Abnormal networks of immune response-related molecules in bone marrow cells from patients with rheumatoid arthritis as revealed by DNA microarray analysis

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic synovitis that progresses to destruction of cartilage and bone. Bone marrow (BM) cells have been shown to contribute to this pathogenesis. In this study, we compared differentially expressed molecules in BM cells from RA and osteoarthritis (OA) patients and analyzed abnormal regulatory networks to identify the role of BM cells in RA.

METHODS

Gene expression profiles (GEPs) in BM-derived mononuclear cells from 9 RA and 10 OA patients were obtained by DNA microarray. Up- and down-regulated genes were identified by comparing the GEPs from the two patient groups. Bioinformatics was performed by Expression Analysis Systemic Explorer (EASE) 2.0 based on gene ontology, followed by network pathway analysis with Ingenuity Pathways Analysis (IPA) 7.5.

RESULTS

The BM mononuclear cells showed 764 up-regulated and 1,910 down-regulated genes in RA patients relative to the OA group. EASE revealed that the gene category response to external stimulus, which included the gene category immune response, was overrepresented by the up-regulated genes. So too were the gene categories signal transduction and phosphate metabolism. Down-regulated genes were dominantly classified in three gene categories: cell proliferation, which included mitotic cell cycle, DNA replication and chromosome cycle, and DNA metabolism. Most genes in these categories overlapped with each other. IPA analysis showed that the up-regulated genes in immune response were highly relevant to the antigen presentation pathway and to interferon signaling. The major histocompatibility complex (MHC) class I molecules, human leukocyte antigen (HLA)-E, HLA-F, and HLA-G, tapasin (TAP) and TAP binding protein, both of which are involved in peptide antigen binding and presentation via MHC class I molecules, are depicted in the immune response molecule networks. Interferon gamma and interleukin 8 were overexpressed and found to play central roles in these networks.

CONCLUSIONS

Abnormal regulatory networks in the immune response and cell cycle categories were identified in BM mononuclear cells from RA patients, indicating that the BM is pathologically involved in RA.

[Comparison of the status of STAT4 tyrosine phosphorylation in peripheral T-lymphocytes induced by IL-12 in rheumatoid arthritis and osteoarthritis]

OBJECTIVE

To compare the levels of STAT4 tyrosine phosphorylation in peripheral T-lymphocytes induced by IL-12 in rheumatoid arthritis (RA) and osteoarthritis (OA).

METHODS

From May 2007 to August 2009, peripheral blood mononuclear cells (PBMCs) were isolated from RA patients [RA group, all the cases were female, the age was from 28 to 55 years with an average of (45.0 +/- 13.0) years] and OA patients [OA group, all the cases also were female; the age was from 55 to 75 years with an average of (67.0 +/- 9.6) years]. The purity of T-lymphocytes from PBMCs was accredited by flow cytometry. The IL-12 of 50 ng/ml added in T-lymphocytes, the levels of STAT4 tyrosine phosphorylation were detected by western blot after different time intervals (0, 10, 30, 60 min).

RESULTS

The purity of T-lymphocytes were above 91% through diremption and depuration for peripheral blood monouclear cells. The levels of STAT4 tyrosine phosphorylation in T-lymphocytes from RA induced by IL-12 were higher than that from OA in the different times (10, 30, 60 min); after 30 min, its levels from RA and OA achieved to crest value.

CONCLUSION

STAT4 in peripheral T-lymphocytes of rheumatoid arthritis was more easily to be activated than osteoarthritis.

[Circumannular features of non-specific resistance in patients with osteoarthrosis in mid-lattitudes]

Modified cosinor-analysis was used to calculate biorhythmologic characteristics (period, amplitude, phase, mesor) of the circumannual rhythm of neuroendocrine regulation parameters, the state of bioradical hemostasis, and protein components of non-specific resistance in patients with osteoarthrosis living in moderate climates. Near-annual rhythms of these parameters are described. The chronological analysis indicates that strenuouos activity of the regulatory systems responsible for adaptive reactions of the organism falls within the periods from March to May and from August to October. Variability of the above parameters is shown to be related to the efficacy of osteoarthrosis therapy in different phases of the near-annual rhythm.

Widespread scleredema associated with paraproteinemia and generalized osteoarthritis in an HLA-B39 positive patient

Scleredema adultorum (SA) is a rare sclerotic disorder characterized by non-pitting induration of the neck with acral progression, sparing hands and feet. We report on a 57-year-old male with severe SA associated with paraproteinemia, treated with methotrexate. Such widespread skin thickening followed by severe movement restriction and inability to function on daily basis, as in our patient, has never been described. Severe osteoarthritis and finding of HLA-B39 allele in association with SA has not been previously described either. To the best of our knowledge, up to 40 patients with SA associated with paraproteinemia has been reported so far, and currently, there is no established effective treatment protocol. In our patient, low-dose methotrexate resulted in stiffness reduction, increased motility of the trunk and extremities, and ability to function on daily basis. We believe that any information about treatment outcome in SA patients should be disseminated in order to establish consensual treatment protocol for this rare disease.

