Characterization of gelatinase from pig polymorphonuclear leucocytes. A metalloproteinase resembling tumour type IV collagenase

Discovery of potent and specific inhibitors targeting the active site of MMP-9 from the engineered SPINK2 library

Matrix metalloproteinases (MMPs) contribute to many physiological and pathological phenomena via the proteolysis of extracellular matrix components. Specific blocking of the active site of each MMP sheds light on its particular role. However, it remains difficult to acquire an active-site inhibitor with high specificity for only the target MMP due to the highly conserved structure around the active site of MMPs. Recently, we reported that potent and specific inhibitors of serine proteases were obtained from our proprietary engineered serine protease inhibitor Kazal type 2 (SPINK2) library. In this research, using this library, we succeeded in obtaining potent and specific MMP-9 inhibitors. The obtained inhibitors bound to the active site of MMP-9 and inhibited MMP-9 with low nanomolar Ki values. The inhibitors did not cross-react with other MMPs that we tested. Further analysis using MMP-9 mutants demonstrated that the inhibitors recognize not only the residues around the conserved active site of MMP-9 but also different and unique residues in exosites that are distant from each other. This unique recognition manner, which can be achieved by the large interface provided by engineered SPINK2, may contribute to the generation of specific active-site inhibitors of MMPs.

Dynamic analysis of m6A methylation spectroscopy during progression and reversal of hepatic fibrosis

Aim: To dynamically analyze the differential m6A methylation during the progression and reversal of hepatic fibrosis. Materials & methods: We induced hepatic fibrosis in C57/BL6 mice by intraperitoneal injection of CCl4. The reversal model of hepatic fibrosis was established by stopping drug after continuous injection of CCl4. Dynamic m6A methylation was evaluated using MeRIP-Seq in the progression and reversal of hepatic fibrosis at different stages. Result: During the hepatic fibrosis, differential m6A methylation was mainly enriched in processes associated with oxidative stress and cytochrome metabolism, while differential m6A methylation was mainly enriched in processes associated with immune response and apoptosis in the hepatic fibrosis reversal. Conclusion: m6A methylation plays an important role in the progression and reversal of hepatic fibrosis.

What Is the Evolutionary Fingerprint in Neutrophil Granulocytes?

Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.

Re-epithelialization and immune cell behaviour in an ex vivo human skin model

A large body of literature is available on wound healing in humans. Nonetheless, a standardized ex vivo wound model without disruption of the dermal compartment has not been put forward with compelling justification. Here, we present a novel wound model based on application of negative pressure and its effects for epidermal regeneration and immune cell behaviour. Importantly, the basement membrane remained intact after blister roof removal and keratinocytes were absent in the wounded area. Upon six days of culture, the wound was covered with one to three-cell thick K14⁺Ki67⁺ keratinocyte layers, indicating that proliferation and migration were involved in wound closure. After eight to twelve days, a multi-layered epidermis was formed expressing epidermal differentiation markers (K10, filaggrin, DSG-1, CDSN). Investigations about immune cell-specific manners revealed more T cells in the blister roof epidermis compared to normal epidermis. We identified several cell populations in blister roof epidermis and suction blister fluid that are absent in normal epidermis which correlated with their decrease in the dermis, indicating a dermal efflux upon negative pressure. Together, our model recapitulates the main features of epithelial wound regeneration, and can be applied for testing wound healing therapies and investigating underlying mechanisms.

Re-epithelialization and immune cell behaviour in an ex vivo human skin model

A large body of literature is available on wound healing in humans. Nonetheless, a standardized ex vivo wound model without disruption of the dermal compartment has not been put forward with compelling justification. Here, we present a novel wound model based on application of negative pressure and its effects for epidermal regeneration and immune cell behaviour. Importantly, the basement membrane remained intact after blister roof removal and keratinocytes were absent in the wounded area. Upon six days of culture, the wound was covered with one to three-cell thick K14⁺Ki67⁺ keratinocyte layers, indicating that proliferation and migration were involved in wound closure. After eight to twelve days, a multi-layered epidermis was formed expressing epidermal differentiation markers (K10, filaggrin, DSG-1, CDSN). Investigations about immune cell-specific manners revealed more T cells in the blister roof epidermis compared to normal epidermis. We identified several cell populations in blister roof epidermis and suction blister fluid that are absent in normal epidermis which correlated with their decrease in the dermis, indicating a dermal efflux upon negative pressure. Together, our model recapitulates the main features of epithelial wound regeneration, and can be applied for testing wound healing therapies and investigating underlying mechanisms.

Matrix Metalloproteinases in Renal Diseases: A Critical Appraisal

Matrix metalloproteinases (MMPs) are endopeptidases within the metzincin protein family that not only cleave extracellular matrix (ECM) components, but also process the non-ECM molecules, including various growth factors and their binding proteins. MMPs participate in cell to ECM interactions, and MMPs are known to be involved in cell proliferation mechanisms and most probably apoptosis. These proteinases are grouped into six classes: collagenases, gelatinases, stromelysins, matrilysins, membrane type MMPs, and other MMPs. Various mechanisms regulate the activity of MMPs, inhibition by tissue inhibitors of metalloproteinases being the most important. In the kidney, intrinsic glomerular cells and tubular epithelial cells synthesize several MMPs. The measurement of circulating MMPs can provide valuable information in patients with kidney diseases. They play an important role in many renal diseases, both acute and chronic. This review attempts to summarize the current knowledge of MMPs in the kidney and discusses recent data from patient and animal studies with reference to specific diseases. A better understanding of the MMPs' role in renal remodeling may open the way to new interventions favoring deleterious renal changes in a number of kidney diseases.

Morphological characterization of para- and proinflammatory neutrophil phenotypes using transmission electron microscopy

BACKGROUND AND OBJECTIVE

Bacterial challenge is constant in the oral cavity. To contain the commensal biofilm, partly activated neutrophils are continuously recruited as part of a normal physiologic process, without exposing the host to the harmful effect of a fully active neutrophil response. This intermediate immune state has been termed para-inflammation, as opposed to the fully activated proinflammatory state in oral disease. Directly visualizing these cells and their components via transmission electron microscopy (TEM) enhances our understanding of neutrophil activation state differences in oral health and disease, as obtained from molecular studies. The aim of this study was to describe the morphology of the para-inflammatory phenotype displayed by oral neutrophils in health, and compare it to the morphology of the naïve blood neutrophil, and the proinflammatory oral neutrophils in chronic periodontitis. This morphology was characterized by differences in granule content, phagosome content and cytoplasm and nuclear changes. We also examined the morphological changes induced in naïve neutrophils, which were stimulated in vitro by bacteria, and in oral neutrophils in full tissue samples in vivo.

MATERIAL AND METHODS

Neutrophils were isolated from blood and saliva samples of patients with chronic periodontitis and healthy individuals. The cells were viewed under TEM and analyzed in imaging software examining granularity, cytoplasm density, euchromatin amount in the nucleus and phagosome content. A separate cohort of blood neutrophils was incubated with Streptococcus oralis and analyzed under TEM in the same manner. Gingival tissue samples were obtained from patients with chronic periodontitis and viewed under TEM, with the neutrophils present analyzed in the same manner.

RESULTS

The proinflammatory cells showed less granulation, lighter cytoplasm and higher amount of nuclear euchromatin. These changes were accentuated in the proinflammatory oral chronic periodontitis neutrophils compared to the para-inflammatory oral health neutrophils. The oral chronic periodontitis neutrophils also contained more phagosomes and had more phagosomes containing undigested bacteria. These changes were partially reproduced in the naïve blood cells after exposing them to S. oralis. The neutrophils in the gingival tissues displayed naïve morphology when viewed in the blood vessels and gradually showed proinflammatory morphological changes as they traveled through the connective tissue into the epithelium.

CONCLUSION

Oral neutrophils display morphological changes consistent with partial or full activation, corresponding to their para- or proinflammatory states. These changes can also be induced in naïve cells by incubating them with commensal bacteria. Neutrophils change their morphology towards an activated state as they travel through the gingival tissue.

