Effects of EPA and DHA on proliferation, cytokine production, and gene expression in Raji cells

Differential impact of eicosapentaenoic acid and docosahexaenoic acid in an animal model of Alzheimer's disease

Dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFA) improves cognitive performance in several animal models of Alzheimer's disease (AD), an effect often associated with reduced amyloid-beta (Aβ) and/or tau pathologies. However, it remains unclear to what extent eicosapentaenoic (EPA) provides additional benefits compared to docosahexaenoic acid (DHA). Here, male and female 3xTg-AD mice were fed for 3 months (13 to 16 months of age) the following diets: (1) control (no DHA/EPA), (2) DHA (1.1g/kg) and low EPA (0.4g/kg), or (3) DHA (0.9g/kg) with high EPA (9.2g/kg). The DHA and DHA+EPA diets respectively increased DHA by 19% and 8% in the frontal cortex of 3xTg-AD mice, compared to controls. Levels of EPA, which were below the detection limit after the control diet, reached 0.14% and 0.29% of total brain fatty acids after the DHA and DHA+EPA diet, respectively. DHA and DHA+EPA diets lowered brain arachidonic acid (ARA) levels and the n-6:n-3 docosapentaenoic acid (DPA) ratio. Brain uptake of free 14C-DHA measured through intracarotid brain perfusion, but not of 14C-EPA, was lower in 3xTg-AD compared to NonTg mice. DHA and DHA+EPA diets in 3xTg-AD mice reduced cortical soluble phosphorylated tau (pS202) (-34% high-DHA, -34% DHA+EPA, p<0.05) while increasing p21 activated kinase (+58% and +83%, p<0.001; respectively). High EPA intake lowered insoluble phosphorylated tau (-31% versus DHA, p<0.05). No diet effect on Aβ levels was observed. In conclusion, dietary intake of DHA and EPA leads to differential changes in brain PUFA while altering cerebral biomarkers consistent with beneficial effects against AD-like neuropathology.

Impact of cow, buffalo, goat or camel milk consumption on oxidative stress, inflammation and immune response post weaning time

Milk is a whitish liquid that is secreted from mammary glands; and considered as the primary source of nutrition for newborns since they are not able to digest solid food. However, it contains primary nutrients, as well as growth and immune factors. Early weaning is a critical issue that face women and their babies in developing countries. To avoid infant malnutrition, they tend to use other milk types instead of baby formula. Therefore, the present study aimed to evaluate the impact of cow, buffalo, goat or camel milk consumption on oxidative stress, inflammation and immune response in male and female Sprague Dawley rats post weaning time. The amino acids, fatty acids, minerals and vitamins in the tested milk types were evaluated. Animals were divided into 5 groups (control, cow, buffalo, goat and camel milk administrated groups) (10 rats/group); each animal was administrated by 3.4 ml/day. Rats were administered with milk for 6 weeks; at the end of the 5th week, five animals of each group were isolated and the remaining five animals were immunized with sheep red blood cells (SRBCs) and kept for another week to mount immune response. The effect of different milk types on rats' immune response towards SRBCs was evaluated through pro-inflammatory cytokines, antioxidants, ESR and CRP measurement; together, with the histopathological examination of spleen samples and hemagglutination assay. Camel milk consumption reduced oxidative stress and inflammation in spleen that resulted from SRBCs immunization; in addition to, B cell stimulation that was apparent from the high level of anti-SRBCs antibodies. Camel milk is recommended for newborn consumption, due to its high-water content, unsaturated fatty acids, and vitamin C, as well as low lactose and fat content.

Lipid metabolism in regulation of B cell development and autoimmunity

B cells play an important role in adaptive immunity and participate in the process of humoral immunity mainly by secreting antibodies. The entire development and differentiation process of B cells occurs in multiple microenvironments and is regulated by a variety of environmental factors and immune signals. Differentiation biases or disfunction of B cells participate in the process of many autoimmune diseases. Emerging studies report the impact of altered metabolism in B cell biology, including lipid metabolism. Here, we discuss how extracellular lipid environment and metabolites, membrane lipid-related components, and lipid synthesis and catabolism programs coordinate B cell biology and describe the crosstalk of lipid metabolic programs with signal transduction pathways and transcription factors. We conclude with a summary of therapeutic targets for B cell lipid metabolism and signaling in autoimmune diseases and discuss important future directions.

A novel in vitro approach to test the effectiveness of fish oil in ameliorating type 1 diabetes

Diabetes type 1 (T1D) characterized by destruction of pancreatic β-cells results in inadequate insulin production and hyperglycaemia. Generation of reactive oxygen species and glycosylation end-products stimulates toxic impacts on T1D. Dietary w-3 fatty acids present in Fish oil (FO) might be helpful in the prevention of oxidative stress and lipid peroxidation, thus, beneficial against T1D. But how the cellular secretion from β-cells under influence of FO affects the glucose homeostasis of peri-pancreatic cells is poorly understood. In the current study, we aimed to introduce an in vitro model for T1D and evaluate its effectiveness in respect of alloxan treatment to pancreatic Min6 cells. We use alloxan in the Min6 pancreatic β-cell line to induce cellular damage related to T1D. Further treatment with FO was seen to prevent cell death by alloxan and induce mRNA expression of both insulin 1 and insulin 2 isoforms under low-glucose conditions. From the first part of the study, it is clear that FO is effective to recover Min6 cells from the destructive effect of alloxan, and it worked best when given along with alloxan or given after alloxan treatment regime. FO-induced secretion of molecules from Min6 was clearly shown to regulate mRNA expression of key enzymes of carbohydrate metabolism in peri-pancreatic cell types. This is a pilot study showing that an improved in vitro approach of using Min6 along with muscle cells (C2C12) and adipose tissue cells (3T3-L1) together to understand the crosstalk of molecules could be used to check the efficacy of an anti-diabetic drug.

Ropivacaine inhibits wound healing by suppressing the proliferation and migration of keratinocytes via the PI3K/AKT/mTOR Pathway

Background

After surgery, millions of people suffer from delayed healing or wound dehiscence with subsequent severe complications, even death. Previous studies have reported that ropivacaine exhibits anti-proliferative and anti-migratory activities on numerous cells. Whether ropivacaine is able to influence the proliferation and migration of keratinocytes is still unclear. This study aimed to investigate the effect of ropivacaine on keratinocytes and its underlying molecular mechanism.

Methods

Adult male Sprague–Dawley rats were allocated to establish wound healing models with or without 0.75% ropivacaine treatment and assessed the epidermal thickness by HE staining. HaCaT cells were cultured to evaluate the effect of ropivacaine on wound healing. The cell proliferation, apoptosis status and migration were detected in vitro. Moreover, western blotting was used to examine expression to with PI3K/AKT/mTOR signaling pathways for molecular studies and the changes in inflammatory factors (IL-6, IL-10, TNF-α) were detected by ELISA.

Results

In the present study, we found that ropivacaine delayed wound closure in vivo. In vitro experiments, it was demonstrated that ropivacaine significantly inhibited the proliferation and migration of HaCaT cells via the suppression of PI3K/AKT/mTOR signaling pathway. Activation of PI3K/AKT/mTOR signaling pathway reversed the effects of ropivacaine on the proliferation and migration of HaCaT cells. Furthermore, ropivacaine contributed to the release of pro-inflammatory cytokines (IL-6 and TNF-α) and inhibited the secretion of anti-inflammatory cytokines of keratinocytes (IL-10).

