Effect of linoleic acid on endothelial cell inflammatory mediators

Impact of chronic fluoxetine exposure on zebrafish: From fatty acid profile to behavior

The consumption of antidepressants, such as fluoxetine, has increased over the years and, as a result, they are increasingly found in aquatic systems. Given the increasing use of zebrafish as an animal model in toxicological studies, this work proposed to evaluate the effects of chronic exposure, for 21 days, to fluoxetine at environmentally relevant concentrations (1, 10, 100, and 1000 ng/L). The behavioral tests performed did not reveal significant effects of fluoxetine. However, oxidative stress and changes in energy metabolism were detected after exposure to the highest concentrations of fluoxetine tested, namely a decrease in glutathione S-transferase (GST) activity (decrease of ca. 31%), increase in catalase (CAT) activity (increase of ca. 71%), and decrease in lactate dehydrogenase (LDH) activity (decrease of ca. 53%). Analysis of the fatty acid profile (FA) revealed a decrease in the omega-3 FA, docosahexaenoic acid (DHA), C22:6 (decrease in relative abundance between 6% and 8% for both the head and body), an increase in omega-6 FA, linoleic acid (LA), C18:2, (increased relative abundance between 8% and 11% in the head and between 5% and 9% in the body), which may suggest changes in the inflammatory state of these organisms. The integrated analysis adopted proved to be useful in detecting subindividual effects of fluoxetine and modes of action in fish.

Improvements in markers of inflammation and coagulation potential following a 5-day high-fat diet rich in cottonseed oil vs. Olive oil in healthy males

Low-grade inflammation is believed to be a risk factor for chronic diseases and is nutritionally responsive. Cottonseed oil (CSO), which is rich in n-6 polyunsaturated fats, has been shown to lower cholesterol and other chronic disease risk factors. The purpose of this secondary analysis was to determine the comparative responses of markers of inflammation and coagulation potential of healthy adult males consuming diets rich in CSO vs. olive oil (OO).

METHODS

Fifteen normal-weight males, ages 21.7 ± 2.58y, completed a randomized crossover trial. Each intervention consisted of a 3-day lead-in diet and a 5-day outpatient, controlled feeding intervention (CSO or OO). There was a 2 to 4-week washout period between interventions. The 5-day intervention diets were 35 % carbohydrate, 15 % protein, and 50 % fat, enriched with either CSO or OO (44 % of total energy from oil). At pre- and post- diet intervention visits, a fasting blood draw was collected for analysis of markers of inflammation (Tumor Necrosis Factor Alpha (TNF-α), Interleukin-6 (IL-6), C-Reactive Protein (CRP)) and coagulation potential (Tissue Factor (TF), Plasminogen Activator Inhibitor-1 (PAI-1)).

RESULTS

The CSO-enriched diets reduced TNF-α (CSO: -0.12 ± 0.02 pg/ml, OO: -0.01 ± 0.05 pg/ml; p < 0.01) and TF (CSO: -0.59 ± 0.68 pg/ml, OO: 1.13 ± 0.83 pg/ml; p = 0.02) compared to OO diets. There were no differences in IL-6, CRP, or PAI-1 between diets.

CONCLUSION

A 5-day, CSO-enriched diet may be sufficient to reduce inflammation and coagulation potential compared to OO-enriched diets in a healthy male population which could have implications in chronic disease prevention.

Important roles of linoleic acid and α-linolenic acid in regulating cognitive impairment and neuropsychiatric issues in metabolic-related dementia

Metabolic syndrome (MetS), which is characterized by insulin resistance, high blood glucose, obesity, and dyslipidemia, is known to increase the risk of dementia accompanied by memory loss and depression. The direct pathways and specific mechanisms in the central nervous system (CNS) for addressing fatty acid imbalances in MetS have not yet been fully elucidated. Among polyunsaturated acids, linoleic acid (LA, n6-PUFA) and α-linolenic acid (ALA, n3-PUFA), which are two essential fatty acids that should be provided by food sources (e.g., vegetable oils and seeds), have been reported to regulate various cellular mechanisms including apoptosis, inflammatory responses, mitochondrial biogenesis, and insulin signaling. Furthermore, inadequate intake of LA and ALA is reported to be involved in neuropathology and neuropsychiatric diseases as well as imbalanced metabolic conditions. Herein, we review the roles of LA and ALA on metabolic-related dementia focusing on insulin resistance, dyslipidemia, synaptic plasticity, cognitive function, and neuropsychiatric issues. This review suggests that LA and ALA are important fatty acids for concurrent treatment of both MetS and neurological problems.

Linoleic acid-induced ANGPTL4 inhibits C2C12 skeletal muscle differentiation by suppressing Wnt/β-catenin

Skeletal muscle differentiation is an essential process in embryonic development as well as regeneration and repair throughout the lifespan. It is well-known that dietary fat intake impacts biological and physiological function in skeletal muscle, however, understanding of the contribution of nutritional factors in skeletal muscle differentiation is limited. Therefore, the objective of the current study was to evaluate the effects of free fatty acids (FFAs) on skeletal muscle differentiation in vitro. We used C2C12 murine myoblasts and treated them with various FFAs, which revealed a unique response of angiopoietin-like protein-4 (ANGPTL4) with linoleic acid (LA) treatment that was associated with reduced differentiation. LA significantly inhibited myotube formation and lowered the protein expression of myogenic regulatory factors, including MyoD and MyoG and increased Pax7 during cell differentiation. Next, recombinant ANGPTL4 protein or siRNA knockdown of ANGPTL4 was employed to examine its role in skeletal muscle differentiation, and we confirmed that ANGPTL4 knockdown at day 2 and -6 of differentiation restored myotube formation in the presence of LA. RNA-sequencing analysis revealed that ANGPTL4-mediated inhibition of skeletal muscle differentiation at day 2 as well as LA at day 2 or -6 led to a reduction in Wnt/β-catenin signaling pathways. We confirmed that LA reduced Wnt11 and Axin2 while increasing expression of the Wnt inhibitor, Dkk2. ANGPTL4 knockdown increased β-catenin protein in the nucleus in response to LA and increased Axin2 and Wnt11 expression. Taken together, these results demonstrate that LA induced ANGPTL4 inhibits C2C12 differentiation by suppressing Wnt/β-catenin signaling.

The Relationship Between Linoleic Acid Intake and Psychological Disorders in Adults

Background

The association between linoleic acid (LA) intake and mental disorders has not been extensively studied in Middle-Eastern populations. We investigated the association between LA intake and the prevalence of depression, anxiety, and psychological distress in a large group of Iranian adults.

Methods

This cross-sectional study was conducted on 3,362 middle-aged adults. LA intake was determined through a validated dish-based 106-item semiquantitative food frequency questionnaire (FFQ). The validated Hospital Anxiety and Depression Scale (HADS) and General Health Questionnaire (GHQ) were used to define psychological disorders.

Results

The prevalence of depression, anxiety, and psychological distress among the study population was 28.6, 13.6, and 22.6%, respectively. After adjustment for potential confounders, individuals in the top quartile of LA intake had 41% more likely to be depressed compared to those in the bottom quartile (OR = 1.41, 95% CI: 1.02–1.95). Stratified analysis by sex revealed that men in the fourth quartile of LA intake, compared to the first quartile, had 80% higher odds of depression, after considering all potential confounders (OR = 1.80, 95% CI: 1.01–3.19). More consumption of LA was also associated with higher odds of depression in older adults (OR = 2.45, 95% CI: 1.46–4.10) and normal-weight individuals (OR = 1.75, 95% CI: 1.13–2.72). Additionally, higher intake of LA was related to 90% higher odds of psychological distress in older participants (OR = 1.90, 95% CI: 1.08–3.36). No significant relation was found between LA intake and anxiety.

Conclusion

We found that higher intake of LA, as percentage of energy, was positively associated with depression, especially in men, older adults, and normal-weight subjects. Higher intake of LA was also related to higher odds of psychological distress in older individuals. More studies, particularly prospective cohorts, are needed to confirm these findings.

