Effect of age and dietary fat (fish, corn and coconut oils) on tocopherol status of C57BL/6Nia mice

Dysbiotic lung microbial communities of neonates from allergic mothers confer neonate responsiveness to suboptimal allergen

In humans and animals, offspring of allergic mothers have increased responsiveness to allergens. This is blocked in mice by maternal supplementation with α-tocopherol (αT). Also, adults and children with allergic asthma have airway microbiome dysbiosis with increased Proteobacteria and may have decreased Bacteroidota. It is not known whether αT alters neonate development of lung microbiome dysbiosis or whether neonate lung dysbiosis modifies development of allergy. To address this, the bronchoalveolar lavage was analyzed by 16S rRNA gene analysis (bacterial microbiome) from pups of allergic and non-allergic mothers with a basal diet or αT-supplemented diet. Before and after allergen challenge, pups of allergic mothers had dysbiosis in lung microbial composition with increased Proteobacteria and decreased Bacteroidota and this was blocked by αT supplementation. We determined whether intratracheal transfer of pup lung dysbiotic microbial communities modifies the development of allergy in recipient pups early in life. Interestingly, transfer of dysbiotic lung microbial communities from neonates of allergic mothers to neonates of non-allergic mothers was sufficient to confer responsiveness to allergen in the recipient pups. In contrast, neonates of allergic mothers were not protected from development of allergy by transfer of donor lung microbial communities from either neonates of non-allergic mothers or neonates of αT-supplemented allergic mothers. These data suggest that the dysbiotic lung microbiota is dominant and sufficient for enhanced neonate responsiveness to allergen. Importantly, infants within the INHANCE cohort with an anti-inflammatory profile of tocopherol isoforms had an altered microbiome composition compared to infants with a pro-inflammatory profile of tocopherol isoforms. These data may inform design of future studies for approaches in the prevention or intervention in asthma and allergic disease early in life.

Asthma, allergy and vitamin E: Current and future perspectives

Asthma and allergic disease result from interactions of environmental exposures and genetics. Vitamin E is one environmental factor that can modify development of allergy early in life and modify responses to allergen after allergen sensitization. Seemingly varied outcomes from vitamin E are consistent with the differential functions of the isoforms of vitamin E. Mechanistic studies demonstrate that the vitamin E isoforms α-tocopherol and γ-tocopherol have opposite functions in regulation of allergic inflammation and development of allergic disease, with α-tocopherol having anti-inflammatory functions and γ-tocopherol having pro-inflammatory functions in allergy and asthma. Moreover, global differences in prevalence of asthma by country may be a result, at least in part, of differences in consumption of these two isoforms of tocopherols. It is critical in clinical and animal studies that measurements of the isoforms of tocopherols be determined in vehicles for the treatments, and in the plasma and/or tissues before and after intervention. As allergic inflammation is modifiable by tocopherol isoforms, differential regulation by tocopherol isoforms provide a foundation for development of interventions to improve lung function in disease and raise the possibility of early life dietary interventions to limit the development of lung disease.

γ-Tocopherol supplementation of allergic female mice augments development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

γ-Tocopherol increases responses to allergen challenge in allergic adult mice, but it is not known whether γ-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether γ-tocopherol augments development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with γ-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to allergen challenge. The γ-tocopherol supplementation of allergic female mice increased the numbers of eosinophils twofold in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also about a twofold increase in pup lung CD11b(+) subsets of CD11c(+) dendritic cells and in numbers of these dendritic cells expressing the transcription factor IRF4. There was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with γ-tocopherol increased the number of fetal liver CD11b(+)CD11c(+) dendritic cells twofold in utero. In the pups, γ-tocopherol increased lung expression of the inflammatory mediators CCL11, amphiregulin, activin A, and IL-5. In conclusion, maternal supplementation with γ-tocopherol increased fetal development of subsets of dendritic cells that are critical for allergic responses and increased development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with γ-tocopherol in prenatal vitamins.

The α-tocopherol form of vitamin E reverses age-associated susceptibility to streptococcus pneumoniae lung infection by modulating pulmonary neutrophil recruitment

Streptococcus pneumoniae infections are an important cause of morbidity and mortality in older patients. Uncontrolled neutrophil-driven pulmonary inflammation exacerbates this disease. To test whether the α-tocopherol (α-Toc) form of vitamin E, a regulator of immunity, can modulate neutrophil responses as a preventive strategy to mitigate the age-associated decline in resistance to S. pneumoniae, young (4 mo) and old (22-24 mo) C57BL/6 mice were fed a diet containing 30-PPM (control) or 500-PPM (supplemented) α-Toc for 4 wk and intratracheally infected with S. pneumoniae. Aged mice fed a control diet were exquisitely more susceptible to S. pneumoniae than young mice. At 2 d postinfection, aged mice suffered 1000-fold higher pulmonary bacterial burden, 2.2-fold higher levels of neutrophil recruitment to the lung, and a 2.25-fold higher rate of lethal septicemia. Strikingly, α-Toc supplementation of aged mice resulted in a 1000-fold lower bacterial lung burden and full control of infection. This α-Toc-induced resistance to pneumococcal challenge was associated with a 2-fold fewer pulmonary neutrophils, a level comparable to S. pneumoniae-challenged, conventionally fed young mice. α-Toc directly inhibited neutrophil egress across epithelial cell monolayers in vitro in response to pneumococci or hepoxilin-A3, an eicosanoid required for pneumococcus-elicited neutrophil trans-epithelial migration. α-Toc altered expression of multiple epithelial and neutrophil adhesion molecules involved in migration, including CD55, CD47, CD18/CD11b, and ICAM-1. These findings suggest that α-Toc enhances resistance of aged mice to bacterial pneumonia by modulating the innate immune response, a finding that has potential clinical significance in combating infection in aged individuals through nutritional intervention.

α-Tocopherol supplementation of allergic female mice inhibits development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

α-Tocopherol blocks responses to allergen challenge in allergic adult mice, but it is not known whether α-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether α-tocopherol blocked development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with α-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to the allergen challenge, and α-tocopherol supplementation of allergic female mice resulted in a dose-dependent reduction in eosinophils in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also a reduction in pup lung CD11b(+) dendritic cell subsets that are critical to development of allergic responses, but there was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with α-tocopherol reduced the number of fetal liver CD11b(+) dendritic cells in utero. In the pups, there was reduced allergen-induced lung mRNA expression of IL-4, IL-33, TSLP, CCL11, and CCL24. Cross-fostering pups at the time of birth demonstrated that α-tocopherol had a regulatory function in utero. In conclusion, maternal supplementation with α-tocopherol reduced fetal development of subsets of dendritic cells that are critical for allergic responses and reduced development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with α-tocopherol.