Conclusions

Our research demonstrated that ropivacaine treatment showed a more decreased wound closure rate. Mechanistically, we found that ropivacaine suppressed the proliferation and migration of keratinocytes and altered the expression of cytokines by inhibiting PI3K/AKT/mTOR pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01646-0.

Metabolomic Changes in Naturally MAP-Infected Holstein-Friesian Heifers Indicate Immunologically Related Biochemical Reprogramming

Johne’s disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), causes weight loss, diarrhoea, and reduced milk yields in clinically infected cattle. Asymptomatic, subclinically infected cattle shed MAP bacteria but are frequently not detected by diagnostic tests. Herein, we compare the metabolite profiles of sera from subclinically infected Holstein–Friesian heifers and antibody binding to selected MAP antigens. The study used biobanked serum samples from 10 naturally MAP-infected and 10 control heifers, sampled monthly from ~1 to 19 months of age. Sera were assessed using flow infusion electrospray–high-resolution mass spectrometry (FIE–HRMS) on a Q Exactive hybrid quadrupole–Orbitrap mass spectrometer for high-throughput, sensitive, non-targeted metabolite fingerprinting. Partial least-squares discriminant analyses (PLS-DA) and hierarchical cluster analysis (HCA) of the data discriminated between naturally MAP-infected and control heifers. In total, 33 metabolites that differentially accumulated in naturally MAP-infected heifers compared to controls were identified. Five were significantly elevated within MAP-infected heifers throughout the study, i.e., leukotriene B4, bicyclo prostaglandin E2 (bicyclo PGE2), itaconic acid, 2-hydroxyglutaric acid and N6-acetyl-L-lysine. These findings highlight the potential of metabolomics in the identification of novel MAP diagnostic markers and particular biochemical pathways, which may provide insights into the bovine immune response to MAP.

Lipid Source and Peroxidation Status Alter Immune Cell Recruitment in Broiler Chicken Ileum

BACKGROUND

Restaurant oil in poultry diets increases energy content, reduces production costs, and promotes sustainability within the food supply chain. However, variable oil composition and heating temperatures among restaurant oil sources can impact broiler chicken health due to heat-induced lipid modifications.

OBJECTIVES

A 21-d experiment was conducted to evaluate ileal morphology, liver cytokine gene expression, and ileal immune cell populations in broilers fed control or peroxidized lipids with varying chain and saturation characteristics.

METHODS

Day-old broilers were housed in battery cages (5 birds per cage) and fed diets containing 5% control or peroxidized oils. Eight diets were randomly assigned in a 4 × 2 factorial arrangement consisting of oil source (palm, soybean, flaxseed, or fish) and peroxidation status (control or peroxidized). At day 21, samples were collected for ileal histomorphology [villus height (VH), crypt depth (CrD), and the VH:CrD ratio], and liver cytokine expression (qPCR). Ileum cytokine expression and T-cell markers were analyzed by RNAscope in situ hybridization (ISH). Data were analyzed as a mixed model (SAS 9.4) with fixed effects of lipid source, peroxidation, and lipid × peroxidation interaction.

RESULTS

CD3+ T-cells in the ileum decreased 16.2% due to peroxidation (P = 0.001) with 30.3% reductions observed in birds fed peroxidized flaxseed oil (P = 0.01). Peroxidation increased IL6+ and IL1B+ cells by 62.0% and 40.3%, respectively (P = 0.01). Soybean oil increased IFNG+ cells by 55.1% compared with palm oil, regardless of peroxidation status (P = 0.007). Lipid source and peroxidation did not alter ileal histomorphology or liver cytokine expression.

CONCLUSIONS

Lipid peroxidation increased ileal IL1B and IL6 in broiler chickens, whereas soybean oil diets increased IFNG. Generally, peroxidation decreased overall CD3+ T-cell populations, suggesting impaired T-cell presence or recruitment. These results identify potential immunomodulatory lipid profiles in restaurant oil while supporting RNAscope-ISH as a method to describe avian tissue-level immune responses.

Impact of 17β-HSD12, the 3-ketoacyl-CoA reductase of long-chain fatty acid synthesis, on breast cancer cell proliferation and migration

Metabolic reprogramming of tumor cells involves upregulation of fatty acid (FA) synthesis to support high bioenergetic demands and membrane synthesis. This has been shown for cytosolic synthesis of FAs with up to 16 carbon atoms. Synthesis of long-chain fatty acids (LCFAs), including ω-6 and ω-3 polyunsaturated FAs, takes place at the endoplasmic reticulum. Despite increasing evidence for an important role of LCFAs in cancer, the impact of their synthesis in cancer cell growth has scarcely been studied. Here, we demonstrated that silencing of 17β-hydroxysteroid dehydrogenase type 12 (17β-HSD12), essentially catalyzing the 3-ketoacyl-CoA reduction step in LCFA production, modulates proliferation and migration of breast cancer cells in a cell line-dependent manner. Increased proliferation and migration after 17β-HSD12 knockdown were partly mediated by metabolism of arachidonic acid towards COX2 and CYP1B1-derived eicosanoids. Decreased proliferation was rescued by increased glucose concentration and was preceded by reduced ATP production through oxidative phosphorylation and spare respiratory capacity. In addition, 17β-HSD12 silencing was accompanied by alterations in unfolded protein response, including a decrease in CHOP expression and increase in eIF2α activation and the folding chaperone ERp44. Our study highlights the significance of LCFA biosynthesis for tumor cell physiology and unveils unknown aspects of breast cancer cell heterogeneity.

The Influence of Dietary Fatty Acids on Immune Responses

Diet-derived fatty acids (FAs) are essential sources of energy and fundamental structural components of cells. They also play important roles in the modulation of immune responses in health and disease. Saturated and unsaturated FAs influence the effector and regulatory functions of innate and adaptive immune cells by changing membrane composition and fluidity and by acting through specific receptors. Impaired balance of saturated/unsaturated FAs, as well as n-6/n-3 polyunsaturated FAs has significant consequences on immune system homeostasis, contributing to the development of many allergic, autoimmune, and metabolic diseases. In this paper, we discuss up-to-date knowledge and the clinical relevance of the influence of dietary FAs on the biology, homeostasis, and functions of epithelial cells, macrophages, dendritic cells, neutrophils, innate lymphoid cells, T cells and B cells. Additionally, we review the effects of dietary FAs on the pathogenesis of many diseases, including asthma, allergic rhinitis, food allergy, atopic dermatitis, rheumatoid arthritis, multiple sclerosis as well as type 1 and 2 diabetes.

The highly unnatural fatty acid profile of cells in culture

The fatty acid profile of cells in culture are unlike those of natural cells with twice the monounsaturated (MUFA) and half the polyunsaturated fatty acids (PUFA) level (Mol%). This is not due to cell lines primarily being derived from cancers but is due to limited access to lipid and an inability to make PUFA de novo as vertebrate cells. Classic culture methods use media with 10% serum (the only exogenous source of lipid). Fetal bovine serum (FBS), the serum of choice has a low level of lipid and cholesterol compared to other sera and at 10% of media provides 2-3% of the fatty acid and cholesterol, 1% of the PUFA and 0.3% of the essential fatty acid linoleic acid (18:2n-6) available to cells in the body. Since vertebrate cell lines cannot make PUFA they synthesise MUFA, offsetting their PUFA deficit and reducing their fatty acid diversity. Stem and primary cells in culture appear to be similarly affected, with a rapid loss of their natural fatty acid compositions. The unnatural lipid composition of cells in culture has substantial implications for examining natural stems cell in culture, and for investigations of cellular mechanisms using cell lines based on the pervasive influence of fats.

