Transcriptional regulation of collagenase (MMP-1, MMP-13) genes in arthritis: integration of complex signaling pathways for the recruitment of gene-specific transcription factors

LIGHT up-regulated on B lymphocytes and monocytes in rheumatoid arthritis mediates cellular adhesion and metalloproteinase production by synoviocytes

OBJECTIVE

To study the expression of LIGHT (tumor necrosis factor superfamily 14) and herpesvirus entry mediator (HVEM; tumor necrosis factor receptor superfamily 14) in rheumatoid arthritis (RA) and to determine the regulatory role of LIGHT on the effector functions of fibroblast-like synoviocytes (FLS).

METHODS

The expression of LIGHT and HVEM was assessed by immunohistochemical staining of synovial tissue and by flow cytometric analysis of mononuclear cells. The presence of HVEM and lymphotoxin beta receptor was measured by reverse transcriptase-polymerase chain reaction and by flow cytometry. The regulation of effector molecules, including matrix metalloproteinases (MMPs) and adhesion molecules, was evaluated. The adhesiveness of FLS was determined by adhesion assay.

RESULTS

HVEM was detected in most cell types within rheumatoid synovial tissue, while only a few cells were positive for LIGHT. In RA patients, LIGHT expression was significantly up-regulated only in CD20+ B cells and monocytes, whereas the mean fluorescence intensity of HVEM was down-regulated in mononuclear cells. The stimulation of FLS with LIGHT resulted in the production of MMPs and the expression of adhesion molecules, which were efficiently inhibited by dexamethasone. LIGHT-mediated up-regulation of MMPs and intercellular adhesion molecule 1 was blocked by inhibitors of NF-kappaB and JNK, whereas up-regulation of vascular cell adhesion molecule 1 was blocked by inhibitors of phosphatidylinositol 3-kinase, as well as NF-kappaB.

CONCLUSION

These data suggest that binding of LIGHT with its receptors may play a role in the progression of inflammation within rheumatoid synovium, especially by mediating the interactions between infiltrating inflammatory cells and stromal cells. These findings thus emphasize the relevance of LIGHT as a potential therapeutic target in RA.

Helicobacter pylori stimulates gastric epithelial cell MMP-1 secretion via CagA-dependent and -independent ERK activation

Because the mechanisms of Helicobacter pylori-induced gastric injury are incompletely understood, we examined the hypothesis that H. pylori induces matrix metalloproteinase-1 (MMP-1) secretion, with potential to disrupt gastric stroma. We further tested the role of CagA, an H. pylori virulence factor, in MMP-1 secretion. Co-incubation of AGS cells with Tx30a, an H. pylori strain lacking the cagA virulence gene, stimulated MMP-1 secretion, confirming cagA-independent secretion. Co-incubation with strain 147C (cagA(+)) resulted in CagA translocation into AGS cells and increased MMP-1 secretion relative to Tx30a. Transfection of cells with the recombinant 147C cagA gene also induced MMP-1 secretion, indicating that CagA can independently stimulate MMP-1 secretion. Co-incubation with strain 147A, containing a cagA gene that lacks an EPIYA tyrosine phosphorylation motif, as well as transfection with 147A cagA, yielded an MMP-1 secretion intermediate between no treatment and 147C, indicating that CagA tyrosine phosphorylation regulates cellular signaling in this model system. H. pylori induced activation of the MAP kinase ERK, with CagA-independent (early) and dependent (later) components. MEK inhibitors UO126 and PD98059 inhibited both CagA-independent and -dependent MMP-1 secretion, whereas p38 inhibition enhanced MMP-1 secretion and ERK activation, suggesting p38 negative regulation of MMP-1 and ERK. These data indicate H. pylori effects on host epithelial MMP-1 expression via ERK, with p38 playing a potential regulatory role.

Impact of Pycnogenol® on cardiac extracellular matrix remodeling induced by l-NAME administration to old mice

Cardiac remodeling is a determinant of the clinical progression of heart failure and now slowing or reversing remodeling is considered as a potential therapeutic target in heart failure. Pycnogenol has been reported to mediate a number of beneficial effects in the cardiovascular system but its effects on hemodynamic and functional cardiovascular changes following cardiac remodeling have not been elucidated. Therefore, we investigated the influence of Pycnogenol supplementation (30 mg/kg) on left ventricular function and myocardial extracellular matrix composition in old C57BL/6N mice following induction of cardiac remodeling by chronic nitric oxide synthase blockade by NG-nitro-L-arginine methyl ester (L-NAME) administration. L-NAME-treated mice demonstrated dilated cardiomyopathy at compensated state, associated with a significant increase of pro-matrix metalloproteinase (MMP)-9 gene expression and activity, a marked decrease in pro-collagen IIIalpha1 gene expression, and a subsequent reduction in cardiac total and cross-linked collagen content. Upon supplementation with Pycnogenol in L-NAME-exposed mice, cardiac gene expression patterns for pro-MMP-2, -9, and -13, and MMP-9 activity were significantly decreased, associated with a significant increase in cardiac tissue inhibitor of metalloproteinase (TIMP)-4 expression. These findings were coincided with a marked increase in myocardial total and cross-linked collagen content, compared with L-NAME-only-treated mice. Moreover, Pycnogenol treatment was associated with reversal of L-NAME-induced alternations in hemodynamic parameters. These data indicate that Pycnogenol can prevent adverse myocardial remodeling induced by L-NAME, through modulating TIMP and MMPs gene expression, MMPs activity, and further reduction in myocardial collagen degradation rate.

The chemopreventive polyphenol Curcumin prevents hematogenous breast cancer metastases in immunodeficient mice

Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitroand in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA-MB-231 cells in correlation with reduced activation of the survival pathway NFkappaB, as a consequence of diminished IotakappaB and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NFkappa B activity and transcriptional downregulation of AP-1. NFkappa B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NFkappa B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NFkappa B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible.

RelA is required for IL-1beta stimulation of Matrix Metalloproteinase-1 expression in chondrocytes

OBJECTIVE

Interleukin-1beta (IL-1beta) stimulates collagenase-1 (Matrix Metalloproteinase-1 (MMP-1)) expression in articular chondrocytes, leading to cleavage of type II collagen and irreversible cartilage degradation. The nuclear factor-kappa B (NF-kappaB) pathway is potently activated in IL-1beta-stimulated cells and has been implicated as an intermediate in MMP-1 gene expression. However, the roles of individual NF-kappaB family members during IL-1beta-induced MMP-1 gene expression have not been defined.

RESULTS

To address the relationship between the NF-kappaB pathway and MMP-1 gene activation in chondrocytes, primary cultured human articular chondrocyte cultures (HAC) and SW-1353 cells were stimulated with IL-1beta over a 24-h time course and MMP-1, NF-kappaB1, NF-kappaB2 and RelA gene expression was assayed. IL-1beta-induced MMP-1 expression was comparable in HAC and SW-1353 cells both temporally and quantitatively. MMP-1 gene expression was mirrored by increases in NF-kappaB gene expression, and inhibition of NF-kappaB nuclear translocation with dominant-negative IkappaBalpha reduced IL-1beta-dependent MMP-1 gene expression. IL-1beta activated the NF-kappaB pathway in chondrocytes, both through phosphorylation and transient degradation of IkappaBalpha, as well as through sustained phosphorylation of RelA. Small inhibitory RNAs (siRNA) specific for RelA resulted in significant reduction of MMP-1 mRNA, whereas siRNA for NF-kappaB1 and NF-kappaB2 augmented IL-1beta-induced MMP-1 expression.

CONCLUSIONS

Our data demonstrate that IL-1beta activation of the NF-kappaB pathway is required for IL-1beta induction of MMP-1 in chondrocytes and that RelA can work independently of NF-kappaB1 or NF-kappaB2 to activate this gene expression program.

Regulation of matrix metalloproteinase gene expression

The metalloproteinases degrade extracellular matrix (ECM) components and activate growth factors, thereby contributing to physiological events (tissue remodeling in pregnancy, wound healing, angiogenesis) and pathological conditions (cancer, arthritis, periodontitis). The intent of this review is to bring together various studies on transcriptional and post-transcriptional control of metalloproteinase expression. Certainly, much information is known as to the cis-elements and corresponding trans-activators regulating expression of these genes. We discuss the fact that a number of the metalloproteinase promoters share common structural features and, therefore, not surprisingly are co-regulated in their expression to some extent. More recently, much effort has been devoted to understanding the role of chromatin in regulating gene expression. While this area has been understudied with respect to matrix metalloproteinase (MMP) regulation, the literature indicates a convincing role for both histone modifications and chromatin-remodeling motors in controlling expression of multiple metalloproteinases. In addition to transcriptional control, mRNA stability and protein translation also contribute to the metalloproteinase product amount. We discuss such studies and how various biological cues, including TGF-beta, regulate the levels of certain collagenases either solely through mRNA stabilization or by jointly targeting transcriptional and post-transcriptional mechanisms. We also discuss the current deficits in our knowledge, concerning tissue-specific expression and why despite elevated amounts/activity of trans-activators targeting MMP promoters in tumor cells, nevertheless, MMP expression is largely restricted to the stromal compartment. Finally, we argue for potential technologies to regulate MMP expression of utility in pathological conditions where these enzymes are aberrantly expressed.

