Identification of NR4A2 as a transcriptional activator of IL-8 expression in human inflammatory arthritis.

Expression of the orphan nuclear receptor NR4A2 is controlled by pro-inflammatory mediators, suggesting that NR4A2 may contribute to pathological processes in the inflammatory lesion. This study identifies the chemoattractant protein, interleukin 8 (IL-8/CXCL8), as a molecular target of NR4A2 in human inflammatory arthritis and examines the mechanism through which NR4A2 modulates IL-8 expression. In TNF-alpha-activated human synoviocyte cells, enhanced expression of IL-8 mRNA and protein correspond to temporal changes in NR4A2 transcription and nuclear distribution. Ectopic expression of NR4A2 leads to robust changes in endogenous IL-8 mRNA levels and co-treatment with TNF-alpha results in significant (p<0.001) secretion of IL-8 protein. Transcriptional effects of NR4A2 on the human IL-8 promoter are enhanced in the presence of TNF-alpha, suggesting molecular crosstalk between TNF-alpha signalling and NR4A2. A dominant negative IkappaB kinase antagonizes the combined effects of NR4A2 and TNF-alpha on IL-8 promoter activity. Co-expression of NR4A2 and the p65 subunit of NF-kappaB enhances IL-8 transcription and functional studies indicate that transactivation occurs independently of NR4A2 binding to DNA or heterodimerization with additional nuclear receptors. The IL-8 minimal promoter region is sufficient to support NR4A2 and NF-kappaB/p65 co-operative activity and NR4A2 can interact with NF-kappaB/p65 on a 39bp sequence within this region. In patients treated with methotrexate for active inflammatory arthritis, a reduction in NR4A2 synovial tissue levels correlate significantly (n=10, r=0.73, p=0.002) with changes in IL-8 expression. Collectively, these data delineate an important role for NR4A2 in modulating IL-8 expression and reveal novel transcriptional responses to TNF-alpha in human inflammatory joint disease.

Human rheumatoid arthritis tissue production of IL-17A drives matrix and cartilage degradation: synergy with tumour necrosis factor-alpha, Oncostatin M and response to biologic therapies.

INTRODUCTION: The aim of this study was to examine IL-17A in patients, following anti-TNF-alpha therapy and the effect of IL-17A on matrix turnover and cartilage degradation. METHODS: IL-17A expression was examined by ELISA and immunohistology in the rheumatoid arthritis (RA) joints. RA whole synovial tissue explant (RA ST), primary synovial fibroblasts (RASFC), human cartilage and chondrocyte cultures were stimulated with IL-17A +/- TNF-alpha and Oncostatin M (OSM). Matrix metalloproteinase (MMP) and tissue inhibitor (TIMP-1) were assessed by ELISA and zymography. Cartilage proteoglycan release was assessed histologically by Safranin-O staining. Clinical parameters, IL-17A, MMP/TIMP were assessed in patients pre/post biologic therapy. RESULTS: IL-17A levels were higher in RA vs osteoarthritis (OA)/normal joints (P < 0.05). IL-17A up-regulated MMP-1, -2, -9, and -13 in RA ST, RASFC, cartilage and chondrocyte cultures (P < 0.05). In combination with TNF-alpha and OSM, IL-17A shifted the MMP:TIMP-1 ratio in favor of matrix degradation (all P < 0.05). Cartilage proteoglycan depletion in response to IL-17A was mild; however, in combination with TNF-alpha or OSM showed almost complete proteoglycan depletion. Serum IL-17A was detected in 28% of patients commencing biologic therapy. IL-17A negative patients demonstrated reductions post therapy in serum MMP1/TIMP4, MMP3/TIMP1 and MMP3/TIMP4 ratios and an increase in CS846 (all P < 0.05). No significant changes were observed in IL-17A positive patients. CONCLUSIONS: IL-17A is produced locally in the inflamed RA joint. IL-17A promotes matrix turnover and cartilage destruction, especially in the presence of other cytokines, mimicking the joint environment. IL-17A levels are modulated in vivo, following anti-TNF therapy, and may reflect changes in matrix turnover.

Exercise and manual physiotherapy arthritis research trial (EMPART): a multicentre randomised controlled trial.

