Epigallocatechin-3-gallate enhances ischemia/reperfusion-induced apoptosis in human umbilical vein endothelial cells via AKT and MAPK pathways

Deoxynivalenol Induces Apoptosis via FOXO3a-Signaling Pathway in Small-Intestinal Cells in Pig

Deoxynivalenol (DON) is a mycotoxin that is found in feed ingredients derived from grains such as corn and wheat. Consumption of DON-contaminated feed has been shown to cause damage to the intestine, kidneys, and liver. However, the molecular mechanism by which DON exerts its effect in the small intestine is not completely understood. As a result, we profiled gene expression in intestinal epithelial cells treated with DON and examined the molecular function in vitro. We hypothesized that DON could induce apoptosis via the FOXO3a-signaling pathway in intestinal epithelial cells based on these findings. DON induced the apoptosis and the translocation of FOXO3a into the nucleus. Moreover, the inhibiting of FOXO3a alleviated the apoptosis and expression of apoptosis-related genes (TRAL, BCL-6, CASP8, and CASP3). ERK1/2 inhibitor treatment suppressed the translocation of FOXO3a into the nucleus. Our discovery suggests that DON induces apoptosis in intestinal epithelial cells through the FOXO3a-signaling pathway.

Investigation of nickel sulfate-induced cytotoxicity and underlying toxicological mechanisms in human umbilical vein endothelial cells through oxidative stress, inflammation, apoptosis, and MAPK signaling pathways

Growing evidence indicates that nickle and its compounds have adverse effects on the cardiovascular system. In this study, the cytotoxic insults caused by nickel sulfate (NiSO₄ ) in human umbilical vein endothelial cells (HUVECs) were explored by examining cell viability, oxidative stress, inflammation, apoptosis, and MAPK signaling pathway activity. Cultured HUVECs were treated with varying concentrations of NiSO₄ (0, 62.5, 250, and 1000 μM) for 24 h. Subsequently, markers of oxidative stress, inflammation, apoptosis, and MAPK signaling pathways were analyzed using biochemical assays, real-time quantitative polymerase chain reaction, and western blot. Rates of apoptosis were evaluated using flow cytometry. The results showed that NiSO₄ exerted dose- and time-dependent inhibitory effects on cell growth. It induced oxidative stress and lipid peroxidation by increasing the generation of reactive oxygen species, the oxidized glutathione to reduced glutathione ratio (GSSG/GSH ratio), and malondialdehyde levels. Further, it inhibited superoxide dismutase activity in HUVECs. Flow cytometry analysis results revealed that NiSO₄ (62.5-1000 μM) could induce apoptosis in HUVECs. The protein and gene expressions of cleaved Caspase 3 and Bax were elevated, and those of Bcl-2 and Bcl-XL were reduced after NiSO₄ treatment. Additionally, NiSO₄ triggered inflammation in HUVECs, increasing the protein and mRNA levels of IL-6 and TNF-α and reducing those of TGF-β. Furthermore, western blot findings revealed that NiSO₄ could activate MAPK signaling pathways, upregulating p38, JNK, and ERK1/2 in HUVECs by increasing the levels of p-P38，p-JNK, and p-ERK1/2 in a dose-dependent manner. MAPK pathway inhibitors (10 μM SB203580 and 10 μM SP600125) could attenuate the NiSO₄ -induced increase in apoptosis and inflammation in HUVECs. They could also attenuate the dysregulation of inflammatory factors and related proteins caused by high-dose NiSO₄ exposure. Interestingly, while the MEK inhibitor U0126 (10 μM) enhanced NiSO₄ -induced apoptosis in HUVECs, it reduced cell inflammation. Taken together, these experimental results suggest that NiSO₄ can inhibit cell growth, induce oxidative stress, and trigger subsequent inflammatory responses and apoptosis in HUVECs. These effects may be mediated by the P38 and JNK MAPK stress response pathways.

EGCG Regulates Cell Apoptosis of Human Umbilical Vein Endothelial Cells Grown on 316L Stainless Steel for Stent Implantation

Background

Nowadays, medical grade 316L stainless steel (316L SS) is being widely used for intravascular stents, and the drug-eluting stent (DES) system is able to significantly reduce the occurrences of in-stent restenosis. But the drugs and the polymer coating used in DES potentially induce the forming of late stent thrombosis. In order to reduce the occurrence of ISR after stent implantation, the development of novel drugs for DESs is urgently needed.

Methods

This study aimed to investigate the potential mechanisms of epigallocatechin-3-gallate (EGCG) on human umbilical vein endothelial cells (HUVEC) grown on 316L stainless steel (316L SS) using flow cytometry and Q-PCR methods.

Results

Our results showed that EGCG (12.5, 25, 50, 100 μmol/L) significantly inhibited HUVEC proliferation. Flow cytometry analysis indicated that EGCG (25, 50, 100 μmol/L) induced apoptosis. Moreover, qRT-PCRrevealed that genes associated with cell apoptosis (caspase-3, 8, 9, Fas) and autophagy (Atg 5, Atg 7, Atg 12) were up-regulated after EGCG treatment.

Conclusion

These findings indicate that EGCG possesses chemo preventive potential in stent coating which may serve as a novel new drug for stent implantation.

