Matrix metalloproteinase inhibition in atherosclerosis and stroke.

Matrix metalloproteinases (MMPs) are a family of tightly regulated, zinc-dependent proteases that degrade extracellular matrix (ECM), cell surface, and intracellular proteins. Vascular remodeling, whether as a function of normal physiology or as a consequence of a myriad of pathological processes, requires degradation of the ECM. Thus, the expression and activity of many MMPs are up-regulated in numerous conditions affecting the vasculature and often exacerbate vascular dysfunction. A growing body of evidence supports the rationale of using MMP inhibitors for the treatment of cardiovascular diseases, stroke, and chronic vascular dementia. This manuscript will examine promising targets for MMP inhibition in atherosclerosis and stroke, reviewing findings in preclinical animal models and human patient studies. Strategies for MMP inhibition have progressed beyond chelating the catalytic zinc to functional blocking antibodies and peptides that target either the active site or exosites of the enzyme. While the inhibition of MMP activity presents a rational therapeutic avenue, the multiplicity of roles for MMPs and the non-selective nature of MMP inhibitors that cause unintended side-effects hinder full realization of MMP inhibition as therapy for vascular disease. For optimal therapeutic effects to be realized, specific targets for MMP inhibition in these pathologies must first be identified and then attacked by potent and selective agents during the most appropriate timepoint.

Global alteration in gene expression profiles of deciduas from women with idiopathic recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) occurs in ∼5% of women. However, the etiology is still poorly understood. Defects in decidualization of the endometrium during early pregnancy contribute to several pregnancy complications, such as pre-eclampsia and intrauterine growth restriction (IUGR), and are believed to be important in the pathogenesis of idiopathic RPL. We performed microarray analysis to identify gene expression alterations in the deciduas of idiopathic RPL patients. Control patients had one antecedent term delivery, but were undergoing dilation and curettage for current aneuploid miscarriage. Gene expression differences were evaluated using both pathway and gene ontology (GO) analysis. Selected genes were validated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). A total of 155 genes were found to be significantly dysregulated in the deciduas of RPL patients (>2-fold change, P < 0.05), with 22 genes up-regulated and 133 genes down-regulated. GO analysis linked a large percentage of genes to discrete biological functions, including immune response (23%), cell signaling (18%) and cell invasion (17.1%), and pathway analysis revealed consistent changes in both the interleukin 1 (IL-1) and IL-8 pathways. All genes in the IL-8 pathway were up-regulated while genes in the IL-1 pathway were down-regulated. Although both pathways can promote inflammation, IL-1 pathway activity is important for normal implantation. Additionally, genes known to be critical for degradation of the extracellular matrix, including matrix metalloproteinase 26 and serine peptidase inhibitor Kazal-type 1, were also highly up-regulated. In this first microarray approach to decidual gene expression in RPL patients, our data suggest that dysregulation of genes associated with cell invasion and immunity may contribute significantly to idiopathic recurrent miscarriage.

A fresh prospect of extracellular matrix hydrolytic enzymes and their substrates.

Extracellular matrix (ECM) and ECM-hydrolytic enzymes play critical roles in reproduction, development, morphogenesis, wound healing, tissue repair, regeneration, and remodeling. They are also involved in pathological processes such as inflammation, arthritis, cardiovascular diseases, stroke, neurodegeneration, metabolic syndrome, and cancer invasion and metastasis. Other reviews summarized the structure and function of ECM-degrading enzymes in cancer and other diseases. This review will focus on current insights of major protease families and other digestive enzymes that play significant roles in ECM remodeling and ECM-related pathologies. For example, the functions of matrix metalloproteinases in modulating adipogenesis, and their subsequent implications in obese patients, are discussed. Recent discovery and characterization of nineteen members of the human disintegrin-metalloproteinase with thrombospondin motif family have revealed new opportunities of investigating these enzymes in human pathologies, especially in the pathogenesis of osteoarthritis. Although kallikrein-3 was discovered many years ago as prostate specific antigen, the biomarker for detecting human prostate cancer and monitoring its recurrence in patients after surgery, fifteen members of the kallikrein family were reported to participate in physiological and pathological processes. Furthermore, exciting research has been carried out on other important ECM-digestive enzymes, including heparanase, cathepsins, hyaluronidases, and matriptases. Research data have suggested that these enzymes are potential therapeutic targets and biomarkers for cancer, arthritis, obesity, diabetic complications, multiple sclerosis, cardiovascular diseases, cerebral vascular diseases, and many other pathological conditions.

