Superoxide dismutase activity is significantly lower in end-stage osteoarthritic cartilage than non-osteoarthritic cartilage

Recent studies have shown that superoxide dismutase 1 (SOD1), SOD2, and SOD3 are significantly decreased in human osteoarthritic cartilage. SOD activity is a marker that can be used to comprehensively evaluate the enzymatic capacities of SOD1, SOD2, and SOD3; however, the trend of SOD activity in end-stage osteoarthritic tissues remains unknown. In the present study, we found that SOD activity in end-stage osteoarthritic synovium of the knee was significantly lower than that in control synovium without the influence of age. The SOD activity was significantly lower in the end-stage knee osteoarthritic cartilage than in the control, but a weak negative correlation was observed between aging and SOD activity. However, SOD activity in end-stage hip osteoarthritic cartilage was significantly lower than that in control cartilage without the influence of aging. The relationship between osteoarthritis and SOD activity was stronger than the relationship between aging and SOD activity. These results indicate that direct regulation of SOD activity in joint tissues may lead to suppression of osteoarthritis progression.

Functional Characterization of the Osteoarthritis Susceptibility Mapping to CHST11-A Bioinformatics and Molecular Study

The single nucleotide polymorphism (SNP) rs835487 is associated with hip osteoarthritis (OA) at the genome-wide significance level and is located within CHST11, which codes for carbohydrate sulfotransferase 11. This enzyme post-translationally modifies proteoglycan prior to its deposition in the cartilage extracellular matrix. Using bioinformatics and experimental analyses, our aims were to characterise the rs835487 association signal and to identify the causal functional variant/s. Database searches revealed that rs835487 resides within a linkage disequilibrium (LD) block of only 2.7 kb and is in LD (r² ≥ 0.8) with six other SNPs. These are all located within intron 2 of CHST11, in a region that has predicted enhancer activity and which shows a high degree of conservation in primates. Luciferase reporter assays revealed that of the seven SNPs, rs835487 and rs835488, which have a pairwise r² of 0.962, are the top functional candidates; the haplotype composed of the OA-risk conferring G allele of rs835487 and the corresponding T allele of rs835488 (the G-T haplotype) demonstrated significantly different enhancer activity relative to the haplotype composed of the non-risk A allele of rs835487 and the corresponding C allele of rs835488 (the A-C haplotype) (p < 0.001). Electrophoretic mobility shift assays and supershifts identified several transcription factors that bind more strongly to the risk-conferring G and T alleles of the two SNPs, including SP1, SP3, YY1 and SUB1. CHST11 was found to be upregulated in OA versus non-OA cartilage (p < 0.001) and was expressed dynamically during chondrogenesis. Its expression in adult cartilage did not however correlate with rs835487 genotype. Our data demonstrate that the OA susceptibility is mediated by differential protein binding to the alleles of rs835487 and rs835488, which are located within an enhancer whose target may be CHST11 during chondrogenesis or an alternative gene.

[Features of biochemical changes in blood serum according to the form of progression of idiopathic and dysplastic coxarthrosis]

Carried out biochemical studies of blood serum (collagenase activity, glycosamineglicans and hydroxyproline fractions) of 72 patients with hip idiopathic osteoarthrosis and 30 patients with dysplastic osteoarthrosis of the iv-th stage in.accordance with J. H. Kellgren and J. S. Lavrence depending on the form of pathologic process progression. It has been proved that both with idiopathic and dysplastic coxartrosis metabolism of basic protein of osteochonrous tissue was broken both in catabolic and in synthetic phase of this process. The most deep changes 1 of biochemical values (collagenase, free and proteinbinded hydroxyprolines, the content of glycosamines) have been observed with rapid form of course progression of idiopathic and dysplastic coxarthrosis. Definite appropriateness promotesin.patients better understanding of coxarthrosis pathogenese, development of diagnostic and medical measures for patients with this severe orthopedic pathology.

Increased type II deiodinase protein in OA-affected cartilage and allelic imbalance of OA risk polymorphism rs225014 at DIO2 in human OA joint tissues

OBJECTIVE

Genetic variation at the type II deiodinase (D2) gene (DIO2) was previously identified as osteoarthritis (OA) risk factor. To investigate mechanisms possibly underlying this association, we assessed D2 protein in healthy and OA-affected cartilage and investigated allelic balance of the OA risk polymorphism rs225014 at DIO2 in human OA joints.

METHODS

Immunohistochemical staining of healthy and OA-affected cartilage was performed for D2. We then assessed allelic balance of DIO2 mRNA within OA-affected cartilage both at and away from the lesion, ligaments and subchondral bone. Allelic balance was measured by the amount of alleles 'C' and 'T' of the intragenic OA risk polymorphism rs225014 in heterozygous carriers.

RESULTS

A markedly higher amount of D2 positive cells and staining intensity was observed in OA cartilage. A significant, 1.3-fold higher presence was observed for the OA-associated rs225014 'C' allele relative to the 'T' allele of DIO2, which was significant in 28 of 31 donors.

