Chenghui Xie

The açaí flavonoid velutin is a potent anti-inflammatory agent: blockade of LPS-mediated TNF-α and IL-6 production through inhibiting NF-κB activation and MAPK pathway

Recent studies have shown that some flavonoids are modulators of proinflammatory cytokine production. In this study, velutin, a unique flavone isolated from the pulp of açaí fruit (Euterpe oleracea Mart.), was examined for its effects in reducing lipopolysaccharide-induced proinflammatory cytokine tumor necrosis factor (TNF)-α and interleukin (IL)-6 production in RAW 264.7 peripheral macrophages and mice peritoneal macrophages. Three other structurally similar and well-studied flavones, luteolin, apigenin and chrysoeriol, were included as controls and for comparative purposes. Velutin exhibited the greatest potency among all flavones in reducing TNF-α and IL-6 production. Velutin also showed the strongest inhibitory effect in nuclear factor (NF)-κB activation (as assessed by secreted alkaline phosphatase reporter assay) and exhibited the greatest effects in blocking the degradation of inhibitor of NF-κB as well as in inhibiting mitogen-activated protein kinase p38 and JNK phosphorylation; all of these are important signaling pathways involved in production of TNF-α and IL-6. The present study led to the discovery of a strong anti-inflammatory flavone, velutin. This compound effectively inhibited the expression of proinflammatory cytokines TNF-α and IL-6 in low micromole levels by inhibiting NF-κB activation and p38 and JNK phosphorylation.

Dietary Blueberries Attenuate Atherosclerosis in Apolipoprotein E-Deficient Mice by Upregulating Antioxidant Enzyme Expression

Protective effects of blueberries (BB) against atherosclerosis and potential underlying mechanisms in reducing oxidative stress were examined in apoE-deficient (apoE(-/-)) mice. ApoE(-/-) mice were fed an AIN-93G diet (CD) or CD formulated to contain 1% freeze-dried whole BB for 20 wk. The mean lesion area for apoE(-/-) mice fed BB was reduced by 39% (P < 0.001) in the aorta sinus and 58% (P < 0.001) in the descending aorta compared with CD-fed mice. These atheroprotective effects were independent of the serum lipid profile or total antioxidant capacity (as measured by oxygen radical absorbance capacity). The concentration of a biomarker of lipid peroxidation, F(2)-isoprostane, was lower in liver of BB-fed mice (P < 0.05). Genes analyzed by RT-PCR array showed that 4 major antioxidant enzymes in aorta [superoxide dismutase (SOD) 1, SOD2, glutathione reductase (GSR), and thioredoxin reductase 1] were upregulated in BB-fed mice. Enzyme activities of SOD and GSR were greater (P < 0.05) in liver and/or serum of BB-fed mice than those of CD-fed mice. In addition, serum paraoxonase 1 activity in serum of BB-fed mice was also greater than that of CD-fed mice (P < 0.05) at the end of the study. These results suggest a protective effectiveness of BB against atherosclerosis in this apoE(-/-) mouse model. The potential mechanisms may involve reduction in oxidative stress by both inhibition of lipid peroxidation and enhancement of antioxidant defense.

Blueberries reduce pro-inflammatory cytokine TNF-α and IL-6 production in mouse macrophages by inhibiting NF-κB activation and the MAPK pathway.

Blueberries (BB) have been reported to attenuate atherosclerosis in apoE-deficient (ApoE(-/-) ) mice. The aim of this study was to evaluate the effects of BB in reducing pro-inflammatory cytokine production in mouse macrophages. ApoE(-/-) mice were fed AIN-93G diet (CD) or CD formulated to contain 1% freeze-dried BB for 5 wk. TNF-α and IL-6 were lower in serum of BB-fed mice and TNF-α expression in aorta was down-regulated with BB feeding. Protein level and mRNA expression of TNF-α and IL-6 were significantly lower in the peritoneal macrophages from mice fed BB without or with LPS or oxLDL stimulation. RAW264.7 macrophages were treated with polyphenol-enriched extracts made from the sera of rats fed CD (SEC) or CD containing 10% BB (SEB). SEB significantly inhibited LPS-induced mRNA expression and protein levels of TNF-α and IL-6. Furthermore, SEB inhibited the phosphorylation of IκB, NF-κB p65, MAPK p38 and JNK. All of these are important signaling pathways involved in the production of TNF-α and IL-6.

Acaí juice attenuates atherosclerosis in ApoE deficient mice through antioxidant and anti-inflammatory activities

