Search

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., (Copyright © 2022. Published by Elsevier B.V.)

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., (Copyright © 2022 Elsevier B.V. All rights reserved.)

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.

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Friesen, Li, Sykes, Stout, Aukema, Kumar and Detwiler.)

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.

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., (© 2021 Her Majesty the Queen in Right of Canada Journal of Food Biochemistry © 2021 Wiley Periodicals LLC. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.)

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., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

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., (Copyright © 2021. Published by Elsevier Ltd.)

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., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: Cardiovascular disease, a major cause of mortality and morbidity, exhibits sexual dimorphism since the onset of cardiovascular disease occurs later in women than in men. The loss of cardioprotection in older women may be due to an increase in arterial stiffness after menopause. Free fatty acid metabolites of polyunsaturated fatty acids, called oxylipins, are known to impact vessel function and may be responsible for the vascular benefits of polyunsaturated fatty acids. The objectives of this study were to compare the plasma oxylipin profiles of young females (20-55 years), older females (55 + ), and older males (55 + ) and to identify associations between oxylipins and cardiovascular disease risk factors, such as obesity and arterial stiffness. Approach and Results: We quantified plasma oxylipins by high-performance liquid chromatography-tandem mass spectrometry in archived samples taken from completed clinical trials. We identified 3 major 12-lipoxygenase products, 12-hydroxy-eicosatetraenoic acid, 12-hydroxy-eicosapentaenoic acid, and 14-hydroxy-docosahexaenoic acid, that are present at high levels in young females compared with older females and males. These oxylipins also decreased with obesity and displayed robust negative associations with arterial stiffness as assessed by brachial-ankle pulse wave velocity. According to multiple linear regression modeling, these associations were maintained even after correcting for body mass index category combined with either age, menopausal status, or estradiol levels. Using linear discriminant analysis, the combination of these 3 oxylipins effectively distinguished participants according to both brachial-ankle pulse wave velocity risk group and age., Conclusions: Higher 12-lipoxygenase oxylipin plasma concentrations associated with lower arterial stiffness in premenopausal females may be an important contributing factor to sex differences in cardiovascular disease. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT01661543, NCT01562171, NCT01890330, NCT02571114 and NCT02317588.

Polycystic kidney disease (PKD) is characterized by the proliferation of fluid-filled kidney cysts that enlarge over time, causing damage to the surrounding kidney and ultimately resulting in kidney failure. Both increased cell proliferation and fluid secretion are stimulated by increased cyclic adenosine monophosphate (cAMP) in PKD kidneys, so many treatments for the disease target cAMP lowering. Prostaglandins (PG) levels are elevated in multiple animal models of PKD and mediate many of their effects by elevating cAMP levels. Inhibiting the production of PG with cyclooxygenase 2 (COX2) inhibitors reduces PG levels and reduces disease progression. However, COX inhibitors also block beneficial PG and can cause nephrotoxicity. In an orthologous model of the main form of PKD, PGD 2 and PGI 2 were the two PG highest in kidneys and most affected by a COX2 inhibitor. Future studies are needed to determine whether specific blockage of PGD 2 and/or PGI 2 activity would lead to more targeted and effective treatments with fewer undesirable side-effects., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Oxylipins, which are circulating bioactive lipids generated from polyunsaturated fatty acids (PUFAs) by cyclooxygenase, lipooxygenase and cytochrome P450 enzymes, have diverse effects on endothelial cells. Although studies of the effects of oxylipins on endothelial cell function are accumulating, a review that provides a comprehensive compilation of current knowledge and recent advances in the context of vascular homeostasis is lacking. This is the first compilation of the various in vitro, ex vivo and in vivo reports to examine the effects and potential mechanisms of action of oxylipins on endothelial cells. The aggregate data indicate docosahexaenoic acid-derived oxylipins consistently show beneficial effects related to key endothelial cell functions, whereas oxylipins derived from other PUFAs exhibit both positive and negative effects. Furthermore, information is lacking for certain oxylipin classes, such as those derived from α-linolenic acid, which suggests additional studies are required to achieve a full understanding of how oxylipins affect endothelial cells., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Ex vivo studies suggest that increased renal prostanoids can mediate effects of high-protein (HP) compared with low-protein (LP) diets on normal and diseased kidneys. However, a short-term HP feeding study in normal male rats failed to demonstrate higher renal prostanoids in vivo., Objectives: The aim of the present study was to investigate whether long-term HP feeding alters renal prostanoids in male and female mice, with and without kidney disease., Methods: Weanling normal mice (CD1) and mice with kidney disease (CD1-pcy/pcy mice) were fed standard diets with normal protein [NP, 20% of energy (%E)] or HP (35%E) for 13 wk. Renal disease was assessed by histomorphometric analysis of cysts and fibrosis, and measurement of serum urea nitrogen (SUN) and creatinine concentrations. Targeted analysis of renal oxylipins was performed by HPLC-MS/MS., Results: The HP diet increased kidney size and water content of normal kidneys, and worsened disease in CD1-pcy/pcy mice as indicated by higher (P < 0.05) kidney weights (8-31%), water content (8-10%), cyst volume (36-60%), fibrous volume (44-53%), and SUN (47-55%). Diseased compared with normal kidneys had higher (P < 0.05) concentrations of 6 of 11 prostanoids and lower (P < 0.05) concentrations of 33 of 54 other oxylipins. This is consistent with previously known effects of dietary HP and disease effects on the kidney. However, the HP diet did not alter renal prostanoids and other renal oxylipins in either normal or diseased kidneys (P < 0.05), despite having the expected physiological effects on normal and diseased kidneys. This study also showed that females have higher concentrations of renal prostanoids [9 of 11 prostanoids higher (P < 0.05) in females], but lower concentrations of other oxylipins [28 of 54 other oxylipins lower (P < 0.05) in females]., Conclusions: The effects of HP diets on normal and diseased kidneys in CD1 and CD1-pcy/pcy mice are independent of renal oxylipin alterations., (Copyright © The Author(s) 2020.)

