Dendritic cells in rheumatoid synovial membrane after total removal of the hyaline articular cartilage

OBJECTIVE: To investigate the effect of total removal of the hyaline articular cartilage on dendritic cells in synovial membrane in rheumatoid arthritis (RA) or ankylosing spondylitis (AS). PATIENTS AND METHODS: Immunohistochemical staining for two dendritic cell markers, CD35 and RFD1, was carried out on synovial membrane specimens from arthritis patients undergoing primary (n=10) or revision (n=8) total hip replacement (THR). The results are expressed as the number (mean+/-standard deviation) of positive cells per 1000 total cells. RESULTS: CD35-(112+/-9) and RFD1-(27+/-5) positive cells were found in all primary RA synovial membrane, while only two out of eight synovial membrane samples from revision THR contained CD35-positive follicular dendritic cells (nine and 12 cells), and no revision samples contained any RFD1-positive interdigitating dendritic cells. CONCLUSION: Removal of the hyaline articular cartilage reduces the infiltration and functional differentiation of dendritic cells in synovial membrane. Our findings suggest that the antigen driving chronic arthritis/synovitis is contained in the hyaline articular cartilage.     

Removal of hyaline articular cartilage reduces lymphocyte infiltration and activation in rheumatoid synovial membrane.

OBJECTIVE: To analyze the effect of removal of hyaline articular cartilage on synovial membrane pathology in chronic arthritis. METHODS: Synovial membrane samples were obtained from patients with rheumatoid arthritis or ankylosing spondylitis in association with total hip arthroplasty, either primary or revision surgery. Synovial membrane histopathology was assessed by immunochemical staining and morphometry. RESULTS: CD68 positive macrophages were common in revision synovial membranes. In contrast, T lymphocytes were much more common in primary rheumatoid synovial membranes (p < 0.001). Many T lymphocytes in primary synovial membrane were HLA-D/DR positive (p < 0.001) and interleukin 2 receptor (IL-2R) positive (p < 0.001) and contained interferon-gamma(IFN-gamma; p < 0.001) and tumor necrosis factor-beta (TNF-beta; p < 0.001). In contrast, revision synovial membranes from patients with chronic arthritis contained only a few HLA-D/DR positive T cells and practically no IL-2R, IFN-gamma, or TNF-beta positive activated T lymphocytes. CONCLUSION: The components of hyaline articular cartilage may be the source of autoantigen responsible for perpetuation of chronic arthritides.     

Cartilage oligomeric matrix protein (COMP) is modified by intra-articular liposomal clodronate in an experimental model of arthritis

OBJECTIVE: High-dose liposomal bisphosphonates exert apoptotic effects. This work studies the chondroprotective and anti-inflammatory properties of intra-articularly administered low-dose, non-cytotoxic liposomal clodronate. METHODS: Antigen induced arthritis in rabbits was treated with intra-articular injections of liposomal clodronate. Drug effects on cartilage oligomeric matrix protein COMP was assessed using immunohistochemistry and morphometry of synovial membrane and hyaline articular cartilage. RESULTS: COMP remained close to normal in liposomal clodronate treated superficial articular cartilage compared to a significant loss of COMP in arthritis controls treated with empty liposomes. The middle and deep layers of the hyaline articular cartilage were characterized by highly increased COMP expression in liposomal clodronate treated AIA joints compared to controls. In contrast to cartilage, synovial COMP expression was slightly decreased as a result of liposomal clodronate treatment. CONCLUSION: Low-dose, non-cytotoxic liposomal clodronate exerts a dichotomous effect on synovial membrane and articular cartilage COMP in the AIA model. COMP is a useful inflammation marker in the synovial tissue, but it also contributes to the structural integrity of the hyaline articular cartilage forming bridges between type II and IX collagens. Enhancement of COMP in clodronate treated AIA cartilage suggests a chondroprotective and anti-inflammatory effect in the inflammatorily damaged and mechanically strained cartilage.     

