Articular Cartilage In Patients Research Articles

Deficiency in N-acetylgalactosamine-6-sulfate sulfatase results in collagen perturbations in cartilage of Morquio syndrome A patients

Aim To investigate extracellular matrix (ECM) characteristics of cortical bone and articular cartilage of patients with Morquio syndrome A, a lysosomal storage disease caused by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Patients and methods Cartilage, bone, and fibroblasts from 2 unrelated patients with Morquio syndrome were used. Histological analysis on bone and cartilage was carried out by means of light and electron microscopy. Lysyl hydroxylation and cross-linking of collagen present in bone, cartilage, and fibroblast cultures was determined by reverse-phase high performance liquid chromatography. Results No histological or biochemical differences were seen in cortical bone; furthermore, no differences were seen in the amount and modification of collagen deposited by fibroblasts. Articular cartilage showed major differences: collagen fibrils show a wider range of fibril diameter, the fibrils are in mean thicker, the lysyl hydroxylation level of the triple helix is strongly decreased, the total amount of pyridinolines is in the lower ranges, and the ratio hydroxylysylpyridinoline to lysylpyridinoline is decreased. Changes were also observed with respect to the arrangement of proteoglycans in the extracellular matrix surrounding the chondrocytes. Conclusion The collagen of bone and the collagen deposited by fibroblasts is normal, whereas the ECM of cartilage in Morquio syndrome A patients is affected. Thus, deficiency in N-acetylgalactosamine-6-sulfate sulfatase has an impact on the phenotypic properties of chondrocytes, resulting in the formation of cartilage that is more prone to degeneration, being an explanation for the occurrence of osteoarthritis in Morquio syndrome A patients at early age.

The ubiquitin–proteasome pathway and viral infections in articular cartilage of patients with osteoarthritis

Many viruses can evolve different strategies to exploit the ubiquitin-proteasome pathway (UPP) for their own benefit. Some data have recently established connections between UPP and osteoarthritis (OA). The aim of this study was to determine the possible involvement of viral infections linked with the UPP in the physiopathology of OA. Samples of human cartilage were obtained from 12 patients with clinical and radiological features of OA and from 12 normal controls. DNA was extracted from cultured chondrocytes from these patients, and quantitative real-time PCR was performed to analyse the DNA/RNA prevalence and viral loads of HSV, EBV, HCMV, enterovirus, and HTLV-1. The prevalence of total viral DNA/RNA among patients with OA was 16.7% (mean viral load of 7.86 copies/mug DNA), EBV being responsible for the two positive samples, while the prevalence in controls was 0%. We did not detect any positive samples for HSV, CMV, enterovirus, and HTLV-1 among patients with OA and controls. This first approach to the study of the prevalence of viruses linked to the UPP in articular cartilage of end-stage OA patients provides evidences supporting the risk of EBV transmission or reactivation in a subset of patients with disorders requiring tissue regeneration.

Hypoxia upregulates the expression of angiopoietin‐like‐4 in human articular chondrocytes: Role of angiopoietin‐like‐4 in the expression of matrix metalloproteinases and cartilage degradation

The objective of this article was to investigate the role and expression of a novel adipocytokine, angiopoietin-like-4 (ANGPTL4), in arthropathy. Human chondrocytes were obtained from articular cartilage of patients with rheumatoid arthritis (RA) and osteoarthritis (OA), who underwent total knee or hip arthroplasty. Isolated chondrocytes were cultured under hypoxic (95% N(2), 5% CO(2)) or normoxic conditions. The effects of hypoxia on ANGPTL4 expression were determined by real-time reverse transcription polymerase chain reaction and Western blot analysis. We examined the role of ANGPTL4 using small interference RNA or by stimulating chondrocytes with recombinant ANGPTL4 protein. ANGPTL4 expression in the articular cartilage specimens was examined by immunohistochemistry. Hypoxia induced a significant increase in ANGPTL4 production (p < 0.05). Incubation of chondrocytes in vitro with recombinant ANGPTL4 enhanced the expression of matrix metalloproteinase (MMP)-1 and MMP-3. Downregulation of ANGPTL4 mRNA expression by siRNA diminished the expression of MMP-1, but not that of MMP-3, suggesting that each proteinase has a distinct response to ANGPTL4. Although the in vitro responses of chondrocytes to hypoxia were similar between RA and OA samples, the in vivo expression of ANGPTL4 had unique disease-specific patterns, suggesting differences in oxygen tension in vivo. Human chondrocytes expressed ANGPTL4 and the expression was enhanced by hypoxia. ANGPTL4 might modulate cartilage metabolism by regulating MMPs.