The use of dietary supplements as an alternative treatment for joint-related pathologies such as osteoarthritis (OA) is increasing. However, there is little scientific evidence to support the intended use. The aim of this study was to evaluate the anti-inflammatory effects of creatine- and amino acid-based supplements in primary cultured canine chondrocytes (CnCs) as an in-vitro model of OA and compare the effects to more commonly used agents, such as the non-steroidal anti-inflammatory drug (NSAID), carprofen, and the joint supplement, glucosamine (GS). CnCs were stimulated with interleukin-1β (IL-1β) and the subsequent release of prostaglandin E2 (PGE2) and tumor necrosis factor alpha (TNFα) was measured using an enzyme-linked immunosorbent assay (ELISA). Changes in oxylipins were also assessed using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). All compounds examined were able to significantly reduce the release of PGE2 and TNFα and were associated with reductions in cyclooxygenase-2 (COX-2) expression and nuclear factor-kappaB (NF-κB) phosphorylation. The creatine- and amino acids-based supplements also altered the profile of oxylipins produced. All compounds examined were less effective at reducing the release of PGE2 than carprofen. Carprofen significantly increased release of TNFα from CnCs, however, while the other agents reduced TNFα release. This study suggests that creatine- and amino acid-based supplements may have a beneficial role in preventing inflammation within the joint and that further studies are warranted.

Background: Increased levels of cyclooxygenase (COX) derived oxylipins is the earliest and most consistent alteration in the renal oxylipin profile in diverse models of cystic kidney diseases. Therefore, we examined whether a COX2 inhibitor would reduce disease progression in the Pkd2 WS25/- mouse model of autosomal dominant polycystic kidney disease (ADPKD)., Methods: Weanling normal and diseased male Pkd2 mice were provided diets that provided 0 or 50 mg celecoxib/kg body weight/day, for 13 weeks. Renal disease and function were assessed by histomorphometric analysis of renal cysts and measurement of serum creatinine and urea nitrogen (SUN) levels. Targeted lipidomic analysis of renal oxylipins was performed by HPLC-MS/MS., Results: Diseased mice had significant cyst involvement and reduced renal function as indicated by elevated serum creatinine and SUN. Celecoxib reduced cyst area by 48%, cyst volume by 70%, and serum creatinine and SUN by 20% and 16%, respectively. Consistent with our previous studies, 8 of the 11 COX derived oxylipins were higher in diseased kidneys. In addition, 24 of 33 lipoxygenase (LOX) derived oxylipins and 7 of 16 cytochrome P450 (CYP) derived oxylipins were lower in diseased kidneys. Celecoxib reduced total and five of the eight individual elevated COX oxylipins and increased 5 of 24 LOX and 5 of 7 CYP oxylipins that were reduced by disease., Conclusions: COX2 inhibition ameliorates disease progression, improves renal function and improves the altered oxylipins in Pkd2 mice. This represents a potential new approach for treatment of ADPKD, a disorder for which no effective treatment currently exists.

