Pathogenesis Of Joint Destruction Research Articles

Protective Role of Optineurin Against Joint Destruction in Rheumatoid Arthritis Synovial Fibroblasts

Optineurin (OPTN) is an autophagy adaptor/receptor that acts as an intrinsic negative regulator of osteoclast differentiation. RANKL expressed by rheumatoid arthritis synovial fibroblasts (RASFs) is primarily responsible for the development of bone erosions in patients with RA. The aim of the present study was to explore the role of OPTN in the pathogenesis of joint destruction in RA. RASFs were left untreated or incubated with tumor necrosis factor (TNF) or interferon-γ (IFNγ), and expression of OPTN by RASFs was analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Expression of RANKL and osteoprotegerin (OPG) was evaluated in cultures of OPTN-reduced RASFs with or without TNF or IFNγ treatment. OPTN-reduced RASFs were cocultured with monocytes and stained for tartrate-resistant acid phosphatase (TRAP). IκBα, NF-κB1, and RelA protein levels were measured to evaluate NF-κB signaling. Expression of messenger RNA (mRNA) for matrix metalloproteinase 3 (MMP3), interleukin-6 (IL6), GATA binding protein 3 (GATA3), carbohydrate sulfotransferase 15 (CHST15), hyaluronan synthase 1 (HAS1), and GATA1 was analyzed by RT-qPCR. In RASFs incubated with TNF or IFNγ, OPTN expression was up-regulated and RANKL expression was increased, and these effects were further pronounced in OPTN-reduced RASFs (all P < 0.05 versus controls). OPG mRNA levels remained unchanged. Monocytes cocultured with OPTN-reduced RASFs differentiated to a greater extent into TRAP+ multinucleated cells compared to monocytes cocultured with control RASFs (P < 0.05). IκBα degradation and nuclear NF-κB1 expression following TNF treatment were both prolonged in OPTN-reduced RASFs (each P < 0.05 versus controls). MMP3 mRNA levels were up-regulated, while GATA3, CHST15, and HAS1 mRNA levels were down-regulated in OPTN-reduced RASFs (each P < 0.05 versus controls). OPTN plays a protective role in RA when it is up-regulated in RASFs in the presence of proinflammatory cytokines. Absence of OPTN might worsen RA by generating a joint-destructive state, as indicated by evidence of increased RANKL expression on RASFs and subsequent osteoclast differentiation.

Systematic Analysis of Differential Expression Profile in Rheumatoid Arthritis Chondrocytes Using Next-Generation Sequencing and Bioinformatics Approaches.

Cartilage destruction in rheumatoid arthritis (RA) occurs primarily in the pannus-cartilage interface. The close contact of the synovium-cartilage interface implicates crosstalk between synovial fibroblasts and chondrocytes. The aim of this study is to explore the differentially expressed genes and novel microRNA regulations potentially implicated in the dysregulated cartilage homeostasis in joint destruction of RA. Total RNAs were extracted from human primary cultured normal and RA chondrocytes for RNA and small RNA expression profiling using next-generation sequencing. Using systematic bioinformatics analyses, we identified 463 differentially expressed genes in RA chondrocytes were enriched in biological functions related to altered cell cycle process, inflammatory response and hypoxic stimulation. Moreover, fibroblast growth factor 9 (FGF9), kynureninase (KYNU), and regulator of cell cycle (RGCC) were among the top dysregulated genes identified to be potentially affected in the RA joint microenvironment, having similar expression patterns observed in arrays of clinical RA synovial tissues from the Gene Expression Omnibus database. Additionally, among the 31 differentially expressed microRNAs and 10 candidate genes with potential microRNA-mRNA interactions in RA chondrocytes, the novel miR-140-3p-FGF9 interaction was validated in different microRNA prediction databases, and proposed to participate in the pathogenesis of joint destruction through dysregulated cell growth in RA. The findings provide new perspectives for target genes in the management of cartilage destruction in RA.

Role of LIGHT in the pathogenesis of joint destruction in rheumatoid arthritis.

AIMTo characterise the role of substitutes for receptor-activator nuclear factor kappa-B ligand (RANKL) in rheumatoid arthritis (RA) joint destruction.METHODSSynovial fluid (SF) macrophages isolated from the knee joint of RA patients were incubated with 25 ng/mL macrophage-colony stimulating factor (M-CSF) and 50 ng/mL LIGHT (lymphotoxin-like, exhibits inducible expression and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes) in the presence and absence of 25 ng/mL RANKL and 100 ng/mL osteoprotegerin (OPG) on glass coverslips and dentine slices. Osteoclastogenesis was assessed by the formation of multinucleated cells (MNCs) expressing tartrate-resistant acid phosphatase (TRAP) on coverslips and the extent of lacunar resorption pit formation on dentine slices. The concentration of LIGHT in RA and osteoarthritis (OA) synovial fluid was measured by an enzyme-linked immunosorbent assay (ELISA) and the expression of LIGHT in RA and OA synovium was determined by immunohistochemistry using an indirect immunoperoxidase technique.RESULTSIn cultures of RA SF macrophages treated with LIGHT and M-CSF, there was significant formation of TRAP + MNCs on coverslips and extensive lacunar resorption pit formation on dentine slices. SF-macrophage-osteoclast differentiation was not inhibited by the addition of OPG, a decoy receptor for RANKL. Resorption pits were smaller and less confluent than in RANKL-treated cultures but the overall percentage area of the dentine slice resorbed was comparable in LIGHT- and RANKL-treated cultures. LIGHT significantly stimulated RANKL-induced lacunar resorption compared with RA SF macrophages treated with either RANKL or LIGHT alone. LIGHT was strongly expressed by synovial lining cells, subintimal macrophages and endothelial cells in RA synovium and the concentration of LIGHT was much higher in RA compared with OA SF.CONCLUSIONLIGHT is highly expressed in RA synovium and SF, stimulates RANKL-independent/dependent osteoclastogenesis from SF macrophages and may contribute to marginal erosion formation.

THU0039 B1-Integrin is a Critical Mediator of TLR2-Induced Migrational and Invasive Mechanisms in RA Synovial Fibroblast Cells

BackgroundRheumatoid arthritis (RA) is a chronic, progressive autoimmune disease, characterized by synovial proliferation and destruction of cartilage and bone. Engagement of integrin receptors induces cell migration/invasion through attachment to the...

Synovial Infiltration with CD79a-positive B Cells, But Not Other B Cell Lineage Markers, Correlates with Joint Destruction in Rheumatoid Arthritis

The efficacy of B cell depletion in the treatment of patients with rheumatoid arthritis (RA) has revitalized interest in the pathogenic role(s) of B cells in RA. We evaluated the distribution of synovial B lineage cells and their correlation with histologic disease activity and joint destruction in RA. Synovial tissue samples were obtained by closed-needle biopsy from 69 Chinese patients with active RA, from 14 patients with osteoarthritis (OA), and from 15 with orthopedic arthropathies (OrthA) as disease controls. Serial tissue sections were stained immunohistochemically for CD79a (pro-B cell to plasma cell), CD20 (B cells), CD38 (plasma cells), CD21 (follicular dendritic cells), CD68 (macrophages), CD3 (T cells), and CD34 (endothelial cells). Densities of positive-staining cells were determined and correlated with histologic disease activity (Krenn 3-component synovitis score) and radiographic joint destruction (Sharp score). Mean sublining CD79a-positive cell density was significantly higher in RA than in OA (p <0.001) or OrthA (p = 0.003). Receiver operating characteristic curve analysis showed that CD79a-positive cell density differentiated RA well from OA [area under the curve (AUC) = 0.79] or OrthA (AUC = 0.75). Spearman's rank order correlation showed significant correlations between sublining CD79a-positive cell density and the synovitis score (r = 0.714, p < 0.001), total Sharp score (r = 0.490, p < 0.001), and the erosion subscore (r = 0.545, p < 0.001), as well as the joint space narrowing subscore (r = 0.468, p = 0.001) in RA. Synovial CD79a-positive B cells may be a helpful biomarker for histologic disease activity in RA and may be involved in the pathogenesis of joint destruction in RA.