Downregulation of miR-3568 Protects Against Ischemia/Reperfusion-Induced Cardiac Dysfunction in Rats and Apoptosis in H9C2 Cardiomyocytes Through Targeting TRIM62

microRNA-3568 (miR-3568) has been reported to be associated with atherosclerosis. Only few data describe the expression and underlying mechanism of miR-3568 in regulating cardiac ischemia-reperfusion (I/R) injury such as apoptosis. In this study, we therefore sought to investigate the potential function of miR-3568 in simulated I/R-induced apoptosis in H9C2 cardiomyocytes and related signaling pathways involved. Flow cytometry was performed to examine the cell apoptosis. The expression of miR-3568, Survivin, Bcl-2, ERK, JNK, p38, AKT, and STAT3 was measured by western blot and quantitative real-time PCR. The correlation between TRIM62 and p-STAT3 was measured by co-immunoprecipitation and ubiquitination. We found that miR-3568 expression in simulated I/R-induced H9C2 cardiomyocytes was increased in a time-dependent manner. miR-3568 mimic transfection in H9C2 cardiomyocytes significantly enhanced cell apoptosis, decreased the expression of Bcl-2 and Survivin, and activated STAT3 signaling, which were reversed by miR-3568 inhibitor. The direct interaction between miR-3568 and the 3'-untranslated region (UTR) of TRIM62 mRNA was confirmed by dual-luciferase reporter assay. TRIM62 overexpression or AG490, a selective inhibitor of JAK2/STAT3 significantly, significantly inhibited I/R and miR-3568 mimic induced cell apoptosis and STAT3 activation. TRIM62 was found to interact with and induce ubiquitination of p-STAT3. The facilitating role of miR-3568 in I/R injury was also observed in our in vivo rat models. In conclusion, our study suggests that miR-3568 promotes simulated I/R-induced apoptosis in H9C2 cardiomyocytes through targeting TRIM62.

Preclinical Pharmacological Activities of Epigallocatechin-3-gallate in Signaling Pathways: An Update on Cancer

Epigallocatechin gallate (EGCG) is the main bioactive component of catechins predominantly present in svarious types of teas. EGCG is well known for a wide spectrum of biological activity as an anti-oxidative, anti-inflammatory, and anti-tumor agent. The effect of EGCG on cell death mechanisms via the induction of apoptosis, necrosis, and autophagy has been documented. Moreover, its anti-proliferative and chemopreventive action has been demonstrated in many cancer cell lines. It was also involved in the modulation of cyclooxygenase-2, in oxidative stress and inflammation of different cell processes. EGCG has been reported as a promising target for plasma membrane proteins, such as epidermal growth factor receptor (EGFR). In addition, it has been demonstrated a mechanism of action relying on the inhibition of ERK1/2, p38 MAPK, NF-κB, and vascular endothelial growth factor (VEGF). EGCG and its derivatives were used in proteasome inhibition and they were involved in epigenetic mechanisms. In summary, EGCG is the most predominant and bioactive constituent of teas and it has a pivotal role in cancer prevention. Its preclinical pharmacological activities are associated with complex molecular mechanisms that involve numerous signaling pathways.

miRNA-145-5p induces apoptosis after ischemia-reperfusion by targeting dual specificity phosphatase 6

Disorders mainly caused by ischemia-reperfusion (I/R), including stroke and myocardial infarction, is linked to debilitating health conditions and death. Recent research indicates that microRNAs (miRNAs) mediate the process of ischemic pathology. This study investigated the effects of miR-145-5p in regulating myocardial ischemic injury. The I/R models were established in rat cardiomyocytes H9C2 and rats. Western blot analysis and quantitative polymerase chain reaction was performed to analyze protein expression. Annexin V-FITC/PI staining was conducted to evaluate cell apoptosis. The application of miR-145-5p mimics and inhibitor revealed that miR-145-5p promoted apoptosis in cardiomyocytes. Furthermore, we found that miR-145-5p directly inhibited dual specificity phosphatase 6 (DUSP6) by luciferase reporter assay. The results indicated that DUSP6 was beneficial against I/R injury through inhibiting c-Jun N-terminal kinase pathways. In conclusion, the essential roles of miR-145-5p and DUSP6 in I/R provide a novel therapeutic target to develop future intervention strategies.

Epicatechin Gallate Protects HBMVECs from Ischemia/Reperfusion Injury through Ameliorating Apoptosis and Autophagy and Promoting Neovascularization

Green tea is one of the most beverages with antioxidants and nutrients. As one of the major components of green tea, (-)-epicatechin gallate (ECG) was evaluated for its antioxidative properties in the present study. Cell proliferation assay, tube formation, cell migration, apoptosis, and autophagy were performed in human brain microvascular endothelial cells (HBMVECs) after oxygen-glucose deprivation/reoxygenation (OGD/R) to investigate potential anti-ischemia/reperfusion injury properties of ECG in vitro. Markers of oxidative stress as ROS, LDH, MDA, and SOD were further assayed in our study. Data indicated that ECG could affect neovascularization and promote cell proliferation, tube formation, and cell migration while inhibiting apoptosis and autophagy through affecting VEGF, Bcl-2, BAX, LC3B, caspase 3, mTOR, and Beclin-1 expression. All the data suggested that ECG may be protective for the brain against ischemia/reperfusion injury by promoting neovascularization, alleviating apoptosis and autophagy, and promoting cell proliferation in HBMVECs of OGD/R.

