Epigallocatechin-3-gallate binding to MMP-2 inhibits gelatinolytic activity without influencing the attachment to extracellular matrix proteins but enhances MMP-2 binding to TIMP-2

Plant extracts have dual mechanism on the protection against dentine erosion: action on the dentine substrate and modification of the salivary pellicle

To investigate the effect of some polyphenol-rich plant extracts on the protection of dentine against demineralization, both acting on the dentine and on the salivary pellicle. Dentine specimens (n = 180) were randomly distributed into 6 experimental groups (n = 30/group): Control (deionized water), Açaí extract, Blueberry extract, Green tea extract, Grape seed extract, and Sn²⁺/F^- (mouthrinse containing stannous and fluoride). Each group was further divided into two subgroups (n = 15), according to the site of action of the substance: on the dentine surface (D) or on the salivary pellicle (P). The specimens were submitted to 10 cycles: 30 min incubation in human saliva (P) or only in humid chamber (D), 2 min immersion in experimental substances, 60 min of incubation in saliva (P) or not (D), and 1 min erosive challenge. Dentine surface loss (DSL), amount of degraded collagen (dColl) and total calcium release were analyzed. Green tea, Grape seed and Sn²⁺/F^- showed significant protection, with least DSL and dColl. The Sn²⁺/F^- showed better protection on D than on P, whereas Green tea and Grape seed showed a dual mode of action, with good results on D, and even better on P. Sn²⁺/F^- showed the lowest values of calcium release, not differing only from Grape seed. Sn²⁺/F^- is more effective when acting directly on the dentine surface, while Green tea and Grape seed have a dual mode of action: with a positive effect on the dentine surface itself, but an improved efficacy in the presence of the salivary pellicle. We further elucidate the mechanism of action of different active ingredients on dentine erosion, where Sn²⁺/F^- acts better on the dentine surface, but plant extracts have a dual mode of action, acting on the dentine itself as well as on the salivary pellicle, improving the protection against acid demineralization.

Dual protective effect of the association of plant extracts and fluoride against dentine erosion: In the presence and absence of salivary pellicle

OBJECTIVES

To verify the protective effect of plant extracts associated with fluoride against dental erosion of dentine, in the presence and absence of a salivary pellicle.

METHODS

Dentine specimens (n = 270) were randomly distributed into 9 experimental groups (n = 30/group): GT (green tea extract); BE (blueberry extract); GSE (grape seed extract); NaF (sodium fluoride); GT+NaF (green tea extract and NaF); BE+NaF (blueberry extract and NaF); GSE+NaF (grape seed extract and NaF); negative control (deionized water); and a positive control (commercialized mouthrinse containing stannous and fluoride). Each group was further divided into two subgroups (n = 15), according to the presence (P) or absence (NP) of salivary pellicle. The specimens were submitted to 10 cycles: 30 min incubation in human saliva (P) or only in humid chamber (NP), 2 min immersion in experimental solutions, 60 min of incubation in saliva (P) or not (NP), and 1 min erosive challenge. Dentine surface loss (dSL-10 and dSL-total), amount of degraded collagen (dColl) and total calcium release (CaR) were evaluated. Data were analyzed with Kruskal-Wallis, Dunn's and Mann-Whitney U tests (p>0.05).

RESULTS

Overall, the negative control presented the highest values of dSL, dColl and CaR, and the plant extracts showed different degrees of dentine protection. For the subgroup NP, GSE showed the best protection of the extracts, and the presence of fluoride generally further improved the protection for all extracts. For the subgroup P, only BE provided protection, while the presence of fluoride had no impact on dSL and dColl, but lowered CaR. The protection of the positive control was more evident on CaR than on dColl.

CONCLUSION

We can conclude that the plant extracts showed a protective effect against dentine erosion, regardless of the presence of salivary pellicle, and that the fluoride seems to improve their protection.

(-)-Epigallocatechin-3-Gallate Prevents IL-1β-Induced uPAR Expression and Invasiveness via the Suppression of NF-κB and AP-1 in Human Bladder Cancer Cells

(-)-Epigallocatechin-3-O-gallate (EGCG), a primary green tea polyphenol, has powerful iron scavengers, belongs to the family of flavonoids with antioxidant properties, and can be used to prevent cancer. Urokinase-type plasminogen activator receptors (uPARs) are glycosylphosphatidylinositol (GPI)-anchored cell membrane receptors that have crucial roles in cell invasion and metastasis of several cancers including bladder cancer. The mechanism of action of EGCG on uPAR expression has not been reported clearly yet. In this study, we investigated the effect of EGCG on interleukin (IL)-1β-induced cell invasion and uPAR activity in T24 human bladder cancer cells. Interestingly, nuclear factor (NF)-κB and activator protein (AP)-1 transcription factors were critically required for IL-1β-induced high uPAR expression, and EGCG suppressed the transcriptional activity of both the ERK1/2 and JNK signaling pathways with the AP-1 subunit c-Jun. EGCG blocked the IL-1β-stimulated reactive oxygen species (ROS) production, in turn suppressing NF-κB signaling and anti-invasion effects by inhibiting uPAR expression. These results suggest that EGCG may exert at least part of its anticancer effect by controlling uPAR expression through the suppression of ERK1/2, JNK, AP-1, and NF-κB.

