Dietary flavonoids differentially reduce oxidized LDL-induced apoptosis in human endothelial cells: role of MAPK- and JAK/STAT-signaling

Quercetin Attenuates KLF4-Mediated Phenotypic Switch of VSMCs to Macrophage-like Cells in Atherosclerosis: A Critical Role for the JAK2/STAT3 Pathway

The objective of this study was to elucidate the protective role of quercetin in atherosclerosis by examining its effect on the phenotypic switch of vascular smooth muscle cells (VSMCs) to macrophage-like cells and the underlying regulatory pathways. Aorta tissues from apolipoprotein E-deficient (ApoE KO) mice fed a high-fat diet (HFD), treated with or without 100 mg/kg/day quercetin, were analyzed for histopathological changes and molecular mechanisms. Quercetin was found to decrease the size of atherosclerotic lesions and mitigate lipid accumulation induced by HFD. Fluorescence co-localization analysis revealed a higher presence of macrophage-like vascular smooth muscle cells (VSMCs) co-localizing with phospho-Janus kinase 2 (p-JAK2), phospho-signal transducer and activator of transcription 3 (p-STAT3), and Krüppel-like factor 4 (KLF4) in regions of foam cell aggregation within aortic plaques. However, this co-localization was reduced following treatment with quercetin. Quercetin treatment effectively inhibited the KLF4-mediated phenotypic switch in oxidized low-density lipoprotein (ox-LDL)-loaded mouse aortic vascular smooth muscle cells (MOVAS), as indicated by decreased expressions of KLF4, LGALS3, CD68, and F4/80, increased expression of alpha smooth muscle actin (α-SMA), reduced intracellular fluorescence Dil-ox-LDL uptake, and decreased lipid accumulation. In contrast, APTO-253, a KLF4 activator, was found to reverse the effects of quercetin. Furthermore, AG490, a JAK2 inhibitor, effectively counteracted the ox-LDL-induced JAK2/STAT3 pathway-dependent switch to a macrophage-like phenotype and lipid accumulation in MOVAS cells. These effects were significantly mitigated by quercetin but exacerbated by coumermycin A1, a JAK2 activator. Our research illustrates that quercetin inhibits the KLF4-mediated phenotypic switch of VSMCs to macrophage-like cells and reduces atherosclerosis by suppressing the JAK2/STAT3 pathway.

Advances in the Anti-Atherosclerotic Mechanisms of Epigallocatechin Gallate

Atherosclerosis (AS) is a common clinical sickness and the major pathological basis of ischemic cardiocerebrovascular diseases (CCVDs). The pathogenesis of AS involves a variety of risk factors, and there is a lack of effective preventive and curative drugs that can completely treat AS. In recent years, with the improvement of people's living standards and changes in dietary habits, the morbidity and mortality rates of AS are on the rise, and the age of onset tends to be younger. The formation of AS is closely related to a variety of factors, and the main factors include lipid metabolism disorders, endothelial damage, inflammation, unstable plaques, etc. Epigallocatechin gallate (EGCG), as one of the main components of catechins, has a variety of pharmacological effects, and its role in the prevention of AS and the protection of cardiovascular and cerebral blood vessels has been highly valued. Recent epidemiological investigations and various in vivo and ex vivo experiments have shown that EGCG is capable of resisting atherosclerosis and reducing the morbidity and mortality of AS. In this paper, we reviewed the anti-AS effects of EGCG and its mechanisms in recent years, including the regulation of lipid metabolism, regulation of intestinal flora disorders, improvement of vascular endothelial cell functions, inhibition of inflammatory factors expression, regulation of inflammatory signaling pathways, inhibition of matrix metalloproteinase (MMP) expression, and inhibition of platelet aggregation, which are helpful for the prevention of cardiocerebrovascular diseases.

Gut-Brain Axis in Focus: Polyphenols, Microbiota, and Their Influence on α-Synuclein in Parkinson's Disease

With the recognition of the importance of the gut-brain axis in Parkinson's disease (PD) etiology, there is increased interest in developing therapeutic strategies that target α-synuclein, the hallmark abhorrent protein of PD pathogenesis, which may originate in the gut. Research has demonstrated that inhibiting the aggregation, oligomerization, and fibrillation of α-synuclein are key strategies for disease modification. Polyphenols, which are rich in fruits and vegetables, are drawing attention for their potential role in this context. In this paper, we reviewed how polyphenols influence the composition and functional capabilities of the gut microbiota and how the resulting microbial metabolites of polyphenols may potentially enhance the modulation of α-synuclein aggregation. Understanding the interaction between polyphenols and gut microbiota and identifying which specific microbes may enhance the efficacy of polyphenols is crucial for developing therapeutic strategies and precision nutrition based on the microbiome.

Pre exposure to enriched environment alleviates brain injury after ischemia-reperfusion by inhibiting p38MAPK/STAT1 pathway

BACKGROUND

Stroke is one of the major diseases that endangers human health. It is widely reported that enriched environment (EE) can improve the neurological function in different brain injury models. Recently, relevant researches have indicated that MAPK pathway is closely related to the inflammatory response in nervous system related diseases. However, whether pre exposure to EE (EE pretreatment) has a preventive effect, and its mechanism are not clear. Therefore, this study aimed to determine the possible benefits and related mechanisms of EE in preventing brain injury after acute ischemia-reperfusion.