USP49 inhibits ischemia-reperfusion-induced cell viability suppression and apoptosis in human AC16 cardiomyocytes through DUSP1-JNK1/2 signaling

Dual-specificity protein phosphatases (DUSP) also known as mitogen-activated protein kinase (MAPK) phosphatases (MKPs) can dephosphorylate MAPKs, including extracellular signal-regulated kinase, c-Jun N-terminal kinase (JNK), and p38. DUSP1-mediated JNK dephosphorylation has been found to play an antiapoptotic role against cardiac ischemia-reperfusion (I/R) injury. However, the regulation of DUSP1-JNK pathway remains unclear. In the current study, ubiquitin-specific peptidase 49 (USP49) expression in human AC16 cardiomyocytes following I/R injury was measured by real-time polymerase chain reaction and western blot analysis. Cell viability, apoptosis, the Bax, Bcl-2, and DUSP1 expression, and the activity of MAPKs in AC16 cardiomyocytes following indicated treatment was measured by CCK-8, flow cytometry, and western blot analysis. The direct interaction between USP49 and DUSP1 was measured by coimmunoprecipitation and ubiquitination analysis. The effect of USP49 on apoptosis and JNK activity in rat cardiomyocytes following I/R injury was also measured by TUNEL and western blot analysis. Here, we found that USP49 expression was time-dependently increased in AC16 cardiomyocytes following I/R. I/R-induced cell apoptosis and JNK1/2 activation both in in vivo and in vitro reversed by USP49 overexpression in AC16 cardiomyocytes. Inhibiting JNK1/2 activation significantly inhibited USP49 knockdown-induced the cell viability inhibition, apoptosis and the JNK1/2 activation in AC16 cardiomyocytes. Moreover, USP49 positively regulated DUSP1 expression through deubiquitinating DUSP1. Overall, our findings establish USP49 as a novel regulator of DUSP1-JNK1/2 signaling pathway with a protective role in cardiac I/R injury.

Hepatocyte growth factor inhibits hypoxia/reoxygenation-induced activation of xanthine oxidase in endothelial cells through the JAK2 signaling pathway

Vascular endothelial cells (ECs) appear to be one of the primary targets of hypoxia/reoxygenation (H/R) injury. In our previous study, we demonstrated that hepatocyte growth factor (HGF) exhibited a protective effect in cardiac microvascular endothelial cells (CMECs) subjected to H/R by inhibiting xanthine oxidase (XO) by reducing the cytosolic Ca2+ concentration increased in response to H/R. The precise mechanisms through which HGF inhibits XO activation remain to be determined. In the present study, we examined the signaling pathway through which HGF regulates Ca2+ concentrations and the activation of XO during H/R in primary cultured rat CMECs. CMECs were exposed to 4 h of hypoxia and 1 h of reoxygenation. The protein expression of XO and the activation of the phosphoinositide 3-kinase (PI3K), janus kinase 2 (JAK2) and p38 mitogen-activated protein kinase (p38 MAPK) signaling pathways were detected by western blot analysis. Cytosolic calcium (Ca2+) concentrations and reactive oxygen species (ROS) levels were measured by flow cytometry. The small interfering RNA (siRNA)‑mediated knockdown of XO inhibited the increase in ROS production induced by H/R. LY294002 and AG490 inhibited the H/R-induced increase in the production and activation of XO. The PI3K and JAK2 signaling pathways were activated by H/R. The siRNA‑mediated knockdown of PI3K and JAK2 also inhibited the increase in the production of XO protein. HGF inhibited JAK2 activation whereas it had no effect on PI3K activation. The siRNA-mediated knockdown of JAK2 prevented the increase in cytosolic Ca2+ induced by H/R. Taken together, these findings suggest that H/R induces the production and activation of XO through the JAK2 and PI3K signaling pathways. Furthermore, HGF prevents XO activation following H/R primarily by inhibiting the JAK2 signaling pathway and in turn, inhibiting the increase in cytosolic Ca2+.

Hypoxia/ischemia promotes CXCL10 expression in cardiac microvascular endothelial cells by NFkB activation

CXCL10, the chemokine with potent chemotactic activity on immune cells and other non-immune cells expressing its receptor CXCR3, has been demonstrated to involve in myocardial infarction, which was resulted from hypoxia/ischemia. The cardiac microvascular endothelial cells (CMECs) are the first cell type which is implicated by hypoxia/ischemia. However, the potential molecular mechanism by which hypoxia/ischemia regulates the expression of CXCL10 in CMECs remains unclear. In the present study, the expression of CXCL10 was firstly examined by real-time PCR and ELISA analysis. Several potential binding sites (BS) for transcription factors including NF-kappaB (NFkB), HIF1 alpha (HIF1α) and FoxO3a were identified in the promoter region of CXCL10 gene from -2000 bp to -1 bp using bioinformatics software. Luciferase reporter gene vectors for CXCL10 promoter and for activation of above transcription factors were constructed. The activation of NFkB, hypoxia-inducible transcription factor-1 alpha (HIF-1α) and FoxO3a was also analyzed by Western blotting. It was shown that the production of CXCL10 in CMECs was significantly increased by hypoxia/ischemia treatment, in parallel with the activation of CXCL10 promoter examined by reporter gene vector system. Furthermore, transcription factors including NFkB, HIF1α and FoxO3a were activated by hypoxia/ischemia in CMECs. However, over-expression of NFkB, but not that of HIF1α or FoxO3a, significantly promoted the activation of CXCL10 promoter reporter gene. These findings indicated that CXCL10 production in CMECs was significantly increased by hypoxia/ischemia, at least in part, through activation of NFkB pathway and subsequently binding to CXCL10 promoter, finally promoted the transcription of CXCL10 gene.

