Clinical implications of matrix metalloproteinases

Oxidative stress and hepatic stellate cell activation are key events in arsenic induced liver fibrosis in mice

Arsenic is an environmental toxicant and carcinogen. Exposure to arsenic is associated with development of liver fibrosis and portal hypertension through ill defined mechanisms. We evaluated hepatic fibrogenesis after long term arsenic exposure in a murine model. BALB/c mice were exposed to arsenic by daily gavages of 6 μg/gm body weight for 1 year and were evaluated for markers of hepatic oxidative stress and fibrosis, as well as pro-inflammatory, pro-apoptotic and pro-fibrogenic factors at 9 and 12 months. Hepatic NADPH oxidase activity progressively increased in arsenic exposure with concomitant development of hepatic oxidative stress. Hepatic steatosis with occasional collection of mononuclear inflammatory cells and mild portal fibrosis were the predominant liver lesion observed after 9 months of arsenic exposure, while at 12 months, the changes included mild hepatic steatosis, inflammation, necrosis and significant fibrosis in periportal areas. The pathologic changes in the liver were associated with markers of hepatic stellate cells (HSCs) activation, matrix reorganization and fibrosis including α-smooth muscle actin, transforming growth factor-β1, PDGF-Rβ, pro-inflammatory cytokines and enhanced expression of tissue inhibitor of metalloproteinase-1 and pro(α) collagen type I. Moreover, pro-apoptotic protein Bax was dominantly expressed and Bcl-2 was down-regulated along with increased number of TUNEL positive hepatocytes in liver of arsenic exposed mice. Furthermore, HSCs activation due to increased hepatic oxidative stress observed after in vivo arsenic exposure was recapitulated in co-culture model of isolated HSCs and hepatocytes exposed to arsenic. These findings have implications not only for the understanding of the pathology of arsenic related liver fibrosis but also for the design of preventive strategies in chronic arsenicosis.

Interleukin-8 is associated with adhesion, migration and invasion in human gastric cancer SCG-7901 cells

Interleukin-8 is known as an important chemokine involved in tumor angiogenesis and progression. Overexpression of interleukin-8 has been detected in a variety of human tumors, including gastric cancer, and is negatively correlated with prognosis. The aim of our study is to determine the effects of interleukin-8 on proliferation, adhesion, migration and invasion abilities and correlated molecular mechanisms in gastric cancer. We made recombinant interleukin-8 ranged from 0 ng/ml to 100 ng/ml interferes in human gastric cancer SCG-7901 cells in vitro. The results shown that interleukin-8 did not change cell proliferation, but promoted cell adhesion to endothelial cell and extracellular matrix components (collagen, laminin and fibronectin) as detected by Cell Counting Kit-8. And it induced migration and invasion ability based on scratch and transwell-chamber assays. Also, interleukin-8 regulated the protein and mRNA expression of matrix metalloproteinase-9, intercellular adhesion molecule-1 and E-cad and there was obviously a dose-dependent relationship, but the protein or mRNA expression of matrix metalloproteinase-2 was not obviously changed under the tested conditions. Our findings indicate that interleukin-8 is associated with adhesion, migration and invasion in gastric cancer and the regulation of matrix metalloproteinase-9, intercellular adhesion molecule-1 and E-cad expression is one of the potential molecule mechanisms. The studies imply interleukin-8 may be an alternative treatment strategy against gastric cancer.

Comparative analysis of gene expression changes mediated by individual constituents of hemozoin

Plasmodium protozoa, the source of malarial infections, catabolize large quantities of hemoglobin during an intraerythrocytic phase. During this process, free heme is detoxified through biomineralization into an insoluble heme aggregate, hemozoin (Hz). In its native state, Hz is associated with a variety of lipid peroxidation products including 4-hydroxy-2-nonenal (HNE). In the present study, gene expression profiles were used to compare responses to two of the individual components of Hz in a model macrophage cell line. LPS-stimulated RAW 264.7 cells were exposed to HNE and the synthetic form of Hz, beta-hematin (BH), for 6 or 24 h. Microarray analysis identified alterations in gene expression induced by exposure to HNE and opsonized BH (fold change, > or = 1.8; p value, < or = 0.01). Patterns of gene expression were compared to changes induced by an opsonized control latex bead challenge in LPS-stimulated cells and revealed that the BH response was predominantly phagocytic. Ingenuity Pathway Analysis demonstrated that HNE mediated a short-term oxidative stress response and had a prolonged effect on the expression of genes associated with categories of "Cell Cycle", "Cellular Assembly and Organization", "DNA Replication, Recombination, and Repair", and "Cellular Development". Comparisons of expression changes caused by BH and HNE with those observed during malarial infection suggest that BH and HNE are involved in inflammatory response modulation, altered NF-kappaB signal transduction, extracellular matrix (ECM) degradation, and dyserythropoiesis. HNE exposure led to several significant steady-state expression changes including repressed chemokine (C-C motif) ligand 5 (Ccl5), indicative of dyserythropoiesis, and a severe matrix metalloproteinase 9 (Mmp9)/tissue inhibitor of metalloproteinase 1 (Timp1) imbalance in favor of ECM proteolysis.

Inhibitory Effects of Terminalia catappa on UVB-Induced Photodamage in Fibroblast Cell Line

This study investigated whether Terminalia catappa L. hydrophilic extract (TCLW) prevents photoaging in human dermal fibroblasts after exposure to UVB radiation. TCLW exhibited DPPH free radical scavenging activity and protected erythrocytes against AAPH-induced hemolysis. In the gelatin digestion assay, the rates of collagenase inhibition by TCL methanol extract, TCLW, and its hydrolysates were greater than 100% at the concentration of 1 mg/mL. We found that serial dilutions of TCLW (10–500 μg/mL) inhibited collagenase activity in a dose-dependent manner (82.3% to 101.0%). However, TCLW did not significantly inhibit elastase activity. In addition, TCLW inhibited MMP-1 and MMP-9 protein expression at a concentration of 25 μg/mL and inhibited MMP-3 protein expression at a concentration of 50 μg/mL. TCLW also promoted the protein expression of type I procollagen. We also found that TCLW attenuated the expression of MMP-1, -3, and -9 by inhibiting the phosphorylation of ERK, JNK, and p38. These findings suggest that TCLW increases the production of type I procollagen by inhibiting the activity of MMP-1, -3 and -9, and, therefore, has potential use in anti-aging cosmetics.

Immunohistochemical study of matrix metalloproteinases-2 and -9, macrophage inflammatory protein-2 and tissue inhibitors of matrix metalloproteinases-1 and -2 in normal, purulonecrotic and fungal infected equine corneas

OBJECTIVE

Determine the effects of matrix metalloproteinases (MMPs)-2, -9, macrophage inflammatory protein-2 (MIP-2), tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 by immunohistochemical expression in fungal affected and purulonecrotic corneas.

