Matrix metalloproteinases in arthritic disease

Sclareol exerts anti-osteoarthritic activities in interleukin-1β-induced rabbit chondrocytes and a rabbit osteoarthritis model

Sclareol is a natural product initially isolated form Salvia sclarea which possesses immune-regulation and anti-inflammatory activities. However, the anti-osteoarthritic properties of sclareol have not been investigated. The present study is aimed at evaluating the potential effects of sclareol in interleukin-1β (IL-1β)-induced rabbit chondrocytes as well as an experimental rabbit knee osteoarthritis model induced by anterior cruciate ligament transection (ACLT). Cultured rabbit chondrocytes were pretreated with 1, 5 and 10 μg/mL sclareol for 1 h and followed by stimulation of IL-1β (10 ng/mL) for 24 h. Gene expression of matrix metalloproteinase-1 (MMP-1), MMP-3, MMP-13, tissue inhibitors of metalloproteinase-1 (TIMP-1), inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 was determined by quantitative real-time polymerase chain reaction (qRT-PCR). MMP-3, TIMP-1, iNOS and COX-2 proteins were measured by Western blotting. Enzyme-linked immunosorbent assay (ELISA) was applied for nitric oxide (NO) and prostaglandin E2 (PGE2) assessment. For the in vivo study, rabbits received six weekly 0.3 mL sclareol (10 μg/mL) intra-articular injections in the knees four weeks after ACLT surgery. Cartilage was harvested for measurement of MMP-1, MMP-3, MMP-13, TIMP-1, iNOS and COX-2 by qRT-PCR, while femoral condyles were used for histological evaluation. The in vitro results we obtained showed that sclareol inhibited the MMPs, iNOS and COX-2 expression on mRNA and protein levels, while increased the TIMP-1 expression. And over-production of NO and PGE2 was also suppressed. For the in vivo study, both qRT-PCR results and histological evaluation confirmed that sclareol ameliorated cartilage degradation. Hence, we speculated that sclareol may be an ideal approach for treating osteoarthritis.

Altered proteolytic activity and expression of MMPs and aggrecanases and their inhibitors in Kashin-Beck disease

Kashin-Beck disease (KBD) is a chronic, deforming endemic osteoarticular disease with altered metabolism of the cartilage matrix. Matrix metalloproteinases (MMPs), aggrecanases (ATAMTSs), and their inhibitors (TIMPs) play important roles in cartilage formation and matrix degradation. This study investigated these proteases and inhibitors in young KBD cartilage. The percentages of chondrocytes staining for MMP-1/-13 and MMP-generated DIPEN neoepitope, aggrecanase-generated ITEGE neoepitope in aggrecan in KBD patients were significantly higher than in controls. However, TIMP-1 was significantly less numerous than in controls in the superficial and middle zones of KBD samples, the percentage of chondrocytes staining for the TIMP-2 was significantly higher than in controls. Staining for MMP-1/-13 and, TIMP-1/-2 in KBD patients was prominent in the superficial zone and the middle zone of articular cartilage. Staining for ITEGE and DIPEN neoepitopes in KBD samples was prominent in the superficial zone and the middle zone of articular cartilage. The strongest staining for the MMP and aggrecanase-generated neoepitopes was adjacent to areas of chondronecrosis. These results indicated that KBD cartilage destruction depends on collagen- and aggrecan-degrading proteases such as collagenases (MMP-1/-13), as well as aggrecanases. Increased TIMP-2 level adjacent to necrotic areas suggest that attempted repair mechanism are also activated.

A quicker degradation rate is yielded by a novel kind of transgenic silk fibroin consisting of shortened silk fibroin heavy chains fused with matrix metalloproteinase cleavage sites

Degradation performance of silk fibroin is an important property for its medical applications. Herein we constructed a shortened silk fibroin heavy chain protein fused with a matrix metalloproteinase cleavage site (SSFH-MMP) along with a glutathione S-transferase tag ahead. The digestion assay shows it can be cut by matrix metalloproteinase-2 (MMP-2) at its MMP cleavage site. Furthermore, we introduced the SSFH-MMP into silk fibroin by genetic modification of silkworms in order to increase the degradation rate of the silk fibroin. After acquisition of a race of transgenic silkworms with the coding sequence of the MMP cleavage site in their genomic DNA, we tested some properties of their silk fibroin designated TSF-MMP. The results show that the TSF-MMP has MMP cleavage sites and yields a quicker degradation rate during dilution in MMP-2 enzyme buffer or implantation into tumor tissues compared with that of normal silk fibroin. Moreover, the TSF-MMP is in vitro non-toxic to human bone marrow mesenchymal stem cells (hBM-MSCs) indicating that the TSF-MMP may become a biomaterial with a quicker degradation rate for its medical applications.

Matrix Degradative Enzymes and Their Inhibitors during Annular Inflammation: Initial Step of Symptomatic Intervertebral Disc Degeneration

Objective

Symptomatic disc degeneration develops from inflammatory reactions in the annulus fibrosus (AF). Although inflammatory mediators during annular inflammation have been studied, the roles of matrix metalloproteinases (MMPs) and their inhibitors have not been fully elucidated. In this study, we evaluated the production of MMPs and tissue inhibitors of metalloproteinase (TIMPs) during annular inflammation using an in vitro co-culture system. We also examined the effect of notochordal cells on annular inflammation.

Methods

Human AF (hAF) pellet was co-cultured for 48 hours with phorbol myristate acetate-stimulated macrophage-like THP-1 cells. hAF pellet and conditioned media (CM) from co-cultured cells were assayed for MMPs, TIMPs, and insulin-like growth factor (IGF)-1 levels using real-time reverse-transcriptase polymerase chain reaction and enzyem-linked immunosorbent assay. To evaluate whether notochordal cells affected MMPs or TIMPs production on annular inflammation, hAF co-cultured with notochordal cells from adult New Zealand White rabbits, were assayed.

Results

MMP-1, -3, -9; and TIMP-1 levels were significantly increased in CM of hAF co-cultured with macrophage-like cells compared with hAF alone, whereas TIMP-2 and IGF-1 levels were significantly decreased (p<0.05). After macrophage exposure, hAF produced significantly more MMP-1 and -3 and less TIMP-1 and -2. Interleukin-1β stimulation enhanced MMP-1 and -3 levels, and significantly diminished TIMP-2 levels. Co-culturing with rabbit notochordal cells did not significantly influence MMPs and TIMPs production or COL1A2 gene expression.

Conclusion

Our results indicate that macrophage-like cells evoke annular degeneration through the regulation of major degradative enzymes and their inhibitors, produced by hAF, suggesting that the selective regulation of these enzymes provides future targets for symptomatic disc degeneration therapy.

Chemopreventive effects of a curcumin-like diarylpentanoid [2,6-bis(2,5-dimethoxybenzylidene)cyclohexanone] in cellular targets of rheumatoid arthritis in vitro

AIM

Synovial fibroblast has emerged as a potential cellular target in progressive joint destruction in rheumatoid arthritis development. In this study, BDMC33 (2,6-bis[2,5-dimethoxybenzylidene]cyclohexanone), a curcumin analogue with enhanced anti-inflammatory activity has been synthesized and the potency of BDMC33 on molecular and cellular basis of synovial fibroblasts (SF) were evaluated in vitro.

