Rheumatoid Arthritis: Lee DM

Nigrovic PA, Lee DM. · Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA. · Immunol Rev. · Pubmed #17498049 No free full text.

Abstract: Mast cells reside in the normal synovium and increase strikingly in number in rheumatoid arthritis and other joint diseases. Given the broad spectrum of activity of this lineage, it has for decades been considered probable that mast cells are involved in the pathophysiology of synovitis. Recent work in murine arthritis has substantiated this suspicion, showing that mast cells can contribute importantly to the initiation of inflammatory arthritis. However, the role of the greatly expanded population of synovial mast cells in established arthritis remains unknown. Here we review the current understanding of mast cell function in acute arthritis and consider the potentially important influence of this cell on key processes within the chronically inflamed synovium, including leukocyte recruitment and activation, fibroblast proliferation, angiogenesis, matrix remodeling, and injury to collagen and bone. We also consider recent evidence supporting an immunomodulatory or anti-inflammatory role for mast cells as well as pharmacologic approaches to the mast cell as a therapeutic target in inflammatory arthritis.

Nigrovic PA, Lee DM. · Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. · Novartis Found Symp. · Pubmed #16605137 No free full text.

Abstract: A pathogenic role for autoantibodies, immune complexes and mast cells has long been hypothesized in rheumatoid arthritis (RA). Recent studies demonstrating novel RA-associated autoantibodies and the efficacy of B cell-directed therapy have led to a renewed interest in the role of humoral immunity in RA. Mouse models of arthritis have provided further support for a direct pathogenic role of autoantibodies in the development of synovial inflammation. Interestingly, in antibody-mediated K/BxN serum transfer arthritis, mast cells have now been identified as a critical cellular mediator of autoantibody-driven joint inflammation. Here, we focus on the role of autoantibodies and mast cells in murine and human inflammatory arthritis.

Nigrovic PA, Lee DM. · Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts, USA. · Arthritis Res Ther. · Pubmed #15642148 links to  free full text

Abstract: Mast cells are present in limited numbers in normal human synovium, but in rheumatoid arthritis and other inflammatory joint diseases this population can expand to constitute 5% or more of all synovial cells. Recent investigations in a murine model have demonstrated that mast cells can have a critical role in the generation of inflammation within the joint. This finding highlights the results of more than 20 years of research indicating that mast cells are frequent participants in non-allergic immune responses as well as in allergy. Equipped with a diversity of surface receptors and effector capabilities, mast cells are sentinels of the immune system, detecting and delivering a first response to invading bacteria and other insults. Accumulating within inflamed tissues, mast cells produce cytokines and other mediators that may contribute vitally to ongoing inflammation. Here we review some of the non-allergic functions of mast cells and focus on the potential role of these cells in murine and human inflammatory arthritis.

Lee DM, Weinblatt ME. · Division of Rheumatology, Department of Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. · Lancet. · Pubmed #11567728 No free full text.

Abstract: Rheumatoid arthritis is a systemic inflammatory disorder that mainly affects the diarthrodial joint. It is the most common form of inflammatory arthritis, and has a substantial societal effect in terms of cost, disability, and lost productivity. Although the pathogenesis of rheumatoid arthritis remains incompletely understood, much insight into the cellular and molecular mechanisms involved has been gained in the past decade. On the basis of these insights, new therapies have been developed, and clinical trials have shown the efficacy of aggressive treatment of patients with active disease. In this review, we discuss improvements in our understanding of the pathophysiology of inflammatory synovitis in rheumatoid arthritis, and improvements in therapy for patients with the disorder. The past decade has seen substantial advances in these areas. Future studies will be directed at improving methods for early diagnosis and identification of patients with progressive disease, and at improving methods to identify candidates for subclasses of disease-modifying antirheumatic drugs (DMARDs). Long-term safety and efficacy data for the new DMARD agents and combination regimens will also further delineate efficacy and toxicity and thus the appropriate clinical context for use of these therapeutic approaches. The continuing elucidation of pathophysiological pathways relevant in rheumatoid arthritis, coupled with continuing advances in biotechnology and rational drug design, offer substantial hope for the continued development of increasingly potent and specific pharmacotherapy for treatment of rheumatoid arthritis.