Effects of Omega-3 Fatty Acids on Immune Cells

Alterations on the immune system caused by omega-3 fatty acids have been described for 30 years. This family of polyunsaturated fatty acids exerts major alterations on the activation of cells from both the innate and the adaptive immune system, although the mechanisms for such regulation are diverse. First, as a constitutive part of the cellular membrane, omega-3 fatty acids can regulate cellular membrane properties, such as membrane fluidity or complex assembly in lipid rafts. In recent years, however, a new role for omega-3 fatty acids and their derivatives as signaling molecules has emerged. In this review, we describe the latest findings describing the effects of omega-3 fatty acids on different cells from the immune system and their possible molecular mechanisms.

Topical application of omega-3-, omega-6-, and omega-9-rich oil emulsions for cutaneous wound healing in rats

Wound healing is a physiological event that generates reconstitution and restoration of granulation tissue that ends with scar formation. As omega fatty acids are part of membrane phospholipids and participate in the inflammatory response, we investigated the effects of omega-3, omega-6, and omega-9 fatty acids in the form of oils on wound healing. Linseed (LO), evening primrose (EPO), and olive oils (OO) rich in omega-3, omega-6, and omega-9 fatty acids were formulated into emulsions and were topically applied on rats with excision wounds. All omega-3-, omega-6-, and omega-9-rich oil formulations were found to accelerate wound closure compared to untreated, with significant improvement (p < 0.05) being observed at day 14. EPO induced early deposition of collagen as evaluated by Masson trichrome staining that correlated well with the hydroxyproline content assay, with the highest level at days 3 and 7. Vascular endothelial growth factor (VEGF) showed greater amount of new microvasculature formed in the EPO-treated group, while moderate improvement occurs in the LO and OO groups. EPO increased both the expression of proinflammatory cytokines and growth factors in the early stage of healing and declined at the later stage of healing. LO modulates the proinflammatory cytokines and chemokine but did not affect the growth factors. In contrast, OO induced the expression of growth factors rather than proinflammatory cytokines. These data suggest that LO, EPO, and OO emulsions promote wound healing but they accomplish this by different mechanisms.

Exploratory investigation of the anti-inflammatory effects of RNase A-treated Enterococcus faecalis strain EC-12

We previously reported that the major component of Enterococcus faecalis strain EC-12 (EC-12) inducing production of Interleukin (IL)-12 in mouse/human immune cells was its own RNA. This study aimed to investigate if RNase A-treated EC-12 could also produce IL-10 and to evaluate the possible effects of IL-10 produced by RNase A-treated EC-12. Three experiments were conducted: (1) Assessment of the effect of RNase A-treated EC-12 on transcriptome profiles and biological pathways in human peripheral blood mononuclear cells; (2) Determination of cytokine concentration in its culture supernatants; and (3) Supplementation of RNase A-treated EC-12 (RN) to mice with dextran sodium sulfate-induced colitis. Treatment of EC-12 with RNase A inhibited inflammatory response including the potency to induce IL-12 production, while it did not affect IL-10 production (Experiment 1 and 2). Colitis symptoms were milder in RN than in PBS-supplemented controls (Experiment 3). RNase A-treated EC-12 likely became an anti-inflammatory agent primarily inducing IL-10 production.

Dietary arachidonate in milk replacer triggers dual benefits of PGE2 signaling in LPS-challenged piglet alveolar macrophages

Background

Respiratory infections challenge the swine industry, despite common medicinal practices. The dual signaling nature of PGE₂ (supporting both inflammation and resolution) makes it a potent regulator of immune cell function. Therefore, the use of dietary long chain n-6 PUFA to enhance PGE₂ effects merits investigation.

Methods

Day-old pigs (n = 60) were allotted to one of three dietary groups for 21 d (n = 20/diet), and received either a control diet (CON, arachidonate = 0.5% of total fatty acids), an arachidonate (ARA)-enriched diet (LC n-6, ARA = 2.2%), or an eicosapentaenoic (EPA)-enriched diet (LC n-3, EPA = 3.0%). Alveolar macrophages and lung parenchymal tissue were collected for fatty acid analysis. Isolated alveolar macrophages were stimulated with LPS in situ for 24 h, and mRNA was isolated to assess markers associated with inflammation and eicosanoid production. Culture media were collected to assess PGE₂ secretion. Oxidative burst in macrophages was measured by: 1) oxygen consumption and extracellular acidification (via Seahorse), 2) cytoplasmic oxidation and 3) nitric oxide production following 4, 18, and 24 h of LPS stimulation.

Results

Concentration of ARA (% of fatty acids, w/w) in macrophages from pigs fed LC n-6 was 86% higher than CON and 18% lower in pigs fed LC n-3 (P < 0.01). Following LPS stimulation, abundance of COX-2 and TNF-α mRNA (P <  0.0001), and PGE₂ secretion (P < 0. 01) were higher in LC n-6 PAM vs. CON. However, ALOX5 abundance was 1.6-fold lower than CON. Macrophages from CON and LC n-6 groups were 4-fold higher in ALOX12/15 abundance (P < 0.0001) compared to LC n-3. Oxygen consumption and extracellular acidification rates increased over 4 h following LPS stimulation (P < 0.05) regardless of treatment. Similarly, increases in cytoplasmic oxidation (P < 0.001) and nitric oxide production (P <  0.002) were observed after 18 h of LPS stimulation but were unaffected by diet.

Conclusions

We infer that enriching diets with arachidonic acid may be an effective means to enhance a stronger innate immunologic response to respiratory challenges in neonatal pigs. However, further work is needed to examine long-term safety, clinical efficacy and economic viability.

Electronic supplementary material

The online version of this article (10.1186/s40104-019-0321-1) contains supplementary material, which is available to authorized users.

Prospects on the Use of Schizochytrium sp. to Develop Oral Vaccines

Although oral subunit vaccines are highly relevant in the fight against widespread diseases, their high cost, safety and proper immunogenicity are attributes that have yet to be addressed in many cases and thus these limitations should be considered in the development of new oral vaccines. Prominent examples of new platforms proposed to address these limitations are plant cells and microalgae. Schizochytrium sp. constitutes an attractive expression host for vaccine production because of its high biosynthetic capacity, fast growth in low cost culture media, and the availability of processes for industrial scale production. In addition, whole Schizochytrium sp. cells may serve as delivery vectors; especially for oral vaccines since Schizochytrium sp. is safe for oral consumption, produces immunomodulatory compounds, and may provide bioencapsulation to the antigen, thus increasing its bioavailability. Remarkably, Schizochytrium sp. was recently used for the production of a highly immunoprotective influenza vaccine. Moreover, an efficient method for transient expression of antigens based on viral vectors and Schizochytrium sp. as host has been recently developed. In this review, the potential of Schizochytrium sp. in vaccinology is placed in perspective, with emphasis on its use as an attractive oral vaccination vehicle.

