Valvular Prostaglandins Are Elevated in Severe Human Aortic Valve Stenosis.

BACKGROUND: Aortic valve stenosis (AVS) is the most common valvular disease in the developed world. AVS involves the progressive fibrocalcific remodeling of the aortic valve (AV), which impairs function and can ultimately lead to heart failure. Due to gaps in our understanding of the underlying mechanisms of AVS, there are no pharmacological treatments or dietary interventions known to slow AVS progression. Recent studies have begun to suggest oxylipins-a class of bioactive lipids-may be dysregulated in the valves of patients with AVS. METHODS: We utilized high-performance liquid chromatography-tandem mass spectrometry to conduct a targeted oxylipin analysis on human AV tissue and plasma from a cohort of 110 patients undergoing AV surgery. RESULTS: We identified 36 oxylipins in human AV tissue with all showing significant increase in patients with severe AVS. A multivariate model including patient characteristics and valvular oxylipins identified the arachidonic acid-COX (cyclooxygenase) pathway-derived prostanoids to be the most associated with AVS severity. Plasma oxylipin levels were measured in a subset of AV surgery patients and compared with a control group of healthy participants, showing distinct oxylipin profiles between control and disease. CONCLUSIONS: Our comprehensive analysis of oxylipins in the human AV identified the inflammatory and osteogenic regulating prostanoids to be positively correlated with AVS severity. This elucidation of prostanoid dysregulation warrants further research into COX inhibition to mitigate AVS.

Species-specific oxylipins and the effects of ontogeny and predation on their emission from freshwater snails.

Chemical cues play important roles in mediating ecological interactions. Oxylipins, oxygenated metabolites of fatty acids, are one signalling molecule type that influences the physiology and function of species, suggesting their broader significance in chemical communication within aquatic systems. Yet, our current understanding of their function is restricted taxonomically and contextually making it difficult to infer their ecological significance. Snails and leeches are ubiquitous in freshwater ecosystems worldwide, yet little is known about their oxylipin profiles and the factors that cause their profiles to change. As snails and leeches differ taxonomically and represent different trophic groups, we postulated oxylipin profile differences. For snails, we hypothesized that ontogeny (non-reproductive vs reproductive) and predation (non-infested vs leech-infested) would affect oxylipin profiles. Oxylipins were characterized from water conditioned with the snail Planorbella duryi and leech Helobdella lineata, and included three treatment types (snails, leeches, and leech-infested snails) with the snails consisting of three size classes: small (5-6 mm, non-reproductive) and medium and large (13-14 and 19-20 mm, reproductive). The two species differed in the composition of their oxylipin profiles both in diversity and amounts. Further, ontogeny and predation affected the diversity of oxylipins emitted by snails. Our experimental profiles of oxylipins show that chemical cues within freshwater systems vary depending upon the species emitting the signals, the developmental stage of the species, as well as from ecological interactions such as predation. We also identified some candidates, like 9-HETE and PGE2, that could be explored more directly for their physiological and ecological roles in freshwater systems.

Lipoxygenase-derived oxylipins are enriched in anti-citrullinated protein antibody (ACPA)-positive individuals at risk for developing rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is typically preceded by an extended preclinical period where circulating autoantibodies, particularly anti-citrullinated protein antibodies (ACPA), are detectable in the absence of clinical arthritis. Increased dietary intake of anti-inflammatory omega-3 (ω3) polyunsaturated fatty acids (PUFA) has been shown to be associated with a lower the risk of developing incident RA in large epidemiological studies. It is currently not known how changes in fatty acid (FA) metabolism may impact on the progression towards RA in at-risk individuals. To begin to address this question, we profiled serum FAs and oxylipins in an established cohort of at-risk ACPA-positive first-degree relatives (FDR) of RA patients (N = 31), some of whom developed RA (N = 4), and compared their profile to ACPA-negative FDR from the same population (N = 10). METHODS: Gas chromatography (GC) was used for FA quantitation. Oxylipins were extracted and quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). RESULTS: Although we did not detect any meaningful differences in overall FA content between ACPA + and ACPA - FDR, the levels of oxylipins derived from FA metabolism demonstrated significant differences between the two groups, with the ACPA + group demonstrating enrichment in circulating arachidonic acid- and eicosapentaenoic acid-derived molecules. Compared with the ACPA - FDR group, the ACPA + FDR, including those who progressed into inflammatory arthritis, displayed higher levels of LOX-derived oxylipins. CONCLUSION: ACPA seropositivity in otherwise unaffected individuals at-risk for developing future RA based on family history (FDR) is associated with alterations in the serum oxylipin profile that suggests dysregulated LOX activity.