METHODS

Adult Sprague Dawley rats were kept in enriched or standardized environments for 21 days. Then the middle cerebral artery of rats was occluded for one hour and 30 min, and then reperfusion was performed. Then their neurological deficit score was evaluated. Cerebral edema, along with ELISA and protein quantities of p38MAPK, JNK, ERK, IL-1β, TNF-α, and co-localization of Iba1 were assessed. Changes in neuroinflammation and apoptosis were also detected in the penumbra cortex.

RESULTS

Our research showed that EE pretreatment significantly alleviated acute cerebral ischemia-reperfusion injury in rats. Including the reduction of brain edema and apoptosis, and the improvement of neurological scores. In addition, the protein level of p38MAPK was significantly down regulated in EE pretreatment group, and the downstream protein STAT1 had the same trend. In addition, immunofluorescence results showed that Iba1 in EE pretreatment group decreased, the ELISA results showed that the classical proinflammatory cytokines increased significantly, while anti-inflammatory cytokines in EE pretreatment group increased, and the same results were obtained by Western blot analysis.

CONCLUSION

On the whole, our research demonstrated that EE pretreatment can have a protective effect on the organism by inhibiting the p38 MAPK/STAT1 pathway. Thus, EE can be one of the most promising means of disease prevention. Secondly, p38MAPK/STAT1 pathway may be a latent target for the prevention of acute ischemic stroke.

Cadmium contributes to atherosclerosis by affecting macrophage polarization

Chronic cadmium (Cd) exposure contributes to the progression of atherosclerosis, but the direct role of Cd and its mechanisms in atherosclerosis remains incompletely understood. Atherosclerosis is a chronic inflammatory disease promoting macrophage polarization to M1 phenotype and producing pro-inflammations that are vital in regulating the inflammatory response. Herein, through a case-control study, we found that Cd exposure may promote the occurrence of carotid plaque via inflammation, where interleukin-6 (IL-6) may play an important role. We also combined in vivo and in vitro experiments to explore the underlying mechanism of Cd-promoted plaque formation and the production of IL-6. With or without cadmium chloride (CdCl₂) fed ApoE^-/- mouse and treated RAW264.7 cells, we found Cd accumulated in the aortas which significantly increased the plaque area in atherosclerotic mice, macrophage accumulation, and lipid accumulation, and Cd promoted M1 phenotype macrophage polarization reflected by the increased expression of CD86 which produced tumor necrosis factor-α (TNF-α) and IL-6. However, the influences on M2 phenotype and anti-inflammatory cytokines interleukin-4 (IL-4) and interferon-γ (IFN-γ) were non-significant. Moreover, we found that JAK2/STAT3 pathway was greatly activated in the plaques and CdCl₂-treated macrophages. The inhibition of JAK2/STAT3 substantially reversed the Cd-stimulated macrophage M1 phenotype macrophage polarization and the expression of pro-inflammatory cytokines including TNF-α and IL-6. Altogether, Cd intensifies atherosclerosis by modulating macrophage polarization via JAK2/STAT3 to up-regulated the expression of IL-6.

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Xanthatin Alleviates LPS-Induced Inflammatory Response in RAW264.7 Macrophages by Inhibiting NF-κB, MAPK and STATs Activation

Xanthatin (XT) is a sesquiterpene lactone isolated from the Chinese herb Xanthium, which belongs to the Asteraceae family. In this study, we developed an inflammation model via stimulating macrophage cell line (RAW 264.7 cells) with lipopolysaccharide (LPS), which was applied to assess the anti-inflammatory effect and probable mechanisms of xanthatin. When compared with the only LPS-induced group, cells that were pretreated with xanthatin were found to decrease the amount of nitric oxide (NO), reactive oxygen species (ROS) and associated pro-inflammatory factors (TNF-α, IL-1β and IL-6), and downregulate the mRNA expression of iNOS, COX-2, TNF-α, IL-1β, and IL-6. Interestingly, phosphorylated levels of related proteins (STAT3, ERK1/2, SAPK/JNK, IκBα, p65) were notably increased only with the LPS-activated cells, while the expression of these could be reverted by pre-treatment with xanthatin in a dose-dependent way. Meanwhile, xanthatin was also found to block NF-κB p65 from translocating into the nucleus and activating inflammatory gene transcription. Collectively, these results demonstrated that xanthatin suppresses the inflammatory effects through downregulating the nuclear factor kappa-B (NF-κB), mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription (STATs) signaling pathways. Taken together, xanthatin possesses the potential to act as a good anti-inflammatory medication candidate.

Potential roles of dietary flavonoids from Citrus aurantium L. var. amara Engl. in atherosclerosis development

Dietary consumption of flavonoids correlated positively with lower risk of cardiovascular disease. However, the precise roles of flavonoids from the blossoms of Citrus aurantium Linn variant amara Engl (CAVA) in atherosclerosis (AS) are still poorly understood. This study aimed to find novel flavonoid-type skeletons with protection against AS. Total flavonoids (CAVAF), homoeriodictyol (HE) and hesperetin-7-O-β-d-glucopyranoside (HG) were isolated from the blossoms of Citrus aurantium Linn variant amara Engl. by chromatography. Their suppressive effects on lipopolysaccharide (LPS)-induced inflammatory responses and ox-LDL-induced foam cell formation were systematically and comparatively investigated using macrophage RAW264.7 cells. HE was more powerful than HG in inhibiting LPS-induced production of nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and gene expression in RAW264.7 cells. HE and HG showed different responses to extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), P38, P65, IκBα, IκKα/β phosphorylation, and nuclear factor-kappa B (NF-κB) nuclear translocation. HE and HG also differentially decreased oxidized low-density lipoprotein (ox-LDL)-induced foam cell formation by regulating peroxisome proliferator-activated receptor-gamma (PPARγ), phospholipid ATP-binding cassette transporter A1 (ABCA1), phospholipid ATP-binding cassette transporter G1 (ABCG1), scavenger receptor class B type I (SRB1), scavenger receptor class A type I (SRA1) and cluster of differentiation 36 (CD36) expression at gene and protein levels in RAW264.7 cells. HG showed weaker potential than HE in preventing AS development. Their chemical differences might partially explain the discrepancy in their bioactivity. In conclusion, HE and HG might be developed into novel therapeutic agents against inflammation and AS-associated diseases.

