Insight into the contribution of isoprostanoids to the health effects of omega 3 PUFAs.

Omega 3 polyunsaturated fatty acids have been reported to confer beneficial health effects notably in the field of cardiovascular and inflammatory diseases. The current knowledge suggests a significant portion of the effects of omega 3 polyunsaturated fatty acids are mediated by their oxygenated metabolites. This review attempts to cover the current literature about the contribution of specific omega 3 oxygenated metabolites, namely omega 3 isoprostanoids, which are produced through free-radical mediated oxidation. A special emphasis has been given to the most biologically relevant omega 3 polyunsaturated fatty acids namely the α-linolenic, eicosapentaenoic and docosahexaenoic acids. The review includes a comprehensive description of the biosynthetic pathways, a summary of studies related to the biological significance of omega 3 isoprostanoids as well as a critical description of analytical development in the field of omega 3 isoprostanoids profiling in biological samples.

Reduced production of isoprostanes by peri-pancreatic adipose tissue from Zucker fa/fa rats as a new mechanism for ß-cell compensation in insulin resistance and obesity.

During early stages of type 2 diabetes, named prediabetes, pancreatic ß-cells compensate for insulin resistance through increased insulin secretion in order to maintain normoglycemia. Obesity leads to the development of ectopic fat deposits, among which peri-pancreatic white adipose tissue (pWAT) can communicate with ß-cells through soluble mediators. Thus we investigated whether pWAT produced oxygenated lipids, namely isoprostanes and neuroprostanes and whether they can influence ß-cell function in obesity. In the Zucker fa/fa rat model, pWAT and epididymal white adipose tissue (eWAT) displayed different inflammatory profiles. In obese rats, pWAT, but not eWAT, released less amounts of 5-F2t-isoprostanes, 15-F2t-isoprostanes, 4-F4t-neuroprostanes and 10-F4t-neuroprostane compared to lean animals. These differences could be explained by a greater induction of antioxidant defenses enzymes such as SOD-1, SOD-2, and catalase in pWAT of obese animals compared to eWAT. In addition, sPLA2 IIA, involved in the release of isoprostanoids from cellular membranes, was decreased in pWAT of obese animals, but not in eWAT, and may also account for the reduced release of oxidized lipids by this tissue. At a functional level, 15-F2t-isoprostane epimers, but not 5-F2t-isoprostanes, were able to decrease glucose-induced insulin secretion in pancreatic islets from Wistar rats. This effect appeared to be mediated through activation of the thromboxane A2 receptor and reduction of cAMP signaling in pancreatic islets. In conclusion, through the removal of an inhibitory tone exerted by isoprostanes, we have shown, for the first time, a new mechanism allowing ß-cells to compensate for insulin resistance in obesity that is linked to a biocommunication between adipose tissue and ß-cells.

Long chain omega-3 fatty acids and their oxidized metabolites are associated with reduced prostate tumor growth.

INTRODUCTION: Cancer has been associated with increased oxidative stress and deregulation of bioactive oxylipins derived from long-chain polyunsaturated fatty acids (LC-PUFA) like arachidonic acid (AA). There is a debate whether ω-3 LC-PUFA could promote or prevent prostate tumor growth through immune modulation and reduction of oxidative stress. Our aim was to study the association between enzymatically or non-enzymatically produced oxidized-LC-PUFA metabolites and tumor growth in an immune-competent eugonadal and castrated C57BL/6 male mice injected with TRAMP-C2 prostate tumor cells, fed with ω-3 or ω-6 LC-PUFA-rich diets. MATERIALS AND METHODS: Tumor fatty acids were profiled by gas chromatography and 26 metabolites derived from either AA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were assessed by liquid chromatography-mass spectrometry. RESULTS: The enriched ω-3 diet did not reduce oxidative stress overall in tumors but favored the formation of ω-3 rather than ω-6 derived isoprostanoids. We discovered that EPA and its oxidized-derivatives like F3-isoprostanes and prostaglandin (PG)F3α, were inversely correlated with tumor volume (spearman correlations and T-test, p<0.05). In contrast, F2-isoprostanes, adrenic acid, docosapentaenoic acid (DPAω-6) and PGE2 were positively correlated with tumor volume. Interestingly, F4-neuroprostanes, PGD2, PGF2α, and thromboxane were specifically increased in TRAMP-C2 tumors of castrated mice compared to those of eugonadal mice. DISCUSSION: Decreasing tumor growth under ω-3 diet could be attributed in part to increased levels of EPA and its oxidized-derivatives, a reduced level of pro-angiogenic PGE2 and increased levels of F4-neuroprostanes and resolvins content in tumors, suspected of having anti-proliferative and anti-inflammatory effects.

