Update on synovitis

Anti-inflammatory effect of a novel piperazino-enaminone delivered by liposomes in a mouse model of hemophilic arthropathy

Hemophilic arthropathy (HA) is a condition caused by recurrent intra-articular bleeding in patients with hemophilia. Pro-inflammatory cytokines play a crucial role in the pathogenesis of HA. Our previous research demonstrated that a novel compound, piperazino-enaminone (JODI), effectively inhibited pro-inflammatory cytokines, including IL-6, MCP-1, MIP-1α, and MIP-1β, in a mouse model of hemarthrosis. This study aims to enhance the anti-inflammatory effect of JODI by employing nanoparticle delivery systems, which could potentially improve its poor water solubility. Here, we developed liposomes modified with polyethylene glycol (PEG) for the delivery of JODI (JODI-LIP), and found that JODI-LIP exhibited uniform size, morphology, good stability and in vitro release degree. JODI-LIP mitigated cytotoxicity of JODI, and significantly suppressed the production of pro-inflammatory cytokines (TNF-α and IL-1β) and nitric oxide (NO) release in RAW 264.7 cells stimulated by lipopolysaccharide (LPS), as well as the proliferation of human fibroblast-like synovial (HFLS) cells. In a murine model of HA, JODI-LIP demonstrated superior efficacy in ameliorating joint swelling and synovitis, compared to JODI. Importantly, JODI-LIP markedly reduced pro-inflammatory cytokines (TNF-α, IFN-γ, IL-33, and MCP-1) in injured joints. No hepatic or hematological toxicity was observed in mice treated with JODI-LIP. In summary, our results suggest that JODI-LIP holds promise as a therapeutic intervention for HA by attenuating pro-inflammatory cytokine levels.

Effects of tofacitinib therapy on arginine and methionine metabolites in association with vascular pathophysiology in rheumatoid arthritis: A metabolomic approach

Introduction

Rheumatoid arthritis (RA) has been associated with changes in lipid, arginine and NO metabolism with increased cardiovascular (CV) risk. The aim of this study is to evaluate the effect of tofacitinib, a Janus kinase (JAK) inhibitor, on arginine and methionine metabolism in correlation with inflammation, functional and pathological vascular changes during one-year treatment of patients with RA.

Materials and methods

Thirty RA patients with active disease were treated with either 5 mg bid or 10 mg bid tofacitinib for 12 months. We determined DAS28, CRP, IgM rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) levels. We assessed brachial artery flow-mediated vasodilation (FMD), carotid intima-media thickness (IMT) and pulse-wave velocity (PWV) by ultrasound at baseline and after 6 and 12 months. We also determined plasma L-arginine, L-citrulline, L-ornithine, inducible nitric oxide synthase (iNOS), asymmetric (ADMA) and symmetric dimethylarginine (SDMA), L-N-monomethyl-arginine (L-NMMA), cysteine, homocysteine, and methionine levels at these time points.

Results

Twenty-six patients (13 on each arm) completed the study. CRP, ESR and DAS28 decreased significantly during one-year treatment with tofacitinib. Arginine and ADMA showed a negative univariate correlation with CRP but not with FMD, PWV or IMT. Tofacitinib at 10 mg bid significantly increased L-arginine, L-ornithine, iNOS and methionine levels after 12 months. ADMA and SDMA levels did not change in our study. Methionine showed negative correlation with FMD at baseline and positive correlation with PWV after 12 months. No change was observed in FMD and PWV but a significant increase was measured in IMT at 6 and 12 months. Multivariate analysis indicated variable correlations of L-arginine, L-citrulline, ADMA, L-NMMA, homocysteine and methionine with DAS28, CRP, ESR and RF but not with anti-CCP after one-year treatment. With respect to vascular pathophysiology, only PWV and methionine correlated with each other.

Conclusion

One-year tofacitinib treatment suppressed systemic inflammation and improved functional status in RA. FMD, PWV have not been affected by one-year tofacitinib treatment., while IMT increased further despite treatment. Increased arginine and methionine might contribute to the anti-inflammatory effects of tofacitinib. Increased arginine availability with no changing ADMA may protect FMD and PWV from deterioration. The increase of IMT in the anti-inflammatory environment cannot be explained by arginine or methionine metabolism in this study.

Autologous Adipose-Derived Mesenchymal Stem Cells Combined with Shockwave Therapy Synergistically Ameliorates the Osteoarthritic Pathological Factors in Knee Joint

Adipose-derived mesenchymal stem cells (ADSCs) and shockwave (SW) therapy have been shown to exert a chondroprotective effect for osteoarthritis (OA). The results of this study demonstrated that autologous ADSCs had dose-dependent and synergistic effects with SW therapy (0.25 mJ/mm² with 800 impulses) in OA rat knee joint. Autologous, high-dose 2 × 10⁶ ADSCs (ADSC2 group) combined with SW therapy significantly increased the bone volume, trabecular thickness, and trabecular number among in the treatment groups. ADSC2 combined with SW therapy significantly reduced the synovitis score and OARSI score in comparison with other treatments. In the analysis of inflammation-induced extracellular matrix factors of the articular cartilage in OA, the results displayed that ADSC2 combined with SW therapy had a greater than other treatments in terms of reducing tumor necrosis factor-inducible gene (TSG)-6 and proteoglycan (PRG)-4, in addition to increasing tissue inhibitor matrix metalloproteinase (TIMP)-1 and type II collagen. Furthermore, ADSC2 combined with SW therapy significantly reduced the expression of inflammation-induced bone morphogenetic protein (BMP)-2 and BMP-6. Therefore, the results demonstrated that ADSC2 combined with SW therapy had a synergistic effect to ameliorate osteoarthritic pathological factors in OA joints.