Long-term NSAID treatment directly decreases COX-2 and mPGES-1 production in the articular cartilage of patients with osteoarthritis

To simultaneously study the effect of a selective cyclooxygenase-2 (COX-2) inhibitor and that of a classic non-steroidal anti-inflammatory drug (NSAID) on the expression of pro-inflammatory genes in the cartilage of patients with severe knee osteoarthritis (OA) and in cultured human OA chondrocytes. A 3-month clinical trial was carried out on 30 patients with severe knee OA scheduled for knee replacement surgery. Patients were randomized into two groups: patients treated with celecoxib (CBX) and patients treated with aceclofenac (ACF). OA patients who did not want to be treated served as the control group. After surgery, cartilage was processed for molecular biology studies. We also employed cultured chondrocytes from different OA patients to examine NSAID effects on pro-inflammatory gene expression in cells stimulated with interleukin (IL)-1beta. Both CBX and ACF inhibited COX-2, microsomal prostaglandin E synthase-1 (mPGES-1) and inducible nitric oxide synthase (iNOS) synthesis in the articular cartilage of OA patients. In cultured chondrocytes, both NSAID decreased COX-2 and mPGES-1 synthesis and prostaglandin E2 (PGE2) release induced by IL-1beta, while no effect was observed on nitric oxide or iNOS synthesis. In OA patients, only CBX decreased tumor necrosis factor alpha and IL-1beta expression in the cartilage, while both NSAID diminished IL-1beta induced cytokine synthesis in cultured OA chondrocytes. Both NSAID diminished PGE2 release and induced a decrease in COX-2 and mPGES-1 synthesis in the cartilage from OA patients and in OA chondrocytes. These data suggest that prolonged therapy with PGE2 blocking agents decreases PGE2 production not only by direct inhibition of COX-2 activity, but also by down-regulating COX-2 and mPGES-1 synthesis in the cartilage. However, CBX and ACF seem to have a different anti-inflammatory profile in controlling pro-inflammatory gene expression in the cartilage.

Technology Insight: adult mesenchymal stem cells for osteoarthritis therapy

Despite the high prevalence and morbidity of osteoarthritis (OA), an effective treatment for this disease is currently lacking. Restoration of the diseased articular cartilage in patients with OA is, therefore, a challenge of considerable appeal to researchers and clinicians. Techniques that cause multipotent adult mesenchymal stem cells (MSCs) to differentiate into cells of the chondrogenic lineage have led to a variety of experimental strategies to investigate whether MSCs instead of chondrocytes can be used for the regeneration and maintenance of articular cartilage. MSC-based strategies should provide practical advantages for the patient with OA. These strategies include use of MSCs as progenitor cells to engineer cartilage implants that can be used to repair chondral and osteochondral lesions, or as trophic producers of bioactive factors to initiate endogenous regenerative activities in the OA joint. Targeted gene therapy might further enhance these activities of MSCs. Delivery of MSCs might be attained by direct intra-articular injection or by graft of engineered constructs derived from cell-seeded scaffolds; this latter approach could provide a three-dimensional construct with mechanical properties that are congruous with the weight-bearing function of the joint. Promising experimental and clinical data are beginning to emerge in support of the use of MSCs for regenerative applications.