CONCLUSION

In OA cartilage, D2 protein presence is increased. The allelic imbalance of the DIO2 mRNA transcript, with the OA risk allele 'C' of rs225014 more abundant than the wild-type 'T' allele in heterozygote carriers provides a possible mechanism by which genetic variation at DIO2 confers OA risk.

Oxidative equilibrium in the prophylaxis of degenerative joint changes: an analysis of pre- and postoperative activity of antioxidant enzymes in patients with hip and knee osteoarthritis

BACKGROUND

Osteoarthritis is often accompanied by disturbance of oxidative equilibrium. The aim of the study was to analyze antioxidant defense system function in patients with hip and knee osteoarthritis by assessing superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity in erythrocytes.

MATERIAL/METHODS

The study included 26 women and 18 men who underwent hip or knee arthroplasty. The pre- and postoperative activities of the antioxidant enzymes were evaluated. SOD activity was determined using the Misra/Fridovich method, CAT by the Beer/Seizer method, and the activity of GPx by the Paglia/Valentine method. The results were compared with those of a healthy control group.

RESULTS

SOD activity of the patients was insignificantly lower than in the control group. However, after arthroplasty it increased in subgroups: in males by 13% (p<0.04), in females by 7% (p<0.05), in the group <69 years of age by ca. 14%) (p<0.01), and in the group with idiopathic OA by 12% (p<0.005). The activities of CAT and GPx in all the patient groups were significantly higher than in the controls. It increased even more on the 10th day after arthroplasty with the exception of the patients with rheumatoid osteoarthritis, in whom a decrease by 65.5% (p<0.008) were found, and in the patients > or =69 years old by 9.3% (NS).

CONCLUSIONS

Knowledge of antioxidant enzyme activity might offer new targets for future therapeutic methods for the treatment of degenerative joint disease.

[Influence of copper (II) complex on the activity of selected oxidative enzymes]

Coxarthrosis results in physical limitations (hypokinesis) and a necessity to change one's life style to the one that does not require much movement. Physical inactivity leads rapidly to metabolic processes inhibition. The processes of protein, carbohydrate and lipid catabolism intensify. Abnormal metabolism of polyunsaturated fatty acids occurs, which consequently leads to the development of reactive oxygen species (ROS) and to the acceleration of lipid peroxidation. Therefore, it is well-founded to seek for a new group of compounds demonstrating interesting biochemical properties. Among such already known compounds are chromone, azole and flavone derivatives, known for their oxidative properties. The aim of the study was to assess the antioxidant enzymes: catalase (CAT) and glutathione peroxidase (GPX) in erythrocytes in 25 patients suffering from coxarthrosis in comparison with healthy persons.

MATERIALS AND METHODS

The activity of catalase was determined in erythrocytes using the method of Beers and Sizer at 240 nm on the Beckman spectrophotometer. The activity of glutathione peroxidase was estimated using the method of Little and O'Brien at 412 nm on the Beckman spectrophotometer. The research was conducted with the permit of the Bioethics Committee No RNN/260/08/KB dated 20.05.2008. Blood for the tests was taken from periulnar vein to anticoagulant tubes (EDTA). The group consisted of 25 patients hospitalized in the Trauma and Orthopaedic Ward of the Hospital in Łódź.

RESULTS

The results of the tests on erythrocytes in the patients with physical limitations reveal the increase of glutathione peroxidase and catalase activity by about 50% in all patients, who were administered the dichlorobis (N1-dichloromethyl-3,5-dimethylpyrazole, copper (II) compound in comparison to the control group, where the foregoing compound was not used.

CONCLUSION

The research results significantly emphasise that adding of new chemical compounds to blood in investigation of oxidative properties has a considerable influence on the activity of the selected enzymes (catalase and glutathione peroxidase) in comparison to the control group. The research reveals an increase of the activity of all antioxidant enzymes, where newly synthesized chemical compounds were used. The results of antioxidative capacity tests confirmed that complex compounds with Cu (II) ions have a significant influence on the antioxidative status. The studies on the foregoing enzymes also indicate that overproduced free radicals participate in the whole course of the coxarthrosis.

[Influence of chromone compounds on the activity of selected antioxidant enzymes in patients with physical limitations]

Coxarthrosis used to be referred to as the "doctors' cross" pointing to the difficulties of the treatment. Degenerative processes in the bones usually concern large joints: knee joints in 25-40% of cases, similarly in case of hip joints. Because of the role the joints play, the arthrosis may result in physical limitations or disability. The aim of the study was to evaluate the activity of catalase and superoxide dismutase (CuZn-SOD) in erythrocytes in patients suffering from the coxarthrosis--as the studied group and in healthy people--as the control group.

MATERIALS AND METHODS

Determining the activity of catalase and superoxide dismutase in the group of 17 patients hospitalized because of coxarthrosis.