Research advances in HMGN5 and cancer

High-mobility group nucleosome-binding domain 5 (HMGN5) is a new member of the high-mobility group N (HMGN) protein family that is involved in nucleosomal binding and transcriptional activation. It was first discovered in mouse, and recent studies found that the expressions of HMGN5 in many human cancers were also highly regulated, such as prostate, bladder, breast, and lung and clear cell renal cell carcinoma. Numerous reports have demonstrated that HMGN5 plays significant roles in many biological and pathological conditions, such as in developmental defects, hypersensitivity to stress, embryonic stem cell differentiation, and tumor progression. Importantly, deficiency of HMGN5 has been shown to be linked to cancer cell growth, cell cycle regulation, migration, invasion, and clinical outcomes, and it represents a promising therapeutic target for many malignant tumors. In the present review, we provide an overview of the current knowledge concerning the role of HMGN5 in cancer development and progression.

The Green Tea Component (-)-Epigallocatechin-3-Gallate Sensitizes Primary Endothelial Cells to Arsenite-Induced Apoptosis by Decreasing c-Jun N-Terminal Kinase-Mediated Catalase Activity

The green tea component (-)-epigallocatechin-3-gallate (EGCG) has been shown to sensitize many different types of cancer cells to anticancer drug-induced apoptosis, although it protects against non-cancerous primary cells against toxicity from certain conditions such as exposure to arsenic (As) or ultraviolet irradiation. Here, we found that EGCG promotes As-induced toxicity of primary-cultured bovine aortic endothelial cells (BAEC) at doses in which treatment with each chemical alone had no such effect. Increased cell toxicity was accompanied by an increased condensed chromatin pattern and fragmented nuclei, cleaved poly(ADP-ribose) polymerase (PARP), activity of the pro-apoptotic enzymes caspases 3, 8 and 9, and Bax translocation into mitochondria, suggesting the involvement of an apoptotic signaling pathway. Fluorescence activated cell sorting analysis revealed that compared with EGCG or As alone, combined EGCG and As (EGCG/As) treatment significantly induced production of reactive oxygen species (ROS), which was accompanied by decreased catalase activity and increased lipid peroxidation. Pretreatment with N-acetyl-L-cysteine or catalase reversed EGCG/As-induced caspase activation and EC toxicity. EGCG/As also increased the phosphorylation of c-Jun N-terminal kinase (JNK), which was not reversed by catalase. However, pretreatment with the JNK inhibitor SP600125 reversed all of the observed effects of EGCG/As, suggesting that JNK may be the most upstream protein examined in this study. Finally, we also found that all the observed effects by EGCG/As are true for other types of EC tested. In conclusion, this is firstly to show that EGCG sensitizes non-cancerous EC to As-induced toxicity through ROS-mediated apoptosis, which was attributed at least in part to a JNK-activated decrease in catalase activity.

Epigallocatechin-3-gallate and zinc provide anti-apoptotic protection against hypoxia/reoxygenation injury in H9c2 rat cardiac myoblast cells

It has previously been demonstrated that phosphatidylinositol-3-kinase (PI3K)/Akt and cleaved caspase-3 serve critical roles in the apoptosis of cardiac myocytes following ischemia/reperfusion injury. Epigallocatechin-3-gallate (EGCG), the predominant catechin component of green tea, has been reported to have potential cardioprotective effects in primary cultures of cardiac myocytes exposed to I/R injury, mediated through inhibition of signal transducers and activators of transcription-1 activity. In addition, it is also known that the biological behavior of EGCG may be influenced by metal ions, for example the hepatoprotective activity of EGCG has been reported to be enhanced by zinc. In the present study, the protective effects of EGCG with zinc were assessed on cultures of rat cardiac myoblasts exposed to hypoxia/reoxygenation (H/R) injury. H9c2 cells were subjected to 3-h hypoxia, followed by 1-h reperfusion. EGCG and/or zinc were perfused prior to induced hypoxic stress. It was demonstrated that when EGCG interacted with zinc, the anti-apoptotic activity was significantly enhanced. To the best of our knowledge, the current study was the first to demonstrate that EGCG + Zn(2+) protects H9c2 cells against H/R injury through activation of the PI3K/Akt pathway, as determined by western blotting. Since EGCG + Zn(2+) may, at least in part, protect cardiac myocytes against H/R-induced apoptotic cell death, the PI3K/Akt pathway of EGCG may be enhanced by its interactions with zinc during H/R injury. Furthermore, it was suggested that a similar procedure may be implemented in a clinical setting, in order to maximize PI3K/Akt activation levels in patients with acute coronary artery disease. EGCG and zinc may therefore represent effective agents for use in the prevention of I/R injury in clinical practice.