A Dentin Biomimetic Remineralization Material with an Ability to Stabilize Collagen

The integrity of collagen matrix structure is a prerequisite for effectively inducing biomimetic remineralization. Repeated low pH stimulation activates matrix metalloproteinases (MMPs) in dental caries. Activated MMPs cause the breakdown of collagen fibrils. Collagen stabilization is a major obstacle to the clinical application of remineralization templates. Here, galardin-loaded poly(amido amine) (PAMAM)-NGV (PAMAM-NGV@galardin, PNG) is constructed to induce collagen stabilization and dentin biomimetic remineralization simultaneously, in order to combat early caries in dentin. PAMAM acts in the role of nucleation template for dentin remineralization, while galardin acts as the role of MMPs inhibitor. NGV peptides modified on the surface of dendrimer core can form small clusters with synergistic movement in short range, and those short-range clusters can form domain areas with different properties on the surface of PAMAM core and restrict the movement of collagen, favoring collagen crosslinking, which can be explained through the computational simulation analysis results. NGV peptides and galardin show a dual collagen-protective effect, laying the foundation for the dentin remineralization effect induced by PAMAM. PNG induces dentin remineralization in an environment with collagenase, meanwhile showsing anti-dentin caries efficacy in vivo. These findings indicate that PNG has great potential to combat early dentin caries for future clinical application.

Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin

Objective

Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin.

Material and Methods

Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm² of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (μTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey’s test (α=0.05).

Results

After 24 hours, there was no significant difference in the μTBS of the groups. After 6 months, the GT group had significantly higher μTBS values.

Conclusion

It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.

Antioxidant and protease-inhibitory potential of extracts from grains of oat

The most of important crops cultivated for production of foods and feeds could be considered as plants possessing nutraceutical or medically interesting compounds, especially if can be eaten without processing. Chemical and biological parameters that were evaluated in 100 oat (Avena sativa L.) genotypes were others than those that are important in food and feed production. Contents of polyphenols and flavonoids, radical scavenging activity (DPPH), and inhibitory activities against five proteases (trypsin, thrombin, urokinase, elastase, cathepsin B) were analyzed in extracts from mature grains. The antioxidant activity (DPPH) correlated to the content of total polyphenols. Only a minority (15 from 100) of analyzed genotypes created separate subgroup with a high content of polyphenols, flavonoids, and high antioxidant activity. The best in these parameters were genotypes CDC-SOL-FI, Saul, and Avesta, respectively. Fifteen other genotypes assembled another minority subgroup (also 15 from 100) on the basis of their high inhibitory activities against tested proteases. The highest trypsin-, urokinase-, and elastase-inhibitory activities were in genotype Racoon, the best in thrombin-, and cathepsin B-inhibitory activities were genotypes Expression and SW Kerstin, respectively. Three oats genotypes – Rhea, AC Percy, and Detvan appeared in both subgroups.

Epigallocatechin gallate attenuates fibroblast proliferation and excessive collagen production by effectively intervening TGF-β1 signalling

Pulmonary fibrosis (PF) poses a huge burden to the patients and society due to lack of an effective treatment drug. Activation of fibrocyte, fibroblast and myofibroblasts are important steps in the development of PF. Targeting this common pathway with natural chemicals may lead to the development of new drug regimens for PF treatment. In this study, PF was induced in male Wistar rats by intratracheal administration of Bleomycin (BLM). Epigallocatechin gallate (EGCG) was administered to one of the groups of rats to test its efficacy against the development of PF. Bleomycin-induction resulted in significant elevation of matrix metalloproteinase (MMP)-2 and -9 expression, increased RNA and protein expression of transforming growth factor (TGF)-β1, Smads and alpha-smooth muscle actin (α-SMA). EGCG treatment normalized the BLM induced aberrations in these rats. The protective role of EGCG was also validated in vitro using the WI-38 fibroblast cell line. TGF-β1 incubated cells exhibited increased fibroblast proliferation and hydroxyproline levels with a concomitant decrease in the expression of MMPs 2 and 9. An increase in protein expression levels of p-Smad, α-SMA and type I collagen (COL1A) was also exhibited by fibroblasts upon TGF-β1 incubation. Simultaneous treatment of EGCG to WI-38 cells significantly decreased these protein expressions alongside normalizing the MMPs expression. The study revealed that EGCG inhibited fibroblast activation and collagen accumulation by inhibiting TGF-β1 signalling and thus can be considered as an effective drug against PF.

Role of Polyphenols and Other Phytochemicals on Molecular Signaling

Optimized nutrition through supplementation of diet with plant derived phytochemicals has attracted significant attention to prevent the onset of many chronic diseases including cardiovascular impairments, cancer, and metabolic disorder. These phytonutrients alone or in combination with others are believed to impart beneficial effects and play pivotal role in metabolic abnormalities such as dyslipidemia, insulin resistance, hypertension, glucose intolerance, systemic inflammation, and oxidative stress. Epidemiological and preclinical studies demonstrated that fruits, vegetables, and beverages rich in carotenoids, isoflavones, phytoestrogens, and phytosterols delay the onset of atherosclerosis or act as a chemoprotective agent by interacting with the underlying pathomechanisms. Phytochemicals exert their beneficial effects either by reducing the circulating levels of cholesterol or by inhibiting lipid oxidation, while others exhibit anti-inflammatory and antiplatelet activities. Additionally, they reduce neointimal thickening by inhibiting proliferation of smooth muscle cells and also improve endothelium dependent vasorelaxation by modulating bioavailability of nitric-oxide and voltage-gated ion channels. However, detailed and profound knowledge on specific molecular targets of each phytochemical is very important to ensure safe use of these active compounds as a therapeutic agent. Thus, this paper reviews the active antioxidative, antiproliferative, anti-inflammatory, or antiangiogenesis role of various phytochemicals for prevention of chronic diseases.