Associations Between Preconception Plasma Fatty Acids and Pregnancy Outcomes

BACKGROUND

Although fatty acids are involved in critical reproductive processes, the relationship between specific fatty acids and fertility is uncertain. We investigated the relationship between preconception plasma fatty acids and pregnancy outcomes.

METHODS

We included 1,228 women attempting pregnancy with one to two previous pregnancy losses from the EAGeR trial (2007-2011). Plasma fatty acids were measured at baseline. We used log-binomial regression to assess associations between fatty acids and pregnancy, pregnancy loss, and live birth, adjusting for age, race, smoking, BMI, physical activity, income, parity, treatment arm, and cholesterol.

RESULTS

Although total saturated fatty acids (SFAs) were not associated with pregnancy outcomes, 14:0 (myristic acid; relative risk [RR] = 1.10, 95% confidence interval [CI] = 1.02, 1.19, per 0.1% increase) and 20:0 (arachidic acid; RR = 1.05, 95% CI = 1.01, 1.08, per 0.1% increase) were positively associated with live birth. Findings suggested a positive association between total monounsaturated fatty acids (MUFAs) and pregnancy and live birth and an inverse association with loss. Total polyunsaturated fatty acids (PUFAs) were associated with lower probability of pregnancy (RR = 0.97, 95% CI = 0.95, 1.00) and live birth (RR = 0.96, 95% CI = 0.94, 0.99), and increased risk of loss (RR = 1.10, 95% CI = 1.00, 1.20), per 1% increase. Trans fatty acids and n-3 fatty acids were not associated with pregnancy outcomes.

CONCLUSIONS

Preconception total plasma MUFAs were positively associated with pregnancy and live birth. PUFAs were inversely associated with pregnancy outcomes. Specific SFAs were associated with a higher probability of live birth. Our results suggest that fatty acids may influence pregnancy outcomes.

Inhibitory effect of modified silkworm pupae oil in PDGF-BB-induced proliferation and migration of vascular smooth muscle cells

Silkworm pupae oil (SPO) has been reported to have various biological activities in improving blood circulation. However, the protective action of SPO against vascular disorders remains unknown. A new formulation of SPO was prepared through an esterification and saponification process. The composition of unsaturated fatty acids in silkworm pupae oil sodium salt (SPOS) was then analyzed by LC/MS to show α-linolenic acid (11.0%), linoleic acid (73.2%), palmitic acid (3.1%), oleic acid (12.0%), and stearic acid (0.7%). The in vitro studies were performed to find out the efficacy of SPOS on platelet-derived growth factor (PDGF-BB) induced vascular smooth muscle cell (VSMC) migration and proliferation. PDGF-BB (10 ng/mL) induced abnormal migration and proliferation of VSMCs, whereas exposure to SPOS (30 μg/mL) significantly reduced the PDGF-BB-induced cell migration and proliferation. The extracellular signal-regulated kinase1/2 (ERK1/2) and phosphorylation of ERK1/2 were determined by immunoblot analysis and the ERK1/2 phosphorylation in PDGF-BB-stimulated VSMCs was downregulated by SPOS (30 μg/mL) treatment. These results indicate that SPOS may be a helpful and useful agent as a functional food and drug against vascular disorders.

Interesterified palm olein lowers postprandial glucose-dependent insulinotropic polypeptide response in type 2 diabetes

PURPOSE

We aim to investigate the postprandial effects of palm olein (PO) and chemically interesterified palm olein (IPO) with different proportions of palmitic acid at the sn-2 position using high oleic sunflower oil (HOS) as control fat on concentrations of gut hormones, glucose homeostasis, satiety, lipid and inflammatory parameters in type 2 diabetic (T2D) subjects.

METHODS

Using a randomised double-blind crossover design, 21 (men = 6, women = 15) T2D subjects consumed test meals (3.65 MJ) consisting of a high fat muffin (containing 50 g test fats provided as PO, IPO or HOS) and a milkshake. Postprandial changes in gut hormones, glucose homeostasis, satiety, lipid and inflammatory parameters after meals were analysed. Some of the solid fractions of the IPO were removed and thus the fatty acid composition of the PO and IPO was not entirely equal (PO vs IPO: palmitate 39.8 vs 38.7; oleate 43.6 vs 45.1). PO, IPO and HOS contained 9.7, 38.9 and 0.2 g/100 g total fatty acids of palmitic acid at the sn-2 position, respectively. At 37 °C, IPO contained 4.2% SFC whereas PO and HOS were completely melted.

RESULTS

Our novel observation shows that the incremental area under curve (iAUC) 0-6 h of plasma GIP concentration was on average 16% lower following IPO meal compared with PO and HOS (P < 0.05) meals. Serum C-peptide concentrations exhibited a significant meal × gender interaction (P = 0.009). No differences between test meals were noted for other measurements.

CONCLUSIONS

This study shows no adverse effect of interesterification on hormones associated with glucose homeostasis notably GLP-1 in T2D subjects.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01906359. https://clinicaltrials.gov/ct2/show/NCT01906359.

Preconception Plasma Phospholipid Fatty Acids and Fecundability

CONTEXT

Fatty acids (FAs) are important for reproductive processes, including steroidogenesis, though associations with fecundability, as measured by time to pregnancy (TTP), are unclear.

OBJECTIVE

To investigate the relationship between preconception plasma phospholipid FA (PPFA) levels and time to human chorionic gonadotropin-pregnancy among women with prior pregnancy loss.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort of 1228 women attempting pregnancy (aged 18 to 40 years, with one or two prior pregnancy losses) followed for up to six cycles at four US university medical centers during 2006 to 2012. PPFA levels were measured at baseline.

MAIN OUTCOME MEASURES

Associations with fecundability overall and by body mass index (BMI) group after adjusting for confounders were estimated using fecundability odds ratios (FORs) and 95% CIs. False discovery rate (FDR) was used to account for multiple comparisons.

RESULTS

Monounsaturated fatty acids (MUFAs) were associated with increased fecundability or shorter TTP [FOR, 1.08 (95% CI, 1.01 to 1.16) per unit increase in percentage of total FAs], whereas polyunsaturated fatty acids (PUFAs) were associated with decreased fecundability or longer TTP [FOR, 0.95 (95% CI, 0.91 to 1.00) per 1% change], though associations only remained significant after FDR adjustment among women with BMI <25 kg/m2. Saturated FA and trans FA were not associated with fecundability. Omega-3 FAs and omega-6 linoleic acid were not associated with fecundability.

CONCLUSION

We observed associations between preconception MUFA and PUFA levels and fecundability among women with normal BMI, highlighting the importance of FA composition among normal-weight women with prior pregnancy loss.

Novel Phospholipid Signature of Depressive Symptoms in Patients With Coronary Artery Disease

Background

Depression in patients with coronary artery disease (CAD) is associated with increased cardiovascular morbidity. Given the proinflammatory actions of phospholipids, aberrant phospholipid metabolism may be an etiological mechanism linking CAD and depression. Our primary objective was to identify a phospholipid biomarker panel that characterizes CAD patients with significant depressive symptoms from those without.

Methods and Results

We performed a targeted lipidomic analysis on CAD patients with significant depressive symptoms (n=37, Center for Epidemiologic Studies Depression score ≥16) and those without (n=49). Phospholipid species were selected using partial least‐square discriminant analysis, and the ability of the resulting model to discriminate between groups was evaluated using receiver operator characteristic curves. Biosignature scores were calculated from this model, and analyses of covariance were performed to compare intergroup differences in biosignature scores, with adjustment for clinical differences between patients. Those with significant depressive symptoms had lower cardiopulmonary fitness, more prevalent history of depression, and a greater number of vascular risk factors. A model of 10 phospholipid species had an area under the curve value of 0.84 (95% confidence interval 0.72‐0.95), sensitivity of 0.73, and specificity of 0.71. This model passed permutation testing (n=1000, P<0.001). Biosignature scores were higher in those with significant depressive symptoms after adjustment for potential confounders (F[1.86]=14.39, P<0.0005).