Boron neutron capture synovectomy (BNCS) as a potential therapy for rheumatoid arthritis: radiobiological studies at RA-1 Nuclear Reactor in a model of antigen-induced arthritis in rabbits

Rheumatoid arthritis is a chronic autoimmune pathology characterized by the proliferation and inflammation of the synovium. Boron neutron capture synovectomy (BNCS), a binary treatment modality that combines the preferential incorporation of boron carriers to target tissue and neutron irradiation, was proposed to treat the pathological synovium in arthritis. In a previous biodistribution study, we showed the incorporation of therapeutically useful boron concentrations to the pathological synovium in a model of antigen-induced arthritis (AIA) in rabbits, employing two boron compounds approved for their use in humans, i.e., decahydrodecaborate (GB-10) and boronophenylalanine (BPA). The aim of the present study was to perform low-dose BNCS studies at the RA-1 Nuclear Reactor in the same model. Neutron irradiation was performed post intra-articular administration of BPA or GB-10 to deliver 2.4 or 3.9 Gy, respectively, to synovium (BNCS-AIA). AIA and healthy animals (no AIA) were used as controls. The animals were followed clinically for 2 months. At that time, biochemical, magnetic resonance imaging (MRI) and histological studies were performed. BNCS-AIA animals did not show any toxic effects, swelling or pain on palpation. In BNCS-AIA, the post-treatment levels of TNF-α decreased in four of six rabbits and IFN-γ levels decreased in five of six rabbits. In all cases, MRI images of the knee joint in BNCS-AIA resembled those of no AIA, with no necrosis or periarticular effusion. Synovial membranes of BNCS-AIA were histologically similar to no AIA. BPA-BNCS and GB-10-BNCS, even at low doses, would be therapeutically useful for the local treatment of rheumatoid arthritis.

The role of spinal fusion in the treatment of cervical synovial cysts: a series of 17 cases and meta-analysis

Object

This study was undertaken to compare surgical outcomes between patients with atlantoaxial versus subaxial cervical synovial cysts (CSCs) and to compare outcomes between patients who underwent decompression alone versus decompression and fusion for the treatment of CSCs.

Methods

The authors present a series of 17 cases involving patients treated at their institution and report the surgical outcomes. Due to the rarity of CSCs, a meta-analysis was conducted, and results of the literature search were combined with the case series to enhance the power of the study.

Results

Seventeen patients underwent surgical treatment for CSCs at our institution: 3 patients (17.6%) had atlantoaxial cysts and 14 (82.3%) had subaxial cysts. Of the 17 patients, 16 underwent a decompression and fusion; most patients experienced symptom resolution at last follow-up, and there were no cyst recurrences. A total of 54 articles (including the current series) and 101 patients were included in the meta-analysis. The mean age at presentation was 64 ± 13.9 years, and the most common symptoms were motor and sensory deficits. Forty-one patients (40.6%) presented with atlantoaxial cysts, and 60 (59.4%) with subaxial cysts. There were no significant differences between groups in terms of presenting symptoms, Nurick scores, surgical treatment, or surgical outcomes. Fifty-two patients (51.4%) underwent surgical decompression without fusion, while 49 patients (48.6%) underwent fusion. The preoperative Nurick scores were significantly lower in the fused group (p = 0.001), with an average score of 1.32 compared with 2.75 in the nonfused group. After a mean follow-up of 16.5 months, a difference of means analysis between final and preoperative Nurick scores revealed that patients who received a decompression alone improved on average 1.66 points (95% CI 1.03–2.29) compared with 0.8 points (95% CI 0.23–1.39) in the fused group (p = 0.004). However, there was no statistically significant difference in symptom resolution between the groups, and the rate of cyst recurrence was found to be 0%.

Conclusions

In this study, patients with CSCs had similar outcomes regardless of cyst location and regardless of whether they underwent decompression only or fusion. In the authors' institutional experience, 16 of 17 patients underwent fusion due to underlying spinal instability. While there were no reports of cyst recurrence in their series or in the literature in patients who only received decompression, this is likely due to the limited follow-up time available for the study population. Longer follow-up and prospective and biomechanical studies are needed to corroborate these findings.

Of mice and men: how animal models advance our understanding of T-cell function in RA

The involvement of autoreactive T cells in the pathogenesis of rheumatoid arthritis (RA) as well as in autoimmune animal models of arthritis has been well established; however, unanswered questions, such as the role of joint-homing T cells, remain. Animal models of arthritis are superb experimental tools in demonstrating how T cells trigger joint inflammation, and thus can help to further our knowledge of disease mechanisms and potential therapies. In this Review, we discuss the similarities and differences in T-cell subsets and functions between RA and mouse arthritis models. For example, various T-cell subsets are involved in both human and mouse arthritis, but differences might exist in the cytokine regulation and plasticity of these cells. With regard to joint-homing T cells, an abundance of synovial T cells is present in humans compared with mice. On the other hand, local expansion of type 17 T-helper (TH17) cells is observed in some animal models, but not in RA. Finally, whereas T-cell depletion therapy essentially failed in RA, antibody targeting of T cells can work, at least preventatively, in most arthritis models. Clearly, additional human and animal studies are needed to fill the gap in our understanding of the specific contribution of T-cell subsets to arthritis in mice and men.