Kiener HP, Niederreiter B, Lee DM, Jimenez-Boj E, Smolen JS, Brenner MB. · Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts 02115, USA. · Arthritis Rheum. · Pubmed #19404963 No free full text.

Abstract: OBJECTIVE: To define the expression pattern of cadherin 11 in the destructive pannus tissue of patients with rheumatoid arthritis, and to determine whether cadherin 11 expression in fibroblast-like synoviocytes controls their invasive capacity. METHODS: Cadherin 11 expression in rheumatoid synovial tissue was evaluated using immunohistochemistry. To examine the role of cadherin 11 in regulating the invasive behavior of fibroblast-like synoviocytes, we generated L cell clones expressing wild-type cadherin 11, mutant cadherin 11, and empty vector-transfected controls. The invasive capacity of L cell transfectants and cultured fibroblast-like synoviocytes treated with a blocking cadherin 11-Fc fusion protein or control immunoglobulin was determined in Matrigel invasion assays. RESULTS: Immunohistochemical analysis revealed that cadherin 11 is abundantly expressed in cells at the cartilage-pannus junction in rheumatoid synovitis. Assays to determine invasion demonstrated a 2-fold increased invasive capacity of cadherin 11-transfected L cells compared with L cells transfected with E-cadherin or control vector. The invasive behavior of L cells stably transfected with a cadherin 11 construct that lacked the juxtamembrane cytoplasmic domain was diminished to the level of vector control L cells. Furthermore, treatment with the cadherin 11-Fc fusion protein diminished the invasive capacity of fibroblast-like synoviocytes. CONCLUSION: The results of these in vitro studies implicate a role for cadherin 11 in promoting cell invasion and contribute insight into the invasive nature of fibroblast-like synoviocytes in chronic synovitis and rheumatoid arthritis.

Shin K, Nigrovic PA, Crish J, Boilard E, McNeil HP, Larabee KS, Adachi R, Gurish MF, Gobezie R, Stevens RL, Lee DM. · Department of Medicine, Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. · J Immunol. · Pubmed #19109198 No free full text.

Abstract: Although mast cells (MCs) often are abundant in the synovial tissues of patients with rheumatoid arthritis, the contribution of MCs to joint inflammation and cartilage loss remains poorly understood. MC-restricted tryptase/heparin complexes have proinflammatory activity, and significant amounts of human tryptase beta (hTryptase-beta) are present in rheumatoid arthritis synovial fluid. Mouse MC protease-6 (mMCP-6) is the ortholog of hTryptase-beta, and this serine protease is abundant in the synovium of arthritic mice. We now report that C57BL/6 (B6) mice lacking their tryptase/heparin complexes have attenuated arthritic responses, with mMCP-6 as the dominant tryptase responsible for augmenting neutrophil infiltration in the K/BxN mouse serum-transfer arthritis model. While inflammation in this experimental arthritis model was not dependent on protease-activated receptor-2, it was dependent on the chemokine receptor CXCR2. In support of the latter data, exposure of synovial fibroblasts to hTryptase-beta/heparin or mMCP-6/heparin complexes resulted in expression of the neutrophil chemotactic factors CXCL1/KC, CXCL5/LIX, and CXCL8/IL-8. Our proteomics, histochemistry, and immunohistochemistry data also revealed substantial loss of cartilage-derived aggrecan proteoglycans in the arthritic joints of wild-type B6 mice but not mMCP-6-null B6 mice. These observations demonstrate the functional contribution of MC-restricted tryptase/heparin complexes in the K/BxN mouse arthritis model and connect our mouse findings with rheumatoid arthritis pathophysiology.