Conclusions

The present findings support the role of proinflammatory phospholipid species in the presence of depression in CAD patients from the CAROTID trial (Coronary Artery Disease Randomized Omega‐3 Trial in Depression). Future investigations should aim to replicate findings in larger data sets and clarify possible pathophysiological mechanisms.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00981383.

Anti‑inflammatory effects on murine macrophages of ethanol extracts of Lygodium japonicum spores via inhibition of NF‑κB and p38

The spores of Lygodium japonicum (Thunb.) Sw. (L. japonicum) have been used in traditional Chinese medicine for the treatment of various inflammatory diseases. However, the molecular mechanisms underlying their anti‑inflammatory effects have yet to be elucidated. In the present study, we investigated the anti‑inflammatory effects of ethanol extracts of L. japonicum spores (ELJ) by measuring the production of inflammatory mediators, and explored the molecular mechanisms underlying the effects of ELJ in murine macrophages in vitro using immunoblotting analyses. At non‑cytotoxic concentrations of (50‑300 µg/ml), ELJ was revealed to significantly suppress the production of nitric oxide (NO) and tumor necrosis factor (TNF)‑α in lipopolysaccharide (LPS)‑stimulated murine RAW 264.7 macrophages; ELJ repressed the production of interleukin (IL)‑6 only at high concentrations (≥200 µg/ml). The ELJ‑mediated decrease in NO production was demonstrated to depend on the downregulation of inducible NO synthase mRNA and protein expression. Conversely, the mRNA and protein expression of cyclooxygenase‑2 were not affected by ELJ. In addition, ELJ was revealed to inhibit the mRNA expression of IL‑6, IL‑1β, and TNF‑α in LPS‑stimulated RAW 264.7 macrophages. The effects of ELJ on proinflammatory mediators may have been due to the stabilization of inhibitor of κBα and the inhibition of p38 mitogen‑activated protein kinase (MAPK). These results suggested that ELJ may suppress LPS‑induced inflammatory responses in murine macrophages in vitro, through the negative regulation of p38 MAPK and nuclear factor (NF)‑κB. Therefore, ELJ may have potential as a novel candidate for the development of therapeutic strategies aimed at alleviating inflammation.

Effects of the duration of hyperlipidemia on cerebral lipids, vessels and neurons in rats

Background

The present study was designed to investigate the effects of hyperlipidemia on the cerebral lipids, vessels and neurons of rats, and to provide experimental evidence for subsequent intervention.

Method

One hundred adult SD rats, half of which were male and half of which were female, were randomly divided into five groups on the basis of serum total cholesterol (TC) levels. Four groups were fed a hypercholesterolemic diet (rat chow supplemented with 4% cholesterol, 1% cholic acid and 0.5% thiouracil – this is also called a CCT diet) for periods of 1 week, 2 weeks, 3 weeks and 4 weeks, respectively. A control group was included. The levels of serum lipids, cerebral lipids, free fatty acids (FFA), interleukin-6 (IL-6), interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF), oxidized low density lipoprotein (ox-LDL), A-beta precursor proteins (APP), amyloid beta (Aβ), glial fibrillary acidic protein (GFAP) and tight junction protein Claudin-5 were measured after the experiment. The pathologic changes and apoptosis of the rat brains were evaluated.

Results

Compared with the control group, after 1 week of a CCT diet, the levels of serum total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and brain triglycerides had increased by 2.40, 1.29 and 1.75 and 0.3 times, respectively. The serum high density lipoprotein cholesterol (HDL-C) had decreased by 0.74 times (P < 0.05) and the expression of IL-1, TNF-α and GFAP in the brains had increased (P < 0.05). In the second week, the expression of FFA and APP in the brains, and the amount of apoptotic neurons, had increased (P < 0.05). In the third week, the levels of VEGF, Ox-LDL and Aβ had increased, and the expression of Claudin-5 had decreased in the brains (P < 0.05). In the fourth week, the levels of TC, LDL-C and the amount of apoptotic neurons had increased (P < 0.05). The correlation analysis showed a positive correlation among FFA, TNF-α, VEGF, ox-LDL, Aβ, GFAP and neuronal apoptosis in the rat brains, and they all were negatively correlated with Claudin-5 (P < 0.05).

Conclusion

Hyperlipidemia may activate astrocytes by means of high levels of TG that will have direct toxic effects on the cerebral vessels and neurons by causing the secretion of TNF-α and IL-1 in the brains of rats. In the metabolic procession, brain tissue was shown to generate FFA that aggravated the biosynthesis of ox-LDL. With the extension of the duration of hyperlipidemia, high levels of cerebral TC and LDL-C were shown to aggravate the deposition of Aβ, induce the secretion of VEGF, reduce the expression of tight junction protein Claudin-5 and change the permeability of blood–brain barriers to factors that could damage cerebral vessels and neurons.

Maternal Weight Gain Regulates Omega-3 Fatty Acids in Male, Not Female, Neonates

The fetus largely depends on maternal supply and placental transport for its source of long-chain polyunsaturated fatty acids (LCPUFAs), which are essential for proper neurological and cardiovascular development. Pregnancy complications such as diabetes reduces neonatal LCPUFA supply, but little is known of how fatty acid delivery is affected by maternal body type or weight gain in uncomplicated pregnancies. In a cross-sectional study of maternal-neonatal pairs at term, we sought to determine the effect of gestational weight gain on neonatal LCPUFA supply. Forty maternal-neonatal pairs of uncomplicated (no gestational hypertension or diabetes) term pregnancies were recruited upon admission to Oregon Health & Science University Labor & Delivery for scheduled cesarean section. Maternal and umbilical cord plasma fatty acid profiles were measured using gas chromatography-mass spectrophotometry. First trimester weight gain was negatively correlated with maternal n-3 LCPUFA ( r = -0.80, P = .0002), and this was not affected by fetal sex. High maternal weight gain in the first trimester was negatively associated with cord n-3 polyunsaturated fatty acid levels ( r = -0.70, P = .03) and placental thickness ( r = -0.69, P = .03) in male, but not female, offspring. High maternal weight gain in the first trimester is associated with a thinner placenta and low levels of n-3 LCPUFA in male offspring. Further study is required to confirm that male offspring are at a higher risk of poor outcomes associated with high maternal weight gain early in pregnancy.

Homoplantaginin modulates insulin sensitivity in endothelial cells by inhibiting inflammation

Recent data have indicated that inflammation plays an important role in the development of insulin resistance. The present study aims at examining the activity of homoplantaginin, a flavonoid from a traditional Chinese medicine Salvia plebeia R. BR., on palmitic acid (PA)-induced insulin sensitivity and the underlying mechanisms of its anti-infammatory properties in the endothelial cells. Pre-treatment of homoplantaginin on human umbilical vein endothelial cells (HUVECs) significantly inhibited PA induced tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA expression, and inhibitory κB kinase beta (IKKβ) and nuclear factor-κB (NF-κB) p65 phosphorylation. To the PA-impaired insulin-dependent tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and decrease in nitric oxide (NO) production, pretreatment of homoplantaginin could effectively reverse the effects of PA. Additionally, homoplantaginin significantly modulated the Ser/Thr phosphorylation of IRS-1, improved phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), and increased NO production in the presence of insulin. Taken together, our results demonstrated that homoplantaginin ameliorates endothelial insulin resistance by inhibiting inflammation and modulating cell signalling via the IKKβ/IRS-1/pAkt/peNOS pathway, suggesting it may be used for the prevention and treatment of endothelial dysfunction associated with insulin resistance.

Effect of palmitic acid and linoleic acid on expression of ICAM-1 and VCAM-1 in human bone marrow endothelial cells (HBMECs)

INTRODUCTION

The amount and type of fatty acids (FAs) in the diet influence the risk of atherosclerosis. Palmitic acid and linoleic acid exist at high levels in Iranian edible oils. In this study, we investigated the effect of palmitic acid and linoleic acid on expression of soluble and cell-associated forms of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in human bone marrow endothelial cells (HBMECs).