METHODS

Synovial fibroblast cells (HIG-82) were cultured in vitro and induced by phorbol-12-myristate acetate (PMA) to stimulate the expression of matrix metalloproteinase (MMPs) and pro-inflammatory cytokines. The protective effects of BDMC33 were evaluated toward MMP activities, pro-inflammatory cytokine expression and nuclear factor kappa-B (NF-κB) activation by using various bioassay methods, including zymography, Western blotting, reverse transcription polymerase chain reaction, immunofluorescense microscopy and electrophoretic mobility shift assay.

RESULTS

The results showed that BDMC33 significantly inhibited the pro-gelatinase B (pro-MMP-9) and collagenase activities via suppression of MMP-1 in activated SF. In addition, BDMC33 strongly suppressed MMP-3 gene expression as well as inhibited COX-2 and IL-6 pro-inflammatory gene expression. We also demonstrated that BDMC33 abolished the p65 NF-κB nuclear translocation and NF-κB DNA binding activity in PMA-stimulated SF.

CONCLUSIONS

BDMC33 represents an effective chemopreventive agent and could be used as a promising lead compound for further development of rheumatoid arthritis therapeutic intervention.

Immunolocalization of MMP-2 and MMP-9 in human rheumatoid synovium

Matrix metalloproteinase (MMP)-2 and MMP-9, two important members of the matrix metalloproteinase family, have been shown critical contributions in intra-tumor angiogenesis and invasion of tumor progression, and they might also play important roles in the angiogenesis as well as the pannus formation of rheumatoid arthritis (RA). In the present study, we used the immunohistochemistry, the immunofluorescence staining and the con-focal scanning methods to characterize the immunolocalization of MMP-2 and MMP-9 in RA synovium tissues. Our results showed that both MMP-2 and MMP-9 immunostaining could be found in synoviocytes and vascular endothelial cells. Moreover, our con-focal scanning also showed that MMP-2 could be found in infiltrating CD14(+) monocytes and CD68(+) macrophages, and MMP-9 could be found in infiltrating CD68(+) macrophages in RA synovium tissues, while weak or negative staining of these two MMPs could be found in infiltrating CD20(+)B cells and CD3(+)T cells in RA synovium. Thus, our finding suggests that both MMP-2 and MMP-9 expressed by synoviocytes as well as certain infiltrating immune cells role importantly in the angiogenesis in RA progression.

Differential proteomic analysis of synovial fluid from rheumatoid arthritis and osteoarthritis patients

Background

Rheumatoid arthritis and osteoarthritis are two common musculoskeletal disorders that affect the joints. Despite high prevalence rates, etiological factors involved in these disorders remain largely unknown. Dissecting the molecular aspects of these disorders will significantly contribute to improving their diagnosis and clinical management. In order to identify proteins that are differentially expressed between these two conditions, a quantitative proteomic profiling of synovial fluid obtained from rheumatoid arthritis and osteoarthritis patients was carried out by using iTRAQ labeling followed by high resolution mass spectrometry analysis.

Results

We have identified 575 proteins out of which 135 proteins were found to be differentially expressed by ≥3-fold in the synovial fluid of rheumatoid arthritis and osteoarthritis patients. Proteins not previously reported to be associated with rheumatoid arthritis including, coronin-1A (CORO1A), fibrinogen like-2 (FGL2), and macrophage capping protein (CAPG) were found to be upregulated in rheumatoid arthritis. Proteins such as CD5 molecule-like protein (CD5L), soluble scavenger receptor cysteine-rich domain-containing protein (SSC5D), and TTK protein kinase (TTK) were found to be upregulated in the synovial fluid of osteoarthritis patients. We confirmed the upregulation of CAPG in rheumatoid arthritis synovial fluid by multiple reaction monitoring assay as well as by Western blot. Pathway analysis of differentially expressed proteins revealed a significant enrichment of genes involved in glycolytic pathway in rheumatoid arthritis.

Conclusions

We report here the largest identification of proteins from the synovial fluid of rheumatoid arthritis and osteoarthritis patients using a quantitative proteomics approach. The novel proteins identified from our study needs to be explored further for their role in the disease pathogenesis of rheumatoid arthritis and osteoarthritis.

Sartaj Ahmad and Raja Sekhar Nirujogi contributed equally to this article.

The anti-inflammatory and matrix restorative mechanisms of platelet-rich plasma in osteoarthritis

BACKGROUND

Intra-articular (IA) treatment with platelet-rich plasma (PRP) for osteoarthritis (OA) results in improved patient-reported pain and function scores.

PURPOSE

To measure the effects of PRP and high molecular weight hyaluronan (HA) on the expression of anabolic and catabolic genes and on the secretion of nociceptive and inflammatory mediators from OA cartilage and synoviocytes.

STUDY DESIGN

Controlled laboratory study.

METHODS

Synovium and cartilage harvested from patients undergoing total knee arthroplasty were co-cultured with media of PRP or HA. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β were measured in the media by enzyme-linked immunosorbent assay. Hyaluronan synthase-2 (HAS-2), matrix metalloproteinase-1 (MMP-1), MMP-13, and TNF-α genes were measured in synoviocytes by reverse transcription polymerase chain reaction (RT-PCR). Collagen type I α1 (COL1A1), COL2A1, aggrecan (ACAN), and MMP-13 gene expression were measured in cartilage by quantitative RT-PCR.

RESULTS

Media TNF-α concentration was decreased in PRP and HA compared with control cultures (PRP = 6.94 pg/mL, HA = 6.39 pg/mL, control = 9.70 pg/mL; P ≤ .05). Media IL-6 concentration was decreased in HA compared with PRP and control (HA = 5027 pg/mL, PRP = 5899 pg/mL, control = 5613 pg/mL; P ≤ .05). Media IL-1β was below detectable concentrations (<0.1 pg/mL) in all samples. Synoviocyte MMP-13 expression was decreased in PRP compared with HA and control (PRP = 10.1, HA = 12.8, control = 13.5; P ≤ .05). Synoviocyte HAS-2 expression was increased in PRP compared with HA and control (PRP = 12.1, HA = 9.8, control = 8.7; P ≤ .05). Cartilage ACAN expression was increased in PRP compared with HA, but neither was different from control (PRP = 8.8, HA = 7.7, control = 7.6; P ≤ .05); COL1A1 expression was increased in HA compared with PRP, but neither was different from control (PRP = 14.9, HA = 13.5, control = 12.9; P ≤ .05). Neither platelet nor leukocyte concentration had a significant effect on outcome measurements (gene or protein expression data) in cartilage or synoviocytes (P > .05).

CONCLUSION

Both PRP and HA treatments of OA joint tissues result in decreased catabolism, but PRP treatment also resulted in a significant reduction of MMP-13, an increase in HAS-2 expression in synoviocytes, and an increase in cartilage synthetic activity compared with HA. These results indicate that PRP acts to stimulate endogenous HA production and decrease cartilage catabolism. Platelet-rich plasma showed similar effects as HA in the suppression of inflammatory mediator concentration and expression of their genes in synoviocytes and cartilage.

CLINICAL RELEVANCE

The antinociceptive and anti-inflammatory activities of PRP support its use in OA joints to reduce pain and modulate the disease process. This study supports further clinical investigations of IA PRP for the treatment of OA.