Matrix metalloproteinase and tissue inhibitor of metalloproteinase responses to muscle damage after eccentric exercise

High-intensity eccentric exercise is known to induce muscle damage leading to inflammatory responses and extracellular matrix (ECM) degradation. These degradation processes involve enzymes such as matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs). MMPs are calcium and zinc-dependent proteolytic enzymes that play a role in ECM degradation and recruitment of inflammatory and myogenic cells into the damaged site. In contrast, TIMPs inhibit MMP-induced ECM degradation to maintain normal homeostasis in ECM. Recently, several studies have examined the process of muscle remodeling and the roles of ECM, MMPs, and TIMPs in exercise-induced muscle damage. However, the results of these studies are not inconsistent. In the present mini-review, we will discuss the responses of MMP and TIMP to eccentric exercise based on the literature review.

Regulation of MT1-MMP/MMP-2/TIMP-2 axis in human placenta

Matrix metalloproteinases (MMPs) and specific endogenous tissue inhibitors of metalloproteinases (TIMPs) mediate rupture of the fetal membranes in both physiological and pathological conditions. MMPs and TIMPs are subject to regulation by DNA methylation in human malignancies and pre-eclampsia. To determine if membrane type 1 MMP (MT1-MMP), MMP2, and TIMP2 are regulated by DNA methylation in human placentas, we employed an in vitro model where human placental tissues were collected at term gestation and cultured with methylation inhibiting agent 5-AZA-2′-deoxycytidine (AZA) and lipopolysaccharide. The results suggest that DNA methylation is not directly involved in the regulation of MT1-MMP in placental tissue; however, remodeling of chromatin by a pharmacologic agent such as AZA potentiates an infection-related increase in MT1-MMP. MT1-MMP is a powerful activator of MMP2 and this action, coupled with either no change or a decrease in TIMP2 concentrations, favors a gelatinolytic state leading to extracellular matrix degradation, which could predispose fetal membranes to rupture prematurely during inflammation.

Acetyl-L-Carnitine Prevents Methamphetamine-Induced Structural Damage on Endothelial Cells via ILK-Related MMP-9 Activity

Methamphetamine (METH) is a potent psychostimulant highly used worldwide. Recent studies evidenced the involvement of METH in the breakdown of the blood-brain-barrier (BBB) integrity leading to compromised function. The involvement of the matrix metalloproteinases (MMPs) in the degradation of the neurovascular matrix components and tight junctions (TJs) is one of the most recent findings in METH-induced toxicity. As BBB dysfunction is a pathological feature of many neurological conditions, unveiling new protective agents in this field is of major relevance. Acetyl-L-carnitine (ALC) has been described to protect the BBB function in different paradigms, but the mechanisms underling its action remain mostly unknown. Here, the immortalized bEnd.3 cell line was used to evaluate the neuroprotective features of ALC in METH-induced damage. Cells were exposed to ranging concentrations of METH, and the protective effect of ALC 1 mM was assessed 24 h after treatment. F-actin rearrangement, TJ expression and distribution, and MMPs activity were evaluated. Integrin-linked kinase (ILK) knockdown cells were used to assess role of ALC in ILK mediated METH-triggered MMPs' activity. Our results show that METH led to disruption of the actin filaments concomitant with claudin-5 translocation to the cytoplasm. These events were mediated by MMP-9 activation in association with ILK overexpression. Pretreatment with ALC prevented METH-induced activation of MMP-9, preserving claudin-5 location and the structural arrangement of the actin filaments. The present results support the potential of ALC in preserving BBB integrity, highlighting ILK as a new target for the ALC therapeutic use.

Meta-analysis of MMP2, MMP3, and MMP9 promoter polymorphisms and head and neck cancer risk

Background

The 1306 C>T, 1171 5A>6A, and 1562C>T polymorphisms of matrix metalloproteinase (MMP) 2, MMP3, and MMP9 genes, respectively, have been found to be functional and may contribute to head and neck carcinogenesis. However, the results of case-control studies examining associations between MMP polymorphisms and head and neck cancer (HNC) risk remain inconclusive. Therefore, we performed a meta-analysis to further evaluate the role of these polymorphisms in HNC development.

Methods

We searched PubMed, ISI Web of Knowledge, MEDLINE, Embase, and Google Scholar to identify all published case-control studies of MMP2-1306 C>T, MMP3-1171 5A>6A, and MMP9-1562 C>T polymorphisms and HNC risk in the meta-analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association between these polymorphisms and HNC risk.

Results

Thirteen studies were included in this meta-analysis. For MMP2-1306 C>T polymorphism, significant associations were observed under three genetic models both in overall comparison and in a hospital-based subgroup, and in oral cavity cancer and nasopharyngeal cancer under dominant model as well. For MMP3-1171 5A>6A and MMP9-1562 C>T polymorphisms, no association was found in overall comparison; however, in subgroup analyses based on ethnicity and tumor site, significant associations were detected between the MMP3-1171 5A>6A polymorphism and HNC risk in a European population and pharyngeal/laryngeal cancer under two genetic contrasts.

Conclusion

This meta-analysis suggests that the MMP2-1306 C>T polymorphism is associated with HNC risk, as is the MMP3-1171 5A>6A polymorphism specifically in some subgroups. Further studies with larger sample sizes are warranted.

MMP 9 Gene Promoter Polymorphism in Gastric Cancer

Matrix metalloproteinase-9 (gelatinase B) plays a key role in cancer invasion and metastasis by degrading the extracellular matrix and basement membrane barriers. A cytosine (C) > thymidine (T) single nucleotide polymorphism (SNP) at position -1562 in the MMP-9 promoter is reported to influence the expression of the gene. Genotyping of MMP-9 -1562 C→T promoter polymorphism in 140 gastric cancer patients and 132 healthy control subjects was carried out in order to evaluate its association with progression and development of gastric cancer. The SNP was genotyped by tetra-primer amplification refractory mutation system-polymerase chain reaction followed by agarose gel electrophoresis. Statistical methods were adopted to test for the significance of the results. Risk factor profile of the patients revealed age above 50 years, smoking, alcoholism as the factors associated with the disease. The distribution of genotype frequencies in gastric cancer patients were 28.7 % of CC, 45.5 % of CT and 25.7 % of TT, whereas in control subjects 31.8 % of CC, 53.03 % of CT and 15.15 % of TT, respectively. The allelic frequencies were 51.51 % of C and 48.48 % of T in patient group and 58.33 % of C and 41.66 % of T in controls respectively. The present study shows the possible association of epidemiological risk factors with gastric cancer. There is an increased frequency of T allele in the disease compared to control subjects. However, there is no association of the MMP-9 -1562 C→T promoter polymorphism in the development of gastric cancer.

Recombinant viral protein promotes apoptosis and suppresses invasion of ovarian adenocarcinoma cells by targeting α5β1 integrin to down-regulate Akt and MMP-2

BACKGROUND AND PURPOSE

As prognosis for patients with metastatic ovarian cancer is generally poor, advances in treatment are needed. Here, we studied the mechanism of action of a recombinant viral capsid protein (rVP1) and explored its effect against ovarian tumour growth and metastasis in vivo.

EXPERIMENTAL APPROACH

The human ovarian cancer cell line SKOV3 and BALB/cAnN-Foxn1 female nude mice were used. Effects of rVP1 on the viability, invasive ability, matrix metalloproteinase (MMP)-2 activity and cancer cell proliferation and metastasis were determined by cell proliferation assay, Matrigel invasion assay, gelatin zymographic analysis, as well as bioluminescence imaging and immunohistological analysis in xenograft mouse models respectively. Levels of total and phosphorylated focal adhesion kinase (FAK), PKB/Akt, phosphatase and tensin homologue (PTEN) and glycogen synthase kinase-3β (GSK-3β) were detected by Western blotting.

KEY RESULTS

rVP1 promoted apoptosis and decreased invasion of human ovarian cancer cells. This effect of rVP1 was accompanied by activation of PTEN and GSK-3β as well as down-regulation of FAK, Akt and MMP-2. Anti-integrin antibodies or overexpression of constitutively active Akt reversed the cellular effects of rVP1. Orthotopic and intraperitoneal xenograft mouse models demonstrated that rVP1 attenuated survival and metastasis of human ovarian cancer SKOV3 cell line in vivo through selective regulation of Akt and GSK-3β activity as shown by bioluminescence imaging of mice and immunohistochemical analysis.

CONCLUSION AND IMPLICATIONS

These results indicate that negative regulation of Akt signalling and MMP-2 by rVP1 may have the potential to suppress ovarian tumour growth and metastasis in vivo.