The Effect of Increasing Concentrations of Omega-3 Fatty Acids from either Flaxseed Oil or Preformed Docosahexaenoic Acid on Fatty Acid Composition, Plasma Oxylipin, and Immune Response of Laying Hens.

BACKGROUND: There is a lack of nutrition guidelines for the feeding of omega-3 polyunsaturated fatty acids (PUFA) to laying hens. Knowledge as to whether the type and concentrations of α-linolenic acid (ALA) and/or docosahexaenoic acid (DHA) in the diet can make a difference to the birds' immune responses when subjected to a lipopolysaccharide (LPS) challenge is limited. OBJECTIVES: The study was designed to determine the potential nutritional and health benefits to laying hens when receiving dietary omega-3 PUFA from either ALA or DHA. METHODS: A total of 80 Lohmann LSL-Classic (white egg layer, 20 wk old) were randomly assigned to 1 of 8 treatment diets (10 hens/treatment), provided 0.2%, 0.4%, 0.6%, or 0.8% of total dietary omega-3 PUFA, provided as either ALA-rich flaxseed oil or DHA-enriched algal biomass. After an 8-wk feeding period, the birds were challenged with Escherichia coli-derived LPS (8 mg/kg; i.v. injection), with terminal sample collection 4 h after challenge. Egg yolk, plasma, liver, and spleen samples were collected for subsequent analyses. RESULTS: Increasing dietary omega-3 supplementation yielded predictable responses in egg yolk, plasma, and liver fatty acid concentrations. Dietary intake of ALA contributed mainly to ALA-derived oxylipins. Meanwhile, eicosapentaenoic acid- and DHA-derived oxylipins were primarily influenced by DHA dietary intake. LPS increased the concentrations of almost all the omega-6 PUFA-, ALA-, and DHA-derived oxylipins in plasma and decreased hepatic mRNA expression of COX-2 and 5-LOX (P < 0.001) involved in the biosynthesis of oxylipins. LPS also increased mRNA expression of proinflammatory cytokine IFN-γ and receptor TLR-4 (P < 0.001) in the spleen. CONCLUSIONS: These results revealed that dietary intake of ALA and DHA had unique impacts on fatty acid deposition and their derived oxylipins and inflammatory responses under the administration of LPS in laying hens.

Nutrition and immunity: perspectives on key issues and next steps.

In January 2022, a group of experts came together to discuss current perspectives and future directions in nutritional immunology as part of a symposium organized by the Canadian Nutrition Society. Objectives included (1) creating an understanding of the complex interplay between diet and the immune system from infants through to older adults, (2) illustrating the role of micronutrients that are vital to the immune system, (3) learning about current research comparing the impact of various dietary patterns and novel approaches to reduce inflammation, autoimmune conditions, allergies, and infections, and (4) discussing select dietary recommendations aimed at improving disease-specific immune function. The aims of this review are to summarize the symposium and to identify key areas of research that require additional exploration to better understand the dynamic relationship between nutrition and immune function.

Factors affecting variability in free oxylipins in mammalian tissues.

PURPOSE OF THE REVIEW: Along with the growing interest in oxylipins is an increasing awareness of multiple sources of variability in oxylipin data. This review summarizes recent findings that highlight the experimental and biological sources of variation in free oxylipins. RECENT FINDINGS: Experimental factors that affect oxylipin variability include different methods of euthanasia, postmortem changes, cell culture reagents, tissue processing conditions and timing, storage losses, freeze-thaw cycles, sample preparation techniques, ion suppression, matrix effects, use and availability of oxylipin standards, and postanalysis procedures. Biological factors include dietary lipids, fasting, supplemental selenium, vitamin A deficiency, dietary antioxidants and the microbiome. Overt, but also more subtle differences in health affect oxylipin levels, including during resolution of inflammation and long-term recovery from disease. Sex, genetic variation, exposure to air pollution and chemicals found in food packaging and household and personal care products, as well as many pharmaceuticals used to treat health conditions also affect oxylipin levels. SUMMARY: Experimental sources of oxylipin variability can be minimized with proper analytical procedures and protocol standardization. Fully characterizing study parameters will help delineate biological factors of variability, which are rich sources of information that can be used to probe oxylipin mechanisms of action and to investigate their roles in health.