Salivary proteomics in bisphosphonate-related osteonecrosis of the jaw

OBJECTIVE

The objective of this study was to identify differentially expressed salivary proteins in bisphosphonate-related osteonecrosis of the jaw (BRONJ) patients that could serve as biomarkers for BRONJ diagnosis.

SUBJECTS AND METHODS

Whole saliva obtained from 20 BRONJ patients and 20 controls were pooled within groups. The samples were analyzed using iTRAQ-labeled two-dimensional liquid chromatography-tandem mass spectrometry.

RESULTS

Overall, 1340 proteins were identified. Of these, biomarker candidates were selected based on P-value (<0.001), changes in protein expression (≥1.5-fold increase or decrease), and unique peptides identified (≥2). Three comparisons made between BRONJ and control patients identified 200 proteins to be differentially expressed in BRONJ patients. A majority of these proteins were predicted to have a role in drug metabolism and immunological and dermatological diseases. Of all the differentially expressed proteins, we selected metalloproteinase-9 and desmoplakin for further validation. Immunoassays confirmed increased expression of metalloproteinase-9 in individual saliva (P = 0.048) and serum samples (P = 0.05) of BRONJ patients. Desmoplakin was undetectable in saliva. However, desmoplakin levels tended to be lower in BRONJ serum than controls (P = 0.157).

CONCLUSIONS

Multiple pathological reactions are involved in BRONJ development. One or more proteins identified by this study may prove to be useful biomarkers for BRONJ diagnosis. The role of metalloproteinase-9 and desmoplakin in BRONJ requires further investigation.

Mitochondrial respiratory chain dysfunction modulates metalloproteases -1, -3 and -13 in human normal chondrocytes in culture

BACKGROUND

Mitochondrion has an important role in the osteoarthritis (OA) pathology. We have previously demonstrated that the alteration of the mitochondrial respiratory chain (MRC) contributes to the inflammatory response of the chondrocyte. However its implication in the process of cartilage destruction is not well understood yet. In this study we have investigated the relationship between the MRC dysfunction and the regulation of metalloproteases (MMPs) in human normal chondrocytes in culture.

METHODS

Human normal chondrocytes were isolated from human knees obtained form autopsies of donors without previous history of rheumatic disease. Rotenone, 3-Nitropropionic acid (NPA), Antimycin A (AA), Sodium azide and Oligomycin were used to inhibit the activity of the mitochondrial complexes I, II, III, IV and V respectively. The mRNA expression of MMPs -1, -3 and -13 was studied by real time PCR. The intracellular presence of MMP proteins was evaluated by western blot. The liberation of these proteins to the extracellular media was evaluated by ELISA. The presence of proteoglycans in tissue was performed with tolouidin blue and safranin/fast green. Immunohistochemistry was used for evaluating MMPs on tissue.

RESULTS

Firstly, cells were treated with the inhibitors of the MRC for 24 hours and mRNA expression was evaluated. An up regulation of MMP-1 and -3 mRNA levels was observed after the treatment with Oligomycin 5 and 100 μg/ml (inhibitor of the complex V) for 24 hours. MMP-13 mRNA expression was reduced after the incubation with AA 20 and 60 μg/ml (inhibitor of complex III) and Oligomycin. Results were validated at protein level observing an increase in the intracellular levels of MMP-1 and -3 after Oligomycin 25 μg/ml stimulation [(15.20±8.46 and 4.59±1.83 vs. basal=1, respectively (n=4; *P<0.05)]. However, AA and Oligomycin reduced the intracellular levels of the MMP-13 protein (0.70±0.16 and 0.3±0.24, respectively vs. basal=1). In order to know whether the MRC dysfunction had an effect on the liberation of MMPs, their levels were evaluated in the supernatants. After 36 hours of stimulation, values were: MMP-1=18.06±10.35 with Oligomycin 25 μg/ml vs. basal=1, and MMP-3=8.49±4.32 with Oligomycin 5 μg/ml vs. basal=1 (n=5; *P<0.05). MMP-13 levels in the supernatants were reduced after AA 60 μg/ml treatment (0.50±0.13 vs. basal=1) and Oligomycin 25 μg/ml (0.41±0.14 vs. basal=1); (n=5; *P<0.05). The treatment of explants with Oligomycin, showed an increase in the positivity of MMP-1 and -3. Explants stimulated with AA or Oligomycin revealed a decrease in MMP-13 expression. Proteoglycan staining demonstrated a reduction of proteoglycan levels in the tissues treated with Oligomycin.

CONCLUSIONS

These results reveal that MRC dysfunction modulates the MMPs expression in human normal chondrocytes demonstrating its role in the regulation of the cartilage destruction.

Association of biomarkers of inflammation, cartilage and bone turnover with gender, disease activity, radiological damage and sacroiliitis by magnetic resonance imaging in patients with early spondyloarthritis

To assess the association between biomarkers of inflammation, cartilage and bone turnover with gender, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Spondylitis Disease Activity Score (ASDAS) and bone marrow oedema in resonance magnetic imaging (MRI) of sacroiliac joints (SIJs) and radiological damage in early spondyloarthritis (SpA). Cross-sectional study of 60 patients (56.7 % females; mean age, 32.4 years) with early SpA. Sociodemographic data, clinical features, serum matrix metalloproteinase 3 (MMP-3), high sensitivity C-reactive protein (hsCRP), C-terminal cross-linking telopeptides of type I collagen (CTX-I) and urinary deoxypyridinoline, ASDAS, BASDAI, BASFI, BASRI and MRI of the SIJs were collected. The mean (SD) disease duration was 12.4 (6.8 months). Twenty-two (68.7 %) of the 32 patients had active sacroiliitis by MRI. MMP-3 and CTX I correlated with swollen joint (r = 0.515, r = 0.386, p = 0.01). hsCRP correlated with ESR (r = 0.303, p = 0.05), with CRP (r = 0.455, p = 0.01) and with total BASRI (r = 0.95, p = 0.05). Biomarkers were unrelated with the rest of variables. Levels of MMP-3 (44.3 ± 52.4 vs 24.7 ± 33.4, p < 0.05) and CTX-I (0.53 ± 0.45 vs 0.24 ± 0.38; p < 0.05) were higher in men. Our study shows that CTX-I and MMP-3 are a marker of peripheral disease activity in early SpA. Male gender had higher levels of CTX-I and MMP-3, which may indicate higher disease activity. Higher hsCRP levels trended towards correlation with more baseline radiographic damage. Therefore, these biomarkers may help identify a subgroup of patients who will need closer monitoring and more intensive treatment.

CIINE Reflects Collagenase-Specific CII Breakdown in Cartilage Explant and Whole Body of Canine

To evaluate collagenase inhibitors for the treatment of osteoarthritis and to correlate them with clinical pathology, canine cartilage explant and anterior cruciate ligament transection (ACLT) models were examined by quantifying the CII neoepitope (CIINE). This peptide is a putative marker for collagenase-specific type II collagen (CII) degradation, which is a critical step in osteoarthritis pathology.

The concentration of CIINE in supernatants of canine cartilage explants showed increase upon IL-1β—stimulation and collagenase inhibitors suppressed this elevation of CIINE. In the canine ACLT model, levels of CIINE in urine (uCIINE) increased as lesions of knee joint cartilage developed and decreased in response to collagenase inhibitors.

