Predicting joint damage in rheumatoid arthritis using MRI scanning

Predicting prognosis in the patient with newly diagnosed rheumatoid arthritis is of key importance so that high-cost therapies can be tailored to the needs of the individual. In a recent issue of Arthritis Research and Therapy, the prognostic significance of MRI changes at the forefoot has been studied. While progression to radiographic erosion occurred rarely in this group of patients exposed to potent disease-suppressing therapies, including TNF inhibitors, MRI bone edema, representing osteitis, has been further implicated as a forerunner to bone erosion. Early MRI scans of the forefoot were helpful in defining those with the potential to progress as well as those in a good prognosis category.     

Inflammatory cells and bone loss in rheumatoid arthritis

Pathogenic bone erosion is often associated with inflammation. The destructive bone erosion that is often seen in rheumatoid arthritis is probably due to the close proximity of inflamed tissues to bone. Over the past decade, major advances have been made in our understanding of the factors that are crucial in regulating osteoclast bone resorption. It is not surprising that these factors are expressed by inflammatory cells that are present in the rheumatoid joint. It now appears that we can add neutrophils to the list of inflammatory cells found in the inflamed rheumatoid joint that express factors that regulate bone erosion.     

Breakdown of cartilage proteoglycan in a tissue culture model of rheumatoid arthritis

Proteoglycan breakdown was studied in a coculture model which mimics the confrontation between synovium and cartilage that occurs in rheumatoid arthritis. Bovine nasal-septum cartilage discs radioactively labeled (³⁵SO₄^2? with or without [³H]glucosamine) and ‘chased’ in non-radioactive medium were cultured in contact with minced rheumatoid synovial membranes for intervals up to 8 days. Synovium-stimulated (2–3 fold) cartilage breakdown was unaffected by ascorbate supplementation. Labeled products (small molecules plus proteoglycan complexes) in culture media were characterized by chromatographic, sedimentation and enzymic digestion methods. Breakdown was dominated by the release of a range of proteoglycan products, fully disaggregated and incapable of reaggregation with added hyaluronate. Because constituent glycosaminoglycans were of uniform size, proteoglycan polydispersity was attributed to differences in core protein length. Hydrocortisone inhibited degradation and partially prevented the shift of proteoglycans to lower average molecular weight. An additional breakdown pattern occasionally noted during the initial 48 h of coculture was characterized by release of a subpopulation of low charge-density proteoglycan bearing shortened glycosaminoglycan chains, consistent with glycosidase action. We conclude that rheumatoid synovia exhibit two distinct cartilage degradative potencies in vitro that may be important in vivo: (a) A variable hyaluronidase-like activity at early culture times, and (b) a dominant proteolytic activity generating an array of disaggregated proteoglycann products that differ largely on the basis of their core lengths. The response to hydrocortisone is consistent with inhibition of proteolysis through the stabilization of cellular membranes.     

Treatment with recombinant interferon-beta reduces inflammation and slows cartilage destruction in the collagen-induced arthritis model of rheumatoid arthritis

We investigated the therapeutic potential and mechanism of action of IFN-beta protein for the treatment of rheumatoid arthritis (RA). Collagen-induced arthritis was induced in DBA/1 mice. At the first clinical sign of disease, mice were given daily injections of recombinant mouse IFN-beta or saline for 7 days. Disease progression was monitored by visual clinical scoring and measurement of paw swelling. Inflammation and joint destruction were assessed histologically 8 days after the onset of arthritis. Proteoglycan depletion was determined by safranin O staining. Expression of cytokines, receptor activator of NF-kappaB ligand, and c-Fos was evaluated immunohistochemically. The IL-1-induced expression of IL-6, IL-8, and granulocyte/macrophage-colony-stimulating factor (GM-CSF) was studied by ELISA in supernatant of RA and osteoarthritis fibroblast-like synoviocytes incubated with IFN-beta. We also examined the effect of IFN-beta on NF-kappaB activity. IFN-beta, at 0.25 microg/injection and higher, significantly reduced disease severity in two experiments, each using 8-10 mice per treatment group. IFN-beta-treated animals displayed significantly less cartilage and bone destruction than controls, paralleled by a decreased number of positive cells of two gene products required for osteoclastogenesis, receptor activator of NF-kappaB ligand and c-Fos. Tumor necrosis factor alpha and IL-6 expression were significantly reduced, while IL-10 production was increased after IFN-beta treatment. IFN-beta reduced expression of IL-6, IL-8, and GM-CSF in RA and osteoarthritis fibroblast-like synoviocytes, correlating with reduced NF-kappaB activity. The data support the view that IFN-beta is a potential therapy for RA that might help to diminish both joint inflammation and destruction by cytokine modulation.     