Fast T2 mapping of the patellar articular cartilage with gradient and spin-echo magnetic resonance imaging at 1.5 T: validation and initial clinical experience in patients with osteoarthritis

To evaluate the T2 mapping of patellar articular cartilage in patients with osteoarthritis using gradient and spin-echo (GRASE) magnetic resonance (MR) imaging. After the imaging of a phantom consisting of two sealed 50-ml test objects with different concentrations (30% and 90% weight/volume) of copper sulphate, the T2 mapping of patellar articular cartilage was performed in 35 patients (21 male and 14 female; mean age +/- SD 42+/-17 years) with moderate degree of patellar osteoarthritis. Turbo-spin-echo (TSE) (TR milliseconds/ minimum-maximum TE milliseconds 3,000/15-120; total acquisition time 5 min 52 s) and GRASE (TR milliseconds/ minimum-maximum TE milliseconds 3,000/15-120; total acquisition time 1 min 51 s) were employed. In each patient patellar cartilage was segmented at nine locations (three superior, three central, and three inferior) by manually defined regions of interest. T2 relaxation times were calculated using a linear fit applied to the logarithm of signal intensity decay. In the phantom the T2 values measured by GRASE were similar to those measured by MR spectroscopy (test object 1: 48.1 ms vs 51 ms; test object 2: 66.8 ms vs 71 ms; P>0.05, Wilcoxon test). In patients GRASE and TSE-derived T2 values demonstrated good agreement (mean difference +/- SD, 1.81+/-3.63 ms). The within-patient coefficient of variation was 22% for TSE and 23% for GRASE. Fast T2 mapping of the patellar articular cartilage can be performed with GRASE within a third of the time of that of standard sequences.

Treatment of Femoro-Acetabular Impingement with Surgical Dislocation and Débridement in Young Adults

Femoro-acetabular impingement has been associated with acetabular labral and/or articular cartilage damage that may ultimately result in osteoarthritis of the hip. Surgical treatment of femoro-acetabular impingement is directed at restoring a more normal femoral head-neck offset to alleviate femoral abutment against the acetabular rim and treating associated labral and articular cartilage damage. Thirty hips with femoro-acetabular impingement (in twenty-nine patients) underwent débridement through a greater trochanteric flip osteotomy and anterior dislocation of the femoral head. There were sixteen male patients and thirteen female patients with a mean age of thirty-one years. Cam (femoral based) impingement was noted in fourteen hips; pincer (acetabular based) impingement, in one hip; and combined cam and pincer impingement, in fifteen hips. The mean duration of clinical and radiographic follow-up was thirty-two months. All patients were followed according to a prospective protocol, with Harris hip scores and plain radiographs obtained preoperatively and at six months, one year, and annually for a minimum of two years. The mean Harris hip score improved from 70 points preoperatively to 87 points at the time of final follow-up (p < 0.0001). Osteonecrosis did not develop in any hip, and there were no trochanteric nonunions. In eighteen hips, severe damage of the acetabular articular cartilage that had not been appreciated on preoperative plain radiographs or magnetic resonance arthrography was noted on arthrotomy. Eight of these eighteen hips subsequently had radiographic evidence of progression of the osteoarthritis, and four of the eight hips required or were expected to soon require conversion to a total hip arthroplasty to treat progressive pain. At the time of early follow-up, we found that surgical dislocation and débridement of the hip for the treatment of femoro-acetabular impingement in hips without substantial damage to the articular cartilage can reduce pain and improve function. This procedure has a low rate of complications. Radiographic signs of progression of osteoarthritis and clinical failure requiring conversion to a total hip arthroplasty were seen only in patients with severe damage to the acetabular articular cartilage, a finding that emphasizes the need for better imaging methods to assess the extent of damage to the acetabular articular cartilage in patients with this disorder.