Synovial cysts of the cervicothoracic junction causing myelopathy: report of 3 cases and review of the literature

Synovial cysts are uncommon pathological entities in patients with cervical degenerative spinal disease, and there are only a few reports in the literature. Treatment typically involves decompression; however, biomechanical data indicate that laminectomies in the cervical spine also result in cervical instability, specifically within the cervicothoracic junction, supporting the use of fusion as well. The authors describe the use of fusion with decompression in the treatment of 3 patients with cervicothoracic synovial cysts that presented in an acute fashion with associated myelopathy and neurological decline, and they review the diagnostic elements, histopathology, and treatment of these cysts. All 3 of the patients did well with decompression via a posterior approach with a single-level instrumented fusion from C-7 to T-1. Each patient regained complete neurological function and had no residual neurological deficits. These results are promising, although the sample size of 3 cases is too small to make any conclusive evaluations. Future studies incorporating Class I and Class II data are imperative to make firm conclusions regarding general management of this rare entity.

[Personalized medicine in rheumatology]

In rheumatology, especially in arthritides, early diagnosis and aggressive therapy may open up new dimensions of expectations, such as improvement of pain, prevention of structural, functional damage and better quality of life. Targeted (biological) therapy has brought new horizons in rheumatology. As it is a rather expensive treatment modality, it has been urgent to develop tools suitable for the prediction of therapeutic responses. Several clinical, immunological and genetic biomarkers have been established for this purpose. Among clinical markers, male sex, younger age, lower or even higher disease activity at baseline, combination treatment and quitting smoking may lead to better treatment outcome. Immunological biomarkers, such as C-reactive protein, seropositivity, peripheral blood or synovial cellular content have been associated with therapeutic responses. Finally, numerous genes or gene signatures may also predict the efficacy or safety of immunosuppressive drugs. Although sometimes there have been only few studies conducted that led to some controversy, some biomarkers have also been validated. This may lead us to optimism in terms of wider acceptance of personalized medicine in rheumatology.

Periarticular bone gain at proximal interphalangeal joints and changes in bone turnover markers in response to tumor necrosis factor inhibitors in rheumatoid and psoriatic arthritis

OBJECTIVE

Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are characterized by periarticular bone erosion; periarticular bone formation is a feature in PsA. The effect of anti-tumor necrosis factor-α (TNF-α) on periarticular bone remodeling is unclear in both diseases. Our aim was to assess the response of bone turnover markers (BTM) and hand bone mineral density (BMD) to anti-TNF over 3 years in RA and PsA.

METHODS

We measured serum bone-specific alkaline phosphatase (bone ALP), procollagen type-I N-propeptide (PINP), intact osteocalcin, C-terminal cross-linking telopeptides (CTX-I), urinary N-terminal cross-linking telopeptide of type-I collagen (NTX-I), and free deoxypyridinoline crosslinks (fDPD) at baseline, 1, 12, and 36 months. BMD measurements (hands/spine/hip) were obtained at 3 timepoints.

RESULTS

We recruited 62 patients (RA 35; PsA 27). BTM correlated significantly with hand BMD but not with central BMD. Low hand BMD was associated with RA and increased BTM. Following anti-TNF therapy, hip BMD declined while spine and hand BMD were unchanged. Periarticular BMD at proximal interphalangeal (PIP) joints increased while it decreased at metacarpophalangeal joints. Bone ALP increased steadily and was always higher in PsA. PINP and intact osteocalcin increased to a lesser extent, but resorption markers did not change.

CONCLUSION

At baseline, hand BMD was inversely associated with BTM. Bone formation rather than resorption markers better showed the bone response to anti-TNF. Despite a lack of effect on central BMD, the modest effect of anti-TNF on PIP BMD may provide evidence that BTM reflect specifically bone remodeling activity at periarticular sites of inflammation in RA and PsA.

Batch correction of microarray data substantially improves the identification of genes differentially expressed in rheumatoid arthritis and osteoarthritis

Background

Batch effects due to sample preparation or array variation (type, charge, and/or platform) may influence the results of microarray experiments and thus mask and/or confound true biological differences. Of the published approaches for batch correction, the algorithm “Combating Batch Effects When Combining Batches of Gene Expression Microarray Data” (ComBat) appears to be most suitable for small sample sizes and multiple batches.

Methods

Synovial fibroblasts (SFB; purity > 98%) were obtained from rheumatoid arthritis (RA) and osteoarthritis (OA) patients (n = 6 each) and stimulated with TNF-α or TGF-β1 for 0, 1, 2, 4, or 12 hours. Gene expression was analyzed using Affymetrix Human Genome U133 Plus 2.0 chips, an alternative chip definition file, and normalization by Robust Multi-Array Analysis (RMA). Data were batch-corrected for different acquiry dates using ComBat and the efficacy of the correction was validated using hierarchical clustering.