Clinically translatable cell tracking and quantification by MRI in cartilage repair using superparamagnetic iron oxides

BACKGROUND: Articular cartilage has very limited intrinsic regenerative capacity, making cell-based therapy a tempting approach for cartilage repair. Cell tracking can be a major step towards unraveling and improving the repair process of these therapies. We studied superparamagnetic iron oxides (SPIO) for labeling human bone marrow-derived mesenchymal stem cells (hBMSCs) regarding effectivity, cell viability, long term metabolic cell activity, chondrogenic differentiation and hBMSC secretion profile. We additionally examined the capacity of synovial cells to endocytose SPIO from dead, labeled cells, together with the use of magnetic resonance imaging (MRI) for intra-articular visualization and quantification of SPIO labeled cells. METHODOLOGY/PRINICIPAL FINDINGS: Efficacy and various safety aspects of SPIO cell labeling were determined using appropriate assays. Synovial SPIO re-uptake was investigated in vitro by co-labeling cells with SPIO and green fluorescent protein (GFP). MRI experiments were performed on a clinical 3.0T MRI scanner. Two cell-based cartilage repair techniques were mimicked for evaluating MRI traceability of labeled cells: intra-articular cell injection and cell implantation in cartilage defects. Cells were applied ex vivo or in vitro in an intra-articular environment and immediately scanned. SPIO labeling was effective and did not impair any of the studied safety aspects, including hBMSC secretion profile. SPIO from dead, labeled cells could be taken up by synovial cells. Both injected and implanted SPIO-labeled cells could accurately be visualized by MRI in a clinically relevant sized joint model using clinically applied cell doses. Finally, we quantified the amount of labeled cells seeded in cartilage defects using MR-based relaxometry. CONCLUSIONS: SPIO labeling appears to be safe without influencing cell behavior. SPIO labeled cells can be visualized in an intra-articular environment and quantified when seeded in cartilage defects.     

Rationale of using different biological therapies in rheumatoid arthritis

Due to ongoing developments of novel agents in the field of biological pharmacotherapy, there are now more arrows available in clinicians' quivers for the treatment of rheumatic conditions. As a consequence, however, clear treatment strategies have to be defined in order to guarantee a qualitatively high and individually stage-adapted, state-of-the-art regimen for affected patients. This review summarizes recent evidence regarding the rationale of using different biological therapies to treat rheumatoid arthritis, the most common inflammatory joint disorder after activated osteoarthritis, and draws an actual picture of a possible standardized therapeutic algorithm without claiming exclusive appropriateness.     

Gene expression and activity of cartilage degrading glycosidases in human rheumatoid arthritis and osteoarthritis synovial fibroblasts

Introduction

Similar to matrix metalloproteinases, glycosidases also play a major role in cartilage degradation. Carbohydrate cleavage products, generated by these latter enzymes, are released from degrading cartilage during arthritis. Some of the cleavage products (such as hyaluronate oligosaccharides) have been shown to bind to Toll-like receptors and provide endogenous danger signals, while others (like N-acetyl glucosamine) are reported to have chondroprotective functions. In the current study for the first time we systematically investigated the expression of glycosidases within the joints.

Methods

Expressions of β-D-hexosaminidase, β-D-glucuronidase, hyaluronidase, sperm adhesion molecule 1 and klotho genes were measured in synovial fibroblasts and synovial membrane samples of patients with rheumatoid arthritis and osteoarthritis by real-time PCR. β-D-Glucuronidase, β-D-glucosaminidase and β-D-galactosaminidase activities were characterized using chromogenic or fluorogenic substrates. Synovial fibroblast-derived microvesicles were also tested for glycosidase activity.

Results

According to our data, β-D-hexosaminidase, β-D-glucuronidase, hyaluronidase, and klotho are expressed in the synovial membrane. Hexosaminidase is the major glycosidase expressed within the joints, and it is primarily produced by synovial fibroblasts. HexA subunit gene, one of the two genes encoding for the alpha or the beta chains of hexosaminidase, was characterized by the strongest gene expression. It was followed by the expression of HexB subunit gene and the β-D-glucuronidase gene, while the expression of hyaluronidase-1 gene and the klotho gene was rather low in both synovial fibroblasts and synovial membrane samples. Tumor growth factor-β1 profoundly downregulated glycosidase expression in both rheumatoid arthritis and osteoarthritis derived synovial fibroblasts. In addition, expression of cartilage-degrading glycosidases was moderately downregulated by proinflammatory cytokines including TNFα, IL-1β and IL-17.

Conclusions

According to our present data, glycosidases expressed by synovial membranes and synovial fibroblasts are under negative regulation by some locally expressed cytokines both in rheumatoid arthritis and osteoarthritis. This does not exclude the possibility that these enzymes may contribute significantly to cartilage degradation in both joint diseases if acting in collaboration with the differentially upregulated proteases to deplete cartilage in glycosaminoglycans.     