Oxylipins and fatty acids may be novel therapeutic targets for cardiovascular disease. The objective was to determine if plasma oxylipins or fatty acids can influence the odds of cardiovascular/cerebrovascular events. In 98 patients (25 female, 73 male) with peripheral artery disease, the prevalence of transient ischemic attacks, cerebrovascular accidents, stable angina, and acute coronary syndrome was n = 16, 10, 16, and 24, respectively. Risk factors such as being male, diagnosed hypertension, diabetes mellitus, and hyperlipidemia were not associated with events. Plasma fatty acids and oxylipins were analyzed with gas chromatography and HPLC-MS/MS, respectively. None of 24 fatty acids quantified were associated with events. In contrast, 39 plasma oxylipins were quantified, and 8 were significantly associated with events. These 8 oxylipins are known regulators of vascular tone. For example, every 1 unit increase in Thromboxane B 2 /Prostaglandin F 1 α and every 1 nmol/L increase in plasma 16-hydroxyeicosatetraenoic acid, thromboxane B2, or 11,12-dihydroxyeicosatrienoic acid (DiHETrE) increased the odds of having had ≥2 events versus no event (p < 0.05). The greatest predictor was plasma 8,9-DiHETrE, which increased the odds of acute coronary syndrome by 92-fold. In conclusion, specific oxylipins were highly associated with clinical events and may represent specific biomarkers and (or) therapeutic targets of cardiovascular disease.

Alzheimer disease (AD) is becoming one of the most prevalent neurodegenerative conditions worldwide. Although the disease progression is becoming better understood, current medical interventions can only ameliorate some of the symptoms but cannot slow disease progression. Neuroinflammation plays an important role in the advancement of this disorder, and n-3 (ω-3) polyunsaturated fatty acids (PUFAs) are involved in both the reduction in and resolution of inflammation. These effects may be mediated by the anti-inflammatory and proresolving effects of bioactive lipid mediators (oxylipins) derived from n-3 PUFAs [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in fish oil. Although interventions have generally used fish oil containing both EPA and DHA, several studies that used either EPA or DHA alone or specific oxylipins derived from these fatty acids indicate that they have distinct effects. Both DHA and EPA can reduce neuroinflammation and cognitive decline, but EPA positively influences mood disorders, whereas DHA maintains normal brain structure. Fewer studies with a plant-derived n-3 PUFA, α-linolenic acid, suggest that other n-3 PUFAs and their oxylipins also may positively affect AD. Further research identifying the unique anti-inflammatory and proresolving properties of oxylipins from individual n-3 PUFAs will enable the discovery of novel disease-management strategies in AD., Competing Interests: 2 Author disclosures: JG Devassy, S Leng, M Gabbs, M Monirujjaman, and HM Aukema, no conflicts of interest., (© 2016 American Society for Nutrition.)

The human blood-brain barrier (BBB) is the restrictive barrier between the brain parenchyma and the circulating blood and is formed in part by microvessel endothelial cells. The brain contains significant amounts of arachidonic acid (ARA), and docosahexaenoic acid (DHA), which potentially give rise to the generation of bioactive oxylipins. Oxylipins are oxygenated fatty acid metabolites that are involved in an assortment of biological functions regulating neurological health and disease. Since it is not known which oxylipins are generated by human brain microvessel endothelial cells (HBMECs), they were incubated for up to 30 min in the absence or presence of 0.1-mM ARA, eicosapentaenoic acid (EPA) or DHA bound to albumin (1:1 molar ratio), and the oxylipins generated were examined using high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). Of 135 oxylipins screened in the media, 63 were present at >0.1 ng/mL at baseline, and 95 were present after incubation with fatty acid. Oxylipins were rapidly generated and reached maximum levels by 2-5 min. While ARA, EPA and DHA each stimulated the production of oxylipins derived from these fatty acids themselves, ARA also stimulated the production of oxylipins from endogenous 18- and 20-carbon fatty acids, including α-linolenic acid. Oxylipins generated by the lipoxygenase pathway predominated both in resting and stimulated states. Oxylipins formed via the cytochrome P450 pathway were formed primarily from DHA and EPA, but not ARA. These data indicate that HBMECs are capable of generating a plethora of bioactive lipids that have the potential to modulate BBB endothelial cell function.

Purpose: The primary endpoint was to determine the plasma concentration of alpha-linolenic acid (ALA), and its metabolites, following milled flaxseed consumption at four doses. Secondary outcomes focused on plasma enterolignan concentrations and the effects on tolerability, platelet aggregation, plasma lipids and urinary thromboxane levels., Methods: Healthy, younger adults (n = 34; 18-49 years old) were randomized into four groups consuming one muffin daily for 30 days fortified with 10, 20, 30 or 40 g of milled flaxseed. Blood and urine were collected at baseline and 4 weeks., Results: Plasma ALA concentrations increased with all flaxseed doses (P < 0.01), except the 20 g/day dose (P = 0.10), yet there was no significant dose-dependent response (P = 0.81). Only with the 30 g/day diet were n-3 polyunsaturated fatty acids (P = 0.007), and eicosapentaenoic acid (EPA) (P = 0.047) increased from baseline values. Docosapentaenoic acid and docosahexaenoic acid were not detected at any dose. Plasma total enterolignan concentrations significantly increased over time in all treatment groups, yet despite a dose-dependent tendency, no between-group differences were detected (P = 0.22). Flaxseed was well tolerated, even at the highest dose, as there were no reported adverse events, changes in cholesterol, platelet aggregation or urinary 11-dehydro-thromboxane B2., Conclusions: In healthy, younger adults, 10 g/day of milled flaxseed consumption is sufficient to significantly increase circulating ALA and total enterolignan concentrations; however, 30 g/day is required to convert ALA to EPA. Although all doses were well tolerated, 40 g/day is too low to attenuate cholesterol in this population.

