Rheumatoid Arthritis: Firestein GS

Firestein GS. · No affiliation provided · Nat Clin Pract Rheumatol. · Pubmed #19098924 No free full text.

This publication has no abstract.

Firestein GS. · Division of Rheumatology, Allergy and Immunology, UCSD School of Medicine, La Jolla, California, USA. · Arthritis Res Ther. · Pubmed #15987499 links to  free full text

Abstract: Studies of cytokine expression in rheumatoid arthritis have provided key insights into the pathogenesis of disease and have offered clues for effective therapy. Patterns of T-cell products in chronic rheumatoid synovitis suggest that T helper type 1 cells contribute to the perpetuation of disease. However, there is no guarantee that the mechanisms of late disease are identical to very early rheumatoid arthritis. Evaluation of the cytokine profile at the earliest time points after onset of symptoms could identify novel targets that prevent progression to chronic arthritis.

Firestein GS. · No affiliation provided · Arthritis Rheum. · Pubmed #15334448 links to  free full text

This publication has no abstract.

Sweeney SE, Firestein GS. · University of California San Diego School of Medicine, Mail Code 0656, Division of Rheumatology, Allergy and Immunology, 9500 Gilman Drive, La Jolla, CA 92093-0656, USA. · Ann Rheum Dis. · Pubmed #17038480 No free full text.

Abstract: Orally bioavailable compounds that target key intracellular signalling molecules are receiving increasing attention for the treatment of rheumatic diseases. The mitogen activated protein (MAP) kinases are especially attractive because they regulate both cytokine production and cytokine action. The MAP kinases are expressed and activated in rheumatoid arthritis (RA) synovium. Preclinical studies using MAP kinase inhibitors are very effective in animal models of arthritis, supporting their potential utility in human disease. Although the available data suggest a rationale for MAP kinase blockade, development of drugs has been hampered by toxicity and limited efficacy. Alternative strategies, such as targeting other kinases in the cascade or development of allosteric inhibitors have been proposed. These approaches might permit effective use of MAP kinase inhibitors for the treatment of rheumatic and immune-mediated diseases.

Firestein GS. · Department of Medicine, Division of Rheumatology, Allergy, and Immunology, University of California-San Diego School of Medicine, 9500 Gilman Drive BSB, Rm. 5098, La Jolla, CA 92093, USA. · J Clin Rheumatol. · Pubmed #16357749 No free full text.

Abstract: Although much is known about the etiology and pathogenesis of rheumatoid arthritis (RA), our understanding of the immune pathways remains incomplete. The observed clinical and pathologic manifestations result from activation of several interrelated immune pathways. Current concepts of RA pathogenesis, supported by animal models, laboratory studies, and clinical observation, have reestablished and revised some of the original views. Early proposals emphasized the importance of autoantibodies and immune complexes in the initiation of RA, suggested a role for T cells in the inflammatory response characteristic of RA, and based disease perpetuation on an imbalance in the cytokine networks. We now recognize that each of these interrelated mechanisms significantly contributes to RA pathogenesis, including T cells that can help initiate and perpetuate the disease. This article reviews the major components and immune pathways involved in RA and briefly discusses the animal models that contribute to our understanding. Although a unified theory of RA pathogenesis may not be possible at this time, a paradigm is presented that considers the immune pathways that contribute to disease progression and joint destruction. These pathways may have important implications for treatment, because their modulation by biologic response modifiers (BRMs) directed toward specific targets provides benefits to patients with RA. BRMs are a new class of therapeutic agents derived from biologically active molecules and designed to modulate specific immune or inflammatory pathways. Although currently approved BRMs still have limitations, choosing an appropriate target, possibly early rather than late in the immune response, might result in new and improved therapies for RA.

Bresnihan B, Baeten D, Firestein GS, Fitzgerald OM, Gerlag DM, Haringman JJ, McInnes IB, Reece RJ, Smith MD, Ulfgren AK, Veale DJ, Tak PP, Anonymous00383. · Department of Rheumatology, St. Vincent's University Hospital, Dublin, Ireland. · J Rheumatol. · Pubmed #16331792 No free full text.

