metallothionein and Osteoarthritis

OA (Osteoarthritis) is a predominant degenerative disease, characterized by the synovial inflammation and cartilage destruction. The pathogenic mechanisms remain mostly unknown. There is an critical require for extra investigations to discover new therapeutic targets to prevent and treat OA disease, as there are currently no effective treatments except for the joint replacement.. The mRNA and protein levels of Metallothionein-1(MT-1) were quantified by qPCR and ELISA in peripheral blood mononuclear cells (PBMCs), serum and synovial cells (SCs) from erosive inflammatory OA (EIOA) and primary generalized OA (PGOA) patients. Age and sex matched healthy volunteers were recruited as healthy controls (HCs). The correlation between the MT-1 level and OA activity was assessed and the anti-inflammatory effects of MT-1 was determined in vitro.. The mRNA and protein levels of MT-1 were significantly increased in the PBMCs and serum of EIOA patients compared with those of PGOA patients and HCs. Serum levels of MT-1 were positively correlated with VAS score, CRP, and ESR in OA patients. And the positive correlations were also identified between the MT-1 and IL-1β, TNF-α or IL-6 in synovial cells. Furthermore, the recombinant MT-1 protein could significantly inhibit the expression of IL-1β, TNF-α and IL-6 in PBMCs and SCs from EIOA patients in vitro.. The data had shown that the MT-1 was up-regulated in EIOA patients and positively correlated with the disease activity. The recombinant MT-1 could suppress the expression of pro-inflammatory cytokines in both PBMCs and synovial cells from EIOA patients. Therefore, the MT-1 might become a novel therapeutic target for OA treatment.

Topics: Aged; Cells, Cultured; Cytokines; Female; Humans; Leukocytes, Mononuclear; Male; Metallothionein; Middle Aged; Osteoarthritis; Pain Measurement; Synoviocytes

Zinc (Zn) has major effects on immune system activation while Cadmium (Cd) has anti-inflammatory and anti-proliferative effects in several chronic inflammatory contexts. The aim of this work was to investigate by which mechanisms Zn could compete with Cd and eventually counteract its deleterious effects. Rheumatoid arthritis (RA) synoviocytes exposed to cytokines were used as a model of chronic inflammation; osteoarthritis (OA) synoviocytes were used as control.. Cell/medium fractionation constants were analyzed for different metals by inductively-coupled-plasma mass-spectrometry by comparison to the 70Zn spike. Interleukin-17 (IL-17) and tumor necrosis factor-alpha (TNF-α) were used to mimic inflammation. Gene expression of ZIP-8 importer, metallothioneins-1 (MT-1s) and the ratio between metalloprotease-3 and the tissue inhibitor of metalloproteinases (MMP-3)/TIMP-1) were evaluated after pre-exposure to cytokines and Cd, with or without the addition of exogenous Zn (0.9 ppm). Cell viability was measured by neutral red assay and IL-6 production by ELISA.. Synoviocytes selectively absorbed and retained Cd in comparison to Zn. Metal import increased with IL-17/TNF-α exposure, through the enhanced ZIP-8 expression. Zn did not modify ZIP-8 expression, while Cd reduced it (p<0.05). Zn induced a reduction of Cd-induced MT-1s expression, in particular of MT-1X (3-fold), and subsequently the final intra-cellular content of Cd. By reducing Cd accumulation in cells, Zn reversed Cd anti-proliferative and anti-inflammatory effects but preserved the low MMP-3/TIMP-1 ratio induced by Cd, which was enhanced by inflammatory conditions.. Zinc counteracts the deleterious effect of Cd by reducing its import and accumulation in the cell, without the reactivation of destructive pathways such as MMPs.

Topics: Arthritis, Rheumatoid; Biological Transport; Cadmium; Cell Proliferation; Cells, Cultured; Chronic Disease; Humans; Interleukin-17; Matrix Metalloproteinase 3; Metallothionein; Osteoarthritis; Synovial Membrane; Tissue Inhibitor of Metalloproteinase-1; Tumor Necrosis Factor-alpha; Zinc

The zinc-ZIP8-MTF1 axis induces metallothionein (MT) expression and is a catabolic regulator of experimental osteoarthritis (OA) in mice. The main aim of the current study was to explore the roles and underlying molecular mechanisms of MTs in OA pathogenesis.. MTs were highly expressed in human and mouse OA cartilage. Hypoxia-inducible factor 2α, nicotinamide phosphoribosyltransferase and several proinflammatory cytokine pathways, as well as the zinc-ZIP8-MTF1 axis were identified as upstream regulators of MT expression. Genetic deletion of Mt1 and Mt2 enhanced cartilage destruction through increasing chondrocyte apoptosis. Unexpectedly, aberrant overexpression of MT2, but not MT1, induced upregulation of matrix-degrading enzymes and downregulation of matrix molecules through nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1) activation, ultimately leading to OA.. MTs play an antiapoptotic role in post-traumatic OA. However, aberrant and chronic upregulation of MT2 triggers an imbalance between chondrocyte anabolism and catabolism, consequently accelerating OA development. Our findings collectively highlight pleiotropic roles of MTs as regulators of chondrocyte apoptosis as well as catabolic and anabolic pathways during OA pathogenesis.