Roxithromycin inhibits tumor necrosis factor-alpha-induced matrix metalloproteinase-1 expression through regulating mitogen-activated protein kinase phosphorylation and Ets-1 expression

BACKGROUND AND OBJECTIVE

In periodontitis, matrix metalloproteinases (MMPs) are upregulated in response to locally released inflammatory cytokines, resulting in pathologic processes. Roxithromycin is a 14-membered ring macrolide antibiotic with broad-spectrum antibacterial effects against oral pathogens and immunomodulatory effects. Recently, we reported that roxithromycin inhibits tumor necrosis factor (TNF)-alpha-induced vascular endothelial growth factor expression in human periodontal ligament (HPDL) cell cultures. In the present study, we examined the effect of roxithromycin on TNF-alpha-induced MMP-1 production by HPDL cells.

MATERIAL AND METHODS

Cultured cells were incubated with 1% fetal bovine serum for 24 h, followed by treatment with 10 ng/ml TNF-alpha, 10 microM roxithromycin, and mitogen-activated protein kinase inhibitor at various concentrations. Culture supernatants and sediments were collected at different time-points and used for enzyme-linked immunosorbent assays, and northern and western blot analyses.

RESULTS

In HPDL cell cultures, roxithromycin strongly inhibited TNF-alpha-induced MMP-1 mRNA expression and production. The inhibition of MMP-1 gene expression by roxithromycin was dependent on de novo protein synthesis and was regulated at the transcriptional level. Roxithromycin significantly inhibited TNF-alpha-induced c-Jun N-terminal kinase activation (JNP) and marginally inhibited extracellular signal-regulated kinase (ERK) 1/2 activation, but not p38 mitogen-activated protein kinase activation. Furthermore, roxithromycin reduced the induction of Ets-1, one of the critical factors in MMP-1 transcription.

CONCLUSION

Roxithromycin inhibits TNF-alpha-mediated MMP-1 induction through the downregulation of ERK1/2 and JNK activation and the subsequent reduction of Ets-1, suggesting that roxithromycin may have therapeutic use in periodontitis and other chronic inflammatory conditions involving MMP-1 induction.

Haplotype Effects on Matrix Metalloproteinase-1 Gene Promoter Activity in Cancer Cells

Increased expression of matrix metalloproteinase-1 (MMP1) is associated with poor prognosis in cancers. Several single nucleotide polymorphisms (-1607GG>G, -839G>A, -755G>T, -519A>G, -422T>A, -340C>T, and 320C>T) in the MMP1 gene promoter have recently been identified. In this study, we assessed the functional effects of these polymorphisms on MMP1 gene promoter activity in cell lines of melanoma (A2058 and A375), breast cancer (MCF7 and MDA-MB-231), lung cancer (A549 and H69), and colorectal cancer (HT-29, SW-620) by comparing the promoter strengths of 10 most common haplotypes deriving from these polymorphisms. In A2058 cells, the GG-G-G-A-T-T-T and GG-G-G-A-C-T haplotypes had 2-fold higher promoter activity than the GG-G-T-A-T-T-C, GG-G-G-A-A-T-T, GG-G-G-A-T-T-C, and GG-G-G-A-A-C-T haplotypes, which in turn, had 3-fold higher promoter activity than the G-G-T-A-A-C-T, G-A-T-G-T-T-T, G-A-T-G-A-C-T, and G-A-T-G-A-T-G haplotypes. In A375 and MDA-MB-231 cells, high expression haplotypes include not only the -1607GG-bearing haplotypes but also the G-A-T-G-A-T-T haplotype containing the -1607G allele. A similar trend was detected in A549 cells. In addition, in A549 cells, the GG-G-G-A-T-T-T haplotype had >2-fold higher promoter activity than several other -1607GG-bearing haplotypes. In MCF7 cells, the GG-G-G-A-T-T-T and G-G-T-A-A-C-T haplotypes had 1.5- to 4-fold higher promoter activity than the other haplotypes. These results suggest that the polymorphisms exert haplotype effects on the transcriptional regulation of the MMP1 gene in cancer cells, and indicate a need to examine haplotypes rather than any single polymorphism in genetic epidemiologic studies of the MMP1 gene in cancers.

Native and fragmented fibronectin oppositely modulate monocyte secretion of MMP-9

Monocytes remodel the extracellular matrix (ECM) by secreting proteins composing the ECM such as fibronectin (FN) and degrading proteases such as matrix metalloproteinase-9 (MMP-9), which cleaves FN into fragments. The effects of FN and its fragmented products on the expression of monocyte MMP-9 are controversial and largely unknown. We showed that in human monocytes, the proinflammatory cytokine TNF-alpha induced MMP-9 secretion and increased fragmentation of FN into distinct fragments. When primary monocytes or the U937 monocytic cell line were incubated on a plastic substrate, plastic-coated with native FN, and plastic-coated with fragmented FN (frag-FN), native FN inhibited TNF-alpha-induced proMMP-9 secretion by twofold (P<0.01) compared with plastic or frag-FN. Exploration of the dynamics of inflammation by incubating cells sequentially on the three substrates showed that frag-FN opposed the inhibitory effect of native FN. Inhibition of proMMP-9 by native FN was exerted at the translational level, as no change in MMP-9 mRNA, intracellular protein accumulation, or proteomic degradation was observed, and when degradation was blocked, no de novo translation of MMP-9 could be measured. We also showed that the reduction of MMP-9 secretion by native FN was responsible for attenuated migration of U937 cells (P<0.05). We suggest that in the inflammatory tissue, intact, native FN has a homeostatic role in harnessing MMP-9 activity. However, as fragmented products accumulate locally, they alleviate the inhibition and enable faster migration of the monocytes through the degraded ECM.

An evaluation of anti-TNF-alpha-therapy in patients with ankylosing spondylitis: imbalanced activation of NF kappa B subunits in lymphocytes and modulation of serum cortisol concentration

The aim of this study was to analyse patients with ankylosing spondylitis (AS) during the course of infliximab therapy. The molecular effects were evaluated using lymphocytes and sera that were isolated before therapy began, then again after 2 and 12 weeks from 17 AS patients and compared to those of 24 healthy control individuals. All 17 AS patients responded to treatment with infliximab as assessed using BASDAI. Elevated serum levels of IL-6, CRP and cortisol were reduced to normal levels by the 12 weeks time point. The level of DNA-binding p65 was decreased during the course of infliximab therapy whereas the level of DNA-binding p50 remained elevated until the 12 weeks time point. Taken together, Infliximab is an effective treatment for AS and results in decreased levels of the inflammation markers IL-6 and CRP, and of endogenous cortisol concentration. Unequal alterations in the levels of activated NF-kappaB subunits p50 and p65 might provide insights into the mechanisms of NF-kappaB action and anti-TNF-alpha therapy in AS.

Protein isoprenylation regulates secretion of matrix metalloproteinase 1 from rheumatoid synovial fibroblasts: Effects of statins and farnesyl and geranylgeranyl transferase inhibitors

OBJECTIVE

To determine whether protein prenylation (farnesyl/geranylgeranylation) regulates matrix metalloproteinase (MMP) secretion from rheumatoid arthritis (RA) synovial fibroblasts (RASFs), and whether MMP-1 secretion can be regulated by statins or prenyltransferase inhibitors via effects mediated by ERK, JNK, and NF-kappaB.

METHODS

RASFs obtained from patients during elective knee replacement surgery were assessed by immunoblotting and/or enzyme-linked immunosorbent assay for secretion of MMP-1 and MMP-13 in the presence of tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), statins, the farnesyl transferase (FT) inhibitor FTI-276 and geranylgeranyl transferase inhibitor GGTI-298, and prenyl substrates (farnesyl pyrophosphate [FPP] and geranylgeranyl pyrophosphate [GGPP]). Activities of JNK and ERK were determined by phosphoimmunoblotting, and NF-kappaB activation was determined by nuclear translocation of the p65 component.

RESULTS

FTI-276, but not statins, inhibited RASF secretion of MMP-1, but not MMP-13, following induction with TNFalpha (P = 0.0007) or IL-1beta (P = 0.006). Loading RASFs with FPP to promote farnesylation enhanced MMP-1 secretion. FTI-276 inhibited activation of JNK (P < 0.05) and NF-kappaB (P = 0.02), but not ERK. In contrast, GGTI-298 enhanced, while GGPP inhibited, MMP-1 secretion. FTI-276 and GGTI-298 together had no effect on MMP-1 secretion. Stimulation of RASFs with TNFalpha or IL-1beta led to increased expression and activity of FT.

CONCLUSION

Protein farnesylation is required for expression and secretion of MMP-1 from RASFs, via effects on JNK and NF-kappaB. The ability of cytokines to stimulate the expression and activity of FT suggests that FT may be increased in the rheumatoid joint. In contrast, geranylgeranylation down-regulates MMP-1 expression. Statins simultaneously inhibit farnesylation and geranylgeranylation, and in consequence do not inhibit MMP-1 secretion. The ability of FTI-276 to inhibit MMP-1 secretion suggests a potential therapeutic strategy in RA.