Abstract: Synovial tissue analysis has considerable potential for future randomized controlled trials (RCT). The synovial membrane is the target tissue in treatment strategies of rheumatoid arthritis and other arthropathies. Effective modulation of synovitis is critical when attempting to control symptoms and signs, to prevent joint damage, and to maintain function. In RCT, the systematic evaluation of changes in synovial tissue after commencing treatment enables identification of an early therapeutic effect, using relatively small numbers of patients. This special interest group is working on establishing the evidence to have this endpoint meet the OMERACT filter criteria.

Firestein GS, Corr M. · Division of Rheumatology, Allergy, and Immunology, Department of Medicine, University of California at San Diego, San Diego, California, USA. · J Rheumatol Suppl. · Pubmed #15693110 No free full text.

Abstract: Characterization of the K/BxN mouse model of spontaneous arthritis contributed to the rediscovery of immune complex-mediated inflammation in rheumatoid arthritis (RA). Serum from these animals can transfer joint-specific inflammation to normal mice. Fc receptors, interleukin 1, mast cells, and complement are all essential for the development of arthritis after serum transfer. In RA, additional amplifying factors have been identified, including cytokines and intracellular signaling molecules, such as mitogen-activated protein kinases and nuclear factor kappa B, that perpetuate inflammation. Understanding the autoimmune and inflammatory pathways implicated in disease has led to targeted drug development and improved clinical outcomes.

Firestein GS. · Division of Rheumatology, Allergy, and Immunology and Clinical Investigation Institute, University of California San Diego School of Medicine, 9500 Gilman Drive, San Diego, CA 92093-0656, USA. · J Clin Invest. · Pubmed #15314683 links to  free full text

Abstract: The etiology of autoimmunity in humans remains poorly defined, and animal models provide a unique opportunity to study potential autoimmune mechanisms. A novel model of autoimmune inflammatory arthritis results from a point mutation in the zeta-associated-protein of 70 kDa (ZAP-70), which causes abnormal thymic T cell selection and survival of autoreactive clones. Although the resulting clinical and pathologic abnormalities are clearly T cell-dependent, macrophage and fibroblast cytokines such as IL-1 and TNF-alpha are required for full expression of the disease. The studies of Hata et al. raise the intriguing possibility that traditional proinflammatory cytokine networks represent common effector mechanisms in inflammatory joint diseases such as rheumatoid arthritis. Hence, effective therapeutic interventions can target either unique etiologic pathways related to adaptive immune responses or shared terminal mechanisms.

Sweeney SE, Firestein GS. · Division of Rheumatology, Allergy, and Immunology, University of California-San Diego, UCSD School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093, USA. · Curr Opin Rheumatol. · Pubmed #15103250 No free full text.

Abstract: PURPOSE: Signal transduction pathways are the intracellular mechanism by which cells respond and adapt to environmental stress. Understanding the critical networks in diseases like rheumatoid arthritis can potentially identify novel therapeutic targets. RECENT FINDINGS: Dissecting the complex pathways involved in rheumatoid synovitis, including mitogen-activated protein kinases, NF-kB, tumor suppressors, Janus kinases, the signal transducer and activator of transcription, suppressors of cytokine stimulation, and toll-like receptors may lead to new approaches to inflammatory arthritis. For instance, targeting NF-kB via IkB kinase 2 with specific inhibitors may block an array of proinflammatory cytokines that contribute to synovitis. Inhibition of Janus kinases and p38 could block metalloproteinase expression and protect the extracellular matrix. Overexpression of suppressors of cytokine stimulation and inhibition of signal transducer and activator of transcription are additional approaches that have demonstrated efficacy in animal models of arthritis. Tumor suppressor proteins and cell cycle inhibitors represent additional targets with unexpected anti-inflammatory activities. Recent evidence also suggests that targeting toll-like receptors may regulate cytokine expression in rheumatoid arthritis. SUMMARY: Multiple signal transduction pathways have been implicated in rheumatoid arthritis, and preclinical models have confirmed the therapeutic potential of small molecule inhibitors. Orally bioavailable inhibitors of the mitogen-activated protein kinase and NF-kB pathways have been designed and are currently being evaluated. Many other pathways could be targeted and offer new therapeutic options for rheumatoid arthritis.