RESULTS

In the study about 90% increase of the activity of the enzymes was determined in the studied group, in which the chemical compound 3{(2-aminothiazolyl)methylene}4H-1-benzopyran-4-one was added to the blood, in comparison with the control group.

CONCLUSION

The results of the test on catalase and superoxide dismutase clearly indicate that the free radicals participate in the whole course of coxarthrosis.

[Activity of superoxide dismutase (CuZn-SOD) in erythrocytes of patients after hips alloplasty]

Hip osteoarthritis leads, among others, to abnormally decreased physical activity (hypokinesia). Adverse effect of physical inactivity can cause inhibition of anabolic processes in favour of enhancement of protein, carbohydrate, and lipid catabolitic reactions, as well as inadequate metabolism of polyunsaturated fatty acids. These alterations can induce an increased lipid peroxide synthesis, overproduction of reactive oxygen species (ROS) and acceleration of lipid peroxidation processes. The aim of the study was to determine superoxide dismutase activity (CuZn-SOD) in red blood cells of patients suffering from hip osteoarthritis prior to and following total alloplasty as compared to healthy subjects, and also to evaluate effect of hypokinesia on oxidative stress. MATERIAL AND METHODS; CuZn-SOD activity in red blood cells was determined according to the Misra and Fridovich method in 36 patients with hip osteoarthritis hospitalized at the Traumatic-Orthopaedic Department of the Ministry of Internal Affairs and Administration Hospital in Lódź.

RESULTS

In patients with decreased physical activity in ten days after alloplasty, enzyme activity increased (+24.9%), one month since the operation it decreased, but it higher as compared to result activity of CuZn-SOD prior to surgery (+16.8%).

CONCLUSIONS

The results activity of superoxide dysmutase leads to ROS generation and their overgeneration in hip osteoarthritis and in first time of treatment.

Alendronate decreases TRACP 5b activity in osteoarthritic bone

The activity of a tartrat-resistant acid phosphatase 5B (TRACP 5b), a marker of osteoclast function, was quantified in osteoarthritic bone specimens from patients treated with Alendronate. Prior to total hip replacement, 12 patients were randomized in a bisphosphonate and a control group. The bisphosphonate group received daily oral Alendronate for 50 days before operation. After operation, the femoral heads were harvested. Samples of the anterior femoral head (A1) and the intertrochanteric area (A2) were taken, analyzed with an immunoassay and stained for TRACP 5-positive-cells. The immunoassay revealed that TRACP-5b activity of the bisphosphonate group was significantly increased in A1 compared to A2, but not of the control group. Bisphosphonate treatment decreased enzyme activity compared to the controls: 0.41 U/mg vs. 0.31 U/mg in A1 and 0.26 U/mg vs. 0.18 U/mg in A2 (p<0.05). The histological examination shows significantly less TRACP-positive cells in bisphosphonate-treated bone sections, confirming the results. Our data suggest that bisphosphonates reduce TRACP 5b activity in the intertrochanteric area rather than in the anterior femoral head. Consequently, they are more effective in areas of well-supplied bone than in osteoarthritic bone tissue.

Increased level of cytokines and matrix metalloproteinases in osteoarthritic subchondral bone

OBJECTIVE

The aim of this study was to investigate the expression of several cytokines, matrix metalloproteinases (MMPs), and tissue inhibitor of matrix metalloproteinases (TIMP)-1 in osteoarthritis (OA) and control sera and different joint tissues.

METHODS

Serum, synovial fluid, cartilage, synovial and subchondral bone tissues were examined in OA and control subjects. The protein level of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, IL-8, IL-10 and MMP-2, MMP-3, MMP-9, and TIMP-1 were measured by immunoanalysis.

RESULTS

Serum levels of TNF-alpha, MMP-3 and -9 were significantly higher in OA patients than in controls. Conversely, serum IL-10 was decreased in OA patients. CRP was elevated when compared to healthy controls and decreased significantly 6 months after the surgery. In contrast to control samples, OA cartilage and synovium revealed significantly higher MMP-2, -3, -9 and IL-10. IL-1alpha was significantly higher in OA cartilage and IL-8 in OA synovium. Interestingly, MMP-3, -9, TIMP-1 and all tested cytokines were up-regulated in OA subchondral bone.

DISCUSSION

This study demonstrates pro-inflammatory condition of OA pathology and supports the idea that vascularized subchondral region may increase the synthesis of cytokines and MMPs leading to degradation of adjacent cartilage.

Disease-specific expression patterns of proteases in synovial tissues

To assess whether protease expression patterns can be discriminated according to matrix degradation mechanisms in aseptic prosthesis loosening (APL), rheumatoid arthritis (RA), and osteoarthritis (OA), we immunohistochemically examined the expressions of matrix metalloproteinase-1 and cathepsins B, D, and L in periprosthetic synovial-like interface tissues from 32 patients with failed prosthetic hips, from 29 RA-patients with hip synovial membranes, and from 35 patients with primary OA. Numerical values, calculated for the positivity of each protease, were used to rank the staining patterns, and a multivariate analysis was carried out to examine the discriminant probabilities. As a result of stepwise linear discriminant analyses, the three groups were successfully discriminated with probabilities of 100%, 62.1%, and 77.1%, respectively. Cathepsin L was significantly related to the discrimination of APL from RA and primary OA. Disease-specific protease activation pathways might exist, and cathepsin L can be a key enzyme for APL pathogenesis.