Matrix metalloproteinase-9/gelatinase B is a putative therapeutic target of chronic obstructive pulmonary disease and multiple sclerosis.

Matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes involved in an array of physiological and pathological processes from development, morphogenesis, reproduction, wound healing, and aging to inflammation, angiogenesis, neurological disorders, and cancer cell invasion and metastasis. The imbalance between MMP activity and the inhibitory action of tissue inhibitors of metalloproteinases (TIMPs) are implicated in multiple diseases. Secreted in the body in a latent form, upon activation MMP-9 (gelatinase B) acts on many inflammatory substrates, and thus is suspected of contributing to the progression of cardiovascular disease, rheumatoid arthritis, and the subjects of this review, chronic obstructive pulmonary disease (COPD) and multiple sclerosis (MS). COPD is the fourth most common cause of death in the United States. In COPD, increased expression of MMP-9 by inflammatory cells e.g. neutrophils and macrophages is correlated with a variety of processes that cause lung damage. MMP-9 is also important in cytokine and protease modulation; it degrades the serine protease inhibitor alpha(1)-antitrypsin, which thus may lead to lung destruction. MS affects approximately 400,000 Americans and over a million people worldwide. Upregulation of MMP-9 increases the permeability of the blood brain barrier (BBB), facilitates the infiltration of leukocytes into the central nervous system, and causes myelin sheath degradation and neuronal damage. Early stage clinical trials have shown promising results when MMP-9 is inhibited in MS. These observations lead to the hypothesis that MMP-9 is a potential drug target for both COPD and MS and further development of highly potent and specific MMP-9 inhibitors is warranted.

Inhibitory antibodies against endopeptidase activity of human adamalysin 19.

Human adamalysin 19 (hADAM19)/meltrin beta is a member of the ADAM (a disintegrin and metalloproteinase) family and an active metalloproteinase. It is a new metalloproteinase and disintegrin dendritic cell antigen marker. Adamalysin 19 gene was expressed in normal and transformed tissues and cells such as placenta, brain, heart, leukocytes, and colorectal adenocarcinoma SW480. To develop specific tools to investigate the functions of hADAM19, peptide antigens were rationally selected and specific polyclonal antibodies (pAbs) were developed to modulate hADAM19 activity. Anti-metalloproteinase and anti-disintegrin domain IgG molecules inhibited the alpha-2-macroglobulin cleavage by hADAM19; however, their pre-immune and anti-pro-domain IgG molecules did not. Since anti-disintegrin IgG also neutralized the proteolytic activity, the disintegrin domain may affect the hADAM19 protein folding and/or substrate binding. These pAbs may be used to specifically localize the hADAM19 protein in tissues and cells and elucidate its biological and pathological functions such as processing pro-growth factors.

Stimulation of mammary tumorigenesis by systemic tissue inhibitor of matrix metalloproteinase 4 gene delivery.

Tissue inhibitors of matrix metalloproteinase (TIMPs) are multifunctional proteins with both matrix metalloproteinase (MMP) inhibitory effects and growth-regulatory activity. TIMPs inhibit MMP activity, suggesting a use for cancer gene therapy. However, here we report that systemic administration of human TIMP-4 by electroporation-mediated i.m. injection of naked TIMP-4 DNA stimulates tumorigenesis of human breast cancer cells in nude mice. Consistent with tumor stimulation, TIMP-4 up-regulates Bcl-2 and Bcl-X(L) protein. TIMP-4 also inhibits apoptosis in human breast cancer cells in vitro and mammary tumors in vivo. A synthetic MMP inhibitor BB-94 did not have such antiapoptotic effect. Analysis of TIMP-4 expression in human mammary specimens indicates that TIMP-4 protein is increased in mammary carcinoma cells compared with normal mammary epithelial cells. These data indicate an antiapoptotic activity in breast cancer cells and a tumor-stimulating effect of TIMP-4 when administrated systemically.