Sweeney SE, Firestein GS. · Division of Rheumatology, Allergy, and Immunology, UCSD School of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. · Int J Biochem Cell Biol. · Pubmed #14687914 No free full text.

Abstract: Rheumatoid arthritis (RA) is a systemic, inflammatory autoimmune disorder that presents as a symmetric polyarthritis associated with swelling and pain in multiple joints, often initially occurring in the joints of the hands and feet. Articular inflammation causes activation and proliferation of the synovial lining, expression of inflammatory cytokines, chemokine-mediated recruitment of additional inflammatory cells, as well as B cell activation with autoantibody production. A vicious cycle of altered cytokine and signal transduction pathways and inhibition of programmed cell death contribute to synoviocyte and osteoclast mediated cartilage and bone destruction. A combination of targeted interventions at various stages in the pathogenesis of RA will likely be required to control symptoms in certain patients with this complex and potentially disabling disease. The regulation of rheumatoid synovial inflammation will be reviewed, followed by a brief summary of the therapeutic implications of these advances, including strategies targeting key cytokines, signal transduction molecules, co-stimulatory molecules, B cells, chemokines, and adhesion molecules.

Hammaker D, Sweeney S, Firestein GS. · Division of Rheumatology, Allergy and Immunology, UCSD School of Medicine, La Jolla, CA 92093, USA. · Ann Rheum Dis. · Pubmed #14532158 links to  free full text

Abstract: Signal transduction pathways regulate cellular responses to stress and play a critical role in inflammation. The complexity and specificity of signalling mechanisms represent major hurdles for developing effective, safe therapeutic interventions that target specific molecules. One approach is to dissect the pathways methodically to determine their hierarchy in various cell types and diseases. This approach contributed to the identification and prioritisation of specific kinases that regulate NF-kappa B and the mitogen activated protein (MAP) kinase cascade as especially attractive targets. Although significant issues remain with regard to the discovery of truly selective kinase inhibitors, the risks that accompany inhibition of fundamental signal transduction mechanisms can potentially be decreased by careful dissection of the pathways and rational target selection.

Firestein GS. · Division of Rheumatology, Allergy and Immunology, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0656, USA. · Nature. · Pubmed #12748655 No free full text.

Abstract: Rheumatoid arthritis is the most common inflammatory arthritis and is a major cause of disability. It existed in early Native American populations several thousand years ago but might not have appeared in Europe until the 17th century. Early theories on the pathogenesis of rheumatoid arthritis focused on autoantibodies and immune complexes. T-cell-mediated antigen-specific responses, T-cell-independent cytokine networks, and aggressive tumour-like behaviour of rheumatoid synovium have also been implicated. More recently, the contribution of autoantibodies has returned to the forefront. Based on the pathogenic mechanisms, specific therapeutic interventions can be designed to suppress synovial inflammation and joint destruction in rheumatoid arthritis.

Corr M, Firestein GS. · Division of Rheumatology, Allergy, and Immunology, University of California, San Diego, School of Medicine, La Jolla, California, USA. · Rheum Dis Clin North Am. · Pubmed #11840699 No free full text.

Abstract: The genetic mechanisms that are complementary in predisposing and then establishing disease are yet to be fully elucidated. During a lifetime, the genetic composition of the host is not only hereditary but undergoes rearrangements, integrations, and more subtle single-base pair alterations. These changes can be inconsequential or lead to aberrant and deleterious pathologic changes. In a complex multifactorial disease such as RA, the relative roles of the dynamic versus germline elements of the disease have yet to be fully determined. Further studies of large populations are likely to segregate out factors affecting specific ethnic, clinical, and genetic subgroups.