PROCEDURE

Paraffin-embedded equine corneal samples; normal (n = 9), fungal affected (FA; n = 26), and purulonecrotic without fungi (PN; n = 41) were evaluated immunohistochemically for MMP-2, -9, MIP-2, TIMP-1 and -2. The number of immunoreactive inflammatory cells was counted and statistics analyzed. Western blot was performed to detect MMP-2, MMP-9, TIMP-1 and TIMP-2 proteins.

RESULTS

Matrix metalloproteinases-2, -9, MIP-2, TIMP-1 and -2 immunoreactivity was identified in corneal epithelium of normal corneas, and in corneal epithelium, inflammatory cells, keratocytes, and vascular endothelial cells of both FA and PN samples. Inflammatory cell immunoreactivity was significantly higher in FA and PN samples than in the normal corneas. There was positive correlation between MMP-2 and MIP-2, MMP-9 and MIP-2, and MMP-9 and TIMP-1 in inflammatory cell immunoreactivity in FA samples. There was positive correlation between MMP-9 and MIP-2, MMP-9 and TIMP-2, MIP-2 and TIMP-1, and MIP-2 and TIMP-2 in inflammatory cell immunoreactivity in PN samples. Western blot confirmed the presence of all four proteins in equine corneal samples.

CONCLUSION

Increased immunoreactivity of MMP-2 and -9 in FA and PN samples is indirectly related to MIP-2 through its role in neutrophil chemo-attraction. Tissue inhibitors of matrix metalloproteinase-1 and TIMP-2 are up-regulated in equine purulonecrotic and fungal keratitis secondary to MMP-2 and MMP-9 expression. The correlation between MMPs -2 and -9, MIP-2, TIMPs -1 and -2 suggests that these proteins play a specific role in the pathogenesis of equine fungal keratitis.

A disintegrin and metalloproteinase with thrombospondin motifs 9 (ADAMTS9) expression by chondrocytes during endochondral ossification

A disintegrin and metalloproteinase with thrombospondin motifs 9 (ADAMTS9) is known to influence aggrecan degradation in endochondral ossification, but its role has not been well understood. In the present study, in vitro gene expression of ADAMTS9 was investigated by RT-PCR in ATDC5 cells in which experimentally chondrogenic differentiation had been induced. We also investigated the protein localization and gene expression pattern of ADAMTS9 in the tibia growth plate cartilage of male mice in a day 1 neonate, 7-week-old young adult, and a 12-week-old adult by immunohistochemistry and in situ hybridization and compared the results with the expression of proliferating cell nuclear antigen (PCNA) and type X collagen for the identification of proliferative and hypertrophic chondrocyte phenotypes, respectively. We found the gene expression of ADAMTS9 by ATDC5 cells as a dual mode, both before the expression of type X collagen and after hypertrophic differentiation. The immunoreactivity of ADAMTS9 was observed in chondrocytes of proliferative and hypertrophic zones in the growth plate. The population of ADAMTS9 positive cells decreased with age. The results of the present study suggest that ADAMTS9 might have a role in aggrecan cleavage around the chondrocytes to allow chondrocyte proliferation and hypertrophy.

The binding site of zinc and indium metal to amino acid derivatized squarate complexes - Implications in inhibitor and mediator designs

Three novel metal squaric acid-peptide complexes, SQI-SQIII were prepared by addition of indium triflate or zinc chloride to the previously reported compounds [1], 3-(hydroxymethylamino)-4-(l-isoleucine methyl ester)-3-cyclobutene-1,2-dione (squarate 1), and 3-(hydroxymethylamino)-2-(l-isoleucine methyl ester)-4-thioxo-2-cyclobuten-1-one (squarate 2). The structures of SQI-SQIII were elucidated using NMR analysis. The electrochemical applications of two of these metal-squaric acid systems (SQI and SQII) were also investigated. Incorporation of SQII as a mediator, in the previously optimized Pt/p(HEMA)/p(pyrrole)/GOx electrode using the ionic liquid [bmim][BF(4)] as the solvent medium, produced a biosensor with enhanced properties, namely a sensitivity of 175.9mA/M d-glucose, working potential of +200mV, large linear range (0-12mM) and a detection limit of 1x10(-6)M.

Human bone disorders: pathological role and diagnostic potential of matrix metalloproteinases

Bone undergoes continuous remodeling under physiological and pathological conditions. Failure of the regulation of this process leads to several disorders involving bone erosion. This series of events is mainly based on the action of proteinases, particularly matrix metalloproteinases (MMPs). MMPs have been recently suggested as potential bone resorption markers which could be added to the commonly used ones, in order to predict outcome of disease processes and healing, and to monitor disease response to treatment. As for classical biochemical bone markers, MMPs are far from being applied in primary clinical diagnosis, but they could be promising in some cases for disease prognosis. MMPs as bone remodeling biomarkers could provide information that boosts our understanding of the prognosis, disease activity and pathogenesis of bone disorders. Clarifying the MMPs' role in bone remodeling and healing could potentially help predict disease progression and the effects of direct specific therapy.

Down-regulation of the LXR transcriptome provides the requisite cholesterol levels to proliferating hepatocytes

Cholesterol homeostasis is critical for cellular proliferation. Liver X receptor (LXR) alpha and beta are the nuclear receptors responsible for regulation of cholesterol metabolism. In physiological conditions, high intracellular cholesterol levels cause increased synthesis of oxysterols, which activate LXR, thus triggering a transcriptional response for cholesterol secretion and catabolism. Here we employed a mouse model of partial hepatectomy (PH) to dissect the molecular pathways connecting cholesterol homeostasis, cellular proliferation, and LXR. First, we show that hepatic cholesterol content increases after PH, whereas the entire LXR transcriptome is down-regulated. Although LXR messenger RNA (mRNA) levels are unmodified, LXR target genes are significantly down-regulated on day 1 after PH and restored to control levels on day 7, when the liver reaches normal size. The inactivation of LXR following PH is related to the reduced oxysterol availability by way of decreased synthesis, and increased sulfation and secretion. On the contrary, cholesterol synthesis is up-regulated, and extracellular matrix remodeling is enhanced. Second, we show that reactivation of LXR by way of a synthetic ligand determines a negative modulation of hepatocyte proliferation. This effect is sustained by the reactivation of hepatic cholesterol catabolic and secretory pathways, coupled with a significant reduction of cholesterol biosynthesis. Our data unveil a previously unrecognized and apparently paradoxical scenario of LXR modulation. During liver regeneration LXR activity is abated in spite of increasing intracellular cholesterol levels. Turning off LXR-transcriptional pathways is crucial to guaranteeing the requisite intracellular cholesterol levels of regenerating hepatocytes. In line with this hypothesis, pharmacological LXR reactivation during PH significantly reduces liver regeneration capacity.