Monitoring cartilage loss in the hands and wrists in rheumatoid arthritis with magnetic resonance imaging in a multi-center clinical trial: IMPRESS (NCT00425932)

Introduction

Magnetic resonance imaging (MRI) is increasingly being used in clinical trials of rheumatoid arthritis (RA) because of its superiority over x-ray radiography (XR) in detecting and monitoring change in bone erosion, osteitis and synovitis. However, in contrast to XR, the MRI scoring method that was used in most clinical trials did not include cartilage loss. This limitation has been an obstacle to accepting MRI as a potential alternative to XR in clinical trials. Cross-sectional studies have shown MRI to be sensitive for cartilage loss in the hands and wrist; although, longitudinal sensitivity to change has not yet been confirmed. In this study we examined the ability of MRI to monitor change in cartilage loss in patients with RA in a multi-site clinical trial setting.

Methods

Thirty-one active RA patients from a clinical trial (IMPRESS) who were randomized equally into treatment with either rituximab + methotrexate or placebo + methotrexate had MRI of the dominant hand/wrist at baseline, 12 weeks and 24 weeks at 3 clinical sites in the US. Twenty-seven of these patients also had XR of both hands/wrists and both feet at baseline and 24 weeks. One radiologist scored all XR images using the van der Heijde-modified Sharp method blinded to visit order. The same radiologist scored MR images for cartilage loss using a previously validated 9-point scale, and bone erosion using the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA MRI Score (RAMRIS) blinded to visit order and XR scores. Data from the two treatment arms were pooled for this analysis.

Results

Mean MRI cartilage score increased at 12 and 24 weeks, and reached statistical significance at 24 weeks. XR total Sharp score, XR erosion score and XR joint-space narrowing (JSN) score all increased at 24 weeks, but only XR total Sharp score increased significantly.

Conclusions

To our knowledge, this is the first publication of a study demonstrating MRI''s ability to monitor cartilage loss in a multi-site clinical trial. Combined with MRI''s established performance in monitoring bone erosions in RA, these findings suggest that MRI may offer a superior alternative to XR in multi-site clinical trials of RA.     

Bone loss: Quantitative imaging techniques for assessing bone mass in rheumatoid arthritis

Osteoporosis is associated with low bone mass and microarchitectural deterioration of bone tissue with clinical manifestation of low trauma fractures. Rheumatoid arthritis (RA) is a risk factor due to generalized and articular bone loss. This minireview presents past and current bone mass measurement techniques in RA. These techniques include: plain radiographs, absorptiometry, quantitative computed tomography (QCT) and ultrasound. The most widely used technique is dual x-ray absorptiometry (DXA). RA patients have lower bone mass as compared with normals and substantial bone loss may occur early after the onset of disease. Measurement of bone mineral density (BMD) at the hand using either DXA or ultrasound maybe a useful tool in the management of RA patients.     

Localization of MHC class II/human cartilage glycoprotein-39 complexes in synovia of rheumatoid arthritis patients using complex-specific monoclonal antibodies

Recently human cartilage gp-39 (HC gp-39) was identified as a candidate autoantigen in rheumatoid arthritis (RA). To further investigate the relevance of this Ag in RA, we have generated a set of five mAbs to a combination epitope of complexes of HC gp-39(263-275) and the RA-associated DR alpha beta 1*0401 HLA class II molecules. FACS studies revealed that these mAb recognize specific complexes on homozygous DR alpha beta 1*0401-positive B lymphoblastoid cells pulsed with HC gp-39(263-275). The best mAb, 12A, was further characterized using a set of irrelevant DR alpha beta 1*0401-binding peptides and truncated/elongated versions of HC gp-39(263-275) itself. The minimal epitope recognized in combination with DR alpha beta 1*0401 was HC gp-39(263-273). Peptides not encompassing HC gp-39(263-273) were not recognized. Three of five mAb were able to inhibit (up to 90%) the response of HC gp-39(263-275)-specific DR alpha beta 1*0401-restricted T cell hybridomas to peptide-pulsed APC or purified complexes. Using mAb 12A, we have been able to identify and localize dendritic cells that present DR alpha beta 1*0401/HC gp-39(263-275) complexes in synovial tissue of DR alpha beta 1*0401-positive RA patients, indicating local presentation of the HC gp-39(263-275) epitope in the inflamed target tissue by professional APC. These data support a role of HC gp-39 in the local autoimmune response that leads to chronic inflammation and joint destruction.     