Epigallocatechin Gallate: A Review of Its Beneficial Properties to Prevent Metabolic Syndrome

Obesity and being overweight are linked with a cluster of metabolic and vascular disorders that have been termed the metabolic syndrome. This syndrome promotes the incidence of cardiovascular diseases that are an important public health problem because they represent a major cause of death worldwide. Whereas there is not a universally-accepted set of diagnostic criteria, most expert groups agree that this syndrome is defined by an endothelial dysfunction, an impaired insulin sensitivity and hyperglycemia, dyslipidemia, abdominal obesity and hypertension. Epidemiological studies suggest that the beneficial cardiovascular health effects of diets rich in green tea are, in part, mediated by their flavonoid content, with particular benefits provided by members of this family such as epigallocatechin gallate (EGCG). Although their bioavailability is discussed, various studies suggest that EGCG modulates cellular and molecular mechanisms of various symptoms leading to metabolic syndrome. Therefore, according to in vitro and in vivo model data, this review attempts to increase our understanding about the beneficial properties of EGCG to prevent metabolic syndrome.

Protective effects of epigallocatechin-3-gallate on intestinal ischemia reperfusion injury through enhanced activation of PI3K/Akt pathway in rats

Inflammation plays a critical role in intestinal ischemia reperfusion injury (IRI). Epigallocatechin-3-gallate (EGCG) has been demonstrated to possess anti-inflammatory effect. This study examined the effect of EGCG on intestinal IRI and explored the possible mechanisms. Male Wistar rats were randomly divided into three groups: sham-operated group (Sham), IRI control group (IRI) and IRI-EGCG group (EGCG). Rats in IRI-EGCG group were administered dissolved EGCG in drinking water (0.4 mg/mL) for 14 days prior to IRI induction. A rat model of intestinal IRI was established by ligating the superior mesenteric artery (SMA) for 30 min, followed by reperfusion for 1 h. Intestinal histology, pro-inflammatory cytokines and mediators were examined and the effect of EGCG on PI3K/Akt signalling was assessed. EGCG significantly alleviated the pathological changes of the intestine and suppressed the IRI-induced up-regulation of TNF-α, IL-1 and IL-6 mRNA and protein expression in the serum and intestine. The mechanism might be that EGCG enhanced the activation of PI3K/Akt signalling pathway. In conclusion, the administration of EGCG can significantly mitigate the acute intestinal IRI in rats by enhancing the activation of PI3K/Akt signalling pathway to suppress inflammatory response and might be a promising alternative for the prevention or treatment of intestinal IRI in the clinical practice.

Cardioprotective Effect of Licochalcone D against Myocardial Ischemia/Reperfusion Injury in Langendorff-Perfused Rat Hearts

Flavonoids are important components of ‘functional foods’, with beneficial effects on cardiovascular function. The present study was designed to investigate whether licochalcone D (LD) could be a cardioprotective agent in ischemia/reperfusion (I/R) injury and to shed light on its possible mechanism. Compared with the I/R group, LD treatment enhanced myocardial function (increased LVDP, dp/dt_max, dp/dt_min, HR and CR) and suppressed cardiac injury (decreased LDH, CK and myocardial infarct size). Moreover, LD treatment reversed the I/R-induced cleavage of caspase-3 and PARP, resulting in a significant decrease in proinflammatory factors and an increase in antioxidant capacity in I/R myocardial tissue. The mechanisms underlying the antiapoptosis, antiinflammation and antioxidant effects were related to the activation of the AKT pathway and to the blockage of the NF-κB/p65 and p38 MAPK pathways in the I/R-injured heart. Additionally, LD treatment markedly activated endothelial nitric oxide synthase (eNOS) and reduced nitric oxide (NO) production. The findings indicated that LD had real cardioprotective potential and provided support for the use of LD in myocardial I/R injury.

Epigallocatechin-3-gallate inhibits VCAM-1 expression and apoptosis induction associated with LC3 expressions in TNFα-stimulated human endothelial cells

Tumor necrosis factor alpha (TNF-α) promotes the expression of adhesion molecules and induces endothelial dysfunction, a process that can lead to atherosclerosis. Green tea consumption can inhibit endothelial dysfunction and attenuate the development of arteriosclerosis. The purpose of this study was to examine whether epigallocatechin-3-gallate (EGCG) prevents TNF-α-dependent endothelial dysfunction. Here, we compared the regulatory effects of the green tea components EGCG and L-theanine against TNF-α-induced stimulation of adhesion molecule expression and apoptosis induction, which is associated with autophagy. Monocytic cell adhesion to human endothelial cells was measured using a fluorescently-labeled cell line, U-937. Caspase 3/7 activity was examined with a fluorescent probe and fluorescence microscopy. In addition, we analyzed the expression of several genes by RT-PCR. TNF-α-modulation of LC3 and VCAM1 protein levels were investigated by Western blot (WB). TNF-α induced adhesion of U937 cells to endothelial cells, and gene expression associated with adhesion molecules and apoptosis. On the other hand, EGCG and L-theanine inhibited TNF-α-induced adhesion of U937 cells to endothelial cells and inhibited increases in ICAM1, CCL2 and VCAM1 expression. Furthermore, EGCG and L-theanine inhibited TNF-α-induced apoptosis-related gene expression (e.g., CASP9), and caspase activity while inhibiting TNFα-induced VCAM1, LC3A and LC3B protein expression. Meanwhile, treatment of endothelial cells with autophagy inhibitor 3-methyladenine (3-MA) blocked EGCG-induced expression of CASP9. Together, these results indicate that EGCG can modulate TNF-α-induced monocytic cell adhesion, apoptosis and autophagy. We thus conclude that EGCG might be beneficial for inhibiting TNF-α-mediated human endothelial disorders by affecting LC3 expression-related processes.