Tissue Antioxidant Status and Lipid Peroxidation Are Related to Dietary Intake of n-3 Polyunsaturated Acids: A Rabbit Model.

Polyunsaturated fatty acid (PUFA) metabolism and tissue distribution is modulated by the oxidation of these molecules. This research aimed to investigate the implication of dietary n-3 PUFA supplementation (precursor and long-chain PUFA) on the PUFA profile and oxidative status of the liver, testis, and brain of adult rabbit bucks. Twenty New Zealand White rabbit bucks were divided into four experimental groups (n = 5 per group) and were fed different diets for 110 days: control (CNT), standard diet containing 50 mg/kg alpha-tocopheryl acetate (vitamin E); CNT+, standard diet + 200 mg/kg vitamin E; FLAX, standard diet + 10% flaxseed + 200 mg/kg vitamin E; or FISH, standard diet + 3.5% fish oil + 200 mg/kg vitamin E. Antioxidants (enzymatic and non-enzymatic), oxidative status (malondialdehyde and isoprostanoids), and n-3 and n-6 PUFAs of tissues were analysed. A chain mechanism of oxidant/antioxidant molecules, which largely depended on the particular PUFA composition, was delineated in the different organs. The liver showed an oxidant/antioxidant profile and lipid pathways widely modulated by PUFA and vitamin E administration; on the other hand, the testis' oxidative profile rather than its lipid profile seemed to be particularly affected, an outcome opposite to that of the brain (modulation operated by dietary PUFA).

Decreased Fatty Acid Transporter FABP1 and Increased Isoprostanes and Neuroprostanes in the Human Term Placenta: Implications for Inflammation and Birth Weight in Maternal Pre-Gestational Obesity.

The rise in prevalence of obesity in women of reproductive age in developed and developing countries might propagate intergenerational cycles of detrimental effects on metabolic health. Placental lipid metabolism is disrupted by maternal obesity, which possibly affects the life-long health of the offspring. Here, we investigated placental lipid metabolism in women with pre-gestational obesity as a sole pregnancy complication and compared it to placental responses of lean women. Open profile and targeted lipidomics were used to assess placental lipids and oxidised products of docosahexaenoic (DHA) and arachidonic acid (AA), respectively, neuroprostanes and isoprostanes. Despite no overall signs of lipid accumulation, DHA and AA levels in placentas from obese women were, respectively, 2.2 and 2.5 times higher than those from lean women. Additionally, a 2-fold increase in DHA-derived neuroprostanes and a 1.7-fold increase in AA-derived isoprostanes were seen in the obese group. These changes correlated with a 70% decrease in placental FABP1 protein. Multivariate analyses suggested that neuroprostanes and isoprostanes are associated with maternal and placental inflammation and with birth weight. These results might shed light on the molecular mechanisms associated with altered placental fatty acid metabolism in maternal pre-gestational obesity, placing these oxidised fatty acids as novel mediators of placental function.

Oxidative stress and antioxidant response in rainbow trout fry exposed to acute hypoxia is affected by selenium nutrition of parents and during first exogenous feeding.

Selenium (Se) deficiency is a problem widely encountered in humans and terrestrial livestock production with increasing attention also in aquaculture. Se supports the antioxidant system, which becomes especially important during stressful conditions. In the present study, the effect of Se-supplementation in broodstock and fry diets on the performance and antioxidant metabolism of rainbow trout fry under acute hypoxia was investigated. Rainbow trout broodstock were fed plant-ingredient based diets either without any Se-supplementation (Se level: 0.3 mg/kg) or supplemented with Se supplied as sodium selenite or as hydroxy-selenomethionine (Se level: 0.6 mg/kg respectively) for 6 months prior to spawning. The progenies were subdivided into three triplicate feeding groups and fed diets with similar Se levels compared to the parental diets, resulting in a 3x3 factorial design. After 11 weeks of feeding, the fry were either sampled or subjected to a hypoxic stress challenge. One hundred fish were transferred to tanks containing water with a low oxygen level (1.7 ± 0.2 ppm) and monitored closely for 30 min. When a fish started to faint it was recorded and transferred back to normoxic water. Direct fry feeding of the hydroxy-selenomethionine supplemented diet improved the resistance towards the hypoxic stress. On the contrary, fry originating from parents fed Se-supplemented diets showed a lower stress resistance compared to fry originating from parents fed the control diet. Fry subjected to hypoxia showed elevated oxidative stress with reduced glutathione (GSH) levels and increased isoprostanes (IsoP) and phytoprostanes (PhytoP) levels produced by lipid peroxidation of polyunsaturated fatty acids (PUFA), arachidonic and α-linolenic acids respectively. Increased mRNA expression of transcription factors (nrf2, nfκb, keap1X2) and decreased mRNA expression of antioxidant enzymes (trxr, sod, gstπ) indicated a transcriptional regulation of the antioxidant response. In stressed fry, the mRNA expression of several antioxidant genes including gr, msr and gstπ was found to be higher when fed the control diet compared to the sodium selenite treatment, with a contrary effect for parental and direct Se nutrition on gpx. The long-term parental effect becomes of greater importance in stressed fry, where more than half of the genes were significantly higher expressed in the control compared to the selenite supplemented group.