Role of gap junctions in early brain injury following subarachnoid hemorrhage

Gap junction inhibition has been demonstrated to reverse the vascular contraction that follows experimental subarachnoid hemorrhage. This study hypothesizes that the use of established gap junction inhibitors: octonal and carbenoxolone, to interrupt cell to cell communication will provide neuroprotection against early brain injury after SAH. The filament perforation model of SAH was performed in male Sprague-Dawley rats weighing between 300 and 380 g. Octanol (260.46 mg or 781.38 mg/kg), carbenoxolone (100 mg/kg), or vehicles were given via intraperitoneal injection 1 h after SAH. Neurologic deficits and cerebral apoptosis were assessed 24 and 72 h after SAH. In addition, Western blot analysis was performed to confirm the in vivo inhibition of CNS gap junctions. The administration of octanol and carbenoxolone both failed to attenuate the neurological deficits induced by SAH, and they did not reduce neuronal apoptosis. Additionally, carbenoloxone increased post SAH mortality and exacerbated SAH-induced apoptosis. Despite previous studies that show gap junction inhibitors reverse vasospasm following experimental SAH, they failed to improve clinical outcomes or provide neuroprotection in this study.

Metalloproteinases and their inhibitors-diagnostic and therapeutic opportunities in orthopedics

Matrix metalloproteinases (MMPs) and related enzymes (ADAMs, ADAMTS) and their inhibitors control matrix turnover and function. Recent advances in our understanding of musculoskeletal conditions such as tendinopathy, arthritis, Dupuytren's disease, degenerative disc disease, and bone and soft tissue healing suggest that MMPs have prominant roles. Importantly, MMPs are amenable to inhibition by cheap, safe, and widely available drugs such as the tetracycline antibiotics and the bisphosphonates. This indicates that these MMP inhibitors, if proven effective for any novel indication, may be quickly brought into clinical practice.

Reversal of West Nile virus-induced blood-brain barrier disruption and tight junction proteins degradation by matrix metalloproteinases inhibitor

Though compromised blood-brain barrier (BBB) is a pathological hallmark of WNV-associated neurological sequelae, underlying mechanisms are unclear. We characterized the expression of matrix metalloproteinases (MMP) in WNV-infected human brain microvascular endothelial cells (HBMVE) and human brain cortical astrocytes (HBCA), components of BBB and their role in BBB disruption. Expression of multiple MMPs was significantly induced in WNV-infected HBCA cells. Naïve HBMVE cells incubated with the supernatant from WNV-infected HBCA cells demonstrated loss of tight junction proteins, which were rescued in the presence of MMP inhibitor, GM6001. Further, supernatant from WNV-infected HBCA cells compromised the in vitro BBB model integrity. Our data suggest astrocytes as one of the sources of MMP in the brain, which mediates BBB disruption allowing unrestricted entry of immune cells into the brain, thereby contributing to WNV neuropathogenesis. Because of the unavailability of WNV antivirals and vaccines, use of MMP inhibitors as an adjunct therapy to ameliorate WNV disease progression is warranted.

Testing of the OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage in Rheumatoid Arthritis: A Systematic Literature Search on 5 Candidate Biomarkers

Objective.

To test the OMERACT 8 draft validation criteria for soluble biomarkers by assessing the strength of literature evidence in support of 5 candidate biomarkers.

Methods.

A systematic literature search was conducted on the 5 soluble biomarkers RANKL, osteoprotegerin (OPG), matrix metalloprotease (MMP-3), urine C-telopeptide of types I and II collagen (U-CTX-I and U CTX-II), focusing on the 14 OMERACT 8 criteria. Two electronic voting exercises were conducted to address: (1) strength of evidence for each biomarker as reflecting structural damage according to each individual criterion and the importance of each individual criterion; (2) overall strength of evidence in support of each of the 5 candidate biomarkers as reflecting structural damage endpoints in rheumatoid arthritis (RA) and identification of omissions to the criteria set.

Results.

The search identified 111 articles. The strength of evidence in support of these biomarkers reflecting structural damage was low for all biomarkers and was rated highest for U-CTX-II [score of 6.5 (numerical rating scale 0–10)]. The lowest scores for retention of specific criteria in the draft set went to criteria that refer to the importance of animal studies, correlations with other biomarkers reflecting damage, and an understanding of the metabolism of the biomarker.

Conclusion.

Evidence in support of any of the 5 tested biomarkers (MMP-3, CTX-I, CTX-II, OPG, RANKL) was inadequate to allow their substitution for radiographic endpoints in RA. Three of the criteria in the draft criteria set might not be required, but few omissions were identified.

Oxidative stress promotes the increase of matrix metalloproteinases-2 and -9 activities in the feto-placental unit of diabetic rats

Maternal diabetes increases the risk of congenital malformations, placental dysfunction and diseases in both the neonate and the offspring's later life. Oxidative stress has been involved in the etiology of these abnormalities. Matrix metalloproteases (MMPs), involved in multiple developmental pathways, are increased in the fetus and placenta from diabetic experimental models. As oxidants could be involved in the activation of latent MMPs, we investigated a putative relationship between MMPs activities and oxidative stress in the feto-placental unit of diabetic rats at midgestation. We found that H2O2 enhanced and that superoxide dismutase (SOD) reduced MMPs activities in the maternal side of the placenta and in the fetuses from control and diabetic rats. MMPs were not modified by oxidative status in the fetal side of the placenta. Lipid peroxidation was enhanced in the maternal and fetal sides of the placenta and in the fetus from diabetic rats when compared to controls, and gradually decreased from the maternal placental side to the fetus in diabetic animals. The activities of the antioxidant enzymes SOD and catalase were decreased in the maternal placental side, catalase activity was enhanced in the fetal placental side and both enzymes were increased in the fetuses from diabetic rats when compared to controls. Our data demonstrate changes in the oxidative balance and capability of oxidants to upregulate MMPs activity in the feto-placental unit from diabetic rats, a basis to elucidate links between oxidative stress and alterations in the developmental pathways in which MMPs are involved.

Role of extracellular factors in axon regeneration in the CNS: implications for therapy

The glial scar that forms after an injury to the CNS contains molecules that are inhibitory to axon growth. Understanding of the mechanisms of inhibition has allowed the development of therapeutic strategies aimed at promoting axon regeneration. Promising results have been obtained in animal models, and some therapies are undergoing clinical trials. This offers great hope for achievement of functional recovery after CNS injury.

