Fatty Acid-derived Lipid Mediators Research Articles

Joint effects of one year of marine omega-3 fatty acid supplementation and participant dietary fish intake upon circulating lipid mediators of inflammation resolution in a randomized controlled trial

We assessed the joint effects of omega (n)-3 fatty acid supplementation and dietary fish intake on systemic lipid mediators of inflammation among adults. Within VITAL, a double-blind randomized controlled trial, adults were randomized to ω-3 fatty acids (460 mg EPA + 380 mg DHA/d) or placebo. We selected participants who reported low (<1 serving/mo) baseline dietary fish intake and matched them by age, sex, race, and trial arm to participants with self-reported highest fish intake (≥3.9 servings/wk). Baseline and 1-y plasma samples were tested for 9 ω-3 fatty acid-derived lipid mediators. Multivariable linear models assessed lipid mediator changes and joint effects of ω-3 fatty acid supplementation and dietary fish intake. Forty-eight participants with low baseline fish intake were matched to 48 with high fish intake. Mean age was 64.6 (±7.26), 50% were female, and 85% non-Hispanic white. One-year lipid mediator changes in expected directions were observed in those receiving ω-3 fatty acids versus placebo: reductions in proinflammatory mediators, PGD2, 5-HETE, and 12-HETE; increases in proresolving mediators, EPA and DHA. Larger 1-y lipid biomarker changes were seen in those with low baseline fish intake randomized to active ω-3 fatty acids for DHA, EPA, PGD2, Resolvin D1, and Resolvin D4 were observed, although no significant multiplicative interactions were detected. Beneficial changes in circulating proresolving and proinflammatory mediators were found with 1-y of ω-3 fatty acid supplementation versus placebo for all participants, with a trend toward larger effects among those with low baseline fish intake, although interactions were not significant.

Polyunsaturated Fatty Acid-Derived Lipid Mediators as Potential Biomarkers for Leprosy Among Individuals with Asymptomatic Mycobacterium leprae Infection.

Intra-household contacts (HCs) of leprosy patients are at increased risk of infection by Mycobacterium leprae and about ∼5-10% will develop active disease. A prognostic tool to identify HCs with the greatest risk of progressing to active disease would enhance early leprosy diagnosis and optimize prophylactic intervention. Previous metabolomics studies suggest that host lipid mediators derived from ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) are potential biomarkers for leprosy. In this study, we investigated retrospective sera of leprosy HCs by liquid chromatography-mass spectrometry and enzyme-linked immunoassay to determine whether circulating levels of ω-3 and ω-6 PUFA metabolites were altered in HCs that developed leprosy (HCDL) in comparison to those that did not (HCNDL). Sera were collected from HCs at the time of index case diagnosis and before clinical signs/symptoms of leprosy. Our findings showed that HCDL sera exhibited a distinct metabolic profile in comparison to HCDNL. Specifically, arachidonic acid, leukotriene B4, 11-hydroxyeicosatetraenoic acid, prostaglandin D2, and lipoxin A4 were elevated in HCDL. In contrast, prostaglandin E2 levels were reduced in HCDL. The ω-3 PUFAs, docosahexaenoic acid, eicosapentaenoic acid, and the docosahexaenoic acid-derived resolvin D1 and maresin-1 were also elevated in HCDL individuals compared to HCNDL. Principal component analyses provided further evidence that lipid mediators could serve as an early biomarker for progression to active leprosy. A logistic model identified resolvin D1 and D2, and prostaglandin D2 as having the greatest potential for early detection of HCs that will manifest leprosy.

Polyunsaturated Fatty Acid-Derived Lipid Mediators That Regulate Epithelial Homeostasis.

Epithelial tissues are mainly composed of epithelial cells, covering both internal and external surfaces of our body. To maintain epithelial homeostasis, cellular functions, such as proliferation, migration, and differentiation, are flexibly regulated in response to changes in the cellular status, thereby contributing to barrier formation, immune reaction, and wound closure. Polyunsaturated fatty acids (PUFAs) are precursors of various lipid mediators that maintain tissue homeostasis by exerting characteristic bioactivities. This review aimed to summarize the role of PUFA-derived lipid mediators in epithelial cell functions, mainly focusing on the epidermis, cornea, and intestinal epithelium.

