Effect of dihomogammalinolenic acid and its 15-lipoxygenase metabolite on eicosanoid metabolism by human mononuclear leukocytes in vitro: selective inhibition of the 5-lipoxygenase pathway

Buyang Huanwu Decoction Alleviates Atherosclerosis by Regulating gut Microbiome and Metabolites in Apolipoprotein E-deficient Mice fed with High-fat Diet

ABSTRACT

The traditional Chinese herbal prescription Buyang Huanwu decoction (BHD), effectively treats atherosclerosis. However, the mechanism of BHD in atherosclerosis remains unclear. We aimed to determine whether BHD could alleviate atherosclerosis by altering the microbiome-associated metabolic changes in atherosclerotic mice. An atherosclerotic model was established in apolipoprotein E-deficient mice fed high-fat diet, and BHD was administered through gavage for 12 weeks at 8.4 g/kg/d and 16.8 g/kg/d. The atherosclerotic plaque size, composition, serum lipid profile, and inflammatory cytokines, were assessed. Mechanistically, metabolomic and microbiota profiles were analyzed by liquid chromatography-mass spectrometry and 16S rRNA gene sequencing, respectively. Furthermore, intestinal microbiota and atherosclerosis-related metabolic parameters were correlated using Spearman analysis. Atherosclerotic mice treated with BHD exhibited reduced plaque area, aortic lumen occlusion, and lipid accumulation in the aortic root. Nine perturbed serum metabolites were significantly restored along with the relative abundance of microbiota at the family and genus levels but not at the phylum level. Gut microbiome improvement was strongly negatively correlated with improved metabolite levels. BHD treatment effectively slows the progression of atherosclerosis by regulating altered intestinal microbiota and perturbed metabolites.

Supplementation of Dihomo-γ-Linolenic Acid for Pollen-Induced Allergic Symptoms in Healthy Subjects: A Randomized, Double-Blinded, Placebo-Controlled Trial

Dihomo-γ-linolenic acid (DGLA) is an n-6 polyunsaturated fatty acid that has been shown to have anti-inflammatory and anti-allergic effects in mice and cell study. To date, however, no human intervention study has examined the effects of DGLA. Therefore, we investigated the effects of DGLA on pollen-induced allergic symptoms in healthy adults. We performed a randomized, double-blind, placebo-controlled, parallel-group study comprising healthy Japanese men and women. Each subject received four 250 mg capsules providing 314 mg DGLA/day (DGLA group, n = 18) or olive oil (placebo group, n = 15) for 15 weeks. The primary outcomes, classification of the severity of allergic rhinitis symptoms (CSARS), and the Japanese Rhino-conjunctivitis Quality of Life Questionnaire (JRQLQ) served as symptom scores during the pollen season. In the DGLA group, the cedar pollen associated symptoms of sneezing and a blocked nose in the CSARS were significantly lower than those in the placebo group (p < 0.05, p < 0.01, respectively). Significant trends were observed the symptoms of runny nose in the CSARS and total symptom score (TSS) in the JRQLQ for cedar pollen (p < 0.1). To our knowledge, this is the first study to report the effects of DGLA in humans, and the results suggest that DGLA is effective in reducing allergic symptoms caused by pollen.

Elevated phospholipid hydroperoxide glutathione peroxidase (GPX4) expression modulates oxylipin formation and inhibits age-related skeletal muscle atrophy and weakness

Our previous studies support a key role for mitochondrial lipid hydroperoxides as important contributors to denervation-related muscle atrophy, including muscle atrophy associated with aging. Phospholipid hydroperoxide glutathione peroxidase 4 (GPX4) is an essential antioxidant enzyme that directly reduces phospholipid hydroperoxides and we previously reported that denervation-induced muscle atrophy is blunted in a mouse model of GPX4 overexpression. Therefore, the goal of the present study was to determine whether GPX4 overexpression can reduce the age-related increase in mitochondrial hydroperoxides in skeletal muscle and ameliorate age-related muscle atrophy and weakness (sarcopenia). Male C57Bl6 WT and GPX4 transgenic (GPX4Tg) mice were studied at 3 to 5 and 23-29 months of age. Basal mitochondrial peroxide generation was reduced by 34% in muscle fibers from aged GPX4Tg compared to old WT mice. GPX4 overexpression also reduced levels of lipid peroxidation products: 4-HNE, MDA, and LOOHs by 38%, 32%, and 84% respectively in aged GPX4Tg mice compared to aged WT mice. Muscle mass was preserved in old GPX4 Tg mice by 11% and specific force generation was 21% higher in old GPX4Tg versus age matched male WT mice. Oxylipins from lipoxygenases (LOX) and cyclooxygenase (COX), as well as less abundant non-enzymatically generated isomers, were significantly reduced by GPX4 overexpression. The expression of cPLA2, 12/15-LOX and COX-2 were 1.9-, 10.5- and 3.4-fold greater in old versus young WT muscle respectively, and 12/15-LOX and COX-2 levels were reduced by 37% and 35%, respectively in muscle from old GPX4Tg mice. Our study suggests that lipid peroxidation products may play an important role in the development of sarcopenia, and their detoxification might be an effective intervention in preventing muscle atrophy.

Relationships between plasma fatty acids in adults with mild, moderate, or severe COVID-19 and the development of post-acute sequelae

Background

SARS-CoV-2 has infected millions across the globe. Many individuals are left with persistent symptoms, termed post-acute sequelae of COVID-19 (PASC), for months after infection. Hyperinflammation in the acute and convalescent stages has emerged as a risk factor for poor disease outcomes, and this may be exacerbated by dietary inadequacies. Specifically, fatty acids are powerful inflammatory mediators and may have a significant role in COVID-19 disease modulation.

Objective

The major objective of this project was to pilot an investigation of plasma fatty acid (PFA) levels in adults with COVID-19 and to evaluate associations with disease severity and PASC.

Methods and procedures

Plasma from adults with (N = 41) and without (N = 9) COVID-19 was analyzed by gas chromatography-mass spectrometry (GC-MS) to assess differences between the concentrations of 18 PFA during acute infection (≤14 days post-PCR + diagnosis) in adults with varying disease severity. Participants were grouped based on mild, moderate, and severe disease, alongside the presence of PASC, a condition identified in patients who were followed beyond acute-stage infection (N = 23).