The nature and designation of osteoarthritis determined by its histopathology

Specimens of synovial tissue and articular cartilage removed at operations of patients with primary degenerative joint disease were scrutinized for defined histopathological parameters. The findings in the synovial membrane were subsequently compared as to frequency and intensity with identical parameters ascertained in specimens removed from patients with definite rheumatoid arthritis. These examinations disclosed the presence of synovial inflammatory features, although at lesser incidence and intensity than in rheumatoid arthritis; therefore the designation of arthritis is indicated. On the basis of the concurrently examined tissue specimens of the articular cartilage, and in consensus with the generally acknowledged start of the degenerative joint disease by disintegrating changes in the articular cartilage, the prefix of chondrosis is appropriate.     

Morphological features of articular cartilage and synovial membrane in osteoarthritis and rheumatoid arthritis

Osteoarthritis (OA) and rheumatoid arthritis (RA) do not show any specific morphological findings. However, there are many morphological findings which are common to each disease. In the current study, we describe morphological changes of articular cartilage and synovial membrane during progression of joint destruction in OA and RA, respectively.     

Therapeutic effects on cartilage metabolism in arthritis as measured by release of proteoglycan structures into the synovial fluid.

Proteoglycans are molecules that are degraded and released from the articular cartilage into the synovial fluid early in an arthritic process. Such released proteoglycans were quantified by an enzyme linked immunosorbent assay (ELISA). The proteoglycan content in synovial fluid from patients with various knee joint arthritides was constant in two samples withdrawn five days apart. To determine if therapeutic measures were paralleled by effects directly on the articular cartilage the patients were treated with local injections of glucocorticoids. In all patients the glucocorticoids induced a reduction of the proteoglycan content in the synovial fluid, reflecting their effects on the cartilage. In two patients with spontaneous remission of their arthritis a reduction in the proteoglycan content in the synovial fluid was also noted. The quantification of proteoglycans in synovial fluid appears to have potential as a useful tool for monitoring the effects of therapy on cartilage metabolism.     

Synthesis of arachidonate oxidation products by synovial joint tissues during the development of chronic erosive arthritis

An animal model, antigen-induced arthritis in the rabbit, was used to investigate the synthesis of arachidonic acid oxidation products (eicosanoids) by tissues of the knee joints during the initiation and early phase of this developing chronic destructive lesion. High concentrations of immunoreactive prostaglandin E2 and immunoreactive leukotriene B4 were found to be present in the synovial fluid in the early lesion. These levels rapidly declined, as did the ability of the infiltrating cells of the arthritic joint fluids to synthesize leukotriene B4. Articular cartilage and synovial lining were maintained for 24 hours in nonproliferative organ culture, and the synthesis of eicosanoids was measured by assay of the culture fluids. The synovial lining was the major source of eicosanoids. Synthesis of prostaglandin E2, prostacyclin, thromboxane A2, and leukotriene B4 by the arthritic synovial lining was low during the first few days, but reached maximal values between day 5 and day 15 of disease duration. Maximal eicosanoid production occurred around the time that damage to articular cartilage and bone has been reported to occur, though it is not certain that these two events are linked. It was demonstrated that, in chronic lesions, the arthritic synovial lining was still producing elevated levels of eicosanoids compared with levels in the control tissue.     

Intrasynovial levels of sulphated glycosaminoglycans and autoantibodies to type II collagen in rheumatoid arthritis: a correlative analysis

Summary It is uncertain whether the autoantibodies to type II collagen that occur frequently in the serum and synovial fluid of patients with rheumatoid arthritis (RA), but rarely in other articular diseases, are primary or secondary to cartilage damage. Hence, we measured antibodies in synovial fluid from patients with RA and other articular disease and related these to the concentration of sulphated glycosaminoglycans, as a measure of ongoing cartilage catabolism. Synovial fluids from 42 patients with RA and 30 patients with other articular diseases were studied. We found that levels of antibodies to native and denatured collagen were significantly higher in RA than in all other articular diseases, whereas concentrations of sulphated glycosaminoglycans were similar. The absence of any correlation between levels of sulphated glycosaminoglycans and antibodies to collagen weighs against the occurrence of such antibodies in RA as a secondary effect of cartilage damage.     