[Evolution of the pharmacological management of osteoarthritis: the biologics]

Proinflammatory cytokines such as IL-1 β et TNF α are implicated in osteoarthritis where they contribute to the local synovitis. Blocking IL-1 β is a promising tool in experimental animal's model of osteoarthritis (OA). So far in human clinical trials using IL-1 blockers, the results are inconclusive. The blockade of TNF α seems more appropriated for inflammatory forms of hand OA with some encouraging results. Intra-articular administration of biologics is hampered by their short resident time into the joint. Gene therapy is one of the possible way to prolong the local intra-articular delivery of biologics.

MCP-1 production in temporomandibular joint inflammation

Synovitis, which is characterized by the infiltration of inflammatory cells, often accompanies progression of temporomandibular joint disorder (TMD) symptoms. Because IL-1β is elevated in synovial fluids obtained from TMDs, we hypothesized that IL-1β-responsive genes in synoviocytes may help identify the putative genes associated with synovitis. Using microarray analysis, we found that monocyte chemoattractant protein-1 (MCP-1) mRNA levels were elevated in IL-1β-stimulated synoviocytes. MCP-1 is a member of the chemokine superfamily. The production of MCP-1 was increased in synoviocytes treated with IL-1β. When IL-1β was injected into the cavities of rat TMJs, inflammatory cells and MCP-1-positive cells were detected in the synovial tissues. Furthermore, MCP-1 levels were higher in synovial fluids from individuals with pain compared with those without pain. Inhibitors of MAP-kinases and NF-κB reduced IL-1β-induced MCP-1 production. These results suggest that MCP-1 stimulated by IL-1β is one of the factors associated with the inflammatory progression of TMDs.

Expression and functional role of adenosine receptors in regulating inflammatory responses in human synoviocytes

BACKGROUND AND PURPOSE

Adenosine is an endogenous modulator, interacting with four G-protein coupled receptors (A(1), A(2A), A(2B) and A(3)) and acts as a potent inhibitor of inflammatory processes in several tissues. So far, the functional effects modulated by adenosine receptors on human synoviocytes have not been investigated in detail. We evaluated mRNA, the protein levels, the functional role of adenosine receptors and their pharmacological modulation in human synoviocytes.

EXPERIMENTAL APPROACH

mRNA, Western blotting, saturation and competition binding experiments, cyclic AMP, p38 mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-kappaB activation, tumour necrosis factor alpha (TNF-alpha) and interleukin-8 (IL-8) release were assessed in human synoviocytes isolated from patients with osteoarthritis.

KEY RESULTS

mRNA and protein for A(1), A(2A), A(2B) and A(3) adenosine receptors are expressed in human synoviocytes. Standard adenosine agonists and antagonists showed affinity values in the nanomolar range and were coupled to stimulation or inhibition of adenylyl cyclase. Activation of A(2A) and A(3) adenosine receptors inhibited p38 MAPK and NF-kappaB pathways, an effect abolished by selective adenosine antagonists. A(2A) and A(3) receptor agonists decreased TNF-alpha and IL-8 production. The phosphoinositide 3-kinase or G(s) pathways were involved in the functional responses of A(3) or A(2A) adenosine receptors. Synoviocyte A(1) and A(2B) adenosine receptors were not implicated in the inflammatory process whereas stimulation of A(2A) and A(3) adenosine receptors was closely associated with a down-regulation of the inflammatory status.

CONCLUSIONS AND IMPLICATIONS

These results indicate that A(2A) and A(3) adenosine receptors may represent a potential target in therapeutic modulation of joint inflammation.

Expression of Tn and sialyl Tn antigens in synovial tissues in rheumatoid arthritis

OBJECTIVES

The carbohydrate chains represented by mucins (MUCs) are expressed by a variety of normal and malignant secretory epithelial cells and induce a variety of immunoreactions. Tn and sialyl Tn antigens are tumour-associated carbohydrate antigens which are borne on the core proteins of mucins. The purpose of this study is to investigate the existence of tumour-associated carbohydrate antigens in rheumatoid arthritis (RA).

METHODS

. We examined the expression of Tn and sialyl Tn antigens in synovial tissues from RA and osteoarthritis (OA) patients by immunohistochemistry. In addition, mucins from synovial fluid (SF) from RA patients are purified by gel filtration and density gradient ultracentrifugation and the existence of these antigens examined by dot and Western blotting.

RESULTS

We found that Tn and sialyl Tn antigens were strongly expressed in synovial cells and infiltrating mononuclear cells on the sublining layer and lymphoid follicles in synovial tissues in RA compared with those in osteoarthritis. Tn and sialyl Tn antigens were detected in purified mucins of SF from RA patients.