Results

In contrast to the hierarchical clustering dendrogram before batch correction, in which RA and OA patients clustered randomly, batch correction led to a clear separation of RA and OA. Strikingly, this applied not only to the 0 hour time point (i.e., before stimulation with TNF-α/TGF-β1), but also to all time points following stimulation except for the late 12 hour time point. Batch-corrected data then allowed the identification of differentially expressed genes discriminating between RA and OA. Batch correction only marginally modified the original data, as demonstrated by preservation of the main Gene Ontology (GO) categories of interest, and by minimally changed mean expression levels (maximal change 4.087%) or variances for all genes of interest. Eight genes from the GO category “extracellular matrix structural constituent” (5 different collagens, biglycan, and tubulointerstitial nephritis antigen-like 1) were differentially expressed between RA and OA (RA > OA), both constitutively at time point 0, and at all time points following stimulation with either TNF-α or TGF-β1.

Conclusion

Batch correction appears to be an extremely valuable tool to eliminate non-biological batch effects, and allows the identification of genes discriminating between different joint diseases. RA-SFB show an upregulated expression of extracellular matrix components, both constitutively following isolation from the synovial membrane and upon stimulation with disease-relevant cytokines or growth factors, suggesting an “imprinted” alteration of their phenotype.

Comparative assessment of vascular function in autoimmune rheumatic diseases: considerations of prevention and treatment

Numerous autoimmune-inflammatory rheumatic diseases have been associated with accelerated atherosclerosis or other types of vasculopathy leading to increased cardio- and cerebrovascular disease risk. Traditional risk factors, as well as the role of systemic inflammation including cytokines, chemokines, proteases, autoantibodies, adhesion receptors and others have been implicated in the development of these vascular pathologies. The characteristics of vasculopathies may significantly differ depending on the underlying disease. While classical accelerated atherosclerosis has been associated with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) or spondyloarthropathies (SpA), obliterative vasculopathy may rather be characteristic for systemic sclerosis (SSc) or mixed connective tissue disease (MCTD). Antiphospholipid antibodies have been implicated in vasculopathies underlying SLE, antiphospholipid syndrome (APS), RA and MCTD. There is also heterogeneity with respect to inflammatory risk factors. Cytokines, such as tumor necrosis factor-α (TNF-α) or interleukin 6 (IL-6) and immune complexes are primarily involved in arthritides, such as RA, SpA, as well as in SLE. On the other hand, autoantibodies including anti-oxLDL anti-cardiolipin and anti-β2GPI are rather involved in SLE- and APS-associated vasculopathies. Regarding the non-invasive assessment of vascular function, endothelial dysfunction, overt atherosclerosis and vascular stiffness may be indicated by brachial artery flow-mediated vasodilation (FMD), common carotid intima-media thickness (ccIMT) and aortic pulse-wave velocity (PWV), respectively. These abnormalities have been described in most inflammatory rheumatic diseases. While ccIMT and stiffness are relatively stable, FMD may be influenced by many confounding factors. In addition to traditional vasculoprotection, immunosuppressive agents including corticosteroids, traditional and biologic DMARDs may have significant vascular and metabolic effects. The official EULAR recommendations on the assessment and management of cardiovascular disease in arthritides have just been published, and similar recommendations in connective tissue diseases are to be developed soon.

Potential roles of microsomal prostaglandin E synthase-1 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease which primarily affects the synovial joints leading to inflammation, pain and joint deformities. Nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids, both of which inhibit cyclooxygenase (COX), have been extensively used for treating RA patients. Prostaglandin E synthase (PGES) is a specific biosynthetic enzyme that acts downstream of COX and converts prostaglandin (PG) H(2) to PGE(2). Among PGES isozymes, microsomal PGES-1 (mPGES-1) has been shown to be induced in a variety of cells and tissues under inflammatory conditions. The induction of mPGES-1 in the synovial tissue of RA patients is closely associated with the activation of the tissue by proinflammatory cytokines. Although selective mPGES-1 inhibitors have not yet been widely available, mice lacking mPGES-1 (mPGES-1(-/-) mice) have been generated to evaluate the physiological and pathological roles of mPGES-1 in vivo. Recent studies utilizing mPGES-1(-/-) mice have demonstrated the significance of mPGES-1 in the process of chronic inflammation and evocation of humoral immune response in autoimmune arthritis models. These recent findings highlight mPGES-1 as a novel therapeutic target for the treatment of autoimmune inflammatory diseases, including RA. Currently, both natural and synthetic chemicals are being tested for inhibition of mPGES-1 activity to produce PGE(2). The present review focuses on the recent advances in understanding the role of mPGES-1 in the pathophysiology of RA.

Synovial inflammation in patients with osteonecrosis of the femoral head

Much of the work aimed at elucidating the pathogenesis of osteonecrosis (ON) of the femoral head has focused on bone blood supply, with little attention to the surrounding synovial tissue (ST). We hypothesized that patients with ON exhibit synovial inflammation. Using immunohistological techniques, we found that a large population of patients with ON had synovial inflammation. Moreover, a population of ON patients had inflamed ST without having an inflammatory disease co-morbidity. The inflammatory infiltrate in these patients comprised primarily CD4(+) T cells and CD68(+) macrophages, the latter of which expressed increased levels of cellular adhesion molecules. Our results suggest the presence of a previously unrecognized population of ON patients without a diagnosed inflammatory co-morbidity and a highly inflammed synovium consisting primarily of a macrophage and CD4(+) T-cell infiltrate.

