Protective effects of EPA and deleterious effects of DHA on eNOS activity in Ea hy 926 cultured with lysophosphatidylcholine

Butyrate inhibits LPC-induced endothelial dysfunction by regulating nNOS-produced NO and ROS production

Lipids oxidation is a key risk factor for cardiovascular diseases. Lysophosphatidylcholine (LPC), the major component of oxidized LDL, is an important triggering agent for endothelial dysfunction and atherogenesis. Sodium butyrate, a short-chain fatty acid, has demonstrated atheroprotective properties. So, we evaluate the role of butyrate in LPC-induced endothelial dysfunction. Vascular response to phenylephrine (Phe) and acetylcholine (Ach) was performed in aortic rings from male mice (C57BL/6J). The aortic rings were incubated with LPC (10 μM) and butyrate (0.01 or 0.1 Mm), with or without TRIM (an nNOS inhibitor). Endothelial cells (EA.hy296) were incubated with LPC and butyrate to evaluate nitric oxide (NO) and reactive oxygen species (ROS) production, calcium influx, and the expression of total and phosphorylated nNOS and ERK½. We found that butyrate inhibited LPC-induced endothelial dysfunction by improving nNOS activity in aortic rings. In endothelial cells, butyrate reduced ROS production and increased nNOS-related NO release, by improving nNOS activation (phosphorylation at Ser1412). Additionally, butyrate prevented the increase in cytosolic calcium and inhibited ERk½ activation by LPC. In conclusion, butyrate inhibited LPC-induced vascular dysfunction by increasing nNOS-derived NO and reducing ROS production. Butyrate restored nNOS activation, which was associated with calcium handling normalization and reduction of ERK½ activation.

Omega-3 fatty acids decrease oxidative stress and inflammation in macrophages from patients with small abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is associated with inflammation and oxidative stress, the latter of which contributes to activation of macrophages, a prominent cell type in AAA. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to limit oxidative stress in animal models of AAA. The aim of this study was to evaluate the effect of the n-3 PUFA docosahexaenoic acid (DHA) on antioxidant defence in macrophages from patients with AAA. Cells were obtained from men with small AAA (diameter 3.0–4.5 cm, 75 ± 6 yr, n = 19) and age- matched male controls (72 ± 5 yr, n = 41) and incubated with DHA for 1 h before exposure to 0.1 µg/mL lipopolysaccharide (LPS) for 24 h. DHA supplementation decreased the concentration of tumour necrosis factor-α (TNF-α; control, 42.1 ± 13.6 to 5.1 ± 2.1 pg/ml, p < 0.01; AAA, 25.2 ± 9.8 to 1.9 ± 0.9 pg/ml, p < 0.01) and interleukin-6 (IL-6; control, 44.9 ± 7.7 to 5.9 ± 2.0 pg/ml, p < 0.001; AAA, 24.3 ± 5.2 to 0.5 ± 0.3 pg/ml, p < 0.001) in macrophage supernatants. DHA increased glutathione peroxidase activity (control, 3.2 ± 0.3 to 4.1 ± 0.2 nmol/min/ml/μg protein, p = 0.004; AAA, 2.3 ± 0.5 to 3.4 ± 0.5 nmol/min/ml/μg protein, p = 0.008) and heme oxygenase-1 mRNA expression (control, 1.5-fold increase, p < 0.001). The improvements in macrophage oxidative stress status serve as a stimulus for further investigation of DHA in patients with AAA.

Docosahexaenoic acid reduces adenosine triphosphate-induced calcium influx via inhibition of store-operated calcium channels and enhances baseline endothelial nitric oxide synthase phosphorylation in human endothelial cells

Docosahexaenoic acid (DHA), an omega-3-fatty acid, modulates multiple cellular functions. In this study, we addressed the effects of DHA on human umbilical vein endothelial cell calcium transient and endothelial nitric oxide synthase (eNOS) phosphorylation under control and adenosine triphosphate (ATP, 100 µM) stimulated conditions. Cells were treated for 48 h with DHA concentrations from 3 to 50 µM. Calcium transient was measured using the fluorescent dye Fura-2-AM and eNOS phosphorylation was addressed by western blot. DHA dose-dependently reduced the ATP stimulated Ca²⁺-transient. This effect was preserved in the presence of BAPTA (10 and 20 µM) which chelated the intracellular calcium, but eliminated after withdrawal of extracellular calcium, application of 2-aminoethoxy-diphenylborane (75 µM) to inhibit store-operated calcium channel or thapsigargin (2 µM) to delete calcium store. In addition, DHA (12 µM) increased ser1177/thr495 phosphorylation of eNOS under baseline conditions but had no significant effect on this ratio under conditions of ATP stimulation. In conclusion, DHA dose-dependently inhibited the ATP-induced calcium transient, probably via store-operated calcium channels. Furthermore, DHA changed eNOS phosphorylation suggesting activation of the enzyme. Hence, DHA may shift the regulation of eNOS away from a Ca²⁺ activated mode to a preferentially controlled phosphorylation mode.