Carrageenin-induced arthritis: V. A morphologic study of the development of inflammation in acute arthritis

Following a single injection of the polysaccharide carrageenin into the rabbit knee joint, a rapid inflammatory process occurs in the joint space and synovial membrane, followed by changes in the articular cartilage. Initially there is an influx of cells, mainly PMNs, into the synovial fluid, accompanied by proliferation of the synovial lining cells and infiltration of the synovial membrane. The numbers of synovial fluid cells decline gradually after 24 hr. The reaction in the synovial membrane is greatest at day 7, and inflammation is still evident at day 21. Initially, the infiltrate consists mainly of PMNs, but by day 7 it is predominantly mononuclear, with small clusters of lymphocytes.The articular cartilage shows loss of metachromasia with toluidine blue at 3–14 days after injection, but stains normally after day 21. Electron microscopy shows damage to the chondrocytes at days 1 and 7, with complete destruction of cells in the surface layer. At day 7 cells in the deeper layers have lost the apparatus required for proteoglycan synthesis, but at day 21 the cells appear virtually normal.There was no evidence for a direct inhibitory effect of carrageenin on proteoglycan biosynthesis. Most labeled carrageenin was rapidly cleared from the joint space, but about 10% was retained in the synovial membrane and 0.6% in articular cartilage at 48 hr after injection.Since the increase and decline in PMN numbers respectively precede the cartilage damage and recovery, it is suggested that there may be a correlation between the clinical activity of arthritis and the number of PMNs in the synovial fluid.     

Lectin-like oxidized low-density lipoprotein receptor 1 mediates leukocyte infiltration and articular cartilage destruction in rat zymosan-induced arthritis

OBJECTIVE: The relationship between rheumatoid arthritis and atherosclerosis has been recognized for >20 years. This study aimed to elucidate the roles of oxidized low-density lipoprotein (ox-LDL; one of the main pathogenic factors of atherosclerosis) and its endothelial receptor, lectin-like ox-LDL receptor 1 (LOX-1), in arthritic joints using a rat zymosan-induced arthritis (ZIA) model. METHODS: LOX-1 expression and ox-LDL accumulation in arthritic joints were detected by immunohistochemistry using specific mouse anti-LOX-1 and anti-ox-LDL monoclonal antibodies, respectively. To elucidate the effects of the expressed LOX-1 on arthritis, ZIA rats were treated with anti-LOX-1 antibody or normal mouse IgG. The severity of arthritis was analyzed by joint swelling. Cell infiltration, synovial hyperplasia, and proteoglycan losses were also determined by histologic scoring. Proinflammatory cytokine and nitrite levels in serum and joint fluid were also measured. RESULTS: Immunohistochemical study of ZIA demonstrated LOX-1 expression on synovial endothelium and postcapillary venules at 6 hours after the induction of inflammation, with maximum expression detected at 24 hours. LOX-1 was also expressed weakly on both joint cartilage and synovium. Ox-LDL, a ligand of LOX-1, was also detected in articular chondrocytes. Administration of anti-LOX-1 antibody, which blocks LOX-1 activity, suppressed joint swelling (by 33.5%), leukocyte infiltration, and joint nitrite accumulation at 24 hours, as well as cartilage destruction at 7 days, compared with control rats. CONCLUSION: LOX-1 induction in arthritic joints might play a role in promoting joint inflammation and cartilage destruction by mediating leukocyte infiltration into the arthritic joints of ZIA rats.     