LEVEL OF EVIDENCE

Prognostic study, level III (retrospective study).

Age-related decrease in the activity of collagenase in the femoral head in patients with hip osteoarthritis

The aim of the study was to evaluate the relation between the activity of collagenase in the subchondral bone of the femoral head and the age of patients with hip osteoarthritis. Thirty-two patients were enrolled into the study. The mean age was 66 (range from 37 to 80 years). Bone samples of the femoral head were harvested during total hip replacement. The activity of collagenase was measured through spectrofluorimetry. We found statistically a significant correlation between collagenase activity in the bone and age. The mean activity of collagenase in younger patients (37-68 years) was 64.17 IU/microg. In older patients (69-80 years), the mean collagenase activity was 52.26 IU/microg. In patients with hip osteoarthritis the activity of collagenase in the subchondral bone of the femoral head tended to decrease with an increase in age.

Altered mitochondrial apparent affinity for ADP and impaired function of mitochondrial creatine kinase in gluteus medius of patients with hip osteoarthritis

The cellular energy metabolism in human musculus gluteus medius (MGM) under normal conditions and hip osteoarthritis (OA) was explored. The functions of oxidative phosphorylation and energy transport systems were analyzed in permeabilized (skinned) muscle fibers by oxygraphy, in relation to myosin heavy chain (MHC) isoform distribution profile analyzed by SDS-PAGE, and to creatine kinase (CK) and adenylate kinase (AK) activities measured spectrophotometrically in the intact muscle. The results revealed high apparent Km for ADP in regulation of respiration that decreased after addition of creatine in MGM of traumatic patients (controls). OA was associated with increased sensitivity of mitochondrial respiration to ADP, decreased total activities of AK and CK with major reduction in mi-CK fraction, and attenuated effect of creatine on apparent Km for ADP compared with control group. It also included a complete loss of type II fibers in a subgroup of patients with the severest disease grade. It is concluded that energy metabolism in MGM cells is organized into functional complexes of mitochondria and ATPases. It is suggested that because of degenerative remodeling occurring during development of OA, these complexes become structurally and functionally impaired, which results in increased access of exogenous ADP to mitochondria and dysfunction of CK-phosphotransfer system.

Extracellular superoxide dismutase and oxidant damage in osteoarthritis

OBJECTIVE

To use human cartilage samples and a mouse model of osteoarthritis (OA) to determine whether extracellular superoxide dismutase (EC-SOD) is a constituent of cartilage and to evaluate whether there is a relationship between EC-SOD deficiency and OA.

METHODS

Samples of human cartilage were obtained from femoral heads at the time of joint replacement surgery for OA or femoral neck fracture. Samples of mouse tibial cartilage obtained from STR/ort mice and CBA control mice were compared at 5, 15, and 35 weeks of age. EC-SOD was measured by enzyme-linked immunosorbent assay, Western blotting, and immunohistochemistry techniques. Real-time quantitative reverse transcription-polymerase chain reaction was used to measure messenger RNA for EC-SOD and for endothelial cell, neuronal, and inducible nitric oxide synthases. Nitrotyrosine formation was assayed by Western blotting in mouse cartilage and by fluorescence immunohistochemistry in human cartilage.

RESULTS

Human articular cartilage contained large amounts of EC-SOD (mean +/- SEM 18.8 +/- 3.8 ng/gm wet weight of cartilage). Cartilage from patients with OA had an approximately 4-fold lower level of EC-SOD compared with cartilage from patients with hip fracture. Young STR/ort mice had decreased levels of EC-SOD in tibial cartilage before histologic evidence of disease occurred, as well as significantly more nitrotyrosine formation at all ages studied.

CONCLUSION

EC-SOD, the major scavenger of reactive oxygen species in extracellular spaces, is decreased in humans with OA and in an animal model of OA. Our findings suggest that inadequate control of reactive oxygen species plays a role in the pathophysiology of OA.

Phosphatase-1 and -2A inhibition modulates apoptosis in human osteoarthritis chondrocytes independently of nitric oxide production

OBJECTIVE

To characterise the role of phosphatase-1 and -2A (PP1/2A) in the modulation of apoptosis in human osteoarthritis (OA) chondrocytes.

METHODS

Human OA chondrocytes were isolated from cartilage obtained from the femoral heads of patients undergoing joint replacement surgery. Cell viability was evaluated by MTT assay. Apoptosis was quantified by ELISA, which measures DNA fragmentation. Nitric oxide (NO) production was evaluated by the Greiss method, and inducible nitric oxide synthase (iNOS) protein synthesis was studied by western blotting.