(−)-Epigallocatechin-3-gallate inhibits matrix metalloproteinases in oral ulcers

The overexpression of MMPs results in excessive extracellular matrix degradation and oral ulcer healing delay.

Galloyl moieties enhance the dentin biomodification potential of plant-derived catechins

Proanthocyanidin-rich plant-derived agents have been shown to enhance dentin biomechanical properties and resistance to collagenase degradation. This study systematically investigated the interaction of chemically well-defined monomeric catechins with dentin extracellular matrix components by evaluating dentin mechanical properties as well as activities of matrix metalloproteinases (MMPs) and cysteine-cathepsins (CTs). Demineralized dentin beams (n=15) were incubated for 1h with 0.65% (+)-catechin (C), (-)-catechin gallate (CG), (-)-gallocatechin gallate (GCG), (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG). The modulus of elasticity (E) and the fold increase in E were determined by comparing specimens at baseline and after treatment. Biodegradation rates were assessed by differences in percentage of dry mass before and after incubation with bacterial collagenase. The inhibition of MMP-9 and CT-B by 0.65, 0.065 and 0.0065% of each catechin was determined using fluorimetric proteolytic assay kits. All monomeric catechins led to a significant increase in E. EGCG showed the highest fold increase in E, followed by ECG, CG and GCG. EGCG, ECG, GCG and CG significantly lowered biodegradation rates and inhibited both MMP-9 and CT-B at a concentration of 0.65%. Overall, the 3-O-galloylated monomeric catechins are clearly more potent than their non-galloylated analogues in improving dentin mechanical properties, stabilizing collagen against proteolytic degradation, and inhibiting the activity of MMPs and CTs. The results indicate that galloylation is a key pharmacophore in the monomeric and likely also in the oligomeric proanthocyanidins that exhibit high cross-linking potential for dentin extracellular matrix.

Nutraceuticals: potential for chondroprotection and molecular targeting of osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease and a leading cause of adult disability. There is no cure for OA, and no effective treatments which arrest or slow its progression. Current pharmacologic treatments such as analgesics may improve pain relief but do not alter OA disease progression. Prolonged consumption of these drugs can result in severe adverse effects. Given the nature of OA, life-long treatment will likely be required to arrest or slow its progression. Consequently, there is an urgent need for OA disease-modifying therapies which also improve symptoms and are safe for clinical use over long periods of time. Nutraceuticals-food or food products that provide medical or health benefits, including the prevention and/or treatment of a disease-offer not only favorable safety profiles, but may exert disease- and symptom-modification effects in OA. Forty-seven percent of OA patients use alternative medications, including nutraceuticals. This review will overview the efficacy and mechanism of action of commonly used nutraceuticals, discuss recent experimental and clinical data on the effects of select nutraceuticals, such as phytoflavonoids, polyphenols, and bioflavonoids on OA, and highlight their known molecular actions and limitations of their current use. We will conclude with a proposed novel nutraceutical-based molecular targeting strategy for chondroprotection and OA treatment.

Mitogenesis of vascular smooth muscle cell stimulated by platelet-derived growth factor-bb is inhibited by blocking of intracellular signaling by epigallocatechin-3-O-gallate

Epigallocatechin gallate (EGCG) is known to exhibit antioxidant, antiproliferative, and antithrombogenic effects and reduce the risk of cardiovascular diseases. Key events in the development of cardiovascular disease are hypertrophy and hyperplasia according to vascular smooth muscle cell proliferation. In this study, we investigated whether EGCG can interfere with PDGF-bb stimulated proliferation, cell cycle distribution, and the gelatinolytic activity of MMP and signal transduction pathways on RAOSMC when it was treated in two different ways-cotreatment with PDGF-bb and pretreatment of EGCG before addition of PDGF-bb. Both cotreated and pretreated EGCG significantly inhibited PDGF-bb induced proliferation, cell cycle progression of the G0/G1 phase, and the gelatinolytic activity of MMP-2/9 on RAOSMC. Also, EGCG blocked PDGF receptor-β (PDGFR-β) phosphorylation on PDGF-bb stimulated RAOSMC under pretreatment with cells as well as cotreatment with PDGF-bb. The downstream signal transduction pathways of PDGFR-β, including p42/44 MAPK, p38 MAPK, and Akt phosphorylation, were also inhibited by EGCG in a pattern similar to PDGFR-β phosphorylation. These findings suggest that EGCG can inhibit PDGF-bb stimulated mitogenesis by indirectly and directly interrupting PDGF-bb signals and blocking the signaling pathway via PDGFR-β phosphorylation. Furthermore, EGCG may be used for treatment and prevention of cardiovascular disease through blocking of PDGF-bb signaling.