Gli1 contributes to the invasiveness of pancreatic cancer through matrix metalloproteinase-9 activation

The hedgehog (Hh) signaling pathway has been reported to be associated with the growth of pancreatic cancer, but its role in the invasive phenotype is poorly understood. Therefore, we investigated the role of the Hh pathway in pancreatic cancer cell invasiveness using a Matrigel invasion assay. Blockade of the Hh pathway by cyclopamine inhibited pancreatic cancer cell invasion in association with a decreased expression of matrix metalloproteinase (MMP)-9. By contrast, activation of the Hh pathway by the addition of exogenous Sonic hedgehog increased cell invasion and MMP-9 expression. Stable transfection of pancreatic cancer cells with Gli1 increased their invasiveness, which was associated with activation of MMP-9. We also showed that inhibition of MMP-9 by small interfering RNA blocked the increased invasiveness of Gli1-transfected cells. Furthermore, inhibition of Gli1 by small interfering RNA suppressed the invasiveness and MMP-9 expression of pancreatic cancer cells. Taken together, these findings suggest that members of the Hh pathway, especially Gli1, play an important role in the invasiveness of pancreatic cancer cells through the regulation of MMP-9 expression.

Bone sialoprotein binding to matrix metalloproteinase-2 alters enzyme inhibition kinetics

Bone sialoprotein (BSP) is a secreted glycophosphoprotein normally restricted in expression to skeletal tissue that is also induced by multiple neoplasms in vivo. Previous work has shown that BSP can bind to matrix metalloproteinase-2 (MMP-2). Because of MMP-2 activity in promoting tumor progression, potential therapeutic inhibitors were developed, but clinical trials have been disappointing. The effect of BSP on MMP-2 modulation by inhibitors was determined with purified components and in cell culture. Enzyme inhibition kinetics were studied using a low-molecular weight freely diffusable substrate and purified MMP-2, BSP, and natural (tissue inhibitor of matrix metalloproteinase-2) and synthetic (ilomastat and oleoyl- N-hydroxylamide) inhibitors. We determined parameters of enzyme kinetics by varying substrate concentrations at different fixed inhibitor concentrations added to MMP-2 alone, MMP-2 and BSP, or preformed MMP-2-BSP complexes and solving a general linear mixed inhibition rate equation with a global curve fitting program. Two in vitro angiogenesis model systems employing human umbilical vein endothelial cells (HUVECs) were used to follow BSP modulation of MMP-2 inhibition and tubule formation. The presence of BSP increased the competitive K I values between 15- and 47-fold for natural and synthetic inhibitors. The extent of tubule formation by HUVECs cocultured with dermal fibroblasts was reduced in the presence of inhibitors, while the addition of BSP restored vessel formation. A second HUVEC culture system demonstrated that tubule formation by cells expressing BSP could be inhibited by an activity blocking antibody against MMP-2. BSP modulation of MMP-2 activity and inhibition may define its biological role in promoting tumor progression.

Proteinases in the joint: clinical relevance of proteinases in joint destruction

Proteinases are involved in essential steps in cartilage and bone homeostasis. Consequently, efforts have been made to establish their potential role in the pathology of rheumatic conditions such as rheumatoid arthritis, osteoarthritis and spondyloarthritis. Matrix metalloproteinases (MMPs) are sensitive markers of disease severity and response to treatment, and therefore they have potential in the assessment of rheumatic diseases. Despite disappointing early results with synthetic inhibitors of MMPs, there is still much scope for developing effective and safe MMPs inhibitors, and consequently to deliver new options to inhibit joint destruction.

The clinical significance of acute brain injury in subarachnoid hemorrhage and opportunity for intervention

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating neurological event that accounts for 3-7% of all strokes and carries a mortality rate as high as 40%. Delayed cerebral vasospasm has traditionally been recognized as the most treatable cause of morbidity and mortality from SAH. However, evidence is mounting that the physiological and cellular events of acute brain injury, which occur during the 24-72 h following aneurysm rupture, make significant contributions to patient outcomes, and may even be a more significant factor than delayed cerebral vasospasm. Acute brain injury in aneurysmal SAH is the result of physiological derangements such as increased intracranial pressure and decreased cerebral blood flow that result in global cerebral ischemia, and lead to the acute development of edema, oxidative stress, inflammation, apoptosis, and infarction. The consequence of these events is often death or significant neurological disability. In this study of acute brain injury, we elucidate some of the complex molecular signaling pathways responsible for these poor outcomes. Continued research in this area and the development of therapies to interrupt these cascades should be a major focus in the future as we continue to seek effective therapies for aneurysmal SAH.

Endothelial dependence of matrix metalloproteinase-mediated vascular hyporeactivity caused by lipopolysaccharide

Septic shock remains the leading cause of death in intensive care units in North America. Recent evidence implicates matrix metalloproteinases (MMP) in the pathogenesis of sepsis. MMP activity is upregulated in blood vessels exposed to bacterial lipopolysaccharide (LPS) or pro-inflammatory cytokines and contributes to vascular hyporeactivity to vasoconstrictors. The exact mechanism of MMP-mediated vascular hyporeactivity is unknown. We investigated the contribution of the endothelium in the MMP response to LPS-mediated vascular hyporeactivity in vitro. Tone induced by phenylephrine in isolated rat aortic rings with either intact or denuded endothelium was measured in the presence of LPS for 6 h. These rings were incubated with the nitric oxide (NO) synthase inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME), to determine whether NO synthase was involved in the response, or the MMP inhibitors, doxycycline or GM6001. MMP activity was measured after 6 h. LPS caused a greater reduction of phenylephrine-induced tone in endothelium-intact rings versus endothelium-denuded rings, indicating both endothelium-independent and -dependent mechanisms for LPS-induced vascular hyporeactivity. l-NAME abolished the response to LPS in both endothelium-intact and endothelium-denuded rings. MMP inhibitors prevented the LPS-induced loss of tone in endothelium-intact but not endothelium-denuded rings. LPS caused significantly greater MMP-2 activity in endothelium-intact aortae which was attenuated by doxycycline. MMP-2 activity in endothelium-denuded aortae was unchanged by LPS. The vascular endothelium contributes to MMP-mediated vascular dysfunction induced by LPS. The protective effect of MMP inhibition is endothelium-dependent and is a novel mechanism by which MMPs contribute to vascular dysfunction.

Is metalloproteinase-7 specific for idiopathic pulmonary fibrosis?

BACKGROUND

Matrix metalloproteinase (MMP)-7 was reported to be a key molecule in the pathogenesis of idiopathic pulmonary fibrosis (IPF) based on the result of microarray analysis and knockout mice. However, the role of MMP-7 has not been determined in other types of idiopathic interstitial pneumonia (IIP). The aim of this study was to investigate the role of MMP-7 in IIP by comparing its expression in usual interstitial pneumonia (UIP) and cryptogenic organizing pneumonia (COP).

METHODS

Levels of MMP and tissue inhibitors of metalloproteinase in BAL fluid and their expression on lung tissues were compared between normal control subjects (n = 5) and the patients with IPF (n = 6) and COP (n = 11).

RESULTS

There was no significant difference in BAL fluid MMP-7 levels between UIP and COP, although it was higher in both diseases compared to normal control subjects. Furthermore, the pattern and the degree of MMP-7 expression in lung tissues were also similar in both IPF and COP, whereas MMP-2 level was higher in COP and MMP-9 level was higher in IPF.