RESULTS

Inhibition of PP1/2A by the specific inhibitor okadaic acid (OKA) dose and time dependently caused a reduction of cell viability (OKA at 50 nmol/l: a reduction to 60% and 43% at 48 and 72 hours, respectively). Genomic DNA from chondrocytes treated with OKA at 50 and 100 nmol/l for 48 hours displayed increased internucleosomal DNA fragmentation by 11 and 13 fields, respectively. Light microscopy and DAPI studies showed that OKA induced DNA condensation and fragmentation, typical of death by apoptosis. The caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK increased cell viability, reduced by OKA at 50 nmol/l to 87% and 73%, respectively. OKA did not increase iNOS protein synthesis or NO production.

CONCLUSION

PP1/2A modulate apoptosis in human OA chondrocytes; this is independent of NO production but dependent on caspases.

Apoptosis--a significant cause of bone cell death in osteonecrosis of the femoral head

Osteonecrosis of the femoral head usually affects young individuals and is responsible for up to 12% of total hip arthroplasties. The underlying pathophysiology of the death of the bone cells remains uncertain. We have investigated nitric oxide mediated apoptosis as a potential mechanism and found that steroid- and alcohol-induced osteonecrosis is accompanied by widespread apoptosis of osteoblasts and osteocytes. Certain drugs or their metabolites may have a direct cytotoxic effect on cancellous bone of the femoral head leading to apoptosis rather than purely necrosis.

Increased apoptosis in human osteoarthritic cartilage corresponds to reduced cell density and expression of caspase-3

OBJECTIVE

Chondrocyte apoptosis has been described in both human and experimentally induced osteoarthritis (OA), but its importance in the etiopathogenesis of OA is uncertain. The aims of this study were to determine the rate of chondrocyte apoptosis using different methods, and to investigate the relationship between this process and cartilage cellularity, expression of proapoptotic molecules, and expression of antiapoptotic molecules in articular cartilage obtained from patients with OA and from nonarthritic controls.

METHODS

We examined the extent of apoptosis in OA and nonarthritic control cartilage using expression of caspase-3, an enzyme that mediates the final stage of cell death by apoptosis, as well as the TUNEL method. We used immunohistochemistry to analyze the expression of a panel of proapoptotic and antiapoptotic molecules that regulate apoptosis in articular cartilage, in order to determine whether the rate of apoptosis is associated with the expression of these molecules.

RESULTS

The median (range) percentage of TUNEL-positive chondrocytes in knee OA cartilage (n = 10 specimens), hip OA cartilage (n = 9), and control cartilage (n = 7) was 3.11 (1.67-3.67), 1.86 (1.22-2.89), and 0.39 (0.00-1.78), respectively. When all cartilage samples were pooled, apoptosis showed a strong inverse correlation with cellularity (r = -0.74, P < 0.0001). The percentage (range) of cells expressing caspase-3 in the 3 groups was 15.70 (7.40-20.50), 15.77 (7.42-20.5), and 7.40 (5.90-8.00), respectively. One-way analysis of variance showed that the differences between groups for both TUNEL-positive cells and expression of caspase-3 were statistically significant (P < 0.0001). There was a significant positive correlation between TUNEL-positive cells and expression of caspase-3 (r = 0.654, P< 0.01).

CONCLUSION

The data suggest that apoptosis is increased, on average, 2-4-fold in OA cartilage. Considering that OA develops over many years, such an increase in the rate of apoptosis in the articular cartilage could play an important role in the disease process.

Changes in the concentration of plasma matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases-1 (TIMP-1) after total joint replacement in patients with arthritis

Matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) have been reported to be associated with arthritis. Total joint replacement results in total resection of cartilage and synovium at the joint. We investigated longitudinal changes in plasma MMP and TIMP after total joint replacement. Eight patients with osteoarthritis (OA) and 15 patients with rheumatoid arthritis (RA) had total knee or total hip replacements. Plasma was collected from all patients before surgery and at 1 week and 6 weeks after surgery. In RA patients the plasma MMP-3 and the MMP-3/TIMP-1 ratio decreased after total joint replacement, whereas CRP and ESR did not change. Therefore, CRP and ESR reflect systemic inflammation; however, plasma MMP-3 and the MMP-3/TIMP-1 ratio may reflect inflammation and/or degeneration of the affected joint.