Prostaglandin E2 downregulates TNF-α-induced production of matrix metalloproteinase-1 in HCS-2/8 chondrocytes by inhibiting Raf-1/MEK/ERK cascade through EP4 prostanoid receptor activation

Matrix metalloproteinase-1 (MMP-1, collagenase-1) plays a pivotal role in the process of joint destruction in degenerative joint diseases. We have examined the regulation of MMP-1 production in human chondrocytic HCS-2/8 cells stimulated by tumor necrosis factor-alpha (TNF-alpha). In response to TNF-alpha, MMP-1 is induced and actively released from HCS-2/8 cells. The induction of MMP-1 expression correlates with activation of ERK1/2, MEK, and Raf-1, and is potently prevented by U0126, a selective inhibitor of MEK1/2 activation. In contrast, SB203580, a selective p38 mitogen-activated protein kinases (MAPK) inhibitor, had no effects on TNF-alpha-induced MMP-1 release. A serine/threonine kinase, Akt was not activated in TNF-alpha-stimulated HCS-2/8 cells. TNF-alpha stimulated the production of PGE(2) in addition to MMP-1 in HCS-2/8 cells. Exogenously added PGE(2) potently inhibited TNF-alpha-induced both MMP-1 production and activation of ERK1/2. The effects of PGE(2) were mimicked by ONO-AE1-329, a selective EP4 receptor agonist but not by butaprost, a selective EP2 agonist. In contrast, blockade of endogenously produced PGE(2) signaling by ONO-AE3-208, a selective EP4 receptor antagonist, enhanced TNF-alpha-induced MMP-1 production. Furthermore, the suppression of MMP-1 production by exogenously added PGE(2) was reversed by ONO-AE3-208. Activation of EP4 receptor resulted in cAMP-mediated phosphorylation of Raf-1 on Ser259, a negative regulatory site, and blocked activation of Raf-1/MEK/ERK cascade. Taken together, these findings indicate that Raf-1/MEK/ERK signaling pathway plays a crucial role in the production of MMP-1 in HCS-2/8 cells in response to TNF-alpha, and that the produced PGE(2) downregulates the expression of MMP-1 by blockage of TNF-alpha-induced Raf-1 activation through EP4-PGE(2) receptor activation.

NF-kappaB and the immune response

One of the primary physiological roles of nuclear factor-kappa B (NF-kappaB) is in the immune system. In particular, NF-kappaB family members control the transcription of cytokines and antimicrobial effectors as well as genes that regulate cellular differentiation, survival and proliferation, thereby regulating various aspects of innate and adaptive immune responses. In addition, NF-kappaB also contributes to the development and survival of the cells and tissues that carry out immune responses in mammals. This review, therefore, describes the role of the NF-kappaB pathway in the development and functioning of the immune system.

An essential role of NF-kappaB in the "tumor-like" phenotype of arthritic synoviocytes

A hallmark of rheumatoid arthritis is the formation of an aggressive, tumor-like structure called pannus that erodes the joint. A major cellular component of the pannus is the fibroblast-like synoviocyte (FLS), whose morphology strikingly resembles that of a transformed cell, but underlying mechanisms of this "transformation" are not known. Here, using animal models of rheumatoid arthritis, we show that arthritic FLS contain a substantial (>30%) fraction of bone marrow-derived precursors that can differentiate in vitro into various mesenchymal cell types, but inflammation prevents the multilineage differentiation. We show that the transcription factor NF-kappaB plays the key role in the repression of osteogenic and adipogenic differentiation of arthritic FLS. Furthermore, we show that specific activation of NF-kappaB profoundly enhances proliferation, motility, and matrix-degrading activity of FLS. We thus propose that arthritic FLS are mesenchymal stem cells whose differentiation is arrested at early stages of differentiation by activation of NF-kappaB.

NF-kappaB as a potential therapeutic target in osteoarthritis and rheumatoid arthritis

The family of nuclear factor-kappaB (NF-kappaB) transcription factors is intimately involved in the regulation of expression of numerous genes in the setting of the inflammatory response. Since inflammatory processes play a fundamental role in the damage of articular tissues, many in vitro and in vivo studies have examined the contribution of components of the NF-kappaB signaling pathways to the pathogenesis of various rheumatic diseases, in particular, of osteoarthritis (OA) and rheumatoid arthritis (RA). Inflammation, cartilage degradation, cell proliferation, angiogenesis and pannus formation are processes in which the role of NF-kappaB is prominent. Consequently, large efforts have been devoted to the study of the pharmacologic modulation of the NF-kappaB pathways. These studies have employed currently available therapeutic agents including non-steroidal anti-inflammatory drugs, corticosteroids, nutraceuticals and disease-modifying anti-rheumatic drugs, as well as novel small molecule inhibitors targeted to specific proteins of the NF-kappaB pathways. In addition, promising strategies such as improved antisense DNA therapy and RNA interference have been examined with encouraging results. However, since NF-kappaB also plays a crucial beneficial role in normal physiology and technical problems for effective gene therapy still remain, further research will be needed before NF-kappaB-aimed strategies become an effective therapy for joint diseases, such as OA and RA.

Differential regulation of matrix degrading enzymes in a TNFalpha-induced model of nucleus pulposus tissue degeneration

Intervertebral disc degeneration occurs commonly and is linked to persistent back pain and the development of disc herniation. The mechanisms responsible for tissue catabolism have not yet been fully elucidated. Previously we characterized an in vitro model of TNFalpha-induced nucleus pulposus degeneration, which demonstrates decreased expression of matrix macromolecules, increased expression of matrix degrading enzymes, and the activation of aggrecanase-mediated proteoglycan degradation [Seguin, C.A., Pilliar, R.M., Roughley, P.J., and Kandel, R.A. 2005. Tumor necrosis factor-alpha modulates matrix production and catabolism in nucleus pulposus tissue. Spine 30: 1940-1948]. This study explores the intracellular pathways activated during TNFalpha-induced matrix degradation. We demonstrate that in nucleus pulposus cells, the p38 and JNK pathways regulate induction of MMP-1 and -3; p38, JNK, and NF-kappaB regulate the induction of MMP-13; and ERK regulates the up-regulation of MT1-MMP mRNA in response to TNFalpha. Induction of ADAMTS-4 and -5 mRNA occurred downstream of NF-kappaB activation. Depletion of tissue proteoglycans was mediated by ERK and NF-kappaB-dependent "aggrecanase" activity, suggesting MT1-MMP and ADAMTS-4 and -5 as effectors of TNFalpha-induced tissue catabolism.

Differential expression of U2AF35 in the arthritic joint of avian reovirus-infected chicks

To identify cell types and genes that are differentially expressed during immunopathogenesis of avian reovirus (ARV)-induced viral arthritis (VA), we inoculated arthrotropic strain S1133 of ARV into 1-day-old broilers, and examined tissue histology as well as RNA expression at different days post-inoculation (PI). Using immunohistochemical staining, we detected many CD68 expressing macrophages in and around the blood vessels of the arthritic joints. By RT-PCR, we found that expression of matrix metalloproteinase-2 (MMP-2) and bone morphogenetic protein-2 (BMP-2) was induced earlier in footpads and hock joints of ARV-infected chickens. By employing suppression subtractive hybridization (SSH) technique and RT-PCR, we further identified that small subunit of U2 snRNP auxiliary factor (U2AF35 or U2AF1) mRNA was differentially induced in the joint of ARV-infected chickens. By in situ hybridization (ISH), mRNA signals of U2AF35 and BMP-2 were located in chondrocytes within/near the epiphyseal plate and secondary center of ossification, and in epidermal cells and dermal fibroblast-like cells of arthritic joints. In addition, U2AF35 mRNA was expressed in the inflammatory infiltrates of the bone marrow of ARV-infected arthritic joints, while MMP-2 was mainly detected in chondrocytes. Interestingly, among U2AF35, MMP-2, and BMP-2 that were differentially expressed in the joint of ARV-infected chickens, only U2AF35 induction correlated well with arthritic manifestation. Because U2AF35 may assist in mRNA splicing of proinflammatory chemokines and cytokines, our results indicated that U2AF35 induction might play an immunopathological role in ARV-induced arthritis. This study has first associated U2AF35 to viral arthritis.

Allele-specific MMP-3 transcription under in vivo conditions

A common matrix metalloproteinases-3 (MMP-3) -1612 5A/6A promoter polymorphism is associated with risk for cardiovascular disease, rheumatoid arthritis, and other diseases. Here we used the haplotype chromatin immunoprecipitation method to study allele-specific MMP-3 expression under in vivo conditions in heterozygous THP-1 cells. Pyrosequencing was used to analyse the ratio of 5A-allele to 6A-allele after chromatin immunoprecipitation using an antibody against phosphorylated active RNA polymerase II. There was no allele-specific difference in transcriptional activity during basal conditions, i.e., in unstimulated monocytic THP-1 cells. However, after stimulation of MMP-3 expression by monocyte differentiation or incubation with IL-1beta, the haplotype containing the 5A-allele was associated with higher transcriptional activity compared with the 6A-containing haplotype. Electromobility shift assay demonstrated increased binding of nuclear proteins to the 5A-allele after monocyte differentiation. In conclusion, the common MMP-3 5A/6A promoter polymorphism appears to be functional only during specific environmental conditions involving inflammation.

