Docosahexaenoic acid potentiates interleukin-1beta induction of nitric oxide synthase through mechanism involving p44/42 MAPK activation in rat vascular smooth muscle cells

Enhancing Endothelial Function with Nutrient-Enriched Table Hen Eggs: A Randomized Study in Patients Recovering from Acute Coronary Syndrome

Purpose

This study investigated the effect of consumption of table eggs enriched with n-3 polyunsaturated fatty acids (n-3 PUFA), lutein, vitamin E and selenium on microvascular function, oxidative stress and inflammatory mediators in patients after acute coronary syndrome (ACS).

Patients and Methods

In a prospective, randomized, interventional, double-blind clinical trial, ACS patients were assigned to either the Nutri4 (N=15, mean age: 57.2 ± 9.2 years), or the Control group (N=13; mean age 56.8 ± 9.6 years). The Nutri4 group consumed three enriched hen eggs daily for three weeks, providing approximately 1.785 mg of vitamin E, 0.330 mg of lutein, 0.054 mg of selenium and 438 mg of n-3 PUFAs. Biochemical parameters, including serum lipids, liver enzymes, nutrient concentrations, serum antioxidant enzyme activity (catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD)), and markers of oxidative stress (thiobarbituric acid reactive substances (TBARS) and ferric reducing ability (FRAP)), were assessed before and after the dietary interventions. Additionally, arterial blood pressure, heart rate, body composition, fluid status, anthropometric measurements, and skin microvascular blood flow responses to various stimuli (postocclusive reactive hyperemia (PORH), acetylcholine- (Ach ID), and sodium nitroprusside- (SNP ID)) were measured using laser Doppler flowmetry (LDF) throughout the study.

Results

The intake of Nutri4 eggs led to a significant reduction in LDL cholesterol levels, while the levels of total cholesterol remained within the established reference values. Consuming Nutri4 eggs resulted in a 12.7% increase in serum vitamin E levels, an 8.6% increase in selenium levels, and demonstrated a favorable impact on microvascular reactivity, as evidenced by markedly improved PORH and ACh ID. Nutri4 eggs exerted a significant influence on the activity of GPx and SOD, with no observed changes in TBARS or FRAP values.

Conclusion

The consumption of Nutri4 eggs positively influenced microvascular function in individuals with ACS, without eliciting adverse effects on oxidative stress.

MCP1 Could Mediate FGF23 and Omega 6/Omega 3 Correlation Inversion in CKD

Fibroblast growth factor 23 (FGF23) concentrations rise after the early stages of chronic kidney disease (CKD). FGF23 is involved in inflammatory reactions closely associated with an incremented risk of cardiovascular disease (CVD). There is growing evidence that omega-6 (n-6) and n-3 polyunsaturated fatty acids (PUFA) can modulate inflammation through several mediators producing an opposite effect on cardiovascular (CV) risks. In this study, we explore whether there is any correlation between PUFA, FGF23, and inflammation in CKD patients. We evaluated, cross-sectionally, 56 patients at different stages of CKD. Monocyte chemoattractant protein 1 (MCP1), and intact and c-terminal FGF23 (iFGF23, cFGF23) were quantified by the ELISA, and the fatty acids (FA) profile was analyzed by gas chromatography. Concurrently with an eGFR decrease (p < 0.01) and an MCP1 increase (p = 0.031), we observed an inversion of the correlation between FGF23 and the n-6/n-3 ratio. This last correlation was inversed in CKD stage 3 (r2 (−) 0.502 p = 0.029) and direct in stage 5 (r2 0.657 p = 0.020). The increase in MCP1 seems to trigger events in the inversion of the correlation between FGF23 and the n-6/n-3 PUFA ratio. This result strongly encourages future studies on basal pathways, on possible pharmacological interventions, and on managing kidney transplant patients treated with immunosuppressive therapy.

Docosahexaenoic acid inhibits vascular smooth muscle cell migration and proliferation by decreasing microRNA‑155 expression levels

Vascular smooth muscle cell (VSMC) hyperplasia is a common cause of carotid restenosis. In the present study, the potential protective effects of docosahexaenoic acid (DHA) in carotid restenosis and the underlying mechanism of its effects were examined. VSMCs were treated with DHA, a polyunsaturated ω-3 fatty acid. Cell migration and proliferation were assessed using wound healing and Cell Counting Kit-8 assays and by measuring Ki-67 protein levels. Additionally, the expression levels of microRNA-155 were determined by reverse transcription-quantitative PCR (RT-qPCR). The involvement of microRNA-155 in the regulation of migration and proliferation was evaluated by transfecting VSMCs with microRNA mimics and inhibitors. Moreover, the reversal of migration and proliferation after transfection of VSMCs with the microRNA mimics and subsequent treatment with DHA was investigated. A target gene of microRNA-155 was identified using RT-qPCR and luciferase assays. The migration and proliferation of VSMCs, as well as the expression of microRNA-155 was inhibited by DHA stimulation. MicroRNA-155 regulated the migration and proliferation of VSMCs. Finally, proliferation and migration of VSMCs were reduced following DHA treatment, which was mediated by an increase in the expression levels of microRNA-155. Suppressor of cytokine signalling 1 (Socs1) was the target gene of microRNA-155. In conclusion, DHA inhibited VSMC migration and proliferation by reducing microRNA-155 expression. This effect may be caused by the microRNA-155 target gene Socs1.