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.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Quercetin shows anti-tumor effect in hepatocellular carcinoma LM3 cells by abrogating JAK2/STAT3 signaling pathway

Objective

Hepatocellular carcinima is one of the most common tumors in clinic and also one of the leading causes of death from cancer worldwide. Quercetin shows significant effects on blocking the development of various cancers.

Methods

We used the human hepatocellular carcinoma LM3 and nude mice tumor model to assess the effects of quercetin in hepatocellular carcinoma and clarify its mechanism of action. We collected LM3 cell line treated with different doses of quercetin at different time periods and determined the vital indexes. The liver tissues of mice were collected and used for western boltting (WB), Hematoxylin and Eosin (H&E) and TUNEL staining.

Results

Results indicated that quercetin suppressed the Hepatocellular carcinoma (HCC) growth both in vivo and in vitro. Quercetin could disturb LM3 cells proliferation and cell cycle distribution, thus inducing apoptosis. At the same time, quercetin inhibited LM3 cells migration and invasion and promoted HCC autophagy. These effects at least partly depended on the down‐regulation of the activation of JAK2 and STAT3 by quercetin.

Conclusion

Quercetin inhibited hepatocellular carcinoma progression by modulating cell apoptosis, migration, invasion, and autophagy; and its effects were at least partly related with the JAK2/STAT3 signaling pathway.

Ginsenoside compound K protects human umbilical vein endothelial cells against oxidized low-density lipoprotein-induced injury via inhibition of nuclear factor-κB, p38, and JNK MAPK pathways

Background

Oxidized low-density lipoprotein (ox-LDL) causes vascular endothelial cell inflammatory response and apoptosis and plays an important role in the development and progression of atherosclerosis. Ginsenoside compound K (CK), a metabolite produced by the hydrolysis of ginsenoside Rb1, possesses strong anti-inflammatory effects. However, whether or not CK protects ox-LDL-damaged endothelial cells and the potential mechanisms have not been elucidated.

Methods

In our study, cell viability was tested using a 3-(4, 5-dimethylthiazol-2yl-)-2,5-diphenyl tetrazolium bromide (MTT) assay. Expression levels of interleukin-6, monocyte chemoattractant protein-1, tumor necrosis factor-α, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 were determined by enzyme-linked immunosorbent assay and Western blotting. Mitochondrial membrane potential (ΔΨm) was detected using JC-1. The cell apoptotic percentage was measured by the Annexin V/ propidium iodide (PI) assay, lactate dehydrogenase, and caspase-3 expression. Apoptosis-related proteins, nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPK) signaling pathways protein expression were quantified by Western blotting.

Results

Our results demonstrated that CK could ameliorate ox-LDL-induced human umbilical vein endothelial cells (HUVECs) inflammation and apoptosis, NF-κB nuclear translocation, and the phosphorylation of p38 and c-Jun N-terminal kinase (JNK). Moreover, anisomycin, an activator of p38 and JNK, significantly abolished the anti-apoptotic effects of CK.

Conclusion

These results demonstrate that CK prevents ox-LDL-induced HUVECs inflammation and apoptosis through inhibiting the NF-κB, p38, and JNK MAPK signaling pathways. Thus, CK is a candidate drug for atherosclerosis treatment.

Inhibitory effect of trans-caryophyllene (TC) on leukocyte-endothelial attachment

trans-Caryophyllene (TC) is a major component found in the essential oils of many spices and foods/medicinal plants. It is a natural sesquiterpene and has been the subject of numerous studies. However, the effects of TC on vascular inflammation remain unknown. In this study, we reported that TC treatment in human umbilical vein endothelial cells (HUVECs) prevented attachment of monocytic leukemia cell line THP-1 cells to endothelial cells. In addition, in vivo results indicate that TC inhibited macrophage infiltration to the aortic surface and reduced total serum levels of cholesterol and triglycerides. Importantly, administration of TC could inhibit the induction of vascular cell adhesion molecule-1 (VCAM-1) both in vitro and in vivo. Notably, our data indicate that the inhibitory effects of TC on the expression of VCAM-1 are mediated by the JAK2/STAT1/IRF-1 pathway. TC is a specific agonist of the type 2 cannabinoid receptor (CB2R). Importantly, we further verified that the inhibitory effects of TC on the expression of IRF-1 and VCAM-1 are dependent on activation of CB2R. Inhibition of CB2R by either specific inhibitors or RNA interference abolished the inhibitory effects of TC on the expression of IRF-1 and VCAM-1. Our results suggest that TC might have a capacity to suppress the development of atherosclerosis.