BACKGROUND: Osteoarthritis (OA) of the hip is a major cause of functional disability and reduced quality of life. Management options aim to reduce pain and improve or maintain physical functioning. Current evidence indicates that therapeutic exercise has a beneficial but short-term effect on pain and disability, with poor long-term benefit. The optimal content, duration and type of exercise are yet to be ascertained. There has been little scientific investigation into the effectiveness of manual therapy in hip OA. Only one randomized controlled trial (RCT) found greater improvements in patient-perceived improvement and physical function with manual therapy, compared to exercise therapy. METHODS AND DESIGN: An assessor-blind multicentre RCT will be undertaken to compare the effect of a combination of manual therapy and exercise therapy, exercise therapy only, and a waiting-list control on physical function in hip OA. One hundred and fifty people with a diagnosis of hip OA will be recruited and randomly allocated to one of 3 groups: exercise therapy, exercise therapy with manual therapy and a waiting-list control. Subjects in the intervention groups will attend physiotherapy for 6-8 sessions over 8 weeks. Those in the control group will remain on the waiting list until after this time and will then be re-randomised to one of the two intervention groups. Outcome measures will include physical function (WOMAC), pain severity (numerical rating scale), patient perceived change (7-point Likert scale), quality of life (SF-36), mood (hospital anxiety and depression scale), patient satisfaction, physical activity (IPAQ) and physical measures of range of motion, 50-foot walk and repeated sit-to stand tests. DISCUSSION: This RCT will compare the effectiveness of the addition of manual therapy to exercise therapy to exercise therapy only and a waiting-list control in hip OA. A high quality methodology will be used in keeping with CONSORT guidelines. The results will contribute to the evidence base regarding the clinical efficacy for physiotherapy interventions in hip OA.

Early changes in serum type II collagen biomarkers predict radiographic progression at one year in inflammatory arthritis patients after biologic therapy.

OBJECTIVE: To investigate whether short-term changes in serum biomarkers of type II collagen degradation (C2C) and types I and II collagen degradation (C1,2C), as well as the biomarker for the synthesis of type II procollagen (CPII) can predict radiographic progression at 1 year following initiation of biologic therapy in patients with inflammatory arthritis. METHODS: Serum levels of biomarkers were measured at baseline and at 1, 3, 6, 9, and 12 months after initiation of biologic therapy. A composite score reflecting changes from baseline in all 3 biomarkers (DeltaCOL) was calculated. Associations with clinical responses according to the 28-joint count Disease Activity Score and with radiographic progression according to the modified Sharp/van der Heijde score (SHS) were assessed. RESULTS: The 1-year increase in the SHS correlated with the 1-month change in C2C results (r = 0.311, P = 0.028) and the DeltaCOL score (r = 0.342, P = 0.015). Radiographic progression was predicted by increases in serum C2C at 1 month (P = 0.031). The DeltaCOL score was significantly associated with 1-year radiographic progression after 1 (P = 0.022), 3 (P = 0.015), 6 (P = 0.048), and 9 (P = 0.019) months of therapy. Clinical remission was predicted by 1-month decreases in serum levels of C2C (P = 0.008) and C1,2C (P = 0.036). By regression analysis, 1-month changes in C2C, C1,2C, and CPII levels were independently associated with, and correctly predicted radiographic outcome in, 88% of the patients. CONCLUSION: Short-term changes in serum levels of collagen biomarkers following initiation of biologic therapy may better predict long-term clinical and radiographic outcomes. These collagen biomarkers may therefore be valuable new early indicators of short-term biologic treatment efficacy in clinical trials and in individual patients with inflammatory erosive arthritis.

A role for type 1alpha corticotropin-releasing hormone receptors in mediating local changes in chronically inflamed tissue.

Peripheral corticotropin-releasing hormone (CRH) is an important regulator of localized inflammatory responses. The aim of this study is to define the pathological signaling pathways in which peripheral CRH receptor-mediated responses reside. We report that PECAM-1-expressing synovial membrane endothelial cells are the principal source of CRH receptor subtype 1alpha in chronically inflamed synovial tissue (ST). Analysis of ST from an early arthritis patient cohort (n = 9) established that expression of CRH-R1alpha significantly (P < 0.03) colocalized with PECAM-1 and E-selectin expression in vivo. Freshly excised ST explants released a mediator(s) that acts to promote CRH-R1alpha mRNA to levels present in inflamed human synovium (n = 8). We tested the ability of conditioned medium and individual inflammatory mediators to modulate CRH-R1alpha expression. Histamine selectively induced the expression of CRH-R1alpha, and these effects were mediated through the histamine receptor type 1. Ectopic expression of CRH-R1alpha in normal human endothelial and synoviocyte cells resulted in the induction of the orphan receptor NR4A2 through the reconstitution of cAMP/protein kinase A/cAMP response element-binding protein signaling and identified a role for CRH in modulating nuclear factor kappaB transcriptional activity. CRH enhanced the expression of nitric-oxide synthase (NOS III) to promote NO production from CRH-R1alpha-expressing cells. These data establish a role for CRH receptor-mediated responses in regulating vascular changes associated with chronic synovitis.