Anti-Inflammatory Potential of n-3 Polyunsaturated Fatty Acids Enriched Hen Eggs Consumption in Improving Microvascular Endothelial Function of Healthy Individuals-Clinical Trial

The effects of consumption of n-3 polyunsaturated fatty acids (n-3 PUFAs) enriched hen eggs on endothelium-dependent and endothelium-independent vasodilation in microcirculation, and on endothelial activation and inflammation were determined in young healthy individuals. Control group (N = 21) ate three regular hen eggs/daily (249 mg n-3 PUFAs/day), and n-3 PUFAs group (N = 19) ate three n-3 PUFAs enriched hen eggs/daily (1053 g n-3 PUFAs/day) for 3 weeks. Skin microvascular blood flow in response to iontophoresis of acetylcholine (AChID; endothelium-dependent) and sodium nitroprusside (SNPID; endothelium-independent) was assessed by laser Doppler flowmetry. Blood pressure (BP), body composition, body fluid status, serum lipid and free fatty acids profile, and inflammatory and endothelial activation markers were measured before and after respective dietary protocol. Results: Serum n-3 PUFAs concentration significantly increased, AChID significantly improved, and SNPID remained unchanged in n-3 PUFAs group, while none was changed in Control group. Interferon-γ (pro-inflammatory) significantly decreased and interleukin-10 (anti-inflammatory) significantly increased in n-3 PUFAs. BP, fat free mass, and total body water significantly decreased, while fat mass, interleukin-17A (pro-inflammatory), interleukin-10 and vascular endothelial growth factor A significantly increased in the Control group. Other measured parameters remained unchanged in both groups. Favorable anti-inflammatory properties of n-3 PUFAs consumption potentially contribute to the improvement of microvascular endothelium-dependent vasodilation in healthy individuals.

Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review

Arachidonic acid (AA 20:4n-6) is an essential component of cell membranes and modulates cell membrane fluidity. AA is metabolized by cyclo-oxygenase (COX), lipoxygenase (LOX) and cytochrome P450 enzymes to form several metabolites that have important biological actions. Of all the actions, role of AA in the regulation of blood pressure and its ability to prevent both type 1 and type 2 diabetes mellitus seems to be interesting. Studies showed that AA and its metabolites especially, lipoxin A4 (LXA4) and epoxyeicosatrienoic acids (EETs), potent anti-inflammatory metabolites, have a crucial role in the pathobiology of hypertension and diabetes mellitus. AA, LXA4 and EETs regulate smooth muscle function and proliferation, voltage gated ion channels, cell membrane fluidity, membrane receptors, G-coupled receptors, PPARs, free radical generation, nitric oxide formation, inflammation, and immune responses that, in turn, participate in the regulation blood pressure and pathogenesis of diabetes mellitus. In this review, role of AA and its metabolites LXA4 and EETs in the pathobiology of hypertension, pre-eclampsia and diabetes mellitus are discussed. Based on several lines of evidences, it is proposed that a combination of aspirin and AA could be of benefit in the prevention and management of hypertension, pre-eclampsia and diabetes mellitus.

Characterisation of the vasodilation effects of DHA and EPA, n-3 PUFAs (fish oils), in rat aorta and mesenteric resistance arteries

Background and purpose

Increasing evidence suggests that the omega-3 polyunsaturated acids (n-3 PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are beneficial to cardiovascular health, promoting relaxation of vascular smooth muscle cells and vasodilation. Numerous studies have attempted to study these responses, but to date there has not been a systematic characterisation of both DHA and EPA mediated vasodilation in conduit and resistance arteries. Therefore, we aimed to fully characterise the n-3 PUFA-induced vasodilation pathways in rat aorta and mesenteric artery.

Methods

Wire myography was used to measure the vasomotor responses of freshly dissected rat mesenteric artery and aorta. Arteries were pre-constricted with U46619 and cumulative concentrations of either DHA or EPA (10 nM-30 μM) were added. The mechanisms by which n-3 PUFA relaxed arteries were investigated using inhibitors of vasodilator pathways, which include: nitric oxide synthase (NOS; L-NAME), cycloxygenase (COX; indomethacin), cytochrome P450 epoxygenase (CYP450; clotrimazole); and calcium-activated potassium channels (K_Ca), SK_Ca (apamin), IK_Ca (TRAM-34) and BK_Ca (paxilline).

