Decreased aortic early atherosclerosis and associated risk factors in hypercholesterolemic hamsters fed a high- or mid-oleic acid oil compared to a high-linoleic acid oil

Fatty acids act on vascular endothelial cells and influence the development of cardiovascular disease

Endothelial cells (ECs) maintain the health of blood vessels and prevent the development of cardiovascular disease (CVD). Free saturated fatty acids (FAs) induce EC damage and increase the risk of CVD by promoting arteriosclerosis. Conversely, polyunsaturated FAs (PUFAs), such as docosahexaenoic acid, are thought to suppress EC damage induced during the early stages of CVD. This review describes the effects of multiple dietary FAs on EC disorders involved in the development of CVD. The roles of FAs in atherosclerosis and CVD were analyzed by evaluating articles published in PubMed, Science Direct, and Web of Science. Saturated FAs were found to induce EC damage by reducing the production and action of EC-derived nitric oxide. Oxidative stress, inflammation, and the renin-angiotensin system were found to be involved in EC disorder. Furthermore, n-3 PUFAs were found to reduce EC dysfunction and prevent the development of EC disorder. These results indicate that FAs may affect EC failure induced during the early stages of CVD and reduce the risk of developing the disease.

The Brassica napus fatty acid exporter FAX1-1 contributes to biological yield, seed oil content, and oil quality

BACKGROUND

In the oilseed crop Brassica napus (rapeseed), various metabolic processes influence seed oil content, oil quality, and biological yield. However, the role of plastid membrane proteins in these traits has not been explored.

RESULTS

Our genome-wide association study (GWAS) of 520 B. napus accessions identified the chloroplast membrane protein-localized FATTY ACID EXPORTER 1-1 (FAX1-1) as a candidate associated with biological yield. Seed transcript levels of BnaFAX1-1 were higher in a cultivar with high seed oil content relative to a low-oil cultivar. BnaFAX1-1 was localized to the plastid envelope. When expressed in Arabidopsis thaliana, BnaFAX1-1 enhanced biological yield (total plant dry matter), seed yield and seed oil content per plant. Likewise, in the field, B. napus BnaFAX1-1 overexpression lines (BnaFAX1-1-OE) displayed significantly enhanced biological yield, seed yield, and seed oil content compared with the wild type. BnaFAX1-1 overexpression also up-regulated gibberellic acid 4 (GA4) biosynthesis, which may contribute to biological yield improvement. Furthermore, oleic acid (C18:1) significantly increased in BnaFAX1-1 overexpression seeds.

CONCLUSION

Our results indicated that the putative fatty acid exporter BnaFAX1-1 may simultaneously improve seed oil content, oil quality and biological yield in B. napus, providing new approaches for future molecular breeding.

Plasma lipidomic profiling in murine mutants of Hermansky-Pudlak syndrome reveals differential changes in pro- and anti-atherosclerotic lipids

Atherosclerosis is characterized by the accumulation of lipid-rich plaques in the arterial wall. Its pathogenesis is very complicated and has not yet been fully elucidated. It is known that dyslipidemia is a major factor in atherosclerosis. Several different Hermansky-Pudlak syndrome (HPS) mutant mice have been shown either anti-atherosclerotic or atherogenic phenotypes, which may be mainly attributed to corresponding lipid perturbation. To explore the effects of different HPS proteins on lipid metabolism and plasma lipid composition, we analyzed the plasma lipid profiles of three HPS mutant mice, pa (Hps9 ^-/-), ru (Hps6 ^-/-), ep (Hps1 ^-/-), and wild-type (WT) mice. In pa and ru mice, some pro-atherosclerotic lipids, e.g. ceramide (Cer) and diacylglycerol (DAG), were down-regulated whereas triacylglycerol (TAG) containing docosahexaenoic acid (DHA) (22:6) fatty acyl was up-regulated when compared with WT mice. Several pro-atherosclerotic lipids including phosphatidic acid (PA), lysophosphatidylserine (LPS), sphingomyelin (SM), and cholesterol (Cho) were up-regulated in ep mice compared with WT mice. The lipid droplets in hepatocytes showed corresponding changes in these mutants. Our data suggest that the pa mutant resembles the ru mutant in its anti-atherosclerotic effects, but the ep mutant has an atherogenic effect. Our findings may provide clues to explain why different HPS mutant mice exhibit distinct anti-atherosclerotic or atherogenic effects after being exposed to high-cholesterol diets.