Development and characterization of a new polyclonal antibody specifically against tissue inhibitor of metalloproteinases 4 in human breast cancer.

Tissue inhibitors of metalloproteinases (TIMPs) may regulate extracellular matrix turnover and cellular functions by modulating matrix metalloproteinase (MMP) activity and cell proliferation and apoptosis. To investigate the locations and functions of TIMP-4 in human breast cancer, a highly specific polyclonal anti-TIMP-4 peptide antibody (pAb-T4-S61) was developed. The potency and specificity of the purified IgG were characterized by an enzyme-linked immunosorbent assay, immunoblot, and immunohistochemistry. The optimal IgG concentration range was 0.1-10 microg/ml. pAb-T4-S61 did not cross-react with TIMP-1 and TIMP-2 and should not react with TIMP-3 according to the sequence analysis. Parental MDA-MB-435 breast cancer cells were TIMP-4 negative and a TIMP-4 transfected clone, TIMP-4-435-12, produced TIMP-4. Membrane type-1 MMP was detected although TIMP-2 was not found in these cells. Interestingly, the TIMP-4 protein was detected by immunohistochemical staining in infiltrating breast carcinoma cells in tumor tissues. Thus, pAb-T4-S61 is a useful tool to investigate expression patterns and functions of TIMP-4 in cancers.

Expression and enzymatic activity of human disintegrin and metalloproteinase ADAM19/meltrin beta.

The adamalysins are involved in proteolysis, adhesion, fusion, and intracellular signaling. Human ADAM19/adamalysin-19 (A disintegrin and metalloproteinase 19) was identified from primary dendritic cell cDNA libraries. It has a signal sequence, a pro-domain with a "cysteine-switch" residue, a metalloproteinase domain with a zinc-binding site, a disintegrin, a cysteine-rich domain, an epidermal-growth-factor-like domain, a transmembrane domain, and a cytoplasmic domain with putative SH3 ligand binding sites. Its mRNA was expressed in the placenta, heart, bladder, lymph nodes, and leukocytes, colorectal adenocarcinoma SW 480, and other organs/cells. The hADAM19 recombinant protein was expressed in human cells. It formed a complex with and cleaved alpha-2 macroglobulin (alpha2-M). Its proteolytic activity was blocked by 1,10-phenanthroline, EDTA, EGTA, and a synthetic matrix metalloproteinase (MMP) inhibitor and not by the tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2. It did not cleave the MMP substrates tested, e.g., type I collagen and gelatin, casein, and four peptide substrates. Thus, hADAM19 is an active metalloproteinase and may have a specific substrate profile.

New thiol and sulfodiimine metalloproteinase inhibitors and their effect on human microvascular endothelial cell growth.

Matrix metalloproteinases (MMPs, matrixins) are a family of homologous zinc endopeptidases that may play a very important role in many physiological and pathological processes, e.g., the initiation of angiogenesis. Two new matrixin inhibitors were synthesized and characterized. A thiol inhibitor MAG-283 had IC(50) values of 480, 3, 280, 14, 1.1, and 2.3 nM against human interstitial collagenase (MMP-1), gelatinase A (MMP-2), stromelysin (MMP-3), matrilysin (MMP-7), neutrophil collagenase (MMP-8), and gelatinase B (MMP-9), respectively. A sulfodiimine inhibitor YLL-224 had IC(50) values of 180, 63, 4500, 210, 5.9, and 44 nM against MMP-1, -2, -3, -7, -8, and -9, respectively. Human skin microvascular endothelial cells were treated with these two compounds in culture. These inhibitors at very low micromolar concentrations suppressed proliferation of the endothelial cells stimulated by acidic fibroblast growth factor and vascular endothelial growth factor. They also partially blocked cell invasion through type IV collagen. These results suggested a correlation between the anti-metalloenzyme activity and the effects of these inhibitors on the growth and invasion of endothelial cells.

Identification and characterization of human endometase (Matrix metalloproteinase-26) from endometrial tumor.