Anti-inflammatory effects of conjugated linoleic acid isomers and essential fatty acids in bovine mammary epithelial cells

Fatty acids are important modulators of inflammatory responses, in particular, n-3 and n-6 essential fatty acids and CLA have received particular attention for their ability to modulate inflammation. The objectives of this study were to compare the effects of CLA and essential fatty acids on the expression of pro and anti- inflammatory cytokines and their protective efficacy against inflammatory status in mammary gland by an in vitro model based on bovine mammary epithelial cells (BME-UV1). Bovine mammary epithelial cells were treated with complete medium containing either 50 µM of cis-9, trans-11 CLA (c9,t11 CLA) or trans-10, cis-12 CLA (t10,c12 CLA) or (α)-linolenic acid (aLnA) or (γ)-linolenic acid (gLnA) or linoleic acid (LA). After 48 h by fatty acids administration the cells were treated for 3 h with 20 µM of lipopolysaccharide (LPS) to induce inflammatory stimulus. Reactive oxygen species (ROS) production after treatments was assessed to verify and to compare the potential protection of different fatty acids against LPS-induced oxidative stress. The messenger RNA abundance of bovine pro and anti-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukine-10 (IL-10)) and peroxisome proliferator receptor-α/γ (PPARγ/α) were determined in BME-UV1 by real-time PCR. The results showed that cells treated with fatty acids and LPS increased ROS production compared with control cells. Among treatments, cells treated with c9,t11 CLA and t10,c12 CLA isomers revealed significant lower levels of ROS production compared with other fatty acids. All fatty acids reduced the gene expression of pro- and anti-inflammatory cytokines. Among fatty acids, t10,c12 CLA, LA and gLnA showed an homogeneous reduction of the three pro-inflammatory cytokines and this may correspond to more balanced and efficient physiological activity and may trigger a better protective effect. The PPARγ gene expression was significantly greater in cells treated with t10,c12 CLA, aLnA and LA, whereas the PPARα gene expression levels were significantly lower in cells treated with all different fatty acids, compared with the control. These results suggest that fatty acids inhibited the transcription of pro-inflammatory cytokines by the upregulation of PPARγ expression.

Membrane Disordering by Eicosapentaenoic Acid in B Lymphomas Is Reduced by Elongation to Docosapentaenoic Acid as Revealed with Solid-State Nuclear Magnetic Resonance Spectroscopy of Model Membranes

BACKGROUND

Plasma membrane organization is a mechanistic target of n-3 (ω-3) polyunsaturated fatty acids. Previous studies show that eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) differentially disrupt plasma membrane molecular order to enhance the frequency and function of B lymphocytes. However, it is not known whether EPA and DHA affect the plasma membrane organization of B lymphomas differently to influence their function.

OBJECTIVE

We tested whether EPA and DHA had different effects on membrane order in B lymphomas and liposomes and studied their effects on B-lymphoma growth.

METHODS

B lymphomas were treated with 25 μmol EPA, DHA, or serum albumin control/L for 24 h. Membrane order was measured with fluorescence polarization, and cellular fatty acids (FAs) were analyzed with GC. Growth was quantified with a viability assay. (2)H nuclear magnetic resonance (NMR) studies were conducted on deuterated phospholipid bilayers.

RESULTS

Treating Raji, Ramos, and RPMI lymphomas for 24 h with 25 μmol EPA or DHA/L lowered plasma membrane order by 10-40% relative to the control. There were no differences between EPA and DHA on membrane order for the 3 cell lines. FA analyses revealed complex changes in response to EPA or DHA treatment and a large fraction of EPA was converted to docosapentaenoic acid (DPA; 22:5n-3). NMR studies, which were used to understand why EPA and DHA had similiar membrane effects, showed that phospholipids containing DPA, similar to DHA, were more ordered than those containing EPA. Finally, treating B lymphomas with 25 μmol EPA or DHA/L did not increase the frequency of B lymphomas compared with controls.

CONCLUSIONS

The results establish that 25 μmol EPA and DHA/L equally disrupt membrane order and do not promote B lymphoma growth. The data open a new area of investigation, which is how EPA's conversion to DPA substantially moderates its influence on membrane properties.

Membrane fatty acid heterogeneity of leukocyte classes is altered during in vitro cultivation but can be restored with ad-hoc lipid supplementation

Background

The cell membrane is a primary and fundamental player in most cellular processes, and fatty acids form a major structural component of cell membranes. The aim of this study was to compare the membrane fatty acid profiles of different human blood leukocytes and selected cell lines, to identify the effects of in vitro culture on fatty acid profiles, and to test medium supplements for their effect on fatty acid profiles.

Methods

Different classes of leukocytes were isolated from human blood and their membrane fatty acid profiles were analysed and compared. After culturing in vitro immortalised and primary leukocytes, membrane fatty acids were analysed and compared. Finally, different lipid formulations were developed and used for supplementing leukocytes in vitro in an effort to maintain the in vivo fatty acid profile. Descriptive and analytical tests were performed to compare the obtained fatty acid profiles.

Results

Membrane fatty acid profiles of primary human CD4⁺ T-lymphocytes, CD8⁺ T-lymphocytes, B-lymphocytes and monocytes differed. Moreover, there were differences among Jurkat, Raji and THP-1 cell lines and the corresponding primary leukocyte classes, as well as between freshly prepared and in vitro cultured primary lymphocytes. A lipid supplement was able to maintain cultured Jurkat cells with a membrane fatty acid profile almost identical to that of the primary CD4⁺ T-lymphocytes. Finally, variations in the lipid supplement composition enabled the development of Jurkat cells with different membrane fatty acid profiles characterising different physiological or pathological human conditions.

Conclusions

Each leukocyte class has its own specific membrane fatty acid profile in vivo. Cultured primary leukocytes and immortalized leukocytic cells display different membrane fatty acid profiles when compared to their respective in vivo counterparts. The membrane fatty acid composition of cultured cells can be restored to reflect that of the corresponding in vivo condition through use of optimised lipid supplementation. Typical physiological or pathological leukocyte membrane fatty acid profiles can be obtained by tuning in vitro fatty acid supplementation.

An Antioxidant Dietary Supplement Improves Brain-Derived Neurotrophic Factor Levels in Serum of Aged Dogs: Preliminary Results

Biological aging is characterized by a progressive accumulation of oxidative damage and decreased endogenous antioxidant defense mechanisms. The production of oxidants by normal metabolism damages proteins, lipids, and nucleotides, which may contribute to cognitive impairment. In this study 36 dogs were randomly divided into four groups and fed croquettes of different compositions for 6 months. We monitored derivatives of reactive oxygen metabolites (dROMs) and biological antioxidant potential (BAP) levels in dogs' plasma samples as well as brain-derived neurotrophic factor (BDNF) serum levels at the beginning and at the end of the dietary regime. Our results showed that a dietary regime, enriched with antioxidants, induced a significant decrease of plasma levels of dROMs (p < 0.005) and a significant increase in BDNF serum levels (p < 0.005) after six months. Thus, we hypothesized a possible role of the diet in modulating pro- and antioxidant species as well as BDNF levels in plasma and serum, respectively. In conclusion the proposed diet enriched with antioxidants might be considered a valid alternative and a valuable strategy to counteract aging-related cognitive decline in elderly dogs.

Comparison of the Effects of Eicosapentaenoic Acid With Docosahexaenoic Acid on the Level of Serum Lipoproteins in Helicobacter pylori: A Randomized Clinical Trial

Background:

Helicobacter pylori infection is the most common chronic bacterial infection around the world and an important cause of gastrointestinal disorders, which might be involved in the pathogenesis of some extragastrointestinal disturbances as well as changes in serum lipid profile. Hypolipemic properties of omega-3 fatty acids have been studied in several studies.