Aspirin-Triggered Resolvin D1 Reduces Chronic Dust-Induced Lung Pathology without Altering Susceptibility to Dust-Enhanced Carcinogenesis.

Simple SummaryFarm workers are at an increased risk of developing acute and chronic lung inflammatory diseases from their everyday exposure to organic dust. Previous investigations have examined the inflammatory effects in mice from single and repetitive exposure to dust from swine confinement facilities, however, no study has explored these effects in a chronic model. To address this research gap, we established a chronic dust exposure mouse model of lung tumorigenesis that was also used to measure the efficacy of omega-3 fatty acid-derived lipid mediators as therapeutics for mitigating these induced responses. Our results from these investigations are the first to evaluate the chronic inflammatory, and carcinogenic effects of these dusts, as well as identify a potential therapeutic strategy for mitigating the inflammatory effects by using an omega-3 fatty acid-derived bioactive lipid mediator.Lung cancer is the leading cause of cancer-related deaths worldwide, with increased risk being associated with unresolved or chronic inflammation. Agricultural and livestock workers endure significant exposure to agricultural dusts on a routine basis; however, the chronic inflammatory and carcinogenic effects of these dust exposure is unclear. We have developed a chronic dust exposure model of lung carcinogenesis in which mice were intranasally challenged three times a week for 24 weeks, using an aqueous dust extract (HDE) made from dust collected in swine confinement facilities. We also treated mice with the omega-3-fatty acid lipid mediator, aspirin-triggered resolvin D1 (AT-RvD1) to provide a novel therapeutic strategy for mitigating the inflammatory and carcinogenic effects of HDE. Exposure to HDE resulted in significant immune cell influx into the lungs, enhanced lung tumorigenesis, severe tissue pathogenesis, and a pro-inflammatory and carcinogenic gene signature, relative to saline-exposed mice. AT-RvD1 treatment mitigated the dust-induced inflammatory response but did not protect against HDE + NNK-enhanced tumorigenesis. Our data suggest that chronic HDE exposure induces a significant inflammatory and pro-carcinogenic response, whereas treatment with AT-RvD1 dampens the inflammatory responses, providing a strong argument for the therapeutic use of AT-RvD1 to mitigate chronic inflammation.

LSEA Evaluation of Lipid Mediators of Inflammation in Lung and Cortex of Mice Exposed to Diesel Air Pollution.

Airborne ultrafine particle (UFP) exposure is a great concern as they have been correlated to increased cardiovascular mortality, neurodegenerative diseases and morbidity in occupational and environmental settings. The ultrafine components of diesel exhaust particles (DEPs) represent about 25% of the emission mass; these particles have a great surface area and consequently high capacity to adsorb toxic molecules, then transported throughout the body. Previous in-vivo studies indicated that DEP exposure increases pro- and antioxidant protein levels and activates inflammatory response both in respiratory and cardiovascular systems. In cells, DEPs can cause additional reactive oxygen species (ROS) production, which attacks surrounding molecules, such as lipids. The cell membrane provides lipid mediators (LMs) that modulate cell-cell communication, inflammation, and resolution processes, suggesting the importance of understanding lipid modifications induced by DEPs. In this study, with a lipidomic approach, we evaluated in the mouse lung and cortex how DEP acute and subacute treatments impact polyunsaturated fatty acid-derived LMs. To analyze the data, we designed an ad hoc bioinformatic pipeline to evaluate the functional enrichment of lipid sets belonging to the specific biological processes (Lipid Set Enrichment Analysis-LSEA). Moreover, the data obtained correlate tissue LMs and proteins associated with inflammatory process (COX-2, MPO), oxidative stress (HO-1, iNOS, and Hsp70), involved in the activation of many xenobiotics as well as PAH metabolism (Cyp1B1), suggesting a crucial role of lipids in the process of DEP-induced tissue damage.

Plant Sterol-Poor Diet Is Associated with Pro-Inflammatory Lipid Mediators in the Murine Brain.