OBJECTIVE Açaí fruit pulp has received much attention because of its high antioxidant capacity and potential anti-inflammatory effects. In this study, athero-protective effects of açaí juice were investigated in apolipoprotein E deficient (apoE(-/-)) mice. METHODS AND RESULTS ApoE(-/-) mice were fed AIN-93G diet (CD) or CD formulated to contain 5% freeze-dried açaí juice powder (AJ) for 20 weeks. The mean lesion areas in the aorta for apoE(-/-) mice fed AJ were 58% less (P<0.001) compared to that for CD fed mice. HDL-cholesterol was higher in AJ fed mice. Biomarkers of lipid peroxidation, including F(2)-isoprostanes and isomers of hydroxyoctadecadienoic acids and hydroxyeicosatetraenoic acids were significantly lower in serum and in liver of AJ fed mice. Expression of the two antioxidant enzyme genes, Gpx3 and Gsr, were significantly up-regulated in the aorta from AJ fed mice. The activity of GPX, GSR and PON1 increased in serum and/or liver of mice fed AJ. In the second experiment, ApoE(-/-) mice were fed CD or AJ for 5 weeks. Serum levels, gene expression and protein levels of the two proinflammatory cytokines TNF-α and IL-6 in the resident macrophages with or without LPS stimulation were lower in mice fed AJ. SEAP reporter assay determined that AJ reduced NF-κB activation. CONCLUSION Reducing lipid peroxidation through boosting antioxidant enzymes and inhibiting pro-inflammatory cytokine production are proposed as major underlying mechanisms for the athero-protective effects of the açaí juice tested in these experimental in vivo models.

Biflavonoids from Caper (Capparis spinosa L.) fruits and their effects in inhibiting NF-kappa B activation.

Caper (Capparis spinosa L.) fruits have been widely used as food and folk medicine in the Mediterranean basin and in central and west Asia. In this study, two biflavonoids, isoginkgetin, and ginkgetin, together with three other flavonoids, were isolated from caper fruits. Their chemical structures were elucidated by spectroscopic analyses and comparison with literature. To our knowledge, isoginkgetin, ginkgetin and sakuranetin were identified in caper for the first time. Notably, it is also the first time that biflavonoids have ever been found in the Capparidaceae. Concentrations of the two biflavonoids were measured in caper fruits collected from four major growing areas in northwest China. The anti-inflammatory effects of the flavonoids from caper fruits were evaluated by secreted placental alkaline phosphatase (SEAP) reporter assay, which was designed to measure nuclear factor-kappa B (NF-κB) activation. Isoginkgetin and ginkgetin showed inhibitory effects in initial screen at 20 μM, while the effect of ginkgetin was much greater than that of isoginkgetin. In a dose-response experiment, the IC(50) value of ginkgetin was estimated at 7.5 μM, suggesting it could be a strong NF-κB inhibitor and worthy of study in vivo.

Phenolic acids are in vivo atheroprotective compounds appearing in the serum of rats after blueberry consumption.

Blueberries (BB) have recently been shown to have cardioprotective effects and to prevent atherosclerosis in rodent models. However, the bioactive compounds in BB responsible for these effects have not yet been characterized. Seven phenolic acids (7PA) were identified as metabolites in the serum of rats fed diets supplemented with 10% freeze-dried BB. In this study, 7PA were evaluated for their potential atheroprotective effects in murine macrophage cell line RAW 264.7. 7PA were found to inhibit LPS-induced mRNA expression and protein levels of pro-inflammatory cytokine TNF-α and IL-6 by reducing MAPK JNK, p38, and Erk1/2 phosphorylation. After treatment with 7PA for 2 weeks, mRNA expression and protein levels of scavenger receptor CD36 were decreased (P<0.05), whereas type A scavenger receptor (SR-A) remained unchanged. Moreover, foam cell formation induced by oxLDL and oxLDL binding to macrophages was also inhibited by 7PA. In addition, 7PA increased (P<0.05) expression and protein levels of ATP-binding cassette transporter A1 (ABCA1), which facilitates cholesterol efflux and reduces cholesterol accumulation in macrophages. In summary, the present study demonstrates that certain phenolic acids are potential in vivo atheroprotective compounds following BB consumption in the rodent model. Because BB contain many phytochemicals, other as yet unidentified bioactive compounds may also be important in preventing atherosclerosis in this model and, possibly, in humans.

OxLDL or TLR2-induced cytokine response is enhanced by oxLDL-independent novel domain on mouse CD36

OxLDL binding to CD36 is shown to result in macrophage activation and foam cell formation that have been implicated in atherosclerosis. However, CD36 has also been shown to induce inflammatory response to other ligands besides oxLDL. During the course of blocking CD36 oxLDL binding function using anti CD36 antibodies, we have identified a novel domain of CD36 that triggers inflammatory response-independent of oxLDL binding. OxLDL bound to the mouse reporter cell line RAW-Blue induced TNF-α and RANTES mRNA and protein expression. Pretreatment of RAW-Blue cells with an anti-mCD36 mAb, JC63.1, an activating mCD36 mAb, surprisingly did not inhibit oxLDL-induced response. Further, binding of this antibody to CD36 alone induced a pro-inflammatory cytokine response in RAW-Blue cells as well as primary mouse macrophages. The induction of cytokine response was specific only to this antibody and was CD36-dependent, since CD36(-/-) macrophages failed to induce a similar response. The interaction of the antibody to CD36 led to activation of NF-κB and MAP kinase. Notably, a CD36 peptide blocked oxLDL-induced foam cell formation and macrophage activation. However, the activating mCD36 mAb induced macrophage activation was not inhibited by CD36 peptide. Further, activating mCD36 mAb enhanced oxLDL- or TLR2- or TLR4-mediated inflammatory responses. Collectively, our data provide evidence that activating mCD36 mAb binds to a domain different from the oxLDL-binding domain on mouse CD36, and suggest that interaction at this domain may contribute to oxLDL-independent macrophage inflammatory responses that lead to chronic inflammatory diseases.