Results

Both DHA- and EPA-induced relaxations were partially inhibited following endothelium removal in rat mesenteric arteries. Similarly, in aorta EPA-induced relaxation was partially suppressed due to endothelium removal. CYP450 also contributed to EPA-induced relaxation in mesenteric artery. Inhibition of IK_Ca partially attenuated DHA-induced relaxation in aorta and mesenteric artery along with EPA-induced relaxation in mesenteric artery. Furthermore, this inhibition of DHA- and EPA-induced relaxation was increased following the additional blockade of BK_Ca in these arteries.

Conclusions

This study provides evidence of heterogeneity in the vasodilation mechanisms of DHA and EPA in different vascular beds. Our data also demonstrates that endothelium removal has little effect on relaxations produced by either PUFA. We demonstrate IK_Ca and BK_Ca are involved in DHA-induced relaxation in rat aorta and mesenteric artery; and EPA-induced relaxation in rat mesenteric artery only. CYP450 derived metabolites of EPA may also be involved in BK_Ca dependent relaxation. To our knowledge this is the first study indicating the involvement of IK_Ca in n-3 PUFA mediated relaxation.

The protective role of YAP1 on ER stress-induced cell death in vascular smooth muscle cells

Apoptosis of vascular smooth muscle cells (VSMCs) has been implicated in the progression of atherosclerosis, especially in vascular remodelling and plaque rupture. Although it is known that Yes-associated protein 1 (YAP1) is a critical molecule that regulates cell proliferation, differentiation and apoptosis, the role of YAP1 in VSMCs apoptosis remains unknown. In this study, we investigated whether YAP1 modulates VSMC apoptosis induced by endoplasmic reticulum (ER) stress. In cultured VSMC, tunicamycin caused cell death accompanied by an increase in caspase-3 processing and C/EBP homologous protein (CHOP) expression. YAP1 protein expression was downregulated by tunicamycin and the phosphorylation of YAP1 at the Ser127 site was significantly increased by tunicamycin. Tunicamycin further decreased cell viability followed by an increase in caspase-3 processing in the absence of YAP1 when compared with treatment only with tunicamycin or siYAP1. On the other hand, overexpression of a constitutively active YAP1 (YAP1-5SA), which lacks five serine phosphorylation sites, significantly prevented the caspase-3 processing and restored the decrease in cell viability induced by tunicamycin. Overexpression of YAP1-5SA significantly inhibited tunicamycin-induced caspase-8 processing without affecting phosphorylation of p-38 and Akt. Furthermore, the overexpression of YAP1-5SA significantly restored the decrease in ANKRD1 expression induced by tunicamycin. The inhibition of tunicamycin-induced caspase-3 cleavage by YAP1-5SA was markedly attenuated in ANKRD1-knockdown cells. These results demonstrate that ER stress can alter intracellular YAP1 protein expression in VSMCs and that YAP1 is protective against VSMC apoptosis induced by ER stress through inhibiting caspase8/3 activation mediated in part by upregulation of ANKRD1.

Omega-3 polyunsaturated fatty acids improve endothelial function in humans at risk for atherosclerosis: A review

Epidemiology studies and clinical trials show that omega-3 polyunsaturated fatty acids (n-3 PUFAs) can prevent atherosclerotic morbidity and evidence suggests this may be mediated by improving endothelial dysfunction. Endothelial dysfunction is characterized by reduced vasodilation and a pro-inflammatory, pro-thrombotic state, and is an early pathological event in the development of atherosclerosis. Flow-mediated dilation (FMD), a gold standard for assessing endothelial dysfunction, is a predictor of future cardiovascular events and coronary heart disease risk. Notably, risk factors for endothelial dysfunction include classic risk factors for atherosclerosis: Elevated lipids, diabetes, hypertension, elevated BMI, cigarette smoking, and metabolic syndrome. In this paper, we review the ability of n-3 PUFAs to improve endothelial dysfunction in individuals with classic risk factors for atherosclerosis, but lacking diagnosed atherosclerotic disease, with the goal of identifying those individuals that might gain the most vasoprotection from n-3 PUFA supplements. We include trials using eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or alpha-linolenic acid (ALA) alone, or EPA+DHA; and assessing endothelial function by FMD, forearm blood flow, or peripheral arterial tonometry. We found that n-3 PUFAs improved endothelial dysfunction in 16 of 17 studies in individuals with hyperlipidemia, elevated BMI, metabolic syndrome, or that smoked cigarettes, but only in 2 of 5 studies in diabetics. Further, these trials showed that use of EPA+DHA consistently improve endothelial dysfunction; ALA-enriched diets appear promising; but use of EPA or DHA alone requires further study. We conclude that individuals with hyperlipidemia, elevated BMI, metabolic syndrome, or that smoke could derive vaosprotective benefits from EPA+DHA supplementation.