Overexpression of the olive acyl carrier protein gene (OeACP1) produces alterations in fatty acid composition of tobacco leaves

Taking into account that fatty acid (FA) biosynthesis plays a crucial role in lipid accumulation in olive (Olea europaea L.) mesocarp, we investigated the effect of olive acyl carrier protein (ACP) on FA composition by overexpressing an olive ACP cDNA in tobacco plants. The OeACP1.1A cDNA was inserted in the nucleus or in the chloroplast DNA of different tobacco plants, resulting in extensive transcription of the transgenes. The transplastomic plants accumulated lower olive ACP levels in comparison to nuclear-transformed plants. Moreover, the phenotype of the former plants was characterized by pale green/white cotyledons with abnormal chloroplasts, delayed germination and reduced growth. We suggest that the transplastomic phenotype was likely caused by inefficient olive ACP mRNA translation in chloroplast stroma. Conversely, total lipids from leaves of nuclear transformants expressing high olive ACP levels showed a significant increase in oleic acid (18:1) and linolenic acid (18:3), and a concomitant significant reduction of hexadecadienoic acid (16:2) and hexadecatrienoic acid (16:3). This implies that in leaves of tobacco transformants, as likely in the mesocarp of olive fruit, olive ACP not only plays a general role in FA synthesis, but seems to be specifically involved in chain length regulation forwarding the elongation to C18 FAs and the subsequent desaturation to 18:1 and 18:3.

Effects of combined oleic acid and fluoride at sub-MIC levels on EPS formation and viability of Streptococcus mutans UA159 biofilms

Despite the widespread use of fluoride, dental caries, a biofilm-related disease, remains an important health problem. This study investigated whether oleic acid, a monounsaturated fatty acid, can enhance the effect of fluoride on extracellular polysaccharide (EPS) formation by Streptococcus mutans UA159 biofilms at sub-minimum inhibitory concentration levels, via microbiological and biochemical methods, confocal fluorescence microscopy, and real-time PCR. The combination of oleic acid with fluoride inhibited EPS formation more strongly than did fluoride or oleic acid alone. The superior inhibition of EPS formation was due to the combination of the inhibitory effects of oleic acid and fluoride against glucosyltransferases (GTFs) and GTF-related gene (gtfB, gtfC, and gtfD) expression, respectively. In addition, the combination of oleic acid with fluoride altered the bacterial biovolume of the biofilms without bactericidal activity. These results suggest that oleic acid may be useful for enhancing fluoride inhibition of EPS formation by S. mutans biofilms, without killing the bacterium.

Chemopreventive effects of RXR-selective rexinoid bexarotene on intestinal neoplasia of Apc(Min/+) mice

Retinoid X receptor (RXR) has been implicated in several neoplastic diseases. Previously, we have shown that RXR-α is downregulated in human and rodent colonic tumors, suggesting a potential target for colon cancer prevention (http://www.cancer.org/Cancer/ColonandRectumCancer/DetailedGuide/colorectal-cancer-key-statistics). Experiments were designed to assess the chemopreventive efficacy of the selective RXR agonist bexarotene for the suppression of intestinal tumorigenesis in Apc(Min/+) mice. Before the efficacy studies, we determined that the maximal tolerated dose in C57BL/6J mice was less than 400 ppm. For the efficacy study, 6-week-old male and female C57BL/6J-Apc(Min/+) mice (nine mice per group) were fed diets containing 0, 30, and 60 ppm of bexarotene or 200 ppm of bexarotene for 80 days before intestinal tumors were evaluated. Dietary administration of 30 and 60 ppm of bexarotene suppressed the intestinal polyp formation by 38% (P < .015) and 60% (P < .0001) in males, respectively, and by 8.5% and 37% (P < .007) in females, respectively. Also, significant inhibition (50%-100%) of colonic tumor formation was observed in both male and female mice with bexarotene treatment. Administration of 200 ppm of bexarotene showed significant suppression of tumor formation (66%, P < .0001); however, it had significant toxicity. Intestinal tumors of bexarotene-fed mice showed significantly reduced expression of proliferating cell nuclear antigen (60%, P < .0001), cyclin D1, and cyclooxygenase 2 and increased RXR-α messenger RNA and uptake of oleate (34%, P < .01). Also, bexarotene-fed mice showed dose-dependent suppression of serum triglycerides (25%-72%, P < .0001) and inflammatory cytokines.