Firestein GS, Zvaifler NJ. · Division of Rheumatology, Allergy and Immunology, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0656, USA. · Arthritis Rheum. · Pubmed #11840432 No free full text.

This publication has no abstract.

Yamanishi Y, Firestein GS. · Division of Rheumatology, Allergy, and Immunology, School of Medicine, University of California San Diego, La Jolla, California, USA. · Rheum Dis Clin North Am. · Pubmed #11396097 No free full text.

Abstract: Considering the characteristics of RA synovial tissues such as marked proliferation and invasion to adjacent tissues, comparisons with transformed or neoplastic tissue are natural. RA synovial tissues or cells are not truly malignant, but they have many features of transformation, denoted as "partial transformation" in this article. These features include anchorage-independent growth, loss of contact inhibition, oncogene activation, monoclonal or oligoclonal expansion, detectable telomerase activity, and somatic gene mutations. Although it is not possible to conclude whether most of these cells are permanently changed in association with some genetic alterations or are passively changed by virtue of environmental factors (i.e., cytokine-mediated imprinting), the presence of p53 mutations in RA synovial tissues is especially persuasive. A number of transcription factors play a critical role in the activation, differentiation, and proliferation of RA synovial cells. In particular, the roles of AP-1, MAPKs, and NF-kappa B have been investigated carefully because of their ability to regulate numerous inflammation-related genes. These transcription factors also control expression and activation of matrix-degrading enzymes, including MMPs, aggrecanase, and cysteine proteases, which are the primary enzymes responsible for joint destruction. Elucidation of gene mutations and detailed signal transduction pathways that are specific to RA as well as mechanisms of action of matrix-degrading enzymes may lead to development of a novel therapy for RA. Careful mapping of cytokine networks a decade ago led to groundbreaking advances in therapy. Similarly, methodical evaluation and prioritization of intracellular targets might provide the basis for therapeutic interventions.

Tak PP, Zvaifler NJ, Green DR, Firestein GS. · Division of Clinical Immunology and Rheumatology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands. · Immunol Today. · Pubmed #10652465 No free full text.

Abstract: Oxidative stress at sites of chronic inflammation can cause permanent genetic changes. The development of mutations in the p53 tumor suppressor gene and other key regulatory genes could help convert inflammation into chronic disease in rheumatoid arthritis and other inflammatory disorders.

Kavanaugh A, Rosengren S, Lee SJ, Hammaker D, Firestein GS, Kalunian K, Wei N, Boyle DL. · University of California, San Diego, Division of Rheumatology, Allergy, and Immunology, 9500 Gilman Drive, Mail Code 0943, La Jolla, CA 92093-0943, USA. · Ann Rheum Dis. · Pubmed #17644541 No free full text.

Abstract: OBJECTIVE: Treatment with the anti-CD20 monoclonal antibody (mAb) rituximab is effective in rheumatoid arthritis (RA). Marked depletion of circulating B cells, seen in almost all patients, does not correlate with efficacy. The potential synovial immunomodulatory effects of rituximab have not been fully defined. METHODS: The ARISE trial is an open label, serial synovial biopsy (pre-treatment and 8 weeks) study of rituximab, given 1 g intravenously on days 0 and 14 without peri-infusional steroids, in active RA patients on concomitant methotrexate (MTX). Synovial tissue was analysed by immunohistochemistry with digital image analysis and gene expression by real-time PCR. RESULTS: The mean (SD) baseline DAS28 score was 6.5 (0.4), and mean MTX dose 17.3 mg/week. Of 13 patients, 11 had failed prior tumour necrosis factor (TNF) inhibitor therapy. With treatment, all patients experienced near complete depletion of circulating B cell numbers. During the 6 months after treatment, 7/13 patients achieved an American College of Rheumatology (ACR) 20% improvement (ACR20) response, 3/13 an ACR50 response and 2/13 an ACR70 response. There was a significant decrease in synovial B cells after treatment, but only a small trend towards greater reduction among clinical responders. Among the three patients with ACR50 responses there was a significant decrease in synovial immunoglobulin synthesis. CONCLUSIONS: These data suggest that unlike those in circulation, synovial B cells are decreased but are not eliminated by rituximab therapy. Patients with higher levels of response may have more consistent depletion of synovial B cells, and may also have an alteration in synovial B cell function, as indicated by decreases in synovial immunoglobulin synthesis. Thus, effects on synovial B cells may be necessary but not sufficient for inducing clinical efficacy. Other effects, such as on primary lymph organ B cell antigen presentation or cytokine production, may be operative.

