17-hydroxydocosahexaenoic Acid Research Articles

Iron and a mixture of DHA and EPA supplementation, alone and in combination, affect bioactive lipid signalling and morbidity of iron deficient South African school children in a two-by-two randomised controlled trial

We recently reported that iron supplementation increased respiratory morbidity in iron deficient South African children. This increase, however, was attenuated when iron was provided in combination with a mixture of DHA/EPA. To explore potential underlying mechanisms, we examined the effects of iron and DHA/EPA, alone and in combination, on plasma lipid-derived immune modulator concentrations and related gene expression in peripheral blood mononuclear cells (PBMC). DHA/EPA decreased inflammatory 12-hydroxyeicosatetraenoic acid and tended to increase anti-inflammatory and pro-resolving 17-hydroxydocosahexaenoic acid (17-HDHA), while iron decreased 17-HDHA. However, in combination with iron, the anti-inflammatory effect of DHA/EPA was maintained. These biochemical changes may explain the prevention of iron-induced respiratory morbidity that we observed when iron was supplemented in combination with DHA/EPA during the 8.5 month randomised controlled trial and might lead to a safer approach of delivering iron supplementation. The study was registered at clinicaltrials.gov as NCT01092377.

Gram scale synthesis of specialized pro-resolving mediator 17(S)-HDHA using lipoxygenase enhanced by water-soluble reducing agent TCEP

17(S)-Hydroxy docosahexaenoic acid (17(S)-HDHA) is a specialized pro-resolving mediator. The oxidation of docosahexaenoic acid (DHA) to 17(S)-HDHA using soybean lipoxygenase was accomplished in the presence of the reducing agent TCEP in high yield and high enantio excess. We demonstrated application of this strategy to the synthesis of other fatty acids and to gram scale synthesis of 17(S)-HDHA.

Oxylipins, endocannabinoids, and related compounds in human milk: Levels and effects of storage conditions

The presence of fatty acid derived oxylipins, endocannabinoids and related compounds in human milk may be of importance to the infant. Presently, clinically relevant protocols for storing and handling human milk that minimize error and variability in oxylipin and endocannabinoid concentrations are lacking. In this study, we compared the individual and combined effects of the following storage conditions on the stability of these fatty acid metabolites in human milk: state (fresh or frozen), storage temperature (4°C, −20°C or −80°C), and duration (1day, 1 week or 3 months). Thirteen endocannabinoids and related compounds, as well as 37 oxylipins were analyzed simultaneously by liquid chromatography coupled to tandem mass spectrometry. Twelve endocannabinoids and related compounds (2–111nM) and 31 oxylipins (1.2pM–1242nM) were detected, with highest levels being found for 2-arachidonoylglycerol and 17(R)hydroxydocosahexaenoic acid, respectively. The concentrations of most endocannabinoid-related compounds and oxylipins were dependent on storage condition, and especially storage at 4°C introduced significant variability. Our findings suggest that human milk samples should be analyzed immediately after, or within one day of collection (if stored at 4°C). Storage at −80°C is required for long-term preservation, and storage at −20°C is acceptable for no more than one week. These findings provide a protocol for investigating the oxylipin and endocannabinoid metabolome in human milk, useful for future milk-related clinical studies.

Specialized proresolving lipid mediators in humans with the metabolic syndrome after n–3 fatty acids and aspirin