Phospholipase A2 enzymes differently impact PUFA release and oxylipin formation ex vivo in rat hearts.

Phospholipase A2 (PLA2) enzymes cleave cell membrane phospholipids and release polyunsaturated fatty acids (PUFA), which can be converted into oxylipins. However, little is known about PLA2 preference for PUFA, and even less is known about how this further impacts oxylipin formation. Therefore, we investigated the role of different PLA2 groups in PUFA release and oxylipin formation in rat hearts. Sprague-Dawley rat heart homogenates were incubated without or with varespladib (VAR), methyl arachidonyl fluorophosphonate (MAFP) or EDTA. Free PUFA and oxylipins were determined by HPLC-MS/MS, and isoform expressions by RT-qPCR. Inhibition of sPLA2 IIA and/or V by VAR reduced the release of ARA and DHA, but only DHA oxylipins were inhibited. MAFP reduced the release of ARA, DHA, ALA, and EPA, and the formation of ARA, LA, DGLA, DHA, ALA, and EPA oxylipins. Interestingly, cyclooxygenase and 12-lipoxygenase oxylipins were not inhibited. mRNA expression levels of sPLA2 and iPLA2 isoforms were highest whereas levels of cPLA2 were low, consistent with activity. In conclusion, sPLA2 enzymes lead to the formation of DHA oxylipins, while iPLA2 is likely responsible for the formation of most other oxylipins in healthy rat hearts. Oxylipin formation cannot be implied from PUFA release, thus, both should be evaluated in PLA2 activity studies.

Distinct effects of α-linolenic acid and docosahexaenoic acid on the expression of genes related to cholesterol metabolism and the response to infection in THP-1 monocytes and immune cells of obese humans.

BACKGROUND: Monocytes play a large role in chronic inflammatory conditions such as obesity, atherosclerosis and infection. Marine-derived omega-3 fatty acids such as docosahexaenoic acid (DHA) beneficially alter immune function and attenuate chronic inflammation in part by modifying gene expression. Comparisons with plant-derived omega-3 α-linolenic acid (ALA) on immune cell gene expression and function are limited. METHODS: Transcriptome analysis was performed on THP-1 human monocytes treated with ALA, DHA or vehicle for 48 hr using fold change analysis, principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), variable importance analysis (VIP), and ingenuity pathway analysis (IPA). Candidate genes were validated by qPCR. Functional assays evaluated the transcriptomic predictions. Expression of candidate transcripts identified in THP-1 cells were examined in PBMC from clinical trial (OXBIO; NCT03583281) participants consuming ALA- or DHA-rich oil supplements. FINDINGS: ALA and DHA-treated monocytes presented distinct transcriptomic profiles as per VIP and PLS-DA. Both fatty acids were predicted to reduce cellular cholesterol content, while ALA would uniquely increase response to infection and chemotactic signals. Functional assays revealed ALA and DHA decreased cholesterol content. DHA significantly decreased the response to infection and chemotaxis, but ALA had no effect. Candidate transcripts responded similarly in PBMC from n-3 PUFA supplemented women with obesity. CONCLUSION: ALA and DHA differentially alter the transcription profiles and functions associated with the response to infection, chemotaxis, and cholesterol metabolism in mononuclear immune cells. Thus, they may uniquely affect related disease processes contributing to obesity, atherosclerosis, and the response to infection.

Impact of Reperfusion on Plasma Oxylipins in ST-Segment Elevation Myocardial Infarction.