Procyanidins from evening primrose (Oenothera paradoxa) defatted seeds inhibit invasiveness of breast cancer cells and modulate the expression of selected genes involved in angiogenesis, metastasis, and apoptosis

There is a growing interest in plant polyphenols (including flavanols) that exhibit pleiotropic biological activities such as antiinflammatory, antioxidant, and anticancer effects. Here, we report for the first time the inhibition of MDA-MB-231 breast cancer cell viability and invasiveness by an evening primrose flavanol preparation (EPFP). We observed a decrease in MDA-MB-231 viability of 50% vs. a control after 72 h of incubation with EPFP at a concentration of 58 μM gallic acid equivalents (GAE) and an inhibition of their invasiveness of 65% vs. a control at 75 μM GAE after 48 h of incubation. EPFP caused a 10-fold reduction in matrix metalloproteinase-9 (MMP-9) activity at 100 μM GAE. Furthermore, through modulation of mRNA expression, EPFP reduced the expression levels of the following proteins: antiapoptotic Bcl-2, angiogenic vascular endothelial growth factor (VEGF), and 2 transcription factors (c-Jun, c-Fos). Moreover, analysis by flow cytometry revealed that EPFP induced apoptosis in MDA-MB-231 cells. In conclusion, our data shows that EPFP inhibits cell viability by increasing apoptosis and decreases cell invasiveness by decreasing angiogenesis.

Saliva and dental erosion

Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear.

OBJECTIVE

This review discusses the role of salivary factors on the development of dental erosion.

MATERIAL AND METHODS

A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party.

RESULTS

Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion.

CONCLUSIONS

Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Targeting the T-cell membrane type-1 matrix metalloproteinase-CD44 axis in a transferred type 1 diabetes model in NOD mice

This study tested the hypothesis that membrane-tethered type-1 matrix metalloproteinase (MT1-MMP)-induced proteolysis of T cell CD44 is important for defining the migration and function of autoreactive T cells, including diabetogenic, insulin-specific and K(d)-restricted IS-CD8(+) cells. To confirm the importance of MT1-MMP proteolysis of CD44 in type 1 diabetes (T1D), the anti-diabetic effects of three MMP inhibitors (3(S)-2,2-dimethyl-4[4-pyridin-4-yloxy-benzenesulfonyl]-thiomorpholine-3-carboxylic acid hydroxamate [AG3340], 2-(4-phenoxyphenylsulfonylmethyl) thiirane [SB-3CT] and epigallocatechin-3-gallate [EGCG]) were compared using an adoptive diabetes transfer model in non-obese diabetic (NOD) mice. Only AG3340 was capable of inhibiting both the activity of MT1-MMP and the shedding of CD44 in T cells; and the transendothelial migration and homing of IS-CD8(+) T cells into the pancreatic islets. SB-3CT and EGCG were incapable of inhibiting T cell MT1-MMP efficiently. As a result, AG3340 alone, but not SB-3CT or EGCG, delayed the onset of transferred diabetes in NOD mice. In summary, the results of the present study emphasize that the MT1-MMP-CD44 axis has a unique involvement in T1D development. Accordingly, we suggest that a potent small-molecule MT1-MMP antagonist is required for the design of novel therapies for T1D.

Green tea may be benefit to the therapy of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. Systemic inflammatory state, oxidative stress injury, and atrial fibrosis are identified as the main mechanisms for AF. Considering the multifactorial mechanisms of AF, a novel therapeutic agent with multi-bioactivities should be presented. Regular consumption of green tea has been associated with a reduced risk of coronary heart disease and against a large number of pathologic conditions. Recent results indicate that green tea extract, especially (-)-epigallocatechin-3-gallate, could effectively decrease inflammatory factors secretion, antagonize oxidation, and inhibit matrix metalloproteinase activities. Inhibition of inflammation, modulation of oxidative stress, and targeting tissue fibrosis represent new approaches in tackling AF; therefore, green tea may be an innovative therapeutic candidate to prevent the occurrence, maintenance, and recurrence of AF.

Green tea polyphenol epigallocatechin-3-gallate: inflammation and arthritis. [corrected]

A number of factors including inflammation and oxidative stress are believed to play a role in the development of chronic joint diseases. Green tea has become a popular drink and is consumed throughout the world. Extracts of green tea and polyphenols present therein have been shown to inhibit the inflammatory responses in vitro in different cell types and the development of arthritis in animal model studies. There is considerable evidence that (-)-epigallocatechin-3-gallate (EGCG), the predominant green tea polyphenol which mimic its effects, inhibits enzyme activities and signal transduction pathways that play important roles in inflammation and joint destruction in arthritis. After oral consumption EGCG become bioavailable and proteomic studies suggest that EGCG may directly interact with a large set of protein targets and alter the physiological response of the cells. Taken together these and other studies identify and support the use of EGCG as a possible chemopreventive agent with a potential to inhibit the development of arthritis. Here we review the biological effects of EGCG in an attempt to understand its pivotal molecular targets that directly affect the inflammation and joint destruction process for prevention and/or for the development of new therapeutics for arthritis in humans.

Possible green tea-induced thrombotic thrombocytopenic purpura

PURPOSE

A case of a patient who developed thrombotic thrombocytopenic purpura (TTP) after consuming a weight-loss product containing green tea is reported.

SUMMARY

A 38-year-old, 68-kg Caucasian woman arrived at the emergency department with a one-week history of malaise, fatigue, and petechiae of the skin. She had no symptoms of infection and denied illegal drug use. Her medical history included hypothyroidism, for which she was treated with levothyroxine 150 microg daily for the past four years. She reported that she had been using a green tea preparation for the two months before admission to lose body weight. The daily preparation contained 200 mg of green tea extract 5:1, equivalent to 1 g of natural green tea. On clinical examination, the patient appeared acutely ill and was afebrile, with pallor, petechiae, and purpura of the extremities. Laboratory test results at the time of admission revealed that the patient had anemia and marked thrombocytopenia. A peripheral blood smear demonstrated a feature of microangiopathic hemolytic anemia. Immunoglobulin G autoantibodies against ADAM metallopeptidase with thrombospondin type 1 motif, 13 were detected. On hospital day 3, the patient appeared confused and exhibited aphasia that was initially transient but then recurrent. Brain computerized tomography did not exhibit focal pathology. Over the next few days, her neurologic symptoms subsided and her platelet count and hematocrit value gradually increased. Plasmapheresis was performed (12 procedures). Corticosteroid treatment was also initiated. After 20 days of hospitalization, the patient was discharged.

