MAB3318 Sigma-AldrichAnti-TIMP-3 Antibody, a.a. 170-188, clone 136-13H4

Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissue inhibitor of metalloproteinases-3 (TIMP-3) overexpression is protective. MMP-14(hi) TIMP-3(lo) rabbit foam cells are more invasive and more prone to apoptosis than MMP-14(lo) TIMP-3(hi) cells. We investigated the implications of these findings for human atherosclerosis. In vitro generated macrophages and foam-cell macrophages, together with atherosclerotic plaques characterised as unstable or stable, were examined for expression of MMP-14, TIMP-3, and inflammatory markers. Proinflammatory stimuli increased MMP-14 and decreased TIMP-3 mRNA and protein expression in human macrophages. However, conversion to foam-cells with oxidized LDL increased MMP-14 and decreased TIMP-3 protein, independently of inflammatory mediators and partly through posttranscriptional mechanisms. Within atherosclerotic plaques, MMP-14 was prominent in foam-cells with either pro- or anti-inflammatory macrophage markers, whereas TIMP-3 was present in less foamy macrophages and colocalised with CD206. MMP-14 positive macrophages were more abundant whereas TIMP-3 positive macrophages were less abundant in plaques histologically designated as rupture prone. We conclude that foam-cells characterised by high MMP-14 and low TIMP-3 expression are prevalent in rupture-prone atherosclerotic plaques, independent of pro- or anti-inflammatory activation. Therefore reducing MMP-14 activity and increasing that of TIMP-3 could be valid therapeutic approaches to reduce plaque rupture and myocardial infarction.

Migration of the smooth muscle cells (SMCs) to the tunica media in the saphenous vein (SV) transplants is facilitated by matrix metalloproteinases (MMPs). The aim of this study was to identify any associations between expression of MMP-2 or endogenous tissue inhibitors (TIMP-2 and TIMP-3) in the SV segments and late failure of the SV grafts.Two hundred consecutive patients with a mean age of 63.1 ± 8.9 years who underwent primary isolated venous CABG were examined. Patients were retrospectively split into two subgroups, with the SV graft disease (SVGD (+); n = 47) or without it (SVGD (-); n = 153). In the SV segments, immunohistochemical analysis of the expression of the MMP-2, TIMP-2, and -3 was performed.In the SVGD (+) patients, tissue expression of MMP-2 was stronger, whereas that of both TIMPs was weaker than in the SVGD (-) patients. In majority of the SV segments obtained from the SVGD (-) individuals, a balance in MMP and TIMP expressions was found, whereas an upregulation of MMP-2 expression was usually noted in the SVGD (+) subjects.The strong expression of MMP-2 accompanied by reduced immunostaining of both TIMPs is associated with the development of the SV graft disease and unfavorable CABG outcomes.

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.

Tissue inhibitor of metalloproteinase-3 (TIMP3) is a tumor suppressor gene frequently downregulated in prostate cancer. The mechanisms involved in TIMP3 transcriptional repression are not fully understood, but evidence suggests that promoter hypermethylation may not be the predominant epigenetic alteration in prostate cancer. To clarify this issue, we examined the contribution of both CpG site promoter methylation and histone modifications on TIMP3 downregulation. Using publicly available data sets, we confirmed that TIMP3 mRNA expression is decreased in prostate tumors relative to normal glands. Immunohistochemical analysis also showed decreased TIMP3 levels in high-grade primary tumors, but promoter hypermethylation was only detected in 6 of 28 (21%) high-grade specimens. Similarly, in prostate cancer cells, TIMP3 hypermethylation was only observed in DU145 cells. Treatment of DU145 cells with 5-aza-2'-deoxycytidine (5-Aza-CdR) restored TIMP3 expression, and this was significantly amplified by co-treating the cells with the HDAC inhibitor trichostatin A (TSA). Alternatively, in cells that did not exhibit aberrant TIMP3 methylation (LNCaP and PC3), TIMP3 expression could be upregulated by the combination of histone methylation inhibitor 3-Deazaneplanocin A (DZNep) and TSA. This reversal of transcriptional repression was associated with decreased H3K27me3 and increased H3K9ac histone marks at the TIMP3 promoter, as demonstrated by chromatin immunoprecipitation. Collectively, these results indicate that histone modifications can contribute to TIMP3 repression in the absence of promoter hypermethylation, and suggest that the combination of histone modifying agents could restore TIMP3 expression in prostate tumors harboring aberrant histone modifications at the TIMP3 promoter.