MATERIAL AND METHODS

The endothelial cells were induced with bacterial lipopolysaccharide (LPS) or tumor necrosis factor α (TNF-α), and thereafter incubated with palmitic or linoleic acid. The level of soluble and cell-associated VCAM-1 and ICAM-1 were analyzed using ELISA and western blot.

RESULTS

Our findings indicated that palmitic acid up-regulates the expression of ICAM-1 and VCAM-1 in HBMECs when these cells are induced with TNF-α or LPS. In addition, the results suggest that linoleic acid could sustain up-regulated ICAM-1 and VCAM-1 in activated endothelial cells.

CONCLUSIONS

Chronic activation of endothelial cells in the presence of palmitic and linoleic may account for pathogenesis of cardiovascular events. These findings provide further support for the detrimental effects of these fatty acids, especially palmitic acid, in promotion and induction of cardiovascular diseases which are prevalent in the Iranian population.

Trans fatty acids induce vascular inflammation and reduce vascular nitric oxide production in endothelial cells

Intake of trans fatty acids (TFA), which are consumed by eating foods made from partially hydrogenated vegetable oils, is associated with a higher risk of cardiovascular disease. This relation can be explained by many factors including TFA's negative effect on endothelial function and reduced nitric oxide (NO) bioavailability. In this study we investigated the effects of three different TFA (2 common isomers of C18 found in partially hydrogenated vegetable oil and a C18 isomer found from ruminant-derived—dairy products and meat) on endothelial NF-κB activation and nitric oxide (NO) production. Human endothelial cells were treated with increasing concentrations of Elaidic (trans-C18:1 (9 trans)), Linoelaidic (trans-C18:2 (9 trans, 12 trans)), and Transvaccenic (trans-C18:1 (11 trans)) for 3 h. Both Elaidic and Linoelaidic acids were associated with increasing NF-κB activation as measured by IL-6 levels and phosphorylation of IκBα, and impairment of endothelial insulin signaling and NO production, whereas Transvaccenic acid was not associated with these responses. We also measured superoxide production, which has been hypothesized to be necessary in fatty acid-dependent activation of NF-κB. Both Elaidic acid and Linoelaidic acid are associated with increased superoxide production, whereas Transvaccenic acid (which did not induce inflammatory responses) did not increase superoxide production. We observed differential activation of endothelial superoxide production, NF-κB activation, and reduction in NO production by different C18 isomers suggesting that the location and number of trans double bonds effect endothelial NF-κB activation.

Molecular mechanisms by which saturated fatty acids modulate TNF-α expression in mouse macrophage lineage

Many macrophage functions are modulated by fatty acids (FAs), including cytokine release, such as tumor necrosis factor-α (TNF-α). TNF-α is of great interest due to its role in the inflammation process observed in several diseases such as rheumatoid arthritis, atherosclerosis, and obesity. However, the mechanisms by which FA effects occur have not been completely elucidated yet. In this study, we used a mouse monocyte lineage (J774 cells) to evaluate the effect of 50 and 100 μM of saturated (palmitic and stearic acids), monounsaturated (oleic acid) and polyunsaturated (linoleic acid) FAs on TNF-α production. Alterations in gene expression, poly(A) tail length and activation of transcription factors were evaluated. Oleic and linoleic acids, usually known as neutral or pro-inflammatory FA, inhibited LPS-induced TNF-α secretion by the cells. Saturated FAs were potent inducers of TNF-α expression and secretion under basal and inflammatory conditions (in the presence of LPS). Although the effect of the saturated FA was similar, the mechanism involved in each case seem to be distinct, as palmitic acid increased EGR-1 and CREB binding activity and stearic acid increased mRNA poly(A) tail. These results may contribute to the understanding of the molecular mechanisms by which saturated FAs modulate the inflammatory response and may lead to design of associations of dietary and pharmacological strategies to counteract the pathological effects of TNF-α.

The 2008 ESPEN Sir David Cuthbertson Lecture: Fatty acids and inflammation--from the membrane to the nucleus and from the laboratory bench to the clinic

Many chronic conditions involve excessive inflammation that is damaging to host tissues. Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury and infection in some individuals and these can lead, progressively, to sepsis and septic shock. Hyperinflammation is characterised by the production of inflammatory cytokines, eicosanoids and other inflammatory mediators, while the immunosuppression is characterised by impairment of antigen presentation and of certain T cell responses. N-6 fatty acids may contribute to the hyperinflamed and immunosuppressed states. N-3 fatty acids from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid precursor) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, these fatty acids are potentially useful anti-inflammatory agents and may be of benefit in patients with chronic inflammatory diseases or at risk of hyperinflammation and sepsis. An emerging application of n-3 fatty acids is in surgical or critically ill patients where they may be added to parenteral or enteral formulas. Studies to date are suggestive of clinical benefits from these approaches, although more robust data are needed especially in critically ill patients.

Food-derived bioactives as potential regulators of the IL-12/IL-23 pathway implicated in inflammatory bowel diseases

The gene-specific modulation of inflammatory cytokines by food bioactives represents a possible approach to the nutritional or pharmaceutical prevention and treatment of inflammatory bowel disease (IBD). There is evidence for a key role of the interleukin-12beta1/23 receptor (IL-12 Rbeta1/23 R) pathway in IBD, and that reduction of the normal expression of the IL-23 R gene may provide a therapeutic target for this disease. The binding of interleukin-23 (IL-23) to its receptor IL-23 R regulates a newly defined effector T-cell subset, Th17 cells, characterised by the production of interleukin-17 (IL-17) and other cytokines, including tumour necrosis factor-alpha (TNF-alpha). In this study we developed an assay that measured IL-17 and TNF-alpha expression after incubation with specific dietary bioactives in the human T-cell Kit 225. It is anticipated that these changes will reflect differences in IL-23 R production, albeit indirectly. The cell line Kit 225 has similarities to Th17 cells, a subset of T cells producing IL-17 and TNF-alpha, and in initial experiments we demonstrated that the cells express both IL-23 receptor subunits, as well as IL-17 and TNF-alpha genes. Upon verification that stimulation of Kit 225 cells with 1ng/mL IL-23 significantly upregulated IL-17 and TNF-alpha gene expression, and IL-17 production, we supplemented cells with selected food bioactives, caffeic acid phenethyl ester (CAPE), epigallocatechin gallate (EGCG), docosahexaenoic acid (DHA), and linoleic acid (LA), and with phorbol myristate acetate (PMA) and sodium salicylate, used as pro-inflammatory and anti-inflammatory controls, respectively. In both unstimulated cells and after IL-23 stimulation, bioactives modulated the pro-inflammatory cytokines involved in IBD, underlining the possible role of foods in this disease. EGCG and DHA, which significantly inhibited both IL-17 and TNF-alpha expression, appeared particularly interesting.

Co-existence of fatty acids changes in aorta artery and adipose tissue; comparison between CAD and non CAD patients

BACKGROUND

This study was aimed to evaluate composition and possible co-existence of change in fatty acids of aorta artery and adipose tissue in two groups of patients with different degree of atherosclerosis.

METHODS

Twenty-one angiographically documented coronary artery diseases (CAD) patients, and the same numbers of age, sex and body mass index-matched angiographically documented non CAD patients enrolled in this study. They were operated electively for coronary artery bypass grafting (CABG) or aortic valve replacement surgery (AVR), respectively. Small segments of ascending aorta artery and adipose tissue were dissected form the two groups during open heart surgery and subjected to fatty acid analysis.

RESULTS

The results showed that in the CAD group, amounts of saturated and omega6 unsaturated fatty acids were higher, while the percent of monounsaturated and omega3 unsaturated fatty acids were lower than the non CAD patients for both aorta artery and adipose tissue samples. A moderate correlation was seen between amounts of fatty acids in adipose tissue and aorta artery.