Our results suggest that CIINE reflects collagenase-specific CII degradation in canine explants and whole bodies. It is anticipated that these data will establish a tool for clarifying and bridging the efficacy and mechanism of collagenase inhibitors at the preclinical stage of drug discovery.

Potent inhibitors precise to S1' loop of MMP-13, a crucial target for osteoarthritis

Matrix metalloproteinase-13 (MMP-13) is the primary MMP involved in cartilage degradation through its particular ability to cleave type-II collagen. This protein is expressed by chondrocytes and synovial cells in human osteoarthritis and rheumatoid arthritis; hence, it is an attractive target for the treatment of arthritic diseases. Currently available inhibitors lack specificity for metalloproteinase because of a common Zn binding site in MMPs; thus, there is a need to identify selective MMP-13 inhibitors for osteoarthritis therapy. Because selectivity is the major concern, both ligand-based and protein-based pharmacophore methodologies were used to identity potent and selective MMP-13 inhibitors. Different hypotheses were validated, and the best hypothesis was used to screen Zinc (natural and chemical) databases to seek novel scaffolds as MMP-13 inhibitors. The identified hits were validated using different strategies, such as Glide Standard precision, extra precision, E-model energies and receiver operating curve (ROC). In addition, potent inhibitors were selected based on two criteria: a similar binding mode as that of the active site PB3 crystal ligand and crucial amino acid interactions that are catalytically important for the function of MMP-13. The candidate potent inhibitors ZINC 02535232, ZINC 08399795, ZINC 12419118 and ZINC 00624580 nearly reproduced the H-bond interactions formed in the crystal structure of 1XUC with reasonable RMSD values exhibiting a novel interaction pattern that was not previously observed in MMP-13 inhibitors. The identified potent hits with diverse chemical scaffolds may be useful in designing new MMP-13 inhibitors.

High disease activity in ankylosing spondylitis is associated with increased serum sclerostin level and decreased wingless protein-3a signaling but is not linked with greater structural damage

Background

Clinical activity of ankylosing spondylitis (AS) predicts the natural course of the disease and the response to treatment. Several molecules are involved in new bone formation resulting in structural damage in patients with AS. However, the link between the clinical and molecular phenomena has not yet been fully established. The aim of the study was to investigate the relation between markers of bone remodeling and inflammation with clinical activity and structural damage in AS.

Methods

We assessed the serum levels of sclerostin, Dickkopf-1 protein, Wingless protein-3a, bone morphogenic protein-7, matrix metalloproteinase-3, osteoprotegerin, bone alkaline phosphatase and inflammatory markers in 50 AS patients with high disease activity (BASDAI ≥ 4), 28 with low disease activity (BASDAI <4), and 23 healthy controls. Cervical and lumbar spine x-rays were performed in 46 patients to measure structural damage (mSASSS).

Results

Sclerostin level was significantly greater in high disease activity patients than in controls. Wingless protein-3a and Dikkopf-1 protein levels were significantly lower in high activity group compared to low activity group and controls. Negative correlation was found between sclerostin and Dikkopf-1 protein in high activity group (R = −0.28, P = 0.048). The median mSASSS values were not different between patient groups.

Conclusions

Higher disease activity in AS may not be per se associated with greater new bone formation.

The chondroprotective effects of dehydroepiandrosterone probably exerted by its conversion to estradiol

The sex hormone precursor dehydroepiandrosterone (DHEA), which can be converted into estradiol by the enzyme aromatase, has a protective role against osteoarthritis (OA). To determine whether the protective effects of DHEA are dependent on its conversion to estradiol, the aromatase inhibitor letrozole and/or the estrogen receptor inhibitor fulvestrant were administered in the presence of DHEA in both interleukin 1β (IL-1β)-induced rabbit chondrocytes and a rabbit anterior cruciate ligament transaction (ACLT) model of OA. Expression levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase-1 (TIMP-1) were used to monitor these effects. Expression of MMP-3 and MMP-13 increased in both DHEA-treated chondrocytes and cartilage in the presence of letrozole and/or fulvestrant, while the expression of TIMP-1 and collagen type II (Col-II) decreased. Our findings suggest that the effects of DHEA may be mediated by its conversion to estradiol.

Inhibition of matrix metalloproteinases and inducible nitric oxide synthase by andrographolide in human osteoarthritic chondrocytes

OBJECTIVE

The aim of this study was to investigate the effects of andrographolide on matrix metalloproteinases (MMP) 1, 3, and 13 and inducible nitric oxide synthase (iNOS) in human articular chondrocytes from osteoarthritic cartilage.

METHODS

Passaged chondrocytes were pretreated with or without andrographolide for 2 h, followed by coincubation with interleukin-1 beta (IL-1β) 1 ng/ml for 24 h. Expression levels of MMP-1, 3, and 13, tissue inhibitor of metalloproteinase-1 (TIMP-1), and iNOS were evaluated using real-time-quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting. Nitric oxide (NO) was analyzed using the Griess reaction assay. Involvement of nuclear factor kappa B (NF-κB) was assessed by Western blotting, transient transfection, and luciferase reporter assay.

RESULTS

Andrographolide tested in these in vitro studies was found be an effective antiarthritic agent, as evidenced by potent inhibition of MMP-1, 3, and 13 and iNOS expression, as well as upregulation of TIMP-1 in IL-1β-stimulated human articular chondrocytes (p < 0.05). The mechanism of andrographolide's inhibitory effects was mediated by attenuating the activation of NF-κB in human chondrocytes in the presence of IL-1β.

CONCLUSIONS

Andrographolide was a potent inhibitor of the production of inflammatory and catabolic mediators by chondrocytes, suggesting that this natural compound may merit consideration as a therapeutic agent for treating and preventing osteoarthritis.

Localized controlled release of stratifin reduces implantation-induced dermal fibrosis

Localized controlled release of anti-fibrogenic factors can potentially prevent tissue fibrosis surrounding biomedical prostheses, such as vascular stents and breast implants. We have previously demonstrated that therapeutic intervention with topically applied stratifin in a rabbit ear fibrotic model not only prevents dermal fibrosis but also promotes more normal tissue repair by regulating extracellular matrix deposition. In this work, the anti-fibrogenic effect of a controlled release form of stratifin was investigated in the prevention of fibrosis induced by dermal poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel implants. Pharmacodynamic effects were evaluated by histopathological examination of subcutaneous tissue surrounding implanted composites. Controlled release of stratifin from PLGA microsphere/PVA hydrogel implants significantly moderated dermal fibrosis and inflammation by reducing collagen deposition (30%), total tissue cellularity (48%) and infiltrated CD3(+) immune cells (81%) in the surrounding tissue compared with the stratifin-free implants. The controlled release of stratifin from implants markedly increased the level of matrix metalloproteinase-1 expression in the surrounding tissue, which resulted in less collagen deposition. These stratifin-eluting PLGA/PVA composites show promise as coatings to decrease the typical fibrosis exhibited around implanted biomedical prostheses, such as breast implants and vascular stents.

Characterization of human osteoarthritic cartilage using optical and magnetic resonance imaging

Purpose

Osteoarthritis (OA) is a degenerative disease starting with key molecular events that ultimately lead to the breakdown of the cartilage. The purpose of this study is to use two imaging methods that are sensitive to molecular and macromolecular changes in OA to better characterize the disease process in human osteoarthritic cartilage.