We report the discovery, cloning, and characterization of a novel human matrix metalloproteinase 26 (MMP-26) (matrixin) gene, endometase, an endometrial tumor-derived metalloproteinase. Among more than three million expressed sequence tags sequenced, the endometase gene was only obtained from human endometrial tumor cDNA library. Endometase mRNA was expressed specifically in human uterus, not in other tissues/cells tested, e.g. testis, heart, brain, lungs, liver, thymus, and melanoma G361. Endometase protein has a signal peptide, a propeptide domain, and a catalytic domain with a unique "cysteine switch" propeptide sequence, PHCGVPDGSD, and a zinc-binding motif, VATHEIGHSLGLQH. Endometase is 43, 41, 41, and 39% identical to human metalloelastase, stromelysin, collagenase-3, and matrilysin, respectively. The zymogen was expressed and isolated from Escherichia coli as inclusion bodies with a molecular mass of 28 kDa. The identity and homogeneity of the recombinant protein was confirmed by protein N-terminal sequencing, silver stain, and immunoblot analyses. The pro-enzyme was partially activated during the folding process. Endometase selectively cleaved type I gelatin and alpha(1)-proteinase inhibitor; however, it did not digest collagens, laminin, elastin, beta-casein, plasminogen, soybean trypsin inhibitor, or Bowman-Birk inhibitor. It hydrolyzed peptide substrates of matrixins and tumor necrosis factor-alpha converting enzyme. Endometase may selectively cleave extracellular matrix proteins, inactivate serpins, and process cytokines.

A novel protease-docking function of integrin at invadopodia.

Invadopodia are membrane extensions of aggressive tumor cells that function in the activation of membrane-bound proteases occurring during tumor cell invasion. We explore a novel and provocative activity of integrins in docking proteases to sites of invasion, termed invadopodia. In the absence of collagen, alpha(3)beta(1) integrin and the gelatinolytic enzyme, seprase, exist as nonassociating membrane proteins. Type I collagen substratum induces the association of alpha(3)beta(1) integrin with seprase as a complex on invadopodia. The results show that alpha(3)beta(1) integrin is a docking protein for seprase to form functional invadopodia. In addition, alpha(5)beta(1) integrin may participate in the adhesion process necessary for invadopodial formation. Thus, alpha(3)beta(1) and alpha(5)beta(1) integrins play major organizational roles in the adhesion and formation of invadopodia, promoting invasive cell behavior.

Structure-function analysis of the ADAM family of disintegrin-like and metalloproteinase-containing proteins (review).

The ADAMs belong to a disintegrin-like and metalloproteinase-containing protein family that are zinc-dependent metalloproteinases. These proteins share all or some of the following domain structure: a signal peptide, a propeptide, a metalloproteinase, a disintegrin, a cysteine-rich, and an epidermal growth factor (EGF)-like domains, a transmembrane region, and a cytoplasmic tail. ADAMs are widely distributed in many organs, tissues, and cells, such as brain, testis, epididymis, ovary, breast, placenta, liver, heart, lung, bone, and muscle. These proteins are capable of four potential functions: proteolysis, adhesion, fusion, and intracellular signaling. Because the number of ADAM genes has grown rapidly and the biological functions of most members are unclear, this review analyzes the protein structures and functions, their activation and processing, their known and potential activities, and their evolutionary relationships. A sequence alignment of human ADAMs is compiled and their homology and physical data are calculated. The conceivable functions of ADAMs in reproduction, development, and diseases are also discussed.

Complex role of matrix metalloproteinases in angiogenesis.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) play a significant role in regulating angiogenesis, the process of new blood vessel formation. Interstitial collagenase (MMP-1), 72 kDa gelatinase A/type IV collagenase (MMP-2), and 92 kDa gelatinase B/type IV collagenase (MMP-9) dissolve extracellular matrix (ECM) and may initiate and promote angiogenesis. TIMP-1, TIMP-2, TIMP-3, and possibly, TIMP-4 inhibit neovascularization. A new paradigm is emerging that matrilysin (MMP-7), MMP-9, and metalloelastase (MMP-12) may block angiogenesis by converting plasminogen to angiostatin, which is one of the most potent angiogenesis antagonists. MMPs and TIMPs play a complex role in regulating angiogenesis. An understanding of the biochemical and cellular pathways and mechanisms of angiogenesis will provide important information to allow the control of angiogenesis, e.g. the stimulation of angiogenesis for coronary collateral circulation formation; while the inhibition for treating arthritis and cancer.