Analysis of Vascular Cell Response to Hypertension Induced by Pressure Loading and Its Application as a Tool for Exploring Pharmacological Modes of Action

Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression is induced by interleukin-1β (IL-1β) stimulation in vascular smooth muscle cells (VSMCs), resulting in the production of nitric oxide and prostaglandins such as PGI₂. The expression of iNOS and COX-2 in cultured VSMCs isolated from 6-7-week-old stroke-prone spontaneously hypertensive rats (SHRSP) is significantly lower than in cells of normotensive Wistar Kyoto rats (WKY). These reductions are also found in cells exposed to pulsatile atmospheric pressure between 80-160 mmHg at a rate of 4 cycles/min, which simulates systolic hypertension. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, potentiates IL-1β-induced iNOS and COX-2 expression in VSMCs isolated from WKY, but not those from SHRSP. In response to endothelial injury at a local site, iNOS and COX-2 induction in VSMCs may function primarily as a defensive and compensatory mechanism for endothelial dysfunction by preventing the development of pathological conditions. Thus, in certain pathological conditions associated with hypertension, vascular walls with reduced iNOS and COX-2 expression may aggravate or initiate further vascular injury. In this situation, DHA may contribute to maintaining homeostasis in VSMCs by potentiating iNOS and COX-2 expression. Using cells isolated from a genetic pathological animal model alongside cells exposed to experimental pathological conditions can be an effective tool for the analysis of cell response to hypertension and exploring pharmacological modes of action in vitro.

Phytanic acid attenuates insulin-like growth factor-1 activity via nitric oxide-mediated γ-secretase activation in rat aortic smooth muscle cells: possible implications for pathogenesis of infantile Refsum disease

BACKGROUND

Infantile Refsum disease (IRD), a peroxisomal disease with defective phytanic acid oxidation, causes neurological impairment and development delay. Insulin-like growth factor-1 (IGF-1) regulates child development and to understand molecular mechanism(s) of IRD, we examined the effect of phytanic acid (PA) on IGF-1 activity.

METHODS

Bromodeoxyuridine (BrdU) incorporation was measured in rat aortic smooth muscle cell (SMC) cultures following treatment with fetal bovine serum (FBS), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) or IGF-1 in the absence or presence of PA. Gene expression and protein contents of IGF-1 receptor (IGF-1R) and PDGF receptor (PDGFR) were examined using quantitative PCR and western blotting.

RESULTS

PA inhibited mitogenic activities of FBS, PDGF and IGF-1 with more pronounced effect on IGF-1-induced bromodeoxyuridine (BrdU) incorporation. Palmitic acid or lignoceric acids did not inhibit IGF-1 activity. PA had no effect on PDGFR mRNA/protein levels but markedly increased IGF-1R mRNA levels. PA and nitric oxide (NO) markedly decreased IGF-1R protein. L-NAME, a NO synthase inhibitor and DAPT, a γ-secretase inhibitor, alleviated PA-induced decrease in IGF-1R protein. Both PA and NO donor increased γ-secretase activity which was alleviated by L-NAME.

CONCLUSION

This study demonstrates that PA attenuates IGF-1 activity possibly through IGF-1R impairment and NO-mediated modulation of γ-secretase activity.

Phytanic acid activates NADPH oxidase through transactivation of epidermal growth factor receptor in vascular smooth muscle cells

BACKGROUND

Phytanic acid (PA) has been implicated in development of cancer and its defective metabolism is known to cause life-threatening conditions, such as Refsum disease, in children. To explore molecular mechanisms of phytanic acid-induced cellular pathology, we investigated its effect on NADPH oxidase (NOX) and epidermal growth factor receptor (EGFR) in rat aortic smooth muscle cells (RASMC).

METHODS

Smooth muscle cells were isolated from rat aortae using enzymic digestion with collagenase and elastase. Cultured RASMC were treated with varying concentrations (0.5-10 μg/ml) of phytanic acid in the presence/absence of fetal bovine serum (FBS) and/or EGFR inhibitor, AG1478. Following treatment with experimental agents, NOX activity was assayed in RASMC cultures by luminescence method. Gene expression of NOX-1 and p47phox was assessed using RT-PCR. NOX-1, p47phox and, total EGFR protein and its phosphorylated form were measured by Western blotting.

RESULTS

Treatment of RASMC with supraphysiological concentrations (>2.5 μg/ml) of PA significantly (p < 0.01) increased the NOX activity. PA also significantly increased gene/protein expression of NOX-1 and p47phox whereas p22phox and p67phox remained unaffected. Interestingly, PA (2.5-10 μg/ml) markedly (2-3 folds) increased the total and phosphorylated EGFR. Treatment of cells with EGFR inhibitor, AG1478, significantly blocked the PA-induced enhancement of NOX activity.

CONCLUSIONS

Our findings that PA transactivates EGFR and induces NOX activity in vascular smooth muscle cells provide new insights into molecular mechanisms of PA's role in cancer and Refsum disease.