ST-segment elevation myocardial infarction (STEMI) occurs as a result of acute occlusion of the coronary artery. Despite successful reperfusion using primary percutaneous coronary intervention (PPCI), a large percentage of myocardial cells die after reperfusion, which is recognized as ischemia/reperfusion injury (I/R). There are rapid changes in plasma lipidome during myocardial reperfusion injury. However, the impact of coronary artery reperfusion on plasma oxylipins is unknown. This study aimed to investigate alterations in the oxylipin profiles of STEMI patients during ischemia and at various reperfusion time points following PPCI. Blood samples were collected from patients presenting with STEMI prior to PPCI (Isch, n = 45) and subsequently 2 h following successful reperfusion by PPCI (R-2 h, n = 42), after 24 h (R-24 h, n = 44), after 48 h (R-48 h, n = 43), and then 30 days post PPCI (R-30 d, n = 29). As controls, blood samples were collected from age- and sex-matched patients with non-obstructive coronary artery disease after diagnostic coronary angiography. High-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) using deuterated standards was used to identify and quantify oxylipins. In patients presenting with STEMI prior to reperfusion (Isch group), the levels of docosahexaenoic acid (DHA)-derived oxylipins were significantly higher when compared with controls. Their levels were also significantly correlated with the peak levels of creatine kinase (CK) and troponin T(TnT) before reperfusion (CK: r = 0.33, p = 0.046, TnT: r = 0.50, p = 1.00 × 10-3). The total concentrations of oxylipins directly produced by 5-lipoxygenase (5-LOX) were also significantly elevated in the Isch group compared with controls. The ratio of epoxides (generated through epoxygenase) to diols (generated by soluble epoxide hydrolysis (sEH)) was significantly lower in the Isch group compared with the controls. Following reperfusion, there was an overall reduction in plasma oxylipins in STEMI patients starting at 24 h post PPCI until 30 days. Univariate receiver operating characteristic (ROC) curve analysis also showed that an elevated ratio of epoxides to diols during ischemia is a predictor of smaller infarct size in patients with STEMI. This study revealed a large alteration in plasma oxylipins in patients presenting with STEMI when compared with controls. Total oxylipin levels rapidly reduced post reperfusion with stable levels reached 24 h post reperfusion and maintained for up to 30 days post infarct. Given the shifts in plasma oxylipins following coronary artery reperfusion, further research is needed to delineate their clinical impact in STEMI patients.

The Plasma Oxylipidome Links Smoking Status to Peripheral Artery Disease.

Peripheral artery disease (PAD) is prevalent among individuals with a history of tobacco smoking. Although oxidation of lipids may contribute to atherogenesis in vascular disease, enzymatically and nonenzymatically produced oxidized lipids can have varying and contrasting physiological effects. The underlying mechanisms of atherogenic vulnerability can be better elucidated with the recent advances in oxylipidome quantification using HPLC-MS/MS technology. In a randomized, controlled clinical trial, the plasma oxylipidome was analyzed in participants living with PAD by smoking status (n = 98) and in nonsmoking comparators without chronic disease (n = 20). Individuals with PAD had approximately a four-fold higher level of total plasma oxylipins versus the comparator. Cessation of smoking in individuals with PAD was associated with significantly lower levels of linoleic acid-derived TriHOMEs, greater levels of omega-3 fatty acid-derived oxylipins, and greater levels of nonfragmented oxidized phosphatidylcholines (OxPCs). Individuals living with PAD but without a history of smoking, exhibited higher levels of the putative atherogenic fragmented OxPCs versus individuals who currently or previously smoked. These data implicate the plasma oxylipidome in PAD and that smoking cessation is associated with a less inflammatory profile. Furthermore, fragmented OxPCs may play a more significant role in the pathophysiology of PAD in individuals without a history of smoking.

Comparing Flaxseed and Perindopril in the Prevention of Doxorubicin and Trastuzumab-Induced Cardiotoxicity in C57Bl/6 Mice.

BACKGROUND: Two anti-cancer agents, doxorubicin (DOX) and trastuzumab (TRZ), are commonly used in the management of breast cancer in women. Despite their efficacy in reducing the morbidity and mortality of individuals with breast cancer, the use of these agents is limited by adverse cardiotoxic side effects. Both the nutraceutical agent flaxseed (FLX) and the pharmaceutical drug perindopril (PER) have been studied individually in the prevention of chemotherapy-mediated cardiac dysfunction. The objective of this study was to determine whether the prophylactic administration of FLX is comparable and/or synergistic with PER in preventing DOX + TRZ-induced cardiotoxicity. METHODS: Over a six-week period, 81 wild-type C57Bl/6 female mice (8-12 weeks old) were randomized to receive regular chow (RC) or 10% FLX-supplemented diets with or without PER (3 mg/kg/week; oral gavage). Starting at week 4, mice were randomized to receive a weekly injection of saline or DOX (8 mg/kg) + TRZ (3 mg/kg). Serial echocardiography was conducted weekly and histological and biochemical analyses were performed at the end of the study. RESULTS: In mice treated with RC + DOX + TRZ, left ventricular ejection (LVEF) decreased from 75 ± 2% at baseline to 37 ± 3% at week 6. However, prophylactic treatment with either FLX, PER, or FLX + PER partially preserved left ventricular systolic function with LVEF values of 61 ± 2%, 62 ± 2%, and 64 ± 2%, respectively. The administration of FLX, PER, or FLX + PER was also partially cardioprotective in preserving cardiomyocyte integrity and attenuating the expression of the inflammatory biomarker NF-κB due to DOX + TRZ administration. CONCLUSION: FLX was equivalent to PER at preventing DOX + TRZ-induced cardiotoxicity in a chronic in vivo murine model.