CONCLUSION

A 38-year-old woman developed TTP after consuming a weight-loss product containing green tea extract for two months.

Green tea polyphenol (-)-epigallocatechin gallate reduces matrix metalloproteinase-9 activity following transient focal cerebral ischemia

Green tea polyphenol (-)-epigallocatechin gallate (EGCG) has been reported to reduce neuronal damage after cerebral ischemic insult. EGCG is known to reduce matrix metalloproteinase (MMP) activity. MMP can play an important role in the pathophysiology of neurological disorders including cerebral ischemia. The purpose of the current study was to investigate whether EGCG shows an inhibitory effect on MMP activity and neural tissue damage following transient focal cerebral ischemia. In the present study, C57BL/6 mice were subjected to 80 min of focal ischemia induced by middle cerebral artery occlusion (MCAO). Animals were killed 24 h after ischemia. EGCG (50 mg/kg) was administered intraperitoneally immediately after ischemia. Gelatin gel zymography showed an increase in the active form of MMP-9 after ischemia. EGCG reduced ischemia-induced up-regulation of the active form of MMP-9. In in situ zymography, EGCG reduced up-regulation of gelatinase activity induced by cerebral ischemia. Co-incubation with EGCG reduced gelatinase activity directly in postischemic brain section. In 2,3,5-triphenyltetrazolium chloride (TTC) assay, brain infarction was remarkable in the middle cerebral artery territory after focal cerebral ischemia. In EGCG-treated mice, infarct volume was significantly reduced compared with vehicle-treated mice. These results demonstrate that EGCG, a green tea polyphenol, may reduce up-regulation of MMP-9 activity and neuronal damage following transient focal cerebral ischemia. In addition to its antioxidant effect, MMP-9 inhibition might be a possible mechanism potentially involved in the neuroprotective effect of a green tea polyphenol, EGCG.

Activated protein C mediates a healing phenotype in cultured tenocytes

Tendon injuries cause considerable morbidity in the general adult population. The tenocytes within the tendon have the full capacity to heal the tendon intrinsically. Activated protein C (APC) plays an important role in coagulation and inflammation and more recently has been shown to promote cutaneous wound healing. In this study we examined whether APC can induce a wound healing phenotype in tenocytes. Sheep tenocytes were treated with APC, endothelial protein C receptor (EPCR) blocking antibody (RCR252) and/or EPCR small interfering (si)RNA. Cell proliferation and migration were measured by crystal violet assay and a scratch wounding assay, respectively. The expression of EPCR, matrix metalloproteinase (MMP)-2, type I collagen and MAP kinase activity were detected by real time PCR, zymography, immunofluorescence, immunohistochemistry and Western blotting. APC stimulated proliferation, MMP-2 activity and type I collagen deposition in a dose-dependent manner and promoted migration of cultured tenocytes. APC dose-dependently stimulated phosphorylated (P)-ERK2 and inhibited P-p38. Interestingly, tenocytes expressed EPCR protein, which was up-regulated by APC. When tenocytes were pre-treated with RCR252 or EPCR siRNA the effect of APC on proliferation, MMP-2 and type 1 collagen synthesis and MAP kinases was blocked. APC promotes the growth, MMP-2 activity, type I collagen deposition and migration of tenocytes. Furthermore, EPCR is expressed by tenocytes and mediates the actions of APC, at least partly by signalling through selective MAP kinases. These data implicate APC as a potential healing agent for injured tendons.

Regulation of collagen synthesis by inhibitory Smad7 in cardiac myofibroblasts

Transforming growth factor-beta(1) (TGF-beta(1)) signal and downstream Smads play an important role in tissue fibrosis and matrix remodeling in various etiologies of heart failure. Inhibitory Smad7 (I-Smad7) is an inducible regulatory Smad protein that antagonizes TGF-beta(1) signal mediated via direct abrogation of R-Smad phosphorylation. The effect of ectopic I-Smad7 on net collagen production was investigated using hydroxyproline assay. Adenovirus-mediated I-Smad7 gene (at 100 multiplicity of infection) transfer was associated with significant decrease of collagen synthesis in the presence and absence of TGF-beta(1) in primary rat cardiac myofibroblasts. In I-Smad7-infected cells, we also observed the ablation of TGF-beta(1)-induced R-Smad2 phosphorylation vs. LacZ controls. Overdriven I-Smad7 was associated with significantly increased expression of immunoreactive 65-kDa matrix metalloproteinase-2 (MMP-2) protein in culture medium of myofibroblast compared with LacZ-infected cells. Expression of the 72-kDa MMP-2 variant, e.g., the inactive form, was not altered by exogenous I-Smad7 transfection/overexpression. Furthermore, I-Smad7 overexpression was associated with a significant increase and decrease in expression of p27 and phospho-Rb protein, respectively, as well as reduced [(3)H]thymidine incorporation vs. Ad-LacZ-infected controls. We suggest that negative modulation of R-Smad phosphorylation by ectopic I-Smad7 may contribute to the downregulation of collagen in cardiac myofibroblasts and may suppress the proliferation of these cells. Thus treatments targeting the collagen deposition by overexpression of I-Smad7 may provide a new therapeutic strategy for cardiac fibrosis.