The blood-brain barrier, formed by microvessel endothelial cells, is the restrictive barrier between the brain parenchyma and the circulating blood. Arachidonic acid (ARA; 5,8,11,14-cis-eicosatetraenoic acid) is a conditionally essential polyunsaturated fatty acid [20:4(n-6)] and is a major constituent of brain lipids. The current study examined the transport processes for ARA in confluent monolayers of human brain microvascular endothelial cells (HBMEC). Addition of radioactive ARA to the apical compartment of HBMEC cultured on Transwell(®) inserts resulted in rapid incorporation of radioactivity into the basolateral medium. Knock down of fatty acid transport proteins did not alter ARA passage into the basolateral medium as a result of the rapid generation of prostaglandin E2 (PGE2 ), an eicosanoid known to facilitate opening of the blood-brain barrier. Permeability following ARA or PGE2 exposure was confirmed by an increased movement of fluorescein-labeled dextran from apical to basolateral medium. ARA-mediated permeability was attenuated by specific cyclooxygenase-2 inhibitors. EP3 and EP4 receptor antagonists attenuated the ARA-mediated permeability of HBMEC. The results indicate that ARA increases permeability of HBMEC monolayers likely via increased production of PGE2 which acts upon EP3 and EP4 receptors to mediate permeability. These observations may explain the rapid influx of ARA into the brain previously observed upon plasma infusion with ARA. The blood-brain barrier, formed by microvessel endothelial cells, is a restrictive barrier between the brain parenchyma and the circulating blood. Radiolabeled arachidonic acid (ARA) movement across, and monolayer permeability in the presence of ARA, was examined in confluent monolayers of primary human brain microvessel endothelial cells (HBMECs) cultured on Transwell(®) plates. Incubation of HBMECs with ARA resulted in a rapid increase in HBMEC monolayer permeability. The mechanism was mediated, in part, through increased prostaglandin E2 production from ARA which acted upon EP3 and EP4 receptors to increase HBMEC monolayer permeability., (© 2015 International Society for Neurochemistry.)

Oxylipins formed from polyunsaturated fatty acids (PUFAs) are the main mediators of PUFA effects in the body. They are formed via cyclooxygenase, lipoxygenase, and cytochrome P450 pathways, resulting in the formation of prostaglandins, thromboxanes, mono-, di-, and tri-hydroxy fatty acids (FAs), epoxy FAs, lipoxins, eoxins, hepoxilins, resolvins, protectins (also called neuroprotectins in the brain), and maresins. In addition to the well-known eicosanoids derived from arachidonic acid, recent developments in lipidomic methodologies have raised awareness of and interest in the large number of oxylipins formed from other PUFAs, including those from the essential FAs and the longer-chain n-3 (ω-3) PUFAs. Oxylipins have essential roles in normal physiology and function, but can also have detrimental effects. Compared with the oxylipins derived from n-3 PUFAs, oxylipins from n-6 PUFAs generally have greater activity and more inflammatory, vasoconstrictory, and proliferative effects, although there are notable exceptions. Because PUFA composition does not necessarily reflect oxylipin composition, comprehensive analysis of the oxylipin profile is necessary to understand the overall physiologic effects of PUFAs mediated through their oxylipins. These analyses should include oxylipins derived from linoleic and α-linolenic acids, because these largely unexplored bioactive oxylipins constitute more than one-half of oxylipins present in tissues. Because collated information on oxylipins formed from different PUFAs is currently unavailable, this review provides a detailed compilation of the main oxylipins formed from PUFAs and describes their functions. Much remains to be elucidated in this emerging field, including the discovery of more oxylipins, and the understanding of the differing biological potencies, kinetics, and isomer-specific activities of these novel PUFA metabolites., (© 2015 American Society for Nutrition.)