Recombinant interleukin-1β dilates steelhead trout coronary microvessels: effect of temperature and role of the endothelium, nitric oxide and prostaglandins

Interleukin (IL)-1β is associated with hypotension and cardiovascular collapse in mammals during heat stroke, and the mRNA expression of this pro-inflammatory cytokine increases dramatically in the blood of Atlantic cod (Gadus morhua) at high temperatures. These data suggest that release of IL-1β at high temperatures negatively impacts fish cardiovascular function and could be a primary determinant of upper thermal tolerance in this taxa. Thus, we measured the concentration-dependent response of isolated steelhead trout (Oncorhynchus mykiss) coronary microvessels (<150 μm in diameter) to recombinant (r) IL-1β at two temperatures (10 and 20°C). Recombinant IL-1β induced a concentration-dependent vasodilation with vessel diameter increasing by approximately 8 and 30% at 10(-8) and 10(-7) mol l(-1), respectively. However, this effect was not temperature dependent. Both vessel denudation and cyclooxygenase blockade (by indomethacin), but not the nitric oxide (NO) antagonist L-NIO, inhibited the vasodilator effect of rIL-1β. In contrast, the concentration-dependent dilation caused by the endothelium-dependent calcium ionophore A23187 was completely abolished by L-NIO and indomethacin, suggesting that both NO and prostaglandin signaling mechanisms exist in the trout coronary microvasculature. These data: (1) are the first to demonstrate a functional link between the immune and cardiovascular systems in fishes; (2) suggest that IL-1β release at high temperatures may reduce systemic vascular resistance, and thus, the capacity of fish to maintain blood pressure; and (3) provide evidence that both NO and prostaglandins play a role in regulating coronary vascular tone, and thus, blood flow.

Polyunsaturated fatty acids and their effects on cardiovascular disease

Dietary polyunsaturated fatty acids (PUFAs) affect a wide variety of physiological processes. Much attention has been given to the n-3 PUFAs and their role in the prevention and treatment of cardiovascular disease, stemming from evidence obtained through a number of epidemiological studies and clinical trials. Investigators are now focused on elucidating the pathways and mechanisms for the biological action of n-3 PUFAs. Dietary intervention is recognized as a key measure in patient therapy and in the maintenance of human health in general. This review provides a summary of several important clinical trials, and while the exact modes of action of n-3 PUFA are not known, current viewpoints regarding the mechanisms of these fatty acids on atherosclerosis, circulating lipid profile, cell membranes, cell proliferation, platelet aggregation and cardiac arrhythmias are discussed.

Docosahexaenoic acid suppresses neuroinflammatory responses and induces heme oxygenase-1 expression in BV-2 microglia: implications of antidepressant effects for ω-3 fatty acids

Accumulating evidence suggests that the pathophysiology of depression might be associated with neuroinflammation, which could be attenuated by pharmacological treatment for depression. Omega-3 polyunsaturated fatty acids (PUFAs) are anti-inflammatory and exert antidepressant effects. The aim of this study was to identify the molecular mechanisms through which docosahexaenoic acid (DHA), the main omega-3 PUFA in the brain, modulates oxidative reactions and inflammatory cytokine production in microglial and neuronal cells. The results of this study showed that DHA reduced expressions of tumor necrosis factor-α, interleukin-6, nitric oxide synthase, and cyclo-oxygenase-2, induced by interferon-γ, and induced upregulation of heme oxygenase-1 (HO-1) in BV-2 microglia. The inhibitory effect of DHA on nitric oxide production was abolished by HO-1 inhibitor zinc protoporphyrin IX. In addition, DHA caused AKT and ERK activation in a time-dependent manner, and the DHA-induced HO-1 upregulation could be attenuated by PI-3 kinase/AKT and MEK/ERK inhibitors. DHA also increased IKKα/β phosphorylation, IκBα phosphorylation, and IκBα degradation, whereas both nuclear factor-κB and IκB protease inhibitors could inhibit DHA-induced HO-1 expressions. The other major n-3 PUFA, eicosapentaenoic acid, showed similar effects of DHA on inflammation and HO-1 in repeated key experiments. In connecting with inflammation hypothesis of depression and clinical studies supporting the antidepressant effects of omega-3 PUFAs, this study provides a novel implication of the antidepressant mechanisms of DHA.

Endogenous n-3 fatty acids protect ovariectomy induced bone loss by attenuating osteoclastogenesis

Beneficial effects of n-3 fatty acids (FA) on bone mineral density (BMD) have been reported in mice, rats and human beings, but the precise mechanisms involved have not been described. This study used the Fat-1 mouse, a transgenic model that synthesizes n-3 FA from n-6 FA to directly determine if outcome of bone health were correlated with n-3 FA. Ovariectomized (Ovx) and sham operated wild-type (WT) and Fat-1 mice were fed an AIN-93M diet containing 10% corn oil for 24 weeks. BMD was analysed by dual energy x-ray absorptiometry. Fat-1 Ovx mice exhibited significantly lower level of osteotropic factors like receptor activator of NF-kappaB ligand and tartrate-resistant acid phosphatase (TRAP)5b in serum and higher BMD in distal femoral metaphysis, proximal tibial metaphysis, femoral diaphysis and lumbar vertebra as compared to WT Ovx mice. LPS-stimulated bone marrow (BM) cells from Fat-1 Ovx mice produced significantly lower level of pro-inflammatory cytokines like tumour necrosis factor-alpha, interleukin (IL)-1-beta, IL-6 and higher level of anti-inflammatory cytokines like IL-10, IFN-gamma and higher level of nitric oxide as compared to BM cells from WT Ovx mice. LPS-stimulated COX-II activity as well as NF-kappaB activation in BM cells from Fat-1 Ovx mice was significantly less as compared to BM cells from WT Ovx mice. Furthermore, Fat-1 BM cells generated significantly less number of TRAP osteoclast-like cells as compared to WT BM cells. In conclusion, we offer further insight into the mechanisms involved in preventing the BMD loss in Ovx mice by n-3 FA using a Fat-1 transgenic mouse model.

