Adipocyte lipid storage and adipokine production are modulated by lipoxygenase-derived oxylipins generated from 18-carbon fatty acids

Differential Modulation by Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) of Mesenteric Fat and Macrophages and T Cells in Adipose Tissue of Obese fa/fa Zucker Rats

Polyunsaturated fatty acids (PUFAs) can alter adipose tissue function; however, the relative effects of plant and marine n3-PUFAs are less clear. Our objective was to directly compare the n3-PUFAs, plant-based α-linolenic acid (ALA) in flaxseed oil, and marine-based eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in high-purity oils versus n6-PUFA containing linoleic acid (LA) for their effects on the adipose tissue and oral glucose tolerance of obese rats. Male fa/fa Zucker rats were assigned to faALA, faEPA, faDHA, and faLA groups and compared to baseline fa/fa rats (faBASE) and lean Zucker rats (lnLA). After 8 weeks, faEPA and faDHA had 11-14% lower body weight than faLA. The oral glucose tolerance and total body fat were unchanged, but faEPA had less mesenteric fat. faEPA and faDHA had fewer large adipocytes compared to faLA and faALA. EPA reduced macrophages in the adipose tissue of fa/fa rats compared to ALA and DHA, while faLA had the greatest macrophage infiltration. DHA decreased (~10-fold) T-cell infiltration compared to faBASE and faEPA, whereas faALA and faLA had an ~40% increase. The n3-PUFA diets attenuated tumour necrosis factor-α in adipose tissue compared to faBASE, while it was increased by LA in both genotypes. In conclusion, EPA and DHA target different aspects of inflammation in adipose tissue.

Oxylipins biosynthesis and the regulation of bovine postpartum inflammation

Uncontrolled or dysregulated inflammation has adverse effects on the reproduction, production and health of animals, and is a major pathological cause of increased incidence and severity of infectious and metabolic diseases. To achieve successful transition from a non-lactation pregnant state to a non-pregnant lactation state, drastic metabolic and endocrine alteration have taken place in dairy cows during the periparturient period. These physiological changes, coupled with decreased dry matter intake near calving and sudden change of diet composition after calving, have the potential to disrupt the delicate balance between pro- and anti-inflammation, resulting in a disordered or excessive inflammatory response. In addition to cytokines and other immunoregulatory factors, most oxylipins formed from polyunsaturated fatty acids (PUFAs) via enzymatic and nonenzymatic oxygenation pathways have pro- or anti-inflammatory properties and play a pivotal role in the onset, development and resolution of inflammation. However, little attention has been paid to the possibility that oxylipins could function as endogenous immunomodulating agents. This review will provide a detailed overview of the main oxylipins derived from different PUFAs and discuss the regulatory role that oxylipins play in the postpartum inflammatory response in dairy cows. Based on the current research, much remains to be illuminated in this emerging field. Understanding the role that oxylipins play in the control of postpartum inflammation and inflammatory-based disease may improve our ability to prevent transition disorders via Management, pharmacological, genetic selection and dietary intervention strategies.

Metabolic adaptations in severe obesity: Insights from circulating oxylipins before and after weight loss

BACKGROUND

The relationship between lipid mediators and severe obesity remains unclear. Our study investigates the impact of severe obesity on plasma concentrations of oxylipins and fatty acids and explores the consequences of weight loss.

METHODS

In the clinical trial identifier NCT05554224 study, 116 patients with severe obesity and 63 overweight/obese healthy controls matched for age and sex (≈2:1) provided plasma. To assess the effect of surgically induced weight loss, we requested paired plasma samples from 44 patients undergoing laparoscopic sleeve gastrectomy one year after the procedure. Oxylipins were measured using ultra-high-pressure liquid chromatography coupled to a triple quadrupole mass spectrometer via semi-targeted lipidomics. Cytokines and markers of interorgan crosstalk were measured using enzyme-linked immunosorbent assays.