Yoshizawa T, Hammaker D, Boyle DL, Corr M, Flavell R, Davis R, Schett G, Firestein GS. · Division of Rheumatology, Allergy and Immunology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA. · J Immunol. · Pubmed #19561096 No free full text.

Abstract: Development of p38alpha inhibitors for rheumatoid arthritis has been hindered by toxicity and limited efficacy. Therefore, we evaluated whether MKK6, an upstream kinase that regulates multiple p38 isoforms, might be an alternative therapeutic target in inflammatory arthritis. Wild-type (WT), MKK6(-/-), and MKK3(-/-) mice were administered K/BxN serum to induce arthritis. Articular expression of activated kinases and cytokines was determined by Western blot, qPCR, ELISA, and multiplex analysis. Immunoprecipitation and confocal microscopy experiments were performed to determine the subcellular location of MKK6, P-p38, and MAPKAPK2 (MK2). Arthritis scores were significantly lower in MKK6(-/-) mice compared with WT mice. Joint destruction and osteoclast differentiation were lower in MKK6(-/-), as were articular IL-6 and matrix metalloproteinase-3 expression. Phospho-p38 levels were modestly decreased in the joints of arthritic MKK6(-/-) mice compared with WT but were significantly higher than MKK3(-/-) mice. P-MK2 was low in MKK6(-/-) and MKK3(-/-) mice. Uncoupled p38 and MK2 activation was also observed in cultured, MKK6(-/-) FLS and confirmed using kinase assays. Immunoprecipitation assays and confocal microscopy showed that P-p38 and MK2 colocalized in activated WT but not MKK6(-/-) FLS. Distinct patterns of cytokine production were observed in MKK6(-/-) and MKK3(-/-) cells. MKK6 deficiency suppresses inflammatory arthritis and joint destruction, suggesting it might be a therapeutic target for inflammation. Although MKK3 and MKK6 activate the p38 pathway, they regulate distinct subsets of proinflammatory cytokines. MKK6 appears mainly to facilitate p38 and MK2 colocalization in the nucleus rather than to phosphorylate p38.

Offner H, Firestein GS, Boyle DL, Pieters R, Frincke JM, Garsd A, White SK, Reading CL, Auci DL. · Department of Neurology, Oregon Health and Science University, Portland, Oregon, USA. · J Pharmacol Exp Ther. · Pubmed #19297421 No free full text.

Abstract: Dehydroepiandrosterone (DHEA) treatment provides diverse anti-inflammatory benefits in rodent models of diseases, including rheumatoid arthritis (RA), but only limited benefits to patients. In rodents, DHEA is metabolized to (among others) androstene-3beta,7beta,17beta-triol (AET), which retains potent anti-inflammatory activity. 17Alpha-ethynyl-5-androstene-3beta,7beta,17beta-triol (HE3286) is a novel, metabolically stabilized, orally bioavailable derivative of AET. In the DBA mouse model of collagen-induced arthritis (CIA), once-daily oral treatments (gavage) with HE3286 (40 mg/kg), beginning at onset of disease, significantly decreased disease. Benefit was associated with reduction in joint inflammation, erosion, and synovial proliferation as measured by histological analysis and mRNA of proinflammatory cytokines, including tumor necrosis factor-alpha, interleukin (IL)-6, IL-1beta, and IL-23. Significant benefit was also observed in the CIA model even when treatments were delayed until 7 days after the onset of arthritis. Furthermore, dose-dependent benefit was observed in the DBA mouse model of collagen antibody-induced arthritis, as well as reductions in IL-6 and matrix metalloproteinase-3 mRNA levels in joints at the peak of disease and at the end of the study. HE3286, in contrast to dexamethasone, was not immune-suppressive in several classic animal models of immune function. Instead, HE3286 treatment was associated with reduced nuclear factor-kappaB activation and in our previous studies, with increased regulatory T cells. We hypothesize that HE3286 may represent a novel, perhaps first-in-class, anti-inflammatory agent and may more fully translate the benefits of DHEA, heretofore largely limited to rodents, into treatments for human diseases, including autoimmune disorders such as RA.