Proteolytic and non-proteolytic activation of human neutrophil progelatinase B.

The activation of human neutrophil progelatinase B (pro-HNG) by a variety of proteolytic and non-proteolytic activators has been investigated. A quantitative comparison of the activation efficiencies of treatments previously reported to activate pro-HNG or the related gelatinase B species produced by other cells demonstrates that stromelysin and trypsin are good activators. HgCl2 is a moderately effective activator, while p-chloromercuribenzoate and NaOCl are poor activators. It is also shown that human matrilysin and human fibroblast-type collagenase can activate pro-HNG by a mechanism that is very similar to that of stromelysin. Initially, these proteinases hydrolyze the Glu40-Met41 bond in the propeptide domain to generate an 88 kDa inactive HNG species. Collagenase also generates a 68 kDa HNG species through hydrolysis of the Ala74-Met75 bond. Ultimately, treatment with either matrilysin, collagenase or trypsin results in the production of a 65 kDa active form of HNG that arises from hydrolysis of the Arg87-Phe88 bond. This is the same active species produced on activation by stromelysin. This cleavage site is downstream of the 'cysteine-switch' residue located at position 80 and releases it, accounting for the permanent activation of the enzyme. These results suggest that matrilysin and collagenase may be physiologically relevant activators of pro-HNG and/or other progelatinase B species. Activation by HgCl2 produces an active 68 kDa enzyme due to autolytic hydrolysis of the Ala74-Met75 bond. This species retains the cysteine switch residue; however, it is shown that it is only active in the continued presence of HgCl2. Removal of the HgCl2 restores latency, indicating that this species is reversibly activated by HgCl2, which functions by complexing the sulfhydryl group of the cysteine switch residue and keeping it dissociated from the active site zinc atom. Thus, in spite of reports to the contrary, the cysteine switch mechanism can account for the latency and activation of pro-HNG.

Comparative sequence specificities of human 72- and 92-kDa gelatinases (type IV collagenases) and PUMP (matrilysin).

The sequence specificities of human 72-kDa fibroblast gelatinase (type IV collagenase), human 92-kDa neutrophil gelatinase (type IV collagenase), and putative metalloproteinase (PUMP or matrilysin) have been examined by measuring the rate of hydrolysis of over 50 synthetic oligopeptides covering the P4 through P4' subsites of the substrate. The peptides investigated in this paper were those employed in our previous study which systematically examined the sequence specificity of human fibroblast and neutrophil collagenases [Netzel-Arnett et al. (1991) J. Biol. Chem. 266, 6747]. The initial rate of hydrolysis of the P1-P1' bond of each peptide has been measured under first-order conditions ([S0] << KM), and kcat/KM values have been calculated from the initial rates. The specificities of these five metalloproteinases are similar, but distinct, with the largest differences occurring at subsites P1, P1', and P3'. The specificities of the two gelatinases are the most similar to each other. They tolerate only small amino acids such as Gly and Ala in subsite P1. In contrast, larger residues such as Met, Pro, Gln, and Glu are also accommodated well by PUMP. All five enzymes prefer hydrophobic, aliphatic residues in subsite P1'. PUMP exhibits a stronger preference for Leu in this subsite than is shown by the other enzymes. The P3' subsite specificities of the gelatinases and collagenases are very similar but different from those of PUMP which particularly prefers Met in this position. The specificity data from this study allow the design of optimized substrates and selective inhibitors for these metalloproteinases.

Soluble laminin and arginine-glycine-aspartic acid containing peptides differentially regulate type IV collagenase messenger RNA, activation, and localization in testicular cell culture.