Gene expression profiles of systemic lupus erythematosus and rheumatoid arthritis

Gene expression profiling using microarray technology is being employed to define specific molecular mediators and pathways involved in immunobiology, to understand the intricate interplay of genes participating in the pathogenesis, and to develop biomarkers of disease activity in both systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). This review summarizes the latest information on the pathogenesis of SLE and RA and describes the utilization of microarray technology in these systemic autoimmune diseases.

Identification of intra-group, inter-individual, and gene-specific variances in mRNA expression profiles in the rheumatoid arthritis synovial membrane

Introduction

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive joint disease characterized by overexpression of pro-inflammatory/pro-destructive genes and other activating genes (for example, proto-oncogenes) in the synovial membrane (SM). The gene expression in disease is often characterized by significant inter-individual variances via specific synchronization/desynchronization of gene expression. To elucidate the contribution of the variance to the pathogenesis of disease, expression variances were tested in SM samples of RA patients, osteoarthritis (OA) patients, and normal controls (NCs).

Method

Analysis of gene expression in RA, OA, and NC samples was carried out using Affymetrix U133A/B oligonucleotide arrays, and the results were validated by real-time reverse transcription-polymerase chain reaction. For the comparison between RA and NC, 568 genes with significantly different variances in the two groups (P ≤ 0.05; Bonferroni/Holm corrected Brown-Forsythe version of the Levene test) were selected. For the comparison between RA and OA, 333 genes were selected. By means of the Kyoto Encyclopedia of Genes and Genomes, the pathways/complexes significantly affected by higher gene expression variances were identified in each group.

Results

Ten pathways/complexes significantly affected by higher gene expression variances were identified in RA compared with NC, including cytokine–cytokine receptor interactions, the transforming growth factor-beta pathway, and anti-apoptosis. Compared with OA, three pathways with significantly higher variances were identified in RA (for example, B-cell receptor signaling and vascular endothelial growth factor signaling). Functionally, the majority of the identified pathways are involved in the regulation of inflammation, proliferation, cell survival, and angiogenesis.

Conclusion

In RA, a number of disease-relevant or even disease-specific pathways/complexes are characterized by broad intra-group inter-individual expression variances. Thus, RA pathogenesis in different individuals may depend to a lesser extent on common alterations of the expression of specific key genes, and rather on individual-specific alterations of different genes resulting in common disturbances of key pathways.

Analysis of inflammatory leukocyte and endothelial chemotactic activity

The ingress of leukocytes into the synovium is a key event in inflammatory arthritis, such as rheumatoid arthritis. A number of soluble inflammatory mediators, such as chemokines, cytokines, and soluble adhesion molecules are involved in this event. It is feasible to test the chemotactic activity of mononuclear cells or endothelial cells using in vitro chemotaxis assays. The role of various chemotactic mediators in inflammatory synovitis can also be assessed using these systems by including these agents in the assay. There we describe monocyte and endothelial cell chemotaxis assays used in our laboratory.

Temporospatial expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in mouse antigen-induced arthritis

Several lines of evidence speak for an important role of matrix metalloproteinases (MMPs) in the development of progressive joint destruction. To better understand the role of MMPs and their tissue inhibitors (TIMPs) in this process, we have used the antigen-induced arthritis model to study the temporospatial expression of several MMPs and TIMPs during the progression of arthritis. Arthritis was induced by a single intra-articular injection of methylated bovine serum albumin (mBSA) into one or both knee joints of adult mice previously immunised against mBSA. Samples were collected at 3, 7, 21 and 42 days after induction of arthritis for histology and RNA extraction, and analysed by Northern hybridisation, histochemistry and immunohistochemistry for production of several MMPs and TIMPs -1, -2 and -3. A systematic analysis of MMP and TIMP mRNA levels in mouse knee joints demonstrated a general upregulation of both MMPs and TIMPs during progression of arthritis. Upregulation of MMP-9, -13 and -14 coincided with the advancement of cartilage degeneration, but the expression patterns of MMP-9 and -13 also followed the course of synovial inflammation. TIMPs were steadily upregulated throughout the examination period. Immunohistochemical localisation of MMPs and TIMPs suggested the synovium to be the major source of MMP and TIMP production in arthritis, although articular cartilage chondrocytes also showed an increased production of both MMPs and TIMPs.

Rheumatoid arthritis as a hyper-endoplasmic-reticulum-associated degradation disease

We introduce Synoviolin as a novel pathogenic factor in rheumatoid arthritis (RA). Experimental studies indicate that this endoplasmic reticulum (ER)-resident E3 ubiquitin ligase has important functions in the ER-associated degradation (ERAD) system, an essential system for ER homeostasis. Overexpression of Synoviolin in mice causes arthropathy with synovial hyperplasia, whereas heterozygous knockdown results in increased apoptosis of synovial cells and resistance to collagen-induced arthritis in mice. On the basis of these experimental data, we propose that excess elimination of unfolded proteins (that is, 'hyper-ERAD') by overexpression of Synoviolin triggers synovial cell overgrowth and hence a worsening of RA. Further analysis of the hyper-ERAD system may permit the complex pathomechanisms of RA to be uncovered.