CONCLUSION

As there are many reports which show that adipose tissue can only be used as a suitable indicator of dietary intake of exogenous fatty acids (e.g. polyunsaturated and trans fatty acids), our study suggests that modification of fatty acids with endogenous synthesis and metabolism (e.g. saturated and monounsaturated fatty acids) which were observed in both adipose tissue and aorta artery of CAD patients, may be produced during atherogenesis.

Butter feeding enhances TNF-alpha production from macrophages and lymphocyte adherence in murine small intestinal microvessels

BACKGROUND AND AIM

Dietary fat is known to modulate immune functions. Intake of an animal fat-rich diet has been linked to increased risk of inflammation; however, little is known about how animal fat ingestion directly affects intestinal immune function. The objective of this study was to assess the effect of butter feeding on lymphocyte migration in intestinal mucosa and the changes in adhesion molecules and cytokines involved in this effect.

METHODS

T-lymphocytes isolated from the spleen were fluorescence-labeled and injected into recipient mice. Butter was administered into the duodenum, and villus microvessels of the small intestinal mucosa were observed under an intravital microscope. mRNA expression of adhesion molecules and cytokines in the intestinal mucosa were determined by quantitative PCR. The effect of butter feeding on tumor necrosis factor (TNF)-alpha mRNA expression of intestinal macrophages was also determined.

RESULTS

Intraluminal butter administration significantly increased lymphocyte adherence to intestinal microvessels accompanied by increases in expression levels of adhesion molecules ICAM-1, MAdCAM-1 and VCAM-1. This accumulation was significantly attenuated by anti-MAdCAM-1 and anti-ICAM-1 antibodies. Butter administration significantly increased TNF-alpha in the lamina proprial macrophages but not interleukin-6. Anti-TNF-alpha treatment attenuated the enhanced expression of adhesion molecules induced by butter administration.

CONCLUSION

T-lymphocyte adherence to microvessels of the small intestinal mucosa was significantly enhanced after butter ingestion. This enhancement is due to increase in expression levels of adhesion molecules of the intestinal mucosa, which is mediated by TNF-alpha from macrophages in the intestinal lamina propria.

Comparative effects of fatty acids on endothelial inflammatory gene expression

BACKGROUND

Endothelial dysfunction may be related to adverse effects of some dietary fatty acids (FAs). Although in vitro studies have failed to show consistent findings, this may reflect the diverse experimental protocols employed and the limited range of FAs and end points studied.

AIMS

To investigate the effect of dietary FA type (saturated, monounsaturated, n-6 and n-3 polyunsaturated fatty acids), concentration, incubation time and cell stimulation state, on a broad spectrum of endothelial inflammatory gene expression.

METHODS

Using human umbilical vein endothelial cells, with and without stimulation (+/-10 ng/ml TNFalpha), the effects of arachidonic (AA), docosahexaenoic (DHA), eicosapentaenoic (EPA), linoleic (LA), oleic (OA) and palmitic acids (PA) (10, 25 and 100 microM), on the expression of genes encoding a number of inflammatory proteins and transcription factors were assessed by quantitative real time RT-PCR.

RESULTS

Individual FAs differentially affect endothelial inflammatory gene expression in a gene-specific manner. EPA, LA and OA significantly up-regulated MCP-1 gene expression compared to AA (p = 0.001, 0.013, 0.008, respectively) and DHA (p < 0.0005, = 0.004, 0.002, respectively). Furthermore, cell stimulation state and FA incubation time significantly influenced reported FA effects on gene expression.

CONCLUSION

The comparative effects of saturated, monounsaturated, n-6 and n-3 polyunsaturated FAs on endothelial gene expression depend on the specific FA investigated, its length of incubation, cell stimulation state and the gene investigated. These findings may explain existing disparity in the literature.

Regulation of interleukin-2 signaling by fatty acids in human lymphocytes

Docosahexaenoic (DHA; C22:6 n-3), eicosapentaenoic (EPA; C20:5 n-3), palmitic (PA; C16:0), and stearic (SA; C18:0) acids decrease lymphocyte proliferation in concentrations of >50 muM, as observed in our previous study. However, oleic acid (OA; C18:1 n-9) and linoleic acid (LA; C18:2 n-6) increase lymphocyte proliferation at 25 muM. In this study, the effect of these FAs on the interleukin-2 (IL-2) signaling pathway in human lymphocytes was investigated. Cells were isolated from heparinized venous blood of healthy human donors by density-gradient sedimentation. Cells were stimulated with 5 mug/ml concanavalin A and treated with FAs in the absence or presence of IL-2 for 1 hour. CD25-alpha externalization was analyzed by flow cytometry, and Janus kinase 1 (JAK1), JAK3, signal transducer and activator of transcription (STAT) 5, extracellular signal-regulated kinases (ERKs) 1 and 2, Akt, and protein kinase C (PKC)-zeta phosphorylation were analyzed by Western blotting. The expression of CD25-alpha at the cell surface was increased by DHA, SA, and PA but was unaffected by EPA, OA, and LA. PA, SA, DHA, and EPA decreased JAK1, JAK3, STAT5, and Akt phosphorylation induced by IL-2, but OA and LA did not cause any effect. OA and LA increased ERK1/2 phosphorylation, whereas the other FAs caused a marked decrease. PKC-zeta phosphorylation was decreased by OA and LA and was not altered by the remaining FAs. In conclusion, the inhibitory effect of PA, SA, DHA, and EPA on lymphocyte proliferation observed in our previous study was attributable to a decrease in JAK/STAT, ERK, and Akt pathways activated by IL-2. Probably, OA and LA stimulated lymphocyte proliferation by increasing ERK1/2 phosphorylation through PKC-zeta activation. The inhibition of JAK1, JAK3, STAT5, ERK1/2, and Akt phosphorylation caused by DHA, SA, and PA is associated with an alteration of CD25 expression at the cell surface.

Use of fish oil in parenteral nutrition: Rationale and reality

Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury and infection in some individuals and can lead, progressively, to sepsis and septic shock. The hyperinflammation is characterised by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids and other inflammatory mediators, while the immunosuppression is characterised by impairment of antigen presentation and of T-helper lymphocyte type-1 responses. Long-chain n-3 fatty acids from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid substrate and by inhibiting arachidonic acid metabolism) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, long-chain n-3 fatty acids are potentially useful anti-inflammatory agents and may be of benefit in patients at risk of hyperinflammation and sepsis. As a consequence, an emerging application for n-3 fatty acids, in which they may be added to parenteral (or enteral) formulas, is in surgical or critically-ill patients. Parenteral nutrition that includes n-3 fatty acids appears to preserve immune function better than standard formulas and appears to diminish the extent of the inflammatory response. Studies to date are suggestive of clinical benefits from these approaches, especially in patients post surgery, although evidence of clinical benefit in patients with sepsis is emerging.

Low-Density Lipoprotein Modified by Macrophage-Derived Lysosomal Hydrolases Induces Expression and Secretion of IL-8 Via p38 MAPK and NF-κB by Human Monocyte-Derived Macrophages

OBJECTIVE

Modified lipoproteins induce inflammatory reactions in the atherosclerotic arterial wall. We have previously found that macrophages in atherosclerotic lesions secrete lysosomal hydrolases that can modify low-density-lipoprotein (LDL) in vitro to generate "hydrolase-modified LDL" (H-LDL). Here, we studied whether H-LDL exerts inflammatory effects on cultured human macrophages.

METHODS AND RESULTS

Using cytokine cDNA arrays, we found that H-LDL induced expression of IL-8, but not of the anti-inflammatory cytokines IL-10 and transforming growth factor (TGF)-beta, in human monocyte-derived macrophages. H-LDL induced rapid phosphorylation of the p38 mitogen-activated protein kinase (MAPK), nuclear translocation of 2 transcription factors, nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1), and time-dependent secretion of IL-8 from the macrophages. Inhibition of MAPKs and of transcription factors showed that p38 MAPK and NF-kappaB, but not ERK1/2, JNK, or AP-1, were crucial for the H-LDL-induced IL-8 secretion from the macrophages.