Distinct signaling pathways are involved in hypoxia- and IL-1-induced VEGF expression in human articular chondrocytes

Recent data suggest that vascular endothelial growth factor (VEGF) is involved in the pathogenesis of osteoarthritis (OA). Cartilage is an avascular tissue, leading to a low cartilage O2 level. Thus, in a variety of pathologic or physiologic conditions, VEGF is partly regulated by hypoxic stress. The implications of hypoxia for VEGF expression by OA chondrocytes, however, are not known. We investigated the regulatory system of VEGF in OA chondrocytes under hypoxic conditions. Chondrocytes were obtained from articular cartilage of patients with OA. Cells were cultured and then incubated under hypoxic (95% N2, 5% CO2) or normoxic conditions, with or without interleukin (IL)-1 (10 ng/mL) stimulation. The mitogen activated protein kinase (MAPK) inhibitors were also used. VEGF levels in the culture supernatants were measured using an enzyme-linked immunosorbent assay. Western blot analysis was used to examine the expression of hypoxia inducible factor (HIF)-1alpha. Hypoxia significantly increased VEGF levels (p<0.05). Hypoxia-induced VEGF secretion was abolished by p38MAPK inhibitor, but not by JNK inhibitor. In contrast, IL-1-induced VEGF secretion was blocked by JNK inhibitor, and not by p38MAPK inhibitor. Both hypoxia and IL-1-induced HIF-1alpha were attenuated by p38 MAPK and JNK inhibitors. We demonstrate that hypoxia and IL-1 induce VEGF production in chondrocytes through distinct MAPK signaling pathways, indicating that VEGF is induced in a HIF-1-dependent or -independent manner in chondrocytes.

Multidetector Computed Tomography of Pediatric Lateral Condylar Fractures

The objective of this study was to compare lateral condylar fracture characterization using radiographs and multidetector computed tomography (MDCT) of the elbow and to evaluate outcomes in a group of children managed based on MDCT findings. Unenhanced MDCT of the elbow with sagittal and coronal reformations was prospectively performed without sedation in 10 children between 1 and 16 years of age with lateral condylar fractures identified on frontal and lateral radiographs of the elbow. Two blinded readers reviewed all radiographs and MDCT images independently and in consensus. For the radiographs and MDCT images, readers graded the displacement of the lateral condyle fracture fragment and classified the fractures according to the Milch classification. Articular and epiphyseal cartilage integrity was assessed on MDCT. Patients were managed based on the consensus interpretation of the MDCT study. The frequency of interobserver agreement, discordant grading of fracture displacement and fracture classification between radiographs and MDCT images, and altered management based on the MDCT findings were determined. Individual readers agreed on fracture displacement in 9 patients (90%) on radiographs and in all 10 patients (100%) on MDCT. Individual readers agreed on fracture classification in 4 patients (40%) on radiographs and in 9 patients (90%) on MDCT. In 4 patients (40%), grading of fracture displacement differed between the consensus interpretation of the radiographs and MDCT images. In 6 patients (60%), fracture classification differed between the consensus interpretation of the radiographs and MDCT images. All 3 patients with fracture displacement greater than 5 mm and 1 patient with fracture displacement between 2 and 5 mm demonstrated disruption of the articular and epiphyseal cartilage on MDCT. Two patients (20%) with fracture displacement near the surgical threshold of 2 mm had altered management based on the MDCT findings. All patients progressed to complete fracture healing, with no delayed displacement or other complications. Multidetector computed tomography is a highly reproducible means of characterizing pediatric lateral condylar fractures and frequently demonstrates disruption of the epiphyseal and articular cartilage in patients with fracture displacement greater than 2 mm. The findings of MDCT may lead to altered treatment in patients with fracture displacement near the surgical threshold of 2 mm.

Fat-Suppressed 3D Spoiled Gradient-Echo MRI and MDCT Arthrography of Articular Cartilage in Patients with Hip Dysplasia