Bone loss. Quantitative imaging techniques for assessing bone mass in rheumatoid arthritis

Osteoporosis is associated with low bone mass and microarchitectural deterioration of bone tissue with clinical manifestation of low trauma fractures. Rheumatoid arthritis (RA) is a risk factor due to generalized and articular bone loss. This minireview presents past and current bone mass measurement techniques in RA. These techniques include: plain radiographs, absorptiometry, quantitative computed tomography (QCT) and ultrasound. The most widely used technique is dual x-ray absorptiometry (DXA). RA patients have lower bone mass as compared with normals and substantial bone loss may occur early after the onset of disease. Measurement of bone mineral density (BMD) at the hand using either DXA or ultrasound maybe a useful tool in the management of RA patients.     

Role of microRNA-26a in cartilage injury and chondrocyte proliferation and apoptosis in rheumatoid arthritis rats by regulating expression of CTGF

This study is carried out to investigate the role of microRNA-26a (miR-26a) in cartilage injury and chondrocyte proliferation and apoptosis in rats with rheumatoid arthritis (RA) by regulating expression of CTGF. A rat model of RA induced by type II collagen was established. The rats were assigned into normal, RA, RA + mimics negative control (NC), and RA + miR-26a mimics groups, and the cells were classified into blank, mimics NC, and miR-26a mimics groups. The degree of secondary joint swelling and arthritis index, expression of miR-26a, pathological changes, proliferation and apoptosis of chondrocytes, and expression of CTGF, interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α, Bax, and Bcl-2 were also determined through a series of experiments. The targeting relationship between miR-26a and CTGF was verified. Initially, downregulated miR-26a was found in cartilage tissues and inflammatory articular chondrocytes of RA rats. In addition, CTGF was determined as a direct target gene of miR-26a, and upregulation of miR-26a inhibited CTGF expression in cartilage tissues of RA rats. Furthermore, upregulation of miR-26a reduced swelling and inflammation of joints, inhibited cartilage damage, apoptosis of chondrocytes, inflammatory injury, promotes proliferation, and inhibited apoptosis of inflammatory articular chondrocytes, which may be correlated with the targeting inhibition of CTGF expression. Collectively, the results demonstrate that upregulating the expression of miR-26a could attenuate cartilage injury, stimulate the proliferation, and inhibit apoptosis of chondrocytes in RA rats.     

A tissue-culture model of cartilage breakdown in rheumatoid arthritis. Quantitative aspects of proteoglycan release

1. The destruction of articular cartilage in human rheumatoid and other arthritides is the result of diverse mechanical, inflammatory and local cellular factors. A tissue-culture model for studying cartilage-synovial interactions that may be involved in the final common pathway of joint destruction is described. 2. Matrix breakdown was studied in vitro by using bovine nasal-cartilage discs cultivated in contact with synovium. Synovia were obtained from human and animal sources. Human tissue came from patients with ;classical' rheumatoid arthritis, and animal tissue from rabbits with antigen-induced arthritis. 3. Cartilage discs increased their proteoglycan content 2-3-fold during 8 days in culture. Proteoglycan was also released into culture medium, approx. 70% arising from cartilage breakdown. 4. Synovial explants from human rheumatoid and rabbit antigen-induced arthritis produced equivalent stimulation of proteoglycan release. After an initial lag phase, the breakdown rate rose abruptly to a maximum, resulting in a 2-fold increase of proteoglycan accumulation in culture medium after 8-10 days. 5. High-molecular-weight products shed into culture media were characterized chromatographically and by differential enzymic digestion. Proteoglycan-chondroitin sulphate accounted for 90% of the released polyanion, and its partial degradation in the presence of synovial explants was consistent with limited proteolytic cleavage. 6. Rheumatoid synovium applied to dead cartilage increased the basal rate of proteoglycan release. Living cartilage was capable of more extensive autolysis, even in the absence of synovium. However, optimal proteoglycan release required the interaction of living synovium with live cartilage. These findings support the view that a significant component of cartilage breakdown may be chondrocyte-mediated.     

Analysis of agalacto-IgG in rheumatoid arthritis using surface plasmon resonance

It is well established that IgG from rheumatoid arthritis (RA) patients are less galactosylated than IgG from normal individuals. Determination of agalacto-IgG may therefore aid in diagnosis and treatment of RA. The decrease in galactosylation of IgG leads to an increase in terminal N-acetylglucosamine residues, which can be detected using a specific lectin from Psathyrella velutina. In the present study IgG from RA and control serum was purified using affinity chromatography. The samples were then, after reduction, analyzed on a BIOCORE® 2000 system with immobilized Psathyrella velutina lectin. Using this technique it was possible to discriminate between IgG from RA patients and IgG from control individuals with respect to its content of IgG with terminal N-acetylglucosamine. The affinity biosensor technique makes it possible to detect binding without labeling or using secondary antibodies.