Background and Aims: Oxylipins, including eicosanoids, are highly bioactive molecules endogenously produced from polyunsaturated fatty acids. Oxylipins play a key role in chronic disease progression. It is possible, but unknown, if oxylipin concentrations change with the consumption of functional foods or differ with subject age., Methods: Therefore, in a parallel comparator trial, 20 healthy individuals were recruited into a younger (19-28years) or older (45-64years) age group (n=10/group). Participants ingested one muffin/day containing 30g of milled flaxseed (6g alpha-linolenic acid) for 4weeks. Plasma oxylipins were isolated through solid phase extraction, analyzed with HPLC-MS/MS targeted lipidomics, and quantified with the stable isotope dilution method., Results: At baseline, the older group exhibited 13 oxylipins ≥2-fold the concentration of the younger group. Specifically, pro-inflammatory oxylipins 5-hydroxyeicosatetraenoic acid, 9,10,13-trihydroxyoctadecenoic acid, and 9,12,13-trihydroxyoctadecenoic acid were significantly greater in the older (1.1±0.23nM, 5.6±0.84nM, and 4.5±0.58nM, respectively) versus the younger group (0.34±0.12nM, 3.5±0.33nM, and 3.0±0.24nM, respectively) (p<0.05). After 4weeks of flaxseed consumption the number of oxylipins that were ≥2-fold higher in the older versus the younger group was reduced to 3. 5-Hydroxyeicosatetraenoic acid, 9,10,13-trihydroxyoctadecenoic acid, and 9,12,13-trihydroxyoctadecenoic acid decreased in the older group to concentrations equivalent to the younger group after flaxseed consumption., Conclusion: These data suggest a potential role for oxylipins in the aging process and how nutritional interventions like flaxseed can beneficially disrupt these biological changes associated with inflammation and aging., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Scope: Dietary fish oil (FO) and soy protein (SP) are two interventions that slow disease progression in the Han:SPRD-Cy rat model of polycystic kidney disease (PKD). Inhibition of cyclooxygenase (COX)-derived eicosanoids also reduces disease progression, but the role of lipoxygenase (LOX) products in this disease is not known., Methods and Results: Since dietary FO and SP have been shown to alter eicosanoid formation via differing mechanisms, Han:SPRD-Cy rats were given diets containing either casein protein (CP) or SP, and soy oil (SO) or FO. Analysis of eicosanoids revealed that renal COX products were higher and LOX products were lower in diseased kidneys. SP feeding resulted in lower COX products, activity and COX1 protein and higher LOX products in the diseased kidneys in parallel with reduced renal cyst growth and fibrosis. By comparison, FO reduced both COX and LOX products produced from n-6 fatty acids and increased 3-series prostanoids in both normal and diseased cortex and medulla, but these differences did not parallel effects on disease., Conclusion: Renal COX-derived eicosanoids are elevated and LOX products are reduced in this model of kidney disease. The effects of dietary SP, but not FO, on renal eicosanoids parallel the effects on disease., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nephronophthisis (NPHP) is a pediatric form of hereditary polycystic kidney disease (PKD), and is the leading cause of end stage renal disease in children. The pcy mouse is an orthologous model of human NPHP, with a mutation in the Nphp3 gene. Renal phospholipase A2, cyclooxygenase (COX) 1 and cyclic AMP are elevated in this model, suggesting that eicosanoid formation may be altered. In another type of PKD observed in the Han:SPRD-Cy rat, inhibition of eicosanoid production slows disease progression. If renal eicosanoids are similarly altered in NPHP, potential for pharmacologic intervention also may exist for this disorder. Therefore, renal fatty acids and eicosanoids were determined in pcy and normal mice at 15, 30 and 60 days of age by gas chromatography and HPLC-tandem mass spectrometry, respectively. Renal cysts in enlarged kidneys were observed in pcy mice by 15 days of age and increased over time. Renal phospholipid ARA levels were higher in pcy compared to normal mice at 15 and 30 days. Eicosanoid differences were observed starting at 30 days, when the COX products 6-keto-prostaglandin (PG) F1α, thromboxane B2 and PGE2 were higher in pcy compared to normal kidneys. Overall, total COX products were elevated at 30 and 60 days. In contrast, the levels of the lipoxygenase (LOX) products were not altered until 60 days of age and these were lower in pcy kidneys compared to normal. These findings suggest that altered eicosanoids play a role in NPHP, and that manipulating these levels with pharmacologic agents may have therapeutic potential.

The current study examined the efficacy of graded doses of c9,t11 and t10,c12 CLA isomers on body composition, energy expenditure, hepatic and serum lipid liver biomarkers in hamsters. Animals (n = 105) were randomized to seven treatments (control, 1, 2, 3% of c9,t11; 1, 2, 3% of t10,c12) for 28 days. After 28 days treatment, 1-3% of t10,c12 lowered (p < 0.05) body fat mass compared to the control group. The 1-3% t10,c12 and 3% c9,t11 fed groups showed higher (p < 0.05) lean mass compared to other groups. We observed unfavorable changes in plasma total cholesterol and non-HDL cholesterol levels in animals fed with 3% t10,c12 CLA isomers. The 2%, 3% t10,c12 groups presented elevated (p < 0.05) ALT levels. The present data suggest that a diet enriched with more than 2% t10, c12 led to liver malfunction and poses unfavorable changes on plasma lipid profiles. The 1% t10,c12 CLA lowered (p < 0.05) body fat mass and increased (p < 0.05) lean body mass. The c9,t11 CLA has less potent actions than t10,c12 CLA. We conclude that the actions of CLA on energy and lipid metabolism are form and dose dependent in the hamster model.