CONCLUSIONS

Tumour-like synovial hyperplasia cells expressed Tn and sialyl Tn antigens. This finding suggests that the mucins exhibiting with abnormal glycosylation may be in part responsible for synovial hyperplasia, leading to the joint destruction in the pathogenesis of RA.

Effects of glucosamine hydrochloride and chondroitin sulphate, alone and in combination, on normal and interleukin-1 conditioned equine articular cartilage explant metabolism

REASONS FOR PERFORMING STUDY

Clinical trials in human and veterinary literature have documented the benefits of oral nutraceutical joint supplements containing glucosamine (GU) and chondroitin sulphate (CS) to treat mild to moderate osteoarthritis, but the effects of these components have not yet been conclusively determined.

OBJECTIVES

To assess varying dosages of GU and CS on normal and interleukin-1alpha (IL-1) conditioned equine cartilage explants and rationalise the use of these products.

HYPOTHESIS

Treatment would not be detrimental to cartilage metabolism and higher dosages and the combination of GU and CS would be more beneficial than lower dosages and. GU or CS alone.

METHODS

Articular cartilage explants collected from the femoral trochlea and condyles were cultured in normal and IL-1 conditioned media. Treatment groups included 0, 12.5, 25,125 and 250 microg/ml concentrations of GU alone, CS alone, or GU+CS in combination. Glycosaminoglycan (GAG) synthesis and total GAG content in the explants and media were analysed.

RESULTS

There were no detrimental effects of GU, CS or GU+CS on cartilage metabolism. High dosages of GU+CS reduced total GAG release into the media (degradation).

CONCLUSIONS

Our results suggests that GU+CS may prevent cartilage GAG degradation.

POTENTIAL RELEVANCE

The combination of GU and CS may be more effective in preventing or treating osteoarthritis in horses than either product alone.

Increased activity and expression of histone deacetylase 1 in relation to tumor necrosis factor-alpha in synovial tissue of rheumatoid arthritis

INTRODUCTION

The purpose of this study was to investigate the profile of histone deacetylase (HDAC) expression in the synovial tissue of rheumatoid arthritis (RA) compared with that of normal control and osteoarthritis (OA), and to examine whether there is a link between HDAC activity and synovial inflammation.

METHODS

HDAC activity and histone acetyltransferase (HAT) activity were determined in nuclear extracts of total synovial tissue surgically obtained from normal, OA and RA joints. The level of cytoplasmic tumor necrosis factor a (TNFα) fraction was measured by ELISA. Total RNA of synovial tissue was used for RT-PCR of HDAC1-8. In synovial fibroblasts from RA (RASFs), the effects of TNFα on nuclear HDAC activity and class I HDACs (1, 2, 3, 8) mRNA expressions were examined by quantitative real-time PCR. The protein expression and distribution of class I HDACs were examined by Western blotting.

RESULTS

Nuclear HDAC activity was significantly higher in RA than in OA and normal controls and correlated with the amount of cytoplasmic TNFα. The mRNA expression of HDAC1 in RA synovial tissue was higher than in OA and normal controls, and showed positive correlation with TNFα mRNA expression. The protein level of nuclear HDAC1 was higher in RA synovial tissue compared with OA synovial tissue. Stimulation with TNFα significantly increased the nuclear HDAC activity and HDAC1 mRNA expression at 24 hours and HDAC1 protein expression at 48 hours in RASFs.

CONCLUSIONS

Our results showed nuclear HDAC activity and expression of HDAC1 were significantly higher in RA than in OA synovial tissues, and they were upregulated by TNFα stimulation in RASFs. These data might provide important clues for the development of specific small molecule HDAC inhibitors.

IL-23 induces receptor activator of NF-kappaB ligand expression in fibroblast-like synoviocytes via STAT3 and NF-kappaB signal pathways

Interleukin (IL)-23 stimulates T lymphocytes to produce inflammatory molecules, which can cause inflammatory arthritis. This study was undertaken to explore the role of IL-23 in stimulating the expression of the receptor activator of the nuclear factor kappa B (NF-kappaB) ligand (RANKL) and osteoclastogenic activity in human fibroblast-like synoviocytes (FLS). These cells were separated from the synovium of patients with rheumatoid arthritis (RA-FLS) and osteoarthritis (OA-FLS) and stimulated with IL-23. RANKL expression was measured by real-time polymerase chain reaction (PCR) amplification and immunostaining. Osteoclast precursor cells were cocultured with IL-23-stimulated RA-FLS and OA-FLS and subsequently stained for tartrate-resistant acid phosphatase (TRAP) activity. IL-23 upregulated RANKL expression in RA-FLS. The expression of RANKL mRNA and protein was blocked completely by inhibitors of NF-kappaB (parthenolide) or of the JAK II-STAT3 pathway (AG490), showing that the RANKL expression pathway is mediated by NF-kappaB and STAT3. TRAP-positive osteoclastogenesis was enhanced in IL-23-stimulated FLS. RA-FLS were more responsive to IL-23 in terms of their RANKL expression than OA-FLS or normal FLS. Thus, IL-23 appears to induce joint inflammation and bone destruction by stimulating RANKL expression in RA-FLS. These interactions between IL-23 and FLS indicate possible new therapeutic approaches for treating bone destruction in patients with inflammatory diseases.