Plant sterols (PSs) cannot be synthesized in mammals and are exclusively diet-derived. PSs cross the blood-brain barrier and may have anti-neuroinflammatory effects. Obesity is linked to lower intestinal uptake and blood levels of PSs, but its effects in terms of neuroinflammation—if any—remain unknown. We investigated the effect of high-fat diet-induced obesity on PSs in the brain and the effects of the PSs campesterol and β-sitosterol on in vitro microglia activation. Sterols (cholesterol, precursors, PSs) and polyunsaturated fatty acid-derived lipid mediators were measured in the food, blood, liver and brain of C57BL/6J mice. Under a PSs-poor high-fat diet, PSs levels decreased in the blood, liver and brain (>50%). This effect was reversible after 2 weeks upon changing back to a chow diet. Inflammatory thromboxane B2 and prostaglandin D2 were inversely correlated to campesterol and β-sitosterol levels in all brain regions. PSs content was determined post mortem in human cortex samples as well. In vitro, PSs accumulate in lipid rafts isolated from SIM-A9 microglia cell membranes. In summary, PSs levels in the blood, liver and brain were associated directly with PSs food content and inversely with BMI. PSs dampen pro-inflammatory lipid mediators in the brain. The identification of PSs in the human cortex in comparable concentration ranges implies the relevance of our findings for humans.

Specialized Proresolving Mediators in Symptomatic Women With Coronary Microvascular Dysfunction (from the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD [WARRIOR] Trial)

Resolvins and maresins, members of the specialized proresolving mediator (SPM) family, are omega-3 fatty acid-derived lipid mediators that attenuate inflammation. We hypothesized that they play a role in the pathophysiology of coronary microvascular dysfunction (CMD) in women with ischemia and no obstructive coronary disease. In a pilot study, we measured the D-series resolvins (D1, D2, D3, and D5), resolvin E1, maresin 1, docosahexaenoic acid, eicosapentaenoic acid (precursor of resolvin E1), and 18-hydroxyeicosapentaenoic acid by mass spectrometry in the peripheral blood of 31 women enrolled in the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD (WARRIOR) trial who had confirmed CMD assessed by coronary flow reserve. We compared SPM levels with 12 gender and age-matched reference subjects. Compared with the reference subject group, those with CMD had significantly lower plasma concentrations of resolvin D1 and maresin 1 and significantly higher levels of docosahexaenoic acid and 18-hydroxyeicosapentaenoic acid. In conclusion, insufficient or ineffective SPM production may play a role in the pathophysiology of CMD. If our results are validated in a larger cohort, omega-3 fatty acid supplementation could be tested as a novel treatment for these patients.

Dysregulated Maresin Concentrations in Plasma and Nasal Secretions From Patients With Chronic Rhinosinusitis.

The mechanisms that lead to disease onset and propagation in patients with chronic rhinosinusitis (CRS) are not fully elucidated. Maresins (MaR) are a family of essential fatty acid-derived lipid mediators that play a central role in the regulation of inflammation with several studies demonstrating that these mediators display protective activities in airway inflammation. Therefore, in the present studies we evaluated whether concentrations of these mediators were altered in both peripheral blood and nasal secretions from CRS patients. Herein, we focused on patients with CRS that also develop nasal polyps (CRSwNP), given that therapeutic options for the treatment of these patients are limited. Thereby, insights into disease mechanisms in these patients may help design more effective treatments. For this purpose, we compared maresin concentrations from CRSwNP patients with those found in healthy volunteers or patients with an upper respiratory tract infection (URTI), as a self-resolving inflammatory condition. Using liquid chromatography tandem mass spectrometry, we found that MaR concentrations were significantly decreased in plasma from patients with CRSwNP when compared to healthy volunteers. MaR concentrations were observed to be significantly upregulated in nasal secretions from patients with CRSwNP when compared with both healthy volunteers and URTI subjects. Concentration of these mediators in both plasma and nasal secretions from CRSwNP patients were positively correlated with quality-of-life scores in these patients. Assessment of the concentrations of other pro-resolving and pro-inflammatory lipid mediators (LM) demonstrated that there was a general shift in LM levels in both plasma and nasal secretions from CRSwNP when compared with healthy volunteers and URTI subjects. Of note, incubation of peripheral blood cells from CRSwNP patients with MaR1 downregulated the expression of activation markers on peripheral blood phagocytes, including CD41 and CD62P, markers of platelet-leukocyte heterotypic aggregates. Together these findings demonstrate that both local and systemic LM concentrations, in particularly those of the MaR family, become altered in patients with CRSwNP. They also suggest that therapeutics designed around MaR1 may be useful in regulating the activation of phagocytes in patients with CRSwNP thereby potentially also limiting the local inflammatory response in these patients.