Pathogenesis of Joint Destruction in Rheumatoid Arthritis

Synovial mesenchymal cells, matrix metalloproteinases (MMPs), and osteoclasts are the three major players directly responsible for the pathogenesis of rheumatoid joint destruction. First, synovial mesenchymal cells, internally driven by a transcription factor c-Fos/AP-1, not only directly invade cartilage and bone as a granulation tissue called "pannus" but also release inflammatory cytokine interleukin (IL)-1β. IL-1β induces MMPs and activates osteoclasts. Synovial cells can also present antigen to T cells to drive antigen-specific immune responses. Second, cartilaginous joint matrix can only be degraded after the first attack of collagen fibrils by MMPs, and importantly, most of the MMPs are under the control of c-Fos/AP-1 and IL-1β as well. Third, differentiation of osteoclast is driven internally by NFATc1, where NFATc1 is under the control of TRAF6, c-Fos/AP-1 and osteoclastogenic signaling complex. IL-1β has been shown to induce osteoclastogenesis directly and also indirectly via signaling through RANKL. Therefore, IL-1β and c-Fos/AP-1 influence each other's gene expression and activity, resulting in an orchestrated cross-talk that is crucial to arthritic joint destruction, and thus, blockade of IL-1β and/or c-Fos/AP-1 can be most promising as a therapeutic target, and in fact, a selective inhibition of c-Fos/AP-1 does resolve arthritic joint destruction.

Molecular Targets of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a multifactorial disease characterized by chronic inflammation of the joints. Both genetic and environmental factors are involved in the pathogenesis of joint destruction and disability. In the inflamed RA joint, the synovium is highly infiltrated by CD4+ T cells, B cells, and macrophages. Furthermore, the intimal lining becomes hyperplastic due to the increased numbers of macrophage-like and fibroblast-like synoviocytes. This hyperplastic intimal synovial lining forms an aggressive front, called pannus, which invades cartilage and bone structures, leading to compromised function and/or destruction of affected joints. RA pathology is mediated by a number of cytokines (TNF-alpha, IL-1, IL-6, IL-17, IFN gamma, etc.), chemokines (MCP-1, MCP-4, CCL18, etc.), cell adhesion molecules (ICAM-1, VCAM-1, etc.) and matrix metalloproteinases. Currently, treatment strategies targeted against TNF-alpha, IL-1 and IL-6 are available. In this review, we will summarize the use of biologics, the pros and cons of the use of biologics, and discuss on the potential molecular targets of RA.

Traditional and Newer Therapeutic Options for Psoriatic Arthritis

Psoriatic arthritis (PsA) is a destructive form of inflammatory arthritis that occurs in about one-third of patients with psoriasis. The pathogenesis of PsA includes genetic and immunological factors. A review of the currently available therapies reveals that traditional disease-modifying medications have provided only marginal relief from joint inflammation in patients with PsA, and have not been successful in controlling the disease and preventing joint damage. On the basis of current understanding of the pathogenesis of joint destruction in PsA, several new medications have been introduced, including anti-tumour necrosis factor (TNF) agents and agents that interfere with T-cell function. Most of these medications have been found to be effective in both psoriasis and PsA. Recent randomised controlled trials suggest that at least anti-TNF agents may help prevent progression of joint destruction.