RESULTS

We observed significantly elevated levels of circulating fatty acids and oxylipins in patients with severe obesity compared to their metabolically healthier overweight/obese counterparts. Our findings indicated that sex and liver disease were not confounding factors, but we observed weak correlations in plasma with circulating adipokines, suggesting the influence of adipose tissue. Importantly, while weight loss restored the balance in circulating fatty acids, it did not fully normalize the oxylipin profile. Before surgery, oxylipins derived from lipoxygenase activity, such as 12-HETE, 11-HDoHE, 14-HDoHE, and 12-HEPE, were predominant. However, one year following laparoscopic sleeve gastrectomy, we observed a complex shift in the oxylipin profile, favoring species from the cyclooxygenase pathway, particularly proinflammatory prostanoids like TXB2, PGE2, PGD2, and 12-HHTrE. This transformation appears to be linked to a reduction in adiposity, underscoring the role of lipid turnover in the development of metabolic disorders associated with severe obesity.

CONCLUSIONS

Despite the reduction in fatty acid levels associated with weight loss, the oxylipin profile shifts towards a predominance of more proinflammatory species. These observations underscore the significance of seeking mechanistic approaches to address severe obesity and emphasize the importance of closely monitoring the metabolic adaptations after weight loss.

Lipidomics Profiling of the Linoleic Acid Metabolites After Whole-Body Vibration in Humans

Bioactive lipids have been identified as dynamic signaling lipid mediators (LMs). These fats have the ability to activate responses and control bodily functions either directly or indirectly. Linoleic Acid (LA) and Alpha Linoleic Acid (ALA) are types of omega 3 fatty acids that possess inflammatory properties and promote resolution of inflammation either through their own actions or through their metabolites known as oxylipins. In this chapter, we provide an explanation of a method that combines chromatography with tandem mass spectroscopy (LC MS/MS) to identify and measure all the metabolites derived from LA and ALA. Additionally, we employed the described methodology to analyze human serum samples obtained before and after whole-body vibration exercise training. The results indicated an increase in some of the LA and ALA LMs that have beneficial effects in regulating the cardiovascular system.

Oxylipin secretion by human CD3+ T lymphocytes in vitro is modified by the exogenous essential fatty acid ratio and life stage

Immune function changes across the life stages; for example, senior adults exhibit a tendency towards a weaker cell-mediated immune response and a stronger inflammatory response than younger adults. This might be partly mediated by changes in oxylipin synthesis across the life course. Oxylipins are oxidation products of polyunsaturated fatty acids (PUFAs) that modulate immune function and inflammation. A number of PUFAs are precursors to oxylipins, including the essential fatty acids (EFAs) linoleic acid (LA) and α-linolenic acid (ALA). LA and ALA are also substrates for synthesis of longer chain PUFAs. Studies with stable isotopes have shown that the relative amounts of LA and ALA can influence their partitioning by T lymphocytes between conversion to longer chain PUFAs and to oxylipins. It is not known whether the relative availability of EFA substrates influences the overall pattern of oxylipin secretion by human T cells or if this changes across the life stages. To address this, the oxylipin profile was determined in supernatants from resting and mitogen activated human CD3+ T cell cultures incubated in medium containing an EFA ratio of either 5:1 or 8:1 (LA : ALA). Furthermore, oxylipin profiles in supernatants of T cells from three life stages, namely fetal (derived from umbilical cord blood), adults and seniors, treated with the 5:1 EFA ratio were determined. The extracellular oxylipin profiles were affected more by the EFA ratio than mitogen stimulation such that n-3 PUFA-derived oxylipin concentrations were higher with the 5:1 EFA ratio than the 8:1 ratio, possibly due to PUFA precursor competition for lipoxygenases. 47 oxylipin species were measured in all cell culture supernatants. Extracellular oxylipin concentrations were generally higher for fetal T cells than for T cells from adult and senior donors, although the composition of oxylipins was similar across the life stages. The contribution of oxylipins towards an immunological phenotype might be due to the capacity of T cells to synthesize oxylipins rather than the nature of the oxylipins produced.