Procedures

Human femoral condyles were collected from patients diagnosed with severe OA during total knee replacement surgeries. T_1ρ and T₂ magnetic resonance measurements were obtained using a 3-Tesla whole body scanner to assess macromolecular changes in the damaged cartilage matrix. Optical imaging was performed on specimens treated with MMPSense 680 to assess the matrix metalloproteinase (MMP) activity. A linear regression model was used to assess the correlation of MMP optical data with T_1ρ magnetic resonance (MR) measurements. Slices from a representative specimen were removed from regions with high and low optical signals for subsequent histological analysis.

Results

All specimens exhibit high T_1ρ and T₂ measurements in the range of 48–75 ms and 36–69 ms, respectively. They also show intense photon signals (0.376 to 7.89 × 10⁻⁴ cm²) from the activated MMPSense 680 probe, indicative of high MMP activity. The analysis of variance test of the regression model indicates a positive correlation between the MMP optical signal and T_1ρ measurements (R² = 0.8936, P = 0.0044). Histological data also confirmed that regions with high MMP optical signal and intense T_1ρ relaxation exhibit severe clefting, abnormal tidemarks, and irregular cellularity.

Conclusions

The high T_1ρ and T₂ measurements suggest that there is a severe loss of proteoglycans with high water mobility in the damaged cartilage. The intense optical signals found in these specimens indicate the presence of active MMPs, and the positive correlation with T_1ρ measurements implicates MMP’s involvement in OA progression, characterized by a severe loss of proteoglycans in the cartilage matrix. The bimodal approach using optical and MR imaging may provide key molecular and macromolecular information of the disease pathway, offering insights toward the development of new tools for the early detection, treatment, and/or prevention of OA.

Classical macrophage activation up-regulates several matrix metalloproteinases through mitogen activated protein kinases and nuclear factor-κB

Remodelling of the extracellular matrix (ECM) and cell surface by matrix metalloproteinases (MMPs) is an important function of monocytes and macrophages. Recent work has emphasised the diverse roles of classically and alternatively activated macrophages but the consequent regulation of MMPs and their inhibitors has not been studied comprehensively. Classical activation of macrophages derived in vitro from un-fractionated CD16^+/− or negatively-selected CD16⁻ macrophages up-regulated MMP-1, -3, -7, -10, -12, -14 and -25 and decreased TIMP-3 steady-state mRNA levels. Bacterial lipopolysaccharide, IL-1 and TNFα were more effective than interferonγ except for the effects on MMP-25, and TIMP-3. By contrast, alternative activation decreased MMP-2, -8 and -19 but increased MMP -11, -12, -25 and TIMP-3 steady-state mRNA levels. Up-regulation of MMPs during classical activation depended on mitogen activated protein kinases, phosphoinositide-3-kinase and inhibitor of κB kinase-2. Effects of interferonγ depended on janus kinase-2. Where investigated, similar effects were seen on protein concentrations and collagenase activity. Moreover, activity of MMP-1 and -10 co-localised with markers of classical activation in human atherosclerotic plaques in vivo. In conclusion, classical macrophage activation selectively up-regulates several MMPs in vitro and in vivo and down-regulates TIMP-3, whereas alternative activation up-regulates a distinct group of MMPs and TIMP-3. The signalling pathways defined here suggest targets for selective modulation of MMP activity.

Anti-inflammatory effects of polyphenolic-enriched red raspberry extract in an antigen-induced arthritis rat model

The red raspberry ( Rubus idaeus ) fruit contains bioactive polyphenols including anthocyanins and ellagitannins with reported anti-inflammatory properties. This study sought to investigate the cartilage-protecting and anti-inflammatory effects of a polyphenolic-enriched red raspberry extract (RRE; standardized to total polyphenol, anthocyanin, and ellagitannin contents) using (1) an in vitro bovine nasal explant cell culture model and (2) an in vivo adjuvant-induced arthritis rat model. RRE contained 20% total polyphenols (as gallic acid equivalents), 5% anthocyanins (as cyanidin-3-glucoside equivalents), and 9.25% ellagitannins (as ellagic acid equivalents). In the in vitro studies, bovine nasal explants were stimulated with 10 ng/mL IL-1β to induce the release of proteoglycan and type II collagen. On treatment with RRE (50 μg/mL), there was a decrease in the rate of degradation of both proteoglycan and type II collagen. In the in vivo antigen-induced arthritis rat model, animals were gavaged daily with RRE (at doses of 30 and 120 mg/kg, respectively) for 30 days after adjuvant injection (750 μg of Mycobacterium tuberculosis suspension in squalene). At the higher dose, animals treated with RRE had a lower incidence and severity of arthritis compared to control animals. Also, histological analyses revealed significant inhibition of inflammation, pannus formation, cartilage damage, and bone resorption by RRE. This study suggests that red raspberry polyphenols may afford cartilage protection and/or modulate the onset and severity of arthritis.

Pravastatin suppresses matrix metalloproteinase expression and activity in human articular chondrocytes stimulated by interleukin-1β

BACKGROUND

Matrix metalloproteinases are catabolic enzymes that play a key role in the articular cartilage degeneration evident in degenerative and inflammatory conditions of articular cartilage. The aim of this study is to assess the ability of pravastatin to modify matrix metalloproteinase (MMP) messenger RNA (mRNA) expression and enzyme activity in a culture of normal human chondrocytes stimulated by interleukin-1β.

MATERIALS AND METHODS

Normal human chondrocytes were stimulated with interleukin (IL)-1β for 6 h to induce MMP expression, simulating a catabolic state, and then treated with pravastatin (1, 5 and 10 μM) for a further 18 h before cell lysates and supernatants were harvested. Cells stimulated with IL-1β but not treated with pravastatin served as controls. Real-time polymerase chain reaction (PCR) was used to assess expression of MMP-3 and MMP-9 mRNA. MMP enzyme activity was assessed using a fluorescent MMP-specific substrate. Statistical analysis was performed using analysis of variance (ANOVA).

RESULTS

MMP-3 and MMP-9 mRNA expression was reduced at all concentrations tested with statistically significant trends in reduction (p = 0.002 and <0.001, respectively). Analysis of culture supernatants revealed that pravastatin treatment led to a reduction in total MMP activity but not to a statistically significant degree (p = 0.07).

CONCLUSIONS

Treatment with pravastatin of stimulated human chondrocytes leads to significant down-regulation of selected MMP genes and a non-significant reduction in MMP enzyme activity. Our results provide further evidence that statins may have a role to play in future treatment of disease affecting articular chondrocytes.

Activation of COL1A2 promoter in human fibroblasts by Escherichia coli

The relationship between bacterial infection and collagen production was investigated using human fibroblasts transfected with the promoter of COL1A2 , which encodes the α1 chain of human type I collagen, linked to a luciferase reporter. The cells were used to assess the gene promoter activity of COL1A2 following bacterial stimulation. The COL1A2 promoter was activated by stimulation with fixed Escherichia coli in a dose-dependent manner, but not by fixed Staphylococcus aureus. Enhancement of collagen production was observed in the E. coli-stimulated fibroblasts compared to those without stimulation. Both anti-human Toll-like receptor (TLR) 4 antibody and polymyxin B clearly blocked the COL1A2 promoter activity stimulated by E. coli, while antibodies against human TLR2 and human transforming growth factor-β (TGF-β) receptor type II did not. These results indicate that E. coli can directly interact with TLR4 expressed on the surface of fibroblasts and can further induce human type I collagen gene expression and collagen production in these cells. These data also suggest that infection by gram-negative bacteria may cause fibrosis.