Results

Significant differences in PFA profiles were observed between individuals who experienced moderate or severe disease compared to those with mild infection or no history of infection. Palmitic acid, a saturated fat, was elevated in adults with severe disease (p = 0.04), while behenic (p = 0.03) and lignoceric acid (p = 0.009) were lower in adults with moderate disease. Lower levels of the unsaturated fatty acids, γ-linolenic acid (GLA) (p = 0.03), linoleic (p = 0.03), and eicosapentaenoic acid (EPA) (p = 0.007), were observed in adults with moderate disease. Oleic acid distinguished adults with moderate disease from severe disease (p = 0.04), and this difference was independent of BMI. Early recovery-stage depletion of GLA (p = 0.02) and EPA (p = 0.0003) was associated with the development of PASC.

Conclusion

Pilot findings from this study support the significance of PFA profile alterations during COVID-19 infection and are molecular targets for follow-up attention in larger cohorts. Fatty acids are practical, affordable nutritional targets and may be beneficial for modifying the course of disease after a COVID-19 diagnosis. Moreover, these findings can be particularly important for overweight and obese adults with altered PFA profiles and at higher risk for PASC.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT04603677].

Anti-Inflammatory and Proresolving Effects of the Omega-6 Polyunsaturated Fatty Acid Adrenic Acid

Polyunsaturated fatty acids (PUFAs) and their metabolites are potent regulators of inflammation. Generally, omega (n)-3 PUFAs are considered proresolving whereas n-6 PUFAs are classified as proinflammatory. In this study, we characterized the inflammatory response in murine peritonitis and unexpectedly found the accumulation of adrenic acid (AdA), a poorly studied n-6 PUFA. Functional studies revealed that AdA potently inhibited the formation of the chemoattractant leukotriene B₄ (LTB₄), specifically in human neutrophils, and this correlated with a reduction of its precursor arachidonic acid (AA) in free form. AdA exposure in human monocyte-derived macrophages enhanced efferocytosis of apoptotic human neutrophils. In vivo, AdA treatment significantly alleviated arthritis in an LTB₄-dependent murine arthritis model. Our findings are, to our knowledge, the first to indicate that the n-6 fatty acid AdA effectively blocks production of LTB₄ by neutrophils and could play a role in resolution of inflammation in vivo.

Prospective clinical trial examining the impact of genetic variation in FADS1 on the metabolism of linoleic acid- and ɣ-linolenic acid-containing botanical oils

BACKGROUND

Unexplained heterogeneity in clinical trials has resulted in questions regarding the effectiveness of ɣ-linolenic acid (GLA)-containing botanical oil supplements. This heterogeneity may be explained by genetic variation within the fatty acid desaturase (FADS) gene cluster that is associated with circulating and tissue concentrations of arachidonic acid (ARA) and dihomo-ɣ-linolenic acid (DGLA), both of which may be synthesized from GLA and result in proinflammatory and anti-inflammatory metabolites, respectively.

OBJECTIVES

The objective of this study was to prospectively compare the capacity of a non-Hispanic white cohort, stratified by FADS genotype at the key single-nucleotide polymorphism (SNP) rs174537, to metabolize 18-carbon omega-6 (n-6) PUFAs in borage oil (BO) and soybean oil (SO) to GLA, DGLA, and ARA.

METHODS

Healthy adults (n = 64) participated in a randomized, double-blind, crossover intervention. Individuals received encapsulated BO (Borago officinalis L.; 37% LA and 23% GLA) or SO [Glycine max (L.) Merr.; 50% LA and 0% GLA] for 4 wk, followed by an 8-wk washout period, before consuming the opposite oil for 4 wk. Serum lipids and markers of inflammation (C-reactive protein) were assessed for both oil types at baseline and during weeks 2 and 4 of the intervention.

RESULTS

SO supplementation failed to alter circulating concentrations of any n-6 long-chain PUFAs. In contrast, a modest daily dose of BO elevated serum concentrations of GLA and DGLA in an rs174537 genotype-dependent manner. In particular, DGLA increased by 57% (95% CI: 0.38, 0.79) in GG genotype individuals, but by 141% (95% CI: 1.03, 2.85) in TT individuals. For ARA, baseline concentrations varied substantially by genotype and increased modestly with BO supplementation, suggesting a key role for FADS variation in the balance of DGLA and ARA.

CONCLUSIONS

The results of this study clearly suggest that personalized and population-based approaches considering FADS genetic variation may be necessary to optimize the design of future clinical studies with GLA-containing oils. This trial was registered at clinicaltrials.gov as NCT02337231.

Associations between omega-6 polyunsaturated fatty acids, hyperinsulinemia and incident diabetes by race/ethnicity: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND & AIMS

Omega-6 polyunsaturated fatty acids (PUFAs) have been shown to relate to insulin resistance and type 2 diabetes (T2D), but influence of race/ethnicity has not been investigated. The aim of this study was to determine whether omega-6 PUFAs, and estimated desaturase enzyme activity, are associated with fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and incident T2D, and whether associations differ by race/ethnicity.

METHODS

This study was conducted in the Multi-Ethnic Study of Atherosclerosis (MESA) (N = 6282). Associations between baseline plasma phospholipid fatty acids (LA, Linoleic Acid; GLA, γ-linoleic acid; DGLA, Dihomo-γ-linolenic acid; AA, arachidonic acid; D5D, delta-5 desaturase; D6D, delta-6 desaturase), fasting glucose, insulin, and HOMA-IR [(fasting insulin - fasting glucose)/22.5] were evaluated using linear regression. Associations between omega-6 PUFAs (N = 5508 after excluding diabetics at baseline) and T2D incidence were assessed using Cox proportional hazards regression. Analyses were replicated/stratified by race/ethnicity (White, Black, Chinese, Hispanic) and tests for interaction were assessed by inclusion of a cross-product term in models.

RESULTS

In fully adjusted models, insulin and HOMA-IR were positively associated with LA (insulin: 0.213 per SD, p = 0.01; HOMA-IR: 0.252 per SD, p < 0.001), GLA (insulin: 0.010 per SD, p < 0.001; HOMA-IR: 0.006 per SD, p < 0.001), DGLA (insulin: 0.279 per SD, p < 0.001; HOMA-IR: 0.175 per SD, p < 0.001) and D6D activity (insulin: 0.001 per SD, p < 0.001; HOMA-IR: 0.006 per SD, p < 0.001), and inversely associated with AA (insulin -0.272 per SD, p < 0.001; HOMA-IR: -0.125 per SD, p = 0.03) and D5D activity (insulin: -0.530 per SD, p < 0.001; HOMA-IR: -0.322 per SD, p < 0.001), while weak or no associations were observed with fasting glucose, and associations appeared to differ by race/ethnicity. After accounting for HOMA-IR at baseline, LA was inversely (HR: 0.87, p = 0.003) and DGLA (HR: 1.17, p < 0.001) and AA (HR: 1.15, p = 0.001) were positively associated with T2D in the overall population, but associations were attenuated or no longer present when stratified by race/ethnicity (P-interaction >0.05).