PD146176 affects human EA.hy926 endothelial cell function by differentially modulating oxylipin production of LOX, COX and CYP epoxygenase.

Oxylipins are oxygenated derivatives of polyunsaturated fatty acids, generated by COX, LOX and CYP enzymes, that regulate various aspects of endothelial cell physiology. Although 15-LOX and its products are positively associated with atherosclerosis, the relevant mechanisms have not been explored. The current study examined the effects of PD146176 (PD), a putative 15-LOX inhibitor, on EA.hy926 endothelial cell functions in the growing and confluent states. The effects of PD on endothelial cell oxylipin production (profiled by LC/MS/MS), cell viability, proliferation, eNOS activity, ICAM-1 and VE-cadherin levels were assessed. The contribution of signaling pathways relevant to endothelial function (p38 MAPK, Akt, PPARα) were also investigated. PD treatment for 30 min did not block formation of individual 15-LOX oxylipins, but 20 µM PD stimulated the accumulation of total LOX and COX products, while reducing several individual CYP products generated by epoxygenase. At 20 µM, the accumulated total oxylipins were primarily LOX-derived (86%) followed by COX (12%) and CYP (2%). PD altered cell functions by upregulating p38 MAPK and PPARα and downregulating Akt in a dose-dependent fashion. These observations suggest a link between PD-induced changes in oxylipins and altered endothelial cell functions via specific signaling pathways. In conclusion, the results of this study imply that PD does not function as a 15-LOX inhibitor in EA.hy926 endothelial cells, and instead inhibits CYP epoxygenase. These findings suggest that the cellular function changes induced by PD may be contingent upon its ability to modulate total oxylipin production, particularly by the LOX and CYP families.

Changes in snail chemical profiles through host-parasite interactions.

Host behavior may be modified by their parasites to increase the likelihood of transmission, but mechanisms underlying these interactions are not well understood. Hosts and parasites release chemical signaling molecules, like oxylipins, that may affect transmission. Oxylipins are oxygenated metabolites of fatty acids that function as signaling molecules and have essential physiological and functional roles. Yet, the limited taxonomic and contextual scope of these studies constrains our ability to understand their role in parasite-modified behavior. We characterized oxylipins in field-collected File Ramshorn snails, Planorbella pilsbryi. We tested for differences in oxylipin profiles based on infection status (infected with the trematode Echinostoma trivolvis lineage a and uninfected) and parasite activity (high and low). Snail-conditioned water samples were produced by placing five snails into artificial spring water for four hours. Oxylipins were extracted from snail-conditioned water samples and quantified using high performance liquid chromatography-tandem mass spectrometry. Infected snails emitted 69 oxylipins in higher amounts, with 37 only released by this group. Within infected snails, 18 oxylipins were emitted in higher amounts in snails with increased parasite activity. Oxylipins emitted in higher amounts by infected snails with increased parasite activity were predominantly derived from the cytochrome P450 pathway. As infected snails emit different oxylipin profiles than uninfected snails, their production may play a role in altering transmission success. By characterizing the oxylipins produced by snails, and how they are altered by infection, we can test their physiological and ecological roles in freshwater systems.

Density-Dependent Prophylaxis in Freshwater Snails Driven by Oxylipin Chemical Cues.