Disrupted Resolution Mechanisms Favor Altered Phagocyte Responses in COVID-19

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Lipid Mediators in Critically Ill Patients: A Step Towards Precision Medicine.

A dysregulated response to systemic inflammation is a common pathophysiological feature of most conditions encountered in the intensive care unit (ICU). Recent evidence indicates that a dysregulated inflammatory response is involved in the pathogenesis of various ICU-related disorders associated with high mortality, including sepsis, acute respiratory distress syndrome, cerebral and myocardial ischemia, and acute kidney injury. Moreover, persistent or non-resolving inflammation may lead to the syndrome of persistent critical illness, characterized by acquired immunosuppression, catabolism and poor long-term functional outcomes. Despite decades of research, management of many disorders in the ICU is mostly supportive, and current therapeutic strategies often do not take into account the heterogeneity of the patient population, underlying chronic conditions, nor the individual state of the immune response. Fatty acid-derived lipid mediators are recognized as key players in the generation and resolution of inflammation, and their signature provides specific information on patients’ inflammatory status and immune response. Lipidomics is increasingly recognized as a powerful tool to assess lipid metabolism and the interaction between metabolic changes and the immune system via profiling lipid mediators in clinical studies. Within the concept of precision medicine, understanding and characterizing the individual immune response may allow for better stratification of critically ill patients as well as identification of diagnostic and prognostic biomarkers. In this review, we provide an overview of the role of fatty acid-derived lipid mediators as endogenous regulators of the inflammatory, anti-inflammatory and pro-resolving response and future directions for use of clinical lipidomics to identify lipid mediators as diagnostic and prognostic markers in critical illness.

Distinct Profiles of Specialized Pro-resolving Lipid Mediators and Corresponding Receptor Gene Expression in Periodontal Inflammation.

Polyunsaturated fatty acid-derived specialized pro-resolving lipid mediators (SPMs) play an important role in modulating inflammation. The aim of the study was to compare profiles of SPMs, SPM related lipid mediators and SPM receptor gene expression in gingiva of subjects with periodontitis to healthy controls. A total of 28 subjects were included; 13 periodontally healthy and 15 periodontitis before or after non-surgical periodontal therapy. Gingival tissues were collected from two representative posterior teeth prior to and 8 weeks after scaling and root planning; only once in the healthy group. Lipid mediator-SPM metabololipidomics was performed to identify metabolites in gingiva. qRT-PCR was performed to assess relative gene expression (2−ΔΔCT) of known SPM receptors. Intergroup comparisons were made using Wilcoxon tests. Thirty-six omega-6 or omega-3 fatty acid-derived lipid mediators and seven receptor genes were identified in gingiva. Profiles of lipid mediators and receptor gene expression were significantly different between the three groups. Levels of six lipid mediators, 5-HETE, 15-HETE, 15(S)-HEPE, 4-HDHA, 7-HDHA, and 17-HDHA in periodontitis before treatment were significantly higher than in periodontitis after treatment. The expression of BLT1 in the healthy group was significantly higher than periodontitis subjects before and after treatment. The expression of GPR18 in periodontitis before treatment was significantly higher than in periodontitis after treatment while the expression of GPR32 in periodontitis before treatment was significantly lower than in periodontitis after treatment. Elevated levels of SPM biosynthetic pathway markers in periodontitis subjects before treatment indicated inflammation induced pro-resolution activity in gingiva, but receptors for these molecules were deficient in periodontitis pre-treatment suggesting that failure of resolution of inflammation contributes to excess, chronic inflammation in periodontitis.

Omega-3 Polyunsaturated Fatty Acid Derived Lipid Mediators and their Application in Drug Discovery.

Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) play crucial and often opposing regulatory roles in health and in pathological conditions. n-3 and n-6 PUFA undergo biotransformation to parallel series of lipid mediators that are potent modulators of many cellular processes. A wide range of biological actions have been attributed to lipid mediators derived from n-6 PUFA, and these mediators have served as lead compounds in the development of numerous clinically approved drugs, including latanoprost (Xalatan: Pfizer), which is listed on the WHO Model List of Essential Medicines. n-3 PUFA-derived mediators have received less attention, in part because early studies suggested that n-3 PUFA act simply as competitive substrates for biotransformation enzymes and decrease the formation of n-6 PUFA-derived lipid mediators. However, more recent studies suggest that n-3 PUFA-derived mediators are biologically important in their own right. It is now emerging that many n-3 PUFA-derived lipid mediators have potent and diverse activities that are distinct from their n-6 counterparts. These findings provide new opportunities for drug discovery. Herein, we review the biosynthesis of n-3 PUFA-derived lipid mediators and highlight their biological actions that may be exploited for drug development. Lastly, we provide examples of medicinal chemistry research that has utilized n-3 PUFA-derived lipid mediators as novel lead compounds in drug design.