CONCLUSION

MMP-7 seems to play an important role in the pathogenesis of not only IPF but also COP; therefore, it may not be the key factor determining the prognosis or reversibility of IIPs.

Inhibitory effect of Uncaria sinensis on human aortic smooth muscle cell migration is based on matrix metalloproteinase-9 inhibitory activity

Medicinal extracts of Cho-Deung-san and Uncaria sinensis Havil. (UR) have previously been shown to have inhibitory effects on migration of vascular smooth muscle cells (VSMC) and matrix metalloproteinase (MMP)-2/9 production, which play key roles in the development of atherosclerosis. In this study, we have more extensively investigated the inhibitory effect of UR on MMP-9 activity and TNF-α induced human aortic smooth muscle cells (HASMC) migration. The result from gelatin zymography showed that UR inhibited MMP-9 activity in a dose-dependent manner (IC(50)=55μg/ml). In addition, UR strongly inhibited the migration of HASMC induced by TNF-α treatment (IC(50)=125μg/ml), although it has very low cytotoxic effect on HASMC (IC(50)>500μg/ml). These results suggest that UR is a potential anti-atherosclerotic agent through inhibition of MMP-9 activity and VSMC migration.

Induction of Smad1 by MT1-MMP contributes to tumor growth

MT1-MMP is a key integral membrane protease, which regulates tumor growth by cleaving extracellular matrix components, activating growth factors and receptors, and consequently, triggering downstream signals. To study what genes or pathways are mediated by endogenous MT1-MMP during tumor growth in vivo, we stably suppressed endogenous MT1-MMP in human tumor cells using RNA interference (RNAi). Tumor growth was significantly reduced in tumors derived from MT1-MMP-suppressed cells relative to control cells; the effect was rescued in cells engineered to re-express MT1-MMP expression. Gene expression profiling of cultured and tumor-derived cells by DNA microarray and real-time RT-PCR revealed that Smad1 expression was upregulated in MT1-MMP-expressing cells and rapidly growing tumors; this was confirmed in 4 additional tumor cell lines. Furthermore, tumor growth of MT1-MMP-expressing cells was reduced when Smad1 was suppressed by RNAi. We also found that the active form, but not the latent form, of TGF-beta was capable in promoting Smad1 expression and 3D cell proliferation in MT1-MMP-suppressed cells. In addition, a dominant-negative form of the TGF-beta Type II receptor reduced Smad1 expression in MT1-MMP-expressing cells. Thus, we propose that MT1-MMP functions, in part, to promote tumor growth by inducing the expression of Smad1 via TGF-beta signaling.

Multiple inflammatory-, tissue remodelling- and fibrosis genes are differentially transcribed in the livers of Abcb4 (-/ - ) mice harbouring chronic cholangitis

OBJECTIVE

Abcb4 (-/-) mice secrete phosphatidylcholine-free, cytotoxic bile and develop chronic cholangitis. The aim of this study was to identify differentially transcribed genes whose products contribute to the liver tissue pathology during this disease.

MATERIAL AND METHODS

Hepatic gene transcription was measured in 3-, 6-, 9- and 20-week-old Abcb4 (-/-) mice (FVB.129P2-abcb4(tm1Bor)/J) using cDNA microarrays, with FVB/NJ Abcb4 (+/+) mice serving as controls. Focus was on inflammatory-, remodelling- and fibrosis genes. Marked differential transcription of inflammatory-, tissue remodelling- and fibrosis genes found by cDNA microarrays was verified by real-time polymerase chain reaction (PCR). Liver pathology was quantified by histopathology scoring.

RESULTS

Transcription of clade A3 Serpin genes showed early, marked down-regulation. The chemokine genes Ccl2, Ccl20 and Cxcl10 were markedly up-regulated. Tissue remodelling- and fibrosis genes exhibiting markedly up-regulated transcription included: Ctgf, Elf3, Lgals3, Mmp12, Mmp15, Spp1, Loxl2, Pdgfa, Pdgfrb, Sparc, Tgfb1, Tgfb2, Tgfbi, Tgfbr2 and Col1a1, Col1a2, Col2a1, Col3a1, Col4a1 genes. Microarray-based recordings of differential gene transcription of the majority of these genes harmonized with the liver histopathology score. Thus, cDNA microarray-based analysis showed increasing differential transcription of several inflammatory-, tissue remodelling- and fibrosis genes during the first 9 weeks of disease and a tendency towards differential transcription to stabilize at an elevated level from 9 to 20 weeks of disease.

CONCLUSIONS

Multiple genes regulating inflammation, tissue remodelling and fibrosis not previously linked to Abcb4 (-/-) cholangitis are identified as being differentially transcribed in Abcb4 (-/-) livers, where they contribute to the pathogenesis of liver tissue pathology.

Regulation of MMP-2 Gene Transcription in Dermal Wounds

Matrix metalloproteinase-2 (MMP-2, gelatinase A) plays an essential role in angiogenesis, inflammation, and fibrosis. These processes are critical for wound healing and accordingly elevated levels of MMP-2 expression have been detected after skin injury. Our goal was to investigate the transcriptional activation of the MMP-2 gene in a model of skin injury by using two different MMP-2/LacZ-reporter mice. Upon skin injury MMP-2 expression was upregulated, whereas tissue from normal skin stained negative except for occasional macrophages, sweat glands, and hair follicles. Skin injury also activated MMP-2 proteolytic activity and reporter gene expression. We demonstrate that MMP-2 regulatory sequences -1686/+423 drive appropriate injury-induced MMP-2-promoter activation. Reporter gene expression was predominantly detectable in endothelial cells and in macrophages. Deletion of the 5' responsive element, denoted RE-1, residing at -1241/+423 bp of the regulatory sequence led to abrogated MMP-2 transcription in vivo. The findings define a crucial role for the enhancer element RE-1 in injury-induced MMP-2 transcription of the skin.

Inhibitor Fingerprinting of Matrix Metalloproteases Using a Combinatorial Peptide Hydroxamate Library

We report the inhibitor fingerprints of seven matrix metalloproteases, representing all five established families of this important class of enzymes, against a highly diversified small-molecule library. A total of 1400 peptide hydroxamates were individually prepared by systematically permuting both natural and unnatural amino acids across the P1', P2', and P3' positions, thereby generating an inhibitor library with three-pronged structural diversity. High-throughput screenings were efficiently conducted in microtiter plate format, providing a rapid and quantitative determination of inhibitor potency across the panel of enzymes. Despite similarities in substrate preferences and structural homologies within this class of enzymes, our findings revealed distinct patterns of inhibition for each MMP against varied chemical scaffolds. The resulting inhibitor fingerprints readily facilitated the identification of inhibitors with good potency as well as desirable selectivity, potentially minimizing adverse effects when developing such leads into candidate drugs. The strategy also offers a novel method for the functional classification of matrix metalloproteases, on the basis of the characteristic profiles obtained using the diverse set of inhibitors. This approach thus paves the way forward in lead identification by providing a rapid and quantitative method for selectivity screening at the outset of the drug discovery process.