Subtyping of osteoarthritic synoviopathy

OBJECTIVE: Osteoarthritis research is traditionally concentrating on events within the degenerated articular cartilage. Changes in the synovial membrane are largely neglected. In fact, they are generally interpreted as secondary to the cartilage changes and not pathogenetically involved in the disease process. In this study, we present a systematic analysis of the synovial reaction pattern in early and late stages of the osteoarthritic disease process. METHODS: A large series of synovial specimens derived from early and late stage osteoarthritic cartilage disease were investigated by histological and immunohistochemical means for tissue architecture and inflammatory cell infiltrates. For comparison, also samples with rheumatoid arthritis, seronegative arthritis, and septic arthritis were included as well as normal synovial membrane specimens. RESULTS: In all specimens derived from patients with diagnosed osteoarthritis alterations of the synovial tissue were observed. A large spectrum of alterations was found in different stages of osteoarthritic joint disease and four different basic pattern of synovial reactions could be identified: (i) hyperplastic, (ii) inflammatory, (iii) fibrotic, and (iv) detritus-rich synoviopathy. CONCLUSION: We show that in all cases of clinically overt osteoarthritic joint disease significant synovial pathology is associated. Furthermore, our study clearly documents that in osteoarthritic synovium significant inflammation can occur. This is suggestive of a distinct pathogenetic role of the synovium also in osteoarthritic cartilage degeneration at least in a subset of cases.     

Calcium pyrophosphate dihydrate and basic calcium phosphate crystalinduced arthropathies: Update on pathogenesis,clinical features,and Therapy

Calcium-containing crystals are the most common class for the osteoarthritic joint. They are responsible for acute periarthritis and destructive arthropathies, and for tissue deposits mimicking tumor-like masses. These crystals encompassed mainly calcium pyrophosphate dihydrate and basic calcium phosphate crystals, with the latter being related to hydroxyapatite, carbonate-substituted apatite, and octacalcium phosphate. Calcification deposit mechanisms will be reviewed with respect to extracellular inorganic pyrophosphate dysregulation mainly caused by modulation of specific membrane channel disorders. Genetic defects have been extensively studied and identified mutation of specific genes such as ANKH and COL. Pathogenesis of crystal-induced inflammation is related to synovial tissue and direct cartilage activation. Besides classical knee or wrist pseudogout attacks or Milwaukee shoulder arthropathies, clinicians should be aware of other specific common presentations, such as erosive calcifications, spinal cord compression by intraspinal masses, ligamentum flavum calcification, or atypical calcified tophus. Promising clinical results for preventing calcium crystal deposits and cartilage degradation are lacking. Practical imaging tools are needed to monitor reduction of calcification of fibrocartilage and articular cartilage as markers of drug efficacy.     

Identification of immunoglobulins and complement in rheumatoid articular collagenous tissues

Ninety-three patients with a variety of joint diseases were studied for evidence of immune complexes in articular collagenous tissues. Frozen sections of freshly obtained biopsies of hyaline articular cartilage and menisci were stained with fluoresceinated monospecific antisera for evidence of human immunoglobulins (IgG, IgM, IgA) and the β_1c component of complement. The criterion for the presence of complexes was the staining of two or more immunoglobulins and β_1c in an identical location of sequentially cut sections. Of the 42 patients with rheumatoid arthritis (RA) 83% were positive by this criterion. In those with classic RA the incidence was 92%. Sixteen patients with fresh joint trauma or nonarthritic disease had negative findings. Among 26 patients with noninflammatory disease, 4 of 8 with polyarthritis whose features suggested primary degeneration, 1 of 11 patients with secondary degenerative arthritis, and a single case of synovial osteochondromatosis had positive findings. Among 9 patients with miscellaneous inflammatory arthritides, all of 3 with psoriatic arthritis were negative; however 2 of 6 with other inflammatory arthritides were positive. The findings in classic RA suggest that immune complexes are deposited in the articular collagenous tissues. The persistence of these complexes may play a significant role in the chronicity of the synovitis.     