Citrullinated antigens as C1q-binding and monoclonal rheumatoid factor (mRF)-binding peptides in synovial fluids from rheumatoid arthritis patients

OBJECTIVE

Previous studies have demonstrated that immune complexes (ICs) may be involved in the pathogenesis of rheumatoid arthritis (RA). However, autoantigens contained in rheumatoid ICs remain to be elucidated. In the present study, we investigated whether the peptides captured by C1q and monoclonal rheumatoid factor (mRF), presumably associated with ICs, were citrullinated in synovial fluids from patients with RA.

METHODS

Sixteen rheumatoid arthritis synovial fluids (RASFs), 7 osteoarthritis synovial fluids (OASFs), and 20 sera from RA patients were used for experiments. ICs were measured using commercially available kits based on the C1q-binding (C1q-IC) and mRF-binding (mRF-IC) assays. Citrullination of the peptides captured by C1q and mRF was detected by anti-modified citrulline antibody (Senshu Ab) after chemical modification.

RESULTS

There was a significant correlation between levels of citrullination of C1q-binding peptides and those of mRF-binding peptides in RASFs (r=0.77), both of which were significantly higher than those in OASFs. No citrullinated Ags captured by C1q and mRF were detected in sera from patients with RA.

CONCLUSIONS

We have demonstrated the presence of citrullinated Ags as C1q- and mRF-binding peptides in RASF. We suggest that citrullinated Ags may contribute to the pathogenesis of RA through IC formation in the joint.

Elevated expression of interleukin-7 receptor in inflamed joints mediates interleukin-7-induced immune activation in rheumatoid arthritis

OBJECTIVE

To evaluate the expression and functional ability of the high-affinity interleukin-7 receptor (IL-7Ralpha) in patients with rheumatoid arthritis (RA).

METHODS

Expression of IL-7Ralpha and IL-7 was determined in synovial tissue from RA patients and was compared with that in synovial tissue from patients with undifferentiated arthritis (UA) and osteoarthritis (OA). IL-7Ralpha expression on CD4 T cells, CD19 B cells, and CD14 monocyte/macrophages from RA synovial tissue, synovial fluid, and peripheral blood was also assessed. The proliferative capacity of IL-7Ralpha(bright) and IL-7Ralpha(dim/-) T cells was measured. In addition, we examined IL-7R blockade with soluble human IL-7Ralpha (hIL-7Ralpha) in the prevention of immune activation of peripheral blood mononuclear cells.

RESULTS

We found significantly higher IL-7Ralpha expression in RA and UA synovial tissue than in OA synovial tissue, and the level of IL-7Ralpha expression correlated significantly with the levels of CD3 and IL-7 expression. CD4 T cells from RA synovial fluid and synovial tissue strongly expressed IL-7Ralpha. A substantial percentage of B cells and macrophages from RA synovial fluid and synovial tissue also expressed IL-7Ralpha, although less prominently than T cells. We found that peripheral blood IL-7Ralpha(bright) T cells that did not express FoxP3 were highly proliferative as compared with IL-7Ralpha(dim/-) T cells that did express high levels of FoxP3. Soluble hIL-7Ralpha inhibited IL-7-induced proliferation and interferon-gamma production by mononuclear cells from RA patients.

CONCLUSION

Our data suggest that enhanced expression of IL-7Ralpha and IL-7 in RA patients contributes significantly to the joint inflammation by activating T cells, B cells, and macrophages. The inhibition of IL-7R-mediated immune activation by soluble hIL-7Ralpha further indicates an important role of IL-7Ralpha in inflammatory responses in RA, suggesting IL-7Ralpha as a therapeutic target for immunotherapy in RA.

Autoantibodies to glucose‐6‐phosphate isomerase are elevated in the synovial fluid of rheumatoid arthritis patients

OBJECTIVE

This study investigated whether anti-glucose-6-phosphate isomerase (GPI) antibody in the synovial fluid is specifically related to human rheumatoid arthritis (RA).

METHODS

Synovial fluid was collected from patients with RA, osteoarthritis (OA), gout, Behcet's disease, or ankylosing spondylitis. GPI-binding activity was measured in the synovial fluid using a surface plasmon resonance (SPR) biosensor.

RESULTS

The mean level of anti-GPI signal in the synovial fluid of RA patients was significantly elevated compared with that of OA patients (2.84 +/- 1.41 AU versus 1.19 +/- 0.42 AU, respectively; p < 0.0001). Anti-GPI signals in the synovial fluids of patients with non-rheumatoid arthritis, such as gout, Behcet's disease, or ankylosing spondylitis were significantly lower than in the synovial fluid of RA patients (p < 0.005), and were similar to those of OA patients.