Oleic acid produced by a marine Vibrio spp. acts as an anti-Vibrio parahaemolyticus agent

It is known that some strains of Vibrio parahaemolyticus are responsible for gastroenteric diseases caused by the ingestion of marine organisms contaminated with these bacterial strains. Organic products that show inhibitory activity on the growth of the pathogenic V. parahaemolyticus were extracted from a Vibrio native in the north of Chile. The inhibitory organic products were isolated by reverse phase chromatography and permeation by Sephadex LH20, and were characterized by spectroscopic and spectrometric techniques. The results showed that the prevailing active product is oleic acid, which was compared with standards by gas chromatography and high-performance liquid chromatography (HPLC). These active products might be useful for controlling the proliferation of pathogenic clones of V. parahaemolyticus.

Use of hamster as a model to study diet-induced atherosclerosis

Golden-Syrian hamsters have been used as an animal model to assess diet-induced atherosclerosis since the early 1980s. Advantages appeared to include a low rate of endogenous cholesterol synthesis, receptor-mediated uptake of LDL cholesterol, cholesteryl ester transfer protein activity, hepatic apoB-100 and intestinal apoB-48 secretion, and uptake of the majority of LDL cholesterol via the LDL receptor pathway. Early work suggested hamsters fed high cholesterol and saturated fat diets responded similarly to humans in terms of lipoprotein metabolism and aortic lesion morphology. Recent work has not consistently replicated these findings. Reviewed was the literature related to controlled hamster feeding studies that assessed the effect of strain, background diet (non-purified, semi-purified) and dietary perturbation (cholesterol and/or fat) on plasma lipoprotein profiles and atherosclerotic lesion formation. F1B hamsters fed a non-purified cholesterol/fat-supplemented diet had more atherogenic lipoprotein profiles (nHDL-C > HDL-C) than other hamster strains or hamsters fed cholesterol/fat-supplemented semi-purified diets. However, fat type; saturated (SFA), monounsaturated or n-6 polyunsaturated (PUFA) had less of an effect on plasma lipoprotein concentrations. Cholesterol- and fish oil-supplemented semi-purified diets yielded highly variable results when compared to SFA or n-6 PUFA, which were antithetical to responses observed in humans. Dietary cholesterol and fat resulted in inconsistent effects on aortic lipid accumulation. No hamster strain was reported to consistently develop lesions regardless of background diet, dietary cholesterol or dietary fat type amount. In conclusion, at this time the Golden-Syrian hamster does not appear to be a useful model to determine the mechanism(s) of diet-induced development of atherosclerotic lesions.

Antimicrobial activity of n-6, n-7 and n-9 fatty acids and their esters for oral microorganisms

OBJECTIVE

This study is to assess the antibacterial activity of omega-6, -7, -9 (n-6, n-7, n-9) fatty acids against various oral microorganisms.

METHODS

The n-6, n-7, n-9 fatty acids, such as gamma-linoleic acid (GLA), linoleic acid (LA), arachidonic acid (ARA), palmitoleic acid (PA), and oleic acid (OA), their fatty acid ethyl esters, GLA-EE, LA-EE, ARA-EE, PA-EE, OA-EE, and their fatty acid methyl esters, GLA-ME, LA-ME, ARA-ME, PA-ME, OA-ME, were investigated for antimicrobial activity against oral pathogens Streptococcus mutans, Candida albicans, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis. Various concentrations of the fatty acids, their methyl and ethyl esters were tested against various oral pathogens in 96-well plates and blood-agar plate. The plates were incubated anaerobically or aerobically at 37 degrees C for 48h, and the colony forming units (CFU) were determined.

RESULTS

The data demonstrated that select n-6, n-7, n-9 fatty acids and their esters exhibited strong antimicrobial activity against these oral microorganisms, demonstrating some specificity for individual microbial species.

CONCLUSION

The potential use or the combinations of the n-6, n-7, n-9 fatty acids and/or their esters, provided in a local delivery vehicle to infected sites in the oral cavity, could be considered as an additional therapeutic approach to improving oral health.

Dietary olive oil prevents carbon tetrachloride-induced hepatic fibrosis in mice

AIM

The specific purpose of this study was to investigate the effects of dietary olive oil on hepatic fibrosis induced by chronic administration of carbon tetrachloride (CCl(4)) in the mouse. In addition, the effects of oleic acid, a major component of olive oil, on activation of hepatic stellate cells (HSCs) were investigated in vitro.