CONCLUSIONS

Results confirm previous reports that omega-6 PUFAs are associated with hyperinsulinemia. Findings suggest omega-6 PUFAs are more likely markers of hyperinsulinemia rather than a protective/risk factor for T2D and indicate racial/ethnic differences in associations, but further research is needed to confirm findings.

Dihomo-γ-linolenic acid inhibits several key cellular processes associated with atherosclerosis

Atherosclerosis and its complications are responsible for one in three global deaths. Nutraceuticals show promise in the prevention and treatment of atherosclerosis but require an indepth understanding of the mechanisms underlying their actions. A previous study showed that the omega-6 fatty acid, dihomo-γ-linolenic acid (DGLA), attenuated atherosclerosis in the apolipoprotein E deficient mouse model system. However, the mechanisms underlying such protective effects of DGLA are poorly understood and were therefore investigated. We show that DGLA attenuates chemokine-driven monocytic migration together with foam cell formation and the expression of key pro-atherogenic genes induced by three pro-inflammatory cytokines in human macrophages. The effect of DGLA on interferon-γ signaling was mediated via inhibition of signal transducer and activator of transcription-1 phosphorylation on serine 727. In relation to anti-foam cell action, DGLA inhibits modified LDL uptake by both macropinocytosis and receptor-mediated endocytosis, the latter by reduction in expression of two key scavenger receptors (SR-A and CD36), and stimulates cholesterol efflux from foam cells. DGLA also improves macrophage mitochondrial bioenergetic profile by decreasing proton leak. Gamma-linolenic acid and prostaglandin E1, upstream precursor and key metabolite respectively of DGLA, also acted in an anti-atherogenic manner. The actions of DGLA extended to other key atherosclerosis-associated cell types with attenuation of endothelial cell proliferation and migration of smooth muscle cells in response to platelet-derived growth factor. This study provides novel insights into the molecular mechanisms underlying the anti-atherogenic actions of DGLA and supports further assessments on its protective effects on plaque regression in vivo and in human trials.

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Dihomo-γ-linolenic acid (DGLA) attenuates atherosclerosis in a mouse model system.

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The mechanisms underlying anti-atherogenic actions of DGLA are poorly understood.

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DGLA inhibited atherogenic processes in three key cell types in this disease.

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Mechanisms underlying such protective actions of DGLA were identified.

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Studies inform on the beneficial anti-atherogenic actions of DGLA.

A specific combined long-chain polyunsaturated fatty acid supplementation reverses fatty acid profile alterations in a mouse model of chronic asthma

Background

The immune-modulating potential of long-chain polyunsaturated fatty acids (LCPUFAs) based on their conversion into lipid mediators in inflammatory situations has been proven by several studies. Respecting the immune-modulative role of lipid mediators in bronchoconstriction, airway inflammation and resolution of inflammatory processes, LCPUFAs play an important role in asthma. To design a disease-specific and most beneficial LCPUFA supplementation strategy, it is essential to understand how asthma alters LCPUFA profiles. Therefore, this study characterizes the alterations of LCPUFA profiles induced by allergic asthma. In addition, this study explores whether a simple eicosapentaenoic acid (EPA) alone or a specific combined LCPUFA supplementation could restore imbalanced LCPUFA profiles.

Methods

Mice were sensitized with a daily dose of 40 μg house dust mite (HDM)-extract in a recall model and fed with either normal diet, EPA or a specific combined (sc)-LCPUFA supplementation containing EPA, docosahexaenoic acid (DHA), γ -linolenic acid (GLA) and stearidonic acid (SDA) for 24 days. After recall with HDM, mice were sacrificed and blood and lung tissue were collected. Fatty acid profiles were determined in plasma, blood cells and lung cells of asthmatic mice by capillary gas-chromatography.

Results

In lung cells of asthmatic mice, arachidonic acid (AA, p < 0.001) and DHA (p < 0.01) were increased while dihomo-γ-linolenic acid (DGLA, p < 0.05) was decreased. EPA supplementation increased only EPA (p < 0.001) and docosapentaenoic acid (DPA, p < 0.001), but neither DGLA nor DHA in lung cells of asthmatic mice. In contrast, a specific combined dietary supplementation containing n-3 and n-6 LCPUFAs could decrease AA (p < 0.001), increase EPA (p < 0.001), DPA (p < 0.001) and DHA (p < 0.01) and could reverse the lack of DGLA (p < 0.05).

Conclusions

In summary, allergic asthma alters LCPUFA profiles in blood and lung tissue. In contrast to the EPA supplementation, the distinct combination of n-3 and n-6 LCPUFAs restored the LCPUFA profiles in lung tissue of asthmatic mice completely. Subsequently, sc-LCPUFA supplementation is likely to be highly supportive in limiting and resolving the inflammatory process in asthma.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0947-6) contains supplementary material, which is available to authorized users.

Chemical Analysis of Astragali Complanati Semen and Its Hypocholesterolemic Effect Using Serum Metabolomics Based on Gas Chromatography-Mass Spectrometry

The hypocholesterolemic protective effect of the dried seed of Astragalus complanatus (ACS) was investigated in rats fed with normal diet, high cholesterol diet (HCD), and HCD plus 70% ethanol extract of ACS (600 mg/kg/day) by oral gavage for four weeks. ACS extract was tested to be rich in antioxidants, which may be contributed to its high content of phenolic compounds. Consumption of ACS remarkably suppressed the elevated total cholesterol (p < 0.01) and LDL-C (p < 0.001) induced by HCD. Chemical constituents of ACS extract were analyzed by ultra-performance liquid chromatography coupled with electrospray ionization orbitrap mass spectrometry and the results showed that the ACS extract mainly consisted of phenolic compounds including flavonoids and flavonoid glycosides. In addition, based on the serum fatty acid profiles, elucidated using gas chromatography-mass spectrometry, free and esterified fatty acids including docosapentaenoic acid, adrenic acid, dihomo-γ-linolenic acid and arachidonic acid were regulated in ACS treatment group. Western blot results further indicated the protein expression of peroxisome proliferator-activated receptor alpha (PPARα) (p < 0.05) in liver was upregulated in ACS treatment group. To conclude, our results clearly demonstrated that ACS provides beneficial effect on lowering HCD associated detrimental change.