Sun Y, Mauerhan DR, Firestein GS, Loeffler BJ, Hanley EN, Gruber HE. · Department of Orthopaedic Surgery, Biology Division, Cannon Research 304, Carolinas Medical Center, Charlotte, NC 28232, USA. · J Rheumatol. · Pubmed #19040300 No free full text.

Abstract: OBJECTIVE: To examine the differential gene expression in telomerase transduced osteoarthritis fibroblast-like synoviocytes (hTERT-OA 13A FLS) and telomerase transduced rheumatoid arthritis FLS (hTERT-RA 516 FLS) and test the hypothesis that longterm culture of hTERT-OA 13A FLS display a disease-specific gene expression profile. METHODS: Gene expression in passage 8 hTERT-OA 13A FLS and passage 8 hTERT-RA 516 FLS were compared using microarray assays. Differential expression of selected genes was further examined by reverse transcription-polymerase chain reaction (RT-PCR). After continuous expansion in culture for an additional 4 months, gene expression in the longterm cultures of hTERT-OA 13A FLS and hTERT-RA 516 FLS was again examined with microarray and real-time RT-PCR. RESULTS: hTERT-OA 13A FLS displayed a distinct gene expression profile. While hTERT-RA 516 FLS expressedADAMTS1, ADAMTS3, ADAMTS5, and several carboxypeptidases, hTERT-OA 13A FLS expressed matrix metalloproteinase (MMP)1, MMP3, and several cathepsins at higher levels. Numerous genes classified in the immune response, lipid transport/catabolism, and phosphate transport biological processes were also expressed at higher levels in hTERT-OA 13A FLS. In contrast, numerous genes classified in the positive regulation of cell proliferation, anti-apoptosis, and angiogenesis biological processes were expressed at higher levels in hTERT-RA 516 FLS. Further, of the recently proposed 21 candidate synovial biomarkers of OA, 12 (57%) were detected in our study. CONCLUSION: The findings indicate that OA FLS may not be a passive bystander in OA and that telomerase transduced OA FLS offer an alternative tool for the study of synovial disease markers and for the identification of new therapeutic targets for OA therapy.

Waldburger JM, Boyle DL, Pavlov VA, Tracey KJ, Firestein GS. · University of California, San Diego, La Jolla, CA, USA. · Arthritis Rheum. · Pubmed #18975306 No free full text.

Abstract: OBJECTIVE: The central nervous system can regulate peripheral inflammation, but the efferent neuronal routes and the mediators remain poorly defined. One candidate is the cholinergic pathway, which releases acetylcholine (ACh). This neurotransmitter can bind to the alpha7 cholinergic receptor (alpha7R) expressed by nonneuronal cells and reduce inflammation. To test this possibility, we evaluated the expression of alpha7R and its potential role as a target in rheumatoid arthritis (RA). METHODS: The expression of alpha7R in human synovium and fibroblast-like synoviocytes (FLS) was determined using immunohistochemical, Western blot, and quantitative polymerase chain reaction (PCR) analyses. The effects of ACh in vitro were determined in interleukin-1 (IL-1)-stimulated FLS using immunoassays for protein, quantitative PCR for messenger RNA (mRNA), luciferase reporter constructs for IL-6 and NF-kappaB promoter activity, and electrophoretic mobility shift assays. Expression of alpha7R was knocked down with small interfering RNA (siRNA) or was inhibited with the selective alpha7R antagonist methyllycaconitine (MLA). RESULTS: Protein and mRNA for alpha7R were demonstrated in RA and osteoarthritis synovium and cultured synoviocytes. Expression in synovium was mainly in the intimal lining. ACh significantly reduced the production of IL-6, CXCL8, CCL2, CCL3, CCL5, and granulocyte colony-stimulating factor by IL-1-stimulated FLS. This effect was blocked by the alpha7R antagonist MLA or by using alpha7R siRNA to knock down receptor expression. The selective alpha7R agonist PNU-282,987 decreased the production of IL-6 by IL-1-stimulated FLS. ACh did not reduce IL-6 transcription, but it decreased IL-6 mRNA half-life and reduced IL-6 mRNA steady-state levels. CONCLUSION: The alpha7 receptor is expressed in the synovium and by synoviocytes. Receptor ligation inhibits cytokine expression in FLS through a posttranscriptional mechanism. Therefore, alpha7R is a potential therapeutic target for inflammatory diseases.