Markers in rheumatoid arthritis

Proteinases play an important role in the pathogenesis of joint destruction, and matrix metalloproteinases (MMP) are believed to play a crucial role as they have the ability to degrade various compounds of the extra-cellular matrix of the joints, including collagen. The work described in this presentation focuses on the question of which MMPs and in what forms are they present in synovial fluid (SF) and the circulation of patients with joint pathology. Also, the applicability of the MMP measurements as markers of disease activity or joint damage progression is investigated. High levels of proMMP-3, proMMP-8 and proMMP-9 were found in SF and in the circulation of the rheumatoid arthritis (RA) patients as compared with the control population or osteoarthritis patients. Also MMP activity in MMP/α2-macroglobulin (α2M) complexes was shown to be higher in RA patients. Moreover, it was shown that proMMP-8 and proMMP-9 (collagenase 2 and gelatinase B) levels are related to the levels of collagen degradation products (hydroxyproline) in SF. Although there is only a trend towards correlation between proMMP-8 and hydroxyproline in SF, levels of proMMP-3 were not correlated with hydroxyproline levels. Comparison between systemic levels of inflammation (C-reactive protein) and MMP levels showed the opposite situation. Only proMMP-3 levels were correlated with C-reactive protein, and not proMMP-8 or proMMP-9 levels. These observations suggested that the aforementioned enzymes can be seen as candidate markers for the pathophysiological processes of joint inflammation and degradation. Moreover, MMP activity in MMP/α2M complexes was considered a possible marker of the proteolytic system since increased levels of MMP activity were found in SF and in the serum of RA patients as compared with osteoarthritis patients. To investigate the predictive role of MMP levels in the circulation, we measured MMPs in patients in an Early Arthritis Clinic. The results show that proMMP-3 levels at the onset of the disease were predictive of cartilage loss at the end of the second year of the follow-up period. Moreover, proMMP-3 predicted joint damage progression independently from other known parameters such as sheared epitope or rheumatoid factor. Collagenase-2 (MMP-8) was not predictive of joint damage, and neither were high levels of proMMP-9. Based on these findings, we conclude that whereas MMP-8 and MMP-9 levels reflect the current status of the protheolytic system, MMP-3 levels at the onset of RA show the potential of the system to be destructive. It is extensively documented that protein levels of tissue inhibitor of metalloproteinase (TIMP)-1 in SF and in the circulation of RA patients are insufficient to counteract the increased production of MMPs. However, little is known about the activation of proMMPs in vivo. It was previously indicated that activated, but not TIMP-inhibited, MMPs can be neutralized by α2M. We hypotheized that in pathological situations involving joint inflammation and destruction the high production of proMMPs leads to increased levels of activated MMPs, and because of the MMP/TIMP imbalance high levels of MMP/α2M complexes may be found in these conditions. Thus, high levels of MMP/α2M complexes would support the idea of a MMP/TIMP imbalance. To test this hypothesis, a method to measure MMP activity in MMP/α2M complexes using small fluorogenic substrates, such as TNO211-F, was developed. Indeed, high levels of MMP in complexes with α2M are found in SF and in the circulation of patients with joint pathology. The presence of increased levels of α2M/MMP complexes shows that TIMP levels are insufficient to inhibit all activated MMPs; thus, the MMP/TIMP imbalance theory is supported by these findings. In conclusion, the results to be discussed show that high proMMP production leads to increased levels of activated MMP in SF and the systemic circulation of RA patients. Upon activation MMPs form complexes with α2M in SF and in the systemic circulation of RA patients, which is at least partly responsible for neutralization of MMPs. MMP-1, MMP-3, MMP-8 and MMP-9 are likely to be involved the pathogenesis of RA as shown by the MMP profile in SF and the serum of RA patients. proMMP-3 levels at the onset of RA are predictive of the progression of joint damage. The MMP/TIMP imbalance is present in various joint pathologies. MMP/α2M complexes are reduced in the systemic circulation of RA patients upon treatment with disease-modifying anti-rheumatic drugs.