McNeil HP, Shin K, Campbell IK, Wicks IP, Adachi R, Lee DM, Stevens RL. · South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia. <> · Arthritis Rheum. · Pubmed #18668540 links to  free full text

Abstract: OBJECTIVE: Increased numbers of mast cells (MCs) that express beta tryptases bound to heparin have been detected in the synovium of patients with rheumatoid arthritis (RA). The corresponding tryptases in mice are mouse MC protease 6 (mMCP-6) and mMCP-7. Although MCs have been implicated in RA and some animal models of arthritis, no direct evidence for a MC-restricted tryptase in the pathogenesis of inflammatory arthritis has been shown. We created transgenic mice that lack heparin and different combinations of mMCP-6 and mMCP-7, to evaluate the roles of MC-restricted tryptase-heparin complexes in an experimental model of arthritis. METHODS: The methylated bovine serum albumin/interleukin-1beta (mBSA/IL-1beta) experimental protocol was used to induce inflammatory monarthritis in different mouse strains. Mice were killed at the time of peak disease on day 7, and histochemical methods were used to assess joint pathology. RESULTS: Arthritis was induced in the knee joints of mBSA/IL-1beta-treated mMCP-6(+)/mMCP-7(-) and mMCP-6(-)/mMCP-7(+) C57BL/6 mice, and numerous activated MCs that had exocytosed the contents of their secretory granules were observed in the diseased mice. In contrast, arthritis was markedly reduced in heparin-deficient mice and in mMCP-6(-)/mMCP-7(-) C57BL/6 mice. CONCLUSION: MC-derived tryptase-heparin complexes play important roles in mBSA/IL-1beta-induced arthritis. Because mMCP-6 and mMCP-7 can compensate for each other in this disease model, the elimination of both tryptases is necessary to reveal the prominent roles of these serine proteases in joint inflammation and destruction. Our data suggest that the inhibition of MC-restricted tryptases could have therapeutic potential in the treatment of RA.

Chen M, Boilard E, Nigrovic PA, Clark P, Xu D, Fitzgerald GA, Audoly LP, Lee DM. · Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. · Arthritis Rheum. · Pubmed #18438856 links to  free full text

Abstract: OBJECTIVE: Prostaglandins (PGs) are found in high levels in the synovial fluid of patients with rheumatoid arthritis, and nonsteroidal blockade of these bioactive lipids plays a role in patient care. The aim of this study was to explore the relative contribution of cyclooxygenase (COX) isoforms and PG species in the autoantibody-driven K/BxN serum-transfer arthritis. METHODS: The prostanoid content of arthritic ankles was assessed in ankle homogenates, and the importance of this pathway was confirmed with pharmacologic blockade. The presence of COX isoforms was assessed by Western blotting and their functional contribution was compared using COX-1-/- and COX-2-/- mice as well as isoform-specific inhibitors. The relative importance of PGE2 and PGI2 (prostacyclin) was determined using mice deficient in microsomal PGE synthase 1 (mPGES-1) and in the receptors for PGI2. RESULTS: High levels of PGE2 and 6-keto-PGF1alpha (a stable metabolite of PGI2) were detected in arthritic joint tissues, correlating strongly with the intensity of synovitis. Pharmacologic inhibition of PG synthesis prevented arthritis and ameliorated active disease. While both COX isoforms were found in inflamed joint tissues, only COX-1 contributed substantially to clinical disease; COX-1-/- mice were fully resistant to disease, whereas COX-2-/- mice remained susceptible. These findings were confirmed by isoform-specific pharmacologic inhibition. Mice lacking mPGES-1 (and therefore PGE2) developed arthritis normally, whereas mice incapable of responding to PGI2 exhibited a significantly attenuated arthritis course, confirming a role of PGI2 in this arthritis model. CONCLUSION: These findings challenge previous paradigms of distinct "housekeeping" versus inflammatory functions of the COX isoforms and highlight the potential pathogenic contribution of prostanoids synthesized via COX-1, in particular PGI2, to inflammatory arthritis.