Matrix metalloproteinases in peripheral vascular disease

Matrix metalloproteinases (MMPs) are extracellular matrix-modifying enzymes that are important in many physiologic and pathologic vascular processes. Dysregulation of MMP activity has been associated with common vascular diseases such as atherosclerotic plaque formation, abdominal aortic aneurysms, and critical limb ischemia. For this reason, MMPs have become an important focus for basic science studies and clinical investigations by vascular biology researchers. This article reviews the recent literature, summarizing our current understanding of the role of MMPs in the pathogenesis of various peripheral vascular disease states. In addition, the importance of MMPs in the future diagnosis and treatment of peripheral vascular disease is discussed.

Polymeric meshes induce zonal regulation of matrix metalloproteinase‐2 gene expression by macrophages and fibroblasts

Matrix metalloproteinase-2 (MMP-2) is a key regulator in wound healing that orchestrates tissue remodeling. In the present study the spatial and temporal distribution of MMP-2 gene transcription, protein synthesis, and enzymatic activity were analyzed following polymeric mesh (polyglactin, polypropylene) implantation in transgenic reporter mice harboring MMP-2 regulatory sequences -1686/+423 or -1241/+423. Polymers induced MMP-2 promoter activity in macrophages within the foreign body granuloma via sequences -1686/+423 with concomitantly up-regulated protein synthesis and enzymatic activity. Macrophages distant from mesh filaments exhibited low MMP-2 expression levels. Fibroblasts surrounding mesh material displayed strong MMP-2 gene transcription independent of the included promoter sequences, whereas fibroblasts without close contact to mesh material had low MMP-2 synthesis rates due to silencing activity of sequences -1686/-1241. In vitro studies support a cellular crosstalk concept, as macrophages trans-repressed MMP-2 gene transcription in fibroblasts. The zonal and cell-specific regulation of MMP-2 gene transcription illuminates an intimate cellular crosstalk in foreign body reaction that may provide a new approach for mesh modification.

Design and application of an oscillatory compression device for cell constructs

Mechanical compression has been shown to impact cell activity; however a need for a single device to perform a broader range of parametric studies exists. We have developed an oscillatory displacement controlled device to uniaxially strain cell constructs under both static and dynamic compression and used this device to investigate gene expression in cell constructs. The device has a wide stroke (0.25-4 mm) and frequency range (0.1-3 Hz) and several loading waveforms are possible. Alginate cellular constructs with embedded equine chondrocytes were tested and viability was maintained for the 24 h test period. Off-line mechanical testing is described and a modulus value of 18.2 +/- 1.3 kPa found for alginate disks which indicates the level of stress achieved with this deformation profile. Static (15% strain) and dynamic (15% strain, 1 Hz, triangle waveform) testing of chondrocyte constructs was performed and static compression showed significantly higher collagen II expression than dynamic using quantitative RT-PCR. In contrast, differences in matrix metalloproteinase-3 (MMP-3) expression were statistically insignificant. These studies indicate the utility of our device for studying cell activity in response to compression and suggest further studies regarding how the load and strain spectrum impact chondrocyte activity.

Cryptotanshinone from Salvia miltiorrhiza BUNGE has an inhibitory effect on TNF-α-induced matrix metalloproteinase-9 production and HASMC migration via down-regulated NF-κB and AP-1

Matrix metalloproteinases (MMP-9 and MMP-2) production and smooth muscle cell (SMC) migration may play key roles in the phathogenesis of neointima formation and atherosclerosis. Especially inducible MMP-9 expression was directly involved in the cancer cell invasion and SMC migration through vascular wall. In this study, we reveal that cryptotanshinone (CT) purified from Salvia miltiorrhiza BUNGE had an inhibitory effect on MMP-9 production and migration of human aortic smooth muscle cells treated with TNF-alpha in a dose-dependent manner. The down regulation of transcription of MMP-9 mRNA was evidenced by RT-PCR and MMP-9 promoter assay using luciferase reporter gene. Eletrophoretic mobility shift assay showed NF-kappaB and AP-1 nuclear translocations were suppressed. In addition, Western blot analysis indicated that extracellular signal regulated kinase 1 and 2, p38 and JNK MAP kinase signaling pathways were inhibited. From the results, it is suggested that CT has anti-atherosclerosis and anti-neointimal formation activity.

Effect of fibroblast activation protein and alpha2-antiplasmin cleaving enzyme on collagen types I, III, and IV

The circulating enzyme, alpha2-antiplasmin cleaving enzyme (APCE), has very similar sequence homology and proteolytic specificity as fibroblast activation protein (FAP), a membrane-bound proteinase. FAP is expressed on activated fibroblasts associated with rapid tissue growth as in embryogenesis, wound healing, and epithelial-derived malignancies, but not in normal tissues. Its presence on stroma suggests that FAP functions to remodel extracellular matrix (ECM) during neoplastic growth. Precise biologic substrates have not been defined for FAP, although like APCE, it cleaves alpha2-antiplasmin to a derivative more easily cross-linked to fibrin. While FAP has been shown to cleave gelatin, evidence for cleavage of native collagen, the major ECM component, remains indistinct. We examined the potential proteolytic effects of FAP or APCE alone and in concert with selected matrix metalloproteinases (MMPs) on collagens I, III, and IV. SDS-PAGE analyses demonstrated that neither FAP nor APCE cleaves collagen I. Following collagen I cleavage by MMP-1, however, FAP or APCE digested collagen I into smaller peptides. These peptides were analogous to, yet different from, those produced by MMP-9 following MMP-1 cleavage. Amino-terminal sequencing and mass spectrometry analyses of digestion mixtures identified several peptide fragments within the sequences of the two collagen chains. The proteolytic synergy of APCE in the cleavage of collagen I and III was not observed with collagen IV. We conclude that FAP works in synchrony with other proteinases to cleave partially degraded or denatured collagen I and III as ECM is excavated, and that derivative peptides might function to regulate malignant cell growth and motility.

Role of TGF beta-mediated inflammation in cutaneous wound healing

Among many molecules known to influence wound healing, transforming growth factor beta 1 (TGF beta 1) has the broadest spectrum of actions, affecting all cell types that are involved in all stages of wound healing. Both positive and negative effects of TGF beta 1 on wound healing have been reported. However, the underlying mechanisms are largely unknown. We observed that endogenous TGF beta 1 was elevated in a narrow window of time after injury, and transgenic mice constitutively overexpressing wild-type TGF beta 1 in keratinocytes (K5.TGF beta 1wt) exhibited a significant delay in full-thickness wound healing as compared to non-transgenic mice. Delayed wound healing was associated with profound inflammation throughout all stages of wound healing in K5.TGF beta 1wt mice. Our data suggest that excessive and prolonged TGF beta 1 at the wound site does not benefit wound healing, which is partially owing to its pro-inflammatory effect. Future studies need to be conducted to assess whether tightly regulated TGF beta 1 expression will benefit wound healing. To this end, we have developed a gene-switch TGF beta 1 transgenic system that allows TGF beta 1 induction in keratinocytes temporally with desired levels. These mice will provide a tool to study stage-specific effects of TGF beta 1 on cutaneous wound healing.