Comparative effects of red and white grapes on oxidative markers and lipidemic parameters in adult hypercholesterolemic humans

The present study compared the effects of consuming red versus white whole grapes on oxidative and lipidemic indices in people with hypercholesterolemia. Sixty nine patients were randomized into three groups. The two treatment groups consumed 500 g of either Condori red grapes or Shahroodi white grapes daily for 8 weeks, and the third group served as a control. Plasma glucose, triacylglycerol (TG), cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), thiobarbituric acid reactive substances (TBARS) and total antioxidant capacity (TAC) were determined by colorimetric methods at baseline and at the end of the study. In addition, the polyphenol and fiber content of the two grape varieties was measured. TBARS was reduced in both study groups compared to the control group, and the reduction was greater in the group that consumed red grapes compared to the white grapes. TAC was increased significantly in both red and white grape consuming groups compared to the control group. Total cholesterol and LDL-C were decreased in the red grape group compared to the control group. No significant changes in fasting blood glucose, TG or HDL-C were observed among the groups. The results of this study suggest that consumption of the whole fruit of red grapes has more potent anti-oxidative and hypolipidemic effects compared to the white grapes in hyperlipidemic adult humans. Hence, the whole fruit of red grapes may be an excellent fruit choice not only to prevent oxidative stress related metabolic disorders but also cholesterol related cardiovascular diseases, particularly in hyperlipidemic adult humans.

EGCG attenuates atherosclerosis through the Jagged-1/Notch pathway

Atherosclerosis is the most common cause of cardiovascular diseases worldwide. Oxidized low-density lipoprotein (ox-LDL) is a particularly important risk factor in the pathogenesis of atherosclerosis. Accumulating evidence has indicated that epigallocatechin-3-gallate (EGCG; a catechin found in the popular beverage, greent tea) protects against ox-LDL-induced atherosclerosis. However, the underlying mechanisms remain unclear. In the present study, ox-LDL (100 mg/l) induced damage to, and the apoptosis of human umbilical vein endothelial cells (HUVECs) by reducing endothelial nitric oxide synthase (eNOS) expression and promoting inducible nitric oxide synthase (iNOS) expression; these effects were abrogated by the addition of 50 µM EGCG. Furthermore, ox-LDL rapidly activated the membrane translocation of p22phox, and altered the protein expression of Jagged-1 and Notch pathway-related proteins [Math1, hairy and enhancer of split (HES)1 and HES5]; these effects were also prevented by pre-treatment with 50 µM EGCG. In addition, Jagged-1 played a significant role in the EGCG-mediated protection against ox-LDL-induced apoptosis and ox-LDL‑diminished cell adhesion in the HUVECs. Finally, EGCG inhibited high-fat diet (HFD)-induced atherosclerosis in apolipoprotein E (ApoE) knockout (ApoE-KO) mice through the Jagged-1/Notch pathway. Taken together, these findings demonstrate that 50 µM EGCG protects against ox-LDL-induced endothelial dysfunction through the Jagged-1/Notch signaling pathway. Moreover, our data provide insight into the possible molecular mechanisms through which EGCG attenuates ox-LDL‑induced vascular endothelial dysfunction.

Effects of Flavonoids from Food and Dietary Supplements on Glial and Glioblastoma Multiforme Cells

Quercetin, catechins and proanthocyanidins are flavonoids that are prominently featured in foodstuffs and dietary supplements, and may possess anti-carcinogenic activity. Glioblastoma multiforme is the most dangerous form of glioma, a malignancy of the brain connective tissue. This review assesses molecular structures of these flavonoids, their importance as components of diet and dietary supplements, their bioavailability and ability to cross the blood-brain barrier, their reported beneficial health effects, and their effects on non-malignant glial as well as glioblastoma tumor cells. The reviewed flavonoids appear to protect glial cells via reduction of oxidative stress, while some also attenuate glutamate-induced excitotoxicity and reduce neuroinflammation. Most of the reviewed flavonoids inhibit proliferation of glioblastoma cells and induce their death. Moreover, some of them inhibit pro-oncogene signaling pathways and intensify the effect of conventional anti-cancer therapies. However, most of these anti-glioblastoma effects have only been observed in vitro or in animal models. Due to limited ability of the reviewed flavonoids to access the brain, their normal dietary intake is likely insufficient to produce significant anti-cancer effects in this organ, and supplementation is needed.

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.

Pro-oxidative and antioxidative controls and signaling modification of polyphenolic phytochemicals: contribution to health promotion and disease prevention?

Polyphenolic phytochemicals (PPs) have been extensively studied as potential nutriceuticals for maintenance of health and treatment of cancer, inflammation, and neurodegeneration. However, the reported beneficial outcomes are inconsistent. The biological activities of PPs have been attributed to their pro-oxidative and antioxidative actions and effects on signaling mechanisms and epigenomic modifications. These diversified properties were described or postulated on the basis of a variety of experimental studies using cell culture and animal models, even though most have not been replicated and results are not validated. This review attempts to give an overview of biological properties of PPs, based on the coherent results from relevant studies, and evaluate critically the experimental conditions and possible artifacts. Complicated molecular mechanisms and multitargeting genomic interactions of PPs are discussed, with a view that reasonable mechanistic propositions are usually obtained from well-designed in vivo studies.