Omega-3 fatty acids in prevention of diabetic retinopathy

OBJECTIVES

To review the competence of Omega-3 fatty acids in restricting the progression, thereby leading to prevention of diabetic retinopathy.

KEY FINDINGS

Owing to their anti-inflammatory and anti-angiogenic properties, Omega-3 fatty acids alleviate major aetiological agents. These fatty acids are renowned for their beneficial effects in various cardiovascular and other disorders; however, their potential to prevent the progression of diabetic retinopathy remains least explored.

SUMMARY

Utilizing this potential, we may develop effective prophylactic agents which markedly inhibit the advent of retinal angiogenesis and prevent the apoptosis of retinal endothelial and neuronal cells, thereby averting retinal degeneration, hence safeguarding diabetic patients from this sight-threatening complication.

Investigation of long chain omega-3 PUFAs on arterial blood pressure, vascular reactivity and survival in angiotensin II-infused Apolipoprotein E-knockout mice

Abdominal aortic aneurysm (AAA) is an inflammatory vascular disease. Long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs) decrease inflammation and oxidative stress in an angiotensin II-infused apolipoprotein E-knockout (ApoE(-/-)) mouse model of AAA. This study investigated the effects of LC n-3 PUFAs on blood pressure and vascular reactivity in fourteen angiotensin II-infused ApoE(-/-) male mice. Blood pressure was obtained using a non-invasive tail cuff method and whole blood was collected by cardiac puncture. Vascular reactivity of the thoracic aorta was assessed using wire myography and activation of endothelial nitric oxide synthase (eNOS) was determined by immunohistochemistry. A high LC n-3 PUFA diet increased the omega-3 index and reduced the n-6 to n-3 PUFA ratio. At day 10 post-infusion with angiotensin II, there was no difference in systolic blood pressure or diastolic blood pressure in mice fed the high or low n-3 PUFA diets. The high LC n-3 PUFA diet resulted in a non-significant trend for delay in time to death from abdominal aortic rupture. Vascular reactivity and eNOS activation remained unchanged in mice fed the high compared to the low LC n-3 PUFA diet. This study argues against direct improvement in vascular reactivity in ApoE(-/-) mice that were supplemented with n-3 PUFA for 8 weeks prior to infusion with angiotensin II.

Serum concentration of eicosapentaenoic acid is associated with cognitive function in patients with coronary artery disease

Background

Recent studies have shown that intake of n-3 polyunsaturated fatty acids (PUFAs) is associated with reduced risk of cognitive impairment and coronary artery disease (CAD); however, it is currently unknown whether reduced serum n-3 PUFA is associated with cognitive impairment in patients with CAD.

Methods

We retrospectively evaluated cognitive function with the mini-mental state examination (MMSE), serum levels of PUFAs (including eicosapentaenoic acid [EPA], docosahexaenoic acid [DHA], dihomogammalinolenic acid [DGLA], and arachidonic acid [AA]), cardiovascular risk factors (hypertension, dyslipidemia, diabetes mellitus, cerebrovascular disease, and history of current/previous smoking), and parameters of cardiac function (left ventricular ejection fraction and brain natriuretic peptide levels) in 146 Japanese CAD patients. The associations between the MMSE scores and the other parameters were evaluated.

Results

Pearson correlation analysis showed that EPA (R = 0.25, P <0.01), EPA/AA ratio (R = 0.22, P = 0.01), and left ventricular ejection fraction (R = 0.15, P = 0.04) were positively associated with MMSE score, and that age (R = −0.20, P <0.01) and brain natriuretic peptide levels (R = −0.28, P <0.01) were inversely associated with MMSE score. Multiple regression analysis showed that age (P <0.05) was negatively associated with MMSE score, while EPA (P <0.01) and EPA/AA ratio (P <0.05) were positively associated with MMSE score; however, sex; body mass index; left ventricular ejection fraction; levels of DHA, AA, and DGLA; DHA/AA ratio; brain natriuretic peptide; and presence of hypertension, dyslipidemia, diabetes mellitus, cerebrovascular disease, and history of current/previous smoking were statistically excluded.

Conclusions

Serum EPA concentration is associated with cognitive function in patients with CAD, suggesting that a low serum EPA level is a risk factor for cognitive impairment independent of cardiac function, including left ventricular ejection fraction. This correlation potentially lends further support to a role of dietary n-3 PUFAs in preventing the cognitive decline in CAD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2891-13-112) contains supplementary material, which is available to authorized users.