Synthesis of bicyclic molecular scaffolds (BTAa): An investigation towards new selective MMP-12 inhibitors

Starting from 3-aza-6,8-dioxa-bicyclo[3.2.1]octane scaffold (BTAa) a virtual library of molecules was generated and screened in silico against the crystal structure of the Human Macrophage Metalloelastase (MMP-12). The molecules obtaining high score were synthesized and the affinity for the catalytic domain of MMP-12 was experimentally proved by NMR experiments. A BTAa scaffold 20 having a N-hydroxyurea group in position 3 and a p-phenylbenzylcarboxy amide in position 7 showed a fair inhibition potency (IC50 = 149 microM) for MMP-12 and some selectivity towards five different MMPs. These results, taken together with the X-ray structure of the adduct between MMP-12, the inhibitor 20 and the acetohydroxamic acid (AHA), suggest that bicyclic scaffold derivatives may be exploited for the design of new selective matrix metalloproteinase inhibitors (MMPIs).

Role of matrix metalloproteinase-2 in ethanol-induced invasion by breast cancer cells

Ethanol is a tumor promoter and may enhance the metastasis of breast cancer. However, the underlying cellular/molecular mechanisms remain unknown. Amplification of ErbB2, a receptor tyrosine kinase, is found in 20-30% of breast cancer patients. Ethanol preferably stimulates invasion by breast cancer cells over-expressing ErbB2 in vitro. Over-expression of ErbB2 is positively associated with elevated levels of matrix metalloproteinase-2 (MMP-2) and MMP-9. Ethanol at physiologically relevant concentrations activates MMP-2 without altering its expression level in mammary epithelial cells over-expressing ErbB2, but not in cells expressing low levels of ErbB2. The activation is dependent on c-jun N-terminal kinases (JNK) and reactive oxygen species. Selective inhibitors of MMP-2 and anti-oxidants significantly inhibit ethanol-stimulated cell invasion. Similarly, knocking down MMP-2 by small interference RNA induces a partial blockage on ethanol-promoted cell invasion. Matrix metalloproteinase-2 is predominantly expressed in stromal fibroblasts; ethanol also activates fibroblastic MMP-2. The conditioned medium collected from ethanol-exposed fibroblasts dramatically stimulates the invasion of breast cancer cells. The role of MMP-2 in ethanol-induced tumor promotion is discussed.

Matrix metalloproteinase-9 is an important factor in hepatic regeneration after partial hepatectomy in mice

Partial hepatectomy triggers hepatocyte proliferation, hepatic matrix remodeling, and hepatocyte apoptosis, all of which are important processes in the regenerating liver. Previous studies have shown an increase in the levels of matrix metalloproteinases gelatinase A (MMP-2) and gelatinase B (MMP-9) after partial hepatectomy. The goal of this study was to investigate the role of MMP-9 in liver regeneration after partial hepatectomy. A 70% hepatectomy or sham laparotomy was performed in wild-type or MMP-9-deficient (MMP-9-/-) mice. Hepatic regeneration was determined by liver weight/total body weight ratios and BrdU staining, which was used to a calculate mitotic index at several times postoperatively. Cytokine and growth factor expression was evaluated by Luminex bead-based ELISA and Western blots. Finally, the effect of MMP-9 on apoptosis was measured using TUNEL and caspase expression. The MMP-9-/- animals had a delayed hepatic regenerative response when compared with wild-type controls. The MMP-9-deficient animals expressed significantly less VEGF, HGF, and TNF-alpha between days 2 and 3 post-hepatectomy. Apoptosis, as measured by TUNEL staining and caspase expression, was decreased in the MMP-9-/-. In conclusion, MMP-9 plays an important role in liver regeneration after partial hepatectomy by affecting matrix remodeling, as well as cytokine, growth factor, and caspase expression.

Matrix metalloproteinase-9 and autoimmune diseases

Matrix metalloproteinases (also named matrixin or MMPs) are a major group of enzymes that regulate cell-matrix composition by using zinc for their proteolytic activities. They are essential for various normal biological processes such as embryonic development, morphogenesis, reproduction tissue resorption, and remodeling. Metalloproteinases also play a role in pathological processes including inflammation, arthritis, cardiovascular diseases, pulmonary diseases and cancer. Herein we review the involvement of MMP-9 in a variety of autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, systemic sclerosis, rheumatoid arthritis, multiple sclerosis, polymyositis and atherosclerosis. MMP-9 plays either a primary or secondary role in each one of those autoimmune diseases by its up or down-regulation. It is not expressed constantly but rather is induced or suppressed by many regulating molecules. This feature of MMP-9 along with its involvement in disease pathogenesis turns it into a target for therapy of autoimmune diseases.

Inhibitory effect of Salvia miltiorrhia BGE on matrix metalloproteinase-9 activity and migration of TNF-α-induced human aortic smooth muscle cells

The migration and matrix metalloproteinases (MMPs) production of vascular smooth muscle cells (VSMC) may play a key role in the development of atherosclerosis. The Radix of Salvia miltiorrhiza Bunge (Labiatae) (SM), an eminent herb, is often included as an ingredient in various herbal remedies recommended for vascular therapies and has been used to treat vascular diseases for many centuries. In this study, we investigated the inhibitory effect of SM on TNF-alpha induced human aortic smooth muscle cells (HASMC) migration and MMP-9 activity. Various extracts prepared from stems of SM were tested for cytotoxic activity on HASMC using the XTT assay method. The ethanol extract (IC50 > 100 microg/ml), water extract (IC50 > 100 microg/ml) and chloroform (IC50 = 90 microg/ml) fraction exhibited weak cytotoxic activity. However, buthanol (IC50 = 80 microg/ml) and ethyl acetate (EtOAc; IC50 = 70 microg/ml) fraction exhibited strongly cytotoxic activity. Also, the extracts and fractions were investigated the inhibitory effects on MMP-9 activity using gelatin zymography. Gelatin zymography showed that the TNF-alpha-treated HASMC secreted MMP, probably including MMP-9, which may be involved in HASMC migration. The EtOAc fraction showed stronger inhibitory effect of proteolytic activity than other fractions. The EtOAc fraction was able to decrease the proteolytic activity of MMP-9 in a concentration-dependent manner on zymography. The Matrigel migration assay showed that SM effectively inhibited the TNF-alpha induced migration of HASMC as compared with the control group in a dose-dependent manner (IC50 = 65 microg/ml) and that the EtOAc fraction effectively inhibited the migration of HASMC, as compared with the control group in a dose-dependent manner. These results suggest that SM could be used as potential anti-atherosclerotic agent for anti-migration in TNF-alpha treated HASMC.