CONCLUSION

Our study indicates that anti-GPI antibody in the synovial fluid is specifically related to RA, and suggests that GPI and its autoantibody might be important in the pathogenesis of human RA.

[T cell proliferative response and antibody formation to citrullinated collagen type II in patients with rheumatoid arthritis]

OBJECTIVE

To investigate the T cell proliferative response and antibody formation to citrullinated collagen type II (Cit-CII) in patients with rheumatoid arthritis (RA), and explore whether autoreactive T cells responding to Cit-CII plays a role in the pathogenesis of RA.

METHODS

Arginine residues of bovine collagen type II (CII) were converted to citrulline residues by peptidylarginine deiminase (PAD). Peripheral blood samples were collected from 34 RA patients, and 18 sex- and age-matched controls, including 6 osteoarthritis patients and 12 healthy blood donors. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured with Cit-CII, CII, or fetal bovine serum RPMI 1640 fluid, phytohemagglutinin (PHA), or citrullinated buffer as controls. Cellular reactivity levels against Cit-CII and CII were investigated by measuring the proliferation of PBMCs to calculate the stimulation index (SI). ELISA was used to detect the presence of antibodies against Cit-CII and CII.

RESULTS

The positive rate of T cell proliferative response to Cit-CII of the RA group was 32.4% (11/34), significantly higher than that of the control group (0, P < 0.05). The positive rate of T cell proliferative response to CII of the RA group was 35.3% (12/34), significantly higher than that of the control group (11.1%, P < 0.05). Interestingly, Cit-CII could not elicit a better T cell proliferative response than CII did. In the RA patients, the anti-Cit-CII antibody positive rate was 52.9% (18/34), significantly higher than that of the anti-CII antibody positive rate [32.4% (11/34), P < 0.05). The serum IgG anti-CII antibody positive rate of the patients with positive T cell responses to CII was 58.3% (7/12), significantly higher than that of the patients with negative T cell responses to CII [18.2% (4/22), P < 0.05]. The serum IgG anti-CII antibody positive rate of the patients with positive T cell responses to Cit-CII was 72.7% (8/11), significantly higher than that of the patients with negative T cell responses to Cit-CII [43.5% (10/23), P < 0.05].

CONCLUSION

The recognition of Cit-CII by circulating IgG antibodies is a RA-specific serological phenomenon. The formation of CII antibody in the RA patients may be related to B cell activation mediated by CII specific T cells. The role of Cit-CII in RA cellular immune need be further studied.

[Genotype and haplotype analysis of killer cell immunoglobulin-like receptors in ankylosing spondylitis]

OBJECTIVE

To investigate the association of killer cell immunoglobulin-like receptors (KIR) genotype and haplotype with ankylosing spondylitis (AS).

METHODS

Peripheral blood samples were collected from 105 AS patients, 62 patients of osteoarthritis (OA), and 412 randomly selected healthy controls. Polymerase chain reaction with sequence-specific primers (PCR-SSP) was used to detect the KIR genotype and haplotype.

RESULTS

The genotype frequency of 3DL3-2DL3-2DL1-2DP1-2DL4-3DL1-2DS4-3DL2 (6.67%) was significantly lower in the AS patients than in the control subjects (20.15%) and OA patients (17.74%, P = 0.001, 0.037 respectively). The genotype frequency of 3DL3-2DL3-2DL2-2DL1-2DP1-2DLA-3DL1-2DL5-2DS1-2DS2-2DS3-2DS4-2DS5-3DS1-3DL2 and 3DL3-2DL3-2DL2- 2DL1-2DP1-2DL4-3DL1-2DL5-2DS1-2DS4-3DL2 of the AS patients (9.52%, 5.71%)was significantly higher than that of the controls(2.18%, 0.49%; P = 0.001, 0.001), and these two genotypes were not detected in the OA patients. There were not significant differences in the haplotypes A and B among the AS patients, OA patients, and healthy controls.

CONCLUSION

KIR genotypes may be associated with the susceptibility to AS.

The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis

Osteoarthritis (OA) is one of the most common and disabling chronic joint disorders affecting horses, dogs and humans. Synovial inflammation or synovitis is a frequently observed phenomenon in osteoarthritic joints and contributes to the pathogenesis of OA through formation of various catabolic and pro-inflammatory mediators altering the balance of cartilage matrix degradation and repair. Catabolic mediators produced by the inflamed synovium include pro-inflammatory cytokines, nitric oxide, prostaglandin E(2) and several neuropeptides, which further contribute to the pathogenesis of OA by increasing cartilage degradation. Recent studies suggest that substance P, corticotropin-releasing factor, urocortin and vasoactive intestinal peptide may also be involved in OA development, but the precise role of these neuropeptides in the pathogenesis of OA is not known. Since increased production of matrix metalloproteinases by the synovium is stimulated by pro-inflammatory cytokines, future anti-inflammatory therapies should focus on the synovium as a means of controlling subsequent inflammatory damage.