A cell-matrix model of anabolic and catabolic dynamics during cartilage biomolecule regulation

Physiologic regulation of extracellular matrix (ECM) in articular cartilage tissue is controlled by cellular and molecular mechanisms which are not fully understood. It has been observed that the synthesis of the ECM structural molecules, glycosaminoglycan and collagen are promoted by growth factors such as IGF-1 and TGF-β. Concomitant ECM degradation is promoted by a variety of cytokines such as IL-1. The clinical need for reparative therapies of articular cartilage is linked with its poor intrinsic healing capacity. The following modelling approach was applied to engineered cartilage as a platform for exploring cartilage biology and to introduce a predictive tool as a bioinformatic support system supporting regenerative therapies. Systems biology was adapted through a mathematical framework producing a computational intelligence paradigm to explore a controlled phasic regulatory influence of the inhibition and production of ECM biomolecules. Model outcomes describe a steady synthesis of ECM as a dependence on a cyclic influence of the catabolic action of proteases and anabolic action of growth factors. This relationship is shown quantitatively in a governing harmonic equation representing the simplified biological mechanisms of biomolecule homeostasis.

Implication of MMP-9 and urokinase plasminogen activator (uPA) in the activation of pro-matrix metalloproteinase (MMP)-13

We examined whether the expression and activation of pro-matrix metalloproteinase (MMP)-1 varies from that of pro-MMP-13 in the joint fluid of osteoarthritis (OA) and rheumatoid arthritis (RA) patients. To do this, joint fluid was collected from 34 RA and 34 OA patients. The collagenase (pro-MMP-1 and MMP-13, total MMP-1, and MMP-13), gelatinase (total MMP-2 and MMP-9), stromelysin (total MMP-3), matrilysin (total MMP-7), uPA, and tissue inhibitor of MMP (TIMP) levels were measured by ELISA. The level of total MMP-1 in RA joint fluids was similar to that of the OA joint fluid. In contrast, the level of total MMP-13 in the RA group was significantly higher than that of the OA group. Among various MMPs (MMP-2, MMP-3, MMP-7, and MMP-9), only MMP-9 was strongly associated with total MMP-13 in both RA and OA. The level of uPA was also strongly associated with MMP-13 in RA but not OA, while the level of TIMP-1 and TIMP-2 was not significantly different between RA and OA. In conclusion, MMP-9 and uPA might be involved in the activation of pro-MMP-13 through unknown mechanisms in arthritic diseases.

Coupling plowing of cartilage explants with gene expression in models for synovial joints

Articular cartilage undergoes complex loading modalities generally including sliding, rolling and plowing (i.e. the compression by a condyle normally to the tissue surface under simultaneously tangential displacement, thus generating a tractional force due to tissue deformation). Although in in vivo studies it was shown that excessive plowing can lead to osteoarthritis, little quantitative experimental work on this loading modality and its mechanobiological effects is available in the literature. Therefore, a rolling/plowing explant test system has been developed to study the effect on pristine cartilage of plowing at different perpendicular forces. Cartilage strips harvested from bovine nasal septa of 12-months-old calves were subjected for 2h to a plowing-regime with indenter normal force of 50 or 100 N and a sliding speed of 10 mm s(-1). 50 N produced a tractional force of 1.2±0.3N, whereas 100 N generated a tractional force of 8.0±1.4N. Furthermore, quantitative-real-time polymerase chain reaction experiments showed that TIMP-1 was 2.5x up-regulated after 50 N plowing and 2x after 100 N plowing, indicating an ongoing remodeling process. The expression of collagen type-I was not affected after 50 N plowing but it was up-regulated (6.6x) after 100 N plowing, suggesting a possible progression to an injury stage of the cartilage, as previously reported in cartilage of osteoarthritic patients. We conclude that plowing as performed by our mimetic system at the chosen experimental parameters induces changes in gene expression depending on the tractional force, which, in turn, relates to the applied normal force.

Synthesis, in vitro evaluation, and in vivo metabolism of fluor/quencher compounds containing IRDye 800CW and Black Hole Quencher-3 (BHQ-3)

Protease-cleavable peptides containing a suitable fluor/quencher (Fl/Q) pair are optically dark until cleaved by their target protease, generating fluorescence. This approach has been used with many Fl/Q pairs, but little has been reported with IRDye 800CW, a popular near-infrared (NIR) fluor. We explored the use of the azo-bond-containing Black Hole Quencher 3 (BHQ-3) as a quencher for IRDye 800CW and found that IRDye 800CW/BHQ-3 is a suitable Fl/Q pair, despite the lack of proper spectral overlap for fluorescence resonance energy transfer (FRET) applications. Cleavage of IRDye 800CW-PLGLK(BHQ-3)AR-NH(2) (8) and its D-arginine (Darg) analogue (9) by matrix metalloproteinases (MMPs) in vitro yielded the expected cleavage fragments. In vivo, extensive metabolism was found. Significant decomposition of a "non-cleavable" control IRDye 800CW-(1,13-diamino-4,7,10-trioxatridecane)-BHQ-3 (10) was evident in plasma of normal mice by 3 min post injection. The major metabolite showed a m/z and UV/vis spectrum consistent with azo bond cleavage in the BHQ-3 moiety. Preparation of an authentic standard of this metabolite (11) confirmed the assignment. Although the IRDye 800CW/BHQ-3 constructs showed efficient contact quenching prior to enzymatic cleavage, BHQ-3 should be used with caution in vivo, due to instability of its azo bond.

Mycobacterium tuberculosis-infected human monocytes down-regulate microglial MMP-2 secretion in CNS tuberculosis via TNFα, NFκB, p38 and caspase 8 dependent pathways

Tuberculosis (TB) of the central nervous system (CNS) is a deadly disease characterized by extensive tissue destruction, driven by molecules such as Matrix Metalloproteinase-2 (MMP-2) which targets CNS-specific substrates. In a simplified cellular model of CNS TB, we demonstrated that conditioned medium from Mycobacterium tuberculosis-infected primary human monocytes (CoMTb), but not direct infection, unexpectedly down-regulates constitutive microglial MMP-2 gene expression and secretion by 72.8% at 24 hours, sustained up to 96 hours (P < 0.01), dependent upon TNF-α. In human CNS TB brain biopsies but not controls the p38 pathway was activated in microglia/macrophages. Inhibition of the p38 MAP kinase pathway resulted in a 228% increase in MMP-2 secretion (P < 0.01). In contrast ERK MAP kinase inhibition further decreased MMP-2 secretion by 76.6% (P < 0.05). Inhibition of the NFκB pathway resulted in 301% higher MMP-2 secretion than CoMTb alone (P < 0.01). Caspase 8 restored MMP-2 secretion to basal levels. However, this caspase-dependent regulation of MMP-2 was independent of p38 and NFκB pathways; p38 phosphorylation was increased and p50/p65 NFκB nuclear trafficking unaffected by caspase 8 inhibition. In summary, suppression of microglial MMP-2 secretion by M.tb-infected monocyte-dependent networks paradoxically involves the pro-inflammatory mediators TNF-α, p38 MAP kinase and NFκB in addition to a novel caspase 8-dependent pathway.