Fibronectin induces matrix metalloproteinase-9 (MMP-9) in human laryngeal carcinoma cells by involving multiple signaling pathways

Cell adhesion to extracellular matrix initiates intracellular signaling cascade regulated by integrin family of receptors. Evidences show that cultured cells in presence of extracellular matrix adhesion molecule Fibronectin (FN) stimulates secretion of matrix metalloproteinases (MMPs), facilitating cancer cell invasion. Amongst all MMPs, MMP-9 is often reported to play crucial role in tumor cell growth and metastasis. The present study aims at examining the effects of FN on MMP-9 in laryngeal carcinoma cell line, HEp-2, and understand the molecular mechanism(s) involved. The study reports that FN induces the gelatinolytic activity, mRNA and protein expression of MMP-9 in HEp-2 cells. This effect appears to be mediated mainly by integrin receptor α5β1, since, the blockade of α5 abrogated the FN-mediated stimulatory response on MMP-9. siRNA and inhibitor studies suggested involvement of Focal adhesion kinase (FAK), Phosphatidyl-inositol-3-kinase (PI-3K), Extracellular regulated kinase (ERK) and nuclear factor-kappaB (NFκB) in FN-mediated MMP-9 induction. Immunocytochemical analysis demonstrated the nuclear localization of ERK, PI-3K and NFκB; immunoblot showed enhanced expression of p-FAK, p-PI-3K, p-ERK and nuclear-NF-κB and indicated involvement of ILK in the FN-mediated response. FN-induced transactivation of MMP-9 gene by enhanced DNA binding activity of transcription factors NFκB, Activator protein-1 (AP-1) and Specificity protein-1 (Sp1) to the MMP-9 promoter. Thus, this study suggests that extracellular matrix protein FN induces MMP-9 in HEp-2 cells mainly by involving integrin receptor α5β1 and involves activation of multiple signaling pathways which independently or in "cross-talk" to each other finally leads to the transactivation of the MMP-9 gene.

Genetic polymorphisms of matrix metalloproteinases and their inhibitors in potentially malignant and malignant lesions of the head and neck

Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases that are capable of cleaving all extra cellular matrix (ECM) substrates. Degradation of matrix is a key event in progression, invasion and metastasis of potentially malignant and malignant lesions of the head and neck. It might have an important polymorphic association at the promoter regions of several MMPs such as MMP-1 (-1607 1G/2G), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) and TIMP-2 (-418 G/C or C/C). Tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring inhibitors of MMPs, which inhibit the activity of MMPs and control the breakdown of ECM. Currently, many MMP inhibitors (MMPIs) are under development for treating different malignancies. Useful markers associated with molecular aggressiveness might have a role in prognostication of malignancies and to better recognize patient groups that need more antagonistic treatment options. Furthermore, the introduction of novel prognostic markers may also promote exclusively new treatment possibilities, and there is an obvious need to identify markers that could be used as selection criteria for novel therapies. The objective of this review is to discuss the molecular functions and polymorphic association of MMPs and TIMPs and the possible therapeutic aspects of these proteinases in potentially malignant and malignant head and neck lesions. So far, no promising drug target therapy has been developed for MMPs in the lesions of this region. In conclusion, further research is required for the development of their potential diagnostic and therapeutic possibilities.

Activation of AP-1 and Increased Synthesis of MMP-9 in the Rabbit Retina Induced by Lipid Hydroperoxide

PURPOSE

We identified the temporal expression of activator protein-1 (AP-1) and matrix metalloproteinases (MMPs) after linoleic acid hydroperoxide (LHP) induction of retinal neovascularization.

METHODS

After injection of LHP into the vitreous of rabbits, samples were collected for AP-1 binding activity and mRNA for MMP-9 and MMPs activity. AP-1 binding activity was measured by electrophoretic mobility shift assay. MMP-9 activity was measured by zymography and mRNA by quantitative RT-PCR.

RESULTS

AP-1 binding activity was increased at 1-3 hr. MMP-9 mRNA levels were increased at 3 hr in the neural retina and by 12 hr in the retinal pigment epithelium (RPE) layer. MMP-9 proteolytic activity was elevated within the neural retina and within the vitreous and in the RPE-interphotoreceptor matrix (IPM) at 12 hr and peaked at 24 hr or 4 days.

CONCLUSIONS

LHP increases the transcription factor AP-1 which in turn may regulate retinal MMP-9 synthesis during neovascularization.

Expression of matrix metalloproteinase 2 and 9 in experimentally wounded canine corneas and spontaneous chronic corneal epithelial defects

PURPOSE

To determine matrix metalloproteinase (MMP) 2 and MMP 9 expression in acute and chronic experimentally wounded canine corneas and keratectomy samples from canine patients with spontaneous chronic corneal epithelial defects (SCCEDs).

METHODS

Mechanical debridement was performed unilaterally in 25 healthy dogs for the acute wound study. Twenty-four hours (n = 8), 48 hours (n = 5), 72 hours (n = 3), or 1 week (n = 9) after wounding, the dogs were euthanized. Debridement was performed once weekly for 8 weeks for the chronic study (n = 8). Therapeutic superficial keratectomies (n = 16) were performed on SCCED patients. Gelatin zymography and immunohistochemistry were performed.

RESULTS

Acute wounds showed upregulation of MMP 9 at all time points. At 7 days after wounding, values diminished markedly but remained elevated above those of unwounded controls. SCCED and chronic wound samples showed a significant increase in MMP 9 compared with controls but were less than that of acute wounds. There was no significant difference between chronic wounds versus SCCED samples. Fellow control eyes showed significant upregulation of MMP 9 in tandem with wounded eyes. There was no significant difference in values for MMP 2 in wounded corneas or SCCED compared with those of controls. Immunhistochemistry localized MMP 9 to predominantly the epithelium with some staining of keratinocytes and stroma.

CONCLUSIONS

The dog exhibits similar MMP expression during corneal wound healing to that of other species. The lack of significant difference in MMP expression between SCCED and chronic wounds suggest that MMP 2 and 9 are not involved in the pathophysiology of SCCED and are more likely altered secondary to a chronic epithelial defect.

Matrix metalloproteinase (MMP)-2 and MMP-9 activity in the canine uterus before and during placentation

The aim of the present study was to demonstrate the presence and localization of MMP-2 and -9 by means of RT-PCR and immunohistochemistry (IHC) within the canine uterus from the pre-implantation stage until mid-gestation and to determine MMP-2 and -9 activities by means of zymography. For this purpose, samples of the uterus and salpinx from bitches were obtained after ovariohysterectomy. Pre-implantation stages (5-12 days after mating, n = 11) were determined by verifying embryos after flushing the uterus. Further groups were determined as implantation (15-19 days after mating, n = 9), post-implantation (20-30 days after mating, n = 9) and placental stages (30-45 days after mating, n = 3). A non-pregnant group (17-30 days after mating, n = 4) served as control. MMP-2 and -9 positive cells were detected in all specimens from pregnant and nonpregnant bitches, however, with different distributions. MMP-2 was present in endothelium and smooth muscles of blood vessels and the myometrium of pregnant and nonpregnant bitches, additionally in the surface epithelium of the oviduct. The latter also stained positive for MMP-9. During placentation, MMP-2 was detected mainly in fetal blood vessels and trophoblastic cells. Higher MMP-2 activity was observed in the endometrium and myometrium of all pregnant groups compared with the nonpregnant group (p < 0.05). The pregnant groups did not differ significantly from each other (p > 0.05). MMP-9 was present in blood vessels, smooth muscle cells and epithelia, such as maternal surface epithelial cells, uterine crypts and glands. During placentation, the deep uterine glands and the epithelium of the glandular chambers were immunoreactive to MMP-9. Highest MMP-9 activities were reached in the endometrium of the pre-implantation group (23.2% of total MMP-9) and placental parts (33.3%).

Matrix metalloproteinases and their inhibitors in the chamber angle of normal eyes and patients with primary open-angle glaucoma and exfoliation glaucoma

BACKGROUND

In glaucoma, extensive pathological changes occur in the trabecular meshwork (TM) and juxtacanalicular tissue of the chamber angle. Aqueous humor drainage is disturbed due to the accumulation of extracellular matrix (ECM) material in the outflow system. Matrix metalloproteinases (MMPs) remodel ECM material and, thus, they may have a role in regulating outflow facility and intraocular pressure (IOP). This study examined the expression of MMPs and tissue inhibitors of MMPs (TIMPs) in the chamber angle of normal eyes and in primary open-angle glaucoma (POAG) and in exfoliation glaucoma (ExG).

METHODS

TM tissues were isolated from healthy donor eyes for corneal transplantation. Specimens of the inner wall of Schlemm's canal and the juxtacanalicular tissue were collected from patients with POAG or ExG during deep sclerectomy operation. Monoclonal antibodies against MMPs (MMP-1, -2, -3, and -9) and antibodies against TIMPs (TIMP-1, -2, and -3) were used for immunohistochemical staining.

RESULTS

Immunoreactivity for MMP-2, TIMP-2, or TIMP-3 was observed in human normal TM and in the inner wall of Schlemm's canal. In general, immunoreactions for all of the tested MMPs were more intense in POAG samples than in ExG samples or in the control group. The only exception was the MMP-2 level, which was the highest in the control group. The staining intensity of MMP-1 or MMP-3 was significantly higher in POAG when compared to ExG. TIMP-1 was significantly increased in POAG compared with ExG and there were no marked differences in the levels of TIMP-2 or TIMP-3 between POAG and ExG. The ratios of MMP-1/TIMP-1 and MMP(1+2+3+9) and TIMP(1+2+3) were significantly higher in samples from POAG compared to those of ExG.

CONCLUSIONS

Our results reveal an expression imbalance between MMPs and their endogenous tissue inhibitors in tissue samples from patients with POAG and ExG. Differences in immunohistochemical reactions reflect discrete local pathogenic mechanisms involved in POAG and ExG. With respect to the proposed role of MMPs in the remodeling of ECM material, this may point to a weaker reactivity to the accumulation of ECM material in TM in ExG than POAG eyes.

Carboxy derivatized glucosamine is a potent inhibitor of matrix metalloproteinase-9 in HT1080 cells

Experimental evidences have confirmed that matrix metalloproteinases (MMPs) play a fundamental role in a wide variety of pathologic conditions and recent advances in medicinal chemistry approach to the design of MMP inhibitors with desired structural and functional properties. Among MMPs, MMP-9 has demonstrated to play a major role in the establishment of metastases and it is substantially increased in the majority of malignant tumors. Inhibition of MMP-9 is thought to have a therapeutic benefit to cancer. Results of this study present a novel synthetic MMP-9 inhibitor that downregulates MMP-9 expression level in HT1080, human fibrosarcoma cells.

Protease analysis by neoepitope approach reveals the activation of MMP-9 is achieved proteolytically in a test tissue cartilage model involved in bone formation

A principle of regulation of matrix metalloproteinase (MMP) activity has been introduced as the cysteine-switch mechanism of activation (Springman et al. 1990). According to this mechanism, a critical Cys residue found in the auto-inhibitory propeptide domain of latent proenzyme is important to determine whether or not activation is turned on or off. The mechanism further allows for multiple modes of activation. To determine whether or not activation is accomplished proteolytically within a rat test cartilage model, protease analysis by the neoepitope approach, which relies upon a set of antibodies, was applied. One is used to identify the MMP-9 proenzyme bearing the critical cysteine residue, the other to identify any enzyme present bearing a new NH2-terminus 89FQTFD. This is indicative of MMP-9 lacking the cysteine switch. The antibody set has been applied to frozen tissue sections and analyzed by light and electron microscopic methods. Results reveal that activation of the MMP-9 protease involves limited proteolysis resulting in propeptide domain release. Here we report the observed changes of protease form to indigenous cells and extracellular matrix, thereby making it possible to uncover the features of MMP-9 activation within a specified set of tissue circumstances where a cartilage model is transformed into definitive bone. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Increased ADAMTS-13 proteolytic activity in rat hepatic stellate cells upon activation in vitro and in vivo

INTRODUCTION

ADAMTS-13 is a member of A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats (ADAMTS) family, primarily synthesized in hepatic stellate cells (HSCs), one of the major cell types transdifferentiating into myofibroblasts during liver fibrosis. However, the association between ADAMTS-13 expression and HSC activation or liver fibrosis is not known.

METHODS

In this study, we determined the ADAMTS-13 mRNA, protein, and activity in isolated primary HSCs upon activation on a plastic dish and in liver after administration of carbon tetrachloride (CCl(4)) in rats.

RESULTS

We showed that ADAMTS-13 antigen and proteolytic activity in the activated rat HSCs were dramatically increased, whereas ADAMTS-13 mRNA in these cells was only minimally altered. Similarly, the ADAMTS-13 antigen and proteolytic activity in rat liver after CCl(4) injury were also significantly increased, whereas the ADAMTS-13 mRNAs in these liver tissues were only slightly increased compared with normal. Surprisingly, despite the dramatic up-regulation of ADAMTS-13 protein synthesis in the activated HSCs after CCl(4) administration, the plasma levels of ADAMTS-13 protease in rats did not increase concordantly.

CONCLUSION

We conclude that the up-regulation of ADAMTS-13 protein expression in rat HSCs during activation in vitro and in vivo suggests the possibility of ADAMTS-13 proteolysis, an important part of function of the activated HSCs, perhaps through modulation of liver regeneration or formation of liver fibrosis after various injuries. The data also suggest the minimal contribution of the activated HSCs in regulation of plasma levels of ADAMTS-13 protease.

Interleukin-1alpha-induced proteolytic activation of metalloproteinase-9 by human skin

BACKGROUND

Increased activity of matrix metalloproteinase-9 (MMP-9) has been well documented in many diseases associated with inflammation, such as chronic wounds, bullous pemphigoid, liver failure, and tumor metastases. The mechanism for the proteolytic activation of pro-MMP-9 in human tissue still remains unknown.

METHODS

We investigated this mechanism through reconstitution of an inflammatory condition in normal human skin, and epidermal and dermal cells derived from skin. Normal human skin was cultured with exogenous cytokines associated with inflammation and tissue repair. MMP-9 induction and activation were measured, and potential mechanisms were probed by inhibitors.

RESULTS

Pathophysiologic concentrations of interleukin (IL)-1alpha rapidly induced pro-MMP-9 synthesis by human skin. In contrast, IL-1-induced activation of pro-MMP-9 was a slow process, which required 3 days. Tumor growth factor-beta induced pro-MMP-9 but failed to promote activation of the precursor. When the skin was stimulated with the combination of tumor growth factor-beta and IL-1alpha, substantial induction and activation of pro-MMP-9 occurred. This IL-1 induced activation of pro-MMP-9 was observed in intact skin but not in isolated dermal fibroblasts or keratinocytes. IL-1-induced activation of pro-MMP-9 was inhibited by chymostatin, a chymotrypsinlike proteinase inhibitor. Furthermore, IL-1alpha decreased tissue inhibitor of metalloproteinase 1 without changing MMP-9 activator activity.

CONCLUSIONS

The proteolytic activation of pro-MMP-9 in skin inflammatory diseases likely occurs via a pathway including IL-1alpha. The activation is mediated by downregulation of tissue inhibitor of MMP-1 and involves an as yet unidentified chymotrypsinlike proteinase.

Tissue distribution, inhibition and activation of gelatinolytic activities in Atlantic cod (Gadus morhua)

Gelatinolytic activities in fish tissues with properties like matrix metalloproteinases (MMPs) have been paid little attention. However, they have been proposed to participate in post mortem degradation during storage and the disintegration of pericellular connective tissue during spawning. In this paper the distribution of gelatinolytic activities in liver, heart, muscle, gill, and male and female gonad of Atlantic cod (Gadus morhua) was studied by using gelatin SDS-PAGE, proteinase inhibitors, gelatin and lentil lectin Sepharose affinity chromatography. The amount of gelatin degrading enzymes varied from tissue to tissue. Most of the gelatin binding enzymes were found to be matrix metalloproteinases by adding galardin, a broad range MMP inhibitor, to the incubation buffer. A 72 kDa form of cod gelatin degrading enzyme had properties similar to human proMMP-2, as it could be activated by p-aminophenylmercuric acetate and trypsin. Like the human MMP-2 it did not bind to lentil lectin. An 83 kDa cod gelatin degrading enzyme had properties similar to the 92 kDa progelatinase B (proMMP-9). These properties were also similar to that of the 72 kDa form, except that the 83 kDa cod gelatinase was bound to lentil lectin, showing that it is a glycoprotein like MMP-9.

Expression and localization of matrix metalloproteinases (MT1-MMP, MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) during synepitheliochorial placentation of goats (Capra hircus)

Matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) play key roles during the placentation of highly invasive haemochorial type. Our knowledge is yet scanty, however, regarding the roles played by MMPs and TIMPs in the placentation of non-invasive synepitheliochorial type. In the present study, expression patterns of MT1-MMP, MMP-2 and TIMP-2 mRNAs as well as the encoded proteins in the endometrium and the placenta were examined on Days 35, 75, and 100 of pregnancy, representing roughly the 1st, 2nd and 3rd trimesters of caprine gestation, by means of quantitative RT-PCR analysis, in situ hybridization, immunoblotting, gelatin zymography and immunohistochemistry. In the endometrium and the intercotyledonal trophoblast, the expression levels of the 3 genes remained relatively uniform throughout the period of gestation examined. Curiously, however, in the placentomes, the relative expression levels of MT1-MMP mRNA increased linearly from Day 35 to Day 100, while those of MMP-2 and TIMP-2 were clearly down-regulated in Day 100 placentae. The expression levels of MT1-MMP and TIMP-2 proteins in placentomes were well correlated with those of the respective mRNAs. In the case of MMP-2, the total amount of MMP-2 protein (the combined values of the latent, the intermediate and the active forms) decreased slightly, while the levels of the active form increased markedly from Day 35 to Day 100. Immunohistochemical analysis of the placentome revealed that MT1-MMP and TIMP-2 proteins were co-localized in the binucleate trophoblast cells; expression of these 2 proteins was not detected in the uninuclear principal trophoblast cells. MMP-2 expression was detected both in the binucleate and in the uninuclear principal cells of the trophoblast and in the endometrial stromal cells of the uterine septum, regardless of the stages of gestation examined. The co-localization of MT1-MMP, MMP-2 and TIMP-2 in binucleate trophoblast cells, the cotyledonal trophoblast cells and the subsyncytial stromal cells is likely to reflect the functional coordination of the 3 proteins in these cells during trophoblastic invasion and the placental tissue remodeling in the placentome.

Differential expression of extracellular matrix remodeling genes in rat model of hemorrhagic shock and resuscitation1,2

BACKGROUND

Matrix metalloproteinases (MMPs) and their specific physiological inhibitors, tissue inhibitors of metalloproteinases (TIMPs), are thought to play an essential role in tissue repair, cell death and morphogenesis. We have previously discovered unexpected up-regulation of genes coding for multiple MMP/TIMP family members in a rat model of hemorrhagic shock and resuscitation. However, the effect of different resuscitation protocols at the level of protein expression and function remains unknown.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n = 50; 10/group) were subjected to a three-stage volume controlled hemorrhage and resuscitated as follows: 1) lactated Ringer's solution (LR), 3:1 volume of lost blood; 2) 7.5% hypertonic saline (HTS), 9.7 ml/kg; 3) plasma, 1:1 volume. Sham hemorrhage and sham resuscitation groups were used as controls. Expression of lung and spleen MMPs (-2, -7, -9, -10, -14, and -16), and TIMPs (-1, -2, and -3) was analyzed at transcriptional, functional and protein expression level using RT-PCR, ELISA, Western blotting, and gelatin zymography techniques.

RESULTS

Spleen was affected more than lung by the resuscitation strategy and the largest number of changes was caused by HTS resuscitation. RT-PCR confirmed an increased levels of MMP-2, MMP-9, MMP-7, MMP-14, MMP-16, and TIMP-1, TIMP-2 in the spleen of HTS group compared to sham groups, whereas in lungs transcriptional levels of only TIMP-3 and TIMP-1 were significantly changed.

CONCLUSION

Expression of MMP and TIMP in lung and spleen following hemorrhage is modulated by the resuscitation strategy.

Matrix metalloproteinase inhibition in corneal ulceration

The primary objective of current treatment strategies for infectious keratitis is to sterilize the ulcer as rapidly as possible with topically administered antibiotics. Ulcerative processes can proceed in some cases, despite the absence of microbes, as a result of remaining corneal and tear film MMPs. Combining antibiotic therapy with MMP inhibitors can speed corneal healing, because MMPs play an important role in corneal ulceration and stromal liquefaction. MMPs from the rabbit, horse, and human being are inhibited by metal-binding agents EDTA, NAC, and doxycycline as well as by the serum antiprotease alpha2-macroglobulin. It is not yet certain which proteinase inhibitor has the most favorable therapeutic index for clinical use, although we prefer serum because of its effects on multiple types of proteinases. The MMP inhibitors do have significant therapeutic promise in the treatment of corneal ulceration.

MMP-2 activation and stepwise progression of pulmonary adenocarcinoma: Analysis of MMP-2 and MMP-9 with gelatin zymography

Small pulmonary adenocarcinomas can be classified on the basis of their histological characteristics and prognosis, and when classified as such, the prognosis of replacing-type adenocarcinoma with active fibroblast proliferation is significantly worse than adenocarcinoma without fibroblast proliferation. In order to clarify the biological mechanisms of the key to the morphological changes associated with active fibroblast proliferation, we examined the activities of matrix metalloproteinase (MMP)-2 and MMP-9, which are important enzymes in the stromal invasion by cancers. The active MMP-2 and MMP-9 content of 40 pulmonary adenocarcinomas that were less than 20 mm in diameter was measured by the gelatin zymography method. The quantity of active MMP-2 in the pulmonary adenocarcinomas with active fibroblast proliferation was higher than in the pulmonary adenocarcinomas without proliferation (P < 0.001), but there were no correlations between the histological features and the activation of MMP-9. The presence of active fibroblast proliferation in small pulmonary adenocarcinomas suggests that the cancer cells have acquired the ability to invade through the action of active MMP-2, and this is thought to be one of the reasons for the worse prognosis of pulmonary adenocarcinoma with active fibroblast proliferation.

Essential role of matrix metalloproteinases in interleukin-1-induced myofibroblastic activation of hepatic stellate cell in collagen

Located within the perisinusoidal space and surrounded by extracellular matrix, hepatic stellate cells (HSC) undergo phenotypic trans-differentiation called "myofibroblastic activation" in liver fibrogenesis. This study investigated the regulation of interleukin-1 (IL-1alpha) on expression of matrix metalloproteinases (MMPs) by HSC grown in three-dimensional extracellular matrix and the role of MMPs in HSC activation. To recapitulate the in vivo "quiescent" state of HSC, the isolated rat HSC were grown in three-dimensional Matrigel or type I collagen. Stimulation with IL-1alpha caused robust induction of pro-MMP-9 (the precursor of matrix metalloproteinase-9) when HSC were cultured in these matrices. IL-1alpha induced a conversion of the pro-MMP-9 to the active form only when the cells were in type I collagen. In collagen lattices, IL-1alpha provoked activation of HSC with induction of MMP-13, MMP-3, and breakdown of the matrix. The HSC activation was completely prevented by a treatment of the cells with tissue inhibitor of metalloproteinase-1 or deprivation of MMP-9. Once fully activated, HSC failed to express MMP-9 and showed attenuated induction of MMP-13 and MMP-3. Further, we demonstrated colocalization of alpha-smooth muscle actin and MMP-9 in a subpopulation of HSC in human fibrotic liver tissues. Thus, this study provides a novel model to enlighten the role of MMPs, particularly that of MMP-9, in HSC activation regulated by a specific cytokine in liver fibrogenesis.

Abnormal expression of matrix metalloproteinase-2 and -9 in interspecific pregnancy of rat embryos in mouse recipients

The high failure rate of interspecific pregnancy is a major obstacle to the successful interspecific cloning of mammals. Embryo transfer between rats and mice provides a unique model for studying the causes of such failures. Previous research has shown that the upper time limit for the survival of rat embryos in mouse uteri was the seventh day of pregnancy (Day 7). To study the reasons for the failure of interspecific pregnancy between rats and mice, we transferred rat blastocysts into mouse uteri on the third day of pseudopregnancy. Unexpectedly, intact rat embryos could still be observed in mouse uteri on Day 9 and the implantation rate was as high as 30.6%. However, compared with mouse embryos, the further development of transferred rat embryos in mouse uteri was retarded. On Day 10, transferred rat embryos shrank with much blood. From Day 11 on, they lost their intact structure and the recipient uteri developed dropsy. On Day 12, the embryos shrank further and completely separated from the mouse uteri. By Day 13, they had been absorbed without any remains. In an in vitro co-culture (CT) system, the attachment rate of rat embryos on a monolayer of mouse uterine epithelial cells was similar to that of mouse embryos, but the outgrowth rate of rat embryos was significantly lower. Further investigation by gelatin zymography showed that matrix metalloproteinase-2 (MMP-2) and metalloproteinase-9 (MMP-9) activities in transferred rat embryos was significantly less than in mouse embryos. The same result was obtained in the in vitro CT assay. These results suggest that rat embryos can complete adhesion but not the invasion when transferred into mouse uteri. The reduced invasive ability, and especially, the associated reduction of MMP-2 and -9 activity, is one of the reasons for the failure of interspecific pregnancy.

Temperospatial expression of matrix metalloproteinases 1, 2, 3, and 9 during early tooth development

Odontogenesis involves a complex series of processes including epithelial-mesenchymal interactions, morphogenesis, differentiation, fibrillogenesis, and mineralization. Extracellular (ECM) remodeling plays a critical role in the rapid morphological changes that accompany these events. It is proposed that matrix metalloproteinases (MMPs) participate in the remodeling of tooth-specific matrices that accompanies the developmental events. MMPs are zinc-requiring endopeptidases that are centrally involved in the controlled turnover of ECM components and are key to a varied range of developmental processes. Thus, the aim of this study was to examine the expression of MMPs 1, 2, 3, and 9 within the developing tooth germ of Wistar rats, using immunohistochemical localisation. During the bud stage, MMPs 1, 2, 3, and 9 were expressed within both epithelial and mesenchymal cells. Later on, during the cap stage, differential expression was observed; of note was the expression of MMP 3 within the enamel knot. This study reports the temperospatial expression of MMPs 1, 2, 3, and 9 during early tooth development, and points to them having a key role during this important developmental period.

Matrix metalloproteinases limit functional recovery after spinal cord injury by modulation of early vascular events

Inflammation in general and proteinases generated as a result are likely mediators of early secondary pathogenesis after spinal cord injury. We report that matrix metalloproteinase-9 (MMP-9) plays an important role in blood-spinal cord barrier dysfunction, inflammation, and locomotor recovery. MMP-9 was present in the meninges and neurons of the uninjured cord. MMP-9 increased rapidly after a moderate contusion spinal cord injury, reaching a maximum at 24 hr, becoming markedly reduced by 72 hr, and not detectable at 7 d after injury. It was seen in glia, macrophages, neutrophils, and vascular elements in the injured spinal cord at 24 hr after injury. The natural tissue inhibitors of MMPs were unchanged over this time course. MMP-9-null mice exhibited significantly less disruption of the blood-spinal cord barrier, attenuation of neutrophil infiltration, and significant locomotor recovery compared with wild-type mice. Similar findings were observed in mice treated with a hydroxamic acid MMP inhibitor from 3 hr to 3 d after injury, compared with the vehicle controls. Moreover, the area of residual white matter at the lesion epicenter was significantly greater in the inhibitor-treated group. This study provides evidence that MMP-9 plays a key role in abnormal vascular permeability and inflammation within the first 3 d after spinal cord injury, and that blockade of MMPs during this critical period attenuates these vascular events and leads to improved locomotor recovery. Our findings suggest that early inhibition of MMPs may be an efficacious strategy for the spinal cord-injured patient.

Matrix metalloproteinases limit functional recovery after spinal cord injury by modulation of early vascular events

Inflammation in general and proteinases generated as a result are likely mediators of early secondary pathogenesis after spinal cord injury. We report that matrix metalloproteinase-9 (MMP-9) plays an important role in blood-spinal cord barrier dysfunction, inflammation, and locomotor recovery. MMP-9 was present in the meninges and neurons of the uninjured cord. MMP-9 increased rapidly after a moderate contusion spinal cord injury, reaching a maximum at 24 hr, becoming markedly reduced by 72 hr, and not detectable at 7 d after injury. It was seen in glia, macrophages, neutrophils, and vascular elements in the injured spinal cord at 24 hr after injury. The natural tissue inhibitors of MMPs were unchanged over this time course. MMP-9-null mice exhibited significantly less disruption of the blood-spinal cord barrier, attenuation of neutrophil infiltration, and significant locomotor recovery compared with wild-type mice. Similar findings were observed in mice treated with a hydroxamic acid MMP inhibitor from 3 hr to 3 d after injury, compared with the vehicle controls. Moreover, the area of residual white matter at the lesion epicenter was significantly greater in the inhibitor-treated group. This study provides evidence that MMP-9 plays a key role in abnormal vascular permeability and inflammation within the first 3 d after spinal cord injury, and that blockade of MMPs during this critical period attenuates these vascular events and leads to improved locomotor recovery. Our findings suggest that early inhibition of MMPs may be an efficacious strategy for the spinal cord-injured patient.

Matrix metalloproteinase inhibitors: do they have a place in anticancer therapy?

Matrix metalloproteinases (MMPs) are a family of enzymes involved in degradation of extracellular matrix. An imbalance between MMPs and naturally occurring MMP inhibitors may cause excess extracellular matrix destruction, allowing cancer cells to invade surrounding tissues and metastasize, and permitting angiogenesis to occur. Inhibition of certain key MMPs may prevent angiogenesis, tumor growth, invasion, and metastasis. Gelatinases MMP-2 and MMP-9 are expressed during carcinogenesis and angiogenesis. Synthetic MMP inhibitors were designed to target these enzymes and potentially prevent the tumor growth and metastases associated with cancer.

Activation of macrophage promatrix metalloproteinase-9 by lipopolysaccharide-associated proteinases

LPS induces an up-regulation of promatrix metalloproteinase-9 (proMMP9) gene expression in cells of the monocyte/macrophage lineage. We demonstrate here that LPS preparations are also able to activate proMMP9 made by human macrophages or THP-1 cells via LPS-associated proteinases, which cleave the N-terminal propeptide at a site or sites close to the one cleaved upon activation with organomercurial compounds. LPS-associated proteinases are serine proteinases that are able to cleave denatured collagens (gelatin) and the mammalian serine proteinase inhibitor, alpha(1)-proteinase inhibitor, thereby pushing the balance of extracellular matrix turnover even further toward degradation. A low molecular mass, low affinity inhibitor of MMP9, possibly derived from the propeptide, is generated during proMMP9 activation. However, inhibition of the LPS-associated proteinases had no effect on proMMP9 synthesis, indicating that their proteolytic activity was not required for signaling the up-regulation of the proMMP9 gene.

Enzymes active in the areas undergoing cartilage resorption during the development of the secondary ossification center in the tibiae of rats aged 0-21 days: II. Two proteinases, gelatinase B and collagenase-3, are implicated in the lysis of collagen fibrils

In the transformation of the cartilaginous epiphysis into bone, the first indication of change in the surfaces destined for resorption is the cleavage of aggrecan core protein by unidentified matrix metalloproteinases (MMPs) (Lee et al., this issue). In cartilage areas undergoing resorption, the cleavage leaves as superficial, 6-microm-thick band of matrix, referred to as "pre-resorptive layer." This layer harbors G1-fragments of the aggrecan core protein within a framework of collagen-rich fibrils exhibiting various stages of degeneration. Investigation of this layer in every resorption area by gelatin histozymography and TIMP-2 histochemistry demonstrates the presence of an MMP whose histozymographic activity is inhibited by such a low dose of the inhibitor CT1746 as to identify it as gelatinase A or B. Attempts at blocking the histozymographic reactions with neutralizing antibodies capable of inhibiting either gelatinase A or B reveals that only those against gelatinase B do so. Immunostaining of sections with anti-gelatinase B IgG confirms the presence of gelatinase B in every pre-resorptive layer, that is, at the blind end of excavated canals (stage I; 6-day-old rats), at sites along the walls of the forming marrow space (stage II; 7days), at sites within the walls of this space as it becomes the ossification center (stage III; 9 days) and along the wall of the maturing center (stage IV; 10-21 days). We also report the presence of collagenase-3 in precisely the same sites, possibly as active enzyme, but this remains to be proven. Because the results reveal that collagenase-3 is present beside gelatinase B in every pre-resorptive layer and, because these sites exhibit various signs of degradation including fibrillar debris, reduction in fibril number, or overt loss, we propose that gelatinase B and collagenase-3 mediate the lysis of this pre-resorptive layer-most likely through a cooperative attack leading to the disintegration of the collagen fibril framework.

Transforming growth factor-beta - and tumor necrosis factor-alpha -mediated induction and proteolytic activation of MMP-9 in human skin

Both cytokines and matrix metalloproteinases (MMPs) are active during physiologic and pathologic processes such as cancer metastasis and wound repair. We have systematically studied cytokine-mediated MMP regulation. Cytokine-mediated proteinase induction and activation were initially investigated in organ-cultured human skin followed by determination of underlying cellular and molecular mechanisms using isolated skin cells. In this report we demonstrate that tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) synergistically induce pro-MMP-9 in human skin as well as isolated dermal fibroblasts and epidermal keratinocytes. Furthermore, TNF-alpha promotes proteolytic activation of pro-MMP-9 by conversion of the 92-kDa pro-MMP-9 to the 82-kDa active enzyme. This activation occurred only in skin organ culture and not by either isolated fibroblasts or keratinocyte, although the pro-MMP-9 activation could be measured in a cell-free system derived from TNF-alpha-activated skin. The cytokine-mediated induction of pro-MMP-9 in dermal fibroblasts was evident by increased mRNA. At the transcription level, we examined the cytokine-mediated transactivation of the 5'-region promoter of the human MMP-9 in dermal fibroblasts. The results demonstrated that TNF-alpha and TGF-beta could independently stimulate the 5'-flanking 670-base pair promoter. A TGF-beta-response element (-474) and an NF-kappaB-binding site (-601) were identified to be the cis-elements for TGF-beta or TNF-alpha activation, respectively. Taken together, these findings suggest a specific mechanism whereby multiple cytokines can regulate MMP-9 expression/activation in the cells of human skin. These results imply roles for these cytokines in the regulation of MMP-9 in physiologic and pathologic tissue remodeling.

Immunolocalization of matrix metalloproteinases in partial-thickness defects in pig articular cartilage. A preliminary report

BACKGROUND

Partial-thickness defects in mature articular cartilage do not heal spontaneously. Attempts at repair often result in limited integration between the repair tissue and the surrounding cartilage, with formation of chondrocyte clusters adjacent to a zone of cartilage necrosis. In wound repair, spatially and temporally controlled expression of matrix metalloproteinases and their inhibitors have been implicated in proteolytic degradation of damaged extracellular matrix components, but the sequence of events following damage to cartilage is unknown. To determine this sequence, we studied the distribution of matrix metalloproteinases and their inhibitors during early in vivo repair of partial-thickness defects in pig articular cartilage.

METHODS

With use of a model that elicits the ingrowth of mesenchymal cells into partial-thickness defects, partial-thickness defects were created in knee joint cartilage. The distributions of matrix metalloproteinase-1, 2, 3, 9, 13, and 14; tissue inhibitors of metalloproteinase-1 and 2; and the neoepitope DIPEN341 specifically generated following matrix metalloproteinase cleavage of aggrecan were determined by immunolocalization of repair tissue and surrounding cartilage excised from immature pigs during the first eight weeks of repair and from adult minipigs at eight days and three weeks.

RESULTS

Synthesis of matrix metalloproteinase-13 was usually confined to hypertrophic chondrocytes in immature cartilage and to the radial zone in adult cartilage. Following injury, strong induction of matrix metalloproteinase-13 synthesis was observed in chondrocyte clusters surrounding lesions in all of the animals. The migration of macrophages into defects was prominent at two and eight days, with synthesis and deposition of matrix metalloproteinase-9 onto damaged cartilage matrix and newly synthesized matrix in the defect. The DIPEN341 neoepitope was localized to damaged cartilage matrix at eight days and six weeks, indicating partial degradation of aggrecan. Focal synthesis of matrix metalloproteinase-1, 3, and 14 and of tissue inhibitor of metalloproteinase-1 occurred at later times, suggesting continuous remodeling of the increasingly compact repair tissue.

CONCLUSIONS

The expression of matrix metalloproteinase-13 by normal hypertrophic chondrocytes and the induction of synthesis in chondrocyte clusters adjacent to the zone of cartilage necrosis suggest that this enzyme participates in the pericellular proteolysis required for lacunar expansion. The localization of matrix metalloproteinase-9 to damaged cartilage matrix suggested matrix proteolysis, which was confirmed with DIPEN341 localization. Reduced matrix metachromasia persisted and was colocalized with DIPEN341 at six weeks. However, under the conditions investigated, there was only limited proteolytic degradation in the zone of cartilage necrosis. This may render the zone mechanically weakened, thereby contributing to subsequent instability of the region, and may form a barrier to integration of repair tissue with viable cartilage.

CLINICAL RELEVANCE

Osteoarthritis initially involves the superficial layers of cartilage. The development of procedures to promote the healing or repair of early defects will have major advantages in terms of disease alleviation as well as economic importance. Identification of the enzymes involved in the early repair of partial-thickness defects in articular cartilage is clinically relevant because proteolysis of damaged matrix has to take place in order for repair tissue to integrate with surrounding healthy cartilage.

Role of matrix metalloproteinase-9 in progression of mouse skin carcinogenesis

Invasion of malignant tumor cells is required for the formation of metastatic colonies. Uncontrolled expression of matrix metalloproteinase (MMP)-2 and MMP-9 is a critical part of the invasive potential of tumor cells and is affected by the balance between the enzymes and the inhibitors secreted by the cell. Here we analyzed the expression and activity of the two gelatinases (MMP-2 and MMP-9) as well as the expression levels of the tissue inhibitor of metalloproteinase (TIMP2)-, in different stages of carcinogenesis using mouse skin cell lines derived from tumors induced by chemical mutagens. Our results suggested that the expression of MMP-9 was implicated in the progression to spindle cell carcinomas in mouse keratinocytes. MMP-2 levels remained steady in all cell lines, whereas levels of TIMP-2 were increased in normal and spindle cells. The AP-1 DNA binding and transcriptional activity on the MMP-9 promoter were increased in the malignant cell lines, indicating the requirement of this binding site for its activation. The results of this study clearly suggested the important role of MMP-9, but not of MMP-2, in the metastatic properties of mouse keratinocytes.

Systematic separation and purification of elastase, gelatinase (matrix metalloproteinase 9), and collagenase (matrix metalloproteinase 8) from polymorphonuclear leukocytes in dialyzers previously used by patients with renal failure

We developed a simple and effective method for the systematic separation and purification of human polymorphonuclear leukocyte (PMN) proteinases, elastase, gelatinase (matrix metalloproteinase 9, type IV collagenase), and collagenase (matrix metalloproteinase 8), derived from the extracts of hollow fiber dialyzers that had been utilized in the treatment of patients with renal failure. The fraction containing elastase was grossly separated from that containing gelatinase and collagenase by heparin-Sepharose chromatography and purified in an aprotinin column. The remaining two enzymes were then separated using the gelatin-Sepharose column after gel chromatography following ammonium sulfate precipitation. Gelatinase and collagenase were further purified by gelatin-Sepharose chromatography as a latent form and by collagen-Sepharose chromatography as an activated form. This novel method offers procedural advantages over existing methods that separate PMNs from the whole blood of volunteers for experimental research purposes.