Scope: Dietary soy protein reduces renal disease progression in a number of renal diseases, suggesting that plant compared with animal proteins may be renoprotective. The inclusion of other plant protein sources could enhance compliance of intervention diets, but the effects of other plant protein sources are not known., Methods and Results: Weanling Han:SPRD-cy rats with experimental polycystic kidney disease were given hemp-, pea- and soy protein-based diets compared with the standard AIN 93G diet with casein as the protein source. Kidneys from diseased rats given diets which contained soy or hemp protein compared with casein-based diets were less enlarged, had lower fluid content, smaller cyst volumes, less fibrosis, lower chemokine receptor 2 (CCR2) levels and normalized serum creatinine levels. Soy and hemp protein diets also normalized heart size, which was enlarged in diseased compared with normal rats consuming casein. Kidneys from diseased rats given pea protein compared with casein were more enlarged and had higher fluid content and cyst volumes, despite growing better and having lower serum creatinine and renal chemokine receptor 2 levels, and similar levels of renal fibrosis., Conclusion: Not all plant proteins are equally protective in experimental kidney disease and associated cardiac hypertrophy., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite evidence of potential antiobesity effects of high-protein (HP) diets, the impact of consuming diets with protein levels at the upper limit of the acceptable macronutrient distribution range (AMDR) on kidney health is unknown. To test whether HP diets affect renal health, whole plant and animal proteins in proportions that mimicked human diets were given to pigs, because their kidneys have a similar anatomy and function to those of humans. Adult female pigs received either normal-protein (NP) or HP (15 or 35% of energy from protein, respectively) isocaloric diets for either 4 or 8 mo. The higher protein in the HP diet was achieved by increasing egg and dairy proteins. Although there were initial differences in body weight and composition, after 8 mo these were similar in pigs consuming the NP and HP diets. The HP compared with NP diet, however, resulted in enlarged kidneys at both 4 and 8 mo. Renal and glomerular volumes were 60-70% higher by the end of the study. These enlarged kidneys had greater evidence of histological damage, with 55% more fibrosis and 30% more glomerulosclerosis. Renal monocyte chemoattractant protein-1 levels also were 22% higher in pigs given the HP diet. Plasma homocysteine levels were higher in the HP pigs at 4 mo and continued to be elevated by 35% at 8 mo of feeding. These findings suggest that long-term intakes of protein at the upper limit of the AMDR from whole protein sources may compromise renal health.

Long-term consumption of high-protein (HP) diets at 35% of energy is postulated to negatively influence bone health. Previous studies have not comprehensively examined the biochemical, physical, and biomechanical properties of bone required to arrive at this conclusion. Our objective in this study was to examine the long-term effect of a HP diet on bone metabolism, mass, and strength in rats. Adult female Sprague-Dawley rats (n = 80) were randomized to receive for 4, 8, 12, or 17 mo a normal-protein (NP) control diet (15% of energy) or a HP diet (35% of energy). Diets were balanced for calcium because the protein sources were rich in calcium. At each time point, measurements included weight, body composition, and bone mass using dual-energy X-ray absorptiometry, mechanical strength at the mid-diaphysis of femur and tibia, microarchitecture of femurs using microcomputerized tomography and serum osteocalcin, carboxy-terminal crosslinks of type I collagen (CTX), insulin-like growth factor-1 (IGF-1), leptin, and adiponectin. Effects of diet, time, and their interaction were tested using factorial ANOVA. The HP diet resulted in lower body weight, total body, and abdominal fat and higher lean mass. Serum leptin and adiponectin were greater in HP-fed than in NP-fed rats, but IGF-1 did not differ between the groups. Whereas the HP diet resulted in higher relative bone mineral content (g/kg) in the femur, tibia, and vertebrae, serum osteocalcin and CTX and bone internal architecture and biomechanical strength were unaffected. In conclusion, HP diets at 35% of energy lower body fat content without hindering the mechanical and weight-bearing properties of bone.

We recently demonstrated that (n-3) PUFA trigger the induction of apoptosis in the colon by enhancing phospholipid oxidation and mitochondrial Ca2+ accumulation. To further elucidate the mechanisms regulating oxidative stress-induced apoptosis in vivo, a 2 x 2 experiment was designed using both wild type (control) and manganese-dependent superoxide dismutase (SOD2) heterozygous knockout mice (SOD2(+/-)), which exhibit increased mitochondrial oxidative stress. Mice were fed diets differing only in the type of fat [corn oil or fish oil containing (n-3) PUFA] at 15% by weight for 4 wk. Dietary (n-3) PUFA treatment enhanced (22%) apoptosis in colonic crypts. In addition, SOD2 haploinsufficiency enhanced (20%) apoptosis, which was further increased (36%) by (n-3) PUFA feeding. Dietary lipid source and genotype interactively modulated nitrotyrosine levels (P = 0.027) and inflammation (P = 0.032). These findings demonstrate that the proapoptotic effects of (n-3) PUFA are enhanced in oxidatively stressed SOD2(+/-) mice. Thus, (n-3) PUFA appear to promote an oxidation-reduction imbalance in the intestine, which may directly or indirectly trigger apoptosis and thereby reduce colon cancer risk.