Our objective was to assess the diagnostic ability of MDCT arthrography for acetabular and femoral cartilage lesions in patients with hip dysplasia. A disorder of the articular cartilage was evaluated in 20 hips of 18 patients with acetabular dysplasia who did not have osteoarthritis or who had early stage osteoarthritis before undergoing pelvic osteotomy surgery. The findings on fat-suppressed 3D fast spoiled gradient-echo MRI and MDCT arthrography of the hip were evaluated by two independent observers, and sensitivity, specificity, and accuracy were determined using arthroscopic findings as the standard of reference. Kappa values were calculated to quantify the level of interobserver agreement. The sensitivity and specificity for the detection of any cartilage disorder (grade 1 or higher) were (observer 1/observer 2) 49%/67% and 89%/76%, respectively, on MRI, and 67%/67% and 89%/82%, respectively, on CT arthrography. The sensitivity and specificity for the detection of cartilage lesions with substance loss (grade 2 or higher) were (observer 1/observer 2) 47%/53% and 92%/87%, respectively, on MRI, and 70%/79% and 93%/94%, respectively, on CT arthrography. CT arthrography provided significantly higher sensitivity in the detection of grade 2 or higher lesions than MRI for both observers. Interobserver agreement in the detection of grade 2 or higher cartilage lesions was moderate (kappa = 0.53) on MRI and substantial (kappa = 0.78) on CT. MDCT arthrography is a sensitive and reproducible method for assessing articular cartilage lesions with substance loss in patients with hip dysplasia.

Chromosomal abnormalities are related to location and grade of osteoarthritis

To investigate the frequency of numerical aberrations of chromosomes 7, X and Y in patients with osteoarthritis (OA) by performing fluorescent in situ hybridization (FISH) studies on articular cartilage, and to correlate the chromosomal changes with the degree and location of articular involvement. Thirty-four women and 10 men with OA were included in the study. As a control group, 6 women and 5 men operated for orthopedic disorders other than OA were analyzed. FISH studies were performed on hip or knee cartilage, using two-color centromere-specific probes for chromosomes 7 & X for women and 7 & Y for men. FISH analysis revealed that 46% of OA patients had numerical abnormalities of chromosomes 7, X or Y. An extra chromosome 7 (trisomy 7) was present in 35% of patients with chromosomal aberrations. All males with OA lost the Y chromosome while 15% of the women had loss of one chromosome X (monosomy X). Trisomy 7 was associated with hip OA (p=0.019) and advanced OA according to the Kellgren and Lawrence classification (p=0.05). None of the 11 controls showed abnormalities in the chromosomes analyzed. FISH analysis showed the presence of numerical chromosomal abnormalities in the articular cartilage of patients with OA.

Comparison of MRI graded cartilage and MRI based volume measurement in knee osteoarthritis.

The aim of this study was to investigate the relationship between the femoral, tibial and patellar cartilage volume and MRI grading of the articular cartilage in patients with knee OA. Articular cartilage volumes of 65 postmenopausal women were determined by processing images acquired in the sagittal plane using a fast spin echo proton density-weighted sequence. The articular cartilages were divided into 5 compartments including lateral and medial tibial, lateral and medial femoral and patellar compartments. The articular cartilages were graded using a modified Outerbridge classification. Grade 0 indicated intact cartilage, grade 1 chondral softening with normal contour, grade 2 superficial fraying, grade 3 surface irregularity and thinning and grade 4 full thickness cartilage loss. The grades of articular cartilage were compared with cartilage volume measurements. In medial femoral cartilage, grade 1 had more volume compared to grade 0 cartilage (p: 0.017). In medial tibial cartilage, grade 1 had more volume compared to grade 0 and grade 2 cartilage (p: 0.045 and p: 0.027, respectively). In patellar cartilage, grade 1 cartilage had significantly more volume than grade 0 cartilage (p: 0.007). In lateral tibial and femoral cartilages, no significant difference was observed between grade 0 and grade 1 cartilage. Cartilage volume correlates well with MR grading of articular cartilage. The higher the grade of the cartilage the less the volume, with the exception of grade 1 lesions. Grade 1, reflects oedema in the cartilage and has a conflicting effect on volume measurement. The combination of MRI based volume measurement and grading of articular cartilage may provide an accurate method for the non-invasive evaluation and follow-up of articular cartilage.

Comparison of MRI graded cartilage and MRI based volume measurement in knee osteoarthritis.