Topics: Animals; Apoptosis; Arthritis, Experimental; Cartilage, Articular; Chondrocytes; Genetic Pleiotropy; Humans; Metallothionein; Mice; Mice, Knockout; Osteoarthritis; Real-Time Polymerase Chain Reaction

Metallothioneins (MTs) are low-molecular-weight cytosolic proteins, which are thought to participate in metal homeostasis and protection against metal toxicity and oxidative stress. MT synthesis can be induced by a variety of inflammatory mediators and antirheumatic drugs, and high levels of MT have been implicated in resistance of cells to some antirheumatic drugs. We studied the expression and localization of MT in synovial tissue samples from patients with rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis or osteoarthritis (OA) by quantitative immunohistochemistry. Immunostaining for MT was detected in a large number of intimal lining cells in most of the investigated synovial tissue samples (75%). In a smaller proportion of samples (42%), some of the fibroblast-like cells of the subsynovial layer were also MT positive. Immunostaining and double-staining experiments with antibodies against monocyte-, macrophage- and leucocyte-associated antigens suggested that most of the MT-positive cells were intimal fibroblast-like cells and subsynovial fibroblasts. However, there were no statistically significant differences in the intensity of staining for MT between the rheumatic diseases and OA at the single-cell level. Thus, MT is expressed in synovial tissue and may participate in homeostatic and protective functions. The interindividual variability in the expression of MT in synovial tissue may be related to the therapeutic efficacy of the gold compounds and chemotherapeutic antirheumatic drugs sequestered by MT.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Antibodies, Monoclonal; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Antigens, Differentiation, T-Lymphocyte; Antigens, Neoplasm; Arthritis; Arthritis, Psoriatic; Arthritis, Rheumatoid; Child; Female; Humans; Immunohistochemistry; Joint Diseases; Male; Membrane Glycoproteins; Metallothionein; Mice; Middle Aged; Muramidase; Osteoarthritis; Spondylitis, Ankylosing; Synovial Membrane

Metallothionein is a ubiquitous low molecular weight metalloprotein with powerful protective properties against oxygen radical-mediated cytotoxicity associated with inflammatory processes. In rheumatoid arthritis, the inflammatory damage to the synovium appears to be mediated by free radicals released by the high concentration of neutrophils found in the synovial fluid of the inflamed joint. Synovial tissue obtained during routine surgery on rheumatoid and non-rheumatoid joints was subjected to an indirect immunoperoxidase protocol for the immunolocalization of metallothionein using mouse monoclonal anti-metallothionein antibody E9, reactive against the two major isoforms of mammalian metallothionein. A layer of large dendritic-like cells situated subsynovially in the rheumatoid synovium stained very positively for the metalloprotein, both cytoplasmically and in their nuclei. These cells were not found in non-rheumatoid osteoarthritic or in undamaged synovial tissue associated with traumatic joint injury. An attempt was made to investigate their lineage using a series of antibody markers against epithelial cells, endothelial cells, smooth muscle, mesothelial cells, fibroblasts, neutrophils, dermal dendrocytes, macrophages, low and high molecular weight cytokeratin as well as a cell proliferation marker. From our results, it is suggested that these metallothionein-positive cells are probably myofibroblasts similar to the highly motile cells present in granulation tissue. They may originate from perivascular areas of synovium and their movement into the inflamed synovium may reflect the cytoprotective role of metallothionein acting as a free radical scavenger against oxidative damage.

Topics: Antigens, CD; Antigens, Differentiation, Myelomonocytic; Arthritis, Rheumatoid; Biomarkers; Factor XIII; Humans; Immunohistochemistry; Metallothionein; Osteoarthritis; Synovial Membrane

Normal and osteoarthritic (OA) human articular cartilage chondrocytes, released enzymatically in the presence of 0.5% fetal calf serum, display constitutive expression of early response activating protein (AP-1) genes; c-fos, c-jun and jun-B. Among the late AP-1 responsive genes, total metallothionein (MT) and stromelysin mRNAs were expressed at high levels in both normal and OA chondrocytes, while collagenase and hMT-IIA mRNA levels were elevated only in OA individuals. Despite the common AP-1 sequences present in their promoter regions, the three late genes were differentially expressed.

Topics: Aged; Blotting, Northern; Cartilage; DNA-Binding Proteins; Female; Gene Expression; Humans; Male; Metalloendopeptidases; Metallothionein; Osteoarthritis; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun