Role of matrix metalloproteinases in normal and disease processes

The Trinity of Matrix Metalloproteinases, Inflammation, and Cancer: A Literature Review of Recent Updates

The critical link between cancer and inflammation has been known for many years. This complex network was further complexed by revealing the association of the matrix metalloproteinase family members with inflammatory cytokines, which were previously known to be responsible for the development of metastasis. This article summarizes the current studies which evaluate the relationship between cancer and inflammatory microenvironment as well as the roles of MMPs on invasion and metastasis together.

Protective Effects of Phellinus linteus Mycelium on the Development of Osteoarthritis after Monosodium Iodoacetate Injection

Objective

The aim of this study was to identify the protective effects of Phellinus linteus mycelium (PLM) and its possible mechanisms in a model of monosodium iodoacetate- (MIA-) induced osteoarthritis (OA).

Methods

Intra-articular injection of MIA was injected to 50 μL with 80 mg/mL using a 0.3 mL insulin syringe into the right knee joint. Changes in hindpaw weight-bearing distribution between the right (osteoarthritic) and left (contralateral control) legs were used as an index of joint discomfort. PLM (50, 100, and 200 mg/kg body weight) was orally administered once daily for 14 days from day 7 after MIA treatment. And then, various factors associated with inflammatory response and cartilage degeneration in cartilage tissues detected by western blotting.

Results

PLM treatment showed a concentration-dependent elevation in change in hindpaw weight-bearing distribution (HWBD). PLM200 demonstrated the capacity to significantly increase HWBD, indicating that the change in weight-bearing distribution means the reduction of spontaneous pain. Our results indicate that PLM suppressed the inflammatory factors via NF-κB signaling pathway induced by p38 phosporlyation. Moreover, PLM200 exhibited a significant reduction of ROS produced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. PLM100 and PLM200 inhibited the levels of matrix metalloproteinase (MMP)-1, one of proteinase that degrades extracellular matrix (ECM).

Conclusions

Taken together, our results indicated that PLM has a strong chondroprotective effect through the suppression both ROS production and inflammation.

Expression of collagenases (matrix metalloproteinase-1, 8, 13) and tissue inhibitor of metalloproteinase-1 of retrodiscal tissue in temporomandibular joint disorder patients

OBJECTIVES

The aim of this study was to reveal how collagenases (matrix metalloproteinase [MMP]-1, 8, 13) and tissue inhibitor of metalloproteinase 1 (TIMP-1) are expressed in immunohistochemistry of retrodiscal tissue in temporomandibular joint disorder patients.

MATERIALS AND METHODS

This study was conducted on 39 patients who underwent discoplasty or discectomy. Immunohistochemical staining was undertaken and expression levels of MMP-1, 8, 13, and TIMP-1 were evaluated. The status of internal derangement of disc, osteoarthritis, and joint effusion were analyzed using magnetic resonance imaging (MRI). Disc status observed during operation was also categorized.

RESULTS

The more severe disc derangement was observed on MRI, the more increased expression of MMPs and TIMP-1 appeared. Regarding MMP-13 expression, 86.7% of late-stage disc displacement patients showed grade II or III. Expression level of MMPs or TIMP was not statistically significant associated with joint effusion level. In perforation and/or adhesion groups, all patients showed grade II or III expression of MMP-13. Once perforation occurred, MMP-13 showed increased expression with statistical significance.

CONCLUSION

MMP-1 and MMP-13 expression seem to be related to progression of osteoarthritis whereas MMP-8 does not seem to have a specific role with regard to temporomandibular joint disorders. TIMP-1 is considered to be partly related to internal derangement rather than osteoarthritis, but it is not significant.

Vascular Endothelial Dysfunction in Inflammatory Bowel Diseases: Pharmacological and Nonpharmacological Targets

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are chronic inflammatory conditions involving primarily the gastrointestinal tract. However, they may be also associated with systemic manifestations and comorbidities. The relationship between chronic inflammation and endothelial dysfunction has been extensively demonstrated. Mucosal immunity and gastrointestinal physiology are modified in inflammatory bowel diseases, and these modifications are mainly sustained by alterations of endothelial function. The key elements involved in this process are cytokines, inflammatory cells, growth factors, nitric oxide, endothelial adhesion molecules, and coagulation cascade factors. In this review, we discuss available data in literature concerning endothelial dysfunction in patients affected by inflammatory bowel disease and we focus our attention on both pharmacological and nonpharmacological therapeutic targets.

Matrix metalloproteinase activity and prostaglandin E2 are elevated in the synovial fluid of meniscus tear patients

PURPOSE

Meniscus tears are a common knee injury and are associated with the development of post-traumatic osteoarthritis (OA). The purpose of this study is to evaluate potential OA mediators in the synovial fluid and serum of meniscus tear subjects compared to those in the synovial fluid of radiographic non-OA control knees.

MATERIALS AND METHODS

Sixteen subjects with an isolated unilateral meniscus injury and six subjects who served as reference controls (knee Kellgren-Lawrence grade 0-1) were recruited. Twenty-one biomarkers were measured in serum from meniscus tear subjects and in synovial fluid from both groups. Meniscus tear subjects were further stratified by tear type to assess differences in biomarker levels.

RESULTS

Synovial fluid total matrix metalloproteinase (MMP) activity and prostaglandin E2 (PGE2) were increased 25-fold and 290-fold, respectively, in meniscus tear subjects as compared to reference controls (p < 0.05). Synovial fluid MMP activity and PGE2 concentrations were positively correlated in meniscus tear subjects (R = 0.83, p < 0.0001). In meniscus tear subjects, synovial fluid levels of MMP activity, MMP-2, MMP-3, sGAG, COMP, IL-6, and PGE2 were higher than serum levels (p < 0.05). Subjects with complex meniscus tears had higher synovial fluid MMP-10 (p < 0.05) and reduced serum TNFα and IL-8 (p < 0.05) compared to other tear types.

CONCLUSIONS

Given the degradative and pro-inflammatory roles of MMP activity and PGE2, these molecules may alter the biochemical environment of the joint. Our findings suggest that modulation of PGE2 signaling, MMP activity, or both following a meniscus injury may be targets to promote meniscus repair and prevent OA development.

A Comprehensive Transcriptomic and Proteomic Analysis of Hydra Head Regeneration

The cnidarian freshwater polyp Hydra sp. exhibits an unparalleled regeneration capacity in the animal kingdom. Using an integrative transcriptomic and stable isotope labeling by amino acids in cell culture proteomic/phosphoproteomic approach, we studied stem cell-based regeneration in Hydra polyps. As major contributors to head regeneration, we identified diverse signaling pathways adopted for the regeneration response as well as enriched novel genes. Our global analysis reveals two distinct molecular cascades: an early injury response and a subsequent, signaling driven patterning of the regenerating tissue. A key factor of the initial injury response is a general stabilization of proteins and a net upregulation of transcripts, which is followed by a subsequent activation cascade of signaling molecules including Wnts and transforming growth factor (TGF) beta-related factors. We observed moderate overlap between the factors contributing to proteomic and transcriptomic responses suggesting a decoupled regulation between the transcriptional and translational levels. Our data also indicate that interstitial stem cells and their derivatives (e.g., neurons) have no major role in Hydra head regeneration. Remarkably, we found an enrichment of evolutionarily more recent genes in the early regeneration response, whereas conserved genes are more enriched in the late phase. In addition, genes specific to the early injury response were enriched in transposon insertions. Genetic dynamicity and taxon-specific factors might therefore play a hitherto underestimated role in Hydra regeneration.

Tgfbi deficiency leads to a reduction in skeletal size and degradation of the bone matrix

Transforming growth factor-β-induced gene product-h3 (TGFBI/BIGH3) is an extracellular matrix protein expressed in a wide variety of tissues. TGFBI binds to type I, II, and IV collagens, as well as to biglycan and decorin and plays important roles in cell-to-cell, cell-to-collagen, and cell-to-matrix interactions. Furthermore, TGFBI is involved in cell growth and migration, tumorigenesis, wound healing, and apoptosis. To investigate whether TGFBI is involved in the maintenance of skeletal tissues, Tgfbi knockout mice were generated by crossing male and female Tgfbi heterozygous mice. Skeletal preparation showed that the skeletal size in Tgfbi knockout mice was smaller than in wild-type and heterozygous mice. However, chondrocytic cell alignment in the growth plates, bone mineral density, and bone forming rates were similar in Tgfbi knockout, wild-type, and heterozygous mice. Alterations in skeletal tissue arrangements in Tgfbi knockout mice were estimated from safranin O staining, trichrome staining, and immunohistochemistry for type II and X collagen, and matrix metalloproteinase 13 (MMP13). Cartilage matrix degradation was observed in the articular cartilage of Tgfbi knockout mice. Although the detection of type II collagen in the articular cartilage was lower in Tgfbi knockout mice than wild-type mice, the detection of MMP13 was markedly higher, indicating that Tgfbi deficiency is associated with the degradation of cartilage matrix. These results suggest that TGFBI plays an important role in maintaining skeletal tissues and the cartilage matrix in mice.

PEG10 plays a crucial role in human lung cancer proliferation, progression, prognosis and metastasis

Paternally expressed gene 10 (PEG10) has been identified as a genetic imprinted gene, which is important for apoptosis resistance in cancer cells. Mounting evidence suggests that PEG10 is expressed in the majority of hepatocellular carcinoma (HCC) cells with growth-promoting activity. In the present study, we evaluated the correlation between PEG10 expression and the clinicopathological features of lung, breast and HCC tumors, and predicted the relationship between survival and expression levels of PEG10 in lung cancer patients. Furthermore, we chose non-small cell lung cancer cell line A549 as a model to analyze the function of PEG10 in proliferation and metastasis in vitro. Our results revealed that expression of PEG10 was closely correlated with clinical TNM grade and patient prognosis in lung cancer. PEG10 enhanced cell proliferation and promoted tumor cell migration and invasion by upregulating the expression of β-catenin, MMP-2 and MMP-9, and decreased the expression of E-cadherin in the A549 cells. Our findings provide significant insight into the molecular mechanisms of lung cancer and offer novel ideas for designing new therapeutic targets for lung carcinoma.

Combination of Sasa quelpaertensis Nakai Leaf Extract and Cisplatin Suppresses the Cancer Stemness and Invasion of Human Lung Cancer Cells

Lung cancer is the leading cause of cancer death worldwide, and most chemotherapeutic drugs have limited success in treating this disease. Furthermore, some drugs show undesirable side effects due to the enrichment of cancer stem cells (CSCs) that are present, leading to resistance to conventional chemotherapy and tumor relapse. CSCs possess self-renewal characteristics, aggressive tumor initiating activity, and ability to facilitate tumor metastasis. Therefore, development of nontoxic agents that can potentiate chemotherapy and eliminate CSCs would be highly desirable. In the present study, we investigated whether Sasa quelpaertensis leaf extracts (SQE) and cisplatin (CIS), individually or in combination, would exert anti-CSC and antimetastatic effect in H1299 and A549 human lung cancer cells. Following these treatments, cell growth, phosphorylation of phosphoinositide-3 kinase, and activation of the mammalian target of rapamycin were inhibited. Decreased serial sphere formation, clonogenicity, and expression of major stem cell markers, such as CD44 and SOX-2, in CD44+ cancer stem cells were also observed. In addition, inhibition of cell migration and invasion in both cell lines as well as inhibition of matrix metalloproteinase-2 activity and expression were detected. Importantly, the anticancer stemness and antimetastasis effects in each of these assays were greater for the combined treatment with SQE and CIS than with each treatment individually. In conclusion, the data suggest that SQE alone, or in combination with CIS, represents a promising therapeutic strategy for eliminating cancer stemness and cell invasion potential of CSCs, thereby treating and preventing metastatic lung cancer cells.

Molecular mechanism of force induced stabilization of collagen against enzymatic breakdown

Collagen cleavage, facilitated by collagenases of the matrix metalloproteinase (MMP) family, is crucial for many physiological and pathological processes such as wound healing, tissue remodeling, cancer invasion and organ morphogenesis. Earlier work has shown that mechanical force alters the cleavage rate of collagen. However, experimental results yielded conflicting data on whether applying force accelerates or slows down the degradation rate. Here we explain these discrepancies and propose a molecular mechanism by which mechanical force might change the rate of collagen cleavage. We find that a type I collagen heterotrimer is unfolded in its equilibrium state and loses its triple helical structure at the cleavage site without applied force, possibly enhancing enzymatic breakdown as each chain is exposed and can directly undergo hydrolysis. Under application of force, the naturally unfolded region refolds into a triple helical structure, potentially protecting the molecule against enzymatic breakdown. In contrast, a type I collagen homotrimer retains a triple helical structure even without applied force, making it more resistant to enzyme cleavage. In the case of the homotrimer, the application of force may directly lead to molecular unwinding, resulting in a destabilization of the molecule under increased mechanical loading. Our study explains the molecular mechanism by which force may regulate the formation and breakdown of collagenous tissue.

Matrix metalloproteinases (MMPs) activity in cultured canine bone marrow stromal cells (BMSCs)

Autologous bone marrow stromal cells (BMSCs) infusion therapy improves the hepatic fibrosis. To investigate the mechanism of remission, we evaluated the matrix metalloproteinase (MMP)-2 and -9 activity in canine BMSCs and the effect of pro-inflammatory cytokines on their expression. The activity and the gene expression of MMPs were analyzed by gelatin zymography and quantitative RT-PCR, respectively. The specific gelatinase bands were indicative effect of MMP-2 and -9 in canine BMSCs. MMP-2 expression seemed to be increased by TNF-α and IL-1β while MMP-9 was enhanced by TNF-α and IL-6. These results suggested that remissive effect on liver fibrosis might be partly attributable to the MMP-2 and -9 activity in BMSCs under the inflammatory condition.

In search of blood tests for thoracic aortic diseases

A number of new diagnostic screening tools have been developed for the assessment of acute and chronic diseases of the thoracic aorta. Although standardized blood-based tests capable of detecting individuals at risk for aortic aneurysm and dissection disease are not yet available, our current knowledge is expanding at a rapid rate and the future is very promising. In this review, an update of the contemporary knowledge on blood tests for detecting thoracic aortic diseases in both preclinical and clinical settings is provided, offering the potential to predict adverse aortic events, such as enlargement, rupture, and dissection.

Cleavage site specificity and conformational selection in type I collagen degradation

Excessive degradation of type I collagen is associated with a variety of human diseases such as arthritis, tumor metastasis, and atherosclerosis. Methods that further our understanding of collagenolysis may therefore provide insights into the mechanism of several important disorders. Prior experiments suggest that cleavage of collagen in vitro requires intact full-length collagenase, a multidomain protein containing both a catalytic and a hemopexin-like domain. In this work we demonstrate that type I collagen can be degraded at room temperature, a temperature well below the melting temperature of type I collagen, by collagenase deletion mutants that only contain the catalytic domain of the enzyme. Furthermore, these mutant enzymes hydrolyze the same peptide bond that is recognized by the corresponding full-length enzymes. Hence enzyme specificity at room temperature is achieved without the hemopexin-like domain. We demonstrate that these findings can be explained in light of a conformational selection mechanism that dictates that collagenases preferentially recognize and cleave preformed partially unfolded states of collagen.

Conformational selection and collagenolysis in type III collagen

Matrix metalloproteases (MMPs) cleave native collagen at a single site despite the fact that collagen contains more than one scissile bond that can, in principle, be cleaved. For peptide bond hydrolysis to occur at one specific site, MMPs must (1) localize to a region near the unique scissile bond, (2) bind residues at the catalytic site that form the scissile bond, and (3) hydrolyze the corresponding peptide bond. Prior studies suggest that for some types of collagen, binding of noncatalytic MMP domains to amino acid sequences in the vicinity of the true cleavage site facilitates the localization of collagenases. In the present study, our goal was to determine whether binding to the catalytic site also plays a role in determining MMP specificity. To investigate this, we computed the conformational free energy landscape of Type III collagen at each potential cleavage site. The free energy profiles suggest that although all potential cleavage sites sample unfolded states at relatively low temperatures, the true cleavage site samples structures that are complementary to the catalytic site. By contrast, potential cleavage sites that are not cleaved sample states that are relatively incompatible with the MMP active site. Furthermore, our findings point to a specific role for arginine residues in modulating the structural stability of collagen near the collagenase cleavage site. These data imply that locally unfolded potential cleavage sites in Type III collagen sample distinct unfolded ensembles, and that the region about the true collagenase cleavage site samples states that are most complementary to the MMP active site.

Protein levels of CC chemokine ligand (CCL)15, CCL16 and macrophage stimulating protein in patients with sarcoidosis

The objective of this study was to assess protein levels for candidate cytokines, chemokines, growth factors, matrix metalloproteinases and their inhibitors in bronchoalveolar lavage fluid (BALF) in patients with polar forms of pulmonary sarcoidosis, i.e. Löfgren's syndrome (LS) and more advanced chest X-ray (CXR) stage III disease. Twenty-four inflammatory molecules were analysed in unconcentrated BALF samples from 10 sarcoidosis patients with CXR stage III and 10 patients with LS by semiquantitative protein array. Four novel molecules [CC chemokine ligand (CCL)15, CCL16, macrophage migration inhibitory factor (MIF) and macrophage stimulating protein (MSP)], detected for the first time in association with sarcoidosis, were then quantified by enzyme-linked immunosorbent assay in a second cohort of 68 sarcoidosis patients and 17 control subjects. The protein levels of CCL15, CCL16, CCL24, CXCL8, CXCL9, CXCL10, interleukin-16, MIF, MSP and matrix metallopeptidase 1 were increased in CXR stage III patients when compared with patients with LS. CCL15 and MSP up-regulation in CXR stage III patients in comparison with LS patients and controls was confirmed by enzyme-linked immunosorbent assay. Moreover, MSP was associated with treatment requirement (P = 0.001) and CCL15 was elevated in patients with disease progression at 2-year follow-up (P = 0.016). CCL16 levels were increased in sarcoidosis versus controls (P < 0.05), but no difference was observed between patient subgroups. MIF up-regulation was not confirmed in a larger patient group. In conclusion, chemokines CCL15, CCL16 and MSP were found elevated for the first time in BALF from sarcoidosis patients; our results showed that CCL15 and MSP may affect disease course.

Matrix Metalloproteinase-2 and Matrix Metalloproteinase-9 Expression in Canine and Feline Meningioma

Fifty-one meningiomas obtained from 28 dogs and 23 cats were selected for this study to investigate the immunohistochemical expression of matrix metalloproteinase (MMP)-2 and MMP-9 and to compare it to the reverse transcriptase subunit of human-telomerase, progesterone receptor expression, and the proliferative index of the tumors, expressed by Ki67 and proliferating cellular nuclear antigen. Paraffin-embedded tumor tissue was obtained from biopsy samples (28 cases) and at necropsy (23 cases). The most common histotype was malignant in dogs (12/28) and transitional in cats (12/23). Slides immunolabelled for MMPs showed a diffuse cytoplasmic pattern. Twenty-one cases (19 dogs and 2 cats) did not express MMP-2, while only 2 cases were completely negative for MMP-9. The highest values of MMP-2 and MMP-9 were observed in a psammomatous and meningothelial tumor, respectively. On statistical analysis, MMP-2 expression did not show a significant correlation with MMP-9. Moreover, both MMP expressions failed to show significant variance among histologic patterns of the tumor and correlation with the proliferative index. MMP immunolabeling showed an inconstant correlation with progesterone receptor expression. No significant correlation was found between MMP and reverse transcriptase subunit of human-telomerase expression. In feline meningiomas, the MMP-2 value was significantly higher than in canine tumors and the MMP-9 value tended to be low for meningiomas with a follow-up duration from the 23rdmonth to the 44thmonth. In cats, the longer the time from surgery, the lower the proliferative index seemed to be. In dogs, we failed to find a correlation between MMP expression and the follow-up duration.

Differential unfolding of alpha1 and alpha2 chains in type I collagen and collagenolysis

Collagenolysis plays a central role in many disease processes and a detailed understanding of the mechanism of collagen degradation is of immense interest. While a considerable body of information about collagenolysis exists, the details of the underlying molecular mechanism are unclear. Therefore, to further our understanding of the precise mechanism of collagen degradation, we used molecular dynamics simulations to explore the structure of human type I collagen in the vicinity of the collagenase cleavage site. Since post-translational proline hydroxylation is an important step in the synthesis of collagen chains, we used the DNA sequence for the alpha1 and alpha2 chains of human type I collagen, and the known amino acid sequences for bovine and chicken type I collagen, to infer which prolines are hydroxylated in the vicinity of the collagenase cleavage site. Simulations of type I collagen in this region suggest that partial unfolding of the alpha2 chain is energetically preferred relative to unfolding of alpha1 chains. Localized unfolding of the alpha2 chain leads to the formation of a structure that has disrupted hydrogen bonds N-terminal to the collagenase cleavage site. Our data suggest that this disruption in hydrogen bonding pattern leads to increased chain flexibility, thereby enabling the alpha2 chain to sample different partially unfolded states. Surprisingly, our data also imply that alpha2 chain unfolding is mediated by the non-hydroxylation of a proline residue that is N-terminal to the cleavage site in alpha1 chains. These results suggest that hydroxylation on one chain (alpha1) can affect the structure of another chain (alpha2), and point to a critical role for the non-hydroxylation of proline residues near the collagenase cleavage site.

Extracellular matrix turnover and disease severity in Anderson-Fabry disease

BACKGROUND

Anderson-Fabry Disease (AFD) is an inherited metabolic disease associated with premature death secondary to cardiovascular and renal disease. Patients with AFD develop progressive left ventricular (LV) remodelling and heart failure. We hypothesized that altered extracellular matrix (ECM) turnover contributes to the pathophysiology of cardiac disease in AFD.

METHODS AND RESULTS

Twenty-nine consecutive patients (44.1 +/- 11.7 years, 15 male) with AFD and 21 normal controls (39.7 +/- 11.3 years, 10 male) had serum analysed for matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of matrix metalloproteinase-1 and -2 (TIMP-1, TIMP-2). All patients underwent clinical assessment, echocardiography and Mainz Severity Score Index (MSSI) measurement, a validated severity score in AFD. MMP-9 levels were significantly higher in patients than controls (1003.8 +/- 337.8 ng/ml vs 576.7 +/- 276.3 ng/ml respectively, p < 0.001). There were no differences in TIMP levels between patients and controls. There was a positive correlation between MMP-9 levels and MSSI (r = 0.5, p = 0.01). There was a negative correlation between MMP-9 and endocardial fractional shortening (FS) (r = -0.5, p = 0.01) and mid-wall FS (r = -0.6, p = 0.001). There was no correlation between other echocardiographic parameters and MMP-9 levels. These relations were independent of age and sex using stepwise linear regression analysis.

CONCLUSIONS

Patients with AFD have abnormal ECM turnover compared to normal controls. The correlation between MMP-9 levels and systolic function suggests that altered ECM turnover is important in cardiac remodelling. The association between MMP-9 and overall disease severity suggests that circulating levels of MMP-9 may provide a useful marker for assessing the response of patients with AFD to enzyme replacement treatment.

Chronic Matrix Metalloproteinase Inhibition Following Myocardial Infarction in Mice: Differential Effects on Short and Long-Term Survival

Left ventricular (LV) remodeling occurs after myocardial infarction (MI), and the matrix metalloproteinases (MMPs) contribute to adverse LV remodeling after MI. Short-term pharmacological MMP inhibition (MMPi; days to weeks) in animal models of MI have demonstrated a reduction in adverse LV remodeling. However, the long-term effects (months) of MMPi on survival and LV remodeling after MI have not been examined. MI was induced in adult mice (n = 131) and, at 3 days post-MI, assigned to MMPi [MI-MMPi: (s)-2-(4-bromo-biphenyl-4-sulfonylamino)-3-methyl-butyric acid (PD200126), 7.5 mg/day/p.o., n = 64] or untreated (MI-only, n = 67). Unoperated mice (n = 16) served as controls. The median survival in the MI-only group was 5 days, whereas median survival was significantly greater in the MI-MMPi group at 38 days (p < 0.05). However, with prolonged MMPi (>120 days), a significant divergence in the survival curves occurred in which significantly greater mortality was observed with prolonged MMPi (p < 0.05). LV echocardiography at 6 months revealed LV dilation in the MI-only and MI-MMPi groups (154 +/- 14 and 219 +/- 24 microl) compared with control (67 +/- 4 microl, p < 0.05), with a greater degree of dilation in the MI-MMPi group (p < 0.05). MMPi conferred a beneficial effect on survival early post-MI, but prolonged MMPi (>3 months) was associated with higher mortality and adverse LV remodeling. These unique results suggest that an optimal temporal window exists with respect to pharmacological interruption of MMP activity in the post-MI period.

Mechanism of transepithelial elimination of elastic fibers in keratoacanthoma

Transepithelial elimination of elastic fibers is frequently seen in keratoacanthoma. However, the mechanism underlying this elastic fiber transport is not yet fully understood. We investigated the process by comparing the related features of 27 cases of keratoacanthoma, eight cases of squamous cell carcinoma and 11 cases of seborrheic keratosis (control). Microscopically, transepithelial elimination of elastic fibers was specifically observed in keratoacanthomas. Elastic fibers were surrounded by keratoacanthoma cell membrane and were ultrastructurally associated with hemidesmosomes and the basement membrane. Collagen fibrils were also observed within small, membrane-delineated vesicles within cells in the lower layers of the tumor. Also noted was strong expression of matrix metalloproteinase-1, which was detected by immunohistochemical analysis and in situ hybridization. Western blotting showed significantly stronger labeling of matrix metalloproteinase-1 in samples of keratoacanthoma than in normal epidermis. In contrast, squamous cell carcinomas and seborrheic keratosis exhibited none of the aforementioned characteristics. We propose that keratoacanthoma cells entrap, lift and eliminate elastic fibers as they proliferate and keratinize toward the epidermal surface, while simultaneously phagocytosing collagen fibrils. In that regard, matrix metalloproteinase-1 appears to play a key role in the degradation of collagen fibrils.

A structural model that explains the effects of hyperglycemia on collagenolysis

Prior investigations into the effects hyperglycemia on collagen degradation have yielded conflicting results. We present a new formalism for understanding the biochemistry of collagenolysis and the effects of hyperglycemia on collagen degradation. The analysis is based on an understanding of environments that affect the conformational stability of collagen. We suggest that collagen can exist in two distinct conformational states-a native state and a vulnerable state. Vulnerable collagen corresponds to a non-native conformation where partially unfolded regions near collagenase cleavage sites enable collagenases to efficiently degrade collagen. Theoretical calculations on collagen-like model peptides suggest that relatively short periods of hyperglycemia can alter the equilibrium distribution of states to favor vulnerable states of collagen. These data provide new insights into the mechanism of collagenolysis and resolve apparently discrepant experimental data on the effects of hyperglycemia on collagen degradation.

C-reactive protein is associated with arterial stiffness in apparently healthy individuals

OBJECTIVE

C-reactive protein (CRP) levels predict outcome in healthy individuals and patients with atherosclerosis. Arterial stiffness also independently predicts all-cause and cardiovascular mortality and may be involved in the process of atherosclerosis. The aim of this study was to investigate the relationship between stiffness and inflammation in a cohort of healthy individuals.

METHODS AND RESULTS

Pulse wave velocity (PWV) and blood pressure were assessed in 427 individuals. Subjects with cardiovascular disease, diabetes, hypercholesterolemia and those using medication were excluded. CRP correlated with age, mean arterial pressure (MAP), brachial and aortic PWV, and pulse pressures. In multiple regression models, aortic PWV correlated independently with age, CRP, male gender, and MAP (R2=0.593; P<0.001). CRP was also independently associated with brachial PWV. Aortic augmentation index correlated with age, gender, MAP, and inversely with heart rate and height, but not with CRP (R2=0.794; P<0.001). Aortic, carotid, and brachial pulse pressures were also independently associated with CRP levels.

CONCLUSIONS

Aortic and brachial PWV, and pulse pressure, relate to levels of inflammation in healthy individuals, suggesting that inflammation may be involved in arterial stiffening. Anti-inflammatory strategies may, therefore, be of benefit in reducing arterial stiffness and thus cardiovascular risk, especially in patients with premature arterial stiffening.

Extracellular matrix molecules in chronic obstructive sialadenitis: an immunocytochemical and Western blot investigation

The exact pathomechanism of inflammation progress and fibrosis in chronic sialadenitis is unknown. Connective tissue growth factor (CTGF), matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been implicated in the pathogenesis of various fibrotic conditions. These factors are thought to be essential in the regulation of extracellular matrix turnover and the development of tissue fibrosis. In the present study, the expression of CTGF, MMP-2, -3, -9, -13 and TIMP-3 was examined in chronic obstructive sialadenitis. Tissue samples of 13 patients with chronic sialadenitis of the submandibular gland associated with sialolithiasis and 4 normal tissue samples of the submandibular gland were analyzed immunohistochemically and by Western blot analysis. An intense CTGF immunoreactivity was observed in the ductal system of inflamed salivary glands, whereas in normal glands no reactivity or a very low CTGF immunoreactivity was present. Immunohistochemical studies revealed a low to strong reactivity of MMP-2, -3, -9, -13, and TIMP-3 in the ductal system, in acinar cells and in lymphomonocytic infiltrates in normal and inflamed tissues. The expression of MMP-2, -3, -9, -13, and TIMP-3 was confirmed by Western blotting in all cases. Over-expression of CTGF in chronic obstructive sialadenitis suggests that this factor may play a role in glandular fibrosis. However, the physiological role of MMP-2, -3, -9, -13, and TIMP-3 in normal glands, as well as their possible role in inflammation progress and fibrosis in chronic obstructive sialadenitis, remains to be elucidated.

Matrix metalloproteinase-2 and -9 involvement in canine tumors

Matrix metalloproteinases (MMPs) are a family of enzymes implicated in the degradation and remodeling of extracellular matrix and in vascularization. They are also involved in pathologic processes such as tumor invasion and metastasis in experimental cancer models and in human malignancies. We used gelatin zymography and immunohistochemistry to determine whether MMP-2 and MMP-9 are present in canine tumors and normal tissues and whether MMP production correlates with clinicopathologic parameters of prognostic importance. High levels of pro-MMP-9, pro-MMP-2, and active MMP-2 were detected in most canine tumors. Significantly higher MMP levels were measured in canine tumors than in nontumors, malignancies had higher MMP levels than benign tumors, and sarcomas had higher active MMP-2 than carcinomas. Cartilaginous tumors produced higher MMP levels than did nonsarcomatous malignancies, benign tumors, and normal tissues, and significantly greater MMP-2 than osteosarcomas and fibrosarcomas. Pro-MMP-9 production correlated with the histologic grade of osteosarcomas. The 62-kd form of active MMP-2 was detected only in high-grade, p53-positive, metastatic malignancies. Zymography proved to be a sensitive and quantitative technique for the assessment of MMP presence but has the limitation of requiring fresh tissue; immunohistochemistry is qualitative and comparatively insensitive but could be of value in archival studies. MMP presence was shown in a range of canine tumors, and their link to tumor type and grade was demonstrated for the first time. This study will allow a substantially improved evaluation of veterinary cancer patients and provides baseline information necessary for the design of clinical trials targeting MMPs.

Matrix metalloproteinases and their tissue inhibitors in the lesions of cardiac and pulmonary sarcoidosis: an immunohistochemical study

The pathogenesis of the tissue damage and fibrosis in sarcoidosis is poorly understood. The matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) must be considered in this regard, because they control the lysis of connective tissue components. Immunohistochemical studies (peroxidase and dual labeling for confocal microscopy) of reactivity for MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, and the 4 membrane-type-MMPs were made on tissues from patients with cardiac (n = 4) and pulmonary (n = 5) sarcoidosis. The granulomas were histochemically similar in both organs. The multinucleated giant cells (MGCs) showed moderate reactivity for MMP-1 and MMP-9 and variable reactivity for MMP-2 and MMP-3; in addition, they showed colocalization of MT-1-MMP, which activates MMP-2. The reactivity of epithelioid cells (ECs) was moderate for MMP-2 and mild for other MMPs. Macrophages showed weaker reactivity for MMPs than did MGCs and ECs. All 3 types of cells showed very low reactivity for TIMPs. Staining for type IV collagen showed focal damage to the basement membranes of cardiac myocytes and pulmonary alveoli near the granulomas. The cells in sarcoid granulomas contain an abundance of MMPs and a paucity of TIMPs. The MGCs also contain MT-1-MMP and thus can activate MMP-2 in the granulomas. The MMPs can cause damage to adjacent cardiac myocytes and pulmonary alveoli, leading to the interstitial fibrosis produced by sarcoidosis.

Expression of matrix metalloproteinases in articular cartilage of temporomandibular and knee joints of mice during growth, maturation, and aging

OBJECTIVE

This study examined the involvement of different matrix metalloproteinases (MMPs) in articular cartilage in the process of growth, maturation, and aging of mice, and compared the temporal changes in the expression of MMPs between temporomandibular joints (TMJ) and knee joints.

METHODS

Homogenates of intact tibial plateau, femoral condyle, and TMJ condyle cartilages from animals of different ages were assessed for gelatinase (MMP-2 and MMP-9) activity by zymography. The messenger RNA (mRNA) expression of MMPs 1, 2, 3, 9, and 13 in tibial plateau cartilage was determined by semiquantitative reverse transcription-polymerase chain reaction, and immunohistochemistry was used to localize MMPs 2, 3, 9, and 13 in the knee joints and TMJ from mice of different ages.

RESULTS

The pattern of gelatinase (MMP-2 and MMP-9) activity and their protein expression as well as that of MMPs 3 and 13 varied with the age of the mouse, and differences in expression were observed between the knee and TMJ cartilage. The expression of mRNA for the MMPs in the tibial plateau was also age related.

CONCLUSION

This study demonstrated changes in the protein and mRNA expression of MMPs 2, 9, 3, and 13 during growth, maturation, and aging in mice. The temporal changes were characteristic of the joint, and distinct differences were observed between the TMJ and knee cartilage. The differences in temporospatial expression of MMPs between the knee joint and TMJ may be the result of differences in load and function of these joints. The information provided in this study contributes to a better understanding of the role of these MMPs in the maintenance and integrity of cartilage tissue.

Immunohistochemical analysis of matrix metalloproteinase-1, -3, and -13 in naturally occurring cartilaginous tumors of dogs

OBJECTIVE

To determine immunoreactivity of matrix metalloproteinase (MMP)-1, -3, and -13 in cartilaginous tumors of dogs, correlate expression of MMP with histologic grade of tumors and clinical outcome of dogs, and compare MMP immunoreactivity between chondrosarcomas and chondromas.

SAMPLE POPULATION

Formalin-fixed, paraffin-embedded tissues obtained from samples of naturally occurring chondrosarcomas (n = 31) and chondromas (8) of dogs that were submitted to our veterinary medical diagnostic laboratory.

PROCEDURE

Histologic sections from each sample were stained with H&E and monoclonal antibody to MMP-1, -3, and -13 by use of an avidin-peroxidase immunohistochemical technique. For each section, histologic grade (I, II, or III) and immunohistochemical expression (0, 1, 2, or 3) were evaluated. Clinical outcome was obtained from medical records or interviews with referring veterinarians and scored as a good outcome, moderate outcome, or poor outcome. Correlations among variables and differences between chondrosarcomas and chondromas were analyzed.

RESULTS

Samples from chondrosarcomas had significantly higher immunoreactivity of MMP-1 and -13, compared with immunoreactivity in samples from chondromas. In chondrosarcomas, a significant positive correlation (r, 0.386) was found between MMP-1 and -13 immunoreactivities, and a significant negative correlation (r, -0.390) was detected between MMP-3 and -13 immunoreactivities.

CONCLUSIONS AND CLINICAL RELEVANCE

A significant increase in expression of collagenases (MMP-1 and -13) in chondrosarcomas, compared with expression in chondromas, suggests that collagenases may play an important role in tumor progression, and possibly metastasis, in chondrosarcomas of dogs.

Pharmacology of acute lung injury

The acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a clinical syndrome that affects both medical and surgical patients. To date, despite improved understanding of the pathogenesis of ALI/ARDS, pharmacological modalities have been unsuccessful in decreasing mortality. However, several pharmacological agents for ARDS are in development and have shown great promise. In addition to the anti-inflammatory category including late corticosteroids, inhaled nitric oxide, alveolar surfactant, and vasodilators are being evaluated. Replacements of anticoagulation mediators have also suggested beneficial effects on the patient outcome. This article provides an overview of pharmacological treatments of ALI/ARDS.

Localized unfolding of collagen explains collagenase cleavage near imino-poor sites

Collagenases cleave all three chains of type III collagen at specific sites characterized by a Gly-Leu or a Gly-Ile bond that is upstream from an imino acid-poor region. Molecular dynamics trajectories were used to calculate the free energy of unfolding for collagen-like model peptides. The free energy profiles suggest that such imino-poor regions can adopt a low-energy, partially unfolded state where one of the peptide chains forms a solvent-exposed loop. The results are consistent with a model for collagenase cleavage where partial unfolding of imino-poor regions enables collagenases to gain access to their cleavage sites.

Matrix metalloproteinases: regulation and dysregulation in the failing heart

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes responsible for myocardial extracellular protein degradation. Several MMP species identified within the human myocardium may be dysregulated in congestive heart failure (CHF). For example, MMPs that are expressed at very low levels in normal myocardium, such as collagenase-3 (MMP-13) and the membrane-type-1 MMPs, are substantially upregulated in CHF. However, MMP species are not uniformly increased in patients with end-stage CHF, suggesting that a specific portfolio of MMPs are expressed in the failing myocardium. With the use of animal models of CHF, a mechanistic relationship has been demonstrated with respect to myocardial MMP expression and the left ventricular (LV) remodeling process. The tissue inhibitors of the MMPs (TIMPs) are locally synthesized proteins that bind to active MMPs and thereby regulate net proteolytic activity. However, there does not appear to be a concomitant increase in myocardial TIMPs during the LV remodeling process and progression to CHF. This disparity between MMP and TIMP levels favors a persistent MMP activation state within the myocardium and likely contributes to the LV remodeling process in the setting of developing CHF. The elucidation of upstream signaling mechanisms that contribute to the selective induction of MMP species within the myocardium as well as strategies to normalize the balance between MMPs and TIMPs may yield some therapeutic strategies by which to control myocardial extracellular remodeling and thereby slow the progression of the CHF process.

Matrix metalloproteinases in colorectal cancer

Matrix metalloproteinases (MMPs) appear to play a key role in the development and progression of human malignancies. MMPs mediate the destruction of the extracellular matrix, which is an important early step in tumor invasion and metastasis. Growing evidence suggests that MMPs also have angiogenic activity and participate in the early stages of tumorigenesis and primary tumor growth. Investigations in experimental animal models have confirmed the importance of MMPs in the pathogenesis of colorectal cancer, and studies in humans show a direct association between increased MMP expression and tumor invasiveness, development of metastases, and shortened survival. In this review, the physiologic role of MMPs in normal tissues is examined and data supporting the role of MMPs in the pathogenesis of colorectal cancer are reviewed. The results of clinical trials with MMP inhibitors in colorectal cancer and promising areas for future investigation are also discussed.

Blood specimen collection methods influence the concentration and the diagnostic validity of matrix metalloproteinase 9 in blood

BACKGROUND

Matrix metalloproteinases (MMP) in blood are promising new diagnostic tools. It was shown that the blood sampling process resulted in different blood concentrations of MMPs. To clarify whether the sampling process also influences the diagnostic validity of MMPs, MMP-9 measurements were performed in plasma and serum samples of patients with prostate carcinoma and renal cell cancer.

METHODS

MMP-9 ELISAs were performed in samples of heparin plasma and serum collected in blood tubes with and without clot accelerator. Measurements were undertaken in 78 healthy persons, 33 patients with prostate carcinoma and 33 patients with renal cell carcinoma.

RESULTS

MMP-9 showed higher concentrations in serum samples than in heparin plasma and was about threefold higher in serum samples collected in tubes with clot activator than in native serum samples. Both patient groups had lower MMP-9 concentrations in serum, whereas in plasma, patients with renal cell carcinoma had higher, but patients with prostate cancer unchanged MMP-9 concentrations. 13 of 33 patients with renal cell carcinoma had increased MMP-9 plasma values but no patient had increased serum concentrations.

CONCLUSIONS

To optimise the diagnostic validity of the MMP-9 in blood, measurements should be performed in heparin plasma but not in serum.

The role of matrilysin (MMP-7) in leukaemia cell invasion

The matrix metalloproteinases (MMPs) are important in tumour cell invasion and metastasis in many common cancers. However, relatively few studies have investigated the role of MMPs and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), in leukaemia cell invasion. This study examined two leukaemia cell lines, K562 and HL-60 and showed that the K562 cell line was four times more invasive than the HL-60 cell line. The expression of MMP-2, matrilysin (MMP-7), MMP-9. TIMP-1, TIMP-2 and TIMP-3 was analysed. Both cell lines produced similar amounts of MMP-2, MMP-9 and TIMP-2. The K562 cells expressed more TIMP-1 than the HL-60 cells and neither cell line expressed TIMP-3. Interestingly, only the K562 cells expressed matrilysin suggesting a potential role for matrilysin in leukaemia cell invasion. in vitro invasion assays performed in the presence of a matrilysin blocking antibody showed a 40% reduction in invasive ability. This data suggests that matrilysin plays an important role in leukaemia cell invasion.