SK-N-MC cell death occurs by distinct molecular mechanisms in response to hydrogen peroxide and superoxide anions: involvements of JAK2-STAT3, JNK, and p38 MAP kinases pathways

Oxidative stress plays a vital role in the pathogenesis of neurodegenerative diseases. Nerve cells are incessantly exposed to environmental stresses leading to overproduction of some harmful species like reactive oxygen species (ROS). ROS including hydrogen peroxide and superoxide anion are potent inducers of various signaling pathways encompassing MAPKs and JAK-STAT pathways. In the current study, we scrutinized the effects of hydrogen peroxide and/or menadione (superoxide anion generator) on JNK/p38-MAPKs and JAK2-STAT3 pathways to elucidate the mechanism(s) by which each oxidant modulated the above-mentioned pathways leading to SK-N-MC cell death. Our results delineated that hydrogen peroxide and superoxide anion radical induced distinct responses as we showed that STAT3 and p38 were activated in response to hydrogen peroxide, but not superoxide anion radicals indicating the specificity in ROS-induced signaling pathways activations and behaviors. We also observed that menadione induced JNK-dependent p53 expression and apoptotic death in SK-N-MC cells while H2O2-induced JNK activation was p53 independent. Thus, we declare that ROS type has a key role in selective instigation of JNK/p38-MAPKs and JAK2-STAT3 pathways in SK-N-MC cells. Identifying these differential behaviors and mechanisms of hydrogen peroxide and superoxide anion functions illuminates the possible therapeutic targets in the prevention or treatment of ROS-induced neurodegenerative diseases such as Alzheimer's disease.

Baicalein reduces lipopolysaccharide-induced inflammation via suppressing JAK/STATs activation and ROS production

OBJECTIVE

To investigate the precise molecular mechanisms by which baicalein exerts beneficial biochemical activities in RAW264.7 macrophages treated with LPS.

MATERIALS AND METHODS

RAW264.7 cells were cultured in the absence or presence of baicalein together with or without LPS. iNOS and COX-2 expression were measured by western blot and RT-PCR analyses. TNF-α, IL-1β, and IL-6 were determined by using double-antibody sandwich ELISA. Phosphorylations of JAK1 and JAK2, and of STAT1 and STAT3 were detected by western blotting. Nuclear translocation of STAT1 and STAT3 was visualized by confocal microscopy. ROS production was detected by ROS assay.

RESULTS

Baicalein significantly reduced the phosphorylation of STAT1 and STAT3 and the phosphorylation of JAK1 and JAK2, but without affecting MAPKs phosphorylation in LPS-stimulated RAW264.7 cells. Baicalein suppressed the nuclear translocation of STAT1 and STAT3 and inhibited production of iNOS upon LPS-stimulation, resulting in the inhibition of releases of NO and pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α, in a dose-dependent manner. In addition, we found that baicalein reduced the LPS-induced accumulation of ROS, confirming that baicalein serves as an antioxidant.

CONCLUSIONS

Our results suggested that suppressing JAK/STATs activation and interfering with ROS production might contribute to the anti-inflammatory action of baicalein in macrophages.

Dietary flavonoids and the development of type 2 diabetes and cardiovascular diseases: review of recent findings

PURPOSE OF REVIEW

This review summarizes the results on flavonoid intakes and the development of type 2 diabetes and cardiovascular diseases.

RECENT FINDINGS

Recent advances in food composition databases have allowed the evaluation of a more comprehensive range of flavonoids in epidemiological studies. In addition, the number of randomized trials of flavonoid-rich foods has increased rapidly. Results from both cohort studies and randomized trials suggest that anthocyanidins from berries and flavan-3-ols from green tea and cocoa may lower the risk of type 2 diabetes and cardiovascular diseases. Meta-analyses of randomized trials indicate that the strongest evidence exists for a beneficial effect of green tea on LDL-cholesterol and a beneficial effect of flavan-3-ol-rich cocoa on endothelial function and insulin sensitivity. Few randomized trials had a long duration or evaluated pure flavonoid compounds.

SUMMARY

Evidence from cohort studies and randomized trials suggest beneficial effects of food sources of anthocyanidins (berries) and flavan-3-ols (green tea and cocoa) on cardiovascular health. These findings need to be confirmed in long-term randomized trials, and evaluation of pure compounds will be important to establish what specific flavonoids and doses are effective.

Glycoxydation promotes vascular damage via MAPK-ERK/JNK pathways

Oxidation and glycation enhance foam cell formation via MAPK/JNK in euglycemic and diabetic subjects. Here, we investigated the effects of glycated and oxidized LDL (glc-oxLDL) on MAPK-ERK and JNK signaling pathways using human coronary smooth muscle cells. Glc-oxLDL induced a broad cascade of MAPK/JNK-dependent signaling transduction pathways and the AP-1 complex. In glc-oxLDL treated coronary arterioles, tumor necrosis factor (TNF) α increased JNK phosphorylation, whereas protein kinase inhibitor dimethylaminopurine (DMAP) prevented the TNF-induced increase in JNK phosphorylation. The role of MKK4 and JNK were then investigated in vivo, using apolipoprotein E knockout (ApoE(-/-)) mice. Peritoneal macrophages, isolated from spontaneously hyperlipidemic but euglycemic mice showed increases in both proteins and phosphorylated proteins. Compared to streptozotocin-treated diabetic C57BL6 and nondiabetic C57BL6 Wt mice, in streptozotocin-diabetic ApoE(-/-) mice, the increment of foam cell formation corresponded to an increment of phosphorylation of JNK1, JNK2, and MMK4. Thus, we provide a first line of evidence that MAPK-ERK/JNK pathways are involved in vascular damage induced by glycoxidation.