Accelerated development of arthritis in mice lacking endothelial selectins

The selectins, along with very late antigen-4 and CD44, have been implicated in mediating leukocyte rolling interactions that lead to joint recruitment and inflammation during the pathogenesis of rheumatoid arthritis. Previously, we showed that P-selectin deficiency in mice resulted in accelerated onset of joint inflammation in the murine collagen-immunized arthritis model. Here, we report that mice deficient either in E-selectin or in E-selectin and P-selectin (E/P-selectin mutant) also exhibit accelerated development of arthritis compared with wild type mice in the CIA model, suggesting that these adhesion molecules perform overlapping functions in regulating joint disease. Analyses of cytokine and chemokine expression in joint tissue from E/P-selectin mutant mice before the onset of joint swelling revealed significantly higher joint levels of macrophage inflammatory protein-1α and IL-1β compared to wild-type mice. IL-1β remained significantly increased in E/P-selectin mutant joint tissue during the early and chronic phases of arthritis. Overall, these data illustrate the novel finding that E-selectin and P-selectin expression can significantly influence cytokine and chemokine production in joint tissue, and suggest that these adhesion molecules play important regulatory roles in the development of arthritis in E/P-selectin mutant mice.

Gene expression profile and synovial microcirculation at early stages of collagen-induced arthritis

A better understanding of the initial mechanisms that lead to arthritic disease could facilitate development of improved therapeutic strategies. We characterized the synovial microcirculation of knee joints in susceptible mouse strains undergoing intradermal immunization with bovine collagen II in complete Freund's adjuvant to induce arthritis (i.e. collagen-induced arthritis [CIA]). Susceptible DBA1/J and collagen II T-cell receptor transgenic mice were compared with CIA-resistant FVB/NJ mice. Before onset of clinical symptoms of arthritis, in vivo fluorescence microscopy of knee joints revealed marked leucocyte activation and interaction with the endothelial lining of synovial microvessels. This initial inflammatory cell response correlated with the gene expression profile at this disease stage. The majority of the 655 differentially expressed genes belonged to classes of genes that are involved in cell movement and structure, cell cycle and signal transduction, as well as transcription, protein synthesis and metabolism. However, 24 adhesion molecules and chemokine/cytokine genes were identified, some of which are known to contribute to arthritis (e.g. CD44 and neutrophil cytosolic factor 1) and some of which are novel in this respect (e.g. CC chemokine ligand-27 and IL-13 receptor α₁). Online in vivo data on synovial tissue microcirculation, together with gene expression profiling, emphasize the potential role played by early inflammatory events in the development of arthritis.

Targeting cellular adhesion molecules, chemokines and chemokine receptors in rheumatoid arthritis

The development of specific targeted therapies, such as anti-TNF-alpha treatment, for chronic inflammatory disorders such as rheumatoid arthritis, has significantly improved treatment, although not all patients respond. Targeting cellular adhesion molecules and chemokines/chemokine receptors as regulators of the extravasation and migration of leukocytes may provide a novel approach for the treatment of these diseases. Moreover, the possibility of developing small-molecule antagonists offers an excellent method for the oral delivery of compounds with a short half-life.

Targeting cathepsin L (CL) by specific ribozymes decreases CL protein synthesis and cartilage destruction in rheumatoid arthritis

The present study was undertaken to examine whether ribozymes cleaving specifically cathepsin L (CL) mRNA are able to decrease the synthesis of CL protease in rheumatoid arthritis synovial fibroblasts (RA-SF) and thereby reduce the invasiveness into cartilage both in vitro and in the SCID mouse coimplantation model of RA. Two different ribozymes that cleave CL mRNA specifically at positions 533 (RzCL533) and 790 (RzCL790) were generated. Using retroviral gene transfer, RA-SF were transduced with the ribozyme constructs or the empty vector. To examine the effect of the ribozymes on the mRNA level, quantitative analysis for CL mRNA was performed using real-time PCR. For evaluation on the protein level, ELISA using specific anti-CL antibodies was performed. In addition, transduced RA-SF were examined in vitro in a three-dimensional destruction assay evaluating their ability to degrade extracellular matrix produced by human chondrocytes. Matrix destruction was monitored by the release of soluble glycosaminoglycans (sGAG). Using the in vivo SCID mouse coimplantation model of RA, RzCL533-transduced RA-SF and control cells were coimplanted with human cartilage for 60 days. After being killed, invasion of RA-SF into the cartilage was evaluated by using a semiquantitative score. Transduction of RA-SF with RzCL533 and RzCL790 ribozymes decreased significantly the expression of CL mRNA to 44% (range 25-62%) and 20% (range 1-43%), respectively, when compared to mock-transduced cells. The protein concentration of CL in the cell culture supernatants of transduced RA-SF was decreased from 16.0 ng/ml in the mock constructs to 4.1 and 8.2 ng/ml (mean), respectively. Using the in vitro cartilage destruction assay, the release of sGAG decreased to 46 and 60%, respectively, after 14 days when compared to mock-transduced cells. In the SCID mouse coimplantation model of RA, RzCL533-transduced RA-SF revealed a significant lower cartilage invasion when compared to mock and untransduced cells. Using retroviral gene transfer, ribozymes cleaving CL mRNA inhibit specifically the synthesis of this matrix-degrading enzyme and reduce cartilage destruction in in vitro and in vivo models. Our study therefore suggests that ribozymes targeting CL could be a novel and efficient tool to inhibit joint destruction in RA.