Matrix Metalloproteinases (MMP-2 and MMP-9) and Tissue Inhibitor-2 of Matrix Metalloproteinases (TIMP-2) in the Placenta and Interplacental Uterine Wall in Normal Cows and in Cattle with Retention of Fetal Membranes

Matrixmetalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) play a key role in tissue re-modelling in the placenta. In the present study, distribution of MMP-2, MMP-9 and TIMP-2 was demonstrated immunohistochemically in the bovine placenta and interplacentomal tissue. Specimens representing the whole gestation until parturition were processed. Additionally, materials from cows with and without retention of fetal membranes were compared. MMP-2 expression was abundant in the maternal septae of the placentome in early gestation, with ongoing pregnancy immunoreactivity was restricted to the stromal tissue at the openings of maternal crypts. The chorionic epithelium opposite to these regions was also positive for MMP-2. MMP-9 expression was observed in the chorionic epithelium, except in the giant binucleate cells. In addition, the maternal epithelium and stroma showed immunoreactivity for MMP-9. No differences in MMP-2 and MMP-9 distribution could be observed between cows with proper release of fetal membranes and cows with retained fetal membranes. Giant binucleate cells expressed TIMP-2 during the whole gestation. Immunostaining for alpha-smooth muscle actin revealed contractile elements in the bovine placentome. Balance between proteolytic enzymes and their activators and inhibitors is essential for regular development of the placenta. The expression of TIMP-2 in the giant binucleate cells indicates an essential role of inhibitory factors during gestation. It is likely that less TIMP-2 is produced at the end of pregnancy as the number of binucleate cells is diminished.

Acute exercise induced changes in rat skeletal muscle mRNAs and proteins regulating type IV collagen content

This experiment tested the hypothesis that running-induced damage to rat skeletal muscle causes changes in synthesis and degradation of basement membrane type IV collagen and to proteins regulating its degradation. Samples from soleus muscle and red and white parts of quadriceps femoris muscle (MQF) were collected 6 h or 1, 2, 4, or 7 days after downhill running. Increased muscle beta-glucuronidase activity indicated greater muscle damage in the red part of MQF than in the white part of MQF or soleus. In the red part of MQF, type IV collagen expression was upregulated at the pretranslational level and the protein concentration decreased, whereas matrix metalloproteinase-2 (MMP-2), a protein that degrades type IV collagen, and tissue inhibitor of metalloproteinase-2 (TIMP-2), a protein that inhibits degradation, were increased in parallel both at mRNA and protein levels. Type IV collagen mRNA level increased in the white part of MQF and soleus muscle. The protein concentration increased in the white part of MQF and was unchanged in soleus muscle. MMP-2 and TIMP-2 changed only slightly in the white part of MQF and soleus muscle. The changes seem to depend on the severity of myofiber injury and thus probably reflect reorganization of basement membrane compounds.

Enzymatic, clinical and histologic evaluation of corneal tissues in experimental fungal keratitis in rabbits

Mycotic keratitis, being frequently refractive to most of the currently available antifungal therapy, continues to pose a therapeutic challenge to the clinician. In keratitis of infectious etiology stromal dissolution may be brought about by a combination of agent and host factors. An understanding of the source and nature of corneal tissue damage is essential for evolving more effective therapeutic modalities in the treatment of fungal keratitis. In the present study, we have characterized the extracellular proteases produced in vitro by corneal fungal pathogens namely the Aspergillus flavus and Fusarium solani when collagen was provided as the sole nitrogen source. In addition, fungal infected rabbit corneas were investigated for proteolytic activities and nature of inflammatory reaction. Gelatin zymography detected protease bands with molecular mass ranging from 100 to 200 kDa in the culture extracts of A. flavus, and a single major band of molecular mass approximately 200 kDa in the culture extracts of F. solani. A basal proteolytic activity of mass 65 kDa was visualized in all uninfected and infected rabbit corneal extracts. Infected corneas in addition revealed the presence of additional proteolytic species of mass 92 and 200 kDa. The enzyme inhibitory profile suggested that fungal cultures in vitro contained predominantly serine protease activity and to a lesser extent metalloprotease activity. However, fungal infected corneal homogenates showed the presence of metalloproteinase activity alone, the enzymatic activities entirely being sensitive to ethylene diamine tetra acetate (EDTA), a metalloprotease inhibitor. Interestingly, the serine proteolytic activity detected in fungal cultures in vitro was not present in the fungal infected corneas in vivo. However, the possible role of fungal serine proteases in the activation of corneal matrix metalloproteinases (MMPs) cannot be ruled out. Based on the criteria of molecular mass, proteolytic activity in the presence of calcium at neutral pH, and sensitivity to inhibition by a metalloprotease inhibitor, the 65 and 92 kDa gelatinases were identified as MMP 2 and MMP 9, respectively. The expression of 92 and 200 kDa gelatinases correlated positively with the amount of polymorphonuclear cells present in the infected tissues. Activated resident corneal cells or inflammatory cells may largely contribute to the increased proteolytic activities in fungal infected corneas resulting in tissue matrix degradation in fungal keratitis.

Tear film MMP accumulation and corneal disease

BACKGROUND/AIMS

Matrix metalloproteinases (MMPs) accumulate in the tears of patients with active peripheral ulcerative keratitis (PUK) but it is unknown whether these enzymes have a central role in disease progression. The aims of the present investigation were to determine the source of these enzymes and to ascertain whether their accumulation in tears is a phenomenon specific to PUK or a general feature of other anterior segment diseases.

METHODS

The experimental samples were obtained from the culture media of conjunctival and corneal epithelial cells, from fractionated blood plasma and leucocytes of healthy subjects and patients with rheumatoid arthritis, and from the tears of healthy subjects and patients with a variety of anterior segment diseases. The MMPs of all samples were visualised by zymography and tear samples were assayed using nitrophenol acetate and an MMP-9 susceptible quenched fluorescent peptide as substrate.

RESULTS

The major MMPs that accumulate in the tears of patients with rheumatoid arthritis with active ocular disease are MMP-9 and a species of M(r) 116,000. By comparing the zymographic activity profiles of the gelatinases present in the samples obtained, it was deduced that the main source of these MMPs was granulocytes. Their accumulation in tears was not unique to patients with PUK; detectable amounts of the enzymes also occurred in the tears of patients with keratoconus with associated atopic disease, patients undergoing treatment for herpetic eye disease, and patients with systemic and non-systemic dry eye disease.

CONCLUSION

The MMPs that accumulate in tears are mainly derived from granulocytes. This may be effected by autoimmune diseases that involve ocular tissue or by ocular diseases that induce an inflammatory response.

Quantitative analysis of mRNA expression of TIMPs in the periprosthetic interface tissue of loose hips by real-time PCR system

Matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs), have been reported to play a critical role in extracellular degradation around artificial hip joints. Although messenger ribonucleic acid (mRNA) expression patterns of several MMPs and TIMPs were reported, there is no report of quantitative mRNA analysis of TIMPs in periprosthetic tissues. In this study, mRNA expression of four different types of TIMPs in periprosthetic interface tissue of loose hips was analyzed by a quantitative polymerase chain reaction system. The mRNA expression level of TIMP-1, -2, and -3 in periprosthetic interface tissue was significantly higher than that in control. In contrast, the mRNA expression level of TIMP-4 in the periprosthetic interface tissue was lower. This study suggested that increased levels of TIMP-1, -2, and -3, and decreased levels of TIMP-4 may contribute to pathologic extracellular matrix degradation in combination with MMPs, thus leading to prosthetic loosening and osteolysis around artificial total hip joints.

The integrin linked kinase (ILK) induces an invasive phenotype via AP-1 transcription factor-dependent upregulation of matrix metalloproteinase 9 (MMP-9)

Overexpression of Integrin Linked Kinase (ILK) in intestinal and mammary epithelial cells results in a highly invasive phenotype, associated with increased levels of expression of the matrix metalloproteinase MMP-9. This increase was at the transcriptional level as determined by MMP-9 promoter-CAT reporter assays. Mutations in the two AP-1 binding sites within the MMP-9 promoter completely inhibited the reporter activity. We have previously shown that ILK inhibits glycogen synthase kinase-3 (GSK-3) activity. Transient transfection of wild-type GSK-3beta in ILK-overexpressing cells decreased MMP-9 promoter activity and AP-1 activity, indicating that ILK can stimulate MMP-9 expression via GSK-3beta and AP-1 transcription factor. A small molecule inhibitor of the ILK kinase reduced the in vitro invasiveness of ILK-overexpressing cells as well as the invasiveness of several human brain tumor cell lines. Furthermore, both MMP-9 promoter and AP-1 activities were inhibited by the ILK inhibitor. Invasiveness of ILK-overexpressing cells was also reduced by inhibition of MMP-9. These data demonstrate that ILK can induce an invasive phenotype via AP-1-dependent upregulation of MMP-9.