Conjugated linoleic acid (CLA) is anti-proliferative and anti-inflammatory in the Han:SPRD-cy rat model of kidney disease. We used different doses of CLA and examined effects on renal histological benefit, the renal PPARgamma system and hepatic and renal levels of CLA isomers. Male and female offspring of Han:SPRD-cy heterozygotes were fed diets with 0, 1 or 2% CLA isomer mixture for 12 weeks before dual-energy X-ray absorptiometry, harvest of renal and hepatic tissue for histologic and lipid analysis. Both CLA diets reduced body fat content in both genders but did not change lean body mass. CLA produced a dose dependent reduction in female renal cystic change. CLA reduced fibrosis, but this reduction was significantly less with higher dose in males. CLA reduced macrophage infiltration, tissue oxidized LDL content and proliferation of epithelial cells. Serum creatinine rose significantly in female animals fed CLA diets. CLA treatment did not change PPARgamma activation. A significant negative correlation with renal content of the 18:2 c9,t11 isomer and the sum of histologic effects was identified. CLA reduces histologic renal injury in the Han:SPRD-cy rat model probably inversely proportionate to c9,t11 renal content. Possible functional CLA toxicity at high dose in female animals warrants further exploration.

Dietary soya protein substitution for casein initiated at weaning slows disease progression in animal models of chronic renal disease. As there is increasing evidence that fetal programming can have a significant impact on kidney physiology and function in offspring, the objective of the current study was to determine whether exposure to soya protein in the diet earlier than weaning would have further benefits. Han:SPRD-cy (cy/+) breeder rats were fed a casein-based or soya protein-based diet 2 weeks prior to mating, throughout pregnancy and during lactation. Following this maternal period, 3-week-old pups were given either the same or the alternate diet for a 7-week weaning period. Dietary soya protein compared with casein in the maternal or weaning period both independently resulted in less renal inflammation (macrophage infiltration lower by 24% (P=0.0003) and 32% (P<0.001), respectively). When soya protein was given in both feeding periods, the effect was additive. Soya protein substitution for casein resulted in less oxidative damages as indicated by 28% lower oxidized-LDL staining (P=0.013) when present in the maternal period, or in the weaning period (by 56%, P<0.0001). Renal cell proliferation was reduced by 29-33% (P<0.05) in rats given soya protein whether the exposure was during the maternal or weaning period. Soya protein compared with casein in the maternal period also resulted in 33% (P=0.0013) less proteinuria, indicating superior renal function. Dietary soya protein during pregnancy and lactation represents a potential preventative approach in treating for those with congenital kidney diseases.

Flaxseed derivatives, including both oil and flax lignan, modify progression of renal injury in animal models, including Han:SPRD-cy polycystic kidney disease (PKD). Gender is a significant factor in the rates of progression of many forms of human renal disease, but the role of gender in the response to nutrition intervention in renal disease is unexplored. In this study, male and female Han:SPRD-cy rats or normal littermates were fed either corn oil (CO) or flax oil (FO) diets, with or without 20 mg/kg of the diet flax lignan secoisolaricinoresinol dyglycoside (SDG). Renal injury was assessed morphometrically and biochemically. Renal and hepatic PUFA composition was assessed by GC and renal PGE2 release by ELISA. FO preserved body weight in PKD males, with no effect in females. SDG reduced weight in both normal and PKD females. FO reduced proteinuria in both male and female PKD. FO reduced cystic change and renal inflammation in PKD males but reduced cystic change, fibrosis, renal inflammation, tissue lipid peroxides, and epithelial proliferation in PKD females. SDG reduced renal inflammation in all animals and lipid peroxides in PKD females. A strong interaction between SDG and FO was observed in renal FA composition of female kidneys only, suggesting increased conversion of C18 PUFA to C20 PUFA. FO reduced renal release of PGE2 in both genders. Gender influences the effects of flaxseed derivatives in Han:SPRD-cy rats. Gender-based responses to environmental factors, such as dietary lipid sources and micronutrients, may contribute to gender-based differences in disease progression rates.