Hill JA, Bell DA, Brintnell W, Yue D, Wehrli B, Jevnikar AM, Lee DM, Hueber W, Robinson WH, Cairns E. · Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada, N6A 5C1. · J Exp Med. · Pubmed #18391064 links to  free full text

Abstract: Rheumatoid arthritis (RA) is a common autoimmune disease that afflicts the synovium of diarthrodial joints. The pathogenic mechanisms inciting this disease are not fully characterized, but may involve the loss of tolerance to posttranslationally modified (citrullinated) antigens. We have demonstrated that this modification leads to a selective increase in antigenic peptide affinity for major histocompatibility complex (MHC) class II molecules that carry the RA-associated shared epitope, such as HLA-DRB1*0401 (DR4). We describe the induction of arthritis in DR4-IE transgenic (tg) mice with citrullinated fibrinogen, a protein commonly found in inflamed synovial tissue and a frequent target of autoantibodies in RA patients. The disease induced in these mice was characterized by synovial hyperplasia followed by ankylosis, but lacked a conspicuous polymorphonuclear cell infiltrate. Immunological analysis of these mice through T cell epitope scanning and antibody microarray analysis identified a unique profile of citrulline-specific reactivity that was not found in DR4-IE tg mice immunized with unmodified fibrinogen or in wild-type C57BL/6 mice immunized with citrullinated fibrinogen, two conditions where arthritis was not observed. These observations directly implicate citrullinated fibrinogen as arthritogenic in the context of RA-associated MHC class II molecules.

Lee DM, Phillips R, Hagan EM, Chibnik LB, Costenbader KH, Schur PH. · Department of Medicine, Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Smith 552B, 1 Jimmy Fund Way, Boston, Massachusetts 02115, USA. · Ann Rheum Dis. · Pubmed #18390910 No free full text.

Abstract: OBJECTIVE: To determine the significance of quantitative levels of antibodies to cyclic citrullinated peptides (anti-CCP) in a population of patients with rheumatoid arthritis (RA). METHODS: A total of 241 consecutive sera from patients with RA sent from a large rheumatology clinic for laboratory testing were selected for precisely quantifying anti-CCP antibody titres with the anti-CCP2 assay. Patient charts were reviewed for demographic information, smoking history, clinical diagnosis, rheumatoid factor (RF) titre, radiographic information and other laboratory information (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level). Correlations with anti-CCP titre and RF titre, disease parameters and smoking history were assessed. RESULTS: We confirm previous findings that anti-CCP seropositivity is associated with a higher incidence of erosions in patients with RA (56% vs 20% CCP+ vs CCP-, kappa = 0.297, p<0.001). We also found a moderate correlation between anti-CCP titre and RF titre. However, we failed to find an association between anti-CCP titre and presence of erosions, between anti-CCP titre and CRP or ESR level, or between anti-CCP titre and age or disease duration. Interestingly, we did find significantly higher anti-CCP titres in patients with a history of smoking (452 units/ml vs 229 units/ml, smokers vs non-smokers, respectively; p = 0.02). CONCLUSIONS: Although anti-CCP titres were not associated with clinical parameters of disease, they are increased in patients with RA with exposure to tobacco. By contrast, no elevation in RF was noted in patients with a history of smoking. These observations are consistent with a pathogenic contribution of smoking to RA and suggest the immune stimulus for anti-CCP is distinct from that for RF.

Royle L, Campbell MP, Radcliffe CM, White DM, Harvey DJ, Abrahams JL, Kim YG, Henry GW, Shadick NA, Weinblatt ME, Lee DM, Rudd PM, Dwek RA. · Department of Biochemistry, Glycobiology Institute, University of Oxford, Oxford OX1 3QU, UK. · Anal Biochem. · Pubmed #18194658 No free full text.