The Role of α-Linolenic Acid and Its Oxylipins in Human Cardiovascular Diseases

α-linolenic acid (ALA) is an essential C-18 n-3 polyunsaturated fatty acid (PUFA), which can be elongated to longer n-3 PUFAs, such as eicosapentaenoic acid (EPA). These long-chain n-3 PUFAs have anti-inflammatory and pro-resolution effects either directly or through their oxylipin metabolites. However, there is evidence that the conversion of ALA to the long-chain PUFAs is limited. On the other hand, there is evidence in humans that supplementation of ALA in the diet is associated with an improved lipid profile, a reduction in the inflammatory biomarker C-reactive protein (CRP) and a reduction in cardiovascular diseases (CVDs) and all-cause mortality. Studies investigating the cellular mechanism for these beneficial effects showed that ALA is metabolized to oxylipins through the Lipoxygenase (LOX), the Cyclooxygenase (COX) and the Cytochrome P450 (CYP450) pathways, leading to hydroperoxy-, epoxy-, mono- and dihydroxylated oxylipins. In several mouse and cell models, it has been shown that ALA and some of its oxylipins, including 9- and 13-hydroxy-octadecatrienoic acids (9-HOTrE and 13-HOTrE), have immunomodulating effects. Taken together, the current literature suggests a beneficial role for diets rich in ALA in human CVDs, however, it is not always clear whether the described effects are attributable to ALA, its oxylipins or other substances present in the supplemented diets.

Functional Characterization of Transgenic Mice Overexpressing Human 15-Lipoxygenase-1 (ALOX15) under the Control of the aP2 Promoter

Arachidonic acid lipoxygenases (ALOX) have been implicated in the pathogenesis of inflammatory, hyperproliferative, neurodegenerative, and metabolic diseases, but the physiological function of ALOX15 still remains a matter of discussion. To contribute to this discussion, we created transgenic mice (aP2-ALOX15 mice) expressing human ALOX15 under the control of the aP2 (adipocyte fatty acid binding protein 2) promoter, which directs expression of the transgene to mesenchymal cells. Fluorescence in situ hybridization and whole-genome sequencing indicated transgene insertion into the E1-2 region of chromosome 2. The transgene was highly expressed in adipocytes, bone marrow cells, and peritoneal macrophages, and ex vivo activity assays proved the catalytic activity of the transgenic enzyme. LC-MS/MS-based plasma oxylipidome analyses of the aP2-ALOX15 mice suggested in vivo activity of the transgenic enzyme. The aP2-ALOX15 mice were viable, could reproduce normally, and did not show major phenotypic alterations when compared with wildtype control animals. However, they exhibited gender-specific differences with wildtype controls when their body-weight kinetics were evaluated during adolescence and early adulthood. The aP2-ALOX15 mice characterized here can now be used for gain-of-function studies evaluating the biological role of ALOX15 in adipose tissue and hematopoietic cells.

Detoxification Cytochrome P450s (CYPs) in Families 1-3 Produce Functional Oxylipins from Polyunsaturated Fatty Acids

This manuscript reviews the CYP-mediated production of oxylipins and the current known function of these diverse set of oxylipins with emphasis on the detoxification CYPs in families 1-3. Our knowledge of oxylipin function has greatly increased over the past 3-7 years with new theories on stability and function. This includes a significant amount of new information on oxylipins produced from linoleic acid (LA) and the omega-3 PUFA-derived oxylipins such as α-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). However, there is still a lack of knowledge regarding the primary CYP responsible for producing specific oxylipins, and a lack of mechanistic insight for some clinical associations between outcomes and oxylipin levels. In addition, the role of CYPs in the production of oxylipins as signaling molecules for obesity, energy utilization, and development have increased greatly with potential interactions between diet, endocrinology, and pharmacology/toxicology due to nuclear receptor mediated CYP induction, CYP inhibition, and receptor interactions/crosstalk. The potential for diet-diet and diet-drug/chemical interactions is high given that these promiscuous CYPs metabolize a plethora of different endogenous and exogenous chemicals.