Oleoyl-lysophosphatidylcholine limits endothelial nitric oxide bioavailability by induction of reactive oxygen species

Previously we reported modulation of endothelial prostacyclin and interleukin-8 production, cyclooxygenase-2 expression and vasorelaxation by oleoyl- lysophosphatidylcholine (LPC 18:1). In the present study, we examined the impact of this LPC on nitric oxide (NO) bioavailability in vascular endothelial EA.hy926 cells. Basal NO formation in these cells was decreased by LPC 18:1. This was accompanied with a partial disruption of the active endothelial nitric oxide synthase (eNOS)- dimer, leading to eNOS uncoupling and increased formation of reactive oxygen species (ROS). The LPC 18:1-induced ROS formation was attenuated by the superoxide scavenger Tiron, as well as by the pharmacological inhibitors of eNOS, NADPH oxidases, flavin-containing enzymes and superoxide dismutase (SOD). Intracellular ROS-formation was most prominent in mitochondria, less pronounced in cytosol and undetectable in endoplasmic reticulum. Importantly, Tiron completely prevented the LPC 18:1-induced decrease in NO bioavailability in EA.hy926 cells. The importance of the discovered findings for more in vivo like situations was analyzed by organ bath experiments in mouse aortic rings. LPC 18:1 attenuated the acetylcholine-induced, endothelium dependent vasorelaxation and massively decreased NO bioavailability. We conclude that LPC 18:1 induces eNOS uncoupling and unspecific superoxide production. This results in NO scavenging by ROS, a limited endothelial NO bioavailability and impaired vascular function.

Omega-3 fatty acids modulate Weibel-Palade body degranulation and actin cytoskeleton rearrangement in PMA-stimulated human umbilical vein endothelial cells

Long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs) produce cardiovascular benefits by improving endothelial function. Endothelial cells store von Willebrand factor (vWF) in cytoplasmic Weibel-Palade bodies (WPBs). We examined whether LC n-3 PUFAs regulate WPB degranulation using cultured human umbilical vein endothelial cells (HUVECs). HUVECs were incubated with or without 75 or 120 µM docosahexaenoic acid or eicosapentaenoic acid for 5 days at 37 °C. WPB degranulation was stimulated using phorbol 12-myristate 13-acetate (PMA), and this was assessed by immunocytochemical staining for vWF. Actin reorganization was determined using phalloidin-TRITC staining. We found that PMA stimulated WPB degranulation, and that this was significantly reduced by prior incubation of cells with LC n-3 PUFAs. In these cells, WPBs had rounded rather than rod-shaped morphology and localized to the perinuclear region, suggesting interference with cytoskeletal remodeling that is necessary for complete WPB degranulation. In line with this, actin rearrangement was altered in cells containing perinuclear WPBs, where cells exhibited a thickened actin rim in the absence of prominent cytoplasmic stress fibers. These findings indicate that LC n-3 PUFAs provide some protection against WBP degranulation, and may contribute to an improved understanding of the anti-thrombotic effects previously attributed to LC n-3 PUFAs.

Antifibrotic effects of ω-3 fatty acids in the heart: one possible treatment for diastolic heart failure

Half of heart failure patients have diastolic heart failure, which has no effective treatments. Several studies indicate a role for ω-3 polyunsaturated fatty acids (PUFAs) in heart failure. Recent studies suggest that ω-3 PUFAs inhibit cardiac fibrosis and attenuate diastolic dysfunction. This opens up possible new avenues for treatment of diastolic heart failure. In this review, we focus on the antifibrotic effects of ω-3 PUFAs in heart and the underlying cellular and molecular mechanisms.

Omega-3 fatty acids and metabolic syndrome: effects and emerging mechanisms of action

Epidemiological, human, animal, and cell culture studies show that n-3 fatty acids, especially α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), reduce the risk factors of cardiovascular diseases. EPA and DHA, rather than ALA, have been the focus of research on the n-3 fatty acids, probably due to the relatively inefficient conversion of ALA to EPA and DHA in rodents and humans. This review will assess our current understanding of the effects and potential mechanisms of actions of individual n-3 fatty acids on multiple risk factors of metabolic syndrome. Evidence for pharmacological responses and the mechanism of action of each of the n-3 fatty acid trio will be discussed for the major risk factors of metabolic syndrome, especially adiposity, dyslipidemia, insulin resistance and diabetes, hypertension, oxidative stress, and inflammation. Metabolism of n-3 and n-6 fatty acids as well as the interactions of n-3 fatty acids with nutrients, gene expression, and disease states will be addressed to provide a rationale for the use of n-3 fatty acids to reduce the risk factors of metabolic syndrome.