The inhibitory effects of eckol and dieckol from Ecklonia stolonifera on the expression of matrix metalloproteinase-1 in human dermal fibroblasts

In order to develop new anti-photoaging agents, we examined the inhibitory effects of 29 seaweed extracts on transcriptional activities of NF-kappaB and AP-1, and MMP-1 expression. The extracts from 3 species of Alariaceae, Eisenia bicyclis, Ecklonia cava and Ecklonia stolonifera, have showed strong inhibition of both NF-kappaB and AP-1 reporter activity, which were well correlated with their abilities to inhibit MMP-1 expression. In addition, MMP-1 expression was dramatically attenuated by treatment with eckol or dieckol which were purely isolated from E. stolonifera, indicating that these compounds are active principles to inhibit MMP-1 expression in human dermal fibroblasts. Taken together, our data demonstrate the inhibitory effect of eckol and dieckol from Ecklonia species on MMP-1 expression in human dermal fibroblasts and provide a possibility to develop as an agent for the prevention and treatment of skin aging.

Estrogen receptor alpha regulates matrix metalloproteinase-13 promoter activity primarily through the AP-1 transcriptional regulatory site

Many females develop bone diseases such as osteoporosis, and joint diseases such as osteoarthritis after menopause when estrogen levels decline. As estrogen receptors (ER) are present in such tissues, it is possible that the loss of estrogen at menopause influences the expression of enzymes such as members of the MMP family of proteinases to affect bone and connective tissue metabolism. The present study was undertaken to assess a possible relationship between ER-alpha and MMP-13 expression at the promoter level, and to determine how such a relationship could be modulated by ligands such as estrogen. Using a rabbit synovial cell line lacking endogenous ER, a transient transfection system with an ER-alpha construct, and a series of MMP-13 promoter-luciferase constructs of varying lengths and with specific mutations in transcription factor binding sites, it was found that ER-alpha can significantly enhance MMP-13 promoter activity via the AP-1 site, with modulatory influences by the Runx and PEA-3 sites on this ER-alpha dependent enhancement of the promoter activity. This enhancement by ER-alpha was significantly depressed in the presence of 17-ss-estradiol in a dose dependent manner. The influence of tamoxifen and raloxifen on the activity of the ER-alpha was consistent with their known agonist/antagonist activity. These findings indicate that loss of estrogen in vivo could potentially lead to enhanced expression of MMP-13, a proteinase that has been implicated in both osteoporosis and osteoarthritis, and thus contribute to the development and progression of these conditions.

Reciprocal interactions between adhesion receptor signaling and MMP regulation

A predominant characteristic of metastatic cells is the ability to invade host tissues and establish distant metastatic foci. Release of metastatic cells from a primary tumor results from disruption of tissue architecture and requires reversible modulation of cell-matrix and cell-cell contacts, cytoskeletal rearrangement, and acquisition of enhanced proteolytic potential. Malignant cells produce a spectrum of extracellular proteinases including matrix metalloproteinases (MMPs) that process extracellular matrix components, cell surface proteins, and immune modulators. Dysregulated proteolysis has been implicated in tumor invasion and metastasis in multiple model systems. This review will focus on data that highlight the influence of cell-matrix and cell-cell interactions and their associated signal transduction pathways on proteinase regulation. These data highlight cell adhesion signaling as a mechanism for a versatile cellular proteolytic response to changing microenvironmental cues.

Activation by IL-1 of bovine articular chondrocytes in culture within a 3D collagen-based scaffold. An in vitro model to address the effect of compounds with therapeutic potential in osteoarthritis

OBJECTIVE

To determine the best protocol for the preparation of a tissue-engineered cartilage to investigate the potential anti-arthritic and/or anti-osteoarthritic effects of drugs.

METHODS

Calf articular chondrocytes, seeded in collagen sponges were grown in culture for up to 1 month. At day 14 cultures received interleukin (IL)-1beta (ranging from 0.1 to 20 ng/ml) for 1 to 3 days. Analyses of gene expression for extracellular matrix proteins, collagen-binding integrins, matrix metalloproteinases (MMPs), aggrecanases, TIMPs, IL-1Ra and Ikappa-Balpha were carried out using real-time polymerase chain reaction (PCR). Metalloproteinase activities were analysed in the culture medium using both zymography and fluorogenic peptide substrates.

RESULTS

We selected a culture for 15 or 17 days with collagen sponges seeded with 10(7) chondrocytes showing a minimal cell proliferation, a maximal sulphated glycosaminoglycan (sGAG) deposition and a high expression of COL2A1, aggrecan and the alpha10 integrin sub-unit and low expression of COL1A2 and the alpha11 integrin sub-unit. In the presence of 1 ng/ml IL-1beta, we observed at day 15 up-regulations of 450-fold for MMP-1, 60-fold for MMP-13, 54-fold for ADAMTS-4 and MMP-3 and 10-fold for ADAMTS-5 and IL-1Ra. Down-regulations of 2.5-fold for COL2A1 and aggrecan were observed only at day 17. At the protein level a dose-dependent increase of total MMP-1 and MMP-13 was noted with less than 15% in the active form.

CONCLUSIONS

This in vitro model of chondrocyte culture in three dimensional (3D) seems well adapted to investigate the responses of these cells to inflammatory cytokines and to evaluate the potential anti-inflammatory effects of drugs.

Region-specific constitutive gene expression in the adult porcine meniscus

The knee meniscus exhibits extensive spatial variations in native healing capacity, biochemical composition, and cell morphology that suggest the existence of distinct phenotypes for meniscus cells. Constitutive gene expression levels of appropriate extracellular matrix proteins may serve as useful molecular markers of cellular phenotypes; however, relatively little is known of variations in the gene expression for meniscus cells of different regions of the tissue. The objective of the present study was to evaluate constitutive differences between radial inner and outer regions in gene expression for extracellular matrix proteins relevant to the meniscus. A secondary objective was to determine if these region-specific differences in gene expression are maintained after periods of monolayer culture. The innermost regions of the meniscus were found to constitutively express higher mRNA levels for proteins highly expressed in articular cartilage, including aggrecan, type II collagen, and NOS2. In contrast, the outer meniscus was found to contain higher gene expression for proteins associated with fibrous tissues including type I collagen, and the proteases MMP2 and MMP3. Isolated inner and outer meniscus cells maintained these region-specific gene expression patterns for collagens and proteoglycans during short-term monolayer culture. The results provide new information that suggests the utility of constitutive gene expression levels as molecular markers to distinguish tissue and cells of the inner and outer meniscus.

Bioactive sphingolipids in the modulation of the inflammatory response

Inflammation is viewed as a protective response against insults to the organism. It involves the recruitment of many cell types and the production of various inflammatory mediators in attempts to contain and reverse the insult. However, inflammation can lead to irreversible tissue destruction by itself and, therefore, can represent a disease state that causes significant morbidity and mortality. Understanding the molecular mechanisms controlling the inflammatory response is essential to formulate therapeutic strategies for the treatment of inflammatory conditions. In fact, substantial research has unveiled important aspects of the inflammatory machinery, both at the cellular and molecular levels. Recently, sphingolipids (SLs) have emerged as signaling molecules that regulate many cell functions, and ample evidence emphasizes their role in the regulation of inflammatory responses. Here, we review the role of bioactive SL as regulators and mediators of inflammatory responses.

Prostaglandin E2 stimulates p53 transactivational activity through specific serine 15 phosphorylation in human synovial fibroblasts. Role in suppression of c/EBP/NF-kappaB-mediated MEKK1-induced MMP-1 expression

Cyclooxygenase-2 (COX-2) overexpression has been linked to cell survival, transformation, and hyperproliferation. We examined the regulation of the tumor suppressor gene p53 and p53 target genes by prostaglandin E(2) (PGE(2)) in human synovial fibroblasts (HSF). PGE(2) induced a time-dependent increase in p53 Ser(15) phosphorylation, with no discernible change in overall p53 levels. PGE(2)-dependent Ser(15) phosphorylation was apparently mediated by activated p38 MAP kinase as SB202190, a p38 kinase inhibitor, blocked the response. Overexpression of a MKK3 construct, but not MKK1, stimulated SB202190-sensitive p53 Ser(15) phosphorylation. PGE(2)-stimulated [phospho-Ser(15)]p53 transactivated a p53 response element (GADD45)-luciferase reporter in transiently transfected HSF (SN7); the effect was compromised by overexpression of a dominant-negative mutant (dnm) of p53 or excess p53S15A expression plasmid but mimicked by a constitutively active p53S15E expression construct. PGE(2), wtp53 expression in the presence of PGE(2), and p53S15E suppressed steady-state levels of MEKK1-induced MMP-1 mRNA, effects nullified with co-transfection of p53 dnm or p53S15A. MEKK1-induced MMP-1 promoter-driven luciferase activity was largely dependent on a c/EBPbeta-NF-kappaB-like enhancer site at -2008 to -1972 bp, as judged by deletion and point mutation analyses. PGE(2), overexpression of p53wt with PGE(2), or p53S15E abolished the MEKK1-induced MMP-1 promoter luciferase activity. Gel-shift/super gel-shift analyses identified c/EBPbeta dimers and c/EBPbeta/NF-kappaB p65 heterodimers as binding species at the apparent site of MEKK1-dependent transactivation. PGE(2)-stimulated [phospho-Ser(15)]p53 abrogated the DNA binding of c/EBPbeta dimers and c/EBPbeta/NF-kappaB p65 heterodimers. Our data suggest that COX-2 prostaglandins may be implicated in p53 function and p53 target gene expression.