Endogenous n-3 fatty acids protect ovariectomy induced bone loss by attenuating osteoclastogenesis

Beneficial effects of n-3 fatty acids (FA) on bone mineral density (BMD) have been reported in mice, rats and human beings, but the precise mechanisms involved have not been described. This study used the Fat-1 mouse, a transgenic model that synthesizes n-3 FA from n-6 FA to directly determine if outcome of bone health were correlated with n-3 FA. Ovariectomized (Ovx) and sham operated wild-type (WT) and Fat-1 mice were fed an AIN-93M diet containing 10% corn oil for 24 weeks. BMD was analysed by dual energy x-ray absorptiometry. Fat-1 Ovx mice exhibited significantly lower level of osteotropic factors like receptor activator of NF-kappaB ligand and tartrate-resistant acid phosphatase (TRAP)5b in serum and higher BMD in distal femoral metaphysis, proximal tibial metaphysis, femoral diaphysis and lumbar vertebra as compared to WT Ovx mice. LPS-stimulated bone marrow (BM) cells from Fat-1 Ovx mice produced significantly lower level of pro-inflammatory cytokines like tumour necrosis factor-alpha, interleukin (IL)-1-beta, IL-6 and higher level of anti-inflammatory cytokines like IL-10, IFN-gamma and higher level of nitric oxide as compared to BM cells from WT Ovx mice. LPS-stimulated COX-II activity as well as NF-kappaB activation in BM cells from Fat-1 Ovx mice was significantly less as compared to BM cells from WT Ovx mice. Furthermore, Fat-1 BM cells generated significantly less number of TRAP osteoclast-like cells as compared to WT BM cells. In conclusion, we offer further insight into the mechanisms involved in preventing the BMD loss in Ovx mice by n-3 FA using a Fat-1 transgenic mouse model.

Effects of dietary decosahexaenoic acid (DHA) on eNOS in human coronary artery endothelial cells

Endothelial dysfunction occurs in heart disease and may reduce functional capacity via attenuations in peripheral blood flow. Dietary decosahexaenoic acid (DHA) may improve this dysfunction, but the mechanism is unknown. This study determined if DHA enhances expression and activity of eNOS in cultured human coronary artery endothelial cells (HCAEC). HCAEC from 4 donors were treated with 5 nM, 50 nM, or 1 microM DHA for 7 days to model chronic DHA exposure. A trend for increased expression of endothelial nitric oxide synthase (eNOS) and phospho-eNOS was observed with 5 and 50 nM DHA. DHA also enhanced expression of 2 proteins instrumental in activation of eNOS: phospho-Akt (5 and 50 nM) and HSP90 (50 nM and 1 microM). Vascular endothelial growth factor-induced activation of Akt increased NOx in treated (50 nM DHA) versus untreated HCAEC (9.2 +/- 1.0 vs 3.3 +/- 1.1 micromol/microg protein/microL). Findings suggest that DHA enhances eNOS and Akt activity, augments HSP90 expression, and increases NO bioavailability in response to Akt kinase activation.

Nutrients: the environmental regulation of cardiovascular gene expression

The complexity of nutrient-gene interactions has led to the development of a new branch in the nutrition sciences, the nutrigenomics. The individual susceptibility to nutrients based on environment --> genotype --> phenotype interplay makes this new research field extremely promising although complex. In this review, we highlight and examine recent findings and the most relevant hypotheses on the role of the diet in the onset and progression of cardiovascular diseases. The effect of unbalanced diets on the cardiovascular system is considered one of the most important risk factors both for ischemic and degenerative myocardial pathologies. The concept that nutrigenomics could help in improving public and personal health is becoming tangible indicating future directions for basic and applied research in the pathophysiology of cardiovascular disease.