Sesamin attenuates allergic airway inflammation through the suppression of nuclear factor-kappa B activation

The aim of the present study is to determine the role of sesamin, the most abundant lignan in sesame seed oil, on the regulation of allergic airway inflammation in a murine asthma model. A BALB/c mouse model with allergic asthma was used to evaluate the effects of sesamin on nuclear factor-kappa B (NF-κB) activation. An enzyme-linked immunosorbent assay was used to determine protein expression in bronchoalveolar lavage (BAL) fluids. Hematoxylin and eosin staining was performed to examine histological changes. Moreover, western blot analysis was used to detect the expression of proteins in tissues. Prior to administering sesamin, the mice developed the following pathophysiological features of asthma: An increase in the number of inflammatory cells, increased levels of interleukin (IL)-4, IL-5 and IL-13, decreased levels of interferon-γ in BAL fluids and lung tissues, increased immunoglobulin E (IgE) levels in the serum and an increased activation of NF-κB in lung tissues. Following treatment with sesamin, the mice had evidently reduced peribronchiolar inflammation and airway inflammatory cell recruitment, inhibited production of several cytokines in BAL fluids and lung tissues, and decreased IgE levels. Following inhalation of ovalbumin, the administration of sesamin also inhibited the activation of NF-κB. In addition, sesamin administration reduced the phosphorylation of p38 mitogen-activated protein kinases (MAPKs). The present study demonstrates that sesamin decreases the activation of NF-κB in order to attenuate allergic airway inflammation in a murine model of asthma, possibly via the regulation of phosphorylation of p38 MAPK. These observations provide an important molecular mechanism for the potential use of sesamin in preventing and/or treating asthma, as well as other airway inflammatory disorders.

Gamma-linolenic acid, Dihommo-gamma linolenic, Eicosanoids and Inflammatory Processes

Gamma-linolenic acid (GLA, 18:3n-6) is an omega-6 (n-6), 18 carbon (18C-) polyunsaturated fatty acid (PUFA) found in human milk and several botanical seed oils and is typically consumed as part of a dietary supplement. While there have been numerous in vitro and in vivo animal models which illustrate that GLA-supplemented diets attenuate inflammatory responses, clinical studies utilizing GLA or GLA in combination with omega-3 (n-3) PUFAs have been much less conclusive. A central premise of this review is that there are critical metabolic and genetic factors that affect the conversion of GLA to dihommo-gamma linolenic acid (DGLA, 20:3n-6) and arachidonic acid (AA, 20:4n-6), which consequently affects the balance of DGLA- and AA- derived metabolites. As a result, these factors impact the clinical effectiveness of GLA or GLA/(n-3) PUFA supplementations in treating inflammatory conditions. Specifically, these factors include: 1) the capacity for different human cells and tissues to convert GLA to DGLA and AA and to metabolize DGLA and AA to bioactive metabolites; 2) the opposing effects of DGLA and AA metabolites on inflammatory processes and diseases; and 3) the impact of genetic variations within the fatty acid desaturase (FADS) gene cluster, in particular, on AA/DGLA ratios and bioactive metabolites. We postulate that these factors influence the heterogeneity of results observed in GLA supplement-based clinical trials and suggest that "one-size fits all" approaches utilizing PUFA-based supplements may no longer be appropriate for the prevention and treatment of complex human diseases.

Combinations of distinct long-chain polyunsaturated fatty acid species for improved dietary treatment against allergic bronchial asthma

Allergic bronchial asthma is a chronic inflammatory disease of the airways with an increasing incidence in Western societies. Exposure to allergens provokes recurrent attacks of breathlessness, airway hyperreactivity, wheezing, and coughing. For the early phase and milder forms of allergic asthma, dietary supplementation with long-chain polyunsaturated fatty acids (LCPUFA), predominantly fish oil-associated eicosapentaenoic (C20:5 ω-3) and docosahexaenoic acid (C22:6 ω-3), and distinct crop oil-derived fatty acids might provide a sustainable treatment strategy, as discussed in several studies. In addition to immune-controlling prostaglandins, leukotrienes, and thromboxanes, specialized proresolving mediators, such as lipoxins, resolvins, protectins, and maresins, are metabolized from different LCPUFA, which actively resolve inflammation. The aim of this review was to discuss the possible synergistic effects of ω-3 and ω-6 LCPUFA combinations concerning rebuilding fatty acid homeostasis in cellular membranes, modifying eicosanoid metabolic pathways, controlling inflammatory processes by focusing on resolving inflammation in the bronchoalveolar system on the cellular level, and helping to control clinical symptoms in bronchial asthma.

Impact of botanical oils on polyunsaturated fatty acid metabolism and leukotriene generation in mild asthmatics

Background

Dietary supplementation with botanical oils that contain n-6 and n-3 eighteen carbon chain (18C)-PUFA such as γ linolenic acid (GLA, 18:3n-6), stearidonic acid (SDA, 18:4n-3) and α linolenic acid (ALA, 18:3n-3) have been shown to impact PUFA metabolism, alter inflammatory processes including arachidonic acid (AA) metabolism and improve inflammatory disorders.

Methods

The diet of mild asthmatics patients was supplemented for three weeks with varying doses of two botanical seed oils (borage oil [Borago officinalis, BO] and echium seed oil [Echium plantagineum; EO]) that contain SDA, ALA and GLA. A three week wash out period followed. The impact of these dietary manipulations was evaluated for several biochemical endpoints, including in vivo PUFA metabolism and ex vivo leukotriene generation from stimulated leukocytes.

Results

Supplementation with several EO/BO combinations increased circulating 20–22 carbon (20–22C) PUFAs, including eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and dihommo-gammalinolenic acid (DGLA), which have been shown to inhibit AA metabolism and inflammation without impacting circulating AA levels. BO/EO combinations also inhibited ex vivo leukotriene generation with some combinations attenuating cysteinyl leukotriene generation in stimulated basophils by >50% and in stimulated neutrophils by >35%.

Conclusions

This study shows that dietary supplementation with BO/EO alters 20–22C PUFA levels and attenuates leukotriene production in a manner consistent with a reduction in inflammation.