Inhibition of interleukin-1-stimulated MAP kinases, activating protein-1 (AP-1) and nuclear factor kappa B (NF-kappa B) transcription factors down-regulates matrix metalloproteinase gene expression in articular chondrocytes

Interleukin-1 (IL-1), the main cytokine instigator of cartilage degeneration in arthritis, induces matrix metalloproteinase-3 (MMP-3) and MMP-13 RNA and protein in chondrocytes. The molecular mechanisms of this induction were investigated with specific inhibitors of mitogen-activated protein kinase (MAPK) signaling pathways and activating protein (AP-1) and nuclear factor kappa B (NF-kappa B) transcription factors. IL-1 rapidly induced the activation of extracellular-signal regulated kinase (ERK), protein 38 (p38) and c-Jun N-terminal kinase (JNK) MAPKs in the first-passage human femoral head OA chondrocytes. The ERK-MAPK pathway inhibitor, PD98059, attained 46-53% (MMP-3) and 59-66% (MMP-13) inhibition of RNA induction in human OA and 47-52% (MMP-3) and 69-73% (MMP-13) inhibition in bovine chondrocytes. U0126 conferred 37-77% (MMP-3) and 43-73% (MMP-13) suppression in human and 77-100% (MMP-3) and 96-100% (MMP-13) in bovine chondrocytes. P38 and JNK inhibitor, SB203580 caused 35-37% reduction of MMP-3 and MMP-13 RNA in human and 36-46% (MMP-3) and 60-88% (MMP-13) in bovine chondrocytes. Inhibitor of JNK, AP-1 and NF-kappa B, curcumin, achieved 48-99% suppression of MMP-3 and 45-97% of MMP-13 in human and 8-100% (MMP-3) and 32-100% (MMP-13) in bovine chondrocytes. NF-kappaB inhibitor, pyrrolidine dithiocarbamate yielded 83-84% reduction of MMP-3 and 38-55% for MMP-13 in human chondrocytes. In bovine chondrocytes, the induction decreased by 54-64% for MMP-3 and 74-93% for MMP-13 RNA. These results suggest the involvement of MAPKs, AP-1 and NF-kappa B transcription factors in the IL-1 induction of MMPs in chondrocytes. Inhibition of IL-1 signal transduction by these agents could be useful for reducing cartilage resorption by MMPs in arthritis.

Tissue inhibitor of metalloproteinases-4 (TIMP-4) gene expression is increased in human osteoarthritic femoral head cartilage

Tissue inhibitor of metalloproteinases-4 (TIMP-4), the newest member of the TIMP family, blocks the activities of several matrix metalloproteinases (MMPs) implicated in the arthritic cartilage erosion. By utilizing semi-quantitative RT-PCR, immunoblotting, and immunohistochemistry, we investigated whether the TIMP-4 gene is expressed in human non-arthritic and osteoarthritic (OA) cartilage. Directly analyzed femoral head cartilage showed TIMP-4 RNA expression in 2 of 9 non-arthritic and 12 of 14 OA patients. Femoral head cartilage from 6 of 9 OA patients had elevated TIMP-4 protein compared to the low-level expression in 3 of 8 non-arthritic controls. In most patients, there was correlation between TIMP-4 RNA and protein expression. TIMP-4 protein was also detected immunohistochemically in the upper zone of OA cartilage. The widespread TIMP-4 RNA and protein expression and augmentation in femoral OA cartilage suggests its important role in joint tissue remodeling and pathogenesis of OA. Increased TIMP levels in arthritic cartilage may not be a sufficiently effective defense against cartilage resorption by excessive multiple MMPs and aggrecanases.

The relative importance of cysteine peptidases in osteoarthritis

OBJECTIVE

To assess the activity of cysteine peptidases in cultured human articular chondrocytes as well as in osteoarthritic (OA) cartilage and subchondral bone, and to interpret their relative importance in cartilage destruction and remodeling of the subchondral region.

METHODS

Intracellular and secreted cysteine peptidase activity was measured in chondrocytes using fluorimetric assays, and enzymes were immunolocalized using monospecific antibodies. Enzyme histochemistry in normal and OA femoral heads was used to characterize enzymatic activity in full thickness samples containing cartilage and subchondral bone. The zonal distribution of cathepsin activity was measured in tissue slices of normal and OA femoral heads cut parallel to the joint surface, using fluorogenic substrates.

RESULTS

Cathepsins B and L were localized by immunohistochemistry with lysosome-like structures in dedifferentiated chondrocytes. Free cysteine peptidase activity (i.e., not requiring prior activation), secreted and intracellularly stored by chondrocytes, was due to cathepsin B, while cathepsin L contributed a minor fraction of the total activity, and was seen only after activation at acidic pH. Histochemistry and activity measurements confirmed cathepsin B as the major, active cysteine peptidase in OA cartilage, particularly at sites where matrix neosynthesis took place. However, free cathepsin L and/or cathepsin K activity was found subchondrally in association with cathepsin B in osteophytes, in zones undergoing bone remodeling, and at sites of inflammation.

CONCLUSION

Cathepsin B, not cathepsin L or cathepsin K, is a candidate for articular cartilage catabolism in OA. While cathepsin K is the major osteoclastic cysteine peptidase, cathepsin L and cathepsin B may also participate in the remodeling processes of bone as well as in bone erosion by inflammatory cells.

Synovial fluid cartilage metabolism marker concentrations in osteonecrosis of the femoral head compared with osteoarthrosis of the hip

OBJECTIVE

Biochemical aspects of the etiology of articular cartilage degeneration in osteonecrosis of the femoral head have not been investigated extensively. We analyzed biochemical conditions in the hip joint cavity, regarding articular cartilage turnover in osteonecrosis of the femoral head (ONFH).