Matrix metalloproteinase 10 promotion of collagenolysis via procollagenase activation: implications for cartilage degradation in arthritis

OBJECTIVE: We have previously reported the up-regulation of matrix metalloproteinase 10 (MMP-10) following treatment with the procatabolic stimulus of interleukin-1 (IL-1) and oncostatin M (OSM) in chondrocytes. Although MMP-10 is closely related to MMP-3, little is known about the role of MMP-10 in cartilage catabolism. The purpose of this study was to determine whether MMP-10 is expressed in connective tissue cells and to assess how it may contribute to cartilage collagenolysis. METHODS: MMP gene expression was assessed by real-time polymerase chain reaction using RNA from human articular chondrocytes and synovial fibroblasts stimulated with IL-1 plus OSM or tumor necrosis factor alpha (TNFalpha) plus OSM. Synovial fluid levels of MMP-10 were determined by specific immunoassay. Recombinant procollagenases were used in activation studies. Immunohistochemistry assessed MMP-10 expression in diseased joint tissues. RESULTS: MMP-10 expression was confirmed in both chondrocytes and synovial fibroblasts following stimulation with either IL-1 plus OSM or TNFalpha plus OSM, and MMP-10 was detected in synovial fluid samples from patients with various arthropathies. Exogenous MMP-10 significantly enhanced collagenolysis from IL-1 plus OSM-stimulated cartilage, and MMP-10 activated proMMP-1, proMMP-8, and proMMP-13. Immunohistochemistry revealed the presence of MMP-10 in the synovium and cartilage of an IL-1 plus OSM-induced model of arthritis as well as in samples of diseased human tissues. CONCLUSION: We confirm that both synovial fibroblasts and articular chondrocytes express MMP-10 following treatment with procatabolic stimuli. Furthermore, the detectable levels of synovial fluid MMP-10 and the histologic detection of this proteinase in diseased joint tissues strongly implicate MMP-10 in the cartilage degradome during arthritis. The ability of MMP-10 to superactivate procollagenases that are relevant to cartilage degradation suggests that this activation represents an important mechanism by which this MMP contributes to tissue destruction in arthritis.     

Appearance of calpain correlates with arthritis and cartilage destruction in collagen induced arthritic knee joints of mice.

OBJECTIVES--To determine the relevance of calpain in murine collagen induced arthritis (CIA) and to correlate the presence of m-calpain with the appearance of arthritis and cartilage destruction. METHODS--The immunohistochemical appearance and localisation of m-calpain at different stages of arthritis were analysed and compared with the histological changes occurring during type II CIA. The arthritic knee joint lavage was also examined for m-calpain by immunoelectrophoretic blotting. RESULTS--Immunohistochemical staining demonstrated a clear positive correlation between the appearance of m-calpain and both a histological grade of arthritis and an acute phase of cartilage destruction. Further development of the disease showed continual presence of m-calpain but with reduced intensity. Intra-articular inflammatory cells (mainly polymorphonuclear leucocytes, synovial lining cells, and sublining fibroblasts) were found to be the most positively stained, but extracellular localisation of m-calpain on the surface of cartilage and synovium, and in the articular cartilage matrix and chondrocyte lacunae, was also observed. In the knee joint lavage obtained at the most intensive stage of acute arthritis, m-calpain was detectable by immunoelectrophoretic blotting. CONCLUSIONS--The findings suggest that m-calpain may act at an early phase of CIA as a matrix proteinase and take part in the destruction of articular cartilage or activate other destructive enzymes.     

Epidemiology of gout and chondrocalcinosis

Gout is the most common cause of inflammatory arthritis affecting at least 1% of the population in industrialized countries. It is closely associated with hyperuricemia and is characterized by formation and reversible deposition of monosodium urate crystals in joints and extra-articular tissues. Several studies suggest that the prevalence and incidence of gout are rising. Numerous risk factors may in part explain this increasing trend including dietary and lifestyle changes, genetic factors, diuretic use and comorbid conditions such as hypertension, diabetes, cardiovascular disease, chronic renal disease and the metabolic syndrome. Chondrocalcinosis is characterized by the deposition of calcium pyrophosphate crystals in articular tissues, most commonly fibrocartilage and hyaline cartilage. Sporadic chondrocalcinosis is a common condition in the elderly and frequently associates with osteoarthritis. Hereditary haemochromatosis, hyperparathyroidism and hypomagnesaemia are metabolic disorders that predispose to secondary chondrocalcinosis.The prevalence of chondrocalcinosis is still rather uncertain and varies depending on the diagnostic criterion used in different studies.     