While animal aggregations can benefit the fitness of group members, the behaviour may also lead to higher risks of parasite infection as group density increases. Some animals are known to moderate their investment in immunity relative to the risk of infection. These animals exhibit density-dependent prophylaxis (DDP) by increasing their immune investment as group density increases. Despite being documented in many taxa, the mechanisms of DDP remain largely unexplored. Snails are known to aggregate and experience large fluctuations in density and serve as required hosts for many parasites. Further, they are known to use chemical cues to aggregate. To test whether freshwater snails exhibit DDP and investigate the role that chemical signaling compounds may play in triggering this phenomenon, we performed four experiments on the freshwater snail Stagnicola elodes, which is a common host for many trematode parasite species. First, we tested if DDP occurred in snails in laboratory-controlled conditions (control vs snail-conditioned water) and whether differences in exposure to chemical cues affected immune function. Second, we used gas chromatography to characterize fatty acids expressed in snail-conditioned water to determine if precursors for particular signaling molecules, such as oxylipins, were being produced by snails. Third, we characterized the oxylipins released by infected and uninfected field-collected snails, to better understand how differences in oxylipin cocktails may play a role in inducing DDP. Finally, we tested the immune response of snails exposed to four oxylipins to test the ability of specific oxylipins to affect DDP. We found that snails exposed to water with higher densities of snails and raised in snail-conditioned water had higher counts of haemocytes. Additionally, lipid analysis demonstrated that fatty acid molecules that are also precursors for oxylipins were present in snail-conditioned water. Trematode-infected snails emitted 50 oxylipins in higher amounts, with 24 of these oxylipins only detected in this group. Finally, oxylipins that were higher in infected snails induced naïve snails to increase their immune responses compared to sham-exposed snails. Our results provide evidence that snails exhibit DDP, and the changes in oxylipins emitted by infected hosts may be one of the molecular mechanisms driving this phenomenon.

Saskatoon berry supplementation prevents cardiac remodeling without improving renal disease in an animal model of reno-cardiac syndrome.

Saskatoon berry (SKB) may have the potential to counter reno-cardiac syndrome owing to its antioxidant capacity. Here, we investigated the renal and cardiovascular effects of SKB-enriched diet in a rat model of reno-cardiac disease. Two groups of wild-type rats (+/+) and two groups of Hannover Sprague-Dawley (Han:SPRD-Cy/+) rats were given either regular diet or SKB diet (10% w/w total diet) for 8 weeks. Body weight, kidney weight, kidney water content, and left ventricle (LV) weight were measured. Blood pressure (BP) was measured by the tail-cuff method. Echocardiography was performed to assess cardiac structure and function. Serum creatinine and malondialdehyde (MDA) were also measured. Han:SPRD-Cy/+ rats had significantly higher kidney weight, kidney water content, LV weight, BP, and creatinine compared with wild-type rats (+/+). The SKB diet supplementation did not reduce kidney weight, kidney water content, BP, and LV weight in Han:SPRD-Cy/+ rats. The SKB diet also resulted in higher systolic BP in Han:SPRD-Cy/+rats. Han:SPRD-Cy/+rats showed cardiac structural remodeling (higher LV wall thickness) without any cardiac functional abnormalities. Han:SPRD-Cy/+ rats also had significantly higher creatinine whereas the concentration of MDA was not different. The SKB diet supplementation reduced cardiac remodeling and the concentration of MDA without altering the concentration of creatinine in Han:SPRD-Cy/+ rats. In conclusion, Han:SPRD-Cy/+ rats developed significant renal disease, high BP, and cardiac remodeling by 8 weeks without cardiac functional impairment. The SKB diet may be useful in preventing cardiac remodeling and oxidative stress in Han:SPRD-Cy/+rats. PRACTICAL APPLICATIONS: Saskatoon berry (SKB) is widely consumed as fresh fruit or processed fruit items and has significant commercial value. It may offer health benefits due to the presence of bioactives such as anthocyanins. SKB has very good culinary flavors, and it is an economically viable fruit crop in many parts of the world. The disease-modifying benefits of SKB are mainly ascribed to the antioxidant nature of its bioactive content. Polycystic kidney disease is a serious condition that can lead to renal and cardiac abnormalities. Here, we showed that SKB supplementation was able to mitigate cardiac remodeling and lower the level of a marker of oxidative stress in an animal model of reno-cardiac syndrome. Our study suggests that SKB possesses beneficial cardioprotective properties. Further evidence from human studies may help in increasing the consumption of SKB as a functional food.

Oils Rich in α-Linolenic Acid or Docosahexaenoic Acid Have Distinct Effects on Plasma Oxylipin and Adiponectin Concentrations and on Monocyte Bioenergetics in Women with Obesity.