METHODS

Cartilage metabolism markers in synovial fluid were measured. Synovial fluid (SF) samples were collected from 19 ONFH cases and 17 control hips with osteoarthrosis (OA). Concentrations of carboxy-terminal type II procollagen peptide (pCOL-II-C), matrix metalloproteinase-3 (MMP-3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured. In addition, concentrations of unsaturated disaccharides of hyaluronic acid (delta di-HA), chondroitin 4-sulfate (delta di-4S), and chondroitin 6-sulfate (delta di-6S) in SF were measured by high performance liquid chromatography.

RESULTS

The mean SF concentration of pCOL-II-C was higher on ONFH than in OA. The mean SF MMP-3 level was higher in ONFH than in OA, while the mean SF TIMP-1 level was the same in the 2 groups. The SF concentration of delta di-HA and the delta di-6S/delta di-4S ratio were higher in ONFH than in OA.

CONCLUSION

Higher concentrations of cartilage metabolism markers in ONFH compared with OA SF suggest elevated cartilage turnover in the former disease.

Oral administration of doxycycline reduces collagenase and gelatinase activities in extracts of human osteoarthritic cartilage

OBJECTIVE

To determine whether oral administration of doxycycline in clinically relevant doses will suppress activities of collagenase and gelatinase in extracts of human osteoarthritic (OA) cartilage.

METHODS

Femoral heads were obtained from 21 patients undergoing arthroplasty for endstage hip OA. Activities of collagenase and gelatinase were measured in extracts of the OA cartilage from patients who received doxycycline, 100 mg bid or qam for 5 days before surgery (n = 5 and n = 6, respectively), 200 mg as a single dose 3 days before surgery (n = 4); or no doxycycline (n = 6).

RESULTS

Five days of doxycycline treatment, in a dose of either 100 mg bid or 100 mg qam, inhibited gelatinase activity in the cartilage extracts (p = 0.003, 0.008, respectively). The bid dose also inhibited collagenase activity (p = 0.002), but inhibition of collagenase with 100 mg qam did not quite reach statistical significance (p = 0.055), in comparison with the values for the untreated OA controls. The single 200 mg dose, given 3 days before procurement of the cartilage, was ineffective in inhibiting metalloproteinase activity.

CONCLUSION

Oral administration of doxycycline significantly inhibited collagenase and gelatinase activity in human OA cartilage. The effective dose is likely to be well tolerated during chronic administration, e.g., in a clinical trial to assess the potential of the drug to modify cartilage breakdown in OA.

[Expression of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in joint tissues of rapidly destructive coxarthropathy (RDC), analyzed by immunohistochemical study]

OBJECTIVE

Rapidly destructive coxarthropathy (RDC) is characterized by rapid destruction of hip joints, but its pathogenetic mechanism is still obscure. Matrix metalloproteinases (MMPs) are possibly one of the candidates concerning with this mechanism. We attempted histochemical investigation to demonstrate MMPs and tissue inhibitor of metalloproteinases (TIMPs) in joint tissues obtained from RDC patients to clarify their roles in the destruction mechanism.

MATERIALS AND METHODS

Joint tissues including synovia and cartilage-bone tissues were obtained from RDC patients at total hip replacement (THR). After fixation with 4% paraformaldehyde, cartilage-bone tissues were partly decalcified. We performed histochemical study for paraffin sections of these tissues by using avidin-biotin method. Antibodies used in this study were monoclonal antibodies to MMP-1, MMP-2, MMP-7, MMP-8, MMP-9, TIMP-1, TIMP-2 and polyclonal antibody to MMP-3.

RESULTS

Histological feature of RDC was severe destruction of cartilage and bone by invasion of non-specific granulation tissues composed of many small vessels, macrophages and fibroblastic cells. At the same time, RDC showed apparently fewer lymphocytic cells in these granulation tissues compare with rheumatoid arthritis. MMP-2 and MMP-9 were expressed most demonstrably in synovia and destructive regions of femoral heads, especially in osteoclasts, macrophages, and fibroblastic cells, while MMP-1, MMP-3, were slightly expressed only in the superficial layer of synovia in limited cases. MMP-8, usually contained in neutrophils, was not present in RDC. On the other hand TIMP-1 and TIMP-2 were presented throughout the synovia and destructive regions of femoral heads including fibroblastic cells, macrophages, osteoblasts and osteocytes.

CONCLUSION

Immunohistochemical study revealed obvious presence of MMP-2 and MMP-9 in synovia and destructive regions of femoral heads in RDC. Those evidence suggest that MMP-2 and MMP-9 share very important role in the destructive mechanism of RDC, possibly under imbalance between TIMPs.