The metabolic syndrome (MetS) is associated with a chronic low-grade inflammatory state and may be affected by the ability to resolve inflammation, which is an active process that involves specialized proresolving lipid mediators (SPMs) derived from n-3 (ω-3) fatty acids. We compared plasma concentrations of SPMs in men and women with features of the MetS and in healthy matched control subjects in response to intakes of n-3 fatty acids and aspirin. MetS volunteers (n = 22) and healthy, matched controls (n = 21) were studied in parallel for 4 wk. Both groups took n-3 fatty acids (2.4 g/d) for 4 wk with the addition of aspirin (300 mg/d) during the last 7 d. Blood was collected at baseline and at 3 and 4 wk. Plasma SPMs were measured with the use of liquid chromatography-tandem mass spectrometry and included 18-hydroxyeicosapentaenoic acid (18-HEPE), E-series resolvins, 17-hydroxydocosahexaenoic acid (17-HDHA), D-series resolvins, 14-hydroxydocosahexaenoic acid (14-HDHA), and maresin-1. Baseline SPMs did not differ between groups. There was an increase in the SPM precursors 18-HEPE, 17-HDHA, and 14-HDHA after n-3 fatty acid supplementation that was significantly attenuated in the MetS (P < 0.05). However, the E-series resolvins increased to a similar extent in the groups after n-3 fatty acid supplementation, and the D-series resolvins were not different from those at baseline. The addition of aspirin to n-3 fatty acids did not alter any SPMs in either group. Volunteers with MetS had reduced plasma concentrations of the precursors of the E- and D- series resolvins as well as of 14-HDHA in response to n-3 fatty acid supplementation. However, plasma E-series resolvins were increased to a similar extent after n-3 fatty acid supplementation in both groups, and the addition of aspirin to n-3 fatty acid supplementation did not alter any of the plasma SPMs in MetS and control subjects. Additional studies in the MetS are required to determine whether SPMs affect the ability to mount an appropriate response to infection. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN12610000708055.

Specialized proresolving mediators (SPMs) inhibit human B‐cell IgE production

Specialized proresolving mediators (SPMs) constitute a recently recognized class of bioactive molecules thatpromote the resolution of inflammation. We recently reported that the SPMs resolvin D1 (RvD1) and 17-hydroxydocosahexaenoic acid (17-HDHA) promote the differentiation of IgG-secreting B cells and enhance antibody-mediated immune responses. However, there is an important knowledge gap regarding whether or not SPMs regulate human B-cell IgE production, which is the key effector in diseases such as asthma and allergy. Therefore, we investigated whether a panel of diverse SPMs influences B-cell IgE production. An important finding was that 17-HDHA and RvD1 inhibit IgE production by human B cells and suppress the differentiation of naïve B cells into IgE-secreting cells by specifically blocking epsilon germline transcript. This effect is specific to human IgE, as the SPMs do not inhibit production of IgM and IgG and did not suppress other IL-4-upregulated genes. 17-HDHA and RvD1 act by stabilizing the transcriptional repressor B-cell lymphoma 6, which competes with STAT6 for binding at the epsilon germline transcript promoter. Overall, these new findings demonstrate that certain SPMs inhibit the differentiation of IgE-producing B cells, without being broadly immune suppressive, representing a novel class of potential therapeutics for IgE-driven diseases such as asthma and allergy.

Abstract 2803: Oral administration of an acid stable liposomal formulation of docosahexaenoic acid (DHA) delivers DHA and its LOX-metabolites to the circulation and the breast tissue of sprague dawley rats