Abstract: We present a robust, fully automatable technology platform that includes computer software for the detailed analysis of low femtomoles of N-linked sugars released from glycoproteins. Features include (i) sample immobilization in 96-well plates, glycan release, and fluorescent labeling; (ii) quantitative HPLC analysis, including monosaccharide sequence, linkage, and arm-specific information for charged and neutral glycans; (iii) automatic structural assignment of peaks from HPLC profiles via web-based software that accesses our database (GlycoBase) of more than 350 N-glycan structures, including 117 present in the human serum glycome; and (iv) software (autoGU) that progressively analyzes data from exoglycosidase digestions to produce a refined list of final structures. The N-glycans from a plate of 96 samples can be released and purified in 2 or 3 days and profiled in 2 days. This strategy can be used for (i) identification and screening of disease biomarkers and (ii) monitoring the production of therapeutic glycoproteins, allowing optimization of production conditions. This technology is also suitable for preparing released glycans for other analytical techniques. Here we demonstrate its application to rheumatoid arthritis using 5 microl of patient serum.

Plenge RM, Cotsapas C, Davies L, Price AL, de Bakker PI, Maller J, Pe'er I, Burtt NP, Blumenstiel B, DeFelice M, Parkin M, Barry R, Winslow W, Healy C, Graham RR, Neale BM, Izmailova E, Roubenoff R, Parker AN, Glass R, Karlson EW, Maher N, Hafler DA, Lee DM, Seldin MF, Remmers EF, Lee AT, Padyukov L, Alfredsson L, Coblyn J, Weinblatt ME, Gabriel SB, Purcell S, Klareskog L, Gregersen PK, Shadick NA, Daly MJ, Altshuler D. · Program in Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA. · Nat Genet. · Pubmed #17982456 links to  free full text

Abstract: To identify susceptibility alleles associated with rheumatoid arthritis, we genotyped 397 individuals with rheumatoid arthritis for 116,204 SNPs and carried out an association analysis in comparison to publicly available genotype data for 1,211 related individuals from the Framingham Heart Study. After evaluating and adjusting for technical and population biases, we identified a SNP at 6q23 (rs10499194, approximately 150 kb from TNFAIP3 and OLIG3) that was reproducibly associated with rheumatoid arthritis both in the genome-wide association (GWA) scan and in 5,541 additional case-control samples (P = 10(-3), GWA scan; P < 10(-6), replication; P = 10(-9), combined). In a concurrent study, the Wellcome Trust Case Control Consortium (WTCCC) has reported strong association of rheumatoid arthritis susceptibility to a different SNP located 3.8 kb from rs10499194 (rs6920220; P = 5 x 10(-6) in WTCCC). We show that these two SNP associations are statistically independent, are each reproducible in the comparison of our data and WTCCC data, and define risk and protective haplotypes for rheumatoid arthritis at 6q23.

Nigrovic PA, Binstadt BA, Monach PA, Johnsen A, Gurish M, Iwakura Y, Benoist C, Mathis D, Lee DM. · Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA. · Proc Natl Acad Sci U S A. · Pubmed #17277081 links to  free full text

Abstract: Mast cells are immune sentinels that participate in the defense against bacteria and parasites. Resident within the joint, mast cells become activated in human rheumatoid arthritis and are implicated in the pathogenesis of experimental murine synovitis. However, their arthritogenic role remains undefined. Using a model of autoantibody-induced arthritis, we show that mast cells contribute to the initiation of inflammation within the joint by elaboration of IL-1. Mast cells become activated to produce this cytokine via the IgG immune complex receptor FcgammaRIII. Interestingly, mast cells become dispensable for the perpetuation of arthritis after delivery of IL-1, highlighting the contribution of this lineage to arthritis induction. These findings illuminate a mechanism by which mast cells can participate in the pathogenesis of autoimmune inflammatory arthritis and provide insights of potential relevance to human rheumatoid arthritis.

Lee DM, Kiener HP, Agarwal SK, Noss EH, Watts GF, Chisaka O, Takeichi M, Brenner MB. · Department of Medicine and Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115, USA. · Science. · Pubmed #17255475 links to  free full text

Abstract: The normal synovium forms a membrane at the edges of joints and provides lubrication and nutrients for the cartilage. In rheumatoid arthritis, the synovium is the site of inflammation, and it participates in an organized tissue response that damages cartilage and bone. We identified cadherin-11 as essential for the development of the synovium. Cadherin-11-deficient mice have a hypoplastic synovial lining, display a disorganized synovial reaction to inflammation, and are resistant to inflammatory arthritis. Cadherin-11 therapeutics prevent and reduce arthritis in mouse models. Thus, synovial cadherin-11 determines the behavior of synovial cells in their proinflammatory and destructive tissue response in inflammatory arthritis.