Vitamin E isoforms as modulators of lung inflammation

Asthma and allergic diseases are complex conditions caused by a combination of genetic and environmental factors. Clinical studies suggest a number of protective dietary factors for asthma, including vitamin E. However, studies of vitamin E in allergy commonly result in seemingly conflicting outcomes. Recent work indicates that allergic inflammation is inhibited by supplementation with the purified natural vitamin E isoform α-tocopherol but elevated by the isoform γ-tocopherol when administered at physiological tissue concentrations. In this review, we discuss opposing regulatory effects of α-tocopherol and γ-tocopherol on allergic lung inflammation in clinical trials and in animal studies. A better understanding of the differential regulation of inflammation by isoforms of vitamin E provides a basis towards the design of clinical studies and diets that would effectively modulate inflammatory pathways in lung disease.

Perturbation of cellular immune functions in cigarette smokers and protection by palm oil vitamin E supplementation

Background

Cigarette smoke contains free radicals and an have adverse effect to the immune system. Supplementation of palm oil vitamin E (palmvitee), is known has antioxidant properties is thought to be beneficial for system immune protection against free radicals activity. The objective of the study was to determine the effect of palmvitee supplementation on immune response in smokers.

Methods

This study involved a group of smokers and nonsmokers who received 200 mg/day palmvitee and placebo for the control group. Blood samples were taken at 0, 12 and 24 weeks of supplementation. Plasma tocopherol and tocotrienol were determined by HPLC, lymphocyte proliferation by lymphocyte transformation test (LTT) and enumeration of lymphocytes T and B cells by flow cytometry. Statistical analysis was performed by Mann–Whitney U-test for non-parametric data distribution and correlation among the variables was examined by Spearman.

Results

Plasma tocopherol and tocotrienol were increased in vitamin E supplemented group as compared to placebo group. Urine cotinine levels and serum α₁-antitrypsin were significantly higher in smokers compared to nonsmokers. Lymphocyte proliferation induced by PHA showed an increasing trend with palmvitee supplementation in both smokers and nonsmokers. Natural killer cells were decreased; CD4⁺ cells and B cells were increased in smokers compared to nonsmokers but were unaffected with vitamin E supplementation except in the percentage of B cells which were increased in nonsmokers supplemented palmvitee compared to placebo. CD4⁺/CD8⁺ ratio was increased in smokers compared to nonsmokers. The high TWBC count observed in smokers correlated with the increased CD4⁺ and B cells.

Conclusions

Smoking caused alterations in certain immune parameters and palmvitee supplementation tended to cause an increase in lymphocytes transformation test but had no effect on CD3⁺, CD4⁺, CD8⁺, NK cells and B cells except B cells percentage in nonsmokers.

Isoforms of Vitamin E Differentially Regulate PKC α and Inflammation: A Review

Vitamin E regulation of disease has been extensively studied but most studies focus on the α-tocopherol isoform of vitamin E. These reports indicate contradictory outcomes for anti-inflammatory functions of the α-tocopherol isoform of vitamin E with regards to animal and clinical studies. These seemingly disparate results are consistent with our recent studies demonstrating that purified natural forms of vitamin E have opposing regulatory functions during inflammation. In this review, we discuss that α-tocopherol inhibits whereas γ-tocopherol elevates allergic inflammation, airway hyperresponsiveness, leukocyte transendothelial migration, and endothelial cell adhesion molecule signaling through protein kinase Cα. Moreover, we have demonstrated that α-tocopherol is an antagonist and γ-tocopherol is an agonist of PKCα through direct binding to a regulatory domain of PKCα. In summary, we have determined mechanisms for opposing regulatory functions of α-tocopherol and γ-tocopherol on inflammation. Information from our studies will have significant impact on the design of clinical studies and on vitamin E consumption.

Vascular cell adhesion molecule-1 expression and signaling during disease: regulation by reactive oxygen species and antioxidants

The endothelium is immunoregulatory in that inhibiting the function of vascular adhesion molecules blocks leukocyte recruitment and thus tissue inflammation. The function of endothelial cells during leukocyte recruitment is regulated by reactive oxygen species (ROS) and antioxidants. In inflammatory sites and lymph nodes, the endothelium is stimulated to express adhesion molecules that mediate leukocyte binding. Upon leukocyte binding, these adhesion molecules activate endothelial cell signal transduction that then alters endothelial cell shape for the opening of passageways through which leukocytes can migrate. If the stimulation of this opening is blocked, inflammation is blocked. In this review, we focus on the endothelial cell adhesion molecule, vascular cell adhesion molecule-1 (VCAM-1). Expression of VCAM-1 is induced on endothelial cells during inflammatory diseases by several mediators, including ROS. Then, VCAM-1 on the endothelium functions as both a scaffold for leukocyte migration and a trigger of endothelial signaling through NADPH oxidase-generated ROS. These ROS induce signals for the opening of intercellular passageways through which leukocytes migrate. In several inflammatory diseases, inflammation is blocked by inhibition of leukocyte binding to VCAM-1 or by inhibition of VCAM-1 signal transduction. VCAM-1 signal transduction and VCAM-1-dependent inflammation are blocked by antioxidants. Thus, VCAM-1 signaling is a target for intervention by pharmacological agents and by antioxidants during inflammatory diseases. This review discusses ROS and antioxidant functions during activation of VCAM-1 expression and VCAM-1 signaling in inflammatory diseases.

Nutrient-enhanced diet reduces noise-induced damage to the inner ear and hearing loss

Oxidative stress has been implicated broadly as a cause of cell death and neural degeneration in multiple disease conditions; however, the evidence for successful intervention with dietary antioxidant manipulations has been mixed. In this study, we investigated the potential for protection of cells in the inner ear using a dietary supplement with multiple antioxidant components, which were selected for their potential interactive effectiveness. Protection against permanent threshold shift (PTS) was observed in CBA/J mice maintained on a diet supplemented with a combination of β-carotene, vitamins C and E, and magnesium when compared with PTS in control mice maintained on a nutritionally complete control diet. Although hair cell survival was not enhanced, noise-induced loss of type II fibrocytes in the lateral wall was significantly reduced (P < 0.05), and there was a trend toward less noise-induced loss in strial cell density in animals maintained on the supplemented diet. Taken together, our data suggest that prenoise oral treatment with the high-nutrient diet can protect cells in the inner ear and reduce PTS in mice. The demonstration of functional and morphologic preservation of cells in the inner ear with oral administration of this antioxidant supplemented diet supports the possibility of translation to human patients and suggests an opportunity to evaluate antioxidant protection in mouse models of oxidative stress-related disease and pathology.