Treatment of psoriatic arthritis with etanercept

The secretion of proinflammatory cytokines such as tumor necrosis factor α (TNF-α) is believed to play a critical role in the pathogenesis of joint destruction in rheumatoid arthritis.1Feldman M Brennan FM Maini RM. The role of cytokines in rheumatoid arthritis.Annu Rev Immunol. 1996; 14: 397-403Crossref PubMed Scopus (2286) Google Scholar The dimeric fusion protein etanercept (Enbrel), consisting of the 75-kd TNF-α receptor linked to the Fc portion of human IgG1 has been successfully used to antagonize the persistent inflammatory stimulation due to TNF-α.2Moreland LW Baumgartner SW Schiff MH Tindall EA Fleischmann RM Weaver AL et al.Treatment of rheumatoid arthritis with a recombinant human tumor necrosis factor receptor (p75)-Fc fusion protein.N Engl J Med. 1997; 337: 141-147Crossref PubMed Scopus (1506) Google Scholar Because psoriatic arthritis in many ways resembles rheumatoid arthritis, we decided to treat a patient suffering from mutilating and extremely painful psoriatic arthritis with etanercept because of contraindications to standard therapeutic procedures such as methotrexate or cyclosporine. At presentation in our clinic in November 1999, the 50-year-old male patient was dependent on a wheelchair and a daily intake of high doses of analgesic medication, including nonsteroidal anti-inflammatory drugs and morphine. Etanercept was given at a dose of 25 mg subcutaneously twice a week, and no systemic or local side effects were observed. Four weeks after initiation of therapy an initial increase in mobility and a decrease in articular pain were noticed, leading to a reduced need for analgesic medication. The clinical improvement was accompanied by a normalization of serologic signs of inflammation, and C-reactive protein returned to normal levels during therapy. Three months after initiation of etanercept therapy, the patient was able to walk distances of up to 50 m without using the wheelchair, and the swelling and pain of the joints had decreased dramatically. Skin involvement of the disease was not significantly altered by etanercept therapy. To our knowledge, this is the first report on the use of etanercept in the treatment of psoriasis-related arthritis. According to available information etanercept has no significant organ toxicity, which makes this substance an interesting alternative for therapy in patients with contraindications to other substances commonly used for the treatment of psoriatic arthritis. Furthermore, the combination of etanercept and methotrexate has been shown to be of great efficiency in patients with rheumatoid arthritis and might be similarly effective in patients with severe psoriasis.3Weinblatt ME Kremer JM Bankhurst AD Bulpitt KJ Fleischmann RM Fox RI et al.A trial of etanercept, a recombinant tumor necrosis factor: Fc fusion protein, in patients with rheumatoid arthritis receiving methotrexate.N Engl J Med. 1999; 340: 253-259Crossref PubMed Scopus (1925) Google Scholar Taken together, the use of cytokine-antagonizing substances such as etanercept provides a promising approach in the treatment of psoriatic arthritis. Controlled randomized studies are needed to further determine the value of this substance, administered either alone or in combination with other immunosuppressive medication. Addendum: While this letter was in press, Mease et al reported a randomized trial on the successful use of etanercept therapy for psoriatic arthritis (Lancet 2000;356:385-90).

Fibroblast biology: Synovial fibroblasts in rheumatoid arthritis - leading role or chorus line?

The continuing saga of the aetiology and pathogenesis of joint destruction in rheumatoid arthritis (RA) has often led to reassessment of the working hypotheses created to explain the phenomenon. Initial and current models set a protagonistic role for inflammatory and autoimmune cellular mediators in RA, and this notion has been well supported by a plethora of experimental data. However, it may have been biased by the relatively more easy access to experimental and clinical data regarding immune cell function and also, perhaps, by the overenthusiasm with which it was felt cellular immunology could explain chronic immunopathologies. Even from early investigations, however, it has been clear that for arthritis development, inflammatory and autoimmune processes actively interacted with a network of non-immune cell types, and that it was the effector activities of these cell types that resulted in cartilage and bone attack. Although, until recently, the non-immune constituents of the synovial lining were regarded as mere targets of the inflammatory milieu and as secondary players in the development of disease, more recent data provide serious grounds for considering these cells as dominant players in the aetiopathogenesis of RA. The series of reviews on synovial fibroblasts (SFs) presented in this issue of Arthritis Research aims to refocus attention on our current knowledge of the biology of SFs and their possible involvement in the development of RA.

Selection of Self-reactive Peptides Within Human Aggrecan by use of a HLA-DRB1*0401 Peptide Binding Motif

The pathogenesis of joint destruction in rheumatoid arthritis remains ill-defined. Joint destruction is thought to be the result of tissue damage mediated by T cells. The mere presence of articular cartilage appears responsible for sustaining chronic synovitis and thereby forwards a role for cartilage-responsive T cells in RA. Taking advantage of the positive DRB1*0401 association with RA susceptibility, we reasoned that T-cell recognition of autoantigens in RA would be restricted by DRB1*0401-encoded molecules. A DR4 (B1*0401) peptide binding motif was used for the identification of putative T-cell epitopes within human aggrecan, a candidate autoantigen. Thirteen peptides were synthesized and tested for binding DRB1*0401 or 0404-encoded molecules. Selected binders were tested for induction of pro-liferative responses in peripheral blood mononuclear cells from donors carrying the DR4 or DR1 specificity. Both healthy and RA donors responded to human aggrecan-derived peptides, thereby identifying these sequences as T-cell epitopes. Interestingly, responses to aggrecan-derived epitopes were significantly decreased in RA patients compared to controls. This was not due to an overall hyporesponsiveness of RA patients since responses to a recall antigen or mitogen did not differ from controls. The data suggest that in RA, aggrecan-specific T cells may exist in a different stage of activation or may have left the periphery to home to the joint.