Objectives:

The present study aimed to compare the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on the level of serum lipoproteins in H. pylori.

Patients and Methods:

In a randomized, double-blinded, placebo-controlled clinical trial in Iran, 105 Helicobacter pylori were randomly allocated to receive 2 g of daily EPA (35 patients), DHA (35 patients), or medium-chain triglyceride (MCT) oil as placebo (33 patients) along with conventional tetra-drug H. pylori eradication regimen for 12 weeks.

Results:

From 105 included patients, 97 (31 in EPA, 33 in DHA, and 33 in control groups) completed the study and were included in final analysis. The levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and the ratios of TG/HDL-C, TC/HDL-C, and LDL-C/HDL-C were not significantly different among the three groups, while the level of triglyceride (TG) was statistically different. DHA (-16.6 ± 30.34) and control (+ 15.32 ± 56.47) groups were statistically different with regard to changes in TG levels (P = 0.000).

Conclusions:

There was no difference between the effects of 2 g of EPA or DHA supplementation for 12 weeks on the levels of total cholesterol, LDL-C, HDL-C, TC/HDL-C, TG/HDL-C, and LDL-C/HDL-C; however, it had a desirable effect on the level of TG in a way that the effect of DHA was clearer.

Marine fish oils are not equivalent with respect to B-cell membrane organization and activation

We previously reported that docosahexaenoic-acid (DHA)-enriched fish oil (DFO) feeding altered B-cell membrane organization and enhanced B-cell function. The purpose of this study was to evaluate whether menhaden oil (MO) and eicosapentaenoic-acid (EPA)-enriched fish oil (EFO) alters B-cell function/phenotype similarly. Mice were fed control (CON), MO, EFO or DFO diets for 5weeks. We evaluated the fatty acid composition of B-cell phospholipids, membrane microdomain organization, ex vivo B-cell functionality and in vivo B-cell subsets. Red blood cells and B cells were found to be strongly (r>0.85) and significantly (P<.001) correlated for major n-3 and n-6 long-chain polyunsaturated fatty acids (LCPUFAs). Compared to CON, MO and DFO resulted in decreased clustering of membrane microdomains, whereas EFO increased clustering. All fish oil treatments had 1.12-1.60 times higher CD40 expression following stimulation; however, we observed 0.86 times lower major histocompatibility complex class II expression and 0.7 times lower interleukin (IL)-6 production from EFO, but 3.25 times higher interferon-γ from MO and 1.5 times higher IL-6 from DFO. By 90min of incubation, MO had 1.11 times higher antigen uptake compared to CON, whereas EFO was 0.86 times lower. All fish oil treatments resulted in decreasingly mature splenic and bone marrow B-cell subsets. We conclude that diets high in n-3 LCPUFAs may elicit similar B-cell phenotypes but different organizational and functional outcomes. More specifically, these data suggest that the EPA and DHA content of a diet influences immunological outcomes, highlighting the importance of understanding how specific n-3 LCPUFAs modulate B-cell development and function.

Generation of oxyradicals (O2. and H2O2), mitochondrial activity and induction of apoptosis of PBMC of Cyprinus carpio carpio treated in vivo with halomethanes and with recombinant HSP60 kDa and with LPS of Klebsiella pneumoniae

Halomethanes (HM) can be immunotoxic in mammals; however, in the fish immune system HM effects are unknown. In the current study, we evaluated the mitochondrial activity (MA) by MTT, induction of apoptosis by SubG0 technique and quantified serum ROS concentration (O2. and H2O2) and ROS production in PBMC of Cyprinus carpio carpio treated i.p. with CH2Cl2, CHCl3 and BrCHCl2 (0.004-40.0 mg/kg) for 96 h. Positive controls were recombinant heat shock protein of 60 kDa (rHSP60 kDa) of Klebsiella pneumoniae and its LPS. In addition, for in vitro PBMC cultures, two culture media and two sources of sera were tested. Both positive controls increased the MA more than 4-fold as well as the production of O2. (26-fold) and H2O2 (5-fold) compared to their controls. HM induced different effects on MA, ROS production and an induction of apoptosis, depending on the chlorination patterns and the dose; however, a systemic damage prevails. To fish treated with CH2Cl2, the apoptosis was related with serum ROS concentration and with MA. In contrast, in fish dosed with CHCl3 relationships were not found, deducing a systemic damage. However, in fish treated with BrCHCl2, serum O2. concentration and in vitro ROS generation performed by PBMC were involved in the induction of apoptosis of these cells but not with MA suggesting also immunotoxic effects. The current study demonstrated that HMs are immunomodulators increasing an acute inflammatory response and that rHSP60kDA of K. pneumoniae and its LPS are appropriate antigens to assess the immune response of C. c. carpio.

Dietary omega-3 fatty acids enhance the B1 but not the B2 cell immune response in mice with antigen-induced peritonitis

The effects of omega-3 fatty acids on the adaptive immune response have mainly been analysed in vitro with varying results. How omega-3 fatty acids affect the adaptive immune response in vivo is largely unknown. This study examined the effects of dietary fish oil on the adaptive immune response in antigen-induced inflammation in mice, focusing on its effects on B cells and B cell subsets. Mice were fed a control diet with or without 2.8% fish oil, immunized twice with methylated BSA (mBSA) and peritonitis induced by intraperitoneal injection of mBSA. Serum, spleen and peritoneal exudate were collected prior to and at different time points after induction of peritonitis. Serum levels of mBSA-specific antibodies were determined by ELISA and the number of peritoneal and splenic lymphocytes by flow cytometry. The levels of germinal center B cells and IgM(+), IgG(+) and CD138(+) cells in spleen were evaluated by immunoenzyme staining. Mice fed the fish oil diet had more peritoneal B1 cells, more IgM(+) cells in spleen and higher levels of serum mBSA-specific IgM antibodies compared with that in mice fed the control diet. However, dietary fish oil did not affect the number of peritoneal B2 cells, splenic IgG(+) or CD138(+) cells or serum levels of mBSA-specific IgG antibodies in mice with mBSA-induced peritonitis. These results indicate that dietary fish oil can enhance the adaptive immune response, specifically the B1 cell response, which may lead to better protection against secondary infection as well as improvement in reaching homeostasis following antigenic challenge.

Docosahexaenoic acid reduces inflammation and joint destruction in mice with collagen-induced arthritis

OBJECTIVE

This study was designed to determine the anti-inflammatory activity of docosahexaenoic acid (DHA), alone and in combination with eicosapentaenoic acid (EPA), in a murine model of rheumatoid arthritis, collagen induced arthritis (CIA).

METHODS

The CIA was induced in DBA/1OlaHsd mice by the injection of bovine type II collagen in Freunds's complete adjuvant on days 0 and 21. Mice were fed modified diets containing DHA and/or EPA for 4 weeks prior to the initial collagen injection until study termination at day 45. The severity of CIA was assessed by measuring erythema, edema and mobility of the digits on the fore and hind paws, as well as histology. The level of serum anti-collagen antibodies was determined by ELISA. The ex vivo effects of DHA and/or EPA on splenocyte proliferation and cytokine production were evaluated by BrdU method and ELISA.