Role of green tea polyphenols in the inhibition of collagenolytic activity by collagenase

Inhibitory effect of green tea polyphenols viz., catechin and epigallocatechin gallate (EGCG) on the action of collagenase against collagen has been probed in this study. Catechin and EGCG treated collagen exhibited 56 and 95% resistance, respectively, against collagenolytic hydrolysis by collagenase. Whereas direct interaction of catechin and EGCG with collagenase exhibited 70 and 88% inhibition, respectively, to collagenolytic activity of collagenase against collagen and the inhibition was found to be concentration dependent. The kinetics of inhibition of collagenase by catechin and EGCG has been deduced from the extent of hydrolysis of (2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine), FALGPA. Both catechin and EGCG exhibited competitive mode of inhibition against collagenase. The change in the secondary structure of collagenase on treatment with catechin and EGCG has been monitored using circular dichroism spectropolarimeter. CD spectral studies showed significant changes in the secondary structure of collagenase on treatment with higher concentration of catechin and EGCG. Higher inhibition of EGCG compared to catechin has been attributed to the ability of EGCG to exhibit better hydrogen bonding and hydrophobic interaction with collagenase.

(-)-Epigallocatechin gallate overcomes resistance to etoposide-induced cell death by targeting the molecular chaperone glucose-regulated protein 78

Many beneficial properties have been attributed to (-)-epigallocatechin gallate (EGCG), including chemopreventive, anticarcinogenic, and antioxidant actions. In this study, we investigated the effects of EGCG on the function of glucose-regulated protein 78 (GRP78), which is associated with the multidrug resistance phenotype of many types of cancer cells. Our investigation was directed at elucidating the mechanism of the EGCG and GRP78 interaction and providing evidence about whether EGCG modulates the activity of anticancer drugs through the inhibition of GRP78 function. We found that EGCG directly interacted with GRP78 at the ATP-binding site of protein and regulated its function by competing with ATP binding, resulting in the inhibition of ATPase activity. EGCG binding caused the conversion of GRP78 from its active monomer to the inactive dimer and oligomer forms. Further, we showed that EGCG interfered with the formation of the antiapoptotic GRP78-caspase-7 complex, which resulted in an increased etoposide-induced apoptosis in cancer cells. We also showed that EGCG significantly suppressed the transformed phenotype of breast cancer cells treated with etoposide. Overall, these results strongly suggested that EGCG could prevent the antiapoptotic effect of GRP78, which usually suppresses the caspase-mediated cell death pathways in drug-treated cancer cells, contributing to the development of drug resistance.

Pitavastatin improves cardiac function and survival in association with suppression of the myocardial endothelin system in a rat model of hypertensive heart failure

Statin therapy may be associated with lower mortality in patients with heart failure, but the underlying mechanism of such an association is unknown. We have evaluated the effects of pitavastatin on cardiac function and survival in a rat model of hypertensive heart failure and investigated the molecular mechanism of the observed effects. Dahl salt-sensitive rats fed with high-salt diet from 7 weeks of age developed compensatory left ventricular hypertrophy at 12 weeks and heart failure at 19 weeks. Dahl salt-sensitive rats were treated with either vehicle or pitavastatin (0.3 mg/kg per day) from 7 or 12 weeks. Both early-onset and late-onset pitavastatin treatment reduced left ventricular fibrosis, improved cardiac function, and increased the survival rate apparent at 19 weeks. The increases in the expression levels of hypertrophic, profibrotic, and metalloproteinase genes as well as in gelatinase activities in the heart induced by the high-salt diet were suppressed by pitavastatin treatment. Furthermore, the level of cardiac endothelin-1 was increased in association with the development of heart failure in a manner sensitive to treatment with pitavastatin. Both early and late pitavastatin treatment thus improved cardiac function and survival, with modulation of extracellular matrix remodeling and endothelin-1 signaling possibly contributing to these beneficial effects.

Epigallocatechin-3-gallate protects toluene diisocyanate-induced airway inflammation in a murine model of asthma

Epigallocatechin-3-gallate (EGCG), a major form of tea catechin, has anti-allergic properties. To elucidate the anti-allergic mechanisms of EGCG, we investigated its regulation of matrix metalloproteinase (MMP-9) expression in toluene diisocyanate (TDI)-inhalation lung tissues as well as TNF-alpha and Th2 cytokine (IL-5) production in BAL fluid. Compared with untreated asthmatic mice those administrated with EGCG had significantly reduced asthmatic reaction. Also, increased reactive oxygen species (ROS) generation by TDI inhalation was diminished by administration of EGCG in BAL fluid. These results suggest that EGCG regulates inflammatory cell migration possibly by suppressing MMP-9 production and ROS generation, and indicate that EGCG may be useful as an adjuvant therapy for bronchial asthma.

Intracellular signaling network as a prime chemopreventive target of (–)-epigallocatechin gallate

Chemoprevention is an attempt to use either naturally occurring or synthetic substances or their mixtures to intervene in the progress of carcinogenesis. Recently, it has been shown that some edible phytochemicals alter gene expression, directly or indirectly, thereby regulating the carcinogenic processes. (-)-Epigallocatechin gallate (EGCG), a principal antioxidant derived from green tea, is one of the most extensively investigated chemopreventive phytochemicals. EGCG has been known to block each stage of carcinogenesis by modulating signal transduction pathways involved in cell proliferation, transformation, inflammation, apoptosis, metastasis and invasion. This review addresses the molecular target-based chemoprevention with EGCG by focusing on the common events mediated by transcription factors, such as NF-kappa B, activator protein-1 and nuclear factor erythroid 2 p45-related factor, and upstream kinases involved in the cellular signaling network.