BAFF from bone marrow-derived mesenchymal stromal cells of rheumatoid arthritis patients improves their B-cell viability-supporting properties

Mesenchymal stromal cells (MSCs) represent a unique cell type with anti-proliferative effects on activated T and B cells. Based on our observation of differences between rheumatoid arthritis and osteoarthritis bone marrow B cells we hypothesized that rheumatoid arthritis bone marrow MSCs may enhance B-cell survival. We aimed to compare the effect of rheumatoid arthritis and osteoarthritis bone marrow-derived MSCs (rheumatoid arthritis MSCs, osteoarthritis MSCs) on the survival of healthy donor purified B cells. Rheumatoid arthritis and osteoarthritis MSCs were isolated from patients undergoing hip replacement surgery, and cultured in vitro for 2-5 passages. Washed cells were co-cultured with CD20+ B cells for 30-90 hours. Cell survival was analysed using 7-amino-actinomycin D labelling by flow cytometry. Expression of mRNA and protein was determined by RT-PCR and flow cytomery. Co-culture with both rheumatoid arthritis MSCs and osteoarthritis MSCs significantly enhanced B-cell survival, the effect being more prominent in rheumatoid arthritis MSCs. Both types of MSCs displayed expression of B cell-activating factor mRNA and protein. Blocking B cell-activating factor signalling from MSCs by specific anti-B cell-activating factor and anti-B cell-activating factor receptor antibodies weakly reversed the effect of MSCs on B-cell survival mainly in rheumatoid arthritis MSCs. MSC interaction with B cells provides stimuli for B-cell survival and therefore may contribute to the pathogenesis of rheumatoid arthritis. MSC-derived factors other than B cell-activating factor are likely to contribute to this effect. This feature is more prominent in rheumatoid arthritis MSCs, possibly due to the B cell-activating factor.

Apolipoprotein A-I and cholesterol in synovial fluid of patients with rheumatoid arthritis, psoriatic arthritis and osteoarthritis

OBJECTIVE

To investigate lipid and apolipoprotein (Apo) levels in synovial fluid (SF) and serum of patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and osteoarthritis (OA).

METHODS

SF of 44 patients (14 RA, 14 PsA, 16 OA) was tested for Apo A-I, HDL-C, total cholesterol (TC), IL-1Beta, TNF-alpha, white blood cell count (WBC) and polymorphonucleate (PMN) percentage. Blood samples, collected simultaneously to the SF, were examined for Apo A-I, HDL-C, TC, TNF-alpha, serum amyloid A (SAA) and C-reactive protein (CRP). Thirty-three healthy donors served as a control group.

RESULTS

Serum levels of Apo A-I, HDL-C and TC were higher in OA as compared with RA, PsA and the control group. The patients with inflammatory arthritis had lower serum levels of Apo A-I and HDL-C than did the controls. Apo A-I concentrations were higher in SF of RA patients, while PsA showed the highest concentration of TC, though not reaching statistical significance. A negative correlation was found between serum Apo A-I and synovial WBC (r=-0.48 p=0.002) and IL-1Beta (r=-0.42 p=0.016). There was a strong positive correlation between the Apo A-I SF/serum ratio and synovial WBC (r=0.73 p<0.001), IL-1Beta (r=0.68 p<0.001) and a weak, yet significant, correlation with serum CRP (r=0.49 p=0.002) and SAA (r=0.41 p=0.008).

CONCLUSION

Our study confirms that in RA Apo A-I and TC levels are decreased in plasma and increased in SF, thus suggesting infiltration of HDL particles in the inflamed joint with inhibition of the local production of proinflammatory cytokines. On the other hand, it can be hypothesized that the sequestration of Apo A-I in the inflamed tissue may, in part, account for the reduction of circulating HDL and the excess cardiovascular risk in RA and PsA patients.

Granzyme B induces apoptosis of chondrocytes with natural killer cell-like cytotoxicity in rheumatoid arthritis

OBJECTIVE

Granzyme B, an apoptosis-inducing factor, is expressed in natural killer (NK) cells, an important factor in innate immunity. We previously reported that granzyme B is expressed in arthritic cartilage and chondrocytes, and suggested that granzyme B expression is related to apoptosis distribution. We have now investigated whether granzyme B directly induces apoptosis in chondrocytes and whether chondrocytes possess NK cell-like function.

METHODS

Chondrocytes included the human C-28/12 chondrocyte cell line, normal chondrocytes, and rheumatoid arthritis (RA) chondrocytes. Apoptosis was analyzed by ELISA and TUNEL after C-28/12 cells were incubated with active granzyme B. NK cell markers were examined in chondrocytes by FACS and immunohistochemistry. Chondrocytes with or without Z-AAD-CMK, a known granzyme B inhibitor, were stimulated with PHA (20 microg/ml), followed by coculture with K562 cells in order to test chondrocyte cytotoxity.