RESULTS

Prophylactic treatment with DHA, and not DHA/EPA, significantly reduced arthritis severity and joint damage. Treatment with DHA also decreased anti-collagen (CII) antibodies in vivo, downregulated interleukin-1β, interferonγ and upregulated protective interleukin-10 ex vivo.

CONCLUSION

Prophylactic treatment with DHA was efficacious in a mouse model of rheumatoid arthritis and may be a useful intervention strategy against inflammatory arthritis.

The effect of eicosapentaenoic and docosahexaenoic acid on protein synthesis and breakdown in murine C2C12 myotubes

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been found to stimulate protein synthesis with little information regarding their effects on protein breakdown. Furthermore whether there are distinct effects of EPA and DHA remains to be established. The aim of the current study was to determine the distinct effects of EPA and DHA on protein synthesis, protein breakdown and signalling pathways in C2C12 myotubes. Fully differentiated C2C12 cells were incubated for 24h with 0.1% ethanol (control), 50 μM EPA or 50 μM DHA prior to experimentation. After serum (4h) and amino acid (1h) starvation cells were stimulated with 2 mM L-leucine and protein synthesis measured using (3)H-labelled phenylalanine. Protein breakdown was measured using (3)H-labelled phenylalanine and signalling pathways (Akt, mTOR, p70S6k, 4EBP1, rps6 and FOXO3a) via Western blots. Data revealed that after incubation with EPA protein synthesis was 25% greater (P<0.05) compared to control cells, with no effect of DHA. Protein breakdown was 22% (P<0.05) lower, compared to control cells, after incubation with EPA, with no effect of DHA. Analysis of signalling pathways revealed that both EPA and DHA incubation increased (P<0.05) p70s6k phosphorylation, EPA increased (P<0.05) FOXO3a phosphorylation, with no alteration in other signalling proteins. The current study has demonstrated distinct effects of EPA and DHA on protein metabolism with EPA showing a greater ability to result in skeletal muscle protein accretion.

DHA-enriched fish oil targets B cell lipid microdomains and enhances ex vivo and in vivo B cell function

DHA is a n-3 LCPUFA in fish oil that generally suppresses T lymphocyte function. However, the effect of fish oil on B cell function remains relatively understudied. Given the important role of B cells in gut immunity and increasing human fish oil supplementation, we sought to determine whether DFO leads to enhanced B cell activation in the SMAD-/- colitis-prone mouse model, similar to that observed with C57BL/6 mice. This study tested the hypothesis that DHA from fish oil is incorporated into the B cell membrane to alter lipid microdomain clustering and enhance B cell function. Purified, splenic B cells from DFO-fed mice displayed increased DHA levels and diminished GM1 microdomain clustering. DFO enhanced LPS-induced B cell secretion of IL-6 and TNF-α and increased CD40 expression ex vivo compared with CON. Despite increased MHCII expression in the unstimulated ex vivo B cells from DFO-fed mice, we observed no difference in ex vivo OVA-FITC uptake in B cells from DFO or CON mice. In vivo, DFO increased lymphoid tissue B cell populations and surface markers of activation compared with CON. Finally, we investigated whether these ex vivo and in vivo observations were consistent with systemic changes. Indeed, DFO-fed mice had significantly higher plasma IL-5, IL-13, and IL-9 (Th2-biasing cytokines) and cecal IgA compared with CON. These results support the hypothesis and an emerging concept that fish oil enhances B cell function in vivo.

Effects of DHA-rich n-3 fatty acid supplementation on gene expression in blood mononuclear leukocytes: the OmegAD study

BACKGROUND

Dietary fish oil, rich in n-3 fatty acids (n-3 FAs), e.g. docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), regulate inflammatory reactions by various mechanisms, e.g. gene activation. However, the effects of long-term treatment with DHA and EPA in humans, using genome wide techniques, are poorly described. Hence, our aim was to determine the effects of 6 mo of dietary supplementation with an n-3 FA preparation rich in DHA on global gene expression in peripheral blood mononuclear cells.

METHODS AND FINDINGS

In the present study, blood samples were obtained from a subgroup of 16 patients originating from the randomized double-blind, placebo-controlled OmegAD study, where 174 Alzheimer disease (AD) patients received daily either 1.7 g of DHA and 0.6 g EPA or placebo for 6 months. In blood samples obtained from 11 patients receiving n-3 FA and five placebo, expressions of approximately 8000 genes were assessed by gene array. Significant changes were confirmed by real-time PCR. At 6 months, the n-3 FAs group displayed significant rises of DHA and EPA plasma concentrations, as well as up- and down-regulation of nine and ten genes, respectively, was noticed. Many of these genes are involved in inflammation regulation and neurodegeneration, e.g. CD63, MAN2A1, CASP4, LOC399491, NAIP, and SORL1 and in ubiqutination processes, e.g. ANAPC5 and UBE2V1. Down-regulations of ANAPC5 and RHOB correlated to increases of plasma DHA and EPA levels.

CONCLUSIONS

We suggest that 6 months of dietary n-3 FA supplementation affected expression of genes that might influence inflammatory processes and could be of significance for AD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00211159.

n-3 Polyunsaturated fatty acids exert immunomodulatory effects on lymphocytes by targeting plasma membrane molecular organization

Fish oil, enriched in bioactive n-3 polyunsaturated fatty acids (PUFA), has therapeutic value for the treatment of inflammation-associated disorders. The effects of n-3 PUFAs are pleiotropic and complex; hence, an understanding of their cellular targets and molecular mechanisms of action remains incomplete. Here we focus on recent data indicating n-3 PUFAs exert immunosuppressive effects on the function of effector and regulatory CD4(+) T cells. In addition, we also present emerging evidence that n-3 PUFAs have immunomodulatory effects on B cells. We then focus on one multifaceted mechanism of n-3 PUFAs, which is the alteration of the biophysical and biochemical organization of the plasma membrane. This mechanism is central for downstream signaling, eicosanoid production, transcriptional regulation and cytokine secretion. We highlight recent work demonstrating n-3 PUFA acyl chains in the plasma membrane target the lateral organization of membrane signaling assemblies (i.e. lipid rafts or signaling networks) and de novo phospholipid biosynthesis. We conclude by proposing new functional and mechanistic questions in this area of research that will aid in the development of fish oil as adjuvant therapy for treating unresolved chronic inflammation.

Modulation of blood cell gene expression by DHA supplementation in hypertriglyceridemic men

Our previous study with docosahexaenoic acid (DHA) supplementation to hypertriglyceridemic men showed that DHA reduced several risk factors for cardiovascular disease, including the plasma concentration of inflammatory markers. To determine the effect of DHA supplementation on the global gene expression pattern, we performed Affymetrix GeneChip microarray analysis of blood cells [treated with lipopolysaccharide (LPS) or vehicle] drawn before and after the supplementation of DHA from the hypertriglyceridemic men who participated in that study. Genes that were significantly differentially regulated by the LPS treatment and DHA supplementation were identified. Differential regulation of 18 genes was then verified by quantitative real-time polymerase chain reaction (qRT-PCR). Both microarray and qRT-PCR data showed that DHA supplementation significantly suppressed the expression of low-density lipoprotein (LDL) receptor and cathepsin L1, both of which were also up-regulated by LPS. DHA supplementation also suppressed oxidized LDL (lectin-like) receptor 1 (OLR1). However, LPS did not induce OLR1 mRNA expression. Enrichment with Gene Ontology categories demonstrated that the genes related to transcription factor activity, immunity, host defense and inflammatory responses were inversely regulated by LPS and DHA. These results provide supporting evidence for the anti-inflammatory effects of DHA supplementation, and reveal previously unrecognized genes that are regulated by DHA and are associated with risk factors of cardiovascular diseases.