Paniagua RT, Sharpe O, Ho PP, Chan SM, Chang A, Higgins JP, Tomooka BH, Thomas FM, Song JJ, Goodman SB, Lee DM, Genovese MC, Utz PJ, Steinman L, Robinson WH. · Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, California, USA. · J Clin Invest. · Pubmed #16981009 links to  free full text

Abstract: Tyrosine kinases play a central role in the activation of signal transduction pathways and cellular responses that mediate the pathogenesis of rheumatoid arthritis. Imatinib mesylate (imatinib) is a tyrosine kinase inhibitor developed to treat Bcr/Abl-expressing leukemias and subsequently found to treat c-Kit-expressing gastrointestinal stromal tumors. We demonstrate that imatinib potently prevents and treats murine collagen-induced arthritis (CIA). We further show that micromolar concentrations of imatinib abrogate multiple signal transduction pathways implicated in RA pathogenesis, including mast cell c-Kit signaling and TNF-alpha release, macrophage c-Fms activation and cytokine production, and fibroblast PDGFR signaling and proliferation. In our studies, imatinib attenuated PDGFR signaling in fibroblast-like synoviocytes (FLSs) and TNF-alpha production in synovial fluid mononuclear cells (SFMCs) derived from human RA patients. Imatinib-mediated inhibition of a spectrum of signal transduction pathways and the downstream pathogenic cellular responses may provide a powerful approach to treat RA and other inflammatory diseases.

Kiener HP, Lee DM, Agarwal SK, Brenner MB. · Brigham and Women's Hospital and the Department of Medicine, Division of Rheumatology, Immunology, and Allergy, Harvard Medical School, Boston, Massachusetts 02115, USA. · Am J Pathol. · Pubmed #16651616 links to  free full text

Abstract: The synovial lining of diarthrodial joints is composed of a condensed network of synoviocytes that form an intact layer via cell-to-cell contacts with significant intercellular matrix spaces. However, the molecular basis for synovial lining formation and its structural integrity has not been previously defined. In this study, using a three-dimensional fibroblast-like synoviocyte in vitro organ culture system, we provide evidence that cadherin-11 expressed in fibroblast-like synoviocytes plays a determining role in establishing the synovial lining layer. Fibroblast-like synoviocytes that were grown in three-dimensional matrices demonstrated formation of a lining structure at the interface between the matrix and the fluid phase. Treatment of fibroblast-like synoviocyte organ cultures with a cadherin-11-Fc fusion protein efficiently abrogated lining layer organization. Moreover, because E-cadherin-expressing fibroblasts failed to organize a lining layer structure at the tissue boundary, this effect appears to be a distinct characteristic of fibroblasts expressing cadherin-11. We found that cadherin-11 mediated fibroblast-like synoviocyte cell-to-cell adhesion via formation of adherens junctions that were linked to and remodeled the actin cytoskeleton. Together, these studies implicate cadherin-11 in synovial tissue and lining layer formation and provide an in vitro system to model fibroblast-like synoviocyte behavior and function in organizing the synovial tissue.

Chen M, Lam BK, Kanaoka Y, Nigrovic PA, Audoly LP, Austen KF, Lee DM. · Department of Medicine and Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. · J Exp Med. · Pubmed #16567388 links to  free full text

Abstract: Neutrophils serve as a vanguard of the acute innate immune response to invading pathogens. Neutrophils are also abundant at sites of autoimmune inflammation, such as the rheumatoid joint, although their pathophysiologic role is incompletely defined and relevant effector functions remain obscure. Using genetic and pharmacologic approaches in the K/BxN serum transfer model of arthritis, we find that autoantibody-driven erosive synovitis is critically reliant on the generation of leukotrienes, and more specifically on leukotriene B4 (LTB4), for disease induction as well as perpetuation. Pursuing the cellular source for this mediator, we find via reconstitution experiments that mast cells are a dispensable source of leukotrienes, whereas arthritis susceptibility can be restored to leukotriene-deficient mice by intravenous administration of wild-type neutrophils. These experiments demonstrate a nonredundant role for LTB4 in inflammatory arthritis and define a neutrophil mediator involved in orchestrating the synovial eruption.

Valencia X, Higgins JM, Kiener HP, Lee DM, Podrebarac TA, Dascher CC, Watts GF, Mizoguchi E, Simmons B, Patel DD, Bhan AK, Brenner MB. · Dept. of Medicine, Div. of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Smith Bldg., Rm. 552, One Jimmy Fund Way, Boston, MA 02115, USA. · J Exp Med. · Pubmed #15611293 links to  free full text

Abstract: Cadherins are integral membrane proteins expressed in tissue-restricted patterns that mediate homophilic intercellular adhesion. During development, they orchestrate tissue morphogenesis and, in the adult, they determine tissue integrity and architecture. The synovial lining is a condensation of fibroblast-like synoviocytes (FLS) and macrophages one to three cells thick. These cells are embedded within the extracellular matrix, but the structure is neither an epithelium nor an endothelium. Previously, the basis for organization of the synovium into a tissue was unknown. Here, we cloned cadherin-11 from human rheumatoid arthritis (RA)-derived FLS. We developed L cell transfectants expressing cadherin-11, cadherin-11 fusion proteins, and anti-cadherin-11 mAb. Cadherin-11 was found to be expressed mainly in the synovial lining by immunohistologic staining of human synovium. FLS adhered to cadherin-11-Fc, and transfection of cadherin-11 conferred the formation of tissue-like sheets and lining-like structures upon fibroblasts in vitro. These findings support a key role for cadherin-11 in the specific adhesion of FLS and in synovial tissue organization and behavior in health and RA.

Lee DM, Schur PH. · Department of Medicine, Division of Rheumatology, Immunology and Allergy Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. · Ann Rheum Dis. · Pubmed #12922961 links to  free full text

Abstract: OBJECTIVES: To determine the frequency of antibodies to cyclic citrullinated peptides (CCP) in a group of patients with a diversity of rheumatic diseases. METHODS: 249 consecutive sera from an arthritis clinic sent for rheumatology testing were selected for testing with the anti-CCP2 assays and for the presence of rheumatoid factor (RF). Patient charts were reviewed for demographic information, clinical diagnosis, radiographic information, and other laboratory data. RESULTS: The sensitivity and specificity of anti-CCP reactivity for the diagnosis of rheumatoid arthritis (RA) were 66.0% and 90.4%, respectively. This compared with the sensitivity and specificity of RF for RA at 71.6% and 80.3%. Furthermore, 10/29 (34%) RF- patients with RA demonstrated reactivity to CCP. The presence of either anti-CCP or RF increased testing sensitivity for diagnosis of RA to 81.4%; the presence of both RF and anti-CCP demonstrated a testing specificity similar to that of anti-CCP reactivity alone for the diagnosis of RA (91.1%). CONCLUSIONS: The detection of anti-CCP is useful for the diagnosis of RA, in fact even more so than RF, because of its higher specificity.

