thromboplastin and epigallocatechin-gallate

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic component of green tea. The aim of the current study was to investigate the inhibitory effects of EGCG on anti-β2-glycoprotein I (β2GPI)/β2GPI-induced tissue factor (TF) and tumor necrosis factor-α (TNF-α) expression in the human acute monocytic leukemia cell line, THP-1, as well as the underlying mechanisms. Human THP-1 cells cultured in vitro were treated with lipopolysaccharide (LPS, 500 ng/ml) or with the anti-β2GPI (10 µg/ml)/β2GPI (100 µg/ml) complex following pre-treatment with or without EGCG (0-50 µg/ml). The expression levels of TF, TNF-α and Toll-like receptor 4 (TLR4) were measured, and the activation of mitogen-activated protein kinases (MAPKs) including p38, extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK), and the nuclear factor-κB (NF-κB) signaling pathway was determined by western blot analysis. The results revealed that the anti-β2GPI/β2GPI complex activated the THP-1 cells, resulting in the enhanced expression of the coagulation cytokine, TF, as well as that of the pro-inflammatory cytokine, TNF-α; these levels were almost comparable to those induced by LPS. Pre-treatment with EGCG decreased the TF and TNF-α levels in the THP-1 cells treated with the anti-β2GPI/β2GPI complex in a dose-dependent manner and counteracted the upregulation of TLR4 expression (mRNA and protein) which was induced by the anti-β2GPI/β2GPI complex or LPS. Furthermore, EGCG suppressed the phosphorylation of p38, ERK1/2 and JNK and blocked the activation of the NF-κB signaling pathway induced by the anti-β2GPI/β2GPI complex or LPS. In conclusion, our results indicate that EGCG decreases the anti-β2GPI/β2GPI-induced TF and TNF-α expression in THP-1 cells possibly through the inhibition of the intracellular signal transduction pathway of TLRs-MAPKs-NF-κB axis and may serve as a preventive and therapeutic agent for antiphospholipid syndrome (APS).

Topics: Antibodies; beta 2-Glycoprotein I; Catechin; Cell Line; Enzyme Activation; Humans; MAP Kinase Signaling System; NF-kappa B; RNA, Messenger; Thromboplastin; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Patients with paclitaxel-eluting stents are concerned with stent thrombosis caused by premature discontinuation of dual antiplatelet therapy or clopidogrel resistance. This study investigates the effect of (-)-epigallocatechin-3-gallate (EGCG) on the expression of thrombin/paclitaxel-induced endothelial tissue factor (TF) expressions in human aortic endothelial cells (HAECs). EGCG was nontoxic to HAECs at 6h up to a concentration of 25 micromol/L. At a concentration of 25 micromol/L, EGCG pretreatment potently inhibited both thrombin-stimulated and thrombin/paclitaxel-stimulated endothelial TF protein expression. Thrombin and thrombin/paclitaxel-induced 2.6-fold and 2.9-fold increases in TF activity compared with the control. EGCG pretreatment caused a 29% and 38% decrease in TF activity on thrombin and thrombin/paclitaxel treatment, respectively. Real-time polymerase chain reaction (PCR) showed that thrombin and thrombin/paclitaxel-induced 3.0-fold and 4.6-fold TF mRNA expressions compared with the control. EGCG pretreatment caused an 82% and 72% decrease in TF mRNA expression on thrombin and thrombin/paclitaxel treatment, respectively. The c-Jun terminal NH2 kinase (JNK) inhibitor SP600125 reduced thrombin/paclitaxel-induced TF expression. Furthermore, EGCG significantly inhibited the phosphorylation of JNK to 49% of thrombin/paclitaxel-stimulated HAECs at 60min. Immunofluorescence assay did not show an inhibitory effect of EGCG on P65 NF-kappaB nuclear translocation in the thrombin/paclitaxel-stimulated endothelial cells. In conclusion, EGCG can inhibit TF expression in thrombin/paclitaxel-stimulated endothelial cells via the inhibition of JNK phosphorylation. The unique property of EGCG may be used to develop a new drug-eluting stent by co-coating EGCG and paclitaxel.

Topics: Anthracenes; Catechin; Cells, Cultured; Drug-Eluting Stents; Endothelium, Vascular; Humans; JNK Mitogen-Activated Protein Kinases; Paclitaxel; Phosphorylation; Thrombin; Thromboplastin; Transcription Factor RelA

The effect of epigallocatechin-3-O-gallate (EGCG), a major component of green tea, on platelet preservation was evaluated. Single donor platelets (N = 10) were collected and preserved by the standard method. EGCG was added to the platelet concentrates before preservation and then the functional and biochemical parameters were monitored throughout the storage period. After 6 days of preservation, the aggregability of the platelets was significantly maintained by addition of 50 and 100 microg/ml of EGCG. Platelet prothrombinase activity was also significantly retained by the addition of EGCG. The accumulation of P-selectin and RANTES in the plasma preserved with EGCG was less than those preserved without EGCG, which indicated that EGCG might inhibit platelet activation. Furthermore, EGCG reduced the increase of LDH in plasma during preservation and inhibited the activation of caspase-3 and cleavage of gelsolin, thereby showing that EGCG could inhibit the apoptosis of platelets. These results suggest that EGCG may play an effective role in preserving platelets by inhibiting the activation and apoptosis of platelets.

Topics: Antioxidants; Apoptosis; Blood Platelets; Blood Preservation; Caspase 3; Catechin; Chemokine CCL5; Gelsolin; Humans; L-Lactate Dehydrogenase; P-Selectin; Thromboplastin