Sphingosine 1-phosphate induces cyclooxygenase-2 via Ca2+-dependent, but MAPK-independent mechanism in rat vascular smooth muscle cells

The effects of sphingosine 1-phosphate (S1P) on prostaglandin I(2) (PGI(2)) production and cyclooxygenase (COX) expression in cultured rat vascular smooth muscle cells (VSMCs) were investigated. S1P stimulated PGI(2) production in a concentration-dependent manner, which was completely suppressed by NS-398, a selective COX-2 inhibitor, as determined by radioimmunoassay. S1P stimulated COX-2 protein and mRNA expressions in a concentration- and time-dependent manner, while it had no effect on COX-1 expression. S1P(2) and S1P(3) receptors mRNA were abundantly expressed in rat VSMCs. Suramin, an antagonist of S1P(3) receptor, almost completely inhibited S1P-induced COX-2 expression. Pretreatment of VSMCs with pertussis toxin (PTX) partially, but significantly inhibited S1P-induced PGI(2) production and COX-2 expression. S1P also activated extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). However, neither PD 98059, a selective inhibitor of ERK activation, nor SB 203580, a selective inhibitor of p38 MAPK, had a significant inhibitory effect on S1P-induced COX-2 expression, suggesting that the MAPK activation does not play main roles in S1P-induced COX-2 induction. S1P-induced COX-2 expression was inhibited by PP2, an inhibitor of Src-family tyrosine kinase, Ca(2+) depletion, and GF 109203X, an inhibitor of protein kinase C (PKC). These results suggest that S1P stimulates COX-2 induction in rat VSMCs through mechanisms involving Ca(2+)-dependent PKC and Src-family tyrosine kinase activation via S1P(3) receptor coupled to PTX-sensitive and -insensitive G proteins.

The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina

In this work we advance the hypothesis that omega-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) exhibit cytoprotective and cytotherapeutic actions contributing to a number of anti-angiogenic and neuroprotective mechanisms within the retina. omega-3 LCPUFAs may modulate metabolic processes and attenuate effects of environmental exposures that activate molecules implicated in pathogenesis of vasoproliferative and neurodegenerative retinal diseases. These processes and exposures include ischemia, chronic light exposure, oxidative stress, inflammation, cellular signaling mechanisms, and aging. A number of bioactive molecules within the retina affect, and are effected by such conditions. These molecules operate within complex systems and include compounds classified as eicosanoids, angiogenic factors, matrix metalloproteinases, reactive oxygen species, cyclic nucleotides, neurotransmitters and neuromodulators, pro-inflammatory and immunoregulatory cytokines, and inflammatory phospholipids. We discuss the relationship of LCPUFAs with these bioactivators and bioactive compounds in the context of three blinding retinal diseases of public health significance that exhibit both vascular and neural pathology. How is omega-3 LCPUFA status related to retinal structure and function? Docosahexaenoic acid (DHA), a major dietary omega-3 LCPUFA, is also a major structural lipid of retinal photoreceptor outer segment membranes. Biophysical and biochemical properties of DHA may affect photoreceptor membrane function by altering permeability, fluidity, thickness, and lipid phase properties. Tissue DHA status affects retinal cell signaling mechanisms involved in phototransduction. DHA may operate in signaling cascades to enhance activation of membrane-bound retinal proteins and may also be involved in rhodopsin regeneration. Tissue DHA insufficiency is associated with alterations in retinal function. Visual processing deficits have been ameliorated with DHA supplementation in some cases. What evidence exists to suggest that LCPUFAs modulate factors and processes implicated in diseases of the vascular and neural retina? Tissue status of LCPUFAs is modifiable by and dependent upon dietary intake. Certain LCPUFAs are selectively accreted and efficiently conserved within the neural retina. On the most basic level, omega-3 LCPUFAs influence retinal cell gene expression, cellular differentiation, and cellular survival. DHA activates a number of nuclear hormone receptors that operate as transcription factors for molecules that modulate reduction-oxidation-sensitive and proinflammatory genes; these include the peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and the retinoid X receptor. In the case of PPAR-alpha, this action is thought to prevent endothelial cell dysfunction and vascular remodeling through inhibition of: vascular smooth muscle cell proliferation, inducible nitric oxide synthase production, interleukin-1 induced cyclooxygenase (COX)-2 production, and thrombin-induced endothelin 1 production. Research on model systems demonstrates that omega-3 LCPUFAs also have the capacity to affect production and activation of angiogenic growth factors, arachidonic acid (AA)-based vasoregulatory eicosanoids, and MMPs. Eicosapentaenoic acid (EPA), a substrate for DHA, is the parent fatty acid for a family of eicosanoids that have the potential to affect AA-derived eicosanoids implicated in abnormal retinal neovascularization, vascular permeability, and inflammation. EPA depresses vascular endothelial growth factor (VEGF)-specific tyrosine kinase receptor activation and expression. VEGF plays an essential role in induction of: endothelial cell migration and proliferation, microvascular permeability, endothelial cell release of metalloproteinases and interstitial collagenases, and endothelial cell tube formation. The mechanism of VEGF receptor down-regulation is believed to occur at the tyrosine kinase nuclear factor-kappa B (NFkappaB). NFkappaB is a nuclear transcription factor that up-regulates COX-2 expression, intracellular adhesion molecule, thrombin, and nitric oxide synthase. All four factors are associated with vascular instability. COX-2 drives conversion of AA to a number angiogenic and proinflammatory eicosanoids. Our general conclusion is that there is consistent evidence to suggest that omega-3 LCPUFAs may act in a protective role against ischemia-, light-, oxygen-, inflammatory-, and age-associated pathology of the vascular and neural retina.