Chondroprotective and anti-inflammatory effects of sesamin

Osteoarthritis (OA) is a major disability of elderly people. Sesamin is the main compound in Sesamun indicum Linn., and it has an anti-inflammatory effect by specifically inhibiting Δ5-desaturase in polyunsaturated fatty acid biosynthesis. The chondroprotective effects of sesamin were thus studied in a porcine cartilage explant induced with interleukin-1beta (IL-1β) and in a papain-induced osteoarthritis rat model. With the porcine cartilage explant, IL-1β induced release of sulfated-glycosaminoglycan (s-GAG) and hydroxyproline release, and this induction was significantly inhibited by sesamin. This ability to inhibit these processes might be due to its ability to decrease expression of MMP-1, -3 and -13, which can degrade both PGs and type II collagen, both at the mRNA and protein levels. Interestingly, activation of MMP-3 might also be inhibited by sesamin. Moreover, in human articular chondrocytes (HACs), some pathways of IL-1β signal transduction were inhibited by sesamin: p38 and JNK. In the papain-induced OA rat model, sesamin treatment reversed the following pathological changes in OA cartilage: reduced disorganization of chondrocytes in cartilage, increased cartilage thickness, and decreased type II collagen and PGs loss. Sesamin alone might increase formation of type II collagen and PGs in the cartilage tissue of control rats. These results demonstrate that sesamin efficiently suppressed the pathological processes in an OA model. Thus, sesamin could be a potential therapeutic strategy for treatment of OA.

Oral supplementation with dihomo-γ-linolenic acid (DGLA)-enriched oil increases serum DGLA content in healthy adults

Dihomo-γ-linolenic acid (DGLA) is one of the polyunsaturated fatty acids, and is expected to show anti-allergic activity. We examined the effects of supplementation with DGLA-enriched oil (450 mg as free DGLA) for 4 weeks in healthy adults in a randomized controlled study. The DGLA composition in the total fatty acids of serum phospholipids increased from 2.0 to 3.4%, and returned to the initial level after a 4-week washout. No side effects or changes in blood biochemical parameters were observed. These results indicate that serum DGLA content can be safely increased by supplementation with 450 mg DGLA under these conditions.

Obesity modifies the association between plasma phospholipid polyunsaturated fatty acids and markers of inflammation: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND OBJECTIVE

Systemic inflammation is a well-known risk factor for diseases such as atherosclerosis and is augmented by the presence of obesity. In addition, it has been shown that inflammation may be negatively influenced by certain macronutrients, specifically the omega-3 and omega-6 fatty acids. The primary aim of this study is to determine whether obesity modifies the association between plasma phospholipid polyunsaturated fatty acids (PUFAs) and markers of inflammation and endothelial activation in Multi-Ethnic Study of Atherosclerosis (MESA) participants.

SUBJECTS

A sample of 2848 adults (25% African American, Chinese, Hispanic, and White) randomly selected from the MESA cohort.

MEASUREMENTS

Relative plasma PUFA concentrations were determined using gas chromatography-flame ionization detection. Levels of three inflammatory markers (high-sensitivity C-reactive protein, interleukin (IL)-6 and tumor necrosis factor-receptor 1) and two endothelial activation markers (soluble intercellular adhesion molecule-1 (sICAM-1) and E-selectin) were determined with enzyme immunoassays. Linear regression analysis was used to evaluate the relationship between these markers and plasma PUFAs.

RESULTS

Obesity modified the associations of linoleic acid (P(int)=0.01), dihomo-γ-linolenic (P(int)=0.07) and eicosapentaenoic acid (EPA) (P(int)=0.04) with sICAM-1 concentrations; in addition, obesity modified the association of IL-6 with dihomo-γ-linolenic (P(int)=0.01). In obese individuals, sICAM-1 was inversely related to EPA levels (P=0.02), but directly related to linoleic acid levels (P<0.001). Conversely, sICAM-1 was inversely related to linoleic acid levels in normal weight individuals (P=0.04). IL-6 concentrations were significantly and directly related to dihomo-γ-linolenic acid (DGLA) in normal weight (P=0.01) and obese participants (P<0.001), but the scale of increase across tertiles was greater in obese adults. Main effects of fatty acid and inflammatory marker associations are also reported.

CONCLUSION

The modifying effect of obesity on the association of plasma PUFAs with IL-6 and sICAM-1 suggests differences in fatty acid metabolism and may also have implications in dietary fatty acid intake for obese individuals, particularly for linoleic and EPAs. Further study is warranted to confirm and explain the strong associations of DGLA with inflammatory and endothelial activation markers.

Clinical study of the effects on asthma-related QOL and asthma management of a medical food in adult asthma patients

BACKGROUND

Asthma can have a negative impact on quality of life although this is not well correlated with objective evaluations of pulmonary function. A medical food, EFF1009, containing the fatty acids gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA) decreases leukotriene B(4) synthesis in patients with asthma. Two previous clinical studies with EFF1009 provided preliminary evidence that the medical food improves asthma-related quality of life (ARQOL) and asthma management.

OBJECTIVE

To evaluate the impact on ARQOL of EFF1009 in adults with asthma.

RESEARCH DESIGN AND METHODS

The study was a randomized, prospective, double-blind, placebo-controlled, parallel group study in twenty-one (N = 21 evaluable) subjects with mild to moderate persistent asthma who consumed the medical food emulsion or placebo emulsion daily for 28 days. All participants continued their asthma medications throughout the study. ARQOL, including asthma signs and symptoms, and asthma control were measured using the Mini Asthma Quality of Life Questionnaire (MiniAQLQ) and the Asthma Control Questionnaire (ACQ), administered at baseline, Day 14 and Day 28. Safety and tolerability parameters, including adverse events, were monitored.

RESULTS

Baseline ARQOL scores, forced expiratory volume in one second (FEV(1)) and other characteristics were balanced between both groups. Mean (standard error) total MiniAQLQ scores changed by 0.73 (0.38) and -0.22 (0.36) in the EFF1009 and placebo groups, respectively, (p < 0.05). The MiniAQLQ symptom domain score was improved in the EFF1009 group (p < 0.05). Total scores for the ACQ were not significantly improved in either group. Levels of the fatty acid EPA in plasma increased in the EFF1009 group but not the placebo group (p < 0.03). The medical food was well tolerated and no safety concerns were identified.

CONCLUSIONS

The dietary addition of the medical food EFF1009 to asthma management regimens can improve patient perceived, ARQOL and can also improve asthma management as evidenced by reduced asthma symptoms. An additional study of the medical food, with larger subject population and longer treatment duration, is warranted to confirm these findings.