In vitro characterization of an in situ microdialysis sampling assay for elastase activity detection

A microdialysis sampling method has been developed to detect the in vitro presence of a proteolytic enzyme, porcine elastase, external to a microdialysis probe. Elastase converts the substrate, succinyl(Ala)(3)-p-nitroanilide (suc(Ala)(3)-p-NA), to p-nitroaniline (p-NA). The substrate, suc(Ala)(3)-p-NA, was locally delivered through the microdialysis probe to external solutions containing different elastase activities (0.025-0.5 units/mL). The product, p-NA, was recovered back into the probe. Dialysates containing both suc(Ala)(3)-p-NA and p-NA were quantified using HPLC-UV. Different microdialysis suc(Ala)(3)-p-NA extraction efficiencies (EE) were observed among different elastase-containing solutions (buffer and 0.3% agar solutions). The p-NA concentrations recovered back into the microdialysis probe correlated with the elastase activity external to the microdialysis probe. The greatest fraction of p-NA recovered as compared to substrate lost occurred with the highest flow rate used (5.0 microL/min). However, the highest concentrations of p-NA recovered occurred at the lowest flow rates. This method may allow for microdialysis sampling to be used as a means to study localized enzyme activity.

Rat gastric gelatinase induction during endotoxemia

Despite continued investigation, the pathogenesis of tissue injury secondary to sepsis remains elusive. Further evaluation of the mechanisms by which endotoxemia and sepsis induce tissue injury is necessary to formulate rational and effective treatment strategies. The purpose of these studies was to evaluate the role of the matrix metalloproteinases MMP-2 and MMP-9 in gastric injury during lipopolysaccharide induced endotoxemia. Lipopolysaccharide increased gastric gelatinase activity as determined by in situ and gelatin zymography. Specifically, lipopolysaccharide induced MMP-2, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) transcription, with subsequent increases in MMP-2 and TIMP-1 protein expression. Furthermore, selective metalloproteinase inhibition ameliorated gastric injury in this model. These data suggest that lipopolysaccharide-induced gastric injury is mediated, at least in part, by increased MMP-2 production.

Effect of different flavonoids on collagen synthesis in human fibroblasts

In this study, we discovered that flavonoids belonging to the subclasses: (flavanone, flavone, and flavonol) display differential effects on the synthesis of collagen in human dermal fibroblasts. At 80 microg/ml flavonoids quercetin-3,3',4', 5,7-pentahydroxyflavone, 3-methyl quercetin, and 7-hydroxyflavone significantly decreased the total protein concentration which was a direct consequence of their cytotoxic effect, while naringenin exhibited no effect on total collagen and total protein concentration. Quercetin-3,3'4',7-tetramethyl ether, 4'-hydroxyflavanone, flavanone, and fisetin significantly decreased collagen concentration while morin, rutin, and chrysin increased collagen concentration without changing the overall protein concentration. The initial screening performed in this study enables the identification of compounds that exert significant effects on fibroblast function and show potential as starting material for pharmaceutical preparations targeted against various disorders centered around disturbed collagen metabolism.

Gene expression profiles reveal increased mClca3 (Gob5) expression and mucin production in a murine model of asbestos-induced fibrogenesis

To elucidate genes important in development or repair of asbestos-induced lung diseases, gene expression was examined in mice after inhalation of chrysotile asbestos for 3, 9, and 40 days. We identified changes in the expression of genes linked to proliferation (cyclin B2, CDC20, and CDC28 protein kinase regulatory subunit 2), inflammation (CCL9, CCL6, complement component 1, chitinase3-like 3, TNF superfamily member 10, and IL-1B), and matrix remodeling (MMP12, MMP3, integrin alphaX, and cathepsins K, Z, B, and S). The most highly induced gene at all time points was mclca3 (gob5), a putative calcium-activated chloride channel involved in the regulation of mucus production and/or secretion. Using histochemistry, we demonstrated accumulation of mucus and increased mClca3 protein in the bronchiolar epithelium of asbestos-exposed mice at all time points but peaking at 9 days. Cytokine levels (interleukin-1beta, interleukin-4, interleukin-6) in bronchoalveolar lavage fluid also increased at 9 days, suggesting Th2-mediated immunity may play a role in asbestos-induced mucus production. In contrast, levels of cathepsin K, a potent elastase, increased between 3 and 40 days at both the mRNA and protein levels, localizing primarily in CD45-positive leukocytes and interstitial cells. Identification of genes involved in lung injury and remodeling after asbestos exposure could aid in defining mechanisms of airborne particulate-induced disease and in developing therapeutic strategies.

Role of an aprotinin-sensitive protease in protein kinase Calpha-mediated activation of cytosolic phospholipase A2 by calcium ionophore (A23187) in pulmonary endothelium

Treatment of bovine pulmonary artery endothelial cells with the calcium ionophore, A23187, stimulates the cell membrane associated protease activity, phospholipase A2 (PLA2) activity, and arachidonic acid (AA) release from the cells. Pretreatment of the cells with arachidonyl-trifluomethylketone (AACOCF3), a cPLA2 inhibitor, but not bromoenollactone (BEL), a iPLA2 inhibitor, prevents A23187 stimulated PLA2 activity and AA release without producing an appreciable alteration of the protease activity. Pretreatment of the cells with aprotinin, an ambient protease inhibitor, prevents the increase in the protease activity and cPLA2 activity in the membrane and AA release from the cells caused by both low and high doses of A23187, and also inhibits protein kinase C (PKC) activity caused by high doses of A23187. Immunoblot study of the endothelial cell membrane isolated from A23187 (10 microM)-treated cells with polyclonal PKCalpha antibody elicited an increase in the 80 kDa immunoreactive protein band along with an additional 47 kDa immunoreactive fragment. Pretreatment of the cells with aprotinin abolished the 47 kDa immunoreactive fragment in the immunoblot. Immunoblot study of the endothelial membrane with polyclonal cPLA2 antibody revealed that treatment of the cells with A23187 dose-dependently increases cPLA2 immunoreactive protein profile in the membrane. It therefore appears from the present study that treatment of the cells with a low dose of A23187 (1 microM) causes a small increase in an aprotinin-sensitive protease activity and that stimulates cPLA2 activity in the cell membrane without an involvement of PKC. By contrast, treatment of the cells with a high dose of 10 microM of A23187 causes optimum increase in the protease activity and that plays an important role in activating PKCalpha, which subsequently stimulates cPLA2 activity in the cell membrane. Although pretreatment of the cells with pertussis toxin caused ADP ribosylation of a 41 kDa protein in the cell membrane, it did not inhibit the cPLA2 activity and AA release caused by both low and high doses of A23187.