The aim of this study was to investigate the relationship between the femoral, tibial and patellar cartilage volume and MRI grading of the articular cartilage in patients with knee OA. Articular cartilage volumes of 65 postmenopausal women were determined by processing images acquired in the sagittal plane using a fast spin echo proton density-weighted sequence. The articular cartilages were divided into 5 compartments including lateral and medial tibial, lateral and medial femoral and patellar compartments. The articular cartilages were graded using a modified Outerbridge classification. Grade 0 indicated intact cartilage, grade 1 chondral softening with normal contour, grade 2 superficial fraying, grade 3 surface irregularity and thinning and grade 4 full thickness cartilage loss. The grades of articular cartilage were compared with cartilage volume measurements. In medial femoral cartilage, grade 1 had more volume compared to grade 0 cartilage (p: 0.017). In medial tibial cartilage, grade 1 had more volume compared to grade 0 and grade 2 cartilage (p: 0.045 and p: 0.027, respectively). In patellar cartilage, grade 1 cartilage had significantly more volume than grade 0 cartilage (p: 0.007). In lateral tibial and femoral cartilages, no significant difference was observed between grade 0 and grade 1 cartilage. Cartilage volume correlates well with MR grading of articular cartilage. The higher the grade of the cartilage the less the volume, with the exception of grade 1 lesions. Grade 1, reflects oedema in the cartilage and has a conflicting effect on volume measurement. The combination of MRI based volume measurement and grading of articular cartilage may provide an accurate method for the non-invasive evaluation and follow-up of articular cartilage.

Denaturation of type II collagen in articular cartilage in experimental murine arthritis. Evidence for collagen degradation in both reversible and irreversible cartilage damage.

Degradation of type II collagen is thought to be a key step in the destruction of articular cartilage in patients with rheumatoid arthritis or osteoarthritis. The aim of this study was to investigate whether type II collagen degradation is associated with cartilage destruction. Type II collagen degradation was studied in two murine arthritis models, zymosan-induced arthritis (ZIA), which develops reversible articular cartilage damage based on proteoglycan analysis, and antigen-induced arthritis (AIA), in which there is irreversible damage to the cartilage. Type II collagen degradation was assayed immunohistochemically using the COL2-3/4m antibody which recognizes denatured type II collagen, such as is produced by collagenase cleavage. In both models, degradation of type II collagen was observed in the non-calcified articular cartilage of arthritic but not of control knees. In the patella-femoral compartment, collagen denaturation started to increase on day 3 (ZIA) and day 7 (AIA) and remained high on day 14. In contrast, in the tibia-femoral compartment, type II collagen breakdown was not increased before 14 days in either model. By 28 days, collagen denaturation was strongly reduced in the patella-femoral compartment in the ZIA model, but persisted in the tibia-femoral compartment in both models. In conclusion, increased type II collagen degradation was found in articular cartilage of both ZIA and AIA animals. Since ZIA does not develop irreversible cartilage destruction, this indicates that cartilage may have the ability to withstand a limited degree of type II collagen degradation without developing irreversible damage.

Keratan sulfate as a potential biomarker of loading of the intervertebral disc.

A review of the literature. To investigate the potential of serum levels of keratan sulfate as a biomarker of the effects of loading of the spine. Exposure to mechanical loading of the spine causes changes in metabolism of intervertebral discs, eventually leading to accelerated disc degeneration. This process is characterized by the degradation of proteoglycans, which is reflected by an increase in the blood level of proteoglycan components. The serum level of keratan sulfate, an epitope present on these proteoglycan components, has been suggested as a marker of changes in metabolism of cartilaginous tissues. A review of the literature on serum keratan sulfate levels in relation to degenerative changes in cartilaginous tissue. In a number of studies keratan sulfate in serum was reported to be related to degeneration of articular cartilage in patients with osteoarthritis. In addition, massive and rapid degradation of intervertebral discs was determined to result in a large rise in serum keratan sulfate levels. Whether degenerative changes of intervertebral discs induced by mechanical stress also cause a detectable increase in serum keratan sulfate should be subjected to further investigation. Quantification of keratan sulfate in serum offers a promising measure for the early effects of mechanical loading of the spine, but research is needed for validation.

Quantitative analysis of crosslinks pyridinoline and pentosidine in articular cartilage of patients with bone and joint disorders.