CONCLUSIONS

The results show that by activating p38 MAPK and NF-kappaB, macrophage hydrolases modify LDL into biologically active particles capable of triggering the secretion of IL-8 in macrophages. Thus, activated hydrolase-secreting macrophages in atherosclerotic lesions may sustain a proatherogenic extracellular environment by hydrolyzing LDL and triggering it to act in an autocrine or paracrine fashion to induce IL-8 secretion by the plaque macrophages.

Apolipoprotein B: a predictor of inflammatory status in postmenopausal overweight and obese women

AIMS/HYPOTHESIS

Inflammation is implicated in the development of type 2 diabetes and CHD, but the trigger of inflammation is unclear. Although in vitro and animal studies support a role of elevated levels of atherosclerotic lipoproteins in the activation of inflammation, plasma cholesterol cannot predict inflammatory markers in humans. Moreover, the association between inflammatory markers and other traditional risk factors of diabetes and CHD is unclear. To increase our knowledge of in vivo regulation of inflammation, we examined the association between several traditional risk factors and inflammatory markers. We hypothesised that because apolipoprotein B (ApoB) reflects atherogenic particle number, it is the primary predictor of inflammatory status.

SUBJECTS, MATERIALS AND METHODS

We examined the association between several traditional risk factors and plasma high-sensitivity (hs) C-reactive protein (CRP), hsTNF-alpha, soluble TNF receptor 1, IL-6, orosomucoid, haptoglobin and alpha(1)-antitrypsin in 77 non-diabetic overweight and obese postmenopausal women.

RESULTS

The inflammatory markers correlated positively with total and abdominal adiposity, blood pressure, 2-h OGTT glucose, insulin resistance, triglyceride, total/HDL cholesterol, ApoB, ApoB:apolipoprotein A1 (ApoA1) ratio and Framingham CHD risk points. They correlated negatively with ApoA1, and total, LDL and HDL cholesterol. ApoB was an independent predictor of the interindividual variation in IL-6, hsCRP, orosomucoid, haptoglobin and alpha(1)-antitrypsin (R (2) range 8-40%); other risk factors were less predictive. Compared with BMI-matched control subjects, women with hyperapobetalipoproteinaemia (hyperapoB) had higher hsTNF-alpha, IL-6, hsCRP and orosomucoid (increase 17-104%).

CONCLUSIONS/INTERPRETATION

ApoB is the primary predictor of inflammatory markers in postmenopausal overweight and obese women. Given elevated levels of inflammatory markers in hyperapoB women, we hypothesise that hyperapoB women may have an increased risk of developing both CHD and diabetes.

Inflammatory effects of very low-density lipoprotein and fatty acids

High plasma triacylglycerol (triglyceride, TG) levels is a risk factor for atherosclerosis. Very large lipoproteins, such as chylomicrons, alone are not considered atherogenic, but TG-rich remnant lipoproteins can penetrate into the vascular wall. Importantly, accumulating evidence suggests that all TG-rich lipoproteins stimulate cytokine expression in circulating monocytes. Very low-density lipoprotein (VLDL) stimulates monocyte adhesion to endothelial cells and expression of inflammatory genes in macrophages. Furthermore, fatty acids released from large lipoproteins can stimulate both vascular cells and circulating monocytes. It is likely that fatty acids released from TG-rich lipoproteins contribute to atherogenesis, but the role of fatty acids in ischemic heart disease is not as direct as that of cholesterol. Fatty acids influence plasma lipoprotein levels and either stimulate or suppress numerous cellular functions relevant to atherogenesis. While certain n-3 fatty acids are good for health, most other medium- to long-chain fatty acids appear to promote inflammation in cell culture studies and need to be studied further. Nevertheless, the existing evidence supports the general conclusion that TG-rich lipoproteins and fatty acids greatly accelerate the progression of atherosclerosis. This may be because of their inflammatory effects.

Comparison of fatty acid profiles of aorta and internal mammary arteries in patients with coronary artery disease

BACKGROUND

Atherosclerosis represents the principal cause of death in the many societies. Since few data have been published about the composition of fatty acids in atherosclerotic arteries such as the aorta comparing to the non affected internal mammary artery which is used for aortocoronary bypass grafting, we compared the fatty acid profiles of atherosclerotic aorta and internal mammary arteries in human individuals.

METHODS

Twenty-one angiographically documented coronary artery disease (CAD) patients who were admitted to the open heart surgery division enrolled in this study. They were operated electively for coronary artery bypass grafting surgery (CABG). Small segments of ascending aorta and internal mammary arteries were sampled during open heart surgery. The samples were subjected to lipid extraction and fatty acid analysis by high performance liquid chromatography.

RESULTS

The results showed that different fatty acid profiles were seen in the aorta and internal mammary arteries. The atherosclerotic aorta contained lower amounts of unsaturated fatty acids (including trans isomer of oleic acid) and higher proportions of saturated fats comparing to the internal mammary. In the aorta also, the amounts of omega6 series of fatty acids were more and levels of omega3 fats were less than the internal mammary.

CONCLUSION

This study suggests that modification of fatty acids may play a role during atherogenesis.

Linoleic acid increases lectin-like oxidized LDL receptor-1 (LOX-1) expression in human aortic endothelial cells

Results from in vitro studies suggest that selected fatty acids, and especially linoleic acid (LA), can elicit endothelial dysfunction (ED). Because LA is increased in all LDL subfractions in patients with type 2 diabetes, this alteration may contribute to ED associated with diabetes. Lectin-like oxidized LDL receptor-1 (LOX-1) is the major endothelial receptor for oxidized LDL (oxLDL), and uptake of oxLDL through LOX-1 induces ED. To evaluate whether LA may contribute to the upregulation of endothelial LOX-1 in diabetes, we studied the effect of LA on LOX-1 expression in cultured human aortic endothelial cells (HAECs). Treatment of HAECs with LA increased, in a time- and dose-dependent manner, endothelial LOX-1 protein expression. Pretreatment of HAECs with antioxidants and inhibitors of NADPH oxidase, protein kinase C (PKC), and nuclear factor-kappaB (NF-kappaB) inhibited the stimulatory effect of LA on LOX-1 protein expression. Furthermore, in LA-treated HAECs, increased expression of classic PKC isoforms was observed. LA also led to a significant increase in LOX-1 gene expression and enhanced the binding of nuclear proteins extracted from HAECs to the NF-kappaB regulatory element of the LOX-1 gene promoter. Finally, LA enhanced, through LOX-1, oxLDL uptake by endothelial cells. Overall, these results demonstrate that LA enhances endothelial LOX-1 expression through oxidative stress-sensitive and PKC-dependent pathways. This effect seems to be exerted at the transcriptional level and to involve the activation of NF-kappaB. Upregulation of LOX-1 by LA may contribute to ED associated with type 2 diabetes.

n-3 fatty acids, inflammation, and immunity--relevance to postsurgical and critically ill patients

Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury, and infection in some individuals and these can lead, progressively, to sepsis and septic shock. The hyperinflammation is characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids, and other inflammatory mediators, while the immunosuppression is characterized by impairment of antigen presentation and of T helper cell type-1 responses. Long-chain n-3 FA from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid substrate and by inhibiting arachidonic acid metabolism) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, long-chain n-3 FA are potentially useful anti-inflammatory agents and may be of benefit in patients at risk of developing sepsis. As such, an emerging application of n-3 FA is in surgical or critically ill patients where they may be added to parenteral or enteral formulas. Parenteral or enteral nutrition including n-3 FA appears to preserve immune function better than standard formulas and appears to partly prevent some aspects of the inflammatory response. Studies to date are suggestive of clinical benefits from these approaches, especially in postsurgical patients.

Polyunsaturated Fatty Acids and Cardiovascular Health

Epidemiologic studies have shown a beneficial association between polyunsaturated fatty acid (PUFA), specifically linoleic acid (C18:2, n-6), intake and cardiovascular disease morbidity and mortality. Clinical studies have shown that n-6 PUFAs have the most potent cholesterol-lowering effects of the individual fatty acid classes, and emerging evidence suggests that PUFAs have favorable effects on postprandial lipemia. However, some studies suggest that high intakes of linoleic acid may have adverse effects on proinflammatory cytokines and adhesion molecules. Research is needed to establish the optimal level of dietary PUFAs that maximally affects the greatest number of health risk factors.