Isoforms of vitamin E differentially regulate inflammation

Vitamin E regulation of disease has been extensively studied in humans, animal models and cell systems. Most of these studies focus on the α-tocopherol isoform of vitamin E. These reports indicate contradictory outcomes for anti-inflammatory functions of the α-tocopherol isoform of vitamin E, especially with regards to clinical studies of asthma and atherosclerosis. These seemingly disparate clinical results are consistent with recently reported unrecognized properties of isoforms of vitamin E. Recently, it has been reported that physiological levels of purified natural forms of vitamin E have opposing regulatory functions during inflammation. These opposing regulatory functions by physiological levels of vitamin E isoforms impact interpretations of previous studies on vitamin E. Moreover, additional recent studies also indicate that the effects of vitamin E isoforms on inflammation are only partially reversible using physiological levels of a vitamin E isoform with opposing immunoregulatory function. Thus, this further influences interpretations of previous studies with vitamin E in which there was inflammation and substantial vitamin E isoforms present before the initiation of the study. In summary, this review will discuss regulation of inflammation by vitamin E, including alternative interpretations of previous studies in the literature with regards to vitamin E isoforms.

Supplemental and highly elevated tocopherol doses differentially regulate allergic inflammation: reversibility of α-tocopherol and γ-tocopherol's effects

We have reported that supplemental doses of the α- and γ-tocopherol isoforms of vitamin E decrease and increase, respectively, allergic lung inflammation. We have now assessed whether these effects of tocopherols are reversible. For these studies, mice were treated with Ag and supplemental tocopherols in a first phase of treatment followed by a 4-wk clearance phase, and then the mice received a second phase of Ag and tocopherol treatments. The proinflammatory effects of supplemental levels of γ-tocopherol in phase 1 were only partially reversed by supplemental α-tocopherol in phase 2, but were completely reversed by raising α-tocopherol levels 10-fold in phase 2. When γ-tocopherol levels were increased 10-fold (highly elevated tocopherol) so that the lung tissue γ-tocopherol levels were equal to the lung tissue levels of supplemental α-tocopherol, γ-tocopherol reduced leukocyte numbers in the lung lavage fluid. In contrast to the lung lavage fluid, highly elevated levels of γ-tocopherol increased inflammation in the lung tissue. These regulatory effects of highly elevated tocopherols on tissue inflammation and lung lavage fluid were reversible in a second phase of Ag challenge without tocopherols. In summary, the proinflammatory effects of supplemental γ-tocopherol on lung inflammation were partially reversed by supplemental levels of α-tocopherol but were completely reversed by highly elevated levels of α-tocopherol. Also, highly elevated levels of γ-tocopherol were inhibitory and reversible in lung lavage but, importantly, were proinflammatory in lung tissue sections. These results have implications for future studies with tocopherols and provide a new context in which to review vitamin E studies in the literature.

Isoforms of vitamin E have opposing immunoregulatory functions during inflammation by regulating leukocyte recruitment

Reports indicate contradictory outcomes for anti-inflammatory functions of the alpha-tocopherol isoform of vitamin E in clinical studies of asthma and atherosclerosis. These seemingly disparate clinical results are consistent with novel unrecognized properties of isoforms of vitamin E reported in this study. We demonstrate that the isoform d-gamma-tocopherol elevates inflammation in experimental asthma. Moreover, d-gamma-tocopherol, at as little as 10% the concentration of d-alpha-tocopherol, ablates the anti-inflammatory benefit of the d-alpha-tocopherol isoform. A mechanism for these opposing immunoregulatory functions of purified tocopherols at physiological concentrations is not through modulation of expression of several cytokines, chemokines, or adhesion molecules, but is, at least in part, by regulation of endothelial cell signals during leukocyte recruitment. These opposing regulatory functions of vitamin E isoforms have impact on interpretations of vitamin E studies. In summary, our studies with purified tocopherol isoforms alter our understanding of vitamin E regulation of vascular function and asthma.

Age and Vitamin E-Induced Changes in Gene Expression Profiles of T Cells

T cells are vulnerable to age-associated changes. Vitamin E has been shown to improve T cell functions in the old. We studied gene expression profiles of T cells to better understand the underlying mechanisms of age and vitamin E-induced changes in T cell function. Young and old C57BL mice were fed diets containing 30 (control) or 500 (supplemented) ppm of vitamin E for 4 wks. Gene expression profiles of T cells were assessed using microarray analysis with/without anti-CD3/anti-CD28 stimulation. Genes associated with cytokines/chemokines, transcriptional regulation, signal transduction, cell cycle, and apoptosis were significantly up-regulated upon stimulation. Higher SOCS3 and lower growth factor independent 1 (Gfi-1) expression in old T cells may contribute to age-associated decline in proliferation. Higher Gadd45 and lower Bcl2 expression may contribute to increased apoptosis in old T cells. Vitamin E supplementation resulted in higher expression of genes involved in cell cycle regulation (Ccnb2, Cdc2, Cdc6) in old T cells. Vitamin E supplementation resulted in higher up-regulation of IL-2 expression in young and old T cells and lower up-regulation of IL-4 expression in old T cells following stimulation. These findings suggest that aging has significant effects on the expression of genes associated with signal transduction, transcriptional regulation, and apoptosis pathways in T cells, and vitamin E has a significant impact on the expression of genes associated with cell cycle and Th1/Th2 balance in old T cells. Further studies are needed to determine whether these changes are due to the effects of aging at a single-cell level or to the shift in the ratio of naïve:memory T cells with age.

Effect of Concomitant Consumption of Fish Oil and Vitamin E on T Cell Mediated Function in the Elderly: A Randomized Double-Blind Trial

OBJECTIVES

To determine if concomitant consumption of fish oil and vitamin E would modify the vitamin E level needed for improving T cell mediated function in elderly.

METHODS

A randomized and double-blind study was conducted using 40 healthy male and female elderly subjects (>65 y) who were randomly assigned to one of 4 groups (n = 10/group). All the subjects received 5 g of fish oil daily containing 1.5 g eicosapentaenoic acid (EPA) and 1 g docosahexaenoic acid (DHA), and a capsule containing different doses of dl-alpha-tocopherol (0, 100, 200 or 400 mg/day) for 3 mo. Plasma vitamin E and fatty acid levels, and in vivo [delayed-type hypersensitivity skin response (DTH) and T cell sub-population analysis] and ex vivo [mitogen-stimulated peripheral blood mononuclear cells (PBMC) proliferation and interleukin (IL)-2 production] immune functions were determined at baseline and after supplementation.