Effects of Coix Seed Oil on High Fat Diet-Induced Obesity and Dyslipidemia

Dietary intervention is becoming more popular as a way to improve lipid metabolism and reduce the prevalence of diet-related chronic disorders. We evaluated the effects of several dietary oils on body weight, fat mass, liver weight, and tumor necrosis factor in obese mice given a high-fat diet (HFD) to discover if coix seed oil (CSO) had an anti-obesity impact. As compared to other dietary fats, CSO treatment considerably lowered body weight and liver index, successfully sup-pressed total cholesterol and triglyceride content, and raised liver lipid deposition and lipid metabolism problem induced by high fat intake. Furthermore, gas chromatography research revealed that CSO extracted by supercritical fluid, with 64% being CSO extracted by supercritical fluid, and the greatest amounts of capric acids and lauric acids being 35.28% and 22.21%, respectively. CSO contained a high content of medium-chain fatty acids and was able to modify hepatic fatty acid metabolism and lipid levels in HFD-induced obese mice. According to the results, CSO has the potential to replace dietary lipids as a promising functional lipid in the prevention of met-abolish disorders.

Linoleate-Rich Safflower Oil Diet Increases Linoleate-Derived Bioactive Lipid Mediators in Plasma, and Brown and White Adipose Depots of Healthy Mice

Polyunsaturated fats are energy substrates and precursors to the biosynthesis of lipid mediators of cellular processes. Adipose tissue not only provides energy storage, but influences whole-body energy metabolism through endocrine functions. How diet influences adipose-lipid mediator balance may have broad impacts on energy metabolism. To determine how dietary lipid sources modulate brown and white adipose tissue and plasma lipid mediators, mice were fed low-fat (15% kcal fat) isocaloric diets, containing either palm oil (POLF) or linoleate-rich safflower oil (SOLF). Baseline and post body weight, adiposity, and 2-week and post fasting blood glucose were measured and lipid mediators were profiled in plasma, and inguinal white and interscapular brown adipose tissues. We identified over 30 species of altered lipid mediators between diets and found that these changes were unique to each tissue. We identified changes to lipid mediators with known functional roles in the regulation of adipose tissue expansion and function, and found that there was a relationship between the average fold difference in lipid mediators between brown adipose tissue and plasma in mice consuming the SOLF diet. Our findings emphasize that even with a low-fat diet, dietary fat quality has a profound effect on lipid mediator profiles in adipose tissues and plasma.

Molecular pathways behind acquired obesity: Adipose tissue and skeletal muscle multiomics in monozygotic twin pairs discordant for BMI

Tissue-specific mechanisms prompting obesity-related development complications in humans remain unclear. We apply multiomics analyses of subcutaneous adipose tissue and skeletal muscle to examine the effects of acquired obesity among 49 BMI-discordant monozygotic twin pairs. Overall, adipose tissue appears to be more affected by excess body weight than skeletal muscle. In heavier co-twins, we observe a transcriptional pattern of downregulated mitochondrial pathways in both tissues and upregulated inflammatory pathways in adipose tissue. In adipose tissue, heavier co-twins exhibit lower creatine levels; in skeletal muscle, glycolysis- and redox stress-related protein and metabolite levels remain higher. Furthermore, metabolomics analyses in both tissues reveal that several proinflammatory lipids are higher and six of the same lipid derivatives are lower in acquired obesity. Finally, in adipose tissue, but not in skeletal muscle, mitochondrial downregulation and upregulated inflammation are associated with a fatty liver, insulin resistance, and dyslipidemia, suggesting that adipose tissue dominates in acquired obesity.