Differential suppression of intracellular reactive oxygen species-mediated signaling pathway in vascular endothelial cells by several subclasses of flavonoids

Increased intracellular reactive oxygen species (ROS) is crucial for vascular endothelial dysfunction, a key step in the initiating of atherosclerosis (AS). The antioxidant activity of flavonoids has been suggested to contribute to AS prevention. However, The association of the structure characteristics to antioxidant capacities in relation to the inhibitory effects on endothelial dysfunction has not been well established. In this study, four subclasses of flavonoids with similar structures, including two anthocyanins (delphinidin and cyanidin), two flavonols (myricetin and quercetin), two flavones (luteolin and apigenin) and two isoflavones (genistein and daidzein) were examined for their inhibitory effects on intracellular ROS-mediated signaling pathway in the human umbilical vein endothelial cell EA.hy926. Cells were pretreated with different flavonoids for 2 h and then exposed to oxLDL of 100 μg/ml for another 24 h. It was found that treatment with different flavonoids alone had no notable effects on cell viability. However, the oxLDL-induced decrease of cell viability, generation of O(2)(·-) and ROS, p38MAPK activation, NF-κB nuclear translocation, NF-κB-modulated transcriptional activity as well as the mRNA expression of genes including ICAM-1, VCAM-1, E-selectin, MMP-1, MMP-2 and MMP-9 were notably inhibited by the pretreatment of different flavonoids through blunting ROS-triggered signaling pathway, in spite of apparent differences. And the number of hydroxyl groups in total, 3',4'-ortho-dihydroxyl in B-ring and 3-hydroxyl group in C-ring of flavonoids were important structure characteristics for the inhibitory effects. Thus, anthocyanins and flavonols such as delphinidin and myricetin exert higher ROS scavenging activities and more significant endothelium-protective effects compared to the other compounds. Our results provide evidence for AS prevention and a basis for designing the potent anti-atherosclerotic agents.

Platelets and atherogenesis: Platelet anti-aggregation activity and endothelial protection from tomatoes (Solanum lycopersicum L.)

In recent years, it has been shown that platelets are not only involved in the arterial thrombotic process, but also that they play an active role in the inflammatory process of atherogenesis from the beginning. The interaction between platelets and endothelial cells occurs in two manners: activated platelets unite with intact endothelial cells, or platelets in resting adhere to activated endothelium. In this context, inhibition of the platelet function (adhesion/aggregation) could contribute to the prevention of atherothrombosis, the leading cause of cardiovascular morbidity. This can be achieved with antiplatelet agents. However, at the public health level, the level of primary prevention, a healthy diet has also been shown to exert beneficial effects. Among those elements of a healthy diet, the consumption of tomatoes (Solanum lycopersicum L.) stands out for its effect on platelet anti-aggregation activity and endothelial protection, which may be beneficial for cardiovascular health. This article briefly discusses the involvement of platelets in atherogenesis and the possible mechanisms of action provided by tomatoes for platelet anti-aggregation activity and endothelial protection.

Theaflavin, a black tea polyphenol, protects nigral dopaminergic neurons against chronic MPTP/probenecid induced Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder, characterized by loss of dopominergic neurons in substantia nigra pars compacta, and can be experimentally induced by the neurotoxin 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). Chronic administration of MPTP/probenecid (MPTP/p) leads to oxidative stress, induction of apoptosis, and loss of dopominergic neurons which results in motor impairments. Epidemiological studies have shown an inverse relationship between tea consumption and susceptibility to PD. Theaflavin is a black tea polyphenol, which possess a wide variety of pharmacological properties including potent anti oxidative, anti apoptotic and anti inflammatory effects. The current study is aimed to assess the effect of theaflavin against MPTP/p induced neurodegenaration in C57BL/6 mice. We found that the theaflavin attenuates MPTP/p induced apoptosis and neurodegeneration as evidenced by increased expression of nigral tyrosine hydroxylase (TH), dopamine transporter (DAT) and reduced apoptotic markers such as caspase-3, 8, 9 accompanied by normalized behavioral characterization. This may be due to anti oxidative and anti apoptotic activity and these data indicate that theaflavin may provide a valuable therapeutic strategy for the treatment of progressive neurodegenerative diseases such as PD.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

Isoangustone A suppresses mesangial fibrosis and inflammation in human renal mesangial cells

Development of diabetic nephropathy with fibrosis is associated with hypereglycemia-linked inflammation. Increased levels of proinflammatory factors have been found in diabetic patients with nephropathy. The present study was to test the hypothesis that isoangustone A, a novel compound present in licorice, can inhibit renal fibrosis and inflammation inflamed by high glucose (HG) in human mesangial cells through disturbing transforming growth factor β (TGF- β) and nuclear facor κB (NF- κB) pathways. Serum-starved mesangial cells were cultured in 33 mmol/L glucose media. Cells were treated with 1–20 μmol/L isoangustone A isolated from Glycyrrhiza uralensis licorice for three days. Exposure of cells to HG elevated connective tissue growth factor and collagen production, which was dose-dependently reversed by isoangustone A. Isoangustone A boosted HG-plummeted membrane type matrix metalloproteinase (MMP)-1 expression and diminished HG-elevated tissue inhibitor of MMP-2 expression. HG activated mesangial TGF- β1-SMAD-responsive signaling, which was repealed by ≥10 μmol/L isoangustone A. Furthermore, HG upregulated intracellular cell adhesion molecule-1 (ICAM-1) level and monocyte chemoattractant protein-1 (MCP-1) mRNA expression, and such increases were dose-dependently suppressed by isoangustone A most likely through hampering TGF- β signaling pathways. Blockade of NF- κB signaling appeared to be responsible for attenuating HG-triggered induction of ICAM-1 and MCP-1. Our findings provide the first evidence that isoangustone A dampens mesangial sclerosis associated with inflammation in response to HG through hindering TGF- β and NF- κB signaling.

Antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation

Oxidized low-density lipoproteins (oxLDL) play a critical role in the initiation of atherosclerosis through activation of inflammatory signaling. In the present work we investigated the role of antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation. Significant decrease in intracellular NO level and superoxide overproduction was found in human umbilical vein endothelial cells (HUVEC) treated with oxLDL, but not with LDL. The redox imbalance was prevented by the addition of quercetin or resveratrol. Expression analysis of 14 genes associated with oxidative stress and inflammation revealed oxLDL-mediated up-regulation of genes specifically involved in leukocyte recruitment and adhesion. This up-regulation could be partially avoided by the addition of verbascoside or resveratrol, while treatment with quercetin resulted in a further increase in the expression of these genes. Lipopolysaccharide (LPS)-treated HUVEC were also used for the evaluation of anti-inflammatory potency of plant polyphenols. Significant differences between HUVEC treaded with oxLDL and LPS were found in both the expression pattern of inflammation-related genes and the effects of plant polyphenols on cellular responses. The present data indicate that plant polyphenols may affect vascular inflammation not only as antioxidants but also as modulators of inflammatory redox signaling pathways.

Anthocyanins in cardiovascular disease

Anthocyanins are a group of abundant and widely consumed flavonoid constituents that occur ubiquitously in the plant kingdom, providing the bright red-orange to blue-violet colors present in many fruit- and vegetable-based food products. Their intake has been estimated to be up to 9-fold higher than that of other dietary flavonoids. Anthocyanins have become increasingly important to the food industry as their use as natural alternatives to artificial colors has become widespread and knowledge of their health-promoting properties has become more evident. Epidemiological studies suggest that increased consumption of anthocyanins lowers the risk of cardiovascular disease (CVD), the most common cause of mortality among men and women. Anthocyanins frequently interact with other phytochemicals, exhibiting synergistic biological effects but making contributions from individual components difficult to decipher. Over the past 2 decades, many peer-reviewed publications have demonstrated that in addition to their noted in vitro antioxidant activity, anthocyanins may regulate different signaling pathways involved in the development of CVD. This review summarizes the latest developments on the bioavailability/bioactivity and CVD preventative activities of anthocyanins, including results from in vitro cell culture and in vivo animal model systems as related to their multiple proposed mechanisms of action. Limited yet promising data from epidemiological studies and human clinical trials are also presented. Future studies aimed at enhancing the absorption of anthocyanins and characterizing their metabolic and/or breakdown products are necessary to ultimately evaluate their use for protection/prevention against the development of CVD.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.

Chrysin suppresses IL-6-induced angiogenesis via down-regulation of JAK1/STAT3 and VEGF: an in vitro and in ovo approach

Chrysin, 5,7-dihydroxyflavone, possesses many biologic properties. This study aimed to investigate the effects and molecular mechanisms of chrysin on IL-6-induced angiogenesis in vitro and in ovo. Chicken chorioallantoic membrane assay, an in ovo angiogenesis assay, showed chrysin significantly suppressed IL-6-induced neovascularization. Furthermore, chrysin significantly suppressed human umbilical vein endothelial cell (HUVECs) migration and tube formation. The signaling pathway involved in chrysin-related antiangiogenesis was also investigated. The data indicated that chrysin is able to down-regulate the expression of glycoprotein 130 (gp130), soluble IL-6 receptor (IL-6R), phosphorylated JAK1 and STAT3, and VEGF in HUVECs. The IL-6-induced binding of STAT3 was significantly suppressed by chrysin. Moreover, chrysin did not further suppress VEGF expression with STAT3 knocked down. Taken together, the results show that chrysin suppresses IL-6-induced angiogenesis through modulation of the sIL-6R/gp130/JAK1/STAT3/VEGF signaling pathway. Chrysin may provide new therapeutic potential for IL-6-induced pathological angiogenesis.

EGCG protects against oxidized LDL-induced endothelial dysfunction by inhibiting LOX-1-mediated signaling

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), originally identified as the major receptor for oxidized low-density lipoprotein (oxLDL) in endothelial cells, plays a major role in the pathology of vascular diseases. Green tea consumption is associated with reduced cardiovascular mortality in some epidemiological studies. In the present study, we hypothesized that the most abundant polyphenolic compound in tea, epigallocatechin-3-gallate (EGCG), can downregulate parameters of endothelial dysfunction by modulating LOX-1-regulated cell signaling. In cultured human umbilical vein endothelial cells (HUVECs), exposure to oxLDL (130 microg/ml), which led to an increase in LOX-1 expression at the RNA and protein levels, was abrogated by addition of EGCG or DPI, a well-known inhibitor of flavoproteins, suggesting the involvement of NADPH oxidase. Furthermore, oxLDL rapidly activated the membrane translocation of Rac-1 and p47phox and the subsequent induction of ROS generation, which was suppressed markedly by pretreatment with EGCG or anti-LOX-1 monoclonal antibody. OxLDL also increased p38 MAPK phosphorylation and decreased phosphorylation of the amino-terminal region of Akt, with maximal induction at about 30 min, and NF-kappaB phosphorylation within 1 h, resulting in redox-sensitive signaling. In addition, oxLDL diminished the expression of endothelial nitric oxide synthase (eNOS), enhanced the expression of endothelin-1 and adhesion molecules (ICAM, E-selectin, and monocyte chemoattractant protein-1), and increased the adherence of monocytic THP-1 cells to HUVECs. Pretreatment with EGCG, however, exerted significant cytoprotective effects in all events. These data suggest that EGCG inhibits the oxLDL-induced LOX-1-mediated signaling pathway, at least in part, by inhibiting NADPH oxidase and consequent ROS-enhanced LOX-1 expression, which contributes to further ROS generation and the subsequent activation of NF-kappaB via the p38 MAPK pathway. Results from this study may provide insight into a possible molecular mechanism by which EGCG suppresses oxLDL-mediated vascular endothelial dysfunction.