Docosahexaenoic Acid Enhances Cyclooxygenase-2 Induction by Facilitating p44/42, but Not p38, Mitogen-Activated Protein Kinase Activation in Rat Vascular Smooth Muscle Cells

The effect of docosahexaenoic acid (DHA) on cyclooxygenase expression induced by interleukin (IL)-1beta and phorbol 12-myristate 13-acetate (PMA) in rat vascular smooth muscle cells (VSMCs) was investigated in order to clarify the cellular mechanism of cardiovascular protective effects. DHA and eicosapentaenoic acid slightly enhanced IL-1beta-induced cyclooxygenase (COX)-2, but not COX-1, expression, whereas arachidonic acid had no effect. DHA also slightly enhanced PMA-induced COX-2 expression. DHA stimulated both rapid and prolonged activation of p44/42, but not p38, mitogen-activated protein kinase (MAPK) induced by IL-1beta and PMA. These results suggest that DHA enhances the COX-2 expression by selectively facilitating p44/42 MAPK activation in VSMCs.

The relationship between membrane pathology and language disorder in schizophrenia

Receptive language disorder in schizophrenia has been hypothesized to involve a fundamental deficit in the temporal (time-based) dynamics of brain function that includes disruptions to patterns of activation and synchronization. In this paper, candidate mechanisms and pathways that could account for this basic deficit are discussed. Parallels are identified between the patterns of language dysfunction observed for schizophrenia and dyslexia, two separate clinical disorders that may share a common abnormality in cell membrane phospholipids. A heuristic is proposed which details a trajectory involving an interaction of brain fatty acids and second-messenger function that modulates synaptic efficacy, and, in turn, influences language processing in schizophrenia patients. It is additionally hypothesized that a primary deficit of functional excitation originating in the cerebellum, in combination with a compensatory decrease of functional inhibition in the prefrontal cortex, influences receptive language dysfunction in schizophrenia.

Cardiovascular protective effects of n-3 polyunsaturated fatty acids with special emphasis on docosahexaenoic acid

It is widely accepted that n-3 polyunsaturated fatty acids (PUFAs) rich in fish oils protect against several types of cardiovascular diseases such as myocardial infarction, arrhythmia, atherosclerosis, or hypertension. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may be the active biological components of these effects. Although the precise cellular and molecular mechanisms underlying the beneficial effects are still uncertain, the protective effects of n-3 PUFAs are attributable to their direct effects on vascular smooth muscle cell (VSMC) functions. These n-3 PUFAs activate K(+)(ATP) channels and inhibit certain types of Ca(2+) channels, probably via at least 2 distinct mechanisms. N-3 PUFAs favorably alter the eicosanoid profile and regulate cytokine-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 via mechanisms involving modulation of signaling transduction events. N-3 PUFAs also modulate VSMC proliferation, migration, and apoptosis. These recent data suggest that modulation of these VSMC functions contribute to the beneficial effects of n-3 PUFAs on various cardiovascular disorders. Furthermore, recent studies strongly suggest that DHA has more potent and beneficial effects than EPA. However, many questions about the cellular and molecular mechanisms still remain to be answered.

The potential role for arachidonic and docosahexaenoic acids in protection against some central nervous system injuries in preterm infants

The risk of central nervous, visual, and auditory damage increases from 2/1000 live births in the normal birthweight to > 200/1000 as birthweight falls below 1500 g. Such babies are most likely to be born preterm. Advances in infant care have led to increasing numbers of very-low-birthweight, preterm infants surviving to school age with moderate to severe brain damage. Steroids are one of the current treatments, but they cause significant, long-term problems. The evidence reported here suggests an additional approach to protecting the very preterm infant by supporting neurovascular membrane integrity. The complications of preterm, very-low-birthweight babies include bronchopulmonary dysplasia, retinopathy of prematurity, intraventricular hemorrhage, periventricular leukomalacia, and necrotizing enterocolitis, all of which have a vascular component. Arachidonic acid (AA) and DHA are essential, structural, and functional constituents of cell membranes. They are especially required for the growth and function of the brain and vascular systems, which are the primary biofocus of human fetal growth. Molecular dynamics and experimental evidence suggest that DHA could be the ligand for the retinoid X receptor (RXR) in neural tissue. RXR activation is an obligatory step in signaling to the nucleus and in the regulation of gene expression. Very preterm babies are born with minimal fat stores and suboptimal circulating levels of these nutrients. Postnatally, they lose the biomagnification of the proportions of AA and DHA by the placenta for the fetus. No current nutritional management repairs these deficits. The placental biomagnification profile highlights AA rather than DHA. The resultant fetal FA profile closely resembles that of the vascular endothelium and not the brain. Without this nourishment, cell membrane abnormalities would be predicted. We present a scientific rationale for a common pathogenic process in the complications of prematurity.