Abstract We have shown that dietary ratios of omega-3 to omega-6 fatty acids that significantly inhibited chemically-induced mammary carcinogenesis in the rat were in excess of 10:1 suggesting that a particular omega-3 fatty acid or its metabolite may account for the chemopreventive effects of such high ratios. Docosahexaenoic acid (DHA; 22:6 n-3), a component in fish oil, has been shown to inhibit mammary cancer-induced by chemical carcinogens (7,12-dimethylbenz-[a]-anthracene and N-methyl-N-nitrosourea) in the rat. The Western Diet in humans, with a ratio of 1:15 omega-3:omega-6 fatty acids, is not sufficient to provide the levels of DHA required for cancer prevention. Furthermore, mammals can't synthesize this fatty acid. Previously, a liposomal formulation for DHA for intravenous administration has been developed, but this route of administration is not appropriate for chemoprevention. Oral delivery for long term is the preferred approach. Therefore, we hypothesize that the oral delivery of a liposomal formulation of DHA which is resistant to oxidation and low gastric pH will enhance its bioavailability in the circulation and the breast tissues, and thus enhance the chemopreventive efficacy. We have developed for the first time an acid stable liposomal delivery system of DHA; average size determined by Dynamic Light Scattering is approximately 135nm, while that of the ghost formulation is approximately 150nm. This size is ideal for oral administration and can cross the enterocytes of the intestine. In a pilot study a single dose of liposomal DHA(1.54mg DHA/rat) was orally administered to female Sprague Dawley rats 21 days of age; rats were sacrificed after 24 hours by CO2 asphyxiation and their plasma and various organs including the breast tissue were harvested. The amount of DHA in the plasma and breast tissue was determined by gas chromatography flame ionization detection. Approximately 3.4% of the dose was determined to be in the plasma, while levels of DHA that reached the breast tissue were at least 5-fold higher than those measured in plasma. Using LC-MS/MS we detected DHA and its metabolites, 14-hydroxy DHA and 17-hydroxy DHA, catalyzed by LOX enzymes in rat plasma. In the breast tissue 4-hydroxy DHA, 14-hydroxy DHA, 17-hydroxy DHA, and 20-hydroxy DHA were detected. In summary, we report for the first time the detection of DHA and its LOX-metabolites in the circulation and breast tissue following the oral administration of liposomal DHA, suggesting that our nanotechnology-based approach is a promising strategy for breast cancer prevention. (Support: Institutional Funding) Citation Format: Christine G. Skibinski, Arunangshu Das, Kun-Ming Chen, Neil Trushin, Bogdan Prokopczyk, Cesar Aliaga, Mark Kester, Andrea Manni, Karam El-Bayoumy. Oral administration of an acid stable liposomal formulation of docosahexaenoic acid (DHA) delivers DHA and its LOX-metabolites to the circulation and the breast tissue of sprague dawley rats. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2803. doi:10.1158/1538-7445.AM2015-2803

Effect of Different Omega-6/Omega-3 Polyunsaturated Fatty Acid Ratios on the Formation of Monohydroxylated Fatty Acids in THP-1 Derived Macrophages.

Omega-6 and omega-3 polyunsaturated fatty acids (n-6 and n-3 PUFA) can modulate inflammatory processes. In western diets, the content of n-6 PUFA is much higher than that of n-3 PUFA, which has been suggested to promote a pro-inflammatory phenotype. The aim of this study was to analyze the effect of modulating the n-6/n-3 PUFA ratio on the formation of monohydroxylated fatty acid (HO-FAs) derived from the n-6 PUFA arachidonic acid (AA) and the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in THP-1 macrophages by means of LC-MS. Lipid metabolites were measured in THP-1 macrophage cell pellets. The concentration of AA-derived hydroxyeicosatetraenoic acids (HETEs) was not significantly changed when incubated THP-1 macrophages in a high AA/(EPA+DHA) ratio of 19/1 vs. a low ratio AA/(EPA+DHA) of 1/1 (950.6 ± 110 ng/mg vs. 648.2 ± 92.4 ng/mg, p = 0.103). Correspondingly, the concentration of EPA-derived hydroxyeicosapentaenoic acids (HEPEs) and DHA-derived hydroxydocosahexaenoic acids (HDHAs) were significantly increased (63.9 ± 7.8 ng/mg vs. 434.4 ± 84.3 ng/mg, p = 0.012 and 84.9 ± 18.3 ng/mg vs. 439.4 ± 82.7 ng/mg, p = 0.014, respectively). Most notable was the strong increase of 18-hydroxyeicosapentaenoic acid (18-HEPE) formation in THP-1 macrophages, with levels of 170.9 ± 40.2 ng/mg protein in the high n-3 PUFA treated cells. Thus our data indicate that THP-1 macrophages prominently utilize EPA and DHA for monohydroxylated metabolite formation, in particular 18-HEPE, which has been shown to be released by macrophages to prevent pressure overload-induced maladaptive cardiac remodeling.

Effects of maternal n-3 fatty acid supplementation on placental cytokines, pro-resolving lipid mediators and their precursors.