The pathogenesis of joint destruction in chronic polyarthritis

Joint destruction, a hallmark of rheumatoid arthritis, is described with respect to different mechanisms: destruction by inflammatory cells of the synovial fluid, pannus tissue and even ischemic bone necroses. Destruction via the synovial fluid is due to polymorphonuclear neutrophils (PMN) that can invade the pannus-free cartilage surface. In the absence of anti-proteases as a result of direct contact between the PMN and cartilage, enzymatic degradation can occur. Pannus tissue usually develops from the synovial insertion. Increased cellular proliferation in this area leads to a superficial pannus tissue that covers the cartilage (Fig. 4b); granulation tissue from the synovial insertion can destroy cortical bone and invade the subchondral tissue. The problem of isolated subchondral inflammatory foci is briefly discussed. The effector cells of cartilage destruction are identified as macrophages, PMN, and mast cells -cells that produce or activate destructive enzymes. Bone destruction is due to osteoclasts and even macrophages. Acute destruction via the granulation tissue may be followed by defect healing-scar tissue or chondroid metaplastic tissue can be present in the final stages of the disease. Ischemic bone necrosis leading to pseudocysts may also contribute to joint destruction.

Expression of c-fos gene inhibits proteoglycan synthesis in transfected chondrocyte

The effect of expression of c-fos gene on proteoglycan synthesis, one of the important markers of cartilage metabolism, was examined by introducing the c-fos DNA into HCS 2/8 chondrocytes. The [ 35S]sulfate incorporation into proteoglycan was decreased in the c-fos transfectants expressing exogenous c-fos mRNA, when compared to a control transfectant. A significant increase in transcription of MMP-3 with the suppressed transcription of aggrecan and TIMP-1 were also observed in the c-fos transfectants. Moreover, analysis of the effect of AP-1 proteins on the collagenase and TIMP-1 promoters in gastric carcinoma KKLS cells revealed that c-Fos combined with any of the Jun-related proteins failed to stimulate the TIMP-1 promoter, though collagenase promoter was effectively activated by any Fos/Jun-related protein heterocomplex. These findings indicate that the c-fos expression may govern the cartilage metabolism and hence may play an important role in the pathogenesis of joint destruction in arthritis.

Low dose corticosteroids in early rheumatoid arthritis. Can these drugs slow disease progression?

The role of corticosteroids in treating rheumatoid arthritis is controversial, but recourse to the available evidence of efficacy should guide patient management decisions. Earlier evidence suggested that symptomatic control could be improved for periods of 6 to 12 months, but not longer, without increasing doses to unacceptably high levels. The effect of corticosteroids on joint destruction has been unclear. Recent findings from a controlled clinical trial show that prednisolone 7.5 mg/day can significantly retard the rate of erosive progression in patients with relatively early disease (< 2 years' duration). These results have implications for both disease management and our understanding of the pathogenesis of joint destruction in rheumatoid arthritis.

THE NEUTROPHIL IN RHEUMATOID ARTHRITIS

The destructive capacity of the neutrophil has long been appreciated, and the presence of extraordinary numbers of neutrophils in the synovial fluid of patients with RA supports a role for these cells in the pathogenesis of joint destruction. In this article, we reviewed the current state of knowledge of neutrophil function in the inflammatory response, and emphasized the subjects of neutrophil/endothelial adhesion and the role of chemoattractants and cytokines in neutrophil mobilization. We also discussed the mechanisms of action of neutrophil destruction of cartilage and the interplay of signals between the neutrophil and the chondrocyte. The capacity of many of the drugs used to treat RA to interfere with one or several of these processes underscores the importance of the neutrophil in RA and suggests that future therapeutic strategies could target neutrophil activation within the synovial space.