Leprosy and its reactional episodes: Serum levels and possible roles of omega-3 and omega-6-derived lipid mediators

The disease leprosy is caused by Mycobacterium leprae. The disease displays a spectrum of clinical manifestations relating to the stage of the infection and the pathogen-specific immune response. The most frequent M. leprae-specific hypersensitivity reactions are erythema nodosum leprosum (ENL) and type-1 (reversal) reaction (T1R). Omega-3 and omega-6 fatty acid-derived lipid mediators are involved in the regulation of these M. leprae-specific inflammatory and immune responses. Studies on lipid mediators showed their presence during different manifestations of leprosy-before and after multidrug therapy (MDT) and during T1R. This review aims to compare the lipid mediators at different stages of the disease. This review also presents new data on the significance of lipid mediators (cysteinyl leukotrienes and leukotriene B4, prostaglandin E2 and D2, lipoxin A4 and resolvin D1) on ENL.

Resolvin E1, resolvin D1 and resolvin D2 inhibit constriction of rat thoracic aorta and human pulmonary artery induced by the thromboxane mimetic U46619

The ω-6 fatty acid-derived lipid mediators such as prostanoids, thromboxane and leukotrienes have well-established roles in regulating both inflammation and smooth muscle contractility. Resolvins are derived from ω-3 fatty acids and have important roles in promoting the resolution of inflammation, but their activity on smooth muscle contractility is unknown. We investigated whether resolvin E1 (RvE1), resolvin D1 (RvD1) and resolvin D2 (RvD2) can modulate contractions of isolated segments of rat thoracic aorta (RTA) or human pulmonary artery (HPA) induced by the α1 -adrenoceptor agonist phenylephrine or the stable thromboxane A2 mimetic U46619. Contractile responses in RTA and HPA were measured using wire myography. Receptor expression was investigated by immunohistochemistry. Constriction of RTA segments by U46619, but not by phenylephrine, was significantly inhibited by pretreatment for 1 or 24h with 10-100nM RvE1, RvD1 or RvD2. The inhibitory effect of RvE1 was partially blocked by a chemerin receptor antagonist (CCX832). RvE1 at only 1-10nM also significantly inhibited U46619-induced constriction of HPA segments, and the chemerin receptor, GPR32 and FPR2/ALX were identified in HPA smooth muscle. These data suggest that resolvins or their mimetics may prove useful novel therapeutics in diseases such as pulmonary arterial hypertension, which are characterized by increased thromboxane contractile activity.

N-Docosahexaenoyl Dopamine, an Endocannabinoid-like Conjugate of Dopamine and the n-3 Fatty Acid Docosahexaenoic Acid, Attenuates Lipopolysaccharide-Induced Activation of Microglia and Macrophages via COX-2.

Several studies indicate that the n-3 long-chain polyunsaturated fatty acid docosahexaenoic acid (DHA) contributes to an attenuated inflammatory status in the development of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease. To explain these effects, different mechanisms are being proposed, including those involving endocannabinoids and related signaling molecules. Many of these compounds belong to the fatty acid amides, conjugates of fatty acids with biogenic amines. Conjugates of DHA with ethanolamine or serotonin have previously been shown to possess anti-inflammatory and potentially neuroprotective properties. Here, we synthesized another amine conjugate of DHA, N-docosahexaenoyl dopamine (DHDA), and tested its immune-modulatory properties in both RAW 264.7 macrophages and BV-2 microglial cells. N-Docosahexaenoyl dopamine significantly suppressed the production of nitric oxide (NO), the cytokine interleukin-6 (IL-6), and the chemokines macrophage-inflammatory protein-3α (CCL20) and monocyte chemoattractant protein-1 (MCP-1), whereas its parent compounds, dopamine and DHA, were ineffective. Further exploration of potential effects of DHDA on key inflammatory mediators revealed that cyclooxygenase-2 (COX-2) mRNA level and production of prostaglandin E2 (PGE2) were concentration-dependently inhibited in macrophages. In activated BV-2 cells, PGE2 production was also reduced, without changes in COX-2 mRNA levels. In addition, DHDA did not affect NF-kB activity in a reporter cell line. Finally, the immune-modulatory activities of DHDA were compared with those of N-arachidonoyl dopamine (NADA) and similar potencies were found in both cell types. Taken together, our data suggest that DHDA, a potentially endogenous endocannabinoid, may be an additional member of the group of immune-modulating n-3 fatty acid-derived lipid mediators.