The aim of this study was to determine whether supplementation with fish oil-derived n-3 polyunsaturated fatty acids (n-3 PUFA) during pregnancy modifies placental PUFA composition, the accumulation of specialised pro-resolving lipid mediators (SPMs, specifically resolvins (Rv), protectins (PD) and upstream precursors) and inflammatory gene expression. Placentas were collected from women (n=51) enrolled in a randomised, placebo controlled trial of n-3 PUFA supplementation from 20-week gestation. Lipids were extracted for fatty acid analysis and SPMs were quantitated by mass spectrometry. Gene expression was determined by qRT-PCR. Using multiple regression analysis, data were correlated for placental n-3 PUFA and SPM levels with PUFA levels in maternal and cord blood erythrocytes. Supplementation with n-3 PUFAs increased placental docosahexaenoic acid (DHA) levels, but not eicosapentaenoic acid (EPA) levels (P<0.05), and increased the levels of the SPM precursors 18-hydroxyeicosapentaenoic acid and 17-hydroxydocosahexaenoic acid (17-HDHA) by two- to threefold (P<0.0005). RvD1, 17R-RvD1, RvD2 and PD1 were detectable in all placentas, but concentrations were not significantly increased by n-3 PUFA supplementation. Placental DHA levels were positively associated with maternal and cord DHA levels (P<0.005), and with placental 17-HDHA concentrations (P<0.0001). Placental mRNA expression of PTGS2, IL1β, IL6 and IL10 was unaffected by n-3 PUFA supplementation, but TNFα expression was increased by 14-fold (P<0.05). We conclude that n-3 PUFA supplementation in pregnancy i) enhances placental accumulation of DHA and SPM precursors, ii) does not alter placental EPA levels, and iii) has no stimulatory effects on inflammatory gene expression. Further studies are required to ascertain the biological significance of SPMs in the placenta and the potential immunomodulatory effects of elevating placental SPM levels.

Chiral chromatography–tandem mass spectrometry applied to the determination of pro-resolving lipid mediators

Pro-resolving lipid mediators are a class of endogenously synthesized molecules derived from different fatty acids, such as arachidonic, docosahexaenoic or eicosapentaenoic acid, which are derived into four different product families: lipoxins, resolvins, maresins and protectins. For quantitation of these compounds, a sensitive, selective and robust liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous quantitation of lipoxin A4, 6-epi-lipoxin A4, lipoxin B4 and lipoxin A5, the D-series resolvins D1 and D2 as well as aspirin-triggered lipoxin A4 and resolvin D1, maresin and protectin and the pathway markers 17(S)-hydroxy-docosahexaenoic acid and 17(R)-hydroxy-docosahexaenoic acid in cell culture supernatants. For this purpose, a chiral column was connected in series with a reversed-phase column to achieve efficient analyte separation and high sensitivity. Sample pre-treatment included a fast and simple liquid–liquid extraction procedure. Limits of quantitation in the range of 0.1–0.5ng/mL cell culture media, absolute recoveries between 90 and 115%, intra- and interday precision of less than 13% and an accuracy of less than 11% were obtained. Stability of the samples after 60 days storage at −80°C, three freeze/thaw cycles and 4h at room temperature has been demonstrated for all analytes. Sample extracts can be stored at 7°C for 24h without degradation of the analytes. Deviations of less than 13% in the accuracy, evaluated in terms of relative error, were obtained. The suitability of the method has been demonstrated in cell culture supernatants of human polymorphonuclear leukocytes, stimulated with 15R-hydroxy-eicosatetraenoic acid and in cell culture media of human polymorphonuclear leukocytes co-incubated with human platelets. From all studied analytes, lipoxin A4 and 6-epi-lipoxin A4 were found in cell culture media under both incubation conditions, while 15-epi-lipoxin A4 was additionally detected in cell culture supernatants of polymorphonuclear leukocytes stimulated with 15R-hydroxy-eicosatetraenoic acid.

Vaccination with DHA-derived specialized proresolving mediators increases the antibody-mediated immune response against influenza virus (VAC2P.925)