Modulation of autocrine TNF-alpha-stimulated matrix metalloproteinase 9 (MMP-9) expression by mitogen-activated protein kinases in THP-1 monocytic cells

Matrix metalloproteinase 9 (MMP-9) is implicated in various physiological processes by its ability to degrade the extracellular matrix (ECM) and process multiple regulatory proteins. Normally, MMP-9 expression is tightly controlled in cells. Sustained or enhanced MMP-9 secretion, however, has been demonstrated to contribute to the pathophysiology of numerous diseases, including arthritis and tumor progression, rendering this enzyme a major target for clinical interventions. Here we show that constitutive MMP-9 secretion was abrogated in THP-1 monocytic leukemia cells by addition of neutralizing antibodies against tumor necrosis factor alpha (TNF-alpha) or TNF receptor type 1 (TNF-R1), as well as by inhibition of TNF-alpha converting enzyme (TACE). This indicates that MMP-9 production in these cells is maintained by autocrine stimulation, with TNF-alpha acting via TNF-R1. To investigate the intracellular signaling routes involved in MMP-9 gene transcription, cells were treated with different inhibitors of major mitogen-activated protein kinase (MAPK) pathways. Interruption of the extracellular signal-regulated kinase pathway 1/2 (ERK1/2) using PD98059 significantly downregulated constitutive MMP-9 release. In contrast, blockage of p38 kinase activity by addition of SB203580 or SB202190, as well as inhibition of c-Jun N-terminal kinase (JNK) using L-JNK-I1, clearly augmented MMP-9 expression and secretion by an upregulation of ERK1/2 phosphorylation. Moreover, exogenously added TNF-alpha augmented MMP-9 synthesis and secretion in THP-1 cells via enhancement of ERK1/2 activity. Taken together, our results indicate that ERK1/2 activity plays a pivotal role in TNF-alpha-induced MMP-9 production and demonstrate its negative modulation by p38 and JNK activity. These findings suggest ERK1/2 rather than p38 and JNK as a reasonable target to specifically block MMP-9 expression using MAPK inhibitors in therapeutic applications.

Cell interactions between human gingival fibroblasts and monocytes stimulate the production of matrix metalloproteinase-1 in gingival fibroblasts

BACKGROUND

Matrix metalloproteinase-1 (MMP-1) plays an important role in inflammatory diseases including periodontitis, which is characterized by tissue destruction and dense infiltration of mononuclear cells.

OBJECTIVES

The aim of this study was to investigate the effect of cell interactions between human gingival fibroblasts and human monocytes on the production of MMP-1 in a coculture model.

METHODS

The fibroblasts were cultured in either cell-to-cell contact with monocytes or in separated cocultures using a microporous membrane to prevent cell-to-cell contact. The mRNA expression of MMP-1 was analyzed using reverse transcription-polymerase chain reaction (RT-PCR) and the protein levels of MMP-1 in the cell medium were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Coculturing gingival fibroblasts with monocytes in cell-to-cell contact increased the mRNA expression of MMP-1 in both fibroblasts and monocytes. The protein levels of MMP-1 increased in the culture media of the cocultures and correlated to the number of fibroblasts as well as to the number of monocytes. When fibroblasts were cultured with monocytes in separated cocultures, the mRNA expression and protein level of MMP-1 increased in the fibroblasts. In addition, treatment of fibroblasts with conditioned medium from monocytes also stimulated the production of MMP-1 in the fibroblasts. Moreover, the levels of the MMP-1 inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), increased in cocultures with cell-to-cell contact, but not in fibroblasts of separated cocultures. The glucocorticoid dexamethasone and the tetracycline doxycycline reduced the enhanced level of MMP-1 in the cocultures with cell-to-cell contact.

CONCLUSION

The current study demonstrates that monocytes stimulate the production of MMP-1 in gingival fibroblasts by cell interactions, which may contribute to the maintenance of MMP-mediated tissue destruction in periodontitis.

The role of human HtrA1 in arthritic disease

Human HtrA1 belongs to a widely conserved family of serine proteases involved in various aspects of protein quality control and cell fate. Although HtrA1 has been implicated in the pathology of several diseases, its precise biological functions remain to be established. Through identification of potential HtrA1 targets, studies presented herein propose that within the context of arthritis pathology HtrA1 contributes to cartilage degradation. Elevated synovial HtrA1 levels were detected in fluids obtained from rheumatoid and osteoarthritis patients, with synovial fibroblasts identified as a major source of secreted HtrA1. Mass spectrometry analysis of potential HtrA1 substrates within synovial fluids identified fibronectin as a candidate target, and treatment of fibronectin with recombinant HtrA1 led to the generation of fibronectin-degradation products that may be involved in cartilage catabolism. Consistently, treatment of synovial fibroblasts with HtrA1 or HtrA1-generated fibronectin fragments resulted in the specific induction of matrix metalloprotease 1 and matrix metalloprotease 3 expression, suggesting that HtrA1 contributes to the destruction of extracellular matrix through both direct and indirect mechanisms.

Resolution of inflammation: prostaglandin E2 dissociates nuclear trafficking of individual NF-kappaB subunits (p65, p50) in stimulated rheumatoid synovial fibroblasts

NF-kappaB transcription factors regulate inflammatory responses to cytokines such as IL-1beta and TNF-alpha. We tested whether PGE2 regulated nuclear localization of individual NF-kappaB subunits, p65 and p50, in synovial fibroblasts harvested from patients with rheumatoid arthritis (RA). IL-1beta/TNF-alpha stimulated the translocation of p65 and p50 from the cytosol to the nucleus of human RA synovial fibroblasts, as well as NF-kappaB activation measured by luciferase reporter assay. PGE2 (10 nM, 6 h) enhanced p50, but inhibited p65 translocation and NF-kappaB activation. In contrast, depletion of endogenous PGE2 by ibuprofen (100 microM) and celecoxib (5 microM) enhanced p65, but inhibited p50 nuclear translocation as well as binding to NF-kappaB DNA binding sites. PGE2 also blocked IL-1beta/TNF-alpha-stimulated ERK activation, and the ERK inhibitor, PD98059, mimicked PGE2 in blocking p65, but enhancing p50 nuclear translocation, suggesting that the effects of PGE2 on p65 and p50 are mediated via effects on ERK. PGE2 also enhanced the expression of IkappaBalpha in an ERK-independent manner, suggesting that PGE2 inhibits NF-kappaB activation by both ERK-dependent and -independent mechanisms. Our data indicate that PGE2 may act to attenuate cytokine-induced inflammatory responses in RA synovial fibroblasts via regulation of the localization of specific NF-kappaB family dimers.

Interleukin-1 beta induction of matrix metalloproteinase-1 transcription in chondrocytes requires ERK-dependent activation of CCAAT enhancer-binding protein-beta

Interleukin-1 beta (IL-1beta) is a central mediator of inflammation and connective tissue destruction in rheumatoid arthritis. IL-1beta activates articular chondrocytes to produce matrix metalloproteinase-1 (MMP-1), an enzyme capable of dismantling the collagen scaffold of articular cartilage. To define the transcription factors and signaling intermediates that activate MMP-1 transcription in chondrocytes, we performed transient transfection of MMP-1 promoter constructs followed by reporter assays. These studies identified an IL-1beta-responsive region of the human MMP-1 promoter that contains a consensus CCAAT enhancer-binding protein (C/EBP) binding site. Deletion of this site reduced overall transcriptional activity of the MMP-1 promoter, as well as decreased fold induction by IL-1beta. IL-1beta stimulation of chondrocytes increased binding of C/EBP-beta to the MMP-1 C/EBP site. Extracellular signal regulated kinase (ERK) pathway-dependent phosphorylation of C/EBP-beta on threonine 235 activates this transcription factor. Here we show that IL-1beta stimulation of chondrocytes induced phosphorylation of C/EBP-beta on threonine 235, and that the ERK pathway inhibitor PD98059 reduced this phosphorylation. We further show that PD98059 reduces IL-1beta-induced MMP-1 mRNA expression in chondrocytes. Moreover, inhibition of the ERK pathway by expression of dominant-negative forms of ERK1 and ERK2 impaired the ability of IL-1beta to transactivate the MMP-1 promoter. Our findings demonstrate a novel role for C/EBP-beta in IL-1beta-induced connective tissue disease and define a new nuclear target for the ERK pathway in MMP-1 gene activation.

Posttranscriptional mechanisms regulating the inflammatory response

The inflammatory response is a complex physiologic process that requires the coordinate induction of cytokines, chemokines, angiogenic factors, effector-enzymes, and proteases. Although transcriptional activation is required to turn on the inflammatory response, recent studies have revealed that posttranscriptional mechanisms play an important role by determining the rate at which mRNAs encoding inflammatory effector proteins are translated and degraded. Most posttranscriptional control mechanisms function to dampen the expression of pro-inflammatory proteins to ensure that potentially injurious proteins are not overexpressed during an inflammatory response. Here we discuss the factors that regulate the stability and translation of mRNAs encoding pro-inflammatory proteins.

Contribution of runt-related transcription factor 2 to the pathogenesis of osteoarthritis in mice after induction of knee joint instability

OBJECTIVE

By producing instability in mouse knee joints, we attempted to determine the involvement of runt-related transcription factor 2 (RUNX-2), which is required for chondrocyte hypertrophy, in the development of osteoarthritis (OA).