Buch MH, Boyle DL, Rosengren S, Saleem B, Reece RJ, Rhodes LA, Radjenovic A, English A, Tang H, Vratsanos G, O'Connor P, Firestein GS, Emery P. · Academic Unit of Musculoskeletal Disease, University of Leeds, Leeds, UK. · Ann Rheum Dis. · Pubmed #18772191 links to  free full text

Abstract: OBJECTIVES: Abatacept is the only agent currently approved to treat rheumatoid arthritis (RA) that targets the co-stimulatory signal required for full T-cell activation. No studies have been conducted on its effect on the synovium, the primary site of pathology. The aim of this study was to determine the synovial effect of abatacept in patients with RA and an inadequate response to tumour necrosis factor alpha (TNFalpha) blocking therapy. METHODS: This first mechanistic study incorporated both dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and arthroscopy-acquired synovial biopsies before and 16 weeks after therapy, providing tissue for immunohistochemistry and quantitative real-time PCR analyses. RESULTS: Sixteen patients (13 women) were studied; all had previously failed TNFalpha-blocking therapy. Fifteen patients completed the study. Synovial biopsies showed a small reduction in cellular content, which was significant only for B cells. The quantitative PCR showed a reduction in expression for most inflammatory genes (Wald statistic of p<0.01 indicating a significant treatment effect), with particular reduction in IFNgamma of -52% (95% CI -73 to -15, p<0.05); this correlated well with MRI improvements. In addition, favourable changes in the osteoprotegerin and receptor activator of nuclear factor kappa B levels were noted. DCE-MRI showed a reduction of 15-40% in MRI parameters. CONCLUSION: These results indicate that abatacept reduces the inflammatory status of the synovium without disrupting cellular homeostasis. The reductions in gene expression influence bone positively and suggest a basis for the recently demonstrated radiological improvements that have been seen with abatacept treatment in patients with RA.

Yoshizawa T, Hammaker D, Sweeney SE, Boyle DL, Firestein GS. · Division of Rheumatology, Allergy and Immunology, University of California, San Diego School of Medicine, La Jolla, CA 92093, USA. · J Immunol. · Pubmed #18713996 No free full text.

Abstract: JNK is a key regulator of matrix metalloproteinase production in rheumatoid arthritis. It is regulated by two upstream kinases known as MKK4 and MKK7. Previous studies demonstrated that only MKK7 is required for cytokine-mediated JNK activation and matrix metalloproteinase expression in cultured fibroblast-like synoviocytes (FLS). However, the functions of MKK4 and MKK7 in synoviocyte innate immune responses have not been determined. TNF, peptidoglycan (PGN), and LPS stimulation led to higher and more prolonged MKK7 phosphorylation compared with MKK4 in FLS. However, this pattern was reversed in poly(I-C) stimulated cells. siRNA knockdown studies showed that TNF, PGN, and LPS-induced JNK and c-Jun phosphorylation are MKK7 dependent, while poly(I-C) responses require both MKK4 and MKK7. Poly(I-C)-induced expression of IP-10, RANTES, and IFN-beta mRNA was decreased in MKK4- or MKK7-deficient FLS. However, MKK4 and MKK7 deficiency did not affect phosphorylation of IkappaB kinase-related kinases in the TLR3 signaling pathway. MKK7, but not MKK4 deficiency, significantly decreased poly(I-C)-mediated IRF3 dimerization, DNA binding, and IFN-sensitive response element-mediated gene transcription. These results were mimicked by the JNK inhibitor SP600125, indicating that JNK can directly phosphorylate IRF3. In contrast, deficiency of either MKK4 or MKK7 decreased AP-1 transcriptional activity. Therefore, JNK is differentially regulated by MKK4 and MKK7 depending on the stimulus. MKK7 is the primary activator of JNK in TNF, LPS, and PGN responses. However, TLR3 requires both MKK4 and MKK7, with the former activating c-Jun and the latter activating both c-Jun and IRF3 through JNK-dependent mechanisms.