Abstract Influenza viruses remain a critical global health concern. More efficacious vaccines are needed to protect against influenza virus, yet few adjuvants are approved for routine use. Specialized proresolving mediators (SPMs) are powerful endogenous bioactive lipid regulators of inflammation, with great clinical translational properties. We previously identified endogenous levels of the SPM resolvin D1, protectin D1 and 17-hydroxydocosahexaenoic acid (17-HDHA) in the mouse spleen. Here, we investigated the ability of 17-HDHA to enhance the adaptive immune response using a pre-clinical influenza vaccination mouse model. Our findings revealed that mice immunized with influenza H1N1-derived HA protein plus 17-HDHA increased antigen specific antibody titers. 17-HDHA increased the number of plasma cells and HA-specific antibody-secreting cells in the bone marrow, but it did not affect the frequency of GC B cells or Tfh cells in the draining lymph node. Importantly, the 17-HDHA-mediated increased antibody production was more protective against live pH1N1 influenza virus infection in mice. This is the first report on the immuno-stimulatory effects of omega-3-derived SPMs on the humoral immune response. These findings illustrate a previously unknown biological relation between proresolution signals and the adaptive immune system. In addition, 17-HDHA as well as other immuno-stimulatory SPM have the potential to be used as novel endogenous adjuvants.

Membrane lipid modifications and therapeutic effects mediated by hydroxydocosahexaenoic acid on Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative pathology with relevant unmet therapeutic needs. Both natural aging and AD have been associated with a significant decline in the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA), and accordingly, administration of DHA has been proposed as a possible treatment for this pathology. However, recent clinical trials in mild-to-moderately affected patients have been inconclusive regarding the real efficacy of DHA in halting this disease. Here, we show that the novel hydroxyl-derivative of DHA (2-hydroxydocosahexaenoic acid — OHDHA) has a strong therapeutic potential to treat AD. We demonstrate that OHDHA administration increases DHA levels in the brain of a transgenic mouse model of AD (5xFAD), as well as those of phosphatidylethanolamine (PE) species that carry long polyunsaturated fatty acids (PUFAs). In 5xFAD mice, administration of OHDHA induced lipid modifications that were paralleled with a reduction in amyloid-β (Αβ) accumulation and full recovery of cognitive scores. OHDHA administration also reduced Aβ levels in cellular models of AD, in association with alterations in the subcellular distribution of secretases and reduced Aβ-induced tau protein phosphorylation as well. Furthermore, OHDHA enhanced the survival of neuron-like differentiated cells exposed to different insults, such as oligomeric Aβ and NMDA-mediated neurotoxicity. These results were supported by model membrane studies in which incorporation of OHDHA into lipid-raft-like vesicles was shown to reduce the binding affinity of oligomeric and fibrillar Aβ to membranes. Finally, the OHDHA concentrations used here did not produce relevant toxicity in zebrafish embryos in vivo. In conclusion, we demonstrate the pleitropic effects of OHDHA that might prove beneficial to treat AD, which suggests that an upstream event, probably the modulation of the membrane lipid composition and structure, influences cellular homeostasis reversing the neurodegenerative process. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Inhibition of the HER2 pathway by n-3 polyunsaturated fatty acids prevents breast cancer in fat-1 transgenic mice

Overexpression of the tyrosine kinase receptor, ErbB2/HER2/Neu, occurs in 25-30% of invasive breast cancer (BC) with poor patient prognosis. Due to confounding factors, inconsistencies still remain regarding the protective effects of n-3 polyunsaturated fatty acids (PUFAs) on BC. We therefore evaluated whether fat-1 transgenic mice, endogenously synthesizing n-3 PUFAs from n-6 PUFAs, were protected against BC development, and we then aimed to study in vivo a mechanism potentially involved in such protection. E0771 BC cells were implanted into fat-1 and wild-type (WT) mice. After tumorigenesis examination, we analyzed the expression of proteins involved in the HER2 signaling pathway and lipidomic analyses were performed in tumor tissues and plasma. Our results showed that tumors totally disappeared by day 15 in fat-1 mice but continued to grow in WT mice. This prevention can be related in part to significant repression of the HER2/β-catenin signaling pathway and formation of significant levels of n-3 PUFA-derived bioactive mediators (particularly 15-hydroxyeicosapentaenoic acid, 17-hydroxydocosahexaenoic acid, and prostaglandin E3) in the tumors of fat-1 mice compared with WT mice. All together these data demonstrate an anti-BC effect of n-3 PUFAs through, at least in part, HER2 signaling pathway downregulation, and highlight the importance of gene-diet interactions in BC.