METHODS

An experimental mouse OA model was created by surgical transection of the medial collateral ligament and resection of the medial meniscus of the knee joints of heterozygous RUNX-2-deficient (Runx2+/-) mice and wild-type littermates. Cartilage destruction and osteophyte formation in the medial tibial cartilage were compared by histologic and radiographic analyses. Localization of type X collagen and matrix metalloproteinase 13 (MMP-13) was examined by immunohistochemistry. Localization of RUNX-2 was determined by X-Gal staining in heterozygous RUNX-2-deficient mice with the lacZ gene insertion at the Runx2-deletion site (Runx2+/lacZ). Messenger RNA levels of type X collagen, MMP-13, and RUNX-2 were examined by real-time reverse transcriptase-polymerase chain reaction analysis.

RESULTS

RUNX-2 was induced in the articular cartilage of wild-type mice at the early stage of OA, almost simultaneously with type X collagen but earlier than MMP-13. Runx2+/- and Runx2+/lacZ mice showed normal skeletal development and articular cartilage; however, after induction of knee joint instability, they exhibited decreased cartilage destruction and osteophyte formation, along with reduced type X collagen and MMP-13 expression, as compared with wild-type mice.

CONCLUSION

RUNX-2 contributes to the pathogenesis of OA through chondrocyte hypertrophy and matrix breakdown after the induction of joint instability.

Mammalian expression of full-length bovine aggrecan and link protein: formation of recombinant proteoglycan aggregates and analysis of proteolytic cleavage by ADAMTS-4 and MMP-13

Aggrecan, a large chondroitin sulfate (CS) and keratan sulfate (KS) proteoglycan, has not previously been expressed as a full-length recombinant molecule. To facilitate structure/function analysis, we have characterized recombinant bovine aggrecan (rbAgg) and link protein expressed in COS-7 cells. We demonstrate that C-terminally truncated rbAgg was not secreted. Gel filtration chromatography of rbAgg and isolated glycosaminoglycan (GAG) chains, and their susceptibility to chondroitinase ABC digestion indicate that the GAG chains are predominantly CS, which likely occupy fewer serine residues than native aggrecan. To confirm functionality, we determined that rbAgg bound hyaluronan and recombinant link protein to form proteoglycan aggregates. In addition, cleavage of rbAgg by ADAMTS-4 revealed that the p68 form of ADAMTS-4 preferentially cleaves within the CS-2 domain, whereas the p40 form only effectively cleaves within the interglobular domain (IGD). MMP-13 cleaved rbAgg within the IGD, but cleaved more rapidly at a site within the CS domains, suggesting a role in C-terminal processing of aggrecan. Our results demonstrate that recombinant aggrecan can be used for in vitro analyses of matrix protease-dependent degradation of aggrecan in the IGD and CS domains, and both recombinant aggrecan and link protein can be used to study the assembly of proteoglycan aggregates with hyaluronan.

Oxidative stress augments the production of matrix metalloproteinase-1, cyclooxygenase-2, and prostaglandin E2 through enhancement of NF-kappa B activity in lipopolysaccharide-activated human primary monocytes

The excessive production of reactive oxidative species (ROS) associated with inflammation leads to a condition of oxidative stress. Cyclooxygenase-2 (COX-2), PGE(2), and matrix metalloproteinases (MMPs) are important mediators during the process of inflammation. In this paper we report on studies examining how the ROS hydrogen peroxide (H(2)O(2)) affects the production of MMP-1, COX-2, and PGE(2). Addition of H(2)O(2) to LPS-activated monocytes, but not naive monocytes, caused a significant enhancement of the LPS-induced production of MMP-1, COX-2, and PGE(2). The mechanism by which H(2)O(2) increased these mediators was through enhancement of IkappaBalpha degradation, with subsequent increases in NF-kappaB activation and NF-kappaB p50 translocation to the nucleus. The effects of H(2)O(2) on IkappaBalpha degradation, NF-kappaB activation, and NF-kappaB p50 localization to the nucleus were demonstrated through studies of coimmunoprecipitation of IkappaBalpha with p50, ELISA of NF-kappaB p65 activity, and Western blot analysis of the nuclear fraction extract for p50. The key role for NF-kappaB in this process was demonstrated by the ability of MG-132 or lactacystin (proteasome inhibitors) to block the enhanced production of MMP-1, COX-2, and PGE(2). In contrast, indomethacin, which inhibited PGE(2) production, partially blocked the enhanced MMP-1 production. Moreover, although PGE(2) restored MMP-1 production in indomethacin-treated monocyte cultures; it failed to significantly restore MMP-1 production in proteasome inhibitor-treated cultures. Thus, in the presence of LPS and H(2)O(2), NF-kappaB plays a dominate role in the regulation of MMP-1, COX-2, and PGE(2) expression.

Expression profiling of human fetal growth plate cartilage by EST sequencing

The differentiation of mesenchymal stem cells into hypertrophic chondrocytes is an integral and multistep process important in pattern formation, endochondral ossification, and postnatal growth of the skeleton. In recent years, novel genes involved in these processes have been identified, but still only little is known about the large-scale gene expression profile during skeletal development. We initiated an expressed sequence tag (EST) project aiming at the identification of genes and pathways involved in this complex process. Candidate genes are expected to be of value for diagnosis and treatment of monogenic and multigenic heritable disorders of the skeleton. Here, we describe the sequences of 4,748 clones from a human growth plate cartilage cDNA library generated from 20 weeks prenatal-2 years postnatal specimens. In silico analysis of these sequences revealed 1,688 individual transcription units, corresponding to known (1,274) and to novel, yet uncharacterised potential genes (414). The tissue specificity of the library was reflected by its corresponding EST profile representing a total of approximately 10% proteins already shown to be involved in cartilage/bone development or homeostasis. The EST profile also reflects the developmental stage of the tissue with significant differences in the expression of matrix proteins compared to corresponding EST profiles from 8-12 and 12-20 week human fetal cartilage. Calculation of the relative frequency of transcripts in our cDNA library, as compared to their abundance in other EST datasets, revealed a set of approximately 200 genes, including 81 novel, yet uncharacterised genes, showing increased expression. These genes represent candidates for the large number of osteochondrodysplasias for which the causative gene defects have not yet been identified.

Dihydrosphingosine 1-phosphate stimulates MMP1 gene expression via activation of ERK1/2-Ets1 pathway in human fibroblasts

Sphingosine kinase (SphK) is a conserved lipid kinase that catalyzes formation of important regulators of inter- and intracellular signaling, sphingosine-1 phosphate (S1P), and dihydrosphingosine 1-phosphate (dhS1P). In this study, we investigated the role of SphK1 in the regulation of expression of matrix metalloproteinase 1 (MMP1) in dermal fibroblasts, a key event in regulation of extra cellular matrix. We show that overexpression of SphK1 up-regulated MMP1 protein, MMP1 mRNA, and MMP1 promoter activity, and this action of SphK1 required activation of the ERK1/2-Ets1 and NF-kappaB pathways. Furthermore, experiments using SphK1 specific siRNA demonstrated that SphK1 is required for the TNF-alpha stimulation of MMP1. Additional data revealed a specific role of dhS1P, and not S1P, as a mediator of SphK1-dependent activation of ERK1/2 and up-regulation of MMP1. The stimulatory effect of dhS1P was sensitive to pertussis toxin, suggesting a possible involvement of a G-protein-coupled receptor. In contrast, S1P, but not dhS1P, stimulated the induction of COX-2, which demonstrated selective actions of these two closely related bioactive lipids. In conclusion, this study describes a novel mode of SphK1 signaling through generation of dhS1P with a key role in mediating transcriptional responses to TNF-alpha. This is the first report of selective function of dhS1P as compared with the better studied S1P.

Cell expression of MMP-1 and TIMP-1 in co-cultures of human gingival fibroblasts and monocytes: the involvement of ICAM-1

Matrix metalloproteinase-1 (MMP-1) plays an important role in the degradation of collagen in inflammatory diseases. The aim of this study was to investigate the cellular expression of MMP-1 and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), in gingival fibroblasts co-cultured with monocytes and the possible mediating role of intercellular adhesion molecule-1 (ICAM-1). In co-cultures, the expression of MMP-1 and TIMP-1 increased in fibroblasts, but not in monocytes, although the number of MMP-1+ and TIMP-1+ adhered monocytes increased. Moreover, ICAM-1 expression in both fibroblasts and adhered monocytes increased. In the presence of an anti-ICAM-1 antibody, the expression of MMP-1 in fibroblasts decreased whereas the number of TIMP-1+ adhered monocytes increased. The p38 MAPK inhibitor SB203580 reduced MMP-1 expression in fibroblasts, as well as ICAM-1 expression in both fibroblasts and adhered monocytes. The results suggest that co-culture with monocytes enhances cellular expression of MMP-1 and TIMP-1 in gingival fibroblasts, and that the increased MMP-1 expression, in contrast to TIMP-1, is partly mediated by the adhesion molecule ICAM-1 and the p38 MAPK signal pathway.

