Oxidized phospholipids as triggers of inflammation in atherosclerosis

Chronic inflammatory diseases including atherosclerosis are major causes of morbidity and mortality worldwide. However, the factors, which trigger processes that determine the outcome of an inflammatory response, are still poorly understood. Accumulating evidence suggests that certain lipid oxidation products, such as oxidized phospholipids (OxPL), may represent endogenously formed factors that are capable of triggering vascular inflammation. This review will address important questions regarding mechanisms involved in acute and chronic inflammation, and discuss the role of OxPL as key players in triggering the inflammatory response in atherosclerosis. Better understanding of how OxPL contribute to vascular inflammation should lead to new strategies in the treatment of chronic inflammatory disorders.     

不同pH对嗜酸乳杆菌分选酶相关基因表达及菌体黏附能力的影响

为探究嗜酸乳杆菌在小肠中黏附调控机制,嗜酸乳杆菌黏附与细胞壁分选酶及其相关蛋白的基因表达之间的关系。实验构建体外模型研究了不同p H培养条件下嗜酸乳杆菌的黏附能力、测定了分选酶基因和分选酶相关蛋白基因相对表达差异。实验结果表明:在p H5.5~7.5培养条件下,随着p H升高嗜酸乳杆菌菌体黏附性显著增加,srt基因及其相关蛋白的基因表达量显著上调。研究结果为p H对嗜酸乳杆菌的黏附效应的影响机制提供了相关理论依据。      

Diallyl disulphide,but not diallyl sulphide,increases leucocyte function-associated antigen-1 expression and cellular adhesion in monocytes

A steam distillation process at pH 9 was conducted to prepare garlic oil for food supplement. A garlic oil predominant in bioactive diallyl monosulphide (8.9%), diallyl disulphide (56.9%) diallyl trisulphide (7.6%) and diallyl tetrasulphide (2.6%) was obtained from peeled garlic cloves. The adhesion molecule leucocyte function-associated antigen-1 (LFA-1) mediates leucocyte adhesion and migration during immune responses. In this study, we investigated the effects of diallyl sulphide (DAS) and diallyl disulphide (DADS) on LFA-1 expression, cell adhesion and migration in the U937 and peritoneal macrophages from mice. After treatment, DADS, but not DAS, elevated the expression of LFA-1 in a dose- and time-dependent manner in U937 cells and peritoneal macrophages. Moreover, LFA-1 and intracellular adhesion molecular-1 (ICAM-1)-mediated adhesion also was increased by DADS in a dose- and time-dependent manner. After DADS treatment, LFA-1 clustering also increased on U937 surface. In contrast, there was no significant difference in migration of U937 cells between DADS treatment and no treatment. This study indicates the DADS, but not DAS, regulates immune responses by modulating LFA-1 expression, clustering and LFA-1-mediated adhesion in monocytes, evidences that DADS acts as an immune regulator of adhesion molecules during immune responses.     

Formation of zein nanoparticles by electrohydrodynamic atomization: Effect of the main processing variables and suitability for encapsulating the food coloring and active ingredient curcumin

Nanoparticles with a compact spherical structure and a narrow size distribution were prepared from a zein protein polymer by electrohydrodynamic atomization. The effects of key parameters of the process (polymer concentration, flow rate and applied voltage) on the size and morphology of the particles was studied. Zein nanoparticles could be obtained from zein concentrations ranging from 2.5% to 15% (w/w). The sizes of these particles, ranging from 175 to 900 nm, increased with increasing polymer concentration. Compact nanostructures were obtained for 2.5% and 5% zein solutions whereas 10% and 15% solutions yielded collapsed and shrunken particles. Flow rate also exerted an effect, the lower the flow rate the smaller the nanoparticles. The morphology of the nanoparticles did not change after incorporating curcumin in proportions ranging from 1:500 to 1:10 (curcumin:zein), and the encapsulation efficiency was around 85–90%. Fluorescence microscopy images showed that the nanostuctures obtained took the form of matrix systems with the curcumin homogeneously distributed in the zein matrix. The curcumin remained in the amorphous state in the nanoparticle, as revealed by X-Ray diffractometry, evidencing intimate contact with the polymer. After three months of storage at 23 °C and 43% relative humidity in the dark, neither the size or the morphology of the nanoparticles had undergone significant changes, nor had the curcumin content altered. Thanks to encapsulation, the curcumin presented good dispersion in an aqueous food matrix: semi-skimmed milk.     