Isoprostanoid Profiling of Marine Microalgae.

Algae result from a complex evolutionary history that shapes their metabolic network. For example, these organisms can synthesize different polyunsaturated fatty acids, such as those found in land plants and oily fish. Due to the presence of numerous double-bonds, such molecules can be oxidized nonenzymatically, and this results in the biosynthesis of high-value bioactive metabolites named isoprostanoids. So far, there have been only a few studies reporting isoprostanoid productions in algae. To fill this gap, the current investigation aimed at profiling isoprostanoids by liquid chromatography -mass spectrometry/mass spectrometry (LC-MS/MS) in four marine microalgae. A good correlation was observed between the most abundant polyunsaturated fatty acids (PUFAs) produced by the investigated microalgal species and their isoprostanoid profiles. No significant variations in the content of oxidized derivatives were observed for Rhodomonas salina and Chaetoceros gracilis under copper stress, whereas increases in the production of C18-, C20- and C22-derived isoprostanoids were monitored in Tisochrysis lutea and Phaeodactylum tricornutum. In the presence of hydrogen peroxide, no significant changes were observed for C. gracilis and for T. lutea, while variations were monitored for the other two algae. This study paves the way to further studying the physiological roles of isoprostanoids in marine microalgae and exploring these organisms as bioresources for isoprostanoid production.

Chemical Compositional Changes in Over-Oxidized Fish Oils.

A recent study has reported that the administration during gestation of a highly rancid hoki liver oil, obtained by oxidation through sustained exposure to oxygen gas and incident light for 30 days, causes newborn mortality in rats. This effect was attributed to lipid hydroperoxides formed in the omega-3 long-chain polyunsaturated fatty acid-rich oil, while other chemical changes in the damaged oil were overlooked. In the present study, the oxidation condition employed to damage the hoki liver oil was replicated, and the extreme rancidity was confirmed. A detailed analysis of temporal chemical changes resulting from the sustained oxidative challenge involved measures of eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) omega-3 oil oxidative quality (peroxide value, para-anisidine value, total oxidation number, acid value, oligomers, antioxidant content, and induction time) as well as changes in fatty acid content, volatiles, isoprostanoids, and oxysterols. The chemical description was extended to refined anchovy oil, which is a more representative ingredient oil used in omega-3 finished products. The present study also analyzed the effects of a different oxidation method involving thermal exposure in the dark in contact with air, which is an oxidation condition that is more relevant to retail products. The two oils had different susceptibility to the oxidation conditions, resulting in distinct chemical oxidation signatures that were determined primarily by antioxidant protection as well as specific methodological aspects of the applied oxidative conditions. Unique isoprostanoids and oxysterols were formed in the over-oxidized fish oils, which are discussed in light of their potential biological activities.

Micro-extraction by packed sorbent combined with UHPLC-ESI-MS/MS for the determination of prostanoids and isoprostanoids in dried blood spots.

This work presents a reliable analytical procedure combining micro-extraction by packed sorbent (MEPS) and ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometry to determine 8-iso prostaglandin F2α, 8-iso prostaglandin E2 and prostaglandin E2 in dried blood spots (DBSs). To reach this goal, we optimized a fast semi-automated MEPS procedure for the clean-up and pre-concentration of the analytes extracted from a single DBS (50 µL) by a 70:30 v/v methanol:water mixture. Limits of detection of about 20 pg mL-1, satisfactory recoveries (90-110%) and very good intra- and inter-day precisions (RSD ≤10%) were obtained for all the analytes. The innovative addition of internal standards on the filter paper before DBS sampling allowed to compensate changes in the amount of analyte during storage. Since prostanoids and isoprostanoids are biomarkers involved in the pathogenesis and progression of many diseases (e.g. ductal patency, diabetic nephropathy, and acute lung injury), our analytical method offers interesting diagnostic and prognostic opportunities in the medical field. The present method is currently used for the analysis of such biomarkers in DBSs from preterm newborns collected in the clinical setting.