Adenovirus mediated intra-articular expression of collagenase-3 (MMP-13) induces inflammatory arthritis in mice

OBJECTIVES

To better understand the role of collagenase-3 (MMP-13) in joint inflammation by investigating the consequences of transient overexpression of human collagenase-3 (matrix metalloproteinase-13 (MMP-13)), introduced by adenoviral gene delivery, in the mouse knee joint.

METHODS

A single dose (5x10(7) pfu) of recombinant adenovirus coding either for beta-galactosidase (RAdLacZ) or human MMP-13 (RAdMMP-13) was injected intra-articularly into the knee joint of adult mice. The joints were analysed at frequent intervals up to 4 weeks by histology, immunohistochemistry, and RNA analysis.

RESULTS

When RAdLacZ reporter virus was used, adenoviruses efficiently infected synovial cells, chondrocytes of articular cartilage, and hypertrophic chondrocytes of the growth plate. The infection was transient as no reporter gene activity was detected 3 weeks after the injection. After RAdMMP-13 injection into the knee joints, expression of human MMP-13 in joint tissues resulted in an arthritis characterised by recruitment of inflammatory cells and increased production of cytokines and chemokines, synovial hyperplasia, and pannus formation. After the loss of MMP-13 transgene expression at 3 weeks, these inflammatory changes began to diminish.

CONCLUSIONS

MMP-13 has a role in the onset of inflammatory reaction in synovium. However, damage to articular cartilage was only rarely detected after the short term overexpression of MMP-13.

Endothelial cell phenotypes in the rheumatoid synovium: activated, angiogenic, apoptotic and leaky

Endothelial cells are active participants in chronic inflammatory diseases. These cells undergo phenotypic changes that can be characterised as activated, angiogenic, apoptotic and leaky. In the present review, these phenotypes are described in the context of human rheumatoid arthritis as the disease example. Endothelial cells become activated in rheumatoid arthritis pathophysiology, expressing adhesion molecules and presenting chemokines, leading to leukocyte migration from the blood into the tissue. Endothelial cell permeability increases, leading to oedema formation and swelling of the joints. These cells proliferate as part of the angiogenic response and there is also a net increase in the turnover of endothelial cells since the number of apoptotic endothelial cells increases. The endothelium expresses various cytokines, cytokine receptors and proteases that are involved in angiogenesis, proliferation and tissue degradation. Associated with these mechanisms is a change in the spectrum of genes expressed, some of which are relatively endothelial specific and others are widely expressed by other cells in the synovium. Better knowledge of molecular and functional changes occurring in endothelial cells during chronic inflammation may lead to the development of endothelium-targeted therapies for rheumatoid arthritis and other chronic inflammatory diseases.

Rheumatoid arthritis: regulation of synovial inflammation

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.

Synoviolin/Hrd1, an E3 ubiquitin ligase, as a novel pathogenic factor for arthropathy

Rheumatoid arthritis (RA) is one of the most critical articular diseases with synovial hyperplasia followed by impairment of quality of life. However, the mechanism(s) that regulates synovial cell outgrowth is not fully understood. To clarify its mechanism(s), we carried out immunoscreening by using antirheumatoid synovial cell antibody and identified and cloned "Synoviolin/Hrd1", an E3 ubiquitin ligase. Synoviolin/Hrd1 was highly expressed in the rheumatoid synovium, and mice overexpressing this enzyme developed spontaneous arthropathy. Conversely, synoviolin/hrd1(+/-) mice were resistant to collagen-induced arthritis by enhanced apoptosis of synovial cells. We conclude that Synoviolin/Hrd1 is a novel causative factor for arthropathy by triggering synovial cell outgrowth through its antiapoptotic effects. Our findings provide a new pathogenetic model of RA and suggest that Synoviolin/Hrd1 could be targeted as a therapeutic strategy for RA.

The chemokines CCL5, CCL2 and CXCL12 play significant roles in the migration of Th1 cells into rheumatoid synovial tissue

As the T-cell population in the synovial tissue (ST) in rheumatoid arthritis (RA) is dominated by T helper (Th) 1 cells, this study was designed to examine whether there is a preferential migration of polarized T cells to ST, and to identify the chemokines responsible for the migration. This was done by developing 10 T-cell clones specific for an arbitrary antigen (mouse immunoglobulin G (IgG)) from the peripheral blood (PB) of a healthy donor sensitized to mouse IgG. The Th polarizations of the clones were determined by measuring secreted interferon-gamma and interleukin-4, following anti-CD3 stimulation. Migration to pools of RA ST cell-derived supernatants was analysed. Expression of the chemokine receptors CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CXCR3 and CXCR4 were analysed by flow cytometry. Th1 clones showed significantly higher migration to RA ST cell-derived supernatant compared with Th2 clones. Blocking of either of the chemokines, CCL5 or CCL2, strongly inhibited migration of the Th1 cells between 56 and 77%, while blocking of CXCL12 inhibited migration between 44 and 61%. Blocking of CXCL10 had only a minor inhibitory effect. Our results demonstrate a selective migration of Th1 cells to RA ST supernatant and that blocking either CCL5, CCL2 or CXCL12 significantly inhibits T-cell migration. This indicates that CCL5, CCL2 and CXCL12 play significant roles in attracting Th1 cells towards the RA ST, and may prove potent targets for obstructing T-cell migration to the synovium.