RESULTS

The control group (fish oil only) did not show a statistically significant change in either DTH or PBMC proliferation. DTH response, however, was significantly increased from baseline in all groups supplemented with fish oil plus vitamin E and a significant positive correlation between DTH response and plasma concentrations of alpha-tocopherol was observed. PBMC proliferation was only significantly increased in the group supplemented with fish oil plus 200 mg vitamin E. However, the changes caused by fish oil plus vitamin E in either DTH or PBMC proliferation were not significantly different from those observed in control group. Plasma levels of alpha-tocopherol were significantly increased in all three fish oil plus vitamin E groups and the increase in plasma alpha-tocopherol level was less profound than that previously reported when vitamin E was given alone.

CONCLUSIONS

The immuno-enhancing effect of vitamin E in the elderly is dampened when it is concomitantly consumed with fish oil. This may be due to the smaller increase in plasma concentrations of vitamin E in the presence of fish oil.

Composition, structure and absorption of milk lipids: a source of energy, fat-soluble nutrients and bioactive molecules

Milkfat is a remarkable source of energy, fat-soluble nutrients and bioactive lipids for mammals. The composition and content of lipids in milkfat vary widely among mammalian species. Milkfat is not only a source of bioactive lipid components, it also serves as an important delivery medium for nutrients, including the fat-soluble vitamins. Bioactive lipids in milk include triacylglycerides, diacylglycerides, saturated and polyunsaturated fatty acids, and phospholipids. Beneficial activities of milk lipids include anticancer, antimicrobial, anti-inflammatory, and immunosuppression properties. The major mammalian milk that is consumed by humans as a food commodity is that from bovine whose milkfat composition is distinct due to their diet and the presence of a rumen. As a result of these factors bovine milkfat is lower in polyunsaturated fatty acids and higher in saturated fatty acids than human milk, and the consequences of these differences are still being researched. The physical properties of bovine milkfat that result from its composition including its plasticity, make it a highly desirable commodity (butter) and food ingredient. Among the 12 major milk fatty acids, only three (lauric, myristic, and palmitic) have been associated with raising total cholesterol levels in plasma, but their individual effects are variable-both towards raising low-density lipoproteins and raising the level of beneficial high-density lipoproteins. The cholesterol-modifying response of individuals to consuming saturated fats is also variable, and therefore the composition, functions and biological properties of milkfat will need to be re-evaluated as the food marketplace moves increasingly towards more personalized diets.

Vitamin E supplementation does not mitigate the acute morbidity effects of porcine reproductive and respiratory syndrome virus in nursery pigs1

The objective of this study was to determine whether feeding a vitamin E-rich diet would benefit nursery pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). Sixty-four pigs were subjected to one of four treatment combinations (2 x 2 factorial) of dietary vitamin E (adequate or excess) and PRRSV (medium or inoculation with VR-2385 isolate P-129). Pigs were fed experimental diets during a 3-wk period before inoculation as well as during a 12-d period after inoculation. Growth performance was determined throughout the study, and lipid peroxidation in liver, glutathione peroxidase (GPX) activity in serum, circulating white blood cells, and serum interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) were determined in samples collected from pigs killed 4 or 12 d after inoculation. Infection by PRRSV (P < 0.001) induced a marked decrease in both ADFI and ADG, but neither the main effect of diet nor the diet x PRRSV interaction was significant. Neither diet nor PRRSV affected feed efficiency. At 12 d after inoculation, lipid peroxidation in liver and GPX activity in serum were lower in pigs fed excess vitamin E than in those fed adequate vitamin E (P < 0.01), suggesting that the diet high in vitamin E bolstered the antioxidant status of the pigs. However, PRRSV did not affect lipid peroxidation in liver or serum GPX activity, and the diet x PRRSV interaction was not significant. White blood cell counts were decreased and IFN-gamma, and IL-1beta were increased (P < 0.05) 4 and 12 d after inoculation in PRRSV-infected pigs, but neither diet nor the diet x PRRSV interaction was significant. Collectively, these results indicate that increasing antioxidant defenses by feeding high levels of vitamin E did not ameliorate the effects of PRRSV on decreased growth, leukopenia, and increased serum IL-1beta and IFN-gamma. Thus, feeding nursery pigs a diet high in vitamin E may not be useful for mitigating the acute morbidity effects of PRRSV infection.

Effect of a high-linolenic acid diet on lipogenic enzyme activities, fatty acid composition, and meat quality in the growing pig

Forty-eight Duroc-cross gilts (40 kg initial BW) were fed a control or a linseed diet containing 60 g of whole crushed linseed/kg. Both diets were supplemented with 150 mg of vitamin E/kg. Eight pigs from each dietary treatment were slaughtered at 20, 60, or 100 d after the start of the experiment. There was no effect (P > 0.05) of diet on growth, carcass characteristics, or foreloin tissue composition. Feeding the linseed diet increased (P < 0.05) the content of n-3 PUFA in plasma, muscle, and adipose tissue, but docosahexaenoic acid was not (P > 0.05) altered by diet. The proportions of n-3 PUFA were highest (P < 0.01) in pigs fed the linseed-diet for 60 d, regardless of tissue (plasma, muscle, or adipose tissue) or lipid (neutral lipids and phospholipids) class. The linseed diet produced a PUFA:saturated fatty acid ratio > or = 0.4 in all groups and tissues, which is close to the recommended value for the entire diet of humans, as well as a robust decrease in the n-6:n-3 ratio. The decrease (P < 0.01) in the percentage of oleic acid in adipose tissue of pigs fed the linseed diet for 60 d could be attributed to a 40% decrease (P < 0.001) in stearoyl-CoA-desaturase activity. Diet did not (P > 0.05) affect the activities of acetyl-CoA-carboxylase, malic enzyme, or glucose-6-phosphate-dehydrogenase in any tissues. Muscle vitamin E content was decreased (P < 0.001) 30% in pigs fed crushed linseed for 60 d, whereas lower (P < 0.001) concentrations of skatole in pork fat were observed in linseed-fed pigs at all slaughter times. Inclusion of linseed (flaxseed) in swine diets is a valid method of improving the nutritional value of pork without deleteriously affecting organoleptic characteristics, oxidation, or color stability.