Multiomics analyses of adipose tissue and skeletal muscle in BMI-discordant twins

Excess body weight downregulates mitochondrial pathways in both tissues

Excess body weight upregulates proinflammatory pathways in both tissues

Adipose tissue alterations are associated with metabolic health in acquired obesity

Linoleic Acid-Rich Oil Supplementation Increases Total and High-Molecular-Weight Adiponectin and Alters Plasma Oxylipins in Postmenopausal Women with Metabolic Syndrome

BACKGROUND

The onset of menopause increases the risk of metabolic syndrome (MetS). Adiponectin is an adipokine associated with insulin sensitivity that is lower in people with MetS. Supplementing diets with linoleic acid (LA)-rich oil increased adiponectin concentrations and improved glucose control in women with type 2 diabetes. The effect of LA on adipokines, especially total and the bioactive form of adiponectin, high-molecular-weight (HMW) adiponectin, in women with MetS is unknown.

OBJECTIVES

The aim of this study was to explore the effect of supplementation of the diet with an oil rich in LA on adipokines in women with MetS. The effect of the LA-rich oil (LA-oil) on oxylipins, key metabolites that may influence inflammation and metabolism, was also explored.

METHODS

In this open-label single-arm pilot study, 18 postmenopausal nondiabetic women with MetS enrolled in a 2-phase study were instructed to consume LA-rich vegetable oil (10 mL/d) as part of their habitual diets. Women consumed an oleic acid-rich oil (OA-oil) for 4 wk followed by an LA-oil for 16 wk. Fasting concentrations of adipokines, fatty acids, oxylipins, and markers of glycemia and inflammation were measured.

RESULTS

After 4 wk of OA-oil consumption, fasting glucose and total adiponectin concentrations decreased whereas fasting C-reactive protein increased. After 16 wk of LA-oil supplementation total and HMW adiponectin and plasma oxylipins increased. Markers of inflammation and glycemia were unchanged after LA-oil consumption.

CONCLUSIONS

Supplementation with LA-oil increased total and HMW adiponectin concentrations and altered plasma oxylipin profiles. Larger studies are needed to elucidate the links between these changes and MetS.This trial was registered at clinicaltrials.gov as NCT02063165.

The effect of western diet on mice brain lipid composition

Background

The appropriate fatty acids composition of brain lipids is critical for functioning of this organ. The alterations of brain fatty acids composition may lead to neurological and neurodegenerative diseases.

Methods

The aim of this work was to evaluate the effect of western diet containing high fat content on fatty acid composition of brain lipids. In this study we used mice fed high fat diet (HFD) for 19 weeks. Brain lipids were separated by SPE extraction and fatty acid composition in chow, mice serum, brain and other tissues was analyzed by GC-MS method.

Results

The body weight and adipose tissue weigh of mice after HFD increased significantly. The concentrations of most of fatty acids in serum of mice after HFD increased, due to their higher delivery from food. Unexpectedly the serum eicosapentaenoic acid (EPA) concentration was lower in mice after HFD than in controls. Also the brain, and other tissue EPA content was lower. Among studied groups of brain lipids EPA was significantly decreased in phospholipids and sphingolipids.

Conclusions

Considering important role of brain EPA including maintaining of appropriate composition of cell membrane lipids and anti-inflammatory properties we conclude that decrease of brain EPA after western diet may result in impaired brain function.