Osteopontin deficiency protects joints against destruction in anti-type II collagen antibody-induced arthritis in mice

Rheumatoid arthritis is one of the most critical diseases that impair the quality of life of patients, but its pathogenesis has not yet been fully understood. Osteopontin (OPN) is an extracellular matrix protein containing Arg-Gly-Asp (RGD) sequence, which interacts with alpha(v)beta3 integrins, promotes cell attachment, and cell migration and is expressed in both synovial cells and chondrocytes in rheumatoid arthritis; however, its functional relationship to arthritis has not been known. Therefore, we investigated the roles of OPN in the pathogenesis of inflammatory process in a rheumatoid arthritis model induced by a mixture of anti-type II collagen mAbs and lipopolysaccharide (mAbs/LPS). mAbs/LPS injection induced OPN expression in synovia as well as cartilage, and this expression was associated with joint swelling, destruction of the surface structures of the joint based on scanning electron microscopy, and loss of toluidine blue-positive proteoglycan content in the articular cartilage in wild-type mice. In contrast, OPN deficiency prevented the mice from such surface destruction, loss of proteoglycan in the articular joint cartilage, and swelling of the joints even when the mice were subjected to mAbs/LPS injection. Furthermore, mAbs/LPS injection in wild-type mice enhanced the levels of CD31-positive vessels in synovia and terminal deoxynucleotidyltransferase-mediated UTP end labeling-positive chondrocytes in the articular cartilage, whereas such angiogenesis as well as chondrocyte apoptosis was suppressed significantly in OPN-deficient mice. These results indicated that OPN plays a critical role in the destruction of joint cartilage in the rheumatoid arthritis model in mice via promotion of angiogenesis and induction of chondrocyte apoptosis.

Homing chemokines in rheumatoid arthritis

In about 20% of patients with rheumatoid arthritis, B and T lymphocytes recruited into the inflamed synovium are organized into complex microstructures, which resemble secondary lymphoid organs. The development of such lymphoid aggregates with germinal centers appears to contribute to the pathogenesis of the disease. Growing evidence indicates that chemokines and their receptors control the recruitment and positioning of leukocytes as well as their organization into node-like lymphoid structures. Here, we comment on recent studies highlighting the importance of chemokines in rheumatoid arthritis, in particular of B-cell-activating chemokine-1 in lymphoid neogenesis in the inflamed synovium.

Chemokines in autoimmune disease

Growing evidence indicates that structural cells play a crucial role in the chronic inflammation of autoimmunity by their recruitment of chemokine-dependent cells. Members of the two functional classes of chemokines, inflammatory and homeostatic, seem to be involved in lymphocyte recruitment and survival, and in establishing ectopic lymphoid structures in the target organs of autoimmune diseases. Results from animal models suggest that chemokines are reasonable therapeutic targets in autoimmunity.

A novel role for interleukin-18 in adhesion molecule induction through NF kappa B and phosphatidylinositol (PI) 3-kinase-dependent signal transduction pathways

Interleukin-18 (IL-18) is a novel proinflammatory cytokine found in serum and joints of patients with rheumatoid arthritis (RA). We studied a novel role for IL-18 in mediating cell adhesion, a vital component of the inflammation found in RA and other inflammatory diseases. We examined the expression of cellular cell adhesion molecules E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) on endothelial cells and RA synovial fibroblasts using flow cytometry. Adhesion of the monocyte-like cell line HL-60 to endothelial cells was determined by immunofluorescence. IL-18 significantly enhanced ICAM-1 and VCAM-1 expression on endothelial cells and RA synovial fibroblasts. In addition, IL-18 induced E-selectin expression on endothelial cells and promoted the adhesion of HL-60 cells to IL-18-stimulated endothelial cells. Neutralizing anti-VCAM-1 and anti-E-selectin could completely inhibit HL-60 adherence to endothelial cells. IL-18-induced adhesion molecule expression appears to be mediated through nuclear factor kappa B (NF kappa B) and phosphatidyl-inositol 3 kinase (PI 3-kinase) since addition of inhibitors to either NF kappa B (pyrrolidine dithiocarbamate and N-acetyl-l-cysteine) or PI 3-kinase (LY294002) inhibited RA synovial fibroblast VCAM-1 expression by 50 to 60%. Addition of both inhibitors resulted in inhibition of VCAM-1 expression by 85%. In conclusion, the ability of IL-18 to induce adhesion molecule expression on endothelial cells and RA synovial fibroblasts indicates that IL-18 may contribute to RA joint inflammation by enhancing the recruitment of leukocytes into the joint. IL-18 requires NF kappa B as well as PI 3-kinase to induce VCAM-1 on RA synovial fibroblasts, suggesting that there may be two distinct pathways in IL-18-induced adhesion molecule expression.