Suppression of fatty acid synthase by dietary polyunsaturated fatty acids is mediated by fat itself, not by peroxidative mechanism

This study examined the effect of dietary polyunsaturated fatty acids (PUFA) that were supplemented with vitamin E on lipid peroxidation, glutathione-dependent detoxifying enzyme system activity, and lipogenic fatty acid synthase (FAS) expression in rat liver. Male Sprague-Dawley rats were fed semipurified diets containing either 1% (w/w) corn oil or 10% each of beef tallow, corn oil, perilla oil, and fish oil for 4 wk. Alpha-tocopherol was supplemented in perilla oil (0.015%) and fish oil (0.019%). Hepatic thiobarbituric acid reactive substances, an estimate of lipid peroxidation, were not significantly different among the dietary groups. The glutathione peroxidase, glutathione reductase, and glutathione S-transferase activities were all elevated by the polyunsaturated fats, especially fish oil. The activity of FAS was reduced in the polyunsaturated fat-fed groups in the order of fish oil, perilla oil, and corn oil. The mRNA contents decreased in rats that were fed the 10% fat diets, particularly polyunsaturated fats, compared with the rats that were fed the 1% corn oil diet. Similarly, the inhibitory effect was the greatest in fish oil. These results suggest that lipid peroxidation can be minimized by vitamin E; PUFA in itself has a suppressive effect on lipogenic enzyme.

Effects of dietary omega3 and omega6 lipids and vitamin E on chemokine levels in autoimmune-prone MRL/MpJ-lpr/lpr mice

Elevated levels of chemokines, such as Regulated upon Activation, Normal T cell Expressed and Secreted (RANTES), Monocyte Chemotactic Protein-1 (MCP-1), Macrophage Inflammatory Protein-1alpha (MIP-1alpha), and Macrophage Inflammatory Protein-1beta (MIP-1beta) have been found in rheumatoid arthritis (RA) and juvenile arthritis (JA), and they may be associated with the pathogenesis of these diseases. These chemokines are implicated in the migration of specific leukocytes into the joints. Omega-3 (omega3) fatty acid rich-fish oil (FO) and vitamin E may delay the progress of certain autoimmune diseases. The present study was designed to understand the effects of dietary lipids (omega-6 and omega-3 fatty acids) and vitamin E on the production of chemokines in autoimmune-prone MRL/lpr (a mouse model for RA) and congenic control MRL/++ mice. The MRL mice were fed for 4.5 months omega-6 and omega-3 diets that varied in lipid sources (corn oil; CO and fish oil; FO) and vitamin E levels (269 I.U./kg and 694 I.U./kg diet). Spleen cells were isolated and cultured aseptically in the presence of PHA for 48 h at 37 degrees C and the levels of chemokines (RANTES, JE/MCP-1 and MIP-1alpha) were determined in the cell-free supernatants. The levels of RANTES and JE/MCP-1 were significantly higher in MRL/lpr mice compared to MRL/++ mice. The FO had differential effect on RANTES and MCP-1 production by spleen cells. The production of RANTES and JE/MCP-1 by spleen cells in mice fed the FO diets was significantly lower than in mice fed the CO diets (p < 0.0001). The levels of vitamin E did not affect the production of RANTES and JE/MCP-1. The levels of vitamin E had a significant effect on MIP-1alpha as the spleen cells of mice fed diets containing 694 IU/kg diet of vitamin E produced significantly higher levels of MIP-1alpha compared to the group of mice fed the diets containing 269 IU of vitamin E (p < 0.0001). The data obtained from this study in MRL/lpr and MRL/++ mice suggest that FO diets containing omega-3 fatty acids are beneficial in decreasing the levels of certain pro-inflammatory chemokines (RANTES and MCP-1) thereby delaying the onset of and severity of autoimmune symptoms in MRL/lpr mouse model.

Influence of dietary long-chain n-3 fatty acids from Menhaden fish oil on plasma concentrations of -tocopherol in geriatric Beagles

OBJECTIVE

To determine effects of dietary n-3 fatty acids from Menhaden fish oil on plasma alpha-tocopherol concentrations in Beagles.

ANIMALS

32 female Beagles.

PROCEDURE

For 82 days, dogs were fed diets that contained 1 of 2 ratios of n-6:n-3 fatty acids (40:1 [low n-3] and 1.4:1 [high n-3]) and 1 of 3 concentrations of all-rac-alpha-tocopheryl acetate (low, 17 mg/kg of diet; medium, 101 mg/kg; and high, 447 mg/kg) in a 2 X 3 factorial study.

RESULTS

Diets high in n-3 fatty acids significantly increased total content of n-3 fatty acids in plasma (17.0 g/100 g of fatty acids), compared with low n-3 diets (2.02 g/100 g of fatty acids). Mean +/- SEM plasma concentration of cholesterol was significantly lower in dogs consuming high n-3 diets (4.59 +/- 0.48 mmol/L), compared with dogs consuming low n-3 diets (5.71 +/- 0.48 mmol/L). A significant interaction existed between the ratio for n-6 and n-3 fatty acids and amount of alpha-tocopheryl acetate in the diet (plasma alpha-tocopherol concentration expressed on a molar basis), because the plasma concentration of alpha-toco-pherol was higher in dogs consuming low n-3 diets, compared with those consuming high n-3 diets, at the 2 higher amounts of dietary alpha-tocopheryl acetate. Plasma alpha-tocopherol concentration expressed relative to total lipid content did not reveal effects of dietary n-3 fatty acids on concentration of alpha-tocopherol.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma alpha-tocopherol concentration is not dependent on dietary ratio of n-6 and n-3 fatty acids when alpha-tocopherol concentration is expressed relative to the total lipid content of plasma.

Phospholipid hydroperoxide glutathione peroxidase activity and vitamin E level in the liver microsomal membrane: effects of age and dietary alpha-linolenic acid deficiency

Age and diet-induced variations of phospholipid hydroperoxide glutathione peroxidase (PHGPx) activity and alpha-tocopherol concentration in the liver microsomal membrane were studied in male Wistar rats fed a semipurified diet either balanced in n-6 and n-3 polyunsaturated fatty acids (PUFA) (Control) or deprived of alpha-linolenic acid, i.e. n-3 PUFA (Deficient) over two generations. The animals were studied at the age of 6 months (adult) or 24 months (old). Both PHGPx activity and vitamin E level were significantly higher in 24-month old rats as compared to 6-month old rats. By contrast, the thiobarbituric acid reactive substances (TBARS) following stimulated in vitro peroxidation of membrane lipids were markedly lower (P < 0.01) with aging. The fatty acid composition of microsomal membrane phospholipids (PL) was also considerably modified by age. In particular, the levels of arachidonic acid and total n-6 PUFA were lower (P < 0.001) whereas n-3 PUFA levels were higher (P < 0.001) in most PL main classes. The alpha-linolenic acid deficiency markedly influenced these age-related changes. The higher PHGPx activity in the old rats as compared to the adult rats was only significant in those fed the control diet. In the 6-month old rats (but not in the 24-month old rats), the deficient diet led to a higher membrane vitamin E level and to lower TBARS production than the control diet. The results suggest that the nature of dietary PUFA may influence the age-related variations in this pair of membrane antioxidants and also in the fatty acid composition of microsomes.