METHODS

Mice were fed liquid diets containing either corn oil (control, AIN-93) or olive oil (6.25 g/L) throughout experiments. Animals were treated with CCl(4) for 4 weeks intraperitoneally. The mRNA expression of TGF-beta1 and collagen 1alpha2 (col1alpha2) in the liver was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). The HSCs were isolated from mice, and co-cultured with either oleic acid (100 microM) or linoleic acid (100 microM) for 2 days. The expression of alpha-smooth muscle actin (alpha-SMA) was assessed by immunohistochemistry. In addition, the production of hydroxyproline was determined.

RESULTS

Serum alanine aminotransferase levels and the mRNA expression of TGF-beta and collalpha2 were significantly reduced by treatment of olive oil. Dietary olive oil blunted the expression of alpha-SMA in the liverand liver injury and hepatic fibrosis were prevented by treatment of olive oil. The number of alpha-SMA positive cells was significantly lower in HSCs co-cultured with oleic acid than in those co-cultured with linoleic acid. Concentration of hydroxyproline in culture medium was significantly lower in cells co-cultured with oleic acid than in the control.

CONCLUSIONS

Dietary olive oil prevents CCl(4)-induced tissue injury and fibrosis in the liver. Since oleic acid inhibited activation of HSCs, oleic acid may play a key role on this mechanism.

Effects of oleic acid and macrophage recruitment on cholesterol efflux in cell culture and in vivo

BACKGROUND AND AIM

Monounsaturated fatty acids in diets are beneficial for the plasma lipoprotein profile, but studies in cell culture point out that they may also be detrimental by inhibiting cholesterol efflux to apo AI.

METHODS AND RESULTS

In the present study we used mouse peritoneal macrophages, loaded with cholesterol and upregulated by cyclic AMP or by LXR/RXR ligands and compared the effect of oleic acid on cholesterol efflux to 3 different acceptors. Inhibition of cholesterol efflux by oleic acid ranged from 10 to 25% with HDL or 2.5% mouse serum, while efflux to phosphatidyl choline vesicles was not affected. Previously we reported that the LXR ligand, TO901317, retarded cholesterol removal in vivo from a modified LDL depot in muscle. This could have resulted from inhibition by unsaturated fatty acids or from reduction in macrophage recruitment due to the anti-inflammatory action of LXR.

CONCLUSIONS

Our current findings, of retardation of cholesterol clearance from the depot in the presence of low macrophage recruitment, support the latter possibility.

Effect of conjugated linoleic acid, vitamin E and their combination on lipid profiles and blood pressure of Iranian adults with active rheumatoid arthritis

The aim of this study was to assess the impact of conjugated linoleic acids (CLAs), vitamin E, and combination of these nutrients on serum lipid profiles and blood pressure (BP) in patients with active rheumatoid arthritis (RA). In a randomized, double-blind, placebo-controlled trial, 87 patients with active RA were divided into four groups receiving one of the following daily supplements for three months: Group C: CLAs 2.5 g equivalent to 2 g mixture of cis 9-trans 11 and trans 10-cis12 CLAs in a rate of 50/50; Group E: vitamin E: 400 mg; Group CE: CLAs and vitamin E at above doses: Group P: placebo. After supplementation, SBP levels decreased significantly in the group C in comparison with groups E and P and mean arterial pressure reduced significantly in groups C and CE. There weren't significant differences in the levels of prostaglandin E2 (PGE2), triglycerides, cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), LDL/HDL, cholesterol/HDL, fasting blood sugar, C-reactive protein (CRP), arylestrase activity, platelet count and body mass index between groups. CRP dropped nonsignificantly in groups P, C, E and CE (19%, 24%, 55%, and 39%, respectively). Erythrocytes sedimentation rate levels decreased in groups C, E and CE (P < or = 0.05, P < or = 0.05, P < or = 0.001, respectively). It is concluded that supplementation of CLAs decreased BP and vitamin E decreased CRP. Therefore co-supplementation of CLAs and vitamin E might be profitable for heart disease prevention in RA patients.