Targeting matrix metalloproteases to improve cutaneous wound healing

Wound repair is a physiological event in which tissue injury initiates a repair process leading to restoration of structure and function of the tissue. Cutaneous wound repair can be divided into a series of overlapping phases including formation of fibrin clot, inflammatory response, granulation tissue formation incorporating re-epithelialisation and angiogenesis and finally, matrix formation and remodelling. Matrix metalloproteases (MMPs) are a family of neutral proteases that play a vital role throughout the entire wound healing process. They regulate inflammation, degrade the extracellular matrix (ECM) to facilitate the migration of cells and remodel the new ECM. However, excessive MMP activity contributes to the development of chronic wounds. Selective control of MMP activity may prove to be a valuable therapeutic approach to promote healing of chronic ulcers. Recent evidence indicates that the anticoagulant, activated protein C may be useful in the treatment of non-healing wounds by preventing excessive protease activity through inhibition of inflammation and selectively increasing MMP-2 activity to enhance angiogenesis and re-epithelialisation.

Inhibition of survival signalling by dietary polyphenols and indole-3-carbinol

Epidemiological studies have long hinted at the possibility that what we eat greatly influences our state of health, in particular our relative risk of developing cancer. In recent years there has been an exponential increase in the number of studies investigating how individual components of the diet interact at the molecular level to determine the fate of a cell. It is now apparent that many such molecules can preferentially inhibit the growth of tumour cells, by inducing cell cycle arrest or apoptosis. The number of signalling pathways and molecular targets involved is continually expanding. Consequently, the picture is becoming ever more complicated, not least because results often appear to be cell-type specific, dose-response relationships are critical, and any one agent appears to have multiple mechanisms of action. In addition most studies have been conducted in cell culture, often with physiologically unachievable concentrations of single agents, making extrapolation to the clinical situation difficult. In this review the mechanisms of action of a few well-studied dietary polyphenols (curcumin, epigallocatechin gallate and resveratrol) and indole-3 carbinol are considered in the light of these issues.

The effects of epigallocatechin-3-gallate on extracellular matrix metabolism

BACKGROUND

Anti-oxidants have attracted a lot of interest on account of their function to protect the skin from oxidative stress by ultraviolet (UV) radiation.

OBJECTIVE

This study examined the effects of epigallocatechin-3-gallate (EGCG), which is a green tea extract, on the extracellular matrix (ECM) changes induced by UV radiation and showed the comparative results with retinoic acid (RA).

METHODS

The ECM metabolism is tightly controlled by the collagen degrading matrix metalloprotienases (MMPs) and their tissue inhibitors (TIMPs). Therefore, the expression of MMPs and TIMP-1 was investigated to evaluate the effects of EGCG and RA. Artificial skin was made using three-dimensionally cultured keratinocytes on a collagen matrix populated with fibroblasts. EGCG and RA were added into the medium of the fibroblasts and keratinocytes culture and also applied topically on artificial skins prior to UVA irradiation. The MMPs and TIMP-1 expression levels were measured using Western blot and a zymogram.

RESULTS

EGCG, like RA, decreased the level of MMPs production and increased TIMP-1 expression level. However, EGCG suppressed the activities of the gelatinases and augmented the expressions of the TIMP-1 more than RA did. RA decreased the MMP-1 and MMP-3 expression levels to a greater extent than EGCG. ECM alterations as a result of UVA appeared to be prevented more effectively using the EGCG treatment.

CONCLUSION

EGCG can reverse the ECM degradation induced by UV even with a topical application of a practical-use concentration. In particular, EGCG proved to be much more effective in ROS-related conditions, such as UVA exposure.

Mechanisms of the inhibitory effect of epigallocatechin-3-gallate on cultured human vascular smooth muscle cell invasion

OBJECTIVE

Although we recently showed that the administration of catechins reduced the neointimal formation in a rat balloon-injury model, the precise molecular mechanisms are largely unknown. In the present study, we tried to determine these mechanisms using an in vitro SMC invasion system.

METHODS AND RESULTS

Boyden chamber assay was used to examine the effect of catechins on the invasive behavior of SMCs. The invasive activity of SMCs through collagen gel was restrained by EGCG in a concentration-dependent manner. The data from gelatin and collagen zymography and Western blot revealed that EGCG blocks the activation of pro-matrix metalloproteinase (MMP)-2 during an invasion assay and in the conditioned medium of cultured SMCs as well as the activities of MMP-2 and membrane type 1-MMP (MT1-MMP) even at 0.1 to 0.3 micromol/L of EGCG. EGCG was found to restrain MT1-MMPcat-dependent pro-MMP-2 activation. EGCG upregulated the expression of tissue inhibitor of MMP-2 (TIMP-2) protein. Reverse zymography showed that the increased TIMP-2 to expression was validated by an increased activity. The data from decreased TIMP-2 activity using its siRNA suggested that upregulation of TIMP-2 expression may be one of the major mechanisms for inhibition of SMC invasion by EGCG.

CONCLUSIONS

These results indicate that EGCG targets multiple MMP-mediated SMC cellular events and provides a new major mechanism for the SMC invasion through upregulation of TIMP-2 expression to modulate MMP activity.