Effect of long-term dietary antioxidant supplementation on influenza virus infection

This study compared the effect of vitamin E on the course of influenza infection with that of other antioxidants. (In a previous study we showed that short-term vitamin E supplementation significantly decreased pulmonary viral titer in influenza-infected old mice). Eighteen-month-old C57BL/6NCrlBR mice were fed one of the following semisynthetic diets for 6 months: control, vitamin E supplemented, glutathione supplemented, vitamin E and glutathione supplemented, melatonin supplemented, or strawberry extract supplemented. After influenza virus challenge, mice fed vitamin E-supplemented diet had significantly lower pulmonary viral titers compared to those fed the control diet (10(2.6) vs 10(4.0), p < .05) and were able to maintain their body weight after infection (1.8+/-0.9 g weight loss/5 days postinfection in vitamin E group vs 6.8+/-1.4 g weight loss/5 days postinfection in control group, p < .05). Other antioxidants did not have a significant effect on viral titer or weight loss. There was a significant inverse correlation of weight loss with food intake (r = -.96, p < .01), indicating that the observed weight changes were mainly due to decreased food intake. Pulmonary interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha levels increased significantly postinfection. The vitamin E group had lower lung IL-6 and TNF-alpha levels following infection compared to the control group. In addition, there was a significant positive correlation between weight loss and lung IL-6 (r = .77, p < .01) and TNF-alpha (r = .68, p < .01) levels. Because IL-6 and TNF-alpha have been shown to contribute to the anorexic effect of infectious agents, the prevention of weight loss by vitamin E might be due to its reduced production of IL-6 and TNF-alpha following infection. Thus, among the antioxidants tested, only vitamin E was effective in reducing pulmonary viral titers and preventing an influenza-mediated decrease in food intake and weight loss. Other dietary antioxidant supplementations that reduced one or more measures of oxidative stress (4-hydroxynonenal, malondialdehyde, and hydrogen peroxide) did not have an effect on viral titer, which suggests that, in addition to its antioxidant activity, other mechanisms might be involved in vitamin E's beneficial effect on lowering viral titer and preventing weight loss.

Fish oil diet affects on oxidative senescence of red blood cells linked to degeneration of spleen cells in mice

The effect of dietary polyunsaturated fatty acids and alpha-tocopherol supplementation on erythrocyte lipid peroxidation and immunocompetent cells in mice was studied comparatively using seven dietary oils (15% oil/diet, w/w) including fish oil rich in eicosapentaenoic acid (EPA, 20:5, n-3) and docosahexaenoic acid (DHA, 22:6, n-3). A 43% increase in spleen weight, about twice as many spleen cells and no change in the subpopulations of spleen cells, as well as a significant depression of mitogen-induced blastogenesis of both T and B cells in the spleen were observed in mice fed fish oil for 30 days in comparison with soybean oil diet-fed mice. In the fish oil diet-fed mice, membranous lipid hydroperoxide (hydroperoxides of phosphatidylcholine and phosphatidylethanolamine) accumulation as a marker of oxidative senescence in red blood cells (RBC) was 2.7-3.5 times higher than that in mice fed soybean oil, although there was no difference in the plasma phosphatidylcholine hydroperoxide concentration. In spite of the supplementation of alpha-tocopherol to up to 10 times the level in the basal diet, the degeneration of spleen cells and the stimulated oxidative senescence of RBC found by the fish oil feeding could not be prevented. The results suggest that oral intake of excess polyunsaturated fatty acids, i.e. EPA and DHA, in a fish oil diet can lead to acceleration of membrane lipid peroxidation resulting in RBC senescence linked to the lowering of immune response of spleen cells, and that supplementation of alpha-tocopherol as antioxidant does not always effectively prevent such oxidative degeneration as observed in spleen cells and RBC in vivo.

Effect of n-3 polyunsaturated fatty acid supplementation on lipid peroxidation of rat organs

The present study was undertaken in order to reexamine the effect of n-3 polyunsaturated fatty acid (PUFA)-rich diet supplementation on lipid peroxidation and vitamin E status of rat organs. Male Wistar rats were fed a diet containing safflower or fish oil at 50 g/kg diet and an equal amount of vitamin E at 59 mg/kg diet (1.18 g/kg oil; and 1.5 g/kg PUFA in safflower oil diet, and 4.3 g/kg PUFA in fish oil diet) for 6 wk. Fatty acid composition of total lipids of brain, liver, heart, and lung of rats fed fish oil was rich in n-3 PUFA, whereas that of each organ of rats fed safflower oil was rich in n-6 PUFA. The vitamin E levels in liver, stomach, and testis of the fish oil diet group were slightly lower than those of the safflower oil diet group, but the levels in brain, heart, lung, kidney, and spleen were not different between the two diet groups. The levels of phospholipid hydroperoxides were determined by the high-performance liquid chromatography-chemiluminescence method and the levels of thiobarbituric acid-reactive substances (TBARS) were determined at pH 3.5 in the presence of butylated hydroxytoluene with or without EDTA. Levels of phospholipid hydroperoxides and TBARS in the brain, liver, heart, lung, kidney, spleen, stomach and testis of the fish oil diet group were similar to those of the safflower oil diet group. The results indicate that high fish oil intake does not induce increased levels of phospholipid hydroperoxides and TBARS in rat organs.

Encapsulated fish oil enriched in alpha-tocopherol alters plasma phospholipid and mononuclear cell fatty acid compositions but not mononuclear cell functions

BACKGROUND

Several studies have reported that dietary fish oil (FO) supplementation alters cytokine production and other functional activities of peripheral blood mononuclear cells (PBMC). However, few of these studies have been placebo controlled and few have related the functional changes to alterations in PBMC fatty acid composition

PATIENTS AND METHODS

Healthy subjects supplemented their diets with 9 g day-1 of encapsulated placebo oil (3 : 1 mix of coconut and soybean oils), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or FO [providing 2.1 g eicosapentaenoic acid (EPA) plus 1.1 g docosahexaenoic acid (DHA) per day] for 12 weeks; the capsules also provided 205 mg alpha-tocopherol per day. Blood was sampled at 4-weekly intervals and plasma and PBMC prepared. Plasma phospholipid and PBMC fatty acid composition, plasma alpha-tocopherol and thiobarbituric acid-reactive substance concentrations, plasma total antioxidant capacity, the proportions of different PBMC subsets, the proportions of PBMC expressing the adhesion molecules CD2, CD11b and CD54, and PBMC functions (lymphocyte proliferation, natural killer cell activity, cytokine production) were measured. All measurements were repeated after a 'washout' period of 8 weeks.