Inhibition of 12/15 lipoxygenase by baicalein reduces myocardial ischemia/reperfusion injury via modulation of multiple signaling pathways

12/15-Lipoxygenase (LOX) is a member of the LOX family that catalyzes the step from arachidonic acid to hydroxy-eicosatetraenoic acids (HETEs). Previous studies demonstrated that 12/15-LOX plays a critical role in the development of atherosclerosis, hypertension, heart failure, and other diseases; however, its role in myocardial ischemic injury was contraversal. Here, we investigated the inhibition of 12/15-LOX by baicalein on acute cardiac injury and dissected its molecular mechanism. In a mouse model of acute ischemia/reperfusion (I/R) injury, 12/15-LOX was significantly upregulated in the peri-infarct area surrounding the primary infarction. In cultured cardiac myocytes, baicalein suppressed apoptosis and caspase 3 activity in response to simulated ischemia/reperfusion (I/R). Moreover, administration of 12/15-LOX inhibitor, baicalein, significantly attenuated myocardial infarct size induced by I/R injury. Moreover, baicalein treatment significantly inhibited cardiomyocyte apoptosis, inflammatory responses and oxidative stress in the heart after I/R injury. The mechanisms underlying these effects were associated with the activation of ERK1/2 and AKT pathways and inhibition of activation of p38 MAPK, JNK1/2, and NF-kB/p65 pathways in the I/R-treated hearts and neonatal cardiomyoctes. Our data indicated that 12/15-LOX inhibitor baicalein can prevent myocardial I/R injury by modulation of multiple mechanisms, and suggest that baicalein could represent a novel therapeutic drug for acute myocardial infarction.

Senescent cardiac fibroblast is critical for cardiac fibrosis after myocardial infarction

Senescence is a recognized mechanism of cardiovascular diseases; however, its contribution to myocardial fibrosis and rupture after infarction and the underlying mechanisms remain unclear. Here we showed that senescent cardiac fibroblasts markedly accumulated in heart after myocardial infarction. The expression of key senescence regulators, especially p53, was significantly up-regulated in the infarcted heart or hypoxia-treated fibroblasts. Furthermore, knockdown of endogenous p53 by siRNA in fibroblasts markedly reduced hypoxia-induced cell senescence, cytokine expression but increased collagen expression, whereas increased expression of p53 protein by adenovirus infection had opposite effects. Consistent with in vitro results in cardiac fibroblasts, p53 deficiency in vivo significantly decreased the accumulation of senescent fibroblasts, the infiltration of macrophages and matrix metalloproteinases, but enhanced collagen deposition after myocardial infarction. In conclusion, these results suggest that the p53-mediated fibroblast senescence limits cardiac collagen production, and inhibition of p53 activity could represent a novel therapeutic target to increase reparative fibrosis and to prevent heart rupture after myocardial infarction.

Involvement of the FoxO3a pathway in the ischemia/reperfusion injury of cardiac microvascular endothelial cells

FoxO3a, a member of the forkhead transcription factors, has been demonstrated to be involved in myocardial ischemia/reperfusion (I/R) injury. Cardiac microvascular endothelial cells (CMECs) are some of the predominant cells damaged immediately after myocardial I/R injury. Despite the importance of injured CMECs in an ischemic heart, little is known about the involvement of FoxO3a in regulating CMECs injury. Thus, we used rat CMECs following simulated I/R to examine FoxO3a activation and signaling in relation to survival, the cell cycle and apoptosis in CMECs. We found that Akt negatively regulates activation of the FoxO3a pathway by phosphorylating FoxO3a in CMECs as demonstrated with an Akt inhibitor and activator. Upon I/R injury, the FoxO3a pathway was significantly activated in CMECs, which was accompanied by Akt deactivation. In parallel, the I/R of CMECs induced G1-phase arrest through p27(Kip1) up-regulation and significant activation of caspase-3. Accordingly, inhibition of the FoxO3a pathway by IGF-1, an Akt activator, could significantly block the I/R-enhanced activation of p27(Kip1) and caspase-3 in CMECs. Collectively, our results indicate that the FoxO3a pathway is involved in the I/R injury of CMECs at least in part through the regulation of cell cycle arrest and apoptosis, suggesting that the FoxO3a pathway may be a novel therapeutic target that protects against microvascular endothelial damage in ischemic hearts.