Rat testicular cells in culture produce several metalloproteinases including type IV collagenases (Sang et al. Biol Reprod 1990; 43:946-955, 956-964). We have now investigated the regulation of testicular cell type IV collagenase and other metalloproteinases in vitro. Soluble laminin stimulated Sertoli cell type IV collagenase mRNA levels. However, three peptides corresponding to different domains of the laminin molecule (CSRAKQAASIKVASADR, FALRGDNP, CLQDGDVRV) did not influence type IV collagenase mRNA levels. Zymographic analysis of medium collected from these cultures revealed that neither soluble laminin nor any of the peptides influenced 72-kDa type IV collagenase protein levels. However, peptide FALRGDNP resulted in both, a selective increase in two higher molecular-weight metalloproteinases (83 kDa and 110 kDa and in an activation of the 72-kDa rat type IV collagenase. Interleukin-1, phorbol ester, testosterone, and FSH did not affect collagenase activation. Immunocytochemical studies demonstrated that the addition of soluble laminin resulted in a redistribution of type IV collagenase from intracellular vesicles to the cell-substrate region beneath the cells. Peptide FALRGDNP induced a change from a vesicular to peripheral plasma membrane type of staining pattern. Zymography of plasma membrane preparations demonstrated triton-soluble gelatinases of 76 kDa, 83 kDa, and 110 kDa and a triton-insoluble gelatinase of 225 kDa. These results indicate that testicular cell type IV collagenase mRNA levels, enzyme activation, and distribution are influenced by laminin and RGD-containing peptides.

Secreted metalloproteinases in testicular cell culture.

It is well known that cultured Sertoli cells secrete plasminogen activators (Lacroix et al., Mol Cell Endocrinol 1977; 9:227-236; Hettle et al., Biol Reprod 1986; 34:895-904). We now show that testicular cells in culture also secrete gelatinolytic metalloproteinases. Gelatin zymographic analysis of concentrated culture medium proteins reveals that Sertoli cells secrete gelatinases of 185 kDa, 110 kDa, 83 kDa, 76 kDa, and 72 kDa in addition to plasminogen activators (PAs). Gelatinase 185 kDa is induced by FSH. Media from Sertoli (epithelial)/peritubular (mesenchymal) cell cocultures contain the Sertoli cell gelatinases and one FSH-stimulated gelatinase of 50 kDa, indicating that gelatinase 50 kDa is regulated by both FSH and cell-cell interactions. A 50-kDa fibronectinolytic activity is also present in the coculture medium from cells grown in the presence of FSH. Casein zymography demonstrates a prominent 30-kDa protease only in media from cocultures. Peritubular cells secrete urokinase-type plasminogen activator (u-PA) and exhibit slight degrading activity at 86 kDa and 74 kDa. The gelatinases are most active in the pH range 7.3-8.5 and are completely or partially inhibited by metal ion chelators indicating that they are metalloproteinases. Our data demonstrate that testicular cells in culture secrete several gelatinases in addition to PAs, and that FSH and coculture conditions regulate some of these secreted proteases. We suggest that the highly regulated secretion of these proteases may well be of physiological importance during testicular development and spermatogenesis.

Identification of type IV collagenase in rat testicular cell culture: influence of peritubular-Sertoli cell interactions.

In the testis, interactions between peritubular cells (mesenchyme) and Sertoli cells (epithelium), together with proteolytic remodeling of the extracellular matrix, may play a central role in testicular development, morphogenesis, and spermatogenesis. In this study we demonstrate that a metalloproteinase of 72 kDa present in rat Sertoli cell and Sertoli-peritubular cell coculture medium is activated by p-aminophenylmercuric acetate (p-APMA) to a lower molecular mass form, indicating that it is likely to be a latent collagenase. Immunoblots using antibodies to three different domains of type IV collagenase show that the 72-kDa protease and a 76-kDa protease are type IV pro-collagenases. Sertoli cells cultured alone produce basal levels of type IV collagenase that can be immunolocalized in the cytoplasm of cultured cells. Peritubular cells cultured alone produce much less type IV collagenase. However, Sertoli and peritubular cells in coculture do produce type IV pro-collagenase, and in cultures consisting predominantly of peritubular cells, the activated form of type IV collagenase was detected by both zymography and immunoblotting. Cells growing during the transitional phase (from cell attachment to confluence) secrete more metalloproteinases than during the confluent phase. In contrast, plasminogen activator levels are unaffected by time in culture. These results show that rat testicular cells in culture produce and secrete type IV collagenase, and that the secretion and activation of this enzyme and other metalloproteases is regulated by the ratio of mesenchymal cells to epithelial cells and time in culture.