BACKGROUND: Omega-3 fatty acids, including DHA and α-linolenic acid (ALA), are proposed to improve metabolic health by reducing obesity-associated inflammation. Their effects are mediated in part by conversion to oxylipins. ALA is relatively understudied, and direct comparisons to other omega-3 fatty acids are limited. OBJECTIVES: We compared the effects of equal doses of ALA and DHA on plasma oxylipins and markers of metabolic health in women with obesity. METHODS: We carried out a randomized, double-blind, crossover clinical trial where women aged 20-51 with a BMI of 30-51 kg/m2 were supplemented with 4 g/day of ALA or DHA for 4 weeks in the form of ALA-rich flaxseed oil or DHA-rich fish oil. The primary outcome, the plasma oxylipin profile, was assessed at Days 0 and 28 of each phase by HPLC-MS/MS. Plasma fatty acids, inflammatory markers, and the monocyte glucose metabolism were key secondary outcomes. Data were analyzed using a mixed model. RESULTS: Compared to the baseline visit, there were higher plasma levels of nearly all oxylipins derived from DHA (3.8-fold overall; P < 0.001) and EPA (2.7-fold overall; P < 0.05) after 28 days of fish-oil supplementation, while there were no changes to oxylipins after flaxseed-oil supplementation. Neither supplement altered plasma cytokines; however, adiponectin was increased (1.1-fold; P < 0.05) at the end of the fish-oil phase. Compared to the baseline visit, 28 days of flaxseed-oil supplementation reduced ATP-linked oxygen consumption (0.75-fold; P < 0.05) and increased spare respiratory capacity (1.4-fold; P < 0.05) in monocytes, and countered the shift in oxygen consumption induced by LPS. CONCLUSIONS: Flaxseed oil and fish oil each had unique effects on metabolic parameters in women with obesity. The supplementation regimens were insufficient to reduce inflammatory markers but adequate to elicit increases in omega-3 oxylipins and adiponectin in response to fish oil and to alter monocyte bioenergetics in response to flaxseed oil. This trial was registered at clinicaltrials.gov as NCT03583281.

Oxylipin profiles and levels vary by skeletal muscle type, dietary fat and sex in young rats.

Polyunsaturated fatty acids (PUFA)-derived bioactive lipid mediators called oxylipins have been shown to influence muscle growth, inflammation and repair in select muscles. Since individual oxylipins have varying effects and potencies, broad profiling in differing muscle types is required to further understand their overall effects. In addition, diet and sex are key determinants of oxylipin levels. Therefore, to provide comprehensive data on oxylipin profiles in rat soleus (SO), red gastrocnemius (RG), and white gastrocnemius (WG) muscles, female and male weanling Sprague-Dawley rats were provided control or experimental diets enriched in n-3 (ω-3) or n-6 (ω-6) PUFA for 6 weeks. Free oxylipin analysis by HPLC/MS/MS revealed that SO muscle had 25% more oxylipins and 4-13 times greater oxylipin mass than WG muscle. Dietary n-3 PUFA (α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) each increased n-3 oxylipins derived directly from their precursors and several that were not direct precursors, while reducing arachidonic acid derived oxylipins. Dietary linoleic acid had few effects on oxylipins. Oxylipins with a sex effect were higher in females in SO and RG. Oxylipins generally reflected the effects of diet and sex on PUFA, but there were exceptions. These fundamental oxylipin profile data provide groundwork knowledge and context for future research on muscle oxylipin functions. Novelty: Rat SO compared with RG and WG muscles have a higher number and greater mass of oxylipins. Oxylipins generally reflect diet effects on PUFA in all muscles, but there are notable exceptions. Oxylipins in SO and RG are higher in females.

Rationale and design of a randomized controlled trial examining the effects of marine- and plant-sourced omega-3 fatty acid supplements on octadecanoid profiles and inflammation in females with obesity (OXBIO trial).