Pro-apoptotic effect of epigallo-catechin-3-gallate on B lymphocytes through regulating BAFF/PI3K/Akt/mTOR signaling in rats with collagen-induced arthritis

To investigate the role of PI3K/Akt/mTOR signaling mediated by B cell-activating factor belonging to the TNF family (BAFF) involved in anti-apoptosis of B lymphocytes in rats with collagen-induced arthritis (CIA) and the regulation of epigallo-catechin-3-gallate (EGCG). Sprague-Dawley rats were immunized to induce CIA. CIA rats were randomly separated into different groups and treated with EGCG (40, 80 mg/kg), Paeoniflorin (100mg/kg) from day 18 to day 38 after immunization. The effects of EGCG on B lymphocytes were evaluated by the levels of BAFF, anti-CII antibody, IgA, IgG and IgM, and the expressions of BAFF receptor, P110δ, p-Akt, mTORC1, Bcl-xL and Bim. B lymphocyte proliferations were analyzed by MTT assay. Apoptosis of B lymphocyte were assayed by flow cytometry. Results showed that, in CIA rats, the levels of BAFF, anti-CII antibody, IgA, IgG and IgM enhanced. BAFF receptor, P110δ, p-AKT, mTORC1 and Bcl-xL were expressed highly, while Bim expression decreased. EGCG (40, 80 mg/kg) and Paeoniflorin decreased the levels of BAFF, anti-CII antibody, IgA, IgG, IgM and the expressions of BAFF receptor, P110δ, p-AKT, mTORC1, Bcl-xL in CIA rats, and increased Bim expression. Further studies showed that EGCG could reduce the expression of P110δ and mTORC1 in vitro. EGCG inhibited B lymphocyte proliferation and induced B lymphocyte apoptosis. In conclusion, BAFF/BAFF receptor might regulate B cell anti-apoptosis through PI3K/Akt/mTOR pathway. EGCG had therapeutic effects on CIA rats, which might be relative to the inhibition effects of EGCG on BAFF and PI3K/Akt/mTOR signaling, and then the apoptosis of B lymphocytes was promoted further.

Attenuation of age-related changes in FOXO3a activity and the PI3K/Akt pathway by short-term feeding of ferulate

Ferulate (4-hydroxy-3-methoxycinnamic acid) is a well-known phenolic compound that scavenges free radicals and exerts anti-inflammatory effects. Forkhead box O3a (FOXO3a), a transcription factor that plays important roles in aging processes, decreases with age and is negatively regulated through phosphorylation by phosphatidylinositol 3-kinase (PI3K)/Akt signaling. The present study investigated the efficacy of short-term ferulate feeding on age-related changes in PI3K/Akt/FOXO3a and upstream insulin signaling pathways in aged rats. In addition, changes in manganese superoxide dismutase (MnSOD) and catalase expression were examined because of their dependence on PI3K/Akt/FOXO3a activity. Short-term feeding experiments were done with a diet containing ferulate that was given to aged rats at doses of 3 or 6 mg kg(-1) day(-1) for 10 days. Results showed that FOXO3a activity was increased in the ferulate-fed old group compared with the control old group. Also, ferulate suppressed the PI3K/Akt signaling pathway that is responsible for FOXO3a inhibition in aged rats. Plasma insulin levels and the upstream insulin signaling pathway were also modulated by ferulate correspondingly with PI3K/Akt/FOXO3a activity. The age-related decrease in two major antioxidant enzymes, MnSOD and catalase, was blunted by ferulate, which was accompanied by FOXO3a transcriptional activity. The significance of the present study is the finding that short-term feeding of ferulate effectively modulates age-related renal FOXO3a, PI3K/Akt and insulin signaling pathways, and MnSOD and catalase expression, all of which may be beneficial for attenuating the aging process.

Glutathione homeostasis and functions: potential targets for medical interventions

Glutathione (GSH) is a tripeptide, which has many biological roles including protection against reactive oxygen and nitrogen species. The primary goal of this paper is to characterize the principal mechanisms of the protective role of GSH against reactive species and electrophiles. The ancillary goals are to provide up-to-date knowledge of GSH biosynthesis, hydrolysis, and utilization; intracellular compartmentalization and interorgan transfer; elimination of endogenously produced toxicants; involvement in metal homeostasis; glutathione-related enzymes and their regulation; glutathionylation of sulfhydryls. Individual sections are devoted to the relationships between GSH homeostasis and pathologies as well as to developed research tools and pharmacological approaches to manipulating GSH levels. Special attention is paid to compounds mainly of a natural origin (phytochemicals) which affect GSH-related processes. The paper provides starting points for development of novel tools and provides a hypothesis for investigation of the physiology and biochemistry of glutathione with a focus on human and animal health.

Epigallocatechin gallate (EGCG) inhibits type II phosphatidylinositol 4-kinases: a key component in pathways of phosphoinositide turnover

Type II phosphatidylinositol (PtdIns) 4-kinases produce PtdIns 4-phosphate, an early key signaling molecule in phosphatidylinositol cycle, which is indispensable for T cell activation. Type II PtdIns 4-kinase alpha and beta have similar biochemical properties. To distinguish these isoforms Epigallocatechin gallate (EGCG) has been evaluated as a specific inhibitor. EGCG is the major active catechin in green tea having anti-inflammatory, antiatherogenic and cancer chemopreventive properties. The precise mechanism of actions and molecular targets of EGCG in early signaling cascades are not well understood. In the present study, we have shown that EGCG inhibits type II PtdIns 4-kinases (α and β isoforms) and PtdIns 3-kinase activity in vitro. EGCG directly bind to both alpha and beta isoforms of type II PtdIns 4-kinases with a Kd of 2.62 μM and 1.02 μM, respectively. Type II PtdIns 4-kinase-EGCG complex have different binding pattern at its excited state. Both isoforms showed significant change in helicity upon binding with EGCG. EGCG modulates its effect by interacting with ATP binding pocket; the residues likely to be involved in EGCG binding were predicted by Autodock. Our findings suggest that EGCG inhibits two isoforms and could be a key to regulate T cell activation.