Tumor dormancy has important implications for early detection and treatment of cancer. Lack of experimental models and limited clinical accessibility constitute major obstacles to the molecular characterization of dormant tumors. We have developed models in which human tumors remain dormant for a prolonged period of time (greater than 120 days) until they switch to rapid growth and become strongly angiogenic. These angiogenic tumors retain their ability to grow fast once injected in new mice. We hypothesized that dormant tumors undergo a stable genetic reprogramming during their switch to the fast-growing phenotype. Genome-wide transcriptional analysis was done to dissect the molecular mechanisms underlying the switch of dormant breast carcinoma, glioblastoma, osteosarcoma, and liposarcoma tumors. A consensus expression signature distinguishing all four dormant versus switched fast-growing tumors was generated. In alignment with our phenotypic observation, the angiogenesis process was the most significantly affected functional gene category. The switch of dormant tumors was associated with down-regulation of angiogenesis inhibitor thrombospondin and decreased sensitivity of angiogenic tumors to angiostatin. The conversion of dormant tumors to exponentially growing tumors was also correlated with regulation and activation of pathways not hitherto linked to tumor dormancy process, such as endothelial cell-specific molecule-1, 5'-ecto-nucleotidase, tissue inhibitor of metalloproteinase-3, epidermal growth factor receptor, insulin-like growth factor receptor, and phosphatidylinositol 3-kinase signaling. Further, novel dormancy-specific biomarkers such as H2BK and Eph receptor A5 (EphA5) were discovered. EphA5 plasma levels in mice and mRNA levels in tumor specimens of glioma patients correlated with diseases stage. These data will be instrumental in identifying novel early cancer biomarkers and could provide a rationale for development of dormancy-promoting tumor therapy strategies.

Bone lining cells cover > 80% of endosteal surfaces of human cancellous bone. Current research assigns to them a dual role: (1) as a biological membrane regulating exchange of substrates between the bone fluid compartment and the extracellular fluid of bone marrow and (2) as a signaling link between the osteocytic network as mechanical receptor and the osteoclastic cell pool for local induction of bone resorption. Furthermore, a catabolic role has been considered. We therefore examined the presence of matrix-metalloproteinases (MMPs) and their physiological tissue inhibitors (TIMPs) as putative proteolytic elements. Firstly, human cancellous bone from 60 patients was examined by immunofluorescence with antibodies against MMPs and TIMPs. Secondly, we applied laser-assisted microdissection (LMD) to isolate bone lining cells from frozen sections of human trabecular bone. mRNA analysis was performed using a single-cell PCR protocol. Three laser microdissection systems were tested: the new generation of Leica LMD and P.A.L.M. laser pressure catapulting (LPC) were compared to P.A.L.M. laser microdissection and micromanipulation (LMM). In a few pooled cell profiles, mRNA of MMP13, MMP14, TIMP1, and CBFA-1 was clearly detected. By immunofluorescence MMP13 and -14 as well as TIMP1 and -2 were strongly present in lining cells, while MMP2, TIMP3, and TIMP4 showed weak or negative signals. Although the functional impact of these enzymatic components remains open, there is additional evidence for a catabolic function of lining cells. The new diode-laser microdissection with LMD and LPC proved to be especially suitable to gain new insights into the properties of bone lining cells.

We show that endothelial cell (EC)-generated vascular guidance tunnels (ie, matrix spaces created during tube formation) serve as conduits for the recruitment and motility of pericytes along EC ablumenal surfaces to facilitate vessel maturation events, including vascular basement membrane matrix assembly and restriction of EC tube diameter. During quail development, pericyte recruitment along microvascular tubes directly correlates with vascular basement membrane matrix deposition. Pericyte recruitment to EC tubes leads to specific induction of fibronectin and nidogen-1 (ie, matrix-bridging proteins that link together basement membrane components) as well as perlecan and laminin isoforms. Coincident with these events, up-regulation of integrins, alpha(5)beta(1), alpha(3)beta(1), alpha(6)beta(1), and alpha(1)beta(1), which bind fibronectin, nidogens, laminin isoforms, and collagen type IV, occurs in EC-pericyte cocultures, but not EC-only cultures. Integrin-blocking antibodies to these receptors, disruption of fibronectin matrix assembly, and small interfering RNA suppression of pericyte tissue inhibitor of metalloproteinase (TIMP)-3 (a known regulator of vascular tube stabilization) all lead to decreased EC basement membrane, resulting in increased vessel lumen diameter, a key indicator of dysfunctional EC-pericyte interactions. Thus, pericyte recruitment to EC-lined tubes during vasculogenesis is a stimulatory event controlling vascular basement membrane matrix assembly, a fundamental maturation step regulating the transition from vascular morphogenesis to stabilization.