Matsumoto I, Lee DM, Goldbach-Mansky R, Sumida T, Hitchon CA, Schur PH, Anderson RJ, Coblyn JS, Weinblatt ME, Brenner M, Duclos B, Pasquali JL, El-Gabalawy H, Mathis D, Benoist C. · Joslin Diabetes Center and Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215, USA. · Arthritis Rheum. · Pubmed #12687536 links to  free full text

Abstract: OBJECTIVE: Arthritis in the K/BxN mouse model results from pathogenic immunoglobulins that recognize glucose-6-phosphate isomerase (GPI), a glycolytic enzyme residing in the cytoplasm of all cells. Antibodies directed against GPI can, alone, transfer arthritis to healthy recipients. Previous experiments have revealed significant titers of anti-GPI antibodies in the serum of many patients with rheumatoid arthritis (RA). We evaluated the generality of these observations in cohorts of patients with 12 different arthritic and chronic autoimmune diseases and in population-matched healthy control subjects. METHODS: Anti-GPI antibodies were assayed in 811 individual serum samples by enzyme-linked immunosorbent assay with 2 forms of GPI, recombinant and native. Results were confirmed by immunoblotting. RESULTS: Several patients had significantly elevated anti-GPI antibody titers, but without the prevalence or the specificity reported previously. Only 15% of RA patients had anti-GPI antibodies (range 12-29% in different cohorts), with a higher prevalence in patients with active disease. Psoriatic arthritis, undifferentiated arthritis, and spondylarthropathy patients also displayed anti-GPI antibodies at similar frequencies (12-25%). Similar titers were detected in a proportion (5-10%) of control subjects or patients with Crohn's disease or sarcoidosis. Very high titers were found in rare cases of RA and systemic lupus erythematosus. CONCLUSION: No disease-specific pattern of antibody positivity to GPI was apparent. While the antibody-mediated mechanism at play in the mouse model may exemplify a generic mechanism for some forms of arthritis in humans, GPI itself does not appear to be a target common to the majority of RA patients.

Matsumoto I, Maccioni M, Lee DM, Maurice M, Simmons B, Brenner M, Mathis D, Benoist C. · Section on Immunology and Immunogenetics, Joslin Diabetes Center; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 1 Joslin Place, Boston, MA 02115, USA. · Nat Immunol. · Pubmed #11896391 No free full text.

Abstract: Arthritis in the K/BxN mouse model results from pathogenic immunoglobulins (Igs) that recognize the ubiquitous cytoplasmic enzyme glucose-6-phosphate isomerase (GPI). But how is a joint-specific disease of autoimmune and inflammatory nature induced by systemic self-reactivity? No unusual amounts or sequence, splice or modification variants of GPI expression were found in joints. Instead, immunohistological examination revealed the accumulation of extracellular GPI on the lining of the normal articular cavity, most visibly along the cartilage surface. In arthritic mice, these GPI deposits were amplified and localized with IgG and C3 complement. Similar deposits were found in human arthritic joints. We propose that GPI-anti-GPI complexes on articular surfaces initiate an inflammatory cascade via the alternative complement pathway, which is unbridled because the cartilage surface lacks the usual cellular inhibitors. This may constitute a generic scenario of arthritogenesis, in which extra-articular proteins coat the cartilage or joint extracellular matrix.

Ji H, Ohmura K, Mahmood U, Lee DM, Hofhuis FM, Boackle SA, Takahashi K, Holers VM, Walport M, Gerard C, Ezekowitz A, Carroll MC, Brenner M, Weissleder R, Verbeek JS, Duchatelle V, Degott C, Benoist C, Mathis D. · Section on Immunology and Immunogenetics, Joslin Diabetes Center, Boston, MA 02215, USA. · Immunity. · Pubmed #11869678 No free full text.

Abstract: K/BxN T cell receptor transgenic mice are a model of inflammatory arthritis, similar to rheumatoid arthritis. Disease in these animals is focused specifically on the joints but stems from autoreactivity to a ubiquitously expressed antigen, glucose-6-phosphate isomerase (GPI). T and B cells are both required for disease initiation, but anti-GPI immunoglobulins (Igs), alone, can induce arthritis in lymphocyte-deficient recipients. Here, we show that the arthritogenic Igs act through both Fc receptors (in particular, FcgammaRIII) and the complement network (C5a). Surprisingly, the alternative pathway of complement activation is critical, while classical pathway components are entirely dispensable. We suggest that autoimmune disease, even one that is organ specific, can occur when mobilization of an adaptive immune response results in runaway activation of the innate response.