Carnosol inhibits the invasion of B16/F10 mouse melanoma cells by suppressing metalloproteinase-9 through down-regulating nuclear factor-kappaB and c-Jun

Carnosol, a constant constituent of Rosmarinus officinalis extracts, is a phenolic diterpene shown to have antioxidant and anticarcinogen properties. In our studies, carnosol inhibited the invasion of highly metastatic mouse melanoma B16/F10 cells in vitro. First, the antimetastatic potentials of carnosol were examined by soft agar colony formation assay. Second, carnosol dose-dependently inhibited B16/F10 cell migration and invasion by in vitro transwell assay. Third, the decreasing activity of metalloproteinase was observed by zymographic assay. The result revealed that the treatment of carnosol could diminish the activity of MMP-9 more than MMP-2. Next, we analyzed the amounts of MMP-9 and MMP-2 proteins in the cells. The data indicated MMP-9 protein was also suppressed by carnosol in the same manner. In accordance with the above data, the results of reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed a reduced level of MMP-9 mRNA. Furthermore, carnosol significantly inhibited the tyrosine phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, AKT, p38, JNK and inhibition of activation of transcription factors NFkappa-B and c-Jun. These results lead us to conclude that carnosol could restrict the invasive ability of B16/F10 mouse melanoma cells by reducing MMP-9 expression and activity through suppressing (ERK) 1/2, AKT, p38, and JNK signaling pathway and inhibition of NF-kappaB and AP-1 binding activity. Taken together, these results indicate that carnosol targets MMP-mediated cellular events in cancer cells and provides a new mechanism for its anticancer activity.

Prostate carcinoma and green tea: PSA-triggered basement membrane degradation and MMP-2 activation are inhibited by (-)epigallocatechin-3-gallate

Prostate-specific antigen (PSA) is a serine-protease that, in addition to cleaving semenogelins in the seminal coagulum, is able to cleave extracellular matrix glycoproteins, thereby affecting cell migration and metastasis. We here report some new activities of PSA that deserve careful consideration in the cancer context: degradation of gelatin, degradation of type IV collagen in reconstituted basement membrane (Matrigel) and activation of progelatinase A (MMP-2), but not pro-MMP-9, in a cell-free system. Since consumption of green tea has been reported to lower the risk of prostate cancer, we investigated the effects of the major flavanol of green tea, (-)epigallocatechin-3-gallate (EGCG), on expression and activity of PSA by prostate carcinoma cells. In addition to restraint of PSA expression, EGCG was found to inhibit in a dose-dependent manner all the above PSA activities, at concentrations lower than the cytotoxic serine-protease inhibitor PMSF and close to levels measured in the serum following ingestion of green tea. The activity of PSA was suppressed also by the elastase released by the inflammatory leukocytes. These results highlight new PSA activities, suggest gelatin zymography as a new convenient assay for PSA, propose EGCG as natural inhibitor of prostate carcinoma aggressiveness, but also stimulate further investigation on the role of prostatic inflammation.

Role of matrix metalloproteinases in vascular remodeling

Vascular remodeling, defined as lasting structural changes in the vessel wall in response to hemodynamic stimuli, plays a role in many (patho)physiological processes requiring cell migration and degradation of extracellular matrix(ECM). Matrix metalloproteinase(MMP) system can degrade most ECM components. Several lines of evidence support a role for MMP system components in the development and progression of atherosclerosis and restenosis after angioplasty. This review article focuses on the role of MMPs in vascular remodeling relevant to atherosclerosis and restenosis after angioplasty.

Green tea polyphenol epigallocatechin-3-gallate (EGCG) differentially inhibits interleukin-1 beta-induced expression of matrix metalloproteinase-1 and -13 in human chondrocytes

Interleukin-1beta (IL-1beta)-induced inflammatory response in arthritic joints include the enhanced expression and activity of matrix metalloproteinases (MMPs), and their matrix degrading activity contribute to the irreversible loss of cartilage and may also be associated with sustained chronic inflammation. We have earlier shown that green tea (Camellia sinensis) polyphenol epigallocatechin-3-gallate (EGCG) was non-toxic to human chondrocytes [Singh R, Ahmed S, Islam N, Goldberg VM, and Haqqi TM (2002) Arthritis Rheum 46: 2079-2086] and inhibits the expression of inflammatory mediators in arthritic joints [Haqqi TM, Anthony DD, Gupta S, Ahmed N, Lee MS, Kumar GK, and Mukhtar H (1999) Proc Natl Acad Sci USA 96: 4524-4529]. Here we show that EGCG at micromolar concentrations was highly effective in inhibiting the IL-1beta-induced glycosaminoglycan (GAG) release from human cartilage explants in vitro. EGCG also inhibited the IL-1beta-induced mRNA and protein expression of MMP-1 and MMP-13 in human chondrocytes. Importantly, EGCG showed a differential, dose-dependent inhibitory effect on the expression and activity of MMP-13 and MMP-1. A similar differential dose-dependent inhibition of transcription factors NF-kappaB and AP-1 by EGCG was also noted. These results for the first time demonstrate a differential dose-dependent effect of EGCG on the expression and activity of MMPs and on the activities of transcription factors NF-kappaB and AP-1 and provide insights into the molecular basis of the reported anti-inflammatory effects of EGCG. These results also suggest that EGCG or compounds derived from it may be therapeutically effective inhibitors of IL-1beta-induced production of matrix-degrading enzymes in arthritis.