Effects of glucosamine and chondroitin sulfate on mediators of osteoarthritis in cultured equine chondrocytes stimulated by use of recombinant equine interleukin-1beta

OBJECTIVE

To determine whether glucosamine and chondroitin sulfate (CS) at concentrations approximating those achieved in plasma by oral administration would influence gene expression of selected mediators of osteoarthritis in cytokine-stimulated equine articular chondrocytes.

SAMPLE POPULATION

Samples of grossly normal articular cartilage obtained from the metacarpophalangeal joint of 13 horses.

PROCEDURE

Equine chondrocytes in pellet culture were stimulated with a subsaturating dose of recombinant equine interleukin (reIL)-1beta. Effects of prior incubation with glucosamine (2.5 to 10.0 microg/mL) and CS (5.0 to 50.0 microg/mL) on gene expression of matrix metalloproteinase (MMP)-1, -2, -3, -9, and -13; aggrecanase 1 and 2; inducible nitric oxide synthase (iNOS); cyclooxygenase (COX)-2; nuclear factor kappaB; and c-Jun-N-terminal kinase (JNK) were assessed by use of a quantitative real-time polymerase chain reaction assay.

RESULTS

Glucosamine at a concentration of 10 microg/mL significantly reduced reIL-1beta-induced mRNA expression of MMP-13, aggrecanase 1, and JNK. Reductions in cytokine-induced expression were also observed for iNOS and COX-2. Chondroitin sulfate had no effect on gene expression at the concentrations tested.

CONCLUSIONS AND CLINICAL RELEVANCE

Concentrations of glucosamine similar to those achieved in plasma after oral administration in horses exerted pretranslational regulation of some mediators of osteoarthritis, an effect that may contribute to the cartilage-sparing properties of this aminomonosaccharide. Analysis of results of this study indicated that the influence of CS on pretranslational regulation of these selected genes is limited or lacking.

Expression and regulation of antimicrobial peptides in articular joints

Articular joint infection is a surprisingly rare event considering the frequency of joint arthrocentesis and other invasive procedures applied to limb joints. This observation led us to the hypothesis that a local "chemical shield" in the form of antimicrobial proteins provides synovial membrane and articular cartilage with resistance to infection. We subsequently began a systematic analysis of in vitro and in vivo antimicrobially active proteins in healthy articular joints and in disease states such as pyogenic arthritis, rheumatoid arthritis, and osteoarthritis. An anatomical approach with systematic characterization combined with antimicrobial testing revealed expression and production of human antibiotic peptides and proteins. In this review, we focus on the most prominent antimicrobial proteins in articular joints, which we have identified as lysozyme, lactoferrin, secretory phospholipase A2, RNase 7, CAP37, the cathelicidin LL37, and especially the human beta-defensin-2 and -3 (HBD-2/-3). Activation pathways and possible antimicrobial functions are discussed and the involvement in non-antimicrobial processes such as tissue remodelling is also considered.

PD-0200347, an alpha2delta ligand of the voltage gated calcium channel, inhibits in vivo activation of the Erk1/2 pathway in osteoarthritic chondrocytes: a PKCalpha dependent effect

OBJECTIVE

To explore the in vivo effects of PD-0200347, an alpha(2)delta ligand of voltage gated Ca(2+) channels, on cell signalling in osteoarthritic (OA) chondrocytes from an experimental dog model, and examine the effect of PD-0200347 on the major signalling pathways involved in OA cartilage degradation.

METHODS

OA was surgically induced in dogs by sectioning the anterior cruciate ligament. OA dogs were divided into three groups and treated orally with (a) placebo; (b) 15 mg/kg/day PD-0200347, or (c) 90 mg/kg/day PD-0200347. The animals were killed 12 weeks after surgery. Cartilage specimens from femoral condyles and tibial plateaus were processed for immunohistochemistry. Specific antibodies against the phosphorylated form of PKCalpha, Ras, c-Raf, the MAP kinases Erk1/2, p38, JNK, and the transcription factors, CREB and Elk-1, were used.

RESULTS

Levels of all the tested signalling mediators were increased in the placebo treated (OA) group compared with the normal group. PD-0200347 treatment significantly reduced the levels of the active forms of PKCalpha, c-Raf, Erk1/2, and Elk-1; however, the levels of the active forms of Ras, p38, JNK, and CREB were not affected by the PD-0200347 treatment.

CONCLUSION

The action of PD-0200347 on OA chondrocytes is probably mediated through the inhibition of Erk1/2 activation via a Ras independent mechanism. This effect is associated with reduction of the activation of transcription factors such as Elk-1, which leads to the inhibition of the induction of the major catabolic factors involved in the degradation process of OA cartilage.

Polyamine depletion inhibits NF-kappaB binding to DNA and interleukin-8 production in human chondrocytes stimulated by tumor necrosis factor-alpha

The activation of the NF-kappaB pathway by pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNFalpha), can be an important contributor for the re-programming of chondrocyte gene expression, thereby making it a therapeutic target in articular diseases. To search for new approaches to limit cartilage damage, we investigated the requirement of polyamines for NF-kappaB activation by TNFalpha in human C-28/I2 chondrocytes, using alpha-difluoromethylornithine (DFMO), a specific polyamine biosynthesis inhibitor. The NF-kappaB pathway was dissected by using pharmacological inhibitors or by expressing a transdominant IkappaBalpha super repressor. Treatment of C-28/I2 chondrocytes with TNFalpha resulted in a rapid enhancement of nuclear localization and DNA binding activity of the p65 NF-kappaB subunit. TNFalpha also increased the level and extracellular release of interleukin-8 (IL-8), a CXC chemokine that can have a role in arthritis, in an NF-kappaB-dependent manner. Pre-treatment of chondrocytes with DFMO, while causing polyamine depletion, significantly reduced NF-kappaB DNA binding activity. Moreover, DFMO also decreased IL-8 production without affecting cellular viability. Restoration of polyamine levels by the co-addition of putrescine circumvented the inhibitory effects of DFMO. Our results show that the intracellular depletion of polyamines inhibits the response of chondrocytes to TNFalpha by interfering with the DNA binding activity of NF-kappaB. This suggests that a pharmacological and/or genetic approach to deplete the polyamine pool in chondrocytes may represent a useful way to reduce NF-kappaB activation by inflammatory cytokines in arthritis without provoking chondrocyte apoptosis.

Effect of cobalt and chromium ions on MMP-1, TIMP-1, and TNF-α gene expression in human U937 macrophages: A role for tyrosine kinases

Previous reports have suggested that the imbalance of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) activity may contribute to prosthetic loosening. However, the mechanisms controlling these enzymes in the periprosthetic environment is unknown. We examined the effect of Co2+ and Cr3+ ions on the expression of genes encoding MMP-1, one of the principal proteinases capable of degrading native fibrillar collagens in the extracellular matrix (ECM), its inhibitor TIMP-1, and TNF-alpha, a cytokine that plays a central role in the induction of implant osteolysis. Human U937 macrophages were incubated in suspension or on phosphorylcholine (PC)-polymer coated surfaces for 24h with Co2+ and Cr3+ ions. The level of mRNAs was determined by reverse transcription-polymerase chain reaction (RT-PCR). Results show that both Co2+ and Cr3+ ions induce the expression of MMP-1, TIMP-1, and TNF-alpha mRNA in a dose-dependent manner in cell suspensions. Tyrosine kinase inhibitors have different effects on these stimulatory effects. Indeed, genistein has only partial inhibitory effect on MMP-1 and TIMP-1, with even less effect on TNF-alpha expression. In contrast, herbimycin A completely blocks MMP-1 and TNF-alpha while partially inhibiting TIMP-1. However, Co2+ and Cr3+ ions had no effect on the expression of MMP-1 and TIMP-1 in macrophages cultured on the PC-polymer, suggesting that the attachment of U937 macrophages to the PC-polymer surfaces may modify their gene expression. In fact, MMP-1 and TIMP-1 seems to be constitutively up-regulated in this condition. However, the effect of Co2+ and Cr3+ ions on macrophages cultured on PC-polymer coated surfaces is similar to what was observed in suspension. Together, these findings indicate that activation of MMP-1, TIMP-1, and TNF-alpha by Co2+ and Cr3+ ions is regulated by tyrosine kinases.

Human beta-defensin 3 mediates tissue remodeling processes in articular cartilage by increasing levels of metalloproteinases and reducing levels of their endogenous inhibitors

OBJECTIVE

Beta-defensins are broad-spectrum antimicrobial peptides (APs) that are components of innate immunity. Recent investigations showed the induction of beta-defensins in synovial membranes of osteoarthritic (OA) joints and suggested that they have functions other than the ability to kill microbes. As a result of these findings, we undertook this study to investigate the production of human beta-defensin 3 (HBD-3) in OA cartilage and to determine its influence on chondrocyte function.

METHODS

Healthy and OA cartilage were assessed for HBD-3 expression by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. HBD-3 expression in C28/I2 chondrocytes after administration of tumor necrosis factor alpha (TNFalpha) and interleukin-1 (IL-1) was determined by real-time RT-PCR and immunodot blot. Enzyme-linked immunosorbent assay experiments were used to study the effects of HBD-3 in cultured articular chondrocytes and in healthy and OA cartilage discs. Immunohistochemical analyses were performed to study the expression of mouse beta-defensins (MBDs) in OA cartilage of STR/Ort mice.

