, was also increased. Crucially, we show for the first time that hypoxia increased the angiogenic drive of RA cells, as demonstrated by enhanced blood vessel formation in an in vitro angiogenesis assay.ConclusionsHypoxia may be responsible for rendering RA synovial lining proangiogenic and proinvasive, thus leading to the debilitating features characteristic of RA.

Transforming growth factor β stimulates rheumatoid synovial fibroblasts via the type II receptor

Transforming growth factor (TGF)-beta regulates the function of fibroblasts, and has been shown to have a role in the pathogenesis of rheumatoid arthritis (RA) because several studies have demonstrated the presence of TGF-beta in the synovial tissue and synovial fluids of RA patients. In this study, we examined the expression of TGF-beta receptors in synovial fibroblasts of patients with RA and demonstrated the significance in functional responses of synovial fibroblasts to TGF-beta in this disorder. Transforming growth factor beta1 stimulated the expression of connective tissue growth factor (CTGF) in fibroblasts of patients with RA more than in those of patients with osteoarthritis (OA). Transforming growth factor beta1 induced the chemotactic migration of RA synovial fibroblasts and inhibited their proliferation significantly more than OA synovial fibroblasts. Both RA and OA synovial fibroblasts expressed detectable amounts of TGF-beta receptor type II mRNA, but the expression was higher in RA patients than in OA patients, as assessed by reverse transcriptase-polymerase chain reaction. There was no significant difference in the expression of TGF-beta receptor type I or type III in synovial fibroblasts between RA and OA patients. These results indicate that synovial fibroblasts of RA patients express the increased TGF-beta receptor type II, which is associated with altered responses to TGF-beta observed in CTGF expression, chemotaxis, and proliferation of RA synovial fibroblasts, and may have an important role in the pathogenesis of RA.

Transforming growth factor β stimulates rheumatoid synovial fibroblasts via the type II receptor

Transforming growth factor (TGF)-β regulates the function of fibroblasts, and has been shown to have a role in the pathogenesis of rheumatoid arthritis (RA) because several studies have demonstrated the presence of TGF-β in the synovial tissue and synovial fluids of RA patients. In this study, we examined the expression of TGF-β receptors in synovial fibroblasts of patients with RA and demonstrated the significance in functional responses of synovial fibroblasts to TGF-β in this disorder. Transforming growth factor β1 stimulated the expression of connective tissue growth factor (CTGF) in fibroblasts of patients with RA more than in those of patients with osteoarthritis (OA). Transforming growth factor β1 induced the chemotactic migration of RA synovial fibroblasts and inhibited their proliferation significantly more than OA synovial fibroblasts. Both RA and OA synovial fibroblasts expressed detectable amounts of TGF-β receptor type II mRNA, but the expression was higher in RA patients than in OA patients, as assessed by reverse transcriptase–polymerase chain reaction. There was no significant difference in the expression of TGF-β receptor type I or type III in synovial fibroblasts between RA and OA patients. These results indicate that synovial fibroblasts of RA patients express the increased TGF-β receptor type II, which is associated with altered responses to TGF-β observed in CTGF expression, chemotaxis, and proliferation of RA synovial fibroblasts, and may have an important role in the pathogenesis of RA.