Long-Term Measures of Dyslipidemia, Inflammation, and Oxidative Stress in Rats Fed a High-Fat/High-Fructose Diet.

Inflammation and oxidative stress are thought to be involved in, or associated with, the development of obesity, dyslipidemia, hepatic steatosis, and insulin resistance. This work was designed to determine the evolution of inflammation and oxidative stress during onset and progression of hepatic steatosis and glucose intolerance. Seventy-five male Wistar rats were divided to control and high-fat high-fructose (HFHFr) groups. A subgroup of each group was sacrificed at 4, 8, 12, 16, and 20 weeks. HFHFr-fed rats exhibited overweight, glucose intolerance, and hepatic steatosis with increased contents of hepatic diacylglycerols and ceramides. The HFHFr diet increased hepatic interleukin 6 (IL-6) protein and adipose tissue CCL5 gene expression and hepatic nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity but not mitochondrial reactive oxygen species (ROS) production. The HFHFr diet decreased plasma and liver levels of isoprostanoid metabolites as well as plasma thiobarbituric acid-reactive substance (TBARS) levels. Hepatic glutathione content was decreased with a moderate decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) with the HFHFr diet. Overall, HFHFr diet led to hepatic lipid accumulation and glucose intolerance, which were accompanied by only moderate inflammation and oxidative stress. Most of these changes occurred at the same time and as early as 8 or 12 weeks of diet treatment. This implies that oxidative stress may be the result, not the cause, of these metabolic alterations, and suggests that marked hepatic oxidative stress should probably occur at the end of the steatotic stage to result in frank insulin resistance and steatohepatitis. These findings need to be further evaluated in other animal species as well as in human studies.

Isoprostanoids quantitative profiling of marine red and brown macroalgae.

With the increasing demand for direct human and animal consumption seaweed farming is rapidly expanding worldwide. Macroalgae have colonized aquatic environments in which they are submitted to frequent changes in biotic and abiotic factors that can trigger oxidative stress (OS). Considering that isoprostanoid derivatives may constitute the most relevant OS biomarkers, we were interested to establish their profile in two red and four brown macroalgae. Seven phytoprostanes, three phytofuranes, and four isoprostanes were quantified through a new micro-LC-MS/MS method. The isoprostanoid contents vary greatly among all the samples, the ent-16(RS)-9-epi-ST-Δ14-10-PhytoF and the sum of 5-F2t-IsoP and 5-epi-5F2t-IsoP being the major compounds for most of the macroalgae studied. We further quantified these isoprostanoids in macroalgae submitted to heavy metal (copper) exposure. In most of the cases, their concentrations increased after 24 h of copper stress corroborating the original hypothesis. One exception is the decrease of ent-9-L1-PhytoP content in L. digitata.

Prenatal exposure to the contaminant perfluorooctane sulfonate elevates lipid peroxidation during mouse fetal development but not in the pregnant dam.

Perfluorooctane sulfonate (PFOS), a member of the perfluorinated chemical family, has been convincingly demonstrated to affect lipid metabolism in animals and humans and readily crosses the placenta to exert its effects on the developing fetuses. While its exact mechanism is still not clear, PFOS exposure has long been suggested to exert its toxicity via oxidative stress and/or altered gene expression. Levels of PFOS and malondialdehyde in various organs and cell cultures have been widely determined as general indicators of non-specific lipid peroxidation after PFOS exposure. In this study, the oxidation of precise polyunsaturated fatty acids and their metabolites, derived from enzymatic and non-enzymatic pathways was determined following PFOS exposure in both adult and maternal/fetal mice. CD-1 mice were exposed to 3 mg/kg body weight/day of PFOS in corn oil by oral gavage until late gestation (GD17). We demonstrated that lipid peroxidation was particularly and exclusively affected in fetuses exposed to PFOS, but this was not the case in the maternal mice, where limited effects were observed in the enzymatic oxidation pathway. In this study, we demonstrated that PFOS-induced lipid peroxidation might have a greater impact in free radical generation in fetuses than in dams and could be responsible for affecting fetal development. In addition, antioxidant enzymes, such as superoxide dismutase and catalase, appeared to maintain oxidative stress homeostasis partially in adult mice exposed to PFOS. Taken together, our results might elucidate the mechanism of how PFOS induces oxidative stress in vivo.