Neuropeptide-converting enzymes in cerebrospinal fluid: activities increased in pain from herniated lumbar dis, but not from coxarthrosis

We measured activities of dynorphin-converting enzyme (DCE), substance P endopeptidase (SPE) and angiotensin-converting enzyme (ACE) in cerebrospinal fluid (CSF) in 13 patients with rhizopathic pain from an herniated lumbar disc, in 9 patients with pain from coxarthrosis and in 11 control patients without pain. In the patients with disc hernia and coxarthrosis, another sample of CSF was analyzed 3-12 months after treatment, when pain had subsided. The DCE activity in the patients was higher than that in both the control patients and the patients with pain from coxarthrosis (nociceptive pain). Similarly, the activity of SPE was lower in the patients with herniated lumbar disc than in controls and in the patients with coxarthrosis. After treatment, the difference in activity compared to controls was lower, but still significant in patients with herniated discs. The ACE activity did not differ from controls in patients with ischialgia, while it was increased in patients with coxarthrosis. This increase also remained after arthroplasty with pain relief. In conclusion, measurements of neuropeptides may be useful for evaluating neuropathic pain.

[Serum phospholipase A2 activity in osteoarthritis]

Serum phospholipase A2 activity in 67 osteoarthritis patients and 17 controls was determined using a radiolabeled specific substrate. Serum phospholipase A2 activity was significantly higher in osteoarthritis patients (115 +/- 73.6 dpm/h/ml) than in controls (45 +/- 25 dpm/h/ml) (p = 0.002). In 41 osteoarthritis patients, serum phospholipase A2 activity was unrelated to age, time since onset of osteoarthritis symptoms, duration of morning stiffness, Lequesne's index, roentgenographic stage of osteoarthritis, number of joints with osteoarthritis, erythrocyte sedimentation rate, or serum C-reactive protein levels. In 12 osteoarthritis patients who were evaluated twice at a mean interval of 46 days, changes in serum phospholipase A2 activity were unrelated to changes in Lequesne's index. Blind evaluation of long-term joint space loss was performed in 14 patients; serum phospholipase A2 activity increased only in those patients with progressive joint space loss, but the difference was not statistically significant as compared with the controls. These data suggest that serum phospholipase A2 activity is not useful in practice as a marker for osteoarthritis.

In vitro effect of nonsteroidal antiinflammatory drugs on proteoglycanase and collagenase activity in human osteoarthritic cartilage

The effects of several nonsteroidal antiinflammatory drugs, used at concentrations achievable in synovial fluid, on human osteoarthritic (OA) cartilage metallo-protease activity in vitro was studied. Acetaminophen and ketoprofen had no effect; sodium salicylate, indomethacin, and diclofenac slightly decreased proteoglycanase activity. Piroxicam and tenoxicam suppressed proteoglycanase activity by 48.2% and 68.3%, respectively, and suppressed collagenase activity by 19.1% and 36.8%, respectively. Use of these NSAIDs may help to decrease cartilage catabolism in patients with OA.

[Effects of naproxen (naprosyne) on the metabolism of arthrotic cartilage in man in vivo]

Degradative enzyme (proteoglycanase and collagenase) as well as proteoglycan synthesis enzyme (glycosyl-transferase) activity was studied in osteoarthritic fibrillated cartilage. Proteoglycanase activity was significantly lower in 10 patients with hip osteoarthritis treated with Naproxen (1 g/daily for 4 weeks) than in 10 patients treated with acetaminophen. Synthesis enzyme activity was similar in both groups. The results which confirm in vitro studies suggest that naproxen has not toxic effect on human osteoarthritic cartilage and could rather be beneficial.

Type XI collagen-degrading activity in human osteoarthritic cartilage

Homogenates of 6 samples of human osteoarthritic cartilage were shown to degrade exogenous type XI collagen. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the cleavage products generated by each homogenate were similar, and they were identical to those obtained by cleavage of the substrate with purified gelatinase. Enzyme activity, which was inhibited by EDTA, was greater in extracts of fibrillated osteoarthritic cartilage than in extracts of grossly normal cartilage from the same joint or in extracts of cartilage from joints with osteonecrosis. Activation with APMA enhanced digestion, but breakdown was apparent in extracts of fibrillated osteoarthritic cartilage even without APMA. Enzymatic degradation of type XI collagen could play a significant role in the turnover of articular cartilage in health and disease states.

[Effects of non-steroidal anti-inflammatory drugs on the enzymatic degradation of osteoarthritic cartilage]

The proteoglycannasic and collagenolytic activity the fissured, osteoarthritic human cartilage has been studied in vitro, using proteoglycannases and collagen type II respectively as marked substrates. The effect of various NSAIDs, used at a concentration corresponding to that of the synovial fluid, on these enzymatic activities has been measured in vitro. Naproxen decreases in a significant and dose-dependent way the enzymatic degradation of the cartilage, but only an inhibition of the proteoglycannase can be hoped for in vivo. Not all NSAIDs seem to have inhibitory effects on the enzymatic degradation of the osteoarthritic cartilage.