The Development of a Specific and Sensitive LC-MS-Based Method for the Detection and Quantification of Hydroperoxy- and Hydroxydocosahexaenoic Acids as a Tool for Lipidomic Analysis

Docosahexaenoic acid (DHA) is an n-3 polyunsaturated fatty acid that is highly enriched in the brain, and the oxidation products of DHA are present or increased during neurodegenerative disease progression. The characterization of the oxidation products of DHA is critical to understanding the roles that these products play in the development of such diseases. In this study, we developed a sensitive and specific analytical tool for the detection and quantification of twelve major DHA hydroperoxide (HpDoHE) and hydroxide (HDoHE) isomers (isomers at positions 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19 and 20) in biological systems. In this study, HpDoHE were synthesized by photooxidation, and the corresponding hydroxides were obtained by reduction with NaBH4. The isolated isomers were characterized by LC-MS/MS, and unique and specific fragment ions were chosen to construct a selected reaction monitoring (SRM) method for the targeted quantitative analysis of each HpDoHE and HDoHE isomer. The detection limits for the LC-MS/MS-SRM assay were 1−670 pg for HpDoHE and 0.5−8.5 pg for HDoHE injected onto a column. Using this method, it was possible to detect the basal levels of HDoHE isomers in both rat plasma and brain samples. Therefore, the developed LC-MS/MS-SRM can be used as an important tool to identify and quantify the hydro(pero)xy derivatives of DHA in biological system and may be helpful for the oxidative lipidomic studies.

Impaired Local Production of Proresolving Lipid Mediators in Obesity and 17-HDHA as a Potential Treatment for Obesity-Associated Inflammation

Obesity-induced chronic low-grade inflammation originates from adipose tissue and is crucial for obesity-driven metabolic deterioration, including insulin resistance and type 2 diabetes. Chronic inflammation may be a consequence of a failure to actively resolve inflammation and could result from a lack of local specialized proresolving lipid mediators (SPMs), such as resolvins and protectins, which derive from the n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We assessed obesity-induced changes of n-3–derived SPMs in adipose tissue and the effects of dietary EPA/DHA thereon. Moreover, we treated obese mice with SPM precursors and investigated the effects on inflammation and metabolic dysregulation. Obesity significantly decreased DHA-derived 17-hydroxydocosahexaenoic acid (17-HDHA, resolvin D1 precursor) and protectin D1 (PD1) levels in murine adipose tissue. Dietary EPA/DHA treatment restored endogenous biosynthesis of n-3–derived lipid mediators in obesity while attenuating adipose tissue inflammation and improving insulin sensitivity. Notably, 17-HDHA treatment reduced adipose tissue expression of inflammatory cytokines, increased adiponectin expression, and improved glucose tolerance parallel to insulin sensitivity in obese mice. These findings indicate that impaired biosynthesis of certain SPM and SPM precursors, including 17-HDHA and PD1, contributes to adipose tissue inflammation in obesity and suggest 17-HDHA as a novel treatment option for obesity-associated complications.

Acetylsalicylic Acid Reduces the Severity of Dextran Sodium Sulfate-Induced Colitis and Increases the Formation of Anti-Inflammatory Lipid Mediators

The role of non-steroidal anti-inflammatory drugs in inflammatory bowel disease is controversial, as they have been implicated in disease aggravation. Different from other cyclooxygenase inhibitors, acetylsalicylic acid (ASA) enhances the formation of anti-inflammatory and proresolution lipoxins derived from arachidonic acid as well as resolvins from omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA). In this study, we examined the effect of ASA on murine dextran sodium sulfate colitis. A mouse magnetic resonance imaging (MRI) protocol and post mortem assessment were used to assess disease severity, and lipid metabolites were measured using liquid chromatography-coupled tandem mass spectrometry. Decreased colitis activity was demonstrated by phenotype and MRI assessment in mice treated with ASA, and confirmed in postmortem analysis. Analysis of lipid mediators showed sustained formation of lipoxin A4 and an increase of DHA-derived 17-hydroxydocosahexaenoic acid (17-HDHA) after treatment with ASA. Furthermore, in vitro experiments in RAW264.7 murine macrophages demonstrated significantly increased phagocytosis activity after incubation with 17-HDHA, supporting its proresolution effect. These results show a protective effect of ASA in a murine colitis model and could give a rationale for a careful reassessment of ASA therapy in patients with inflammatory bowel disease and particularly ulcerative colitis, possibly combined with DHA supplementation.