Adipose tissue oxylipin profiles vary by anatomical site and are altered by dietary linoleic acid in rats

Dietary PUFA and their effects on adipose tissue have been well studied, but oxylipins, the oxygenated metabolites of PUFA, have been sparsely studied in adipose tissue. To determine the oxylipin profile and to examine their potential importance in various adipose sites, female and male rats were provided control, high linoleic acid (LA), or high LA and high α-linolenic acid (LA + ALA) diets for six weeks. Analysis of gonadal (GAT), mesenteric (MAT), perirenal (PAT), and subcutaneous adipose tissues (SAT) revealed higher numbers of oxylipins in MAT and SAT, primarily due to 20-22 carbon cytochrome P450 oxylipins, as well as metabolites of cyclooxygenase derived oxylipins. LA oxylipins made up 75-96% of the total oxylipin mass and largely determined the total relative amounts between depots (GAT > MAT > PAT > SAT). However, when the two most abundant LA oxylipins (TriHOMEs) were excluded, MAT had the highest mass of oxylipins and exhibited the most sex differences. These differences existed despite comparable PUFA composition between depots. Dietary LA increased oxylipins derived from n-6 PUFA, and the addition of ALA generally returned n-6 PUFA oxylipins to levels similar to control and elevated some n-3 oxylipins. These data on oxylipin profiles in adipose depots from different anatomical sites and the effects of diet and sex provide fundamental knowledge that will aid future studies investigating the physiological effects of adipose tissue.

Hepatic transcriptome of the euryhaline teleost Japanese seabass (Lateolabrax japonicus) fed diets characterized by α-linolenic acid or linoleic acid

To investigate the different effects of dietary α-linolenic acid (ALA) and linoleic acid (LA) on the euryhaline fish Japanese seabass, a feeding trial followed by hepatic transcriptome assay was conducted. Two experimental diets containing 10% LA-rich sunflower seed oil (diet LA) or 10% ALA-rich perilla oil (diet ALA) were used in the feeding trial. LA and ALA in diets were characteristically incorporated into fish tissues while no significant difference was observed in growth performance and body proximate composition between groups LA and ALA. Compared to LA, ALA up-regulated transcription of 49 unigenes and down-regulated those of 311 unigenes. Quantitative RT-PCR studies on eight lipid metabolism-related genes and seven randomly selected genes were conducted to validate the transcriptomic results. Lipid metabolism-related genes ApoA1, ApoA4, ApoE, FABP1, FABP3, FABP4, FATP6, and DGAT1, as well as ribosomal proteins L9e, L13e, and S4e, were transcriptionally down-regulated by ALA. The differentially expressed genes (DEGs) were primarily enriched in Gene Ontology terms such as Lipid transport, Protein metabolic process, and Ribosome biogenesis, as well as in KEGG pathways such as Complement and coagulation cascades and Ribosome. The Protein-Protein Interaction (PPI) network based on the peptide biosynthesis-related DEGs showed that ribosomal proteins such as SAe, L4e, S4e, L15e, L9e, and L13Ae had high betweenness centrality in the dietary regulation of peptide biosynthetic processes. In conclusion, under the present experimental conditions, a high level of dietary α-linolenic acid tended to suppress lipid transport and protein biosynthetic processes in the liver of Japanese seabass at the gene expression level.

Lipoxygenases and Lipoxygenase Products in Marine Diatoms

Marine diatoms negatively affect reproduction and later larval development of dominant zooplankton grazers such as copepods, thereby lowering the recruitment of the next generations of these small crustaceans that are a major food source for larval fish species. The phenomenon has been explained in terms of chemical defense due to grazer-induced synthesis of oxylipins, lipoxygenase-derived oxygenated fatty acid derivatives. Since this first report, studies about diatom oxylipins have multiplied and broadened toward other aspects concerning bloom dynamics, cell growth, and cell differentiation. Diatom oxylipins embrace a number of diverse structures that are recognized as chemical signals in ecological and physiological processes in many other organisms. In diatoms, the most studied examples include polyunsaturated aldehydes (PUAs) and nonvolatile oxylipins (NVOs). The purpose of this chapter is to provide the analytical tools to deal with identification, analysis and biosynthesis of these compounds. Emphasis is given to identification of the enzymatic steps and characterization of the species-specific lipoxygenases even in absence of the availability of molecular information.