荧光光谱法结合分子对接探究pH对姜黄素与牛血清白蛋白结合的影响

目的 采用荧光光谱法结合分子对接探究姜黄素(curcumin,CUR)与牛血清白蛋白(bovine serum albumin,B SA)在不同pH条件下相互作用。方法 通过荧光光谱法计算结合常数和热力学参数分析CUR对BSA荧光猝灭作用和机制;采用位点Marker和分子对接分析结合位点。结果 CUR与BSA结合形成了复合物,产生内源性荧光猝灭作用,属于静态猝灭。不同pH条件下的结合作用力不同,但结合位点数目均为1。由同步荧光可知,色氨酸残基附近疏水性增强,说明与CUR结合后BSA构象出现了收缩,结合位点靠近色氨酸。位点Marker实验证明pH影响CUR与BSA结合位点,分子对接结果表明, pH 7.4时CUR与BSA的结合位点位于Sudlow’s site I附近。结论 本研究表明pH影响CUR与BSA的结合反应,为CUR的活性保护及蛋白基递送载体研究提供理论支持。     

Geraniin-mediated apoptosis by cleavage of focal adhesion kinase through up-regulation of Fas ligand expression in human melanoma cells

Geraniin, a form of tannin separated from geranium, causes cell death through induction of apoptosis; however, cell death characteristics for geraniin have not yet been elucidated. Here, we investigated the mechanism of geraniin-induced apoptosis in human melanoma cells and demonstrated that geraniin was able to induce cell apoptosis in a concentration- and time-dependent manner. We also examined the signaling pathway related to geraniin-induced apoptosis. To clarify the relationship between focal adhesion kinase (FAK) and geraniin-induced apoptosis, we treated human melanoma cells with geraniin and found that this resulted dose- and time-dependent degradation in FAK. However, FAK cleavage was significantly inhibited when cells were pretreated with a selective inhibitor of caspase-3 (Ac-Asp-Glu-Val-Asp-CHO). Here, we demonstrated for the first time that geraniin triggered cell death by caspase-3-mediated cleavage of FAK. There were two possible mechanisms for activating caspase-3, mitochondria-mediated and receptor-mediated apoptosis. To confirm the geraniin-relevant signaling pathway, using immunoblot analysis we found that geraniin-induced apoptosis was associated with the up-regulation of Fas ligand expression, the activation of caspase-8, the cleavage of Bid, and the induction of cytochrome c release from mitochondria to the cytosol. Treatment with geraniin caused induction of caspase-3 activity in a dose- and time-dependent manner followed by proteolytic cleavage of poly-(ADP-ribose) polymerase, and DNA fragmentation factor 45. The geraniin-induced apoptosis may provide a pivotal mechanism for its cancer-chemopreventive action.     

Synthesis and chemical characterisation of curcuminoid colouring principles for their potential use as HPLC standards for the determination of curcumin colour in foods

The three major colour principles of curcumin have been synthesized, purified and chemically characterized using nuclear magnetic resonance spectroscopy, absorption spectroscopy, high- performance liquid chromatography and liquid chromatography-mass spectrometry. System suitability criteria for the simultaneous determination of the curcuminoids and annatto colorant (bixin and norbixin) by HPLC are presented and the importance of the water content of sample extracts discussed. The results show that synthetic curcuminoids may be synthesized with sufficient purity for use as standards for HPLC analysis provided that both the spectrophotometric and chromatographic purities are known. The potential for their use in the determination of turmeric and/or added curcumin colour (with annatto) in foods and especially fish is discussed.     

