calcimycin and epigallocatechin-gallate

The cytokine thymic stromal lymphopoietin (TSLP) has been implicated in the development and progression of allergic diseases such as atopic dermatitis, asthma, and chronic obstructive pulmonary disease. However, it has not yet been clarified the effect of epigallocatechin-3-O-gallate (EGCG) on the production of TSLP. Thus, we investigated how EGCG inhibits the production of TSLP in the human mast cell line (HMC-1) cells. Enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, luciferase assay, and Western blot analysis were used to investigate the effects of EGCG. EGCG inhibited the production and mRNA expression of TSLP in HMC-1 cells. EGCG also inhibited the nuclear factor-κB luciferase activity induced by phorbol myristate acetate plus A23187. Furthermore, EGCG inhibited the activation of caspase-1 in HMC-1 cells. These results provide evidence that EGCG can help us to treat inflammatory and atopic diseases through the inhibition of TSLP.

Topics: Blotting, Western; Calcimycin; Caspase Inhibitors; Caspases; Catechin; Cell Line; Cytokines; Gene Expression; Genes, Reporter; Humans; Luciferases; Mast Cells; NF-kappa B; Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Tetradecanoylphorbol Acetate; Thymic Stromal Lymphopoietin

Epigallocatechin-3-gallate (EGCG) is a major form of tea catechin and has a variety of biological activities. In the present study, we investigated the effect of EGCG on the secretion of TNF-alpha, IL-6 and IL-8, as well as its possible mechanism of action by using the human mast cell line (HMC-1).. EGCG was treated before the activation of HMC-1 cells with phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore (A23187). To investigate the effect of EGCG on PMA+A23187-stimulated HMC-1 cells, ELISA, Western blot analysis, electrophorectic mobility shift assay and luciferase assay were used in this study.. EGCG (100 microM) inhibited PMA+A23187-induced TNF-alpha, IL-6 and IL-8 expression and production. EGCG inhibited the intracellular Ca(2+) level. EGCG attenuated PMA+A23187-induced NF-kappaB and extracellular signal-regulated kinase (ERK1/2) activation, but not that of c-Jun N-terminal kinase or p38 mitogen-activated protein kinase.. EGCG inhibited the production of TNF-alpha, IL-6 and IL-8 through the inhibition of the intracellular Ca(2+) level, and of ERK1/2 and NF-kappaB activation. These results indicate that EGCG may be helpful in regulating mast-cell-mediated allergic inflammatory response.

Topics: Calcimycin; Calcium; Catechin; Cell Line, Tumor; Extracellular Signal-Regulated MAP Kinases; Humans; Interleukin-6; Interleukin-8; Ionophores; NF-kappa B; RNA, Messenger; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

Recently, we have reported that (-)-epigallocatechin-3-O-gallate (EGCG) acts as an inhibitor of degranulation. However, the inhibitory mechanism for degranulation is still poorly understood. Here we show that suppression of exocytosis-related myosin II regulatory light chain phosphorylation and alteration of actin remodeling are involved in the inhibitory effect of EGCG on the calcium ionophore-induced degranulation from human basophilic KU812 cells. Surface plasmon resonance assay also revealed that EGCG binds to the cell surface, and the disruption of lipid rafts resulted in reduction of EGCG's ability. We have previously identified the raft-associated 67kDa laminin receptor (67LR) as an EGCG receptor on the cell surface. Treatment of the cells with anti-67LR antibody or RNA interference-mediated downregulation of 67LR expression abolished the effects of EGCG. These findings suggest that EGCG-induced inhibition of the degranulation includes the primary binding of EGCG to the cell surface 67LR and subsequent modulation of cytoskeleton.

Topics: Basophils; Calcimycin; Catechin; Cell Degranulation; Cell Line, Tumor; Cytoskeleton; Histamine Release; Humans; Membrane Microdomains; Myosin Light Chains; Myosin Type II; Phosphorylation; Receptors, Laminin

The antithrombotic activities and mode of action of green tea catechins (GTC) and (-)-epigallocatechin gallate (EGCG), a major compound of GTC, were investigated. Effects of GTC and EGCG on the murine pulmonary thrombosis in vivo, human platelet aggregation in vitro, and ex vivo, and coagulation parameters were examined. GTC and EGCG prevented death caused by pulmonary thrombosis in mice in vivo in a dose-dependent manner. They significantly prolonged the mouse tail bleeding time of conscious mice. They inhibited adenosine diphosphate- and collagen-induced rat platelet aggregation ex vivo in a dose-dependent manner. GTC and EGCG inhibited ADP-, collagen-, epinephrine-, and calcium ionophore A23187-induced human platelet aggregation in vitro dose dependently. However, they did not change the coagulation parameters such as activated partial thromboplastin time, prothrombin time, and thrombin time using human citrated plasma. These results suggest that GTC and EGCG have the antithrombotic activities and the modes of antithrombotic action may be due to the antiplatelet activities, but not to anticoagulation activities.

Topics: Adenosine Diphosphate; Animals; Aspirin; Bleeding Time; Calcimycin; Calcium; Catechin; Collagen; Epinephrine; Fibrinolytic Agents; Humans; Ion Transport; Ionophores; Male; Mice; Mice, Inbred ICR; Platelet Aggregation; Platelet Aggregation Inhibitors; Pulmonary Embolism; Rats; Rats, Sprague-Dawley; Tea

The effect of tea polyphenols on the release of chemical mediators, histamine and leukotriene B4 (LTB4), from rat peritoneal exudate cells (PEC) was studied. Among polyphenols, (-)-epigallocatechin gallate (EGCG) most strongly inhibited the histamine release from the cells stimulated with a calcium ionophore, A23187 or compound 48/80. Though (+)-catechin (C) and (-)-epicatechin (EC) had no effect, (-)-epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) moderately inhibited the histamine release. Similarly, EGCG, ECG, and EGC inhibited LTB4 release from PEC, whereas C and EC were not effective. The magnitude of the inhibitory effect on the release of these mediators of tea polyphenols was in the order of EGCG > ECG > EGC. These results indicated an important role of the triphenol structure in the inhibitory activity. Therefore, the possible antiallergic effect of tea polyphenols can be expected.

Topics: Animals; Ascitic Fluid; Calcimycin; Catechin; Flavonoids; Histamine Release; Leukotriene B4; Male; p-Methoxy-N-methylphenethylamine; Phenols; Polymers; Rats; Rats, Wistar; Tea