RESULTS

The placebo, OO and SO capsules had no effect on plasma phospholipid or PBMC fatty acid composition. The proportion of dihomo-gamma-linolenic acid in plasma phospholipids was elevated in subjects taking EPO and was decreased in subjects taking FO. There was no appearance of gamma-linolenic acid in the plasma phospholipids or PBMC in subjects taking EPO. There was a marked increase in the proportion of EPA in the plasma phospholipids (10-fold) and PBMC (four-fold) of subjects taking FO supplements; this increase was maximal after 4 weeks of supplementation. There was an increase in the proportion of DHA in plasma phospholipids and PBMC, and an approximately 20% decrease in the proportion of arachidonic acid in plasma phospholipids and PBMC, during FO supplementation. Plasma concentrations of alpha-tocopherol were significantly elevated during supplementation in all subjects and returned to baseline values after the washout period. There were no effects of supplementation with any of the capsules on total plasma antioxidant activity or plasma thiobarbituric acid-reactive substances or on the proportion of different PBMC subsets, on the proportion of PBMC expressing adhesion molecules, on natural killer cell activity, on the proliferation of mitogen-stimulated whole blood cultures or PBMC, or on the ex vivo production of a range of cytokines by whole blood cultures or PBMC cultures stimulated by either concanavalin A or lipopolysaccharide.

CONCLUSION

Supplementation of the diet with 3.2 g EPA plus DHA per day markedly alters plasma phospholipid and PBMC fatty acid compositions. The lack of effect of FO upon PBMC functions may relate to the level of alpha-tocopherol included in the supplements.

Omega-3 fatty acids alter soluble markers of endothelial function in coronary heart disease patients

Several studies have indicated that omega-3 poly-unsaturated fatty acids in fish oil have protective effects on cardiovascular disease by reducing vascular endothelial inflammation in atherosclerosis. In a recent study, supplementation of patients with fish oil following coronary angioplasty elevated levels of lipid peroxides and two adhesion molecules in plasma suggesting a proinflammatory action of fish oil. However, decreases in several plasma markers of endothelial hemostatic activity indicated a healthier and better vasculature associated with fish oil supplementation.

Modulation of lipid peroxidation and antioxidant enzymes in murine salivary gland by dietary fatty acid ethyl esters

The present study was undertaken to investigate the effect of n-9, n-6, and n-3 dietary fatty acid ethyl esters on basal (uninduced) and Fe2+/ascorbate (induced) lipid peroxidation (LPO) in salivary gland (SG) of mice. Feeding n-3 ethyl ester polyunsaturated fatty acids (PUFA) increased the uninduced and induced LPO in SG homogenates. In contrast, feeding olive oil ethyl esters (n-9) significantly lowered the induced and uninduced LPO in SG tissue. Salivary gland susceptibility to LPO increased in the order of: olive oil < corn oil < safflower oil < n-3 ethyl esters. Olive oil esters in the diet increased primarily the 18:1 levels in SG tissue. Whereas feeding n-3 PUFA notably increased the superoxide dismutase (SOD) and catalase activities in SG homogenates, no significant changes were seen between n-9 and n-6 PUFA-fed mice. Lower levels of Vitamin E (Vit E) in the tissues of n-3 PUFA-fed mice indicate that the higher the dietary lipid unsaturation, the higher the requirement for Vit E in the diet. Our results indicate that, similar to other organs, salivary gland susceptibility to uninduced or induced oxidation depends on the source of dietary PUFA. In conclusion, feeding olive oil increases the resistance of SGs to induced and uninduced LPO.

The effects of dietary antioxidants on psychomotor performance in aged mice

Male C57BL/6NIA mice were provided one of six different antioxidant diets: vitamin E, glutathione, vitamin E plus glutathione, melatonin, strawberry extract, or control, beginning at 18 months of age. A battery of motor tests--rod walk, wire hang, plank walk, and inclined screen-was administered either: 1) before dietary treatment and then 6 months later at 24 months of age: or 2) only after 6 months of dietary treatment at age 24 months. An untreated group of 4-month-old mice served as young controls. Psychomotor performance was lower in 18-month-old mice compared with 4-month-old mice in the rod walk, wire hang, and inclined screen tests; however, no further decline was seen from 18 to 24 months on any measure. Chronic dietary antioxidant treatments were not effective in reversing age-related deficits in psychomotor behavior, except for the glutathione diet on inclined screen performance. It seems that motor performance deteriorates profoundly with age, because deficits at 18 months of age were as severe as they were at 24 months, and these age-associated motor deficits may be difficult to reverse, even with antioxidant treatment.

Effect of dietary fish oil, vitamin E, and probucol on renal injury in the rat

Dietary fish oil, vitamin E, and probucol have been considered in a variety of human and experimental models of kidney disease. Using subtotal nephrectomized cholesterol-fed rats as a model for progressive kidney disease, we examined the effect of 5% dietary fish oil, or a combination of 5% dietary fish oil with 500 IU vitamin E/kg diet or 1% probucol on renal injury. Three-month-old Sprague Dawley rats were fed a control diet (C group) or a cholesterol supplemented (2%) diet (Ch group) containing either fish oil (FO group) or fish oil plus vitamin E (FO+E group) or fish oil plus probucol (FO+P group). After 4 weeks of dietary treatment, the right kidney was electrocoagulated and the left kidney nephrectomized. After 8 weeks, 24-hour urine was collected before sacrifice. No effect of the dietary treatments was noted on serum creatinine, blood urea nitrogen, or proteinuria, except that proteinuria was highest in FO+P group. Rats receiving the cholesterol diets had higher serum low density lipoprotein (LDL) + very low density lipoprotein (VLDL) cholesterol (P < 0.05). In contrast, rats in the FO+P group had the lowest serum total cholesterol and LDL+VLDL cholesterol among all groups. The FO group had 26% lower kidney alpha-tocopherol concentrations than the C group. However, inclusion of vitamin E in the diet (FO+E group) increased the kidney alpha-tocopherol status to a level comparable to that in the C group, whereas inclusion of probucol in fish oil diet (FO+P group) did not improve the kidney alpha-tocopherol status. Rats fed the cholesterol diet had a 2.5-fold higher glomerular segmental sclerosis (GSS) score and 1.5-fold higher glomerular macrophage (GM) subpopulation than the C group. These effects of the cholesterol diet were ameliorated by a fish oil diet (FO group: GSS by 30%, GM by 24%). The inclusion of vitamin E in the fish oil diet (FO+E group) did not further improve the GSS score or GM subpopulation. However, inclusion of probucol in fish oil diet (FO+P group) lowered the GSS score by 73% and reduced GM subpopulation by 83% compared with the Ch group. These remarkable changes can be attributed to the powerful hypocholesterolemic activity of probucol. Our findings indicate that progression of glomerular sclerosis in the rat remnant kidney model of progressive kidney disease can be significantly modulated with fish oil treatment.