Oral supplementation with dihomo-gamma-linolenic acid-enriched oil altered serum fatty acids in healthy men

Dihomo-gamma-linolenic acid (DGLA)-enriched oil (50 or 150 mg as free DGLA) was administered to healthy men for 4 weeks. The DGLA content in serum phospholipids dose-dependently increased and returned to the initial level after a 4-week washout. No side effects or changes in platelet aggregation were observed. These results indicate that oral supplementation with DGLA oil can safely increase serum DGLA content.

Subchronic (13-week) oral toxicity study of dihomo-gamma-linolenic acid (DGLA) oil in rats

Dihomo-gamma-linolenic acid (DGLA) is one of the essential fatty acids, and has anti-inflammatory and anti-allergic effects. To assess the toxicity of a novel DGLA oil produced by the fungus Mortierella alpina, we examined it in the Ames test and in acute and subchronic oral toxicity tests in rats. In the Ames test, no mutagenicity was found up to 5000 microg/plate. The acute toxicity test revealed no toxicity related to DGLA oil at 10 g/kg. In the subchronic toxicity test, DGLA oil (500, 1000, and 2000 mg/kg) was orally administered. Water and soybean oil (2000 mg/kg) were used for the no-oil control and soybean oil control groups, respectively. There was no death in either sex. Because of administration of large amounts of oil, food consumption was low in the soybean oil control and the three test groups, which appeared to mildly decrease urinary excretion of Na, K, and Cl, as well as total serum protein, albumin, and blood urea nitrogen levels. There were no toxicological changes in body weight, food consumption, ophthalmological examination, urinalysis, hematological examination, blood biochemical examination, necropsy, organ weight, or histopathological examination. These findings show that the no-observed-adverse-effect level of the DGLA oil was 2000 mg/kg.

Oral administration of dihomo-gamma-linolenic acid prevents development of atopic dermatitis in NC/Nga mice

Disorders of the metabolism of essential fatty acids (EFAs) are related to atopic dermatitis (AD). Concentrations of dihomo-gamma-linolenic acid (DGLA), an EFA, in the serum of AD patients are lower than those in healthy volunteers. Recently we developed a fermented DGLA oil, and examined whether oral administration of DGLA prevents development of dermatitis in NC/Nga mice, which spontaneously develop human AD-like skin lesions. NC/Nga mice were fed a diet either containing or not containing DGLA for 8 weeks under in air-uncontrolled conventional circumstances. Clinical skin severity scores were significantly lower in mice fed DGLA than in mice not fed it. Scratching behavior and plasma total IgE levels were also reduced in the DGLA group, in association with histological improvement. DGLA suppressed clinical severity of skin lesions dose-dependently, with an increase in DGLA contents in phospholipids of skin, spleen, and plasma. Discontinuation of DGLA administration resulted in the onset of dermatitis and a decrease in DGLA contents in skin, spleen, and plasma. These findings indicate that oral administration of DGLA effectively prevents the development of AD in NC/Nga mice, and that DGLA in phospholipids is a compound of key importance in the development and prevention of dermatitis.

Heterologous production of dihomo-gamma-linolenic acid in Saccharomyces cerevisiae

To make dihomo-gamma-linolenic acid (DGLA) (20:3n-6) in Saccharomyces cerevisiae, we introduced Kluyveromyces lactis Delta12 fatty acid desaturase, rat Delta6 fatty acid desaturase, and rat elongase genes. Because Fad2p is able to convert the endogenous oleic acid to linoleic acid, this allowed DGLA biosynthesis without the need to supply exogenous fatty acids on the media. Medium composition, cultivation temperature, and incubation time were examined to improve the yield of DGLA. Fatty acid content was increased by changing the medium from a standard synthetic dropout medium to a nitrogen-limited minimal medium (NSD). Production of DGLA was higher in the cells grown at 15 degrees C than in those grown at 20 degrees C, and no DGLA production was observed in the cells grown at 30 degrees C. In NSD at 15 degrees C, fatty acid content increased up until day 7 and decreased after day 10. When the cells were grown in NSD for 7 days at 15 degrees C, the yield of DGLA reached 2.19 microg/mg of cells (dry weight) and the composition of DGLA to total fatty acids was 2.74%. To our knowledge, this is the first report describing the production of polyunsaturated fatty acids in S. cerevisiae without supplying the exogenous fatty acids.

Effects of Diet and Simvastatin on Fatty Acid Composition in Hypercholesterolemic Men

OBJECTIVE

To explore the separate and combined effects of simvastatin and a low-saturated diet rich in alpha-linolenic acid on serum fatty acids.

METHODS AND RESULTS

120 hypercholesterolemic men were randomly allocated to a habitual diet or dietary treatment group and to receive, in random order, simvastatin 20 mg/d or placebo, each for 12 weeks, in a double-blind manner. Dietary treatment decreased proportions from total fatty acids of palmitic acid (C16:0) by 3.3% (P<0.05), stearic acid (C18:0) by 3.7% (P<0.05) and increased proportions of oleic acid (C18:1n-9) by 4.2% (P<0.01), and alpha-linolenic acid (C18:3n-3) by 29.8% (P<0.001). Simvastatin decreased proportions from total fatty acids of palmitic acid by 2.0% (P<0.01), linoleic acid (C18:2n-6) by 5.3% (P<0.001), and alpha-linolenic acid by 6.8% (P<0.05), and increased proportions of gamma-linolenic acid (C18:3n-6) by 11.1% (P<0.001), dihomo-gamma-linolenic acid (C20:3n-6) by 4.2% (P<0.01), arachidonic acid (C20:4n-6) by 14.2% (P<0.001), and the sum of long-chain polyunsaturated fatty acids (C20-22) by 9.0% (P<0.001). Simvastatin increased ratios of stearic to palmitic, gamma-linolenic to linoleic, and arachidonic to dihomo-gamma-linolenic acid by 7.6%, 17.0%, and 10.0% (P<0.001 for all), respectively, suggesting increased fatty acid elongase and Delta6- and Delta5-desaturase enzyme activities.

CONCLUSIONS

Increased formation of long-chain polyunsaturated fatty acids and their metabolites may contribute a substantial part of the pleiotropic effects of simvastatin.