Membrane raft organization is more sensitive to disruption by (n-3) PUFA than nonraft organization in EL4 and B cells

Model membrane and cellular detergent extraction studies show (n-3) PUFA predominately incorporate into nonrafts; thus, we hypothesized (n-3) PUFA could disrupt nonraft organization. The first objective of this study was to determine whether (n-3) PUFA disrupted nonrafts of EL4 cells, an extension of our previous work in which we discovered an (n-3) PUFA diminished raft clustering. EPA or DHA treatment of EL4 cells increased plasma membrane accumulation of the nonraft probe 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate by ~50-70% relative to a BSA control. Förster resonance energy transfer imaging showed EPA and DHA also disrupted EL4 nanometer scale nonraft organization by increasing the distance between nonraft molecules by ~25% compared with BSA. However, changes in nonrafts were due to an increase in cell size; under conditions where EPA or DHA did not increase cell size, nonraft organization was unaffected. We next translated findings on EL4 cells by testing if (n-3) PUFA administered to mice disrupted nonrafts and rafts. Imaging of B cells isolated from mice fed low- or high-fat (HF) (n-3) PUFA diets showed no change in nonraft organization compared with a control diet (CD). However, confocal microscopy revealed the HF (n-3) PUFA diet disrupted lipid raft clustering and size by ~40% relative to CD. Taken together, our data from 2 different model systems suggest (n-3) PUFA have limited effects on nonrafts. The ex vivo data, which confirm previous studies with EL4 cells, provide evidence that (n-3) PUFA consumed through the diet disrupt B cell lipid raft clustering.

Dietary free oleic and linoleic acid enhances neutrophil function and modulates the inflammatory response in rats

The high ingestion of oleic (OLA) and linoleic (LNA) acids by Western populations, the presence of inflammatory diseases in these populations, and the importance of neutrophils in the inflammatory process led us to investigate the effects of oral ingestion of unesterified OLA and LNA on rat neutrophil function. Pure OLA and LNA were administered by gavage over 10 days. The doses used (0.11, 0.22 and 0.44 g/kg of body weight) were based on the Western consumption of OLA and LNA. Neither fatty acid affected food, calorie or water intake. The fatty acids were not toxic to neutrophils as evaluated by cytometry using propidium iodide (membrane integrity and DNA fragmentation). Neutrophil migration in response to intraperitoneal injection of glycogen and in the air pouch assay, was elevated after administration of either OLA or LNA. This effect was associated with enhancement of rolling and increased release of the chemokine CINC-2alphabeta. Both fatty acids elevated L-selectin expression, whereas no effect on beta(2)-integrin expression was observed, as evaluated by flow cytometry. LNA increased the production of proinflammatory cytokines (IL-1beta and CINC-2alphabeta) by neutrophils after 4 h in culture and both fatty acids decreased the release of the same cytokines after 18 h. In conclusion, OLA and LNA modulate several functions of neutrophils and can influence the inflammatory process.

Comparative effects of DHA and EPA on cell function

Fish oil supplementation has been reported to be generally beneficial in autoimmune, inflammatory and cardiovascular disorders. Most researchers have attributed these beneficial effects to the high content of omega-3 fatty acids in fish oil (FO). The effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are not differentiated in most studies. In fact, up to 1990, purified DHA was not available for human use and there was no study regarding its effects on human immune response. In this review, the differences in the effects of these two fatty acids on cell function are discussed. Studies have shown that EPA and DHA have also different effects on leukocyte functions such as phagocytosis, chemotactic response and cytokine production. DHA and EPA modulate differently expression of genes in lymphocytes. Activation of intracellular signaling pathways involved with lymphocyte proliferation is also differently affected by these two fatty acids. In relation to insulin producing cell line RINm5F, DHA and EPA are cytotoxic at different concentrations and the proteins involved with cell death are differently modulated by these two fatty acids. Substantial improvement in the therapeutic usage of omega-3 fatty acid-rich FO will be possible with the discovery of the different mechanisms of actions of DHA and EPA.

The effect of dietary fish oil-supplementation to healthy young men on oxidative burst measured by whole blood chemiluminescence

Dietary long-chain n-3 PUFA (n-3 LCPUFA) are thought to have immune-modulating effects, but the specific effects and mechanisms are not fully elucidated. The aim of this study was to determine whether dietary n-3 LCPUFA could affect ex vivo oxidative burst in healthy young men. The study had a randomised 2 x 2-factorial design in which subjects were randomly assigned to 8-week supplementation with capsules containing fish oil (about 2.9 g n-3 LCPUFA/d) or olive oil (control). Subjects were also randomly assigned to household use of oils and fat spreads with a high or a low 18:2n-6 content. At baseline and at the end of the intervention, the fatty acid composition of peripheral blood mononuclear cells (PBMC) was analysed by GLC and oxidative burst was studied in whole blood stimulated with zymosan using luminol-enhanced chemiluminescence. The PBMC content of n-3 LCPUFA was markedly increased by the fish oil-supplementation (P < 0.001, compared to the olive oil groups). No effect of the intervention was observed on neutrophil count, but one measure of the zymosan-induced oxidative burst was higher in the fish oil groups (P = 0.03) compared to the olive oil groups. The fat intervention did not in itself affect oxidative burst neither did it change the effect of the fish-oil intervention. The measures of oxidative burst at the end of the intervention period were found to be associated with the DHA content of PBMC (r 0.44, P = 0.016), suggesting a dose-response relationship. These results indicate that n-3 LCPUFA may have immuno-stimulating effects.

Docosahexaenoic acid enhances the toxic effect of imatinib on Bcr-Abl expressing HL-60 cells

The effect of docosahexaenoic acid (DHA) on the killing efficacy of imatinib on HL-60 cells expressing the Bcr-Abl protein was investigated. Imatinib is an Abl tyrosine kinase inhibitor used in the treatment of patients with chronic myeloid leukemia. The pre-treatment with DHA for 24 h raised the effect of imatinib at 100 microM concentration only. On the other hand, after 72 h pre-treatment, all concentrations of DHA tested (25, 50 and 100 microM) enhanced the toxic effect of imatinib. These results indicate that long-term pre-treatment with DHA makes Bcr-Abl HL-60 cells more susceptible to the toxic effect of imatinib.

Effect of a single session of electrical stimulation on activity and expression of citrate synthase and antioxidant enzymes in rat soleus muscle

The aim of our study was to investigate the effect of a single high intensity session of muscle contractions on the activity and expression of citrate synthase (CS) and of the following major antioxidant enzymes: Mn-superoxide dismutase (Mn-SOD), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX). To accomplish this, soleus muscles of male Wistar rats were subjected to contractions using a intense electrical stimulation (ES) protocol. Soleus muscles were isolated either immediately or 1 h after the contractions and utilized for enzyme activity determination, and for analysis of gene expression by quantitative PCR. A significant increase in maximal activity (63%) and expression (80%) of CS was observed in stimulated soleus muscles, isolated 1 h after ES as compared to controls. However, this effect was not observed in muscles isolated immediately after ES. By using macroarray and Real Time RT-PCR analysis, an increase in expression of Mn-SOD, Cu,Zn-SOD, CAT, and GPX was also found. Interestingly, of these enzymes, only CAT activity was significantly increased (44%) 1 h after ES in soleus muscle. These results indicate that acute ES up-regulates activity and expression of CS and CAT in soleus muscles. This increase in expression of CAT may play an important role in counteracting the potential deleterious effects of elevated oxidative stress induced by a high oxidative demand in skeletal muscles subjected to exercise training.