MerTK cleavage limits proresolving mediator biosynthesis and exacerbates tissue inflammation

The acute inflammatory response requires a coordinated resolution program to prevent excessive inflammation, repair collateral damage, and restore tissue homeostasis, and failure of this response contributes to the pathology of numerous chronic inflammatory diseases. Resolution is mediated in part by long-chain fatty acid-derived lipid mediators called specialized proresolving mediators (SPMs). However, how SPMs are regulated during the inflammatory response, and how this process goes awry in inflammatory diseases, are poorly understood. We now show that signaling through the Mer proto-oncogene tyrosine kinase (MerTK) receptor in cultured macrophages and in sterile inflammation in vivo promotes SPM biosynthesis by a mechanism involving an increase in the cytoplasmic:nuclear ratio of a key SPM biosynthetic enzyme, 5-lipoxygenase. This action of MerTK is linked to the resolution of sterile peritonitis and, after ischemia-reperfusion (I/R) injury, to increased circulating SPMs and decreased remote organ inflammation. MerTK is susceptible to ADAM metallopeptidase domain 17 (ADAM17)-mediated cell-surface cleavage under inflammatory conditions, but the functional significance is not known. We show here that SPM biosynthesis is increased and inflammation resolution is improved in a new mouse model in which endogenous MerTK was replaced with a genetically engineered variant that is cleavage-resistant (Mertk(CR)). Mertk(CR) mice also have increased circulating levels of SPMs and less lung injury after I/R. Thus, MerTK cleavage during inflammation limits SPM biosynthesis and the resolution response. These findings contribute to our understanding of how SPM synthesis is regulated during the inflammatory response and suggest new therapeutic avenues to boost resolution in settings where defective resolution promotes disease progression.

The research progress of resolvin reducing pulmonary inflammation

Background Moderate inflammatory response is a kind of protective defense mechanism,however,uncontrolled inflammation may give rise to tissue damage.Resolvin,a kind of polyunsaturated fatty acid-derived lipid mediators,exhibit anti-inflammatory and pro-resolving functions,which can alleviate pulmonary inflammatiory diseases,such as acute lung injury,asthma,chronic obstructive pulmonary disease.Objective This review lay the foundations for the research of Resolvin in pulmonary inflammatory diseases.Content This review describes the production,classification and molecular structure of Resolvin.In addition,we summarize the mechanisms of Resolvin in reducing pulmonary inflammatory diseases.Trend With the development in resolvin research,it's possible that pro-resolving mediators be a new drug in the treatment of pulmonary inflammatory diseases. Key words: Resolvin;  Inflammation;  Pulmonary diseases

High-fat meals rich in EPA plus DHA compared with DHA only have differential effects on postprandial lipemia and plasma 8-isoprostane F2α concentrations relative to a control high–oleic acid meal: a randomized controlled trial