Rosengren S, Boyle DL, Firestein GS. · No affiliation provided · Methods Mol Med. · Pubmed #17951672 No free full text.

Abstract: The study of fibroblast-like synoviocytes (FLS) has yielded important insights into the pathogenic mechanisms of rheumatoid arthritis. FLS can be cultured from synovial tissue obtained at joint replacement surgery, synovectomy, or synovial biopsy. After collagenase digestion, adherent cells consist mainly of synovial fibroblasts and synovial macrophages. Proliferating FLS are enriched by repeated passage and comprise >95% of cells by passage 3. Because of cell senescence, use of FLS lines after passage 9 is generally not recommended. FLS in culture have a distinct phenotype with regard to morphology, ultrastructure, surface phenotype, and function. Surface markers that can be used to characterize FLS include positive staining for VCAM-1, CD44, CD55, CD90 (Thy-1), and cadherin-11, coupled with the absence of macrophage markers such as CD14 or CD68.

Kammouni W, Wong K, Ma G, Firestein GS, Gibson SB, El-Gabalawy HS. · University of Manitoba, Winnipeg, Manitoba, Canada. · Arthritis Rheum. · Pubmed #17763440 links to  free full text

Abstract: OBJECTIVE: Rheumatoid arthritis (RA) synovial hyperplasia is related in part to a resistance to apoptosis exhibited by fibroblast-like synoviocytes (FLS). Since hypoxia is a regulator of apoptosis, and since RA synovium is hypoxic, we conducted this study to examine the effects of hypoxia on the Bcl-2 pathway and the role this may play in regulating apoptosis in FLS. METHODS: Synovium samples from RA patients, osteoarthritis (OA) patients, and normal subjects were used for immunohistologic assessments and for generating FLS lines in vitro. FLS were stimulated under conditions of hypoxia (1% O(2)) and using 100 microM CoCl(2) to simulate the effects of severe hypoxia. Changes in the gene expression profile of FLS were evaluated using microarrays and were confirmed by quantitative polymerase chain reaction (PCR). Changes in protein expression were detected by Western blotting. The effect of transient transfection with a BNIP3 plasmid on the apoptosis of FLS was evaluated in the presence and absence of cytokines. RESULTS: Gene expression profiling demonstrated that BNIP3 was unique among the BCL2 family, in that it was induced by hypoxia in FLS. Quantitative PCR indicated a 2-3-fold induction of BNIP3 messenger RNA, and Western blotting showed a 3-5-fold increase in the 30-kd Bcl-2/adenovirus E1B 19-kd protein-interacting protein 3 (BNIP-3) monomer. BNIP-3 was widely expressed in RA synovium and was prominent in FLS from the lining layer. Overexpression of BNIP3 increased FLS apoptosis under hypoxic conditions, an effect that was inhibited by tumor necrosis factor alpha and interleukin-1beta. CONCLUSION: The proapoptotic protein BNIP-3 is induced in FLS by hypoxia and is widely expressed in RA synovium, but its proapoptotic effects may be inhibited in vivo by proinflammatory cytokines. Since overexpression of BNIP3 in FLS increases apoptosis, this may provide a novel approach for controlling synovial hyperplasia in RA.