RESULTS

Granzyme B was successfully introduced into C-28/12 chondrocytes, and was confirmed to dose-dependently induce apoptosis. Immunohistochemically, chondrocytes expressed the surface antigens of NK cells and exhibited cytotoxicity against K562 cells, which served as an indicator of cytotoxicity. Z-AAD-CMK inhibited cytotoxicity against K562 cells in a dose-dependent manner, thus confirming that chondrocyte cytotoxicity against K562 cells is dependent on granzyme B.

CONCLUSION

Our findings indicate that chondrocytes possess NK cell-like activity related to innate immunity, and that apoptosis is induced in these cells by granzyme B. Our findings suggest that inflammation activates granzyme B, which participates in the destruction of RA-affected joints.

[The role of anti-cyclic citrullinated peptide (anti-CCP) antibodies in serologic diagnosis and evaluation of disease activity in rheumatoid arthritis]

Anti-cyclic citrullinated peptide (anti-CCP) antibodies are used as highly specific and sensitive markers in the diagnosis of rheumatoid arthritis (RA), in recent years. The aim of this prospective and cross-sectional study was to measure the levels of anti-CCP and rheumatoid factor (RF) in patients with RA and osteoarthritis, and healthy volunteers to evaluate the specificity and possible diagnostic value of anti-CCP and RF, as well as their correlations with parameters of disease activity. Thirty-four patients with RA (mean age: 53.8 +/- 8.6; 29 female), 32 patients with osteoarthritis (mean age: 53.1 +/- 8.1; 26 female) and 32 healthy controls (mean age: 49.6 +/- 6.7; 24 female) were evaluated between July 2004-July 2005. RA diagnosis was done on the basis of criteria recommended by American College of Rheumatology (ACR). Clinical parameters, including disease activity score (DAS28) and health assessment questionnaire (HAQ) indices for physical capacity were detected for RA patients. As a result, 25 (73.5%) of the patients with RA were found positive for anti-CCP (mean value: 74.6 +/- 64.9 RU/ml), while 24 (70.6%) were positive for RF (mean value: 62.6 +/- 84.8 IU/ml). Serum levels of anti-CCP and RF showed statistically significant increase in patients with RA in comparison with osteoarthritis patients (all were negative for anti-CCP; 6.2% were positive for RF) and healthy controls (all were negative for anti-CCP anf RF) (p < 0.001). Twenty-two of the RA patients (64.7%) yielded positive results for both anti-CCP and RF, while seven (20.6%) were negative for both of the parameters. The sensitivity and specificity of anti-CCP reactivity for RA patients diagnosed based on ACR criteria were detected as 73.5% and 100%, respectively; the corresponding results for RF were 70.6% sensitivity and 96.8% specificity. The mean DAS28 and HAQ scores of RA patients with anti-CCP and RF were higher than the patients without anti-CCP and RF, however these differences were not statistically significant (p > 0.05). Furthermore, a correlation between serum anti-CCP levels and HAQ score was determined, while there was no correlation between DAS28 and anti-CCP levels. In conclusion, antibodies against CCP were thought to be more specific than RF for RA, and the determination of anti-CCP in addition to RF could be helpful in serological diagnosis and monitorization of patients with RA.

Involvement of retinoic acid-inducible gene-I in inflammation of rheumatoid fibroblast-like synoviocytes

Interferon (IFN)-gamma is a major cytokine that regulates T helper 1-type immune reactions and serves as an important mediator in the pathogenesis of autoimmune diseases. Retinoic acid-inducible gene-I (RIG-I) is an IFN-gamma-inducible gene and known to be involved in the inflammatory and immune reactions. In the present study, we found high levels of RIG-I expression in synovial tissues of rheumatoid arthritis (RA), while the expression in osteoarthritis tissues was low. Treatment of cultured fibroblast-like synoviocytes with IFN-gamma markedly induced the expression of RIG-I. Knockdown of RIG-I in fibroblast-like synoviocytes, with specific siRNA, resulted in the inhibition of the IFN-gamma-induced expression of chemokine (C-X-C motif) ligand 10 (CXCL10)/IFN-gamma-inducible protein-10 (IP-10), a chemokine with chemotactic activity towards T cells. These findings suggest that RIG-I may play an important role in the pathogenesis of synovial inflammation in RA, at least in part, by regulating the IFN-gamma-induced expression of CXCL10/IP-10.