Free fatty acids profile of the fetal brain and the plasma, liver, brain and kidneys of pregnant rats treated with sodium arsenite at mid-organogenesis

Free fatty acids (FFAs) are known to be markers of cellular membrane degradation through lipid peroxidation and are substrates for the production of reactive oxygen species (ROS). Oxidative stress, due to overproduction of ROS, may facilitate cellular insult by various toxicants. The ability of the rat conceptus to respond to toxic stress may be critical for normal development. In this study, the effects of the environmental toxicant sodium arsenite (NaAsO₂) on FFAs were investigated after administering a single oral dose, in water and in a lipid medium, to pregnant rats on gestational day (GD) 10, a time point at mid-organogenesis. NaAsO₂ was administered in deionized water (AsH₂O) or in half and half dairy cream (AsHH) at a dose of 41 mg sodium arsenite (NaAsO₂)/kg body weight. Control animals were treated with either dairy cream (HH) or deionized water (H₂O). The animals were sacrificed on GD 20. The fetal brain and the maternal liver, brain, plasma and kidneys were harvested. The FFAs were extracted and analyzed by gas chromatography. In the liver, there was an increase of myristic acid (1200%), myristoleic acid (174%), palmitic acid (47%), elaidic acid (456%), oleic acid (165%) and docosahexaenoic acid (224%) in the AsH₂O group as compared to the AsHH group. Oleic acid and arachidonic acid were increased by 192% and 900%, respectively, in the AsH₂O group as compared to the H₂O group, and myristic acid was decreased by 90% in the AsHH group as compared to the HH group. In the maternal brain, myristoleic acid was decreased by 91% in the AsH₂O group as compared to the H₂O group, and DHA increased by 148% in the AsHH group as compared to the HH group. In the fetal brain, myristic and stearic acids were decreased by 87% and 89%, respectively, in the AsH₂O group as compared to the AsHH group. Myristic, stearic and arachidonic acids were increased by 411%, 265%, and 144%, respectively, in the AsHH group as compared to the HH group. There was no effect on the fatty acids concentrations in the kidney or plasma as compared to controls. This study shows that NaAsO₂ produced a differential effect on the fatty acid profiles in rats. Further investigation is needed to elucidate the role of fatty acids in differential signaling and regulation by either the palmitoylation or myristoylation process of cellular functions in these target organs.

Fatty acids and signalling in endothelial cells

The endothelium is critical for the maintenance of a proper vessel function. Disturbances of endothelial function, called endothelial dysfunction, have serious implications, and lead to the development of atherosclerosis. It is well established that the risk for atherosclerosis development is influenced by nutritional factors such as the intake of certain fatty acids. Due to the fundamental role of the endothelium for atherosclerosis development, it is, therefore, likely that fatty acids directly influence the function of endothelial cells. The present review aims to explain the divergent effects of different types of fatty acids on cardiovascular disease risk by summarizing in vitro-data on the effects of fatty acids on (1) important signalling pathways involved in the modulation of endothelial cell function, and (2) endothelial cell functional properties, namely vasoactive mediator release and mononuclear cell recruitment, both of which are typically dysregulated during endothelial dysfunction.

Synergistic anti-inflammatory effects of low doses of curcumin in combination with polyunsaturated fatty acids: docosahexaenoic acid or eicosapentaenoic acid

Inflammatory response plays an important role not only in the normal physiology but also in the pathology such as cancers. As chronic inflammations are associated with malignancies, it is important to prevent inflammation-mediated neoplastic formation, promotion and/or progression. One possible intervention will be using cancer chemopreventive agents such as curcumin (CUR), a potent anti-inflammatory and anti-oxidative stress compound. Polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) are potent anti-inflammatory agents by decreasing the production of inflammatory eicosanoids, cytokines, and reactive oxygen species (ROS). The present study aims at examining whether CUR with DHA or EPA would have synergistic anti-inflammatory effects in RAW 264.7 cells. Non-toxic concentrations of single and combination of the compounds were investigated at 6, 12 and 24h. The nitric oxide (NO) suppression effects were most prominent at 24h. All the combinations of CUR and DHA or EPA with lower concentrations of CUR 5 microM and 25 microM of DHA or EPA were found to have synergistic effects in suppressing LPS-stimulated NO and endogenous NO levels. Importantly, very low doses of CUR 2.5 microM and DHA or EPA of 0.78 microM could synergistically suppress the LPS-induced prostaglandin E(2) (PGE(2)). The combinations were also found to suppress iNOS, COX-2, 5-lipoxygenase (5-LOX) and cPLA(2) but induce HO-1. Taken together, the present study clearly shows the synergistic anti-inflammatory as well as anti-oxidative stress effects of CUR and PUFA.