Osteoporosis in rheumatoid arthritis: a molecular biological aspect of connective tissue gene activation.

Osteoporosis, especially the juxtaarticular osteoporosis of involved joints, is a characteristic manifestation of rheumatoid arthritis (RA). Histomorphometric studies suggest the existence of increased bone turnover in RA: impaired bone formation and hightened osteoclasic bone resorption. Recent studies show that important mediators in the pathogenesis of RA such as prostaglandin E, interleukin 1 (IL1) or tumor necrosis factor (TNF) alpha also play important roles in bone remodelling. Prostaglandin E2 promotes maturation of osteoclasts from hematopoietic precursor cells. IL1 inhibits collagen synthesis in osteoblasts. IL1 enhances collagenase and stromelysin gene expression and stimulates osteoclastic bone resorption. TNF alpha inhibits bone collagen synthesis and causes osteoclastic bone resorption. TNF alpha, and possibly IL1, enhances collagenase and stromelysin gene expression by stimulating the AP-1 promoter sites of the genes. Constitutive expression of c-fos induces joint destruction without lymphocyte infiltration in antigen-induced arthritis in mice, and supports cell growth of human rheumatoid synovial cells, possibly acting on the AP-1 sites. Furthermore, constitutive c-fos expression decreases collagen synthesis in osteoblasts and increases the mediator secretion from osteoblasts thereby stimulating osteoclastic bone resorption. These findings suggest that signal transduction through AP-1 transcriptional regulation sites may play an important role in the pathogenesis of joint destruction and osteoporosis in RA.

HLA-DR4Dw4-restricted T cell recognition of self antigen(s) in the rheumatoid synovial compartment

The pathogenesis of joint destruction in rheumatoid arthritis remains ill defined, although it is thought to be the result of tissue damage mediated by T cells. This prompted us to isolate and characterize in vivo activated T cells from rheumatoid arthritis synovial fluid in an attempt to determine their specificity. Heterogeneous synovial fluid cells, containing both adherent and non-adherent cell types, were recovered from joint aspirates and cultured in the presence of IL-2. After 2 weeks, the non-adherent cells were phenotyped as CD3-positive and TCR alpha beta-positive T cells. Polyclonal T cell lines were derived from four rheumatoid arthritis patients; of these, two proliferated, in a dose-dependent manner to only autologous synovial fluid in the presence of autologous or DR4Dw4 histocompatible antigen presenting cells. T cell proliferation to the synovial fluid could be inhibited by monomorphic anti-HLA-DR monoclonal antibody, but not by anti-DQ or anti-class I antibodies. T cell clones were established by limiting dilution of a synovial T cell line in the presence of autologous synovial fluid and DR4Dw4 histocompatible accessory cells. Examination of the antigen specificity of these T cell clones demonstrated that they were reactive with a component of synovial fluid. The results of these experiments suggest the presence of an MHC class II-restricted antigen in the rheumatoid arthritis synovial compartment that induces proliferation of in vivo activated T cells.

The synovium‐cartilage junction of the normal human knee: Implications for joint destruction and repair

The immunohistology of the synovium-cartilage junction was studied in 8 normal human knees, using monoclonal antibodies. In all joints at the junction with synovium, a vascular, wedge-shaped tongue of tissue was found to cover the cartilage surface. This marginal tissue overlying cartilage was in continuity with and was immunohistochemically similar to the adjacent synovial tissue, and contained cells possessing class II HLA antigens and antigens present on macrophages and type B synoviocytes. Periosteal tissue adjacent to the synovium-cartilage junction contained not only macrophages and other class II-positive cells, but also cells and matrix that stained with monoclonal antibodies specific for articular cartilage (keratan sulfate and type II collagen). This study demonstrates the presence of immunocompetent cells in tissue overlying the cartilage surface and adjacent to bone in normal human joints. It is likely that pannus in chronic inflammatory rheumatic disease develops by the recruitment of inflammatory cells augmenting this normal marginal tissue. Furthermore, overgrowth of tissue onto the cartilage surface may not be necessary in the pathogenesis of joint destruction in rheumatoid arthritis. In addition, our findings suggest that cells in the periosteum, rather than those in the marginal synovium, may be involved in attempted "repair" mechanisms, such as osteophyte formation.