High levels of serum IL-18 promote cartilage loss through suppression of aggrecan synthesis

Osteoarthritis (OA) is closely related to the function of several inflammatory cytokines. It has been reported that older age is associated with higher serum levels of the inflammatory cytokine IL-18. In the present study, we investigated the long-term role of serum IL-18 in cartilage loss in vivo using a new strain of IL-18 transgenic mouse (Tg) in comparison with wild-type (WT) mice. The IL-18 Tg mouse strain we developed constitutively overproduces soluble mature IL-18 in the lungs but not in other tissues, including joints. These Tg mice showed high levels of serum IL-18, but not IL-1beta. No inflammatory cells, fibrillation or synovitis were observed in the knee joints of either IL-18 Tg or WT mice. However, the cartilage cellularity of the femoral and tibial condyles of IL-18 Tg mice was significantly reduced in comparison with control WT mice. Aggrecan was detected in only a few cells in the deep zone of the articular cartilage of Tg mice. The expression of aggrecan mRNA was also significantly decreased in articular chondrocytes from Tg mice when compared with WT mice. In contrast, endogenous IL-18 mRNA was significantly increased in the chondrocytes of Tg mice in comparison with WT mice. Expression of IFN-gamma was also significantly increased in the Tg mice. Moreover, IL-18 transgene-positive caspase-1-deficient mice showed articular cartilage loss that was independent of endogenous IL-1beta. In cultured chondrocytes isolated from WT mice, the expression of aggrecan mRNA was dosage-dependently suppressed by treatment with recombinant IL-18. In contrast, IL-18 stimulated the expression of mRNA for endogenous IL-18 and IFN-gamma. These results suggest that high levels of serum IL-18 promote the overexpression of endogenous IL-18 in articular chondrocytes, resulting in cartilage loss through suppression of aggrecan synthesis. Thus IL-18 may play an important role in the pathogenesis of articular cartilage loss in osteoarthritis.

Interleukin 17 levels are increased in juvenile idiopathic arthritis synovial fluid and induce synovial fibroblasts to produce proinflammatory cytokines and matrix metalloproteinases

OBJECTIVE

Cytokines are the major mediators of joint damage in chronic arthritis. Data on synovial fluid (SF) concentration of Th17 cell-derived cytokine interleukin 17 (IL-17) in patients with juvenile idiopathic arthritis (JIA) are sparse. We measured levels of IL-17 in SF specimens from children with enthesitis-related arthritis (ERA) and polyarticular JIA (poly-JIA), and studied the ability of IL-17 to produce matrix metalloproteinases (MMP) and cytokines by fibroblast-like synoviocytes (FLS) from patients with ERA.

METHODS

IL-17 levels were measured in SF of patients with ERA (n = 43), poly-JIA (n = 17), rheumatoid arthritis (RA; n = 35), and osteoarthritis (OA; n = 10) by ELISA. In patients with JIA, 10 paired serum samples were also assayed. FLS were cultured from SF of patients with ERA and subsequently stimulated for 48 h by IL-17 or tumor necrosis factor-alpha. Later the production of IL-6, IL-8, MMP-1, MMP-3, and tissue inhibitor of metalloproteinase (TIMP)-1 was measured in the culture supernatants by ELISA.

RESULTS

Median IL-17 levels in SF were higher in patients with JIA [28 pg/ml (range 0-200)] compared to OA [0 pg/ml (range 0-84); p < 0.001] and RA (p < 0.05). The levels were comparable between poly-JIA patients and the ERA group. The median SF IL-17 levels were significantly higher compared to serum levels in children with JIA (p < 0.005). In ERA, SF IL-17 correlated with number of swollen joints (r = 0.35; p < 0.05), number of joints with limited mobility (r = 0.55; p < 0.001), and number of tender joints (r = 0.46; p < 0.01); however, no correlation was seen with erythrocyte sedimentation rate. IL-17 induced FLS to produce IL-6, IL-8, MMP-3, and MMP-1. However, there was no effect on the production of TIMP.

CONCLUSION

Increased IL-17 levels in ERA SF correlate with disease activity and this may be due to increased production of MMP and cytokines by IL-17.

Osteoarthritis: a tale of three tissues

While research in osteoarthritis has focused on the events that lead to the destruction of articular cartilage, recent evidence suggests that two other components of the joints-bone and synovium-also play key roles in pathogenesis. All three tissues undergo alterations in concert at the structural levels in response to mechanical stress and joint malalignment. Advanced imaging studies such as MRI support this interdependence, revealing the classical changes of joint space narrowing and cartilage degeneration as well as the more recently appreciated bone marrow lesions and synovitis that may correlate with clinical symptoms. Molecular evidence also points to a coordinated release of cytokines and other inflammatory mediators from each of the three tissues together in progression of disease, although we are still in search of biochemical signatures that will predict the subset of patients who progress more quickly-and who will provide key clues to successful molecular targets in future therapies. At this time we lack definitive evidence pointing to which, if any, of the three tissues should serve as the main target for disease modification or structure protection, although most efforts have focused on cartilage. Thus current therapies focus on controlling symptoms, while research efforts search for reliable imaging and molecular biomarkers to help guide future trials of potential disease-modifying agents.