RESULTS

HBD-3 was induced in OA cartilage without bacterial challenge. Cytokines involved in the pathogenesis of OA, namely, TNFalpha and IL-1, were strong inducers of HBD-3 in cultured chondrocytes. Application of the recombinant HBD-3 protein to cultured chondrocytes and cartilage discs resulted in increased production of cartilage-degrading matrix metalloproteinases and in down-regulation of their endogenous regulators, tissue inhibitors of metalloproteinases 1 and 2. Furthermore, STR/Ort mice, which are genetically predisposed to develop OA-like lesions in the knee joint, demonstrated an increased expression of MBDs 3 and 4 in cartilage compared with that in healthy animals.

CONCLUSION

These findings widen our knowledge of the functional spectrum of APs and demonstrate that HBD-3 is a multifunctional AP with the ability to link host defense mechanisms and inflammation with tissue-remodeling processes in articular cartilage. Moreover, our data suggest that HBD-3 is an additional factor in the pathogenesis of OA.

Contrasting effects of fluoroquinolone antibiotics on the expression of the collagenases, matrix metalloproteinases (MMP)-1 and -13, in human tendon-derived cells

OBJECTIVES

Fluoroquinolone antibiotics may cause tendon pain and rupture. We reported previously that the fluoroquinolone ciprofloxacin potentiated interleukin (IL)-1beta-stimulated expression of matrix metalloproteinases (MMP)-3 and MMP-1 in human tendon-derived cells. We have now tested additional fluoroquinolones and investigated whether they have a similar effect on expression of MMP-13.

METHODS

Tendon cells were incubated for two periods of 48 h with or without fluoroquinolones and IL-1beta. Total ribonucleic acid (RNA) was assayed for MMP messenger RNA by relative quantitative reverse transcriptase polymerase chain reaction, with normalization for glyceraldehyde-3-phosphate dehydrogenase mRNA. Samples of supernatant medium were assayed for MMP output by activity assays.

RESULTS

MMP-13 was expressed by tendon cells at lower levels than MMP-1, and was stimulated typically 10- to 100-fold by IL-1beta. Ciprofloxacin, norfloxacin and ofloxacin each reduced both basal and stimulated expression of MMP-13 mRNA. In contrast, ciprofloxacin and norfloxacin increased basal and IL-1beta-stimulated MMP-1 mRNA expression. Both the inhibition of MMP-13 and the potentiation of MMP-1 expression by fluoroquinolones were accompanied by corresponding changes in IL-1beta-stimulated MMP output. The non-fluorinated quinolone nalidixic acid had lesser or no effects.

CONCLUSIONS

Fluoroquinolones show contrasting effects on the expression of the two collagenases MMP-1 and MMP-13, indicating specific effects on MMP gene regulation.

Punica granatum L. extract inhibits IL-1beta-induced expression of matrix metalloproteinases by inhibiting the activation of MAP kinases and NF-kappaB in human chondrocytes in vitro

Interleukin (IL)-1beta induces the expression of matrix metalloproteinases (MMPs) implicated in cartilage resorption and joint degradation in osteoarthritis (OA). Pomegranate fruit extract (PFE) was recently shown to exert anti-inflammatory effects in different disease models. However, no studies have been undertaken to investigate whether PFE constituents protect articular cartilage. In the present studies, OA chondrocytes or cartilage explants were pretreated with PFE and then stimulated with IL-1beta at different time points in vitro. The amounts of proteoglycan released were measured by a colorimetric assay. The expression of MMPs, phosphorylation of the inhibitor of kappaBalpha (IkappaBalpha) and mitogen-activated protein kinases (MAPKs) was determined by Western immunoblotting. Expression of mRNA was quantified by real-time PCR. MAPK enzyme activity was assayed by in vitro kinase assay. Activation of nuclear factor-kappaB (NF-kappaB) was determined by electrophoretic mobility shift assay. PFE inhibited the IL-1beta-induced proteoglycan breakdown in cartilage explants in vitro. At the cellular level, PFE (6.25-25 mg/L) inhibited the IL-1beta-induced expression of MMP-1, -3, and -13 protein in the medium (P < 0.05) and this was associated with the inhibition of mRNA expression. IL-1beta-induced phosphorylation of p38-MAPK, but not that of c-Jun-N-terminal kinase or extracellular regulated kinase, was most susceptible to inhibition by low doses of PFE, and the addition of PFE blocked the activity of p38-MAPK in a kinase activity assay. PFE also inhibited the IL-1beta-induced phosphorylation of IkappaBalpha and the DNA binding activity of the transcription factor NF-kappaB in OA chondrocytes. Taken together, these novel results indicate that PFE or compounds derived from it may inhibit cartilage degradation in OA and may also be a useful nutritive supplement for maintaining joint integrity and function.

Novel p38 mitogen-activated protein kinase inhibitor R-130823 protects cartilage by down-regulating matrix metalloproteinase-1,-13 and prostaglandin E2 production in human chondrocytes

In order to study the involvement of mitogen-activated protein kinase p38 in osteoarthritis, we investigated the effect of novel p38 inhibitor R-130823 {2-(4-fluorophenyl)-4-(1-phenethyl-1,2,3,6-tetrahydropyridin-4-yl)-3-(pyridin-4-yl)-1H-pyrrole} on human chondrocytes and bovine cartilage. In human primary chondrocytes, the production of matrix metalloproteinase-13 and -1 (MMP-13 and -1) and prostaglandin E2 (PGE2) was induced by interleukin-1beta. Pretreatment with R-130823 inhibited the release of MMP-13, MMP-1 and PGE2 with IC50 values of 20, 230 and 3.9 nM, respectively. The inhibitory activity was also confirmed by a decrease in MMP-13 release from human chondrosarcoma cell line SW1353 with an IC50 value of 17 nM. Ribonuclease protection assay on human primary chondrocytes indicated that MMP-13 and MMP-1 mRNA levels almost reached the maximum 14 h after IL-1 stimulation, while cyclooxygenase-2 (COX-2) mRNA quickly reached the maximum 4 h after the stimulation. R-130823 down-regulated the steady-state levels of MMP-13 and MMP-1 mRNA with IC50 values of 4.2 and 79 nM, respectively. The COX-2 mRNA level was also suppressed with an IC50 value of 21 nM. In the explant culture of bovine nasal cartilage, R-130823 suppressed the collagen cleavage induced by interleukin-1alpha and oncostatin M, but not IL-1beta-mediated glycosaminoglycan release. These results suggest that activated p38 accelerates cartilage breakdown by enhancing the expression of MMPs responsible for collagen cleavage, which thus implies chondroprotective effects of p38 inhibitors in osteoarthritis.

Cyclosporin a affects signaling events differentially in human gingival fibroblasts

Gingival overgrowth is a common side-effect of the administration of cyclosporin A (CSA), phenytoin, and calcium blockers. To identify the signaling mechanisms possibly involved in the overgrowth, we examined how CSA affects the activities of MAP kinases and transcription factors in human gingival fibroblasts (HGF). The HGF were treated with CSA and TNF-alpha or PDGF. DNA-binding activity of NFAT, NFkappaB, and AP-1 transcription factors was determined by gel shift assay, and JNK, p38, and ERK1 and ERK2 activation was assessed by Western blot analysis of immunoprecipitates. The CSA inhibited NFAT, NFkappaB, and p38 and JNK activities; however, ERK1 and ERK2 were not affected significantly. AP-1 activity increased approximately 4.5-fold. Our results indicate that CSA affects signaling molecules in HGF differently from other cell types, and that a CSA-induced increase in AP-1 activity may affect the expression of fibrogenic molecules in gingiva and promote gingival overgrowth.

Eicosapentaenoic acid inhibits UV-induced MMP-1 expression in human dermal fibroblasts

Ultraviolet (UV) irradiation regulates UV-responsive genes, including matrix metalloproteinases (MMPs). Moreover, UV-induced MMPs cause connective tissue damage and the skin to become wrinkled and aged. Here, we investigated the effect of eicosapentaenoic acid (EPA), a dietary omega-3 fatty acid, on UV-induced MMP-1 expression in human dermal fibroblasts (HDFs). We found that UV radiation increases MMP-1 expression and that this is mediated by p44 and p42 MAP kinase (ERK) and Jun-N-terminal kinase (JNK) activation but not by p38 activation. Pretreatment of HDFs with EPA inhibited UV-induced MMP-1 expression in a dose-dependent manner and also inhibited the UV-induced activation of ERK and JNK by inhibiting ERK kinase (MEK1) and SAPK/ERK kinase 1 (SEK1) activation, respectively. Moreover, inhibition of ERK and JNK by EPA resulted in the decrease of c-Fos expression and c-Jun phosphorylation/expression induced by UV, respectively, which led to the inhibition of UV-induced activator protein-1 DNA binding activity. This inhibitory effect of EPA on MMP-1 was not mediated by an antioxidant effect. We also found that EPA inhibited 12-O-tetradecanoylphorbol-13-acetate- or tumor necrosis factor-alpha-induced MMP-1 expression in HDFs and UV-induced MMP-1 expression in HaCaT cells. In conclusion, our results demonstrate that EPA can inhibit UV-induced MMP-1 expression by inhibiting the MEK1/ERK/c-Fos and SEK1/JNK/c-Jun pathways. Therefore, EPA is a potential agent for the prevention and treatment of skin aging.