FOXO3a inhibits TNF-α- and IL-1β-induced astrocyte proliferation:Implication for reactive astrogliosis

Reactive astrogliosis is one of the pathological hallmarks of neurodegenerative diseases. Inflammatory cytokines, such as TNF-α and IL-1β, have been shown to mediate the reactive astrogliosis in neurodegenerative diseases; however, the molecular mechanism remains unclear. In this study, we investigated the role of transcription factor FOXO3a on astrocyte proliferation, one primary aspect of severe reactive astrogliosis. Our results confirmed that TNF-α and IL-1β increased astrocyte proliferation, as determined by Ki67 and BrdU immunostaining. Furthermore, we found that cytokine-mediated astrocyte proliferation was accompanied by an increase of the phosphorylation and reduced nuclear expression of FOXO3a. Intracranial injection of TNF-α and IL-1β induced astrocyte proliferation and hypertrophy, which was associated with reduced nuclear expression of Foxo3a in astrocytes. To determine the function of FOXO3a in astrocyte proliferation, wild type FOXO3a was overexpressed with adenovirus, which subsequently upregulated p27Kip1 and Gadd45α, and significantly inhibited cytokine-induced astrocyte proliferation. In contrast, overexpression of dominant negative FOXO3a decreased p27Kip1, upregulated cyclin D1 and promoted astrocyte proliferation. Along the same line, astrocytes isolated from Foxo3a-null mice have higher proliferative potential. In response to intracranial injection of cytokines, Foxo3a-null mice manifested severe astrogliosis in vivo. In conclusion, FOXO3a is important in restraining astrocyte proliferation during proinflammatory cytokine stimulation and loss of function of FOXO3a may be responsible for the proliferation of astrocytes in the severe form of reactive astrogliosis. Understanding the key regulatory role of FOXO3a in reactive astrogliosis may provide a novel therapeutic target during neuroinflammation.

Epigallocatechin-3-gallate (EGCG) attenuates inflammation in MRL/lpr mouse mesangial cells

Epigallocatechin-3-gallate (EGCG), a bioactive component of green tea, has been reported to exert anti-inflammatory effects on immune cells. EGCG is also shown to activate the metabolic regulator, adenosine 5'-monophosphate-activated protein kinase (AMPK). Reports have also indicated that EGCG inhibits the immune-stimulated phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. The PI3K/Akt/mTOR pathway has been implicated in mesangial cell activation in lupus. Mesangial cells from MRL/lpr lupus-like mice are hyper-responsive to immune stimulation and overproduce nitric oxide (NO) and other inflammatory mediators when stimulated. In our current studies, we sought to determine the mechanism by which EGCG attenuates immune-induced expression of pro-inflammatory mediators. Cultured mesangial cells from MRL/lpr mice were pre-treated with various concentrations of EGCG and stimulated with lipopolysaccharide (LPS)/interferon (IFN)-gamma. EGCG activated AMPK and blocked LPS/IFN-gamma-induced inflammatory mediator production (iNOS expression, supernatant NO and interleukin-6). Interestingly, EGCG attenuated inflammation during AMPK inhibition indicating that the anti-inflammatory effect of EGCG may be partially independent of AMPK activation. Furthermore, we found that EGCG effectively inhibited the immune-stimulated PI3K/Akt/mTOR pathway independently of AMPK, by decreasing phosphorylation of Akt, suggesting an alternate mechanism for EGCG-mediated anti-inflammatory action in mesangial cells. Taken together, these studies show that EGCG attenuated inflammation in MRL/lpr mouse mesangial cells via the PI3K/Akt/mTOR pathway. Our findings suggest a potential therapeutic role for the use of EGCG to regulate inflammation and control autoimmune disease.

Green tea catechins improve human forearm vascular function and have potent anti-inflammatory and anti-apoptotic effects in smokers

OBJECTIVE

Several epidemiological investigations have reported that green tea reduces cardiovascular and cerebral vascular risks. Green tea catechins may improve peripheral endothelial dysfunction in smokers. The purpose of this study was to elucidate the beneficial effect of green tea catechins on the repair of endothelial dysfunction in smokers.

METHODS

Thirty healthy male smokers divided into three groups ingested a green tea beverage containing 0 mg (control group), 80 mg (middle dose group) or 580 mg (high dose group) of green tea catechins (GTC) daily for two weeks, and endothelial-dependent vasodilatation was investigated by measuring forearm blood flow (FBF) response to reactive hyperemia (RH) by venous occlusion strain-gauge plethysmography.

RESULTS

An acute effect was that the FBF response to RH significantly increased 2 hr after GTC intake in the high dose group. However, no increase was observed in the other groups. The chronic administration of GTC for one or two weeks ameliorated the FBF responses to RH in the high dose group. On the other hand, no significant increase was observed in the FBF responses to RH in the other groups. Moreover, the plasma concentration of 8-OHdG, IL-6, TNF-alpha, and soluble Fas decreased significantly for two weeks in the high dose group, however, the level of IL-1 beta remained unchanged over this period.

CONCLUSION

Green tea consumption over short and long periods appears to ameliorate endothelial dysfunction by scavenging free radicals with anti-inflammatory and anti-apoptotic properties in healthy male smokers.