INTRODUCTION: Consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) has been reported to provide health benefits, but it remains unknown whether the fatty acids themselves or their oxygenated metabolites, oxylipins, are responsible for the beneficial effects. PURPOSE: This paper describes the design and rationale of a randomized, double-blinded, cross-over study comparing the effects of α-linolenic acid (ALA)-rich flax oil and docosahexaenoic acid (DHA)-rich fish oil supplementation on circulating oxylipin profiles in females with obesity, in relation to obesity-induced inflammation. METHODS AND ANALYSIS: Pre-menopausal females (n = 24) aged 20-55 with a BMI ≥30, will consume capsules containing flaxseed oil (4 g ALA/day) or fish oil (4 g DHA + 0.8 g EPA/day) during 4-week supplementation phases, with a minimum 4-week washout. The primary outcome is alterations in plasma oxylipin profiles. Secondary outcomes include effects of supplementation on circulating markers of inflammation, adipokines, plasma fatty acid composition, blood lipid profile, anthropometrics, oxylipin and cytokine profiles of stimulated immune cells, monocyte glucose metabolism, blood pressure and pulse wave velocity. ETHICS AND SIGNIFICANCE: This trial has been approved by the University of Manitoba Biomedical Research Ethics Board and the St. Boniface Hospital Research Review Committee. The study will provide information regarding the effects of ALA and DHA supplementation on oxylipin profiles in obese but otherwise healthy females. Additionally, it will improve our understanding of the response of circulating inflammatory mediators originating from immune cells, adipose tissue and the liver to n-3 PUFA supplementation in relation to the metabolic features of obesity.

Regulation of docosahexaenoic acid-induced apoptosis of confluent endothelial cells: Contributions of MAPKs and caspases.

Endothelial cells, which help to maintain vascular homeostasis, can be functionally modulated by polyunsaturated fatty acids. Previously, we reported that docosahexaenoic acid (DHA) reduced the viability of confluent EA.hy926 endothelial cells with caspase-3 activation. This study therefore examined the molecular mechanism by which DHA affects the viability of confluent cells, with a focus on the interaction between caspase-9, caspase-8, caspase-3, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) by Western blotting. Our results revealed that DHA induces apoptosis of confluent cells through both intrinsic and extrinsic pathways, which requires activation of p38 MAPK, and involves activation of JNK, caspase-9, caspase-8 and caspase-3 with the exception that cleavage of caspase-8 was incomplete and truncated BID was not detected at the maximum time (8 h) examined. Apoptosis induced by high levels of DHA in healthy endothelial cells is achieved through positive feedback loops linking these MAPKs to multiple caspases, as well as negative feedback from p38 MAPK to JNK. However, only p38 MAPK is crucial in apoptosis induction in comparison with JNK or any other caspase examined. This study has expanded the knowledge on the molecular mechanism of DHA-induced apoptosis in human endothelial cells and has also implied the differential roles of MAP kinases and caspases in apoptosis.

Time Course and Sex Effects of α-Linolenic Acid-Rich and DHA-Rich Supplements on Human Plasma Oxylipins: A Randomized Double-Blind Crossover Trial.

BACKGROUND: Differences in health effects of dietary α-linolenic acid (ALA) and DHA are mediated at least in part by differences in their effects on oxylipins. OBJECTIVES: Time course and sex differences of plasma oxylipins in response to ALA- compared with DHA-rich supplements were examined. METHODS: Healthy men and women, aged 19-34 y and BMI 18-28 kg/m2, were provided with capsules containing ∼4 g/d of ALA or DHA in a randomized double-blind crossover study with >6-wk wash-in and wash-out phases. Plasma PUFA and oxylipin (primary outcome) concentrations at days 0, 1, 3, 7, 14, and 28 of supplementation were analyzed by GC and HPLC-MS/MS, respectively. Sex differences, supplementation and time effects, and days to plateau were analyzed. RESULTS: ALA supplementation doubled ALA concentrations, but had no effects on ALA oxylipins after 28 d, whereas DHA supplementation tripled both DHA and its oxylipins. Increases in DHA oxylipins were detected as early as day 1, and a plateau was reached by days 5-7 for 11 of 12 individual DHA oxylipins and for total DHA oxylipins. Nine individual DHA oxylipins reached a plateau in females with DHA supplementation, compared with only 4 in males. A similar time course and sex difference pattern occurred with EPA and its oxylipins with DHA supplementation. DHA compared with ALA supplementation also resulted in higher concentrations of 4 individual arachidonic acids, 1 linoleic acid, and 1 dihomo-γ-linolenic acid oxylipin, despite not increasing the concentrations of these fatty acids, further demonstrating that oxylipins do not always reflect their precursor PUFA. CONCLUSIONS: DHA compared with a similar dose of ALA has greater effects on both n-3 and n-6 oxylipins in young, healthy adults, with differences in response to DHA supplementation occurring earlier and being greater in females. These findings can help explain differences in dietary effects of ALA and DHA.This study was registered at clinicaltrials.gov as NCT02317588.