Low-fat diets and diets containing n-3 fatty acids (FA) slow the progression of renal injury in the male Han:Sprague-Dawley (SPRD)-cy rat model of polycystic kidney disease. To determine whether these dietary fat effects are similar in females and in another model of renal cystic disease, in this study we used both male and female pcy mice to examine the effects of fat level and type on disease progression. Adult pcy mice were fed 4, 10, or 20 g soybean oil/100 g diet for 130 d in study 1. In study 2, weanling pcy mice were fed high or low levels of fat rich in 18:2n-6 (corn oil, CO), 18:3n-3 (flaxseed oil/CO 4:1 g/g, FO), or 22:6n-3 (algal oil/CO 4:1 g/g, DO) for 8 wk. In adult pcy mice, low- compared with high-fat diets lowered kidney weights (2.4 +/- 0.2 vs. 3.1 +/- 0.2 g/100 g body weight, P = 0.006) and serum urea nitrogen (SUN) (9.6 +/- 0.6 vs. 11.9 +/- 0.6 mmol/L, P = 0.009), whereas in young pcy mice it reduced renal fibrosis volumes (0.44 +/- 0.04 vs. 0.62 +/- 0.04 mL/kg body weight, P < 0.0001). FO feeding in young pcy mice mitigated the detrimental effects of high fat on fibrosis while not altering kidney size, function, and oxidative damage when compared with the CO-fed mice. In contrast, DO- compared with CO-fed mice had higher kidney weights (2.64 +/- 0.07 vs. 2.24 +/- 0.08 g/100 g body weight, P = 0.005), SUN (9.4 +/- 0.57 vs. 7.0 +/- 0.62 mmol/L, P < 0.0001), and cyst volumes (7.9 +/- 0.28 vs. 6.2 +/- 0.30 mL/kg body weight, P < 0.0001) and similar levels of oxidative damage and fibrosis. The FA compositions of the diets were reflected in the kidneys: 18:2n-6, 18:3n-3, and 22:6n-3 were the highest in the CO, FO, and DO diets, respectively. Dietary effects on kidney disease progression were similar in males and females. A low-fat diet slows progression of renal injury in male and female pcy mice, consistent with findings in the male Han:SPRD-cy rat. Dietary fat type also influenced renal injury, with flaxseed oil diets rich in 18:3n-3 slowing early fibrosis progression compared with diets rich in 18:2n-6 or in 22:6n-3.

Cytosolic phospholipase A2 (cPLA2), cyclooxygenase-1 (COX-1), and cyclooxygenase-2 (COX-2) regulate the formation of physiologically active prostaglandins, the production of which is known to be elevated in several renal disorders. We studied the relevance of these enzymes in polycystic kidney disease (PKD) by using two models of the disease: a model in which decline in renal function begins in adulthood (CD1-pcy/pcy mouse) and one in which it occurs early, during growth (Han:SPRD-cy rat). Immunoblotting analyses of cytosolic and particulate kidney fractions revealed that cPLA2 levels are significantly higher (by 34-131%) in the latter stages of the disease in both models. Renal COX enzymes were found only in the particulate fractions, with COX-1 87% higher in 6-month-old CD1-pcy/pcy mice compared with normal controls, and 110% higher in male 70-day-old Han:SPRD-cy rats with cystic kidneys compared with controls. Renal COX-2 was detected only in the rats and was 58% lower in diseased kidneys of 70-day-old male Han:SPRD-cy rats, indicating that cPLA2 is coupled to COX-1 in the kidney. The altered levels of these eicosanoid-regulating enzymes has implications for the use of NSAIDS and specific COX inhibitors in individuals with this disorder.

Dietary fish oils containing (n-3) fatty acids can modulate renal inflammatory injury. We previously demonstrated that a high fat (HF) diet worsens early renal disease progression in the Han:SPRD-cy rat model of polycystic kidney disease (PKD). Therefore, using HF (20 g/100 g diet) and low fat (LF; 5 g/100 g diet) diets, we compared the effects of menhaden oil (MO), soybean oil (SO) and cottonseed oil (CO) on renal function and histology in male Han:SPRD-cy rats fed the diets for 6 wk in the early stages of renal disease. Overall, rats fed HF compared with those fed LF diets had larger kidneys, more renal fibrosis and lower creatinine clearance (main effects of fat level). Rats fed MO rather than CO and SO diets had significantly lower kidney weights, kidney water content, cyst volumes and serum cholesterol and triglyceride concentrations (main effects of fat type). Rats fed MO diets also had less renal fibrosis than those fed CO diets, but the least fibrosis was in rats fed SO diets. Analysis of simple effects (due to interactions between fat level and type) revealed that HF diets increased renal inflammation in rats fed CO diets, but reduced inflammation was present in those fed SO and MO diets; HF diets also increased compared with LF diets serum urea nitrogen concentrations in rats fed the MO and CO diets, but not the SO diet. These results confirm that high dietary fat worsens early disease progression in this model of renal disease, and further demonstrate that diets with oils containing (n-3) fatty acids ameliorate some of the detrimental effects of a high fat diet.