Background: Eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) supplementation has beneficial cardiovascular effects, but postprandial influences of these individual fatty acids are unclear.Objectives: The primary objective was to determine the vascular effects of EPA + DHA compared with DHA only during postprandial lipemia relative to control high–oleic acid meals; the secondary objective was to characterize the effects of linoleic acid–enriched high-fat meals relative to the control meal.Design: We conducted a randomized, controlled, double-blind crossover trial of 4 high-fat (75-g) meals containing 1) high–oleic acid sunflower oil (HOS; control), 2) HOS + fish oil (FO; 5 g EPA and DHA), 3) HOS + algal oil (AO; 5 g DHA), and 4) high–linoleic acid sunflower oil (HLS) in 16 healthy men (aged 35–70 y) with higher than optimal fasting triacylglycerol concentrations (mean ± SD triacylglycerol, 1.9 ± 0.5 mmol/L).Results: Elevations in triacylglycerol concentration relative to baseline were slightly reduced after FO and HLS compared with the HOS control (P < 0.05). The characteristic decrease from baseline in plasma nonesterified fatty acids after a mixed meal was inhibited after AO (Δ 0–3 h, P < 0.05). HLS increased the augmentation index compared with the other test meals (P < 0.05), although the digital volume pulse–reflection index was not significantly different. Plasma 8-isoprostane F2α analysis revealed opposing effects of FO (increased) and AO (reduced) compared with the control (P < 0.05). No differences in nitric oxide metabolites were observed.Conclusions: These data show differential postprandial 8-isoprostane F2α responses to high-fat meals containing EPA + DHA–rich fish oil compared with DHA-rich AO, but these differences were not associated with consistent effects on postprandial vascular function or lipemia. More detailed analyses of polyunsaturated fatty acid–derived lipid mediators are required to determine possible divergent functional effects of single meals rich in either DHA or EPA. This trial was registered at clinicaltrials.gov as NCT01618071.

Abstract 134: Short-Term, High-Dose Fish Oil Supplementation Increases the Production of Downstream n-3 Fatty Acid Metabolites in Patients With Peripheral Artery Disease

OBJECTIVES: Patients with peripheral artery disease (PAD) experience significant morbidity and mortality, at least partially related to vascular inflammation and endothelial dysfunction. The OMEGA-PAD I Trial (NCT01310270), a randomized, double-blinded, placebo-controlled trial addressed the hypothesis that short-duration, high-dose n-3 polyunsaturated fatty acids (n-3 PUFA) oral supplementation improves endothelial function (EF) and inflammation in subjects with PAD. METHODS: Eighty patients with stable, mild-severe claudication and ABI&lt;0.9 received 4.1gm of fish oil (FISH) vs placebo capsules (CTL) for 1 month. The primary endpoint was EF as measured by brachial artery flow-mediated vasodilation (FMD). Secondary endpoints included biomarkers of inflammation, generation of n-3 fatty acid-derived lipid metabolites, lipid profile and walking impairment questionnaires. RESULTS: The FISH and CTL group were no different with regards to age, baseline EF, inflammation and lipid profiles. Following treatment, there was a significant reduction in triglycerides (-34 ± 46, p=0.0001) and an improvement in HDL (+2 ± 6, p=0.03) in the FISH group. These changes were accompanied by an increase in the omega-3 index of 4 ± 1% (p&lt;0.00001). We observed a significant increase in the production of downstream metabolites of n-3 fatty acids including 18-, 15- and 5-hydroxy eicosapentaenoic acids and 4-hydroxy docosahexaenoic acid in the FISH group. n-3 PUFA led to a significant improvement in FMD in the FISH group (+0.7 ± 4.0%, p=0.04) and a non-significant improvement in the CTL (+0.6 ± 2.5, p=0.18) group. There were no significant differences between groups in pro-inflammatory markers or walking parameters post-treatment. CONCLUSIONS: High-dose, short-duration n-3 PUFA supplementation significantly improves the metabolo-lipidomic profile of patients with PAD. Longer studies are needed to assess the effects of n-3 PUFA on inflammation, vascular function, and clinical endpoints in patients with established PAD and to determine whether generation of n-3 fatty acid-derived bioactive lipid mediators is related to clinical outcomes.

Diversity and function of membrane glycerophospholipids generated by the remodeling pathway in mammalian cells

Cellular membranes are composed of numerous kinds of glycerophospholipids with different combinations of polar heads at the sn-3 position and acyl moieties at the sn-1 and sn-2 positions, respectively. The glycerophospholipid compositions of different cell types, organelles, and inner/outer plasma membrane leaflets are quite diverse. The acyl moieties of glycerophospholipids synthesized in the de novo pathway are subsequently remodeled by the action of phospholipases and lysophospholipid acyltransferases. This remodeling cycle contributes to the generation of membrane glycerophospholipid diversity and the production of lipid mediators such as fatty acid derivatives and lysophospholipids. Furthermore, specific glycerophospholipid transporters are also important to organize a unique glycerophospholipid composition in each organelle. Recent progress in this field contributes to understanding how and why membrane glycerophospholipid diversity is organized and maintained.