Differentially regulated expression of growth differentiation factor 5 and bone morphogenetic protein 7 in articular cartilage and synovium in murine chronic arthritis: potential importance for cartilage breakdown and synovial hypertrophy

OBJECTIVE: To examine whether the endogenous expression of growth differentiation factor 5 (GDF-5) and bone morphogenetic protein 7 (BMP-7) is altered in the cartilage and synovium of human tumor necrosis factor alpha (TNFalpha)-transgenic (hTNFtg) mice with chronic arthritis, and to investigate the response of hTNFtg chondrocytes as well as fibroblast-like synoviocytes (FLS) to these morphogens in vitro. METHODS: Analyses were performed in hTNFtg mice with chronic destructive arthritis and in wild-type (WT) mice as controls. Expression of GDF-5 and BMP-7 in the articular cartilage and synovium was examined by real-time polymerase chain reaction and immunohistochemistry. Human TNFtg cartilage explants, chondrocytes, and FLS monolayer cultures were assessed for basal matrix biosynthesis as well as growth factor responsiveness, using (35)S-sulfate incorporation assays. In addition, the DNA content/cell proliferation rate was measured. RESULTS: The expression of GDF-5 and BMP-7 was decreased in articular cartilage from hTNFtg mice, whereas expression of both morphogens was increased in arthritic synovium from hTNFtg mice, as compared with the levels in WT controls. Isotope incorporation revealed a marked reduction of matrix synthesis in hTNFtg cartilage as well as a decrease in responsiveness to GDF-5 and BMP-7. The DNA content did not change in arthritic cartilage as compared with WT cartilage. In hTNFtg FLS, growth factor stimulation increased the rate of cell proliferation and the production of extracellular matrix. CONCLUSION: In this murine model of TNFalpha-mediated arthritis, the expression of GDF-5 and BMP-7 is regulated differentially in articular cartilage and synovium. In articular cartilage, the down-regulation of GDF-5 and BMP-7, which function to maintain matrix integrity, could potentially compromise tissue repair, whereas in synovium, the increased expression of GDF-5 and BMP-7 might contribute to synovial hypertrophy.     

Articular responses to purified cartilage proteoglycans

To examine whether proteoglycans (PGs) liberated from cartilage might contribute to articular changes in arthritis, cartilage PGs were injected intraarticularly into rabbit knee joints. Twice-weekly injections of PG (2.5 mg) provoked synovial hypertrophy, synovitis, erosion of the articulating surfaces, and loss of metachromasia of the articular cartilage. These changes were accompanied by a marked elevation in the production of neutral collagenase and gelatinase by both synoviocytes and chondrocytes. The synoviocytes of experimental knee joints also produced factor(s), possibly related to interleukin-1, which provoked the activation of chondrocytes. Our data are consistent with the idea that free PG fragments mediate some of the pathophysiologic changes that occur in arthritic joints. This property may be particularly important in osteoarthritis.     

Metalloproteinases and cartilage proteoglycan depletion in chronic arthritis. Comparison of antigen-induced and polycation-induced arthritis

Chronic monarticular arthritis can be induced in ovalbumin-sensitized rabbits by intraarticular injection of ovalbumin (antigen-induced arthritis) or in naive rabbits by injecting hyaluronic acid mixed with the polycation poly-D-lysine (polycation-induced arthritis). Both models show some points of similarity, including joint swelling, the presence of inflammatory leukocytes and the inflammatory mediator prostaglandin E2, and the kinetics of cartilage proteoglycan loss. However, the assessment of the capacity of synovial lining and articular cartilage to synthesize and secrete neutral metalloproteinases reveals a difference between these models. We found that articular cartilage from the inflamed joints of rabbits with antigen-induced arthritis did not synthesize neutral metalloproteinases, although the synovial lining did. In contrast, both the synovial lining and the articular cartilage from the inflamed joints of rabbits with polycation-induced arthritis synthesized neutral metalloproteinases. These findings suggest that in inflammatory synovitis, different mechanisms can operate to produce damage to the matrix of articular cartilage.