Treatment of heart failure in haemochromatosis.

<h3>Background</h3> Hypoxia-inducible factor (HIF)-1α is a critical transcription regulator in cellular response to hypoxic condition. Hypoxic microenvironment exists in rheumatoid arthritis (RA) joints and we have reported that elevated HIF-1α promoted angiogenesis and inflammation in RA. Recent studies showed HIF-1α might promote osteoclast-mediated bone resorption in vitro. However, little was known about its role in RA joint destruction. <h3>Objectives</h3> To explore the correlation of synovial HIF-1α with joint destruction and its progression in RA. <h3>Methods</h3> Patients with active RA were followed up and X-ray assessment of hand/wrist was repeated at baseline and one year. Erosive disease was defined according to 2013 EULAR definition and radiographic progression was defined as the increase of total Sharp score more than 0.5 from baseline to one year. Synovial tissue was obtained from RA patients as well as OA and orthopedic arthropathies (Orth.A) patients. Serial tissue sections were stained with H&amp;E, immunohistochemically for CD3, CD20, CD38, CD68, CD15, CD34 and HIF-1α. Krenn9s synovitis score was semi-quantitatively assessed and the density of positive-staining cells was quantitatively determined. <h3>Results</h3> (1) Twenty five RA patients fulfilled 1 year follow-up, 84% were female, age (median and IQR, similarly hereinafter) was 50 (40–57) years, disease duration was 24 (10–48) months and disease activity SDAI was 35.0 (25.3–46.3). (2) HIF-1α expressed in lining and sublining area with intense nuclear and endochylema staining in RA synovium and the percentage of HIF-1α+ cells [57% (31%–77%)] was significantly higher than that in OA [<i>n</i>=13, 25% (9%–41%), <i>P</i>=0.022]or Orth.A [<i>n</i>=8, 21% (12%–38%), <i>P</i>=0.021, Fig.1]. The percentage of HIF-1α+ cells significantly correlated with subscore of synovial stroma activation, CD34+ microvessel count, CD68+ macrophage count and CD15+ neutrophil count (<i>r</i>=0.420–0.586, all <i>P</i>&lt;0.05). (3) Eleven (44%) RA patients had erosive disease at baseline. The percentage of HIF-1α+ cells was significantly higher in erosive patients than non-erosive patients [78% (49%–82%) vs 47% (23%–62%), <i>P</i>=0.014]. ROC curve analysis showed that the tradeoff value of synovial HIF-1α for diagnosing erosive disease was 69% with sensitivity 73% and specificity 100% (<i>AUC</i>=0.792, 95%<i>CI:</i> 0.574–1.010, <i>P</i>=0.014). Patients were then divided into high (n=8) and low synovial HIF-1α (n=17) groups. Total Sharp score and erosion subscore were higher in patients with high synovial HIF-1α than that in patients with low synovial HIF-1α [33 (14–69) vs 10 (4–24), 18 (11–25) vs 3 (2–12), respectively, all <i>P</i>&lt;0.05] (4) Eight (32%) RA patients showed radiographic progression at one year. The percentage of HIF-1α+ cells was significantly higher in progressive patients than non-progressive patients [80% (58%–85%) vs 49% (18%–63%), <i>P</i>=0.018]. ROC curve analysis showed that the tradeoff value of synovial HIF-1α for predicting 1-year radiographic progression was 66% with sensitivity 75% and specificity 82% (<i>AUC</i>=0.798, 95%<i>CI</i> :0.576–1.019, <i>P</i>=0.018). Univariate logistic regression showed that high level of synovial HIF-1α was a significant predictor of 1-year radiographic progression (<i>P</i>=0.011, <i>OR</i>=14.00, 95%<i>CI:</i> 1.841 to 106.465). <h3>Conclusions</h3> HIF-1α might play important roles in the pathogenesis of joint destruction in RA. <h3>Acknowledgements</h3> This work was supported by National Natural Science Foundation of China (81471597). <h3>Disclosure of Interest</h3> None declared