Comparison of biochemical effects of statins and fish oil in brain: the battle of the titans

Neural membranes are composed of glycerophospholipids, sphingolipids, cholesterol and proteins. The distribution of these lipids within the neural membrane is not random but organized. Neural membranes contain lipid rafts or microdomains that are enriched in sphingolipids and cholesterol. These rafts act as platforms for the generation of glycerophospholipid-, sphingolipid-, and cholesterol-derived second messengers, lipid mediators that are necessary for normal cellular function. Glycerophospholipid-derived lipid mediators include eicosanoids, docosanoids, lipoxins, and platelet-activating factor. Sphingolipid-derived lipid mediators include ceramides, ceramide 1-phosphates, and sphingosine 1-phosphate. Cholesterol-derived lipid mediators include 24-hydroxycholesterol, 25-hydroxycholesterol, and 7-ketocholesterol. Abnormal signal transduction processes and enhanced production of lipid mediators cause oxidative stress and inflammation. These processes are closely associated with the pathogenesis of acute neural trauma (stroke, spinal cord injury, and head injury) and neurodegenerative diseases such as Alzheimer disease. Statins, the HMG-CoA reductase inhibitors, are effective lipid lowering agents that significantly reduce risk for cardiovascular and cerebrovascular diseases. Beneficial effects of statins in neurological diseases are due to their anti-excitotoxic, antioxidant, and anti-inflammatory properties. Fish oil omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have similar anti-excitotoxic, antioxidant and anti-inflammatory effects in brain tissue. Thus the lipid mediators, resolvins, protectins, and neuroprotectins, derived from eicosapentaenoic acid and docosahexaenoic acid retard neuroinflammation, oxidative stress, and apoptotic cell death in brain tissue. Like statins, ingredients of fish oil inhibit generation of beta-amyloid and provide protection from oxidative stress and inflammatory processes. Collective evidence suggests that antioxidant, anti-inflammatory, and anti-apoptotic properties of statins and fish oil contribute to the clinical efficacy of treating neurological disorders with statins and fish oil. We speculate that there is an overlap between neurochemical events associated with neural cell injury in stroke and neurodegenerative diseases. This commentary compares the neurochemical effects of statins with those of fish oil.

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.

Mechanisms by which fatty acids regulate leucocyte function

Fatty acids (FAs) have been shown to alter leucocyte function and thus to modulate inflammatory and immune responses. In this review, the effects of FAs on several aspects of lymphocyte, neutrophil and macrophage function are discussed. The mechanisms by which FAs modulate the production of lipid mediators, activity of intracellular signalling pathways, activity of lipid-raft-associated proteins, binding to TLRs (Toll-like receptors), control of gene expression, activation of transcription factors, induction of cell death and production of reactive oxygen and nitrogen species are described in this review. The rationale for the use of specific FAs to treat patients with impaired immune function is explained. Substantial improvement in the therapeutic usage of FAs or FA derivatives may be possible based on an improvement in the understanding of the precise molecular mechanisms of action with respect to the different leucocyte types and outcome with respect to the inflammatory responses.

Modulation of inflammation in brain: a matter of fat

Neuroinflammation is a host defense mechanism associated with neutralization of an insult and restoration of normal structure and function of brain. Neuroinflammation is a hallmark of all major CNS diseases. The main mediators of neuroinflammation are microglial cells. These cells are activated during a CNS injury. Microglial cells initiate a rapid response that involves cell migration, proliferation, release of cytokines/chemokines and trophic and/or toxic effects. Cytokines/chemokines stimulate phospholipases A2 and cyclooxygenases. This results in breakdown of membrane glycerophospholipids with the release of arachidonic acid (AA) and docosahexaenoic acid (DHA). Oxidation of AA produces pro-inflammatory prostaglandins, leukotrienes, and thromboxanes. One of the lyso-glycerophospholipids, the other products of reactions catalyzed by phospholipase A2, is used for the synthesis of pro-inflammatory platelet-activating factor. These pro-inflammatory mediators intensify neuroinflammation. Lipoxin, an oxidized product of AA through 5-lipoxygenase, is involved in the resolution of inflammation and is anti-inflammatory. Docosahexaenoic acid is metabolized to resolvins and neuroprotectins. These lipid mediators inhibit the generation of prostaglandins, leukotrienes, and thromboxanes. Levels of prostaglandins, leukotrienes, and thromboxanes are markedly increased in acute neural trauma and neurodegenerative diseases. Docosahexaenoic acid and its lipid mediators prevent neuroinflammation by inhibiting transcription factor NFkappaB, preventing cytokine secretion, blocking the synthesis of prostaglandins, leukotrienes, and thromboxanes, and modulating leukocyte trafficking. Depending on its timing and magnitude in brain tissue, inflammation serves multiple purposes. It is involved in the protection of uninjured neurons and removal of degenerating neuronal debris and also in assisting repair and recovery processes. The dietary ratio of AA to DHA may affect neurodegeneration associated with acute neural trauma and neurodegenerative diseases. The dietary intake of docosahexaenoic acid offers the possibility of counter-balancing the harmful effects of high levels of AA-derived pro-inflammatory lipid mediators.

Effect of docosahexaenoic acid-rich fish oil supplementation on human leukocyte function

BACKGROUND

The effect of a docosahexaenoic acid (DHA)-rich fish oil (FO) supplementation on human leukocyte function was investigated.

METHODS

Ten male volunteers were supplemented with 3g/day FO containing 26% eicosapentaenoic acid (EPA, 20:5, n-3) and 54% DHA (22:6, n-3) for 2 months.

RESULTS

FO supplementation changed the fatty acid (FA) composition of leukocytes resulting in an increase of n-3/n-6 ratio from 0.18 to 0.62 in lymphocytes and from 0.15 to 0.70 in neutrophils. DHA-rich FO stimulated an increase in phagocytic activity by 62% and 145% in neutrophils and monocytes, respectively. Neutrophil chemotactic response was increased by 128%. The rate of production of reactive oxygen species by neutrophils was also increased, as it was with lymphocyte proliferation. These changes were partially reversed after a 2-month wash out period. With respect to cytokine production by lymphocytes, interleukin (IL)-4 release was not altered, whereas secretions of IL-10, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha were raised. These results are in contrast to those described by others using EPA-rich FO supplementation. Lymphocyte pleiotropic gene expression was analyzed by a macroarray technique. Of the analyzed genes (588 in total), 77 were modified by the supplementation. FO supplementation resulted in up-regulation of 6 genes (GATA binding protein 2, IL-6 signal transducer, transforming growth factor alpha, TNF, heat shock 90kDa protein 1-alpha and heat shock protein 70kDa 1A) and a down regulation of 71 genes (92.2% of total genes changed). The largest functional group of altered genes was that related to signaling pathways (22% of the total modified genes).

CONCLUSIONS

Therefore, although EPA and DHA are members of n-3 FA family, changes in the proportion of DHA and EPA exert different effects on neutrophil, monocyte and lymphocyte function, which may be a result of specific changes in gene expression.