Oligomeric procyanidins inhibit cell migration and modulate the expression of migration and proliferation associated genes in human umbilical vascular endothelial cells

The consumption of flavan-3-ols has been associated with reduced risk of cardiovascular diseases and improvements in vascular function. However, the nature of the flavan-3-ols responsible and the mechanisms underlying the vascular responses are not fully understood. We used microarrays to search for molecular changes in response to the exposure to (-)-epicatechin (EC), procyanidin dimer B2, and a mixture of oligomeric procyanidins in human umbilical vein endothelial cells (HUVECs). No gene expression changes were detected in HUVECs exposed to EC or dimer B2, however, the oligomeric procyanidins induced significant gene expression changes in both resting and TNF-alpha-stimulated cells. In particular, the expression of genes such as ADAMTS1, THBS1, ANGPT2, CYR61, ET-1, EDG3, and PDE4B involved in endothelial cell migration and proliferation, were substantially over-represented. Also, exposure to the oligomers arrested the cells at the G(0)/G(1 )phase and inhibited cell migration. These data show that human endothelial cells respond to oligomeric procyanidins by exhibiting a less migratory phenotype and by a general modulation of the expression of genes that are associated with key events in the angiogenic process. The molecular changes associated with procyanidin treatment identified in this study are consistent with the beneficial effects of flavan-3-ols on vascular function.     

Dietary modulation of the expression of genes involved in short-chain fatty acid absorption in the rumen epithelium is related to short-chain fatty acid concentration and pH in the rumen of goats

We have tested the hypothesis that increased concentrate intake induces mRNA abundance alterations of genes involved in short-chain fatty acid (SCFA) absorption in the rumen epithelium of goats and these changes of mRNA abundance are probably related to ruminal SCFA concentration and ruminal pH. Goats (n = 12) were randomly allocated to 2 groups and fed either a low-concentrate (LC) diet (10% concentrate; n = 6) or a medium-concentrate (MC) diet (35% concentrate; n = 6) in 2 equal portions daily. Goats were fed separately with their respective diet for 3 wk. The goats were slaughtered 6 h after the morning feeding on d 22. In vivo, goats in the MC treatment exhibited a greater ruminal SCFA concentration (81.9 mM) compared with those in the LC treatment (58.0 mM), and the pH decreased from 7.03 to 6.63. Correspondingly, mRNA expression of candidates for SCFA⁻/HCO₃⁻ exchangers, namely downregulated in adenoma (DRA), putative anion transporter 1 (PAT1), and anion exchanger 2 (AE2) were increased in the MC group. Further, upregulation in monocarboxylate transporter 1 (MCT1) and monocarboxylate transporter 4 (MCT4) mRNA abundances was observed in the MC group. The expression of genes that help the rumen epithelial cells to maintain intracellular pH, including Na⁺/H⁺ exchanger 1 (NHE1), NHE2, NHE3, vacuolar H⁺ ATPase subunit B (vH⁺ATPase), and Na⁺/K⁺ ATPase pump subunit α1 (Na⁺/K⁺ATPase) were also enhanced in the MC group relative to the LC group. During in vitro studies with isolated rumen epithelial cells from goats, exposure to a pH of 6.8 increased MCT1 mRNA expression after 24 h of culture, whereas the mRNA expression of AE2 was downregulated. The presence of SCFA (20 mM) in the medium increased DRA, PAT1, AE2, MCT1, and Na⁺/K⁺ATPase mRNA expression. The expression of vH⁺ATPase was decreased by increased SCFA concentration. The mRNA expression of MCT4 did not vary in vitro with pH (6.8) or SCFA (20 mM). The expression of DRA was increased by synergistic effects of higher SCFA concentration and lower pH, similar to that of MCT1. Thus, diet-dependent rumen epithelial mRNA expression changes in genes involved in SCFA absorption are probably related to ruminal SCFA concentration and pH.     

Sesamin attenuates intercellular cell adhesion molecule‐1 expression in vitro in TNF‐α‐treated human aortic endothelial cells and in vivo in apolipoprotein‐E‐deficient mice