Triacylglycerol-rich lipoprotein–gene interactions in endothelial cells

Lipoproteins such as LDL (low-density lipoprotein) and oxidized LDL have potentially adverse effects on endothelial cells due to their ability to activate pro-inflammatory pathways regulated via the transcription factor NF-κB (nuclear factor κB). Triacylglycerol-rich lipoproteins (the chylomicrons, very-low-density lipoprotein and their respective remnant particles) have also been implicated in the induction of a pro-inflammatory phenotype and up-regulation of adhesion molecule expression. Although early studies supported the proposal that LPL (lipoprotein lipase)-mediated hydrolysis of TRLs (triglyceride-rich lipoproteins) at the endothelium could activate the NFκB pathway, more recent studies provide evidence of pro- and anti-inflammatory responses when cells are exposed to fatty acids or TRL particles. A large number of genes are up- and down-regulated when cells are exposed to TRL, with the net effect reflecting receptor- and nonreceptor-mediated pathways that are activated or inhibited depending on fatty acid type, the lipid and apolipoprotein composition of the TRL and the presence or absence of LPL. Early concepts of TRL particles as essentially pro-inflammatory stimuli to the endothelium provide an overly simplistic view of their impact on the vascular compartment.

Linoleic acid, but not oleic acid, upregulates the production of interleukin-8 by human intestinal smooth muscle cells isolated from patients with Crohn's disease

BACKGROUND & AIMS

Crohn's disease is a chronic inflammatory bowel disease (IBD) of unknown etiology. In this study, we investigated the hypothesis that dietary fatty acids, linoleic acid (LA) and oleic acid (OA), could be involved in the inflammatory response through stimulation of the neutrophil chemokine, IL-8.

METHODS

Human intestinal smooth muscle (HISM) cells were isolated from normal patients and patients with Crohn's disease and cultured for 24h with LA or OA in the presence or absence of oxidative stress. The concentrations of IL-8 were measured in the media and cellular oxidative stress was quantitated by measurement of thiobarbituric acid reactive substances (TBARSs).

RESULTS

Spontaneous production of IL-8 was significantly higher in HISM cells isolated from Crohn's bowel compared to control bowel. LA caused a marked, nine-fold, increase in IL-8 secretion by Crohn's cells, an effect that could be simulated in normal HISM cells by co-incubation of LA with an oxidizing solution (Ox) composed of hypoxanthine+xanthine oxidase+FeSO(4) (OxLA). These effects were inhibited by vitamins C and E. Treatment of Crohn's cells with OxLA did not further increase IL-8 over that of LA alone. The effect of LA alone was not associated with an increase in cellular oxidative stress as quantitated by TBARSs. In contrast to the results with LA, treatment with OA or OxOA did not increase IL-8 in either normal or Crohn's cells. In addition, OA protected Crohn's cells from the increase in TBARSs induced by Ox. In contrast to IL-8, spontaneous production of monocyte chemotactic protein (MCP-1) was significantly lower in Crohn's HISM cells as compared to normal cells and exposure to OxLA did not increase its production.

CONCLUSIONS

LA, but not OA, increased the production of IL-8 by HISM cells. These results suggest that replacement of LA by OA in the diet of Crohn's patients and increased intake of a diet rich in antioxidants could be beneficial in decreasing inflammatory activity in Crohn's disease.

Effect of a Dietary n-6 Polyunsaturated Fatty Acid Supplement on Distinct Immune Functions of Goats

The aim of this study was to investigate whether dietary n-6 polyunsaturated fatty acids (PUFA) alter immune functions as lymphocyte blastogenesis, expression of lymphocyte and monocyte markers, and cell adhesion molecules of the integrin family in goats. Dutch White castrated male goats received a diet either rich in olive oil (control group, n = 4) or rich in corn oil (test group, n = 4) over a period of 3 weeks. The animals in the test group had significantly higher linoleic acid (LA, 18:2n-6) levels in plasma on days 7, 14 and 21 of the diet than control animals. This was also true for washed erythrocyte membranes at day 21. A significant reduction in the percentage of alpha-4 integrin (CD49d) expressing lymphocytes was observed in goats fed LA rich corn oil at day 21. However, no changes were observed in either lymphocyte proliferative responses to ConA and PHA or the expression of other lymphocyte/monocyte markers. In conclusion, feeding corn oil rich in LA caused significant increases in the proportion of LA in the fatty acid composition of plasma and erythrocyte membranes and was accompanied by a significant decrease of the adhesion molecule alpha-4 integrin (CD49d) on lymphocytes but not on monocytes.

Free fatty acids trigger apoptosis and inhibit cell cycle progression in human vascular endothelial cells

Plasma free fatty acid (FFA) concentrations are increased in states of insulin resistance and impair endothelial function. Because the underlying mechanisms are largely unknown, we examined selected, purified FFAs' (100-300 micromol/l, 24-48 h) action on apoptosis, cell cycle distribution, and associated gene/protein expression in human umbilical vein endothelial cells (HUVECs). Stearic acid, but not oleic acid, time and concentration dependently increased endothelial apoptosis by fivefold (n=6, P<0.01), whereas polyunsaturated FFAs (PUFAs; linoleic, gamma-linolenic, and arachidonic acid) exerted proapoptotic activity only at 300 micromol/l (P<0.05). Proapoptotic FFA action increased with FFAs' number of double bonds and with protein expression of the apoptosis promotor bak. The G0/G1 cell cycle arrest (n=6, P<0.05) induced by stearic acid (+14%) and PUFAs (+30%) is reflected by up-regulation of p21(WAF-1/Cip1). In addition, all FFAs concentration dependently reduced (P<0.05) gene/protein expression of clusterin (-54%), NF-kappaB's inhibitor, IkappaBalpha (-50%), endothelin-1 (-44%), and endothelial NO synthase (-44%). Plasma samples obtained from individuals with elevated plasma FFAs (372+/-22 micromol/l) increased endothelial apoptosis by 4.2-fold (P<0.001, n=10) compared with intra-individually matched low plasma FFA (56+/-21 micromol/l) conditions, underlining the results obtained by defined FFA stimulation. In conclusion, FFA structure differently affects endothelial cell proliferation and apoptosis, both representing key factors in the development of micro- and macrovascular dysfunction.

Oxidative stress reproduces placental abnormalities of preeclampsia

OBJECTIVE

The activities of placental superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but not catalase, are lower than normal in preeclampsia, which could contribute to the uncontrolled placental production of lipid peroxides and thromboxane (TX). Oxidative stress, hyperlipidemia and increased iron levels in the maternal compartment in preeclampsia could be responsible for these placental changes by causing oxidative stress in the placenta.

METHODS

We tested this possibility in vitro by exposing a trophoblast-like cell line, ED27, to a combination of linoleic acid (LA, 90 microM) and an oxidizing solution composed of hypoxanthine, xanthine oxidase and ferrous sulfate (OxLA) for 6 days. For these studies, the cells were treated with dexamethasone (10-8 M) for the first 72 hr. This was done to differentiate the cells into a phenotype more like syncytiotrophoblast cells as evidenced by production of beta-human chorionic gonadotropin (beta-hCG).

RESULTS

After 6 days of exposure to OxLA, the activities of SOD and GSH-Px were significantly decreased as compared to exposure to LA alone. In contrast, catalase activity was increased by OxLA. The OxLA-induced decreases in SOD and GSH-Px activities were attenuated by deferoxamine, an iron chelator, suggesting a role for Fe2+ in the decreased activities. Compared to LA, OxLA significantly increased TX secretion and lipid peroxidation in cells and media at 2, 4 and 6 days. Deferoxamine inhibited the OxLA-induced increase in lipid peroxidation, but not the increase in TX. Isolation of trophoblast cells and villous core tissue from term placentas verified that antioxidant enzyme activity was localized primarily to the trophoblast cell compartment lending validity to the in vitro findings.