To determine the content of two crosslinks, pyridinoline (a mature crosslink) and pentosidine (a senescent crosslink), in human articular cartilage, and to examine the effect of bone and joint disorders on the content of those crosslinks in articular cartilage. After pretreatment with SP-Sephadex C-25, high-performance liquid chromatography was conducted on a hydrolysate of human articular cartilage from 53 patients with one of the following diseases: osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis, femoral head necrosis, and renal osteodystrophy (ROD). Pyridinoline levels were either unchanged with age or were slightly decreased in elderly patients. Pentosidine levels increased with age in the entire patient population. There was no significant difference in the pyridinoline content among the study groups, but there was a significant difference in pentosidine content (P < 0.001). ROD patients had the highest mean level of pentosidine (407 mumoles/mole of hydroxyproline), and RA patients had a higher mean level than age-matched OA patients (214 versus 103 mumoles/mole of hydroxyproline). Bone and joint disorders do not affect the pyridinoline content in articular cartilage, but they do not affect the pentosidine content.

Immunoglobulin G and serum albumin isolated from the articular cartilage of patients with rheumatoid arthritis or osteoarthritis contain covalent heteropolymers with proteoglycans.

The present study was undertaken to identify the cartilage matrix molecules that are bound with intermolecular disulfide bonds to IgG and serum albumin molecules recovered from the articular cartilage of patients with rheumatoid arthritis (RA) or osteoarthritis (OA). The cartilage specimens were extracted sequentially with three changes of neutral buffer, three changes of 6 M guanidine hydrochloride and then partially degraded with bacterial collagenase. The extracted IgG and albumin, along with matrix molecules bound to these proteins, were isolated with affinity chromatography using antibodies to IgG or human serum albumin conjugated to agarose beads. The isolated materials were characterized with sodium dodecyl sulfate polyacrylamide gel electrophoresis and transfer blotting, using specific antibodies to IgG, albumin, and proteoglycans. In the isolated materials, heteropolymers with IgG or albumin were identified. These polymers contained keratan sulfate and less frequently chondroitin-4-sulfate and chondroitin-6-sulfate. These findings identified the keratan sulfate rich proteoglycans, prevalent at the surface of joint cartilage, as the most common cartilage matrix molecules that are covalently bound to IgG or to serum albumin by disulfide bonds in the articular cartilage of patients with RA or OA.

Activity of metalloproteases and glycosyl-transferases in the articular cartilage of patients with hip osteoarthritis (OA) treated with naproxen

Activity of metalloproteases and glycosyl-transferases in the articular cartilage of patients with hip osteoarthritis (OA) treated with naproxen

Immune deposits in articular cartilage of patients with rheumatoid arthritis have a granular pattern not seen in osteoarthritis

Frozen sections of articular cartilage, obtained from patients with rheumatoid arthritis (RA) or osteoarthritis (OA) undergoing joint replacement, were stained with fluoresceinated specific antisera to IgG, IgM, IgA, C1q, C4, and C3. Specimens positive for IgG were examined for IgG subclasses using mouse monoclonal antibodies. IgG was present in 22 of 34 cartilage specimens obtained from patients with RA, and in 14 of these 22 patients, a granular pattern was present. IgM, IgA, C1q, and C3 when present showed a similar granular pattern. In articular cartilage of patients with RA, all IgG subclasses tended to be present. The remaining eight specimens positive for IgG from patients with RA had staining patterns also seen in patients with OA. IgG staining was present in 31 of 117 cartilage specimens obtained from patients with OA and none had the granular pattern seen in RA. Intermittent linear staining at the surface was the most common pattern seen in cartilage from patients with OA. The different patterns of immune deposits in articular cartilage in RA and OA suggest that antibodies with different specificities are present or that different mechanisms of immune deposit formation exist in these disorders.

Isolation and propagation of endothelial cells derived from rheumatoid synovial microvasculature.

Synovial angiogenesis may play an important part in the destruction of articular cartilage in patients with rheumatoid arthritis (RA). As an important first step towards developing in vitro models of synovial angiogenesis, microvascular endothelial cells have been isolated, purified, and cultured from operative synovial specimens obtained from adult patients with RA.