Sesame lignans have antioxidative and anti‐inflammatory properties. We focused on the effects of the lignans sesamin and sesamol on the expression of endothelial‐leukocyte adhesion molecules in tumor necrosis factor‐α (TNF‐α)‐treated human aortic endothelial cells (HAECs). When HAECs were pretreated with sesamin (10 or 100 μM), the TNF‐α‐induced expression of intercellular cell adhesion molecule‐1 (ICAM‐1) was significantly reduced (35 or 70% decrease, respectively) by Western blotting. Sesamol was less effective at inhibiting ICAM‐1 expression (30% decrease at 100 μM). Sesamin and sesamol reduced the marked TNF‐α‐induced increase in human antigen R (HuR) translocation and the interaction between HuR and the 3'UTR of ICAM‐1 mRNA. Both significantly reduced the binding of monocytes to TNF‐α‐stimulated HAECs. Sesamin significantly attenuated TNF‐α‐induced ICAM‐1 expression and cell adhesion by downregulation of extracellular signal‐regulated kinase 1/2 and p38. Furthermore, in vivo, sesamin attenuated intimal thickening and ICAM‐1 expression seen in aortas of apolipoprotein‐E‐deficient mice. Taken together, these data suggest that sesamin inhibits TNF‐α‐induced extracellular signal‐regulated kinase/p38 phosphorylation, nuclear translocation of NF‐κB p65, cytoplasmic translocalization of HuR and thereby suppresses ICAM‐1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that sesamin may prevent the development of atherosclerosis and inflammatory responses.     

The role of dietary oxidized cholesterol and oxidized fatty acids in the development of atherosclerosis

The etiology of atherosclerosis is complex and multifactorial but there is extensive evidence indicating that oxidized lipoproteins may play a key role. At present, the site and mechanism by which lipoproteins are oxidized are not resolved, and it is not clear if oxidized lipoproteins form locally in the artery wall and/or are sequestered in atherosclerotic lesions following the uptake of circulating oxidized lipoproteins. We have been focusing our studies on demonstrating that such potentially atherogenic oxidized lipoproteins in the circulation are at least partially derived from oxidized lipids in the diet. Thus, the purpose of our work has been to determine in humans whether oxidized dietary oxidized fats such as oxidized fatty acids and oxidized cholesterol are absorbed and contribute to the pool of oxidized lipids in circulating lipoproteins. When a meal containing oxidized linoleic acid was fed to normal subjects, oxidized fatty acids were found only in the postprandial chylomicron/chylomicron remnants (CM/RM) which were cleared from circulation within 8 h. No oxidized fatty acids were detected in low density lipoprotein (LDL) or high density lipoprotein (HDL) fractions at any time. However, when alpha-epoxy cholesterol was fed to human subjects, alpha-epoxy cholesterol in serum was found in CM/RM and also in endogenous very low density lipoprotein, LDL, and HDL and remained in the circulation for 72 h. In vitro incubation of the CM/RM fraction containing alpha-epoxy cholesterol with human LDL and HDL that did not contain alpha-epoxy cholesterol resulted in a rapid transfer of oxidized cholesterol from CM/RM to both LDL and HDL. We have suggested that cholesteryl ester transfer protein is mediating the transfer. Thus, alpha-epoxy cholesterol in the diet is incorporated into CM/RM fraction and then transferred to LDL and HDL contributing to lipoprotein oxidation. We hypothesize that diet-derived oxidized fatty acids in chylomicron remnants and oxidized cholesterol in remnants and LDL accelerate atherosclerosis by increasing oxidized lipid levels in circulating LDL and chylomicron remnants. This hypothesis is supported by our feeding experiments in animals. When rabbits were fed oxidized fatty acids or oxidized cholesterol, the fatty streak lesions in the aorta were increased by 100%. Moreover, dietary oxidized cholesterol significantly increased aortic lesions in apo-E and LDL receptor-deficient mice. A typical Western diet is rich in oxidized fats and therefore could contribute to the increased arterial atherosclerosis in our population.     

Berry juices, teas, antioxidants and the prevention of atherosclerosis in hamsters

The effects of raspberry, strawberry and bilberry juices and green and black tea on early atherosclerosis in hamsters were investigated. They received an atherogenic diet and at the same time either a juice or a tea at a daily dose corresponding to the consumption of 275 ml by a 70 kg human. After 12 weeks berry juices and teas inhibited aortic lipid deposition by 79–96% and triggered reduced activity of hepatic antioxidant enzymes, not accompanied by lowered plasma cholesterol. These findings suggest that moderate consumption of berry juices and teas can help prevent the development of early atherosclerosis. There were substantial differences between the five beverages in terms of composition and concentration of individual phenolic compounds that were present. This indicates that anti-atherosclerotic effects can be induced by a diversity of phenolic compounds rather than a few specific components. The possible mechanisms by which this is brought about are discussed.