IL-10 is a potent anti-inflammatory molecule, which regulates TNF-alpha at multiple levels. We investigated whether IL-10 also modulated the activity of the TNF-alpha-converting enzyme (TACE). Using an ex vivo fluorogenic assay we observed that LPS rapidly induced TACE activity in monocytes coinciding with release of soluble TNF-alpha. In the presence of IL-10, TNF-alpha production and activation of surface TACE was significantly inhibited. Paradoxically, both LPS with or without IL-10 led to accumulation of surface TACE (albeit catalytically inactive) over a 24 h period. We investigated whether this was mediated through induction of endogenous tissue inhibitor metalloproteinase-3 (TIMP-3). We found that the inhibition of TACE activity at 2 h by IL-10 was not TIMP-3 dependent but that the late accumulation of surface TACE was prevented with TIMP-3 antibodies. Furthermore, induction of endogenous TIMP-3 was observed by western blotting in both LPS- and in LPS with IL-10-treated monocytes from 6 to 8 h of culture. These results indicate that IL-10 further regulates TNF-alpha by modulating TACE activation at early time points and by contributing to the induction of TIMP-3, the natural inhibitor of active TACE, at later time points. These observations add to our understanding of inflammation and the importance of homeostatic regulators of these events.

The tropical spastic paraparesis or human T-cell lymphotropic virus associated myelopathy (TSP/HAM), has been related with an overexpression of matrix metalloproteinases (MMPs), especially MMP-9. Initial studies of reverse zymography with cerebrospinal fluid (CSF) from TSP/HAM patients, and controls showed the presence of TIMPs, endogenous MMP inhibitors. We determined in CSF the levels of TIMPs by immunoanalysis in 25 patients with TSP/HAM, and compared with two groups: controls and patients with acute and subacute inflammatory neurological diseases. We found that TIMP-2, TIMP-3 and TIMP-4 levels were significantly higher than in controls in both TSP/HAM and inflammatory patients, while TIMP-1 was increased only in the inflammatory group. Levels of MMP-3 and MMP-9 from the two groups of patients showed a significant upregulation in CSF. In the CSF of around the 70% of TSP-HAM and inflammatory patients the presence MMP-9 was detected by zymography, but not in controls. MMP-2 was only overexpressed in the acute inflammatory group. The active form of MMP-2 was observed in both groups of patients with a similar high frequency (60%). MMPs overexpressions are independent of the evolution time of the disease in TSP/HAM. The chronic overexpression of these extracelullar matrix proteins detected in CSF of TSP/HAM should be indirectly produced by secreted viral proteins being responsible for the progression of this disease, accounting for the observed differences with acute inflammatory patients. Our results support the existence of an imbalance between MMPs and their endogenous tissue inhibitors, which could be a pathogenic factor in the chronicity of TSP/HAM.

Mutations in tissue inhibitor of metalloproteinases (TIMP)-3 are found in some patients with Sorsby's fundus dystrophy, a retinal degeneration characterized by abnormal deposits in Bruch's membrane and choroidal neovascularization. The purpose of this study was to localize TIMP-3 in the retina/choroid of normal human and animal eyes. Immunolabeling was performed on unfixed and fixed sections of human eyes aged 24 to 85 years and unfixed sections of baboon, chicken, cow, pig, and rat eyes using a monoclonal antibody against a human TIMP-3 synthetic peptide. The antibody produced strong immunolabeling of Bruch's membrane and drusen and weak labeling of retina blood vessels in unfixed human and baboon eyes. Unfixed chicken, cow, pig, and rat tissues showed no reactivity. After antigen retrieval, all fixed human eyes showed specific labeling of Bruch's membrane and drusen, which was strongest in eyes from elderly donors. The results indicate that TIMP-3 is an extracellular matrix component of Bruch's membrane. Thus, abnormal local function of TIMP-3 may lead to the characteristic Bruch's membrane deposits and choroidal neovascularization found in Sorsby's fundus dystrophy. Specific labeling of drusen raises the possibility that altered TIMP-3-mediated matrix remodeling may contribute to age-related degenerative changes in Bruch's membrane.