Erratum to: Omega-6 docosapentaenoic acid-derived resolvins and 17-hydroxydocosahexaenoic acid modulate macrophage function and alleviate experimental colitis

Erratum to: Omega-6 docosapentaenoic acid-derived resolvins and 17-hydroxydocosahexaenoic acid modulate macrophage function and alleviate experimental colitis

Omega-6 docosapentaenoic acid-derived resolvins and 17-hydroxydocosahexaenoic acid modulate macrophage function and alleviate experimental colitis

Enzymatically oxygenated lipid products derived from omega-3 and omega-6 fatty acids play an important role in inflammation dampening. This study examined the anti-inflammatory effects of n-6 docosapentaenoic acid-derived (17S)-hydroxy-docosapentaenoic acid (17-HDPAn-6) and (10,17S)-dihydroxy-docosapentaenoic acid (10,17-HDPAn-6) as well as n-3 docosahexaenoic acid-derived 17(R/S)-hydroxy-docosahexaenoic acid (17-HDHA). The effects of 17-HDPAn-6, 10,17-HDPAn-6 or 17-HDHA on activity and M1/M2 polarization of murine macrophage cell line RAW 264.7 were examined by phagocytosis assay and real-time PCR. To assess anti-inflammatory effects in vivo, dextran sodium sulfate (DSS) colitis was induced in mice treated with 17-HDPAn-6, 10,17-HDPAn-6, 17-HDHA or NaCl. Our results show that 17-HDPAn-6, 10,17-HDPAn-6 and 17-HDHA increase phagocytosis in macrophages in vitro and promote polarization towards the anti-inflammatory M2 phenotype with decreased gene expression of TNF-α and inducible Nitric oxide synthase and increased expression of the chemokine IL-1 receptor antagonist and the Scavenger receptor Type A. Intraperitoneal treatment with 17-HDPAn-6, 10,17-HDPAn-6, or 17-HDHA alleviated DSS-colitis and significantly improved body weight loss, colon epithelial damage, and macrophage infiltration. These results suggest that DPAn-6-derived 17-HDPAn-6 and 10,17-HDPAn-6 as well as the DHA-derived 17-HDHA have inflammation-dampening and resolution-promoting effects that could be used to treat inflammatory conditions such as inflammatory bowel disease.

Essential fatty acids and lipid mediators. Endocannabinoids

In 1929 Burr and Burr discovered the essential fatty acids omega-6 and omega-3. Since then, researchers have shown a growing interest in polyunsaturated fatty acids (PUFA) as precursors of "lipid mediator" molecules, often with opposing effects, prostaglandins, prostacyclins, thromboxanes, leukotrienes, lipossines, resolvines, protectines, maresins that regulate immunity, platelet aggregation, inflammation, etc. They showed that the balance between omega-3 and omega-6 acids has a profound influence on all the body's inflammatory responses and a raised level of PUFA omega-3 in tissue correlate with a reduced incidence of degenerative cardiovascular disease, some mental illnesses such as depression, and neuro-degenerative diseases such as Alzheimer's. The CYP-catalyzed epoxidation and hydroxylation of arachidonic acid (AA) were established recently as the so-called third branch of AGE cascade. Cytochrome P450 (CYP) epoxygenases convert AA to four epoxyeicosatrienoic acid (EET) regioisomers, that produce vascular relaxation anti-inflammatory effects on blood vessels and in the kidney, promote angiogenesis, and protect ischemic myocardium and brain. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are accessible to CYP enzymes in the same way as AA. Metabolites derived from EPA include epoxye-icosatetraenoic acids (EETR) and hydroxyeicosapentaenoic acids (19- and 20-HEPE), whereas DHA include epoxydocosapentaenoic acids (EDPs) hydroxydocosahexaenoic acids (21- and 22-HDoHE). For many of the CYP isoforms, the n-3 PUFAs are the preferred substrates and the available data suggest that some of the vasculo- and cardioprotective effects attributed to dietary n-3 PUFAs may be mediated by CYP-dependent metabolites of EPA and DHA. From AA derives also endocannabinoids like anandamide (N-arachidonoylethanolamine) and 2-arachidonoylglycerol, capable of mimicking the pharmacological actions of the active principle of Cannabis sativa preparations such as hashish and marijuana (-)-Delta9-tetrahydrocannabinol. They act as true 'endogenous cannabinoids' by binding and functionally activating one or both cannabinoid receptor present on nervous and peripheral cell membranes. Enzymes that carry out anandamide oxidation are the same fatty acid oxygenases that are known to act on endogenous arachidonic acid namely, the members of the COX, LOX, and P450 families of enzymes. Recent advances in the biochemistry and pharmacology of the endocannabinoid system, also for its central and peripheral roles in regulating food intake, will offer the development of novel therapeutic agents.