Sesamin inhibits lipopolysaccharide-induced cytokine production by suppression of p38 mitogen-activated protein kinase and nuclear factor-kappaB

Sesame seed oil increases the survival after cecal ligation and puncture in mice and the increased IL-10 levels with non-lethal lipopolysaccharides (LPS) challenge. We showed that sesamin and sesamolin, major lignans of sesame oil, regulated LPS-induced nitric oxide production in the murine microglia and BV-2 cell line. In this study, we studied the effect of sesamin on cytokine production by LPS stimulation. The result showed that sesamin significantly inhibited LPS-stimulated IL-6 mRNA and protein, and to a lesser degree TNF-alpha, in BV-2 microglia. Sesamin and sesamolin also reduced LPS-activated p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB activations. Furthermore, SB203580, a specific inhibitor of p38 MAP kinase, specifically inhibited LPS-induced IL-6 production. These results suggest that sesamin inhibited LPS-induced IL-6 production by suppression of p38 MAPK signal pathway and NF-kappaB activation.

Dihomo-gamma-linolenic acid inhibits tumour necrosis factor-alpha production by human leucocytes independently of cyclooxygenase activity

Dietary oils (such as borage oil), which are rich in gamma-linolenic acid (GLA), have been shown to be beneficial under inflammatory conditions. Dihomo-GLA (DGLA) is synthesized directly from GLA and forms a substrate for cyclooxygenase (COX) enzymes, resulting in the synthesis of lipid mediators (eicosanoids). In the present study, the immunomodulatory effects of DGLA were investigated and compared with those of other relevant fatty acids. Freshly isolated human peripheral blood mononuclear cells (PBMC) were cultured in fatty acid (100 microm)-enriched medium for 48 hr. Subsequently, cells were stimulated with lipopolysaccharide (LPS) for 20 hr and the cytokine levels were measured, in supernatants, by enzyme-linked immunosorbent assay (ELISA). Phospholipids were analysed by gas chromatography. Fatty acids were readily taken up, metabolized and incorporated into cellular phospholipids. Compared with the other fatty acids tested, DGLA exerted pronounced modulatory effects on cytokine production. Tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-10 levels were reduced to 60% of control levels, whereas IL-6 levels were not affected by DGLA. Kinetic studies showed that peak levels of TNF-alpha, occurring early after LPS addition, were inhibited strongly, whereas IL-10 levels were not affected until 15 hr after stimulation. Both the reduction of cytokine levels and the decrease in arachidonic acid levels in these cells, induced by DGLA, were dose dependent, suggesting a shift in eicosanoid-subtype synthesis. However, although some DGLA-derived eicosanoids similarly reduced TNF-alpha levels, the effects of DGLA were probably not mediated by COX products, as the addition of indomethacin did not alter the effects of DGLA. In conclusion, these results suggest that DGLA affects cytokine production by human PBMC independently of COX activation.

Local application of n-3 or n-6 polyunsaturated fatty acids in the treatment of human experimental gingivitis

BACKGROUND

Polyunsaturated fatty acids have the potential to attenuate inflammation by the synthesis of mediators of the 15-lipoxygenase pathways, which show opposite effects to the pro-inflammatory arachidonic acid metabolites such as leukotriene B4 (LTB4).

AIMS

The aim of this clinical study was to evaluate the effects of topical application of n-6 or n-6 polyunsaturated fatty acids in patients with experimental gingivitis.

METHODS

In each subject, similar teeth served as experimental and control over a 21-day non-hygiene phase and a 9-day resolving phase. Efficacy assessment was based on the bleeding on probing frequency (BOP) and the gingivocrevicular fluid volume (GCF). GCF was determined by inserting a filter paper strip for 30 s and measurements were performed on a Periotron 8000. The LTB4 concentration was analyzed by reversed-phase high-pressure liquid chromatography.

RESULTS

After 21 days of plaque growth, the BOP, GCF and LTB4 levels were significantly increased in all groups, with no differences between the control and experimental side. Rinsing of an area with established gingivitis for a 9-day period significantly reduced the GCF in the n-6 group (71.9 (18.7) versus 47.4 (11.4) Periotron Units, median (inter quartile range)).

CONCLUSION

The topical application of n-6 or n-6 fatty acids failed to inhibit the development of experimental gingivitis. Rinsing with n-6 fatty acids could reduce the level of GCF in established experimental gingivitis.

Fatty acids and lymphocyte functions

The immune system acts to protect the host against pathogenic invaders. However, components of the immune system can become dysregulated such that their activities are directed against host tissues, so causing damage. Lymphocytes are involved in both the beneficial and detrimental effects of the immune system. Both the level of fat and the types of fatty acid present in the diet can affect lymphocyte functions. The fatty acid composition of lymphocytes, and other immune cells, is altered according to the fatty acid composition of the diet and this alters the capacity of those cells to produce eicosanoids, such as prostaglandin E2, which are involved in immunoregulation. A high fat diet can impair lymphocyte function. Cell culture and animal feeding studies indicate that oleic, linoleic, conjugated linoleic, gamma-linolenic, dihomo-gamma-linolenic, arachidonic, alpha-linolenic, eicosapentaenoic and docosahexaenoic acids can all influence lymphocyte proliferation, the production of cytokines by lymphocytes, and natural killer cell activity. High intakes of some of these fatty acids are necessary to induce these effects. Among these fatty acids the long chain n-3 fatty acids, especially eicosapentaenoic acid, appear to be the most potent when included in the human diet. Although not all studies agree, it appears that fish oil, which contains eicosapentaenoic acid, down regulates the T-helper 1-type response which is associated with chronic inflammatory disease. There is evidence for beneficial effects of fish oil in such diseases; this evidence is strongest for rheumatoid arthritis. Since n-3 fatty acids also antagonise the production of inflammatory eicosanoid mediators from arachidonic acid, there is potential for benefit in asthma and related diseases. Recent evidence indicates that fish oil may be of benefit in some asthmatics but not others.