Bog blueberry anthocyanins alleviate photoaging in ultraviolet-B irradiation-induced human dermal fibroblasts

Fruits of bog blueberry (Vaccinium uliginosum L.) are rich in anthocyanins that contribute pigmentation. Anthocyanins have received much attention as agents with potentials preventing chronic diseases. This study investigated the capacity of anthocyanin-rich extract from bog blueberry (ATH-BBe) to inhibit photoaging in UV-B-irradiated human dermal fibroblasts. BBe anthocyanins were detected as cyanidin-3-glucoside, petunidin-3-glucoside, malvidin-3-glucoside, and delphinidin3-glucoside. ATH-BBe attenuated UV-B-induced toxicity accompanying reactive oxygen species (ROS) production and the resultant DNA damage responsible for activation of p53 and Bad. Preincubation of ATH-BBe markedly suppressed collagen degradation via blunting production of collagenolytic matrix metalloproteinases (MMP). Additionally, ATH-BBe enhanced UV-B-downregulated procollagen expression at transcriptional levels. We next attempted to explore whether ATH-BBe mitigated the MMP-promoted collagen degradation through blocking nuclear factor kappaB (NF-kappaB) activation and MAPK-signaling cascades. UV-B radiation enhanced nuclear translocation of NF-kappaB, which was reversed by treatment with ATH-BBe. The UV-B irradiation rapidly activated apoptosis signal-regulating kinase-1 (ASK-1)-signaling cascades of JNK and p38 mitogen-activated protein kinase (p38 MAPK), whereas ATH-BBe hampered phosphorylation of c-Jun, p53, and signal transducers and activators of transcription-1 (STAT-1) linked to these MAPK signaling pathways. ATH-BBe diminished UV-B augmented-release of inflammatory interleukin (IL)-6 and IL-8. These results demonstrate that ATH-BBe dampens UV-B-triggered collagen destruction and inflammatory responses through modulating NF-kappaB-responsive and MAPK-dependent pathways. Therefore, anthocyanins from edible bog blueberry may be protective against UV-induced skin photoaging.

Diabetes mellitus and apoptosis: inflammatory cells

Since the early observation that similarities between thyroiditis and insulitis existed, the important role played by inflammation in the development of diabetes has been appreciated. More recently, experiments have shown that inflammation also plays a prominent role in the development of target organ damage arising as complications, with both elements of the innate and the adaptive immune system being involved, and that cytokines contributing to local tissue damage may arise from both infiltrating and resident cells. This review will discuss the experimental evidence that shows that inflammatory cell-mediated apoptosis contributes to target organ damage, from beta cell destruction to both micro- and macro-vascular disease complications, and also how alterations in leukocyte turnover affects immune function.

Protective effects of a benzoxazine derivative against oxidized LDL-induced apoptosis and the increases of integrin beta4, ROS, NF-kappaB and P53 in human umbilical vein endothelial cells

To investigate whether 6-amino-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine (ABO) inhibits oxidized low-density lipoprotein (oxLDL)-induced human umbilical vein endothelial cell (HUVEC) apoptosis, we treated HUVECs with oxLDL in the absence or presence of ABO. The results showed that ABO could act as an effective inhibitor of oxLDL-elicited HUVEC apoptosis by inhibiting the levels of integrin beta4, reactive oxygen species (ROS), NF-kappaB and P53, and suppressing NF-kappaB nuclear translocation.

Blockade of oxidized LDL-triggered endothelial apoptosis by quercetin and rutin through differential signaling pathways involving JAK2

Oxidized LDL is highly atherogenic, as it stimulates foam cell formation and promotes inflammatory and thrombotic processes. The present study elucidated whether the antioxidants quercetin and its rutinoside rutin exert antiapoptosis in endothelial cells exposed to Cu(2+)-oxidized LDL. Quercetin and rutin inhibited the oxidized LDL-induced endothelial toxicity at nontoxic doses of </=25 muM with an inhibition of intracellular oxidant accumulation. These effects accompanied disappearance of apoptotic bodies and suppression of caspase-3 activation. Additionally, condensed nuclei vanished in oxidized LDL-exposed cells treated with quercetin and rutin. This study further explored whether such effects were achieved by redox manipulation via JAK2-STAT3-responsive death/survival signaling pathways involving multiple MAPK. Unlike quercetin, rutin blocked the activation of oxidized LDL-induced JNK and p38 MAPK as well as the upstream ASK1 phosphorylation. Quercetin dose-dependently attenuated the JAK2 phosphorylation evoked by oxidized LDL, whereas rutin abolished the JAK signaling accompanying nuclear transactivation of STAT3 and enhanced the JAK activity-inhibiting SOCS3 expression. Conversely, oxidized LDL-induced IL-6 release was minimal for the JAK2 activation, although this effect was counteracted by quercetin and rutin. These results suggest that quercetin and rutin inhibit Cu(2+)-oxidized LDL-induced endothelial apoptosis through modulating JAK2-STAT3 pathways and that rutin may modulate a signaling crosstalk between JAK2 and MAPK.