CONCLUSIONS

These data mimic the changes in placental SOD, GSH-Px, catalase, TX and lipid peroxidation that occur in preeclampsia suggesting that maternal hyperlipidemia and increased iron levels may be responsible for placental oxidative stress and abnormalities in antioxidants and thromboxane.

Increased vascular endothelial cell production of interleukin-6 in severe preeclampsia

OBJECTIVE

The purpose of this study was to determine whether plasma from women with severe preeclampsia stimulates the production of endothelial cell interleukin-6 production and whether vitamin E could inhibit this process.

STUDY DESIGN

Human umbilical vein endothelial cells were cultured in the presence of 5% plasma from women with severe preeclampsia (n = 12) or healthy pregnant women at term (n = 12), with or without 50 micromol/L vitamin E. Levels of interleukin-6 in plasma and human umbilical vein endothelial cell-conditioned media were measured by enzyme-linked immunosorbent assay.

RESULTS

Interleukin-6 levels were elevated 5-fold in preeclamptic plasma compared with normal pregnant plasma (P <.05). Human umbilical vein endothelial cell interleukin-6 production was increased 25% by preeclamptic plasma compared with normal pregnant plasma (P <.005), and increased interleukin-6 production by preeclamptic plasma was inhibited by vitamin E.

CONCLUSION

Endothelial cell activation by preeclamptic plasma stimulates interleukin-6 production, which is inhibited by vitamin E. These findings provide a potential cellular mechanism for the beneficial effects of antioxidant therapy in preeclampsia.

Serine phosphorylation of insulin receptor substrate 1 by inhibitor kappa B kinase complex

Insulin resistance contributes importantly to the pathophysiology of type 2 diabetes mellitus. One mechanism mediating insulin resistance may involve the phosphorylation of serine residues in insulin receptor substrate-1 (IRS-1), leading to impairment in the ability of IRS-1 to activate downstream phosphatidylinositol 3-kinase-dependent pathways. Insulin-resistant states and serine phosphorylation of IRS-1 are associated with the activation of the inhibitor kappaB kinase (IKK) complex. However, the precise molecular mechanisms by which IKK may contribute to the development of insulin resistance are not well understood. In this study, using phosphospecific antibodies against rat IRS-1 phosphorylated at Ser(307) (equivalent to Ser(312) in human IRS-1), we observed serine phosphorylation of IRS-1 in response to TNF-alpha or calyculin A treatment that paralleled surrogate markers for IKK activation. The phosphorylation of human IRS-1 at Ser(312) in response to tumor necrosis factor-alpha was significantly reduced in cells pretreated with the IKK inhibitor 15 deoxy-prostaglandin J(2) as well as in cells derived from IKK knock-out mice. We observed interactions between endogenous IRS-1 and IKK in intact cells using a co-immunoprecipitation approach. Moreover, this interaction between IRS-1 and IKK in the basal state was reduced upon IKK activation and increased serine phosphorylation of IRS-1. Data from in vitro kinase assays using recombinant IRS-1 as a substrate were consistent with the ability of IRS-1 to function as a direct substrate for IKK with multiple serine phosphorylation sites in addition to Ser(312). Taken together, our data suggest that IRS-1 is a novel direct substrate for IKK and that phosphorylation of IRS-1 at Ser(312) (and other sites) by IKK may contribute to the insulin resistance mediated by activation of inflammatory pathways.

Enzymatically modified nonoxidized low-density lipoprotein induces interleukin-8 in human endothelial cells: role of free fatty acids

BACKGROUND

Treatment of low-density lipoprotein (LDL) with a protease and cholesterolesterase transforms the lipoprotein to an entity that resembles lipoprotein particles in atherosclerotic lesions, which have a high content of free cholesterol, reflecting extensive de-esterification in the intima. Because de-esterification would occur beneath the endothelium, we examined the effects of enzymatically modified LDL (E-LDL) on cultured endothelial cells.

METHODS AND RESULTS

Incubation of endothelial cells with E-LDL provoked selective accumulation of interleukin (IL)-8 mRNA and production of the cytokine. Chemical analyses and depletion experiments indicated that the effect was caused by the presence of free fatty acids in the altered lipoprotein. Reconstitution studies demonstrated that the oleic and linoleic acids associated with E-LDL are particularly effective IL-8 inducers. The effects of E-LDL on endothelial cells could be abrogated with albumin.

CONCLUSION

IL-8 is required for rolling monocytes to adhere firmly to the endothelium; thus, the findings reveal a link between subendothelial entrapment of LDL, cleavage of cholesterol esters, and monocyte recruitment into the lesion.

Linoleic acid induces MCP-1 gene expression in human microvascular endothelial cells through an oxidative mechanism

Linoleic acid is a dietary fatty acid that appears to play an important role in activation of the vascular endothelium under a variety of pathological conditions, including development of atherosclerosis or cancer metastasis. Evidence indicates that inflammatory responses may be an underlying cause of endothelial cell pathology induced by linoleic acid. However, the profile of inflammatory mediators and the potential mechanisms involved in inflammatory reactions stimulated by the exposure to linoleic acid are not fully understood. The present study focused on the mechanisms of linoleic acid-induced expression of monocyte chemoattractant protein-1 (MCP-1) gene in human microvascular endothelial cells (HMEC-1). Treatment of HMEC-1 with increasing doses of linoleic acid markedly activated an oxidative stress-responsive transcription factor, nuclear factor-kappaB (NF-kappaB). In addition, exposure to linoleic acid induced a time- and concentration-dependent overexpression of the MCP-1 gene. Increased MCP-1 mRNA levels were observed in HMEC-1 treated with linoleic acid at doses as low as 10 &mgr;M. Linoleic acid-induced overexpression of the MCP-1 gene was associated with a significant elevation of MCP-1 protein levels. Most importantly, preexposure of HMEC-1 to antioxidants, such as pyrrolidine dithiocarbamate (PDTC) or N-acetylcysteine (NAC), attenuated linoleic acid-induced MCP-1 mRNA expression. The obtained results indicate that linoleic acid triggers MCP-1 gene expression in human microvascular endothelial cells through oxidative stress/redox-related mechanisms.

High-Energy Diets, Fatty Acids and Endothelial Cell Function: Implications for Atherosclerosis

Diets high in fat and/or calories can lead to hypertriglyceridemia and postprandial lipemia and thus are considered a risk factor for the development of atherosclerosis. Plasma chylomicron levels are elevated in humans after consuming a high-fat meal, and hepatic synthesis of VLDL is increased when caloric intake is in excess of body needs. High lipoprotein lipase activity and subsequent hydrolysis of triglyceride-rich lipoproteins may be an important source of elevated concentrations of fatty acid anions in the proximity to the endothelium and hence a major risk factor for atherosclerosis. We have shown that selected fatty acids, as well as lipoprotein lipase-derived remnants of lipoproteins isolated from hypertriglyceridemic subjects, can activate vascular endothelial cells and disrupt endothelial integrity. Our studies suggest that omega-6 fatty acids, and especially linoleic acid, cause endothelial cell dysfunction most markedly as well as can potentiate TNF-mediated endothelial cell injury. We propose that high-energy diets, and especially diets rich in linoleic acid, are atherogenic by contributing to an imbalance in cellular oxidative stress/antioxidant status of the endothelium, which can lead to activation of oxidative stress-responsive transcription factors, inflammatory cytokine production and the expression of adhesion molecules. Our data also suggest that nutrients, which have antioxidant and/or membrane stabilizing properties, can protect endothelial cells. These findings contribute to the understanding of the interactive role of high fat/calorie diets and subsequent hypertriglyceridemia with inflammatory components and nutrients that exhibit antiatherogenic properties in the development of atherosclerosis. Moreover, results from our research further support the concept that high-fat/calorie diets and associated postprandial hypertriglyceridemia are significant risk factors for atherosclerosis.