Matrix metalloproteinases and inhibitors in cartilage tissue engineering

Inhibiting matrix metalloproteinase (MMP) activity has been considered as a potential therapeutic treatment that may modify the outcome for osteoarthritis (OA), a disease governed by abnormalities in the balance between MMPs and their inhibitors. Due to unexpected tissue fibrosis in early-phase clinical trials with some MMP inhibitors, possible divergent effects of inhibiting MMP activity on different cells are hypothesized. Therefore, we evaluated the effects of MMP inhibition on cells relevant to cartilage tissue engineering by culturing them in vitro in poly(ethylene glycol) diacrylate hydrogels to create 3D representations of cartilage tissue while allowing for local and direct administration of inhibitors. Mesenchymal stem cells demonstrated an inhibitor concentration-dependent decrease in extracellular matrix (ECM) deposition, while normal chondrocytes were mainly affected at the highest concentration of inhibitors. In contrast, the concomitant treatment of chondrocytes from patients with OA resulted in an increase in glycosaminoglycan content only in the presence of both inhibitors and anabolic growth factors. The observed upregulation of bone markers, however, indicates a delicate balance that must be addressed to therapeutically treat OA chondrocytes to stimulate more ECM production without errant bone formation. In conclusion, this study suggests that MMPs have complex interactions in both pathobiology and homeostasis.

Effects of T-2 toxin and selenium on chondrocyte expression of matrix metalloproteinases (MMP-1, MMP-13), α2-macroglobulin (α2M) and TIMPs

T-2 toxin is regarded as an important etiological factor of Kashin-Beck disease, and supplementation of selenium-salt partly prevents Kashin-Beck disease. The present study investigated the effects of T-2 toxin on the degradation of type II collagen in human chondrocytes in vitro. Human chondrocytes were isolated and cultured on bone matrix gelatin to form an artificial cartilage model in vitro with or without T-2 toxin and selenium. Immunohistochemistry analyses showed that T-2 toxin decreased type II collagen staining and selenium appeared to prevent the decrease in type II collagen induced by T-2 toxin in engineered cartilage. Then, Western blot and RT-PCR analyses showed that an increase in MMP-13 and MMP-1 expressions, and a decrease in the expression of the general endoproteinase inhibitor (α(2)M) were induced by T-2 toxin. Gelatin reverse zymography showed that TIMP-1 and TIMP-2 levels were decreased in a dose-dependent manner after exposure of T-2 toxin. Selenium had a protective role by increasing the level of type II collagen protein through down-regulation of MMP-13 protein and mRNA expression and up-regulation of TIMP-1 and TIMP-2 expressions. These data suggest T-2 toxin induces cartilage matrix degradation by the up-regulation of MMP-13 and TIMP-1, and down-regulation of TIMP-2 and α(2)M expressions.

Thymoquinone inhibits matrix metalloproteinase expression in rabbit chondrocytes and cartilage in experimental osteoarthritis

Thymoquinone (TQ) is the main constituent of Nigella sativa oil, which has been traditionally used against arthritis in the Middle East. In this study, we investigated the effect of TQ against matrix metalloproteinase (MMP) expression in both rabbit chondrocytes and animal mode of osteoarthritis (OA) induced by anterior cruciate ligament transection and tested whether or not nuclear factor kappa B (NF- κB) was involved in this process. TQ down-regulated MMP-1, MMP-3 and MMP-13 expression and up-regulated tissue inhibitors of metalloproteinase-1 expression as assessed by quantitative realtime polymerase chain reaction. In addition, NF- κB p65 protein level as well as its translocation induced by interleukin-1 β were inhibited by TQ. Our findings suggest the potential of TQ in the treatment of OA.

Interaction of periosteal explants with articular chondrocytes alters expression profile of matrix metalloproteinases

Periosteal tissue is a source of growth factors and of osteochondral progenitor cells which makes it suitable for implantation in chondral defects as known in autologous chondrocyte implantation. The aim of this study was to determine the interaction between periosteal tissue and articular chondrocytes with respect to catabolic effectors such as matrix metalloproteinases (MMPs) and IL-6. Human articular chondrocytes were cultured for up to 28 days as micromass pellets in coculture either with physical contact to periosteal explants or allowing paracrine interactions only. Expression, secretion, and activation of MMPs and IL-6 were analyzed in chondrocytes, periosteum, and culture supernatants. Both coculture conditions influence gene expression levels of MMPs and IL-6 in a time-, culture-, and tissue-dependent manner. Coculturing of periosteum with chondrocytes promotes gene expression and secretion of IL-6. In periosteum, physical contact inhibits MMP-2 and MMP-13 gene expression while paracrine coculture induces expression of IL-6, MMP-2, -7, and -13. Pro-MMP-2, -7, and -13 were detected in supernatants of all culture regimens whereas pro-MMP-9 was secreted from periosteum only. As a balanced amount of MMP activity is likely required to achieve sufficient integration of the regenerate tissue with the surrounding healthy cartilage, an exceeding expression of proteinases might result in degradation, hypertrophy or rejection of the graft.

Effect of taurine chloramine on the production of matrix metalloproteinases (MMPs) in adiponectin- or IL-1beta-stimulated fibroblast-like synoviocytes

BACKGROUND

Adiponectin greatly stimulated the expression of matrix metalloproteinases (MMPs) in fibroblast-like synoviocytes (FLSs) as did IL-1beta. We wondered whether taurine chloramine (TauCl) inhibits the production of MMPs stimulated by adiponectin in the same pattern as by IL-1beta stimulation in vitro

METHODS

Synovial cells from rheumatoid arthritis (RA) patients were treated with adiponectin or interleukin (IL)-1beta for 24 hr in the presence or absence of TauCl. The culture supernatant was collected and the levels of MMPs were measured by enzyme-linked immunosorbent assay (ELISA). The IkappaB signaling pathways stimulated by adiponectin were studied and the levels of NF-kappaB in the nuclei of the cells were analyzed by ELISA.

RESULTS

TauCl (600 microM) inhibited MMP-13, but not MMP-1, expression in IL-1beta-stimulated RA FLSs. However, TauCl at the same concentration significantly inhibited the production of both adiponectin-stimulated MMP-1 and MMP-13 expression. TauCl inhibited the degradation of IkappaB-alpha stimulated by adiponectin, but not by IL-1beta. Similarly, the level of NF-kappaB in the nucleus was increased by adiponectin stimulation and was inhibited by 600 microM TauCl. However, the levels of NF-kappaB increased by IL-1beta stimulation were not inhibited by 600 microM TauCl.

CONCLUSIONS

TauCl more effectively inhibited MMPs expression induced by adiponectin than that by IL-1beta in RA FLS, suggesting that TauCl plays an important role in down-regulating the expression of MMPs in arthritic joints.