Anti-inflammatory effects of α-linolenic acid in M1-like macrophages are associated with enhanced production of oxylipins from α-linolenic and linoleic acid

Chronic inflammation, mediated in large part by proinflammatory macrophage populations, contributes directly to the induction and perpetuation of metabolic diseases, including obesity, insulin resistance and type 2 diabetes. Polyunsaturated fatty acids (PUFAs) can have profound effects on inflammation through the formation of bioactive oxygenated metabolites called oxylipins. The objective of this study was to determine if exposure to the dietary omega-3 PUFA α-linolenic acid (ALA) can dampen the inflammatory properties of classically activated (M1-like) macrophages derived from the human THP-1 cell line and to examine the accompanying alterations in oxylipin secretion. We find that ALA treatment leads to a reduction in lipopolysaccharide (LPS)-induced interleukin (IL)-1β, IL-6 and tumor necrosis factor-α production. Although ALA is known to be converted to longer-chain PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), DHA oxylipins were reduced overall by ALA treatment, as was LPS-induced secretion of EPA oxylipins. In contrast, we observed profound increases in oxylipins directly derived from ALA. Lipoxygenase products of linoleic acid were also dramatically increased, and LPS-induced production of AA oxylipins, particularly prostaglandin D2, was reduced. These results suggest that ALA may act to dampen the inflammatory phenotype of M1-like macrophages by a unique set of mechanisms distinct from those used by the long-chain omega-3 fatty acids EPA and DHA. Thus, there is strong rationale for investigating the functions of ALA oxylipins and lesser-known LA oxylipins since they hold promise as anti-inflammatory agents.

Distinct effects of dietary ALA, EPA and DHA on rat adipose oxylipins vary by depot location and sex

Dietary EPA and DHA given together alter oxylipins in adipose tissue. To compare the separate effects of individual dietary n-3 PUFA on oxylipins in different adipose depots (gonadal, mesenteric, perirenal, subcutaneous) in males and females, rats were provided diets containing higher levels of α-linolenic acid (ALA), EPA or DHA. Each n-3 PUFA enhanced its respective oxylipins the most, while effects on other n-3 oxylipins varied. For example: in perirenal and subcutaneous depots, more DHA oxylipins were higher with dietary ALA than with EPA; dietary EPA uniquely decreased 14-hydroxy-docosahexaenoic acid, in contrast to increasing many other DHA oxylipins. The n-3 PUFAs also reduced oxylipins from n-6 PUFAs in order of effectiveness: DHA > EPA > ALA. Diet by sex interactions in all depots except the perirenal depot resulted in higher oxylipins in males given DHA, and higher oxylipins in females given the other diets. Diet and sex effects on oxylipins did not necessarily reflect effects on either their tissue phospholipid or neutral lipid PUFA precursors. These varying diet and sex effects on oxylipins in the different adipose sites indicate that they may have distinct effects on adipose function.

Chemopreventive and Chemotherapeutic Effects of Fish Oil derived Omega-3 Polyunsaturated Fatty Acids on Colon Carcinogenesis

Colorectal cancer is the third most common cause of cancer related death in the world. Multiple lines of evidence suggest that there is an association between consumption of dietary fat and colon cancer risk. Not only the amount but also the type and the ratio of fatty acids comprising dietary fats consumed have been implicated in the etiology and pathogenesis of colon cancer. Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been known to inhibit development of colon cancer by downregulating the expression of genes involved in colon carcinogenesis and also by altering the membrane lipid composition. Data from laboratory, epidemiological, and clinical studies substantiate the beneficial role of n-3 PUFAs in preventing colitis and subsequent development of colon cancer. In addition, recent studies suggest that some n-3 PUFAs can be effective as an adjuvant with chemotherapeutic agents and other natural anticancer compounds in the management of colon cancer. In this review, we discuss chemopreventive and therapeutic effects of fish oil derived long chain n-3 PUFAs, particularly EPA and DHA, with focus on synergetic effects of which they exert when combined with chemotherapeutic agents and other natural compounds.