Inhibition of PGE2 production by nimesulide compared with diclofenac in the acutely inflamed joint of patients with arthritis.

OBJECTIVE: Cyclo-oxygenase (COX) exists in two isoforms, COX-1 and COX-2. COX-1 is responsible for homeostatic functions, whereas COX-2 is inducible and responsible for the inflammatory effects of prostaglandins. Nimesulide, a selective inhibitor of COX-2, has been shown to relieve pain rapidly in arthritis. We examined the effect of nimesulide on prostaglandin formation in arthritis, to evaluate if this compound gains access to the site of inflammation and whether this is required for analgesia. STUDY DESIGN: This was a single-dose, double-blind, double-dummy, parallel group study of nimesulide 100mg compared with diclofenac 50mg. METHODS: Serial sampling of synovial fluid, whole blood and plasma was performed at baseline and 0.5, 1, 2, 3 and 4 hours after drug administration. Synovial tissue was obtained by needle biopsy at completion of the study period. Synovial fluid prostaglandin E2 (PGE2) was measured by enzyme immunoassay. COX-1 and COX-2 activities in whole blood were estimated by serum thromboxane B2 (TxB2) and endotoxin-induced PGE2 concentrations respectively. Synovial tissue COX-1 and COX-2 mRNA and protein expression were studied by reverse transcriptase polymerase chain reaction and immunohistochemistry respectively. Twenty patients with acute knee inflammation on a background of arthritis of all types completed the study. RESULTS: Patients were allocated randomly to groups to receive nimesulide (n = 10) or diclofenac (n = 10). The mean (+/- SEM) plasma concentration of PGE2 in the nimesulide group decreased from 24.45 +/- 2.71 ng/mL at baseline to 1.74 +/- 2.71 ng/ mL at 2 hours. Diclofenac also inhibited PGE2, but at a later time point (28.15 +/- 2.86 ng/mL at baseline and 0.85 +/- 2.86 ng/mL at 4 hours). The mean (+/- SEM) synovial fluid concentration of PGE2 was 319 +/- 89 pg/mL before treatment; it remained unaltered over 4 hours after the administration of nimesulide or diclofenac (235 +/- 72 pg/mL). In contrast, in six patients receiving long-term treatment with nimesulide or a non-selective NSAID, synovial PGE2 was 61 +/- 24 pg/ mL, suggesting that inhibition of synovial prostaglandin formation is delayed compared with that in plasma. Nimesulide caused partial inhibition of serum TxB2 (a decrease from a mean of 268 +/- 24 ng/mL to one of 164 +/- 27 ng/mL at 2 hours), whereas diclofenac had a greater effect (a decrease from 224 +/- 33 ng/mL, to 76 +/- 27 ng/mL at 3 hours). CONCLUSIONS: Nimesulide, a COX-2 selective inhibitor, has a rapid onset of action in the blood compartment, with early inhibition of PGE2 generation, an index of COX-2 activity. In contrast, it exhibits a delay in achieving therapeutic concentrations in the synovial fluid. Thus factors other than local inhibition of prostaglandins may explain the rapid onset of analgesia that is associated with nimesulide, including a possible central mechanism of pain relief.

Identification of Naf1/ABIN-1 among TNF-alpha-induced expressed genes in human synoviocytes using oligonucleotide microarrays.

The cytokine tumor necrosis factor alpha (TNF-alpha) is a critical effector of the pathogenesis of rheumatoid arthritis (RA). We used oligonucleotide microarray (OM) analysis to assess TNF-alpha-modulated gene expression in cultured primary human synoviocytes in vitro. Genes identified include cytokines and inflammatory mediators, extracellular matrix and adhesion molecules, cell cycle and proliferation related proteins, transcription related proteins, and apoptotic mediators. OM identified 1185 differentially expressed genes in TNF-alpha-treated synoviocytes. The regulation of Nef-associated factor-1 (Naf1), an A20-binding, nuclear factor kappa B (NFkappaB) inhibitory protein was probed further given its putative role as an endogenous brake for the expression of some TNF-alpha-driven genes. Naf1 mRNA levels were higher in synovial biopsies from patients with active RA and seronegative arthropathy than in those from patients with osteoarthritis. These findings underscore the value of transcriptome analysis in cytokine-activated synoviocyte cultures in vitro as a means of identifying disease-associated genes in human arthritis, and implicate Naf1 as a potential modulator of TNF-alpha bioactivity in RA.