Resolvins are potent analgesics for arthritic pain

Arthritis-associated inflammatory pain represents a serious medical problem worldwide. Current treatments for arthritic pain are not very effective and cause unwanted side effects. Resolvins, including the resolvin D and resolvin E series, are a family of novel endogenous lipid mediators derived from ω-3 polyunsaturated fatty acids and display potent anti-inflammatory and pro-resolution actions in animal models of inflammation. Emerging evidence also points to a potent anti-hyperalgesic role of resolvins in animal models of inflammatory pain. The study by Lima-Garcia et al. in this issue of the BJP demonstrated that systemic treatment with 17(R)-hydroxy-docosahexaenoic acid (17(R)HDoHE), the precursor of resolvin D series and its product, aspirin-triggered resolvin D1 (AT-RvD1), at very low doses (1 µg·kg(-1)), reduced inflammatory pain in an adjuvant-induced arthritis model. Particularly 17(R)HDoHE reduced joint stiffness but not paw and joint oedema. Given their potency and safety profile, resolvins may represent a new class of analgesics well suited to treating inflammatory pain associated with arthritis. LINKED ARTICLE This article is a commentary on Lima-Garcia et al., pp. 278-293 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2011.01345.x.

Omega-3 Fatty Acid-Derived Mediators 17(R)-Hydroxy Docosahexaenoic Acid, Aspirin-Triggered Resolvin D1 and Resolvin D2 Prevent Experimental Colitis in Mice

Resolvins of the D series are generated from docosahexaenoic acid, which are enriched in fish oils and are believed to exert beneficial roles on diverse inflammatory disorders, including inflammatory bowel disease (IBD). In this study, we investigated the anti-inflammatory effects of the aspirin-triggered resolvin D1 (AT-RvD1), its precursor (17(R)-hydroxy docosahexaenoic acid [17R-HDHA]) and resolvin D2 (RvD2) in dextran sulfate sodium (DSS)- or 2,4,6-trinitrobenzene sulfonic acid-induced colitis. Our results showed that the systemic treatment with AT-RvD1, RvD2, or 17R-HDHA in a nanogram range greatly improved disease activity index, body weight loss, colonic damage, and polymorphonuclear infiltration in both colitis experimental models. Moreover, these treatments reduced colonic cytokine levels for TNF-α, IL-1β, MIP-2, and CXCL1/KC, as well as mRNA expression of NF-κB and the adhesion molecules VCAM-1, ICAM-1, and LFA-1. Furthermore, AT-RvD1, but not RvD2 or 17R-HDHA, depended on lipoxin A4 receptor (ALX) activation to inhibit IL-6, MCP-1, IFN-γ, and TNF-α levels in bone marrow-derived macrophages stimulated with LPS. Similarly, ALX blockade reversed the beneficial effects of AT-RvD1 in DSS-induced colitis. To our knowledge, our findings showed for the first time the anti-inflammatory effects of resolvins of the D series and precursor 17R-HDHA in preventing experimental colitis. We also demonstrated the relevant role exerted by ALX activation on proresolving action of AT-RvD1. Moreover, AT-RvD1 showed a higher potency than 17R-HDHA and RvD2 in preventing DSS-induced colitis. The results suggest that these lipid mediators possess a greater efficacy when compared with other currently used IBD therapies, such as monoclonal anti-TNF, and have the potential to be used for treating IBD.