Addition of eicosapentaenoic acid to gamma-linolenic acid-supplemented diets prevents serum arachidonic acid accumulation in humans

Previous studies reveal that supplementation of human diets with gamma-linolenic acid (GLA) reduces the generation of lipid mediators of inflammation and attenuates clinical symptoms of chronic inflammatory disorders such as rheumatoid arthritis. However, we have shown that supplementation with this same fatty acid also causes a marked increase in serum arachidonate (AA) levels, a potentially harmful side effect. The objective of this study was to design a supplementation strategy that maintained the capacity of GLA to reduce lipid mediators without causing elevations in serum AA levels. Initial in vitro studies utilizing HEP-G2 liver cells revealed that addition of eicosapentaenoic acid (EPA) blocked Delta-5-desaturase activity, the terminal enzymatic step in AA synthesis. To test the in vivo effects of a GLA and EPA combination in humans, adult volunteers consuming controlled diets supplemented these diets with 3.0 g/d of GLA and EPA. This supplementation strategy significantly increased serum levels of EPA, but did not increase AA levels. EPA and the elongation product of GLA, dihomo-gamma-linolenic acid (DGLA) levels in neutrophil glycerolipids increased significantly during the 3-wk supplementation period. Neutrophils isolated from volunteers fed diets supplemented with GLA and EPA released similar quantities of AA, but synthesized significantly lower quantities of leukotrienes compared with their neutrophils before supplementation. This study revealed that a GLA and EPA supplement combination may be utilized to reduce the synthesis of proinflammatory AA metabolites, and importantly, not induce potentially harmful increases in serum AA levels.

Dietary supplementation with gamma-linolenic acid alters fatty acid content and eicosanoid production in healthy humans

To understand the in vivo metabolism of dietary gamma-linolenic acid (GLA), we supplemented the diets of 29 volunteers with GLA in doses of 1.5-6.0 g/d. Twenty-four subjects ate controlled eucaloric diets consisting of 25% fat; the remaining subjects maintained their typical Western diets. GLA and dihomo-gamma-linolenic acid (DGLA) increased in serum lipids of subjects supplemented with 3.0 and 6.0 g/d; serum arachidonic acid increased in all subjects. GLA supplementation with 3.0 and 6.0 g/d also resulted in an enrichment of DGLA in neutrophil phospholipids but no change in GLA or AA levels. Before supplementation, DGLA was associated primarily with phosphatidylethanolamine (PE) of neutrophil glycerolipids, and DGLA increased significantly in PE and neutral lipids after GLA supplementation. Extending the supplementation to 12 wk did not consistently change the magnitude of increase in either serum or neutrophil lipids in subjects receiving 3.0 g/d. After GLA supplementation, A23187-stimulated neutrophils released significantly more DGLA, but AA release did not change. Neutrophils obtained from subjects after 3 wk of supplementation with 3.0 g/d GLA synthesized less leukotriene B4 (P < 0.05) and platelet-activating factor. Together, these data reveal that DGLA, the elongase product of GLA, but not AA accumulates in neutrophil glycerolipids after GLA supplementation. The increase in DGLA relative to AA within inflammatory cells such as the neutrophil may attenuate the biosynthesis of AA metabolites and may represent a mechanism by which dietary GLA exerts an anti-inflammatory effect.

Prophylactic treatment of migraine with gamma-linolenic and alpha-linolenic acids

Polyunsaturated fatty acids (PUFA) were administered to 168 patients over a period of 6 months in an open-label uncontrolled study. In 129 patients available for study, 86% experienced reduction in severity, frequency and duration of migraine attacks, 22% became free of migraine and more than 90% had reduced nausea and vomiting. Self-medication changed to simple analgesics in the majority except in 14% of patients without improvement.

Botanical lipids: effects on inflammation, immune responses, and rheumatoid arthritis

OBJECTIVE

This review discusses the rationale and experimental data that led to clinical trials of certain botanical lipids, mainly gammalinolenic acid (GLA), for the treatment of rheumatoid arthritis (RA).

DATA SOURCES

Pertinent articles and reviews, and a bibliographic database in English using the following indexing terms: rheumatoid arthritis, fatty acids, gammalinolenic acid, lymphocytes, and monocytes, were used.

STUDY SELECTION

All clinical trials in which GLA was used to treat arthritis are included in this review. Data from appropriately peer reviewed in vitro and animal experiments evaluating the effects of botanical lipids as regulators of cell activation and immune responses are also reviewed.

DATA SYNTHESIS

GLA treatment is associated with clinical improvement in patients with RA, as evaluated by duration of morning stiffness, joint pain and swelling, and ability to reduce other medications. However, studies vary in terms of duration, GLA dose, whether or not they were placebo controlled, and, if so, what placebo was used, criteria for evaluation, and use of concomitant medication. Studies done in vitro generally indicated that GLA reduces lymphocyte activation and production of mediators of inflammation.

CONCLUSIONS

A small number of studies suggest that GLA is effective treatment for RA patients. Further controlled studies of its use in RA seem warranted.

Effects of linoleic acid and gamma-linolenic acid on the growth and metastasis of a human breast cancer cell line in nude mice and on its growth and invasive capacity in vitro

It has been reported that gamma-linolenic acid (GLA)-rich diets suppress mammary carcinogenesis and transplanted tumor growth and that GLA inhibits the growth of cultured human cancer cell lines. We compared the effects of dietary GLA and linoleic acid (LA) on the growth of MDA-MB-435 human breast cancer cells and their expression of the metastatic phenotype in vivo and in vitro. Athymic nude mice (30/dietary group) were fed isocaloric diets containing 20% (wt/wt) fat but providing 8% GLA or LA for 7 days, and 10(6) tumor cells were then injected into a thoracic mammary fat pad. The diets were continued for a further 11 weeks. The primary tumor growth rates were similar in mice from the two dietary groups; there was a nonstatistically significant trend for the incidence of macroscopic lung metastases and the total lung metastatic volumes to be higher in the GLA-fed mice (79% and 40.1 +/- 13.9 mm3) than in the LA-fed mice (64% and 15.5 +/- 5.4 mm3). The tumor cell phospholipids from the 8% GLA-fed mice contained significantly lower LA levels but higher arachidonic acid levels (both p < 0.001) than those from 8% LA-fed mice. Also the arachidonate-derived eicosanoids (prostaglandin E, leukotriene B4, and 5-, 12-, and 15-hydroxyeicosatetraenoic acids) were significantly higher in tumors from the 8% GLA group. Zymography showed higher 92-kDa type IV collagenase activity in tumors from 8% GLA-fed mice. In vitro, GLA and LA, at 0.5-2 micrograms/ml, stimulated MDA-MB-435 cell growth; 10 micrograms/ml was mildly inhibitory. Whereas LA stimulated tumor cell invasion and 92-kDa type IV collagenase production in vitro, GLA inhibited invasion and did not induce activity of the proteolytic enzyme. Our results do not support the hypothesis that supplementation with GLA would exert a beneficial effect on the progression of an existing breast cancer, perhaps because it is metabolized in vivo to arachidonate-derived eicosanoids that are known to be involved in the metastatic process.