Bovine milk in human nutrition--a review

Milk and milk products are nutritious food items containing numerous essential nutrients, but in the western societies the consumption of milk has decreased partly due to claimed negative health effects. The content of oleic acid, conjugated linoleic acid, omega-3 fatty acids, short- and medium chain fatty acids, vitamins, minerals and bioactive compounds may promote positive health effects. Full-fat milk has been shown to increase the mean gastric emptying time compared to half-skimmed milk, thereby increasing the gastrointestinal transit time. Also the low pH in fermented milk may delay the gastric emptying. Hence, it may be suggested that ingesting full-fat milk or fermented milk might be favourable for glycaemic (and appetite?) regulation. For some persons milk proteins, fat and milk sugar may be of health concern. The interaction between carbohydrates (both natural milk sugar and added sugar) and protein in milk exposed to heat may give products, whose effects on health should be further studied, and the increasing use of sweetened milk products should be questioned. The concentration in milk of several nutrients can be manipulated through feeding regimes. There is no evidence that moderate intake of milk fat gives increased risk of diseases.

Olive oil preparation determines the atherosclerotic protection in apolipoprotein E knockout mice

Oils enriched in monounsaturated fatty acids do not seem to behave similarly in protecting against the development of atherosclerosis in animal models, which has been attributed to the presence of soluble phenolic compounds. To test the relevance of other components of oils in the prevention of atherosclerosis, two olive oils from the same cultivar devoid of soluble phenolic compounds were prepared using different procedures (pressure or centrifugation), characterized and fed to apolipoprotein E-deficient mice as 10% (w/w) of their diet. The 2 olive oils had similar levels of monounsaturated fatty acids and squalene, but they differed in their content of linoleic, phytosterols, tocopherols, triterpenes and waxes, which were particularly enriched in the test olive oil obtained by centrifugation. In mice that received a diet enriched in the olive oil derived through centrifugation, the progression of atherosclerosis was delayed compared to the mice that received standard olive oil. That effect was associated with decreases in plasma triglycerides, total and non-high-density lipoprotein cholesterol and isoprostane 8-iso-prostaglandin F(2alpha). Our results clearly indicate that the preparation of olive oil is crucial in determining its antiatherosclerotic effect, which extends beyond the presence of phenolic compounds. The test olive oil exerted its antiatherosclerotic effects by modifying plasma lipids and oxidative stress, and it might be a good candidate to replace other fats in functional foods.

Walnuts reduce aortic ET-1 mRNA levels in hamsters fed a high-fat, atherogenic diet

Walnut consumption is associated with reduced coronary vascular disease (CVD) risk; however, the mechanisms responsible remain incompletely understood. Recent clinical studies suggested that these mechanisms involve non-plasma lipid-related effects on endothelial function. Male Golden Syrian hamsters (12 groups, n=10-15) were fed for 26 wk atherosclerotic, high-fat, hyperlipidemic diets with increasing concentrations of whole walnuts (61-150 g/kg diet), or alpha-tocopherol (alpha-T, 8.1-81 mg/kg diet) and single diets with either walnut oil (32 g/kg diet) or pure gamma-tocopherol (gamma-T; 81 mg/kg diet) added. Aortic endothelin 1 (ET-1), an important endothelial regulator, was assayed as mRNA. Aortic cholesterol ester (CE) concentration along with other vascular stress markers (Cu/Zn and Mn superoxide dismutase, biliverdin reductase) and plasma lipid concentrations were determined. Hyperlipidemia (plasma LDL cholesterol approximately 6 times normal) occurred in all groups. Aortic CE concentration, a measure of atherosclerotic plaque, was highest in the lowest alpha-T only group and declined significantly with increasing alpha-T. The aortic CE of all walnut groups was decreased significantly relative to the lowest alpha-T only group but showed no dose response. The diets did not produce changes in the other vascular stress markers, whereas aortic ET-1 mRNA levels declined dramatically with increasing dietary walnuts (to a 75% reduction in the highest walnut content group compared with the lowest alpha-T group) but were unaltered in the alpha-T groups or gamma-T group. The study results are consistent with those of human walnut feeding studies and suggest that the mechanisms underlying those results are mediated in part by ET-1-dependent mechanisms. The contrasting results between the alpha-tocopherol or gamma-tocopherol diets and the walnut diets also make it unlikely that the non-plasma lipid-related CVD effects of walnuts are due to their alpha-tocopherol or gamma-tocopherol content. Finally, the results indicate that the walnut fat compartment is a likely location for the components responsible for the reduced aortic CE concentration.