The presence of extracellular matrix degrading metalloproteinases during fetal development of the intervertebral disc

Matrix metalloproteinases (MMPs) regulate connective tissue architecture and cell migration through extracellular matrix (ECM) degradation and are associated with both physiological and pathological processes. Although they are known to play a role in skeletal development, little is known about the role of MMPs in intervertebral disc (IVD) development. Sixteen fetal human lumbar spine segments, obtained at autopsy, were compared with five normal, non-fetal L4–L5 IVDs. Intensity and/or localization of immunohistochemical staining for MMP-1, -2, -3 and -14 were evaluated by three independent observers. MMP-2 production and activation was quantified by gelatin zymography. MMP-1 and -14 were abundantly present in the nucleus pulposus (NP) and notochordal (NC) cells of the fetal IVDs. In non-fetal IVDs, MMP-1 and -14 staining was significantly less intense (p = 0.001 and p < 0.001, respectively). MMP-3 was found in almost the entire IVD with no significant difference from non-fetal IVDs. MMP-2 staining in the NC and NP cells of the fetal IVD was moderate, but weak in the non-fetal IVD. Gelatin zymography showed a negative correlation of age with MMP-2 activity (p < 0.001). MMP-14 immunostaining correlated positively with MMP-2 activity (p = 0.001). For the first time, the presence of MMP-1, -2, -3 and -14 in the fetal human IVD is shown and the high levels of MMP-1, -2 and -14 suggest a role in the development of the IVD. In particular, the gradual decrease in MMP-2 activation during gestation pinpoints this enzyme as key player in fetal development, possibly through activation by MMP-1 and -14.

Hylan G-F 20 has better pain relief and cost-effectiveness than sodium hyaluronate in treating early osteoarthritic knees in Taiwan

BACKGROUND/PURPOSE

Intra-articular injection of hyaluronan (hyaluronic acid; HA) products is available to treat early osteoarthritis (OA) of the knee in Taiwan. We tested whether HA products with different molecular weights have significantly different effects on clinical efficacy and cost-effectiveness.

METHODS

Thirty-seven patients with mild to moderate OA of both knees underwent five weekly intra-articular injections of sodium hyaluronate (Artz) in one knee and three weekly intra-articular injections of chemically cross-linked Hylan G-F 20 (Synvisc) in the other. Visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne's index, and Hospital for Special Surgery (HSS) knee scores were compared initially and at the last injection, and at 8, 12, 16, 20, and 26 weeks after the first injection.

RESULTS

VAS, WOMAC, WOMAC-A1 (pain when walking on a flat surface) scores before week 16, HSS scores before week 12, and Lequesne's index scores except at week 26 all showed that HA significantly improved the scores time-dependently. In VAS scores, Synvisc showed better improvement before week 20, while this effect appeared at week 12 for the WOMAC-A1 scores. The incremental cost-effectiveness ratio of the Taiwan National Health Insurance Program, of the patient, and both of these was lower for Synvisc, which also reduced the number of additional hospital visits for injections by two.

CONCLUSION

Synvisc possesses better symptom-modifying ability and cost-utility in treating early OA of the knee in Taiwan.

TIP39/parathyroid hormone type 2 receptor signaling is a potent inhibitor of chondrocyte proliferation and differentiation

Tuberoinfundibular peptide of 39 residues (TIP39) is a member of the parathyroid hormone (PTH) family of peptide hormones that exerts its function by interacting with the PTH type 2 receptor (PTH2R). Presently, no known function has been attributed to this signaling pathway in the developing skeleton. We observed that TIP39 and PTH2R were present in the newborn mouse growth plate, with the receptor localizing in the resting zone whereas ligand expression was restricted exclusively in prehypertrophic and hypertrophic chondrocytes. By 8 wk of life, PTH2R, and to a lesser degree TIP39, immunoreactivity was present in articular chondrocytes. We therefore sought to investigate the role of TIP39/PTH2R signaling in chondrocytes by generating stably transfected CFK2 chondrocytic cells overexpressing PTH2R (CFK2R). TIP39 treatment of CFK2R clones in culture inhibited their proliferation by restricting cells at the G(0)/G(1) phase of the cell cycle, coupled with decreased expression and activity of cyclin-dependent kinases Cdk2 and Cdk4, while p21, an inhibitor of Cdks, was upregulated. In addition, TIP39 treatment decreased expression of differentiation markers in these cells associated with marked alterations in extracellular matrix and metalloproteinase expression. Transcription of Sox9, the master regulator of cartilage differentiation, was reduced in TIP39-treated CFK2R clones. Moreover, Sox9 promoter activity, as measured by luciferase reporter assay, was markedly diminished after TIP39 treatment. In summary, our results show that TIP39/PTH2R signaling inhibits proliferation and alters differentiation of chondrocytes by modulating SOX9 expression, thereby substantiating the functional significance of this signaling pathway in chondrocyte biology.

Characterization of Fibrodysplasia in the Dog Following Inhibition of Metalloproteinases

Musculoskeletal side effects are a widely reported consequence of administration of particular matrix metalloproteinase inhibitors (MMPi) in clinical trials. We describe here histopathological findings during dog studies with a fairly selective MMPi AZM551248, that are consistent with these human clinical changes. They were characterized by a dose-and time-dependent formative connective tissue alteration we have termed “fibrodysplasia.” The most sensitive site was the subcuticular connective tissue, although musculoskeletal tissues were also extensively involved. In the subcutis, changes occurred initially around pre-existing blood vessels, but then more diffusely. There was proliferation of cells showing myofibroblast differentiation identified by elevated levels of alpha-smooth muscle actin, fibronectin, and transforming growth factor β, and the deposition of collagen type III with a lesser quantity of collagen type I. On longer-term administration at lower doses, there was evidence of active fibrodysplasia arising and resolving during the dosing period, resulting in the multifocal deposition of mature collagen. Although there was organ specificity, essentially identical changes occurred at multiple connective tissue sites. We conclude that MMPi-induced fibrodysplasia in animals and, by inference, musculoskeletal side effects in humans are potentially diffuse connective tissue disorders.

Beta1 integrin deficiency results in multiple abnormalities of the knee joint

The lack of beta1 integrins on chondrocytes leads to severe chondrodysplasia associated with high mortality rate around birth. To assess the impact of beta1 integrin-mediated cell-matrix interactions on the function of adult knee joints, we conditionally deleted the beta1 integrin gene in early limb mesenchyme using the Prx1-cre transgene. Mutant mice developed short limbed dwarfism and had joint defects due to beta1 integrin deficiency in articular regions. The articular cartilage (AC) was structurally disorganized, accompanied by accelerated terminal differentiation, altered shape, and disrupted actin cytoskeleton of the chondrocytes. Defects in chondrocyte proliferation, cytokinesis, and survival resulted in hypocellularity. However, no significant differences in cartilage erosion, in the expression of matrix-degrading proteases, or in the exposure of aggrecan and collagen II cleavage neoepitopes were observed between control and mutant AC. We found no evidence for disturbed activation of MAPKs (ERK1/2, p38, and JNK) in vivo. Furthermore, fibronectin fragment-stimulated ERK activation and MMP-13 expression were indistinguishable in control and mutant femoral head explants. The mutant synovium was hyperplastic and frequently underwent chondrogenic differentiation. beta1-null synoviocytes showed increased proliferation and phospho-focal adhesion kinase expression. Taken together, deletion of beta1 integrins in the limb bud results in multiple abnormalities of the knee joints; however, it does not accelerate AC destruction, perturb cartilage metabolism, or influence intracellular MAPK signaling pathways.