Effect of oxidized fish oil and alpha-tocopherol on the peroxidation of erythrocyte membrane phospholipids in rats

The effects of dietary oxidized fish oil and alpha-tocopherol on the thiobarbituric acid (TBA) values and phospholipid hydroperoxide levels of the erythrocyte membrane were studied in rats. No significant differences in the TBA values or phospholipid hydroperoxide levels of the membrane were observed between groups fed either oxidized fish oil or control diets. Furthermore, there were no marked differences in these values whether or not the groups were administered diets containing added alpha-tocopherol. These results suggest that the intake of oxidized fish oil and the supplementation with alpha-tocopherol do not influence the level of lipid peroxidation in the erythrocyte membrane.

Determination of alpha-tocopherol and alpha-tocopherol acetate in diets of experimental animals. Study of stability in the diets

A simple method is described which permits, avoiding saponification, alpha-tocopherol and alpha-tocopheryl acetate measurement in semi-synthetic diets for experimental animals by HPLC, with both UV and fluorescence detection. Phenyldodecane was chosen as internal standard with remarkable performances, and EDTA and BHT were added to prevent oxidation in aqueous and non-aqueous phases respectively. The mobile phase was methanol-water (94:6 v/v) at a flow-rate of 2 ml/min. Samples were homogenized and extracted twice with n-hexane by probe sonication. Extracts were evaporated to dryness and redissolved with chloroform-methanol (1:1, v/v). Validation parameters were studied between 25 ng and 6 micrograms for alpha-tocopherol and between 3 and 24.2 micrograms for alpha-tocopheryl acetate, which corresponds to the range of values in the existing diets. Results had correlation coefficients > 0.99; recoveries > 85%; R.S.D. < 6%, so the method is adequate to control vitamin E intake in animals as well as vitamin E stability in food during storage.

n-3 polyunsaturated fatty acids and immune function

n-3 PUFA have been shown to reduce the risk of cardiovascular and inflammatory diseases. However, they have also been shown to suppress T-cell-mediated immune function, an undesirable effect, especially in immuno-suppressed individuals. Studies have thus far suggested that this immuno-suppression may be in part attributable to increased lipid peroxidation and decreased antioxidant (especially vitamin E) levels, which can be prevented by appropriate vitamin E supplementation. Further well-designed human studies are needed to determine the appropriate levels of n-3 PUFA and vitamin E supplementation to optimize the beneficial anti-inflammatory effect of n-3 PUFA and minimize their suppressive effect on T-cell function.

Disease incidence and longevity are unaltered by dietary antioxidant supplementation initiated during middle age in C57BL/6 mice

The ability of augmented antioxidant consumption to alter disease incidence, lesion burden and/or longevity was studied in adult male C57BL/6 mice. Mice were fed modified AIN76 diet or modified AIN76 supplemented with vitamin E, glutathione (GSH), vitamin E and GSH, melatonin or strawberry extract starting at 18 months of age. All the mice in this study were heavier than reference populations of male C57BL/6 mice fed NIH-07 or NIH-31, which were maintained without a mid-life change in diet. Fatty liver, focal kidney atrophy and proteinacious casts in the renal tubules were observed more frequently in this study population than in the reference populations. Lesion burden and incidence of specific lesions observed amongst the various groups in this study did not differ. There were no differences observed for longevity of any of the study groups. The longevity observed in this study was similar to that previously reported for male C57BL/6 mice. Thus, diet supplementation with antioxidants initiated during middle age did not appear to affect age-associated lesions patterns, lesion burden or longevity for ad libitum fed male C57BL/6 mice.

Effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in rat erythrocyte membranes

Human erythrocytes in the circulation undergo dynamic oxidative damage involving membrane lipid peroxidation and protein aggregation during aging. The present study was undertaken to determine the effect of n-3 fatty acid supplementation on lipid peroxidation and protein aggregation in the circulation and also the in vitro susceptibility of rat erythrocyte membranes to oxidative damage. Wistar male rats were fed a diet containing n-6 fatty acid-rich safflower oil or n-3 fatty acid-rich fish oil with an equal amount of vitamin E for 6 wk. n-3 Fatty acid content in erythrocyte membranes of rats fed fish oil was significantly higher than that of rats fed safflower oil. The degree of membrane lipid peroxidation and protein aggregation of rats fed fish oil was not significantly higher than that of rats fed safflower oil when the amounts of phospholipid hydroperoxides, thiobarbituric acid-reactive substances, and detergent-insoluble protein aggregates were measured. When isolated erythrocytes were oxidized under aerobic conditions in the presence of Fe(III), the degree of membrane lipid peroxidation of erythrocytes from rats fed fish oil was increased to a greater extent than that of rats fed safflower oil, whereas the degree of membrane protein aggregation of both groups was increased in a similar extent. Hence, n-3 fatty acid supplementation did not affect lipid peroxidation and protein aggregation in membranes of circulating rat erythrocytes, and the supplementation increased the susceptibility of isolated erythrocytes to lipid peroxidation, but not to protein aggregation, under the aerobic conditions. If a sufficient amount of vitamin E is supplied, n-3 fatty acid supplementation may give no undesirable oxidative effects on rat erythrocytes in the circulation.

Effect of dietary catechin and vitamin E on aortic fatty streak accumulation in hypercholesterolemic hamsters

Male golden Syrian hamsters were fed for 16 weeks on a hypercholesterolemic diet containing, per kg, 150 g of lipids (90 g butterfat, 35 g vitamin E-stripped corn oil and 25 g fish oil), 2 g cholesterol and either 3 IU vitamin E (3 IU E), 3 IU vitamin E and 200 mg catechin hydrate (3 IU E-200 Cat) or 30 IU vitamin E (30 IU E). More fatty streaks, measured by Oil Red O staining, were deposited in aortas of hamsters fed 3 IU E than in those fed either 3 IU E-200 Cat or 30 IU E. Lipid staining increased with plasma low-density lipoprotein cholesterol (LDL-C) in all animals. At the same concentration of LDL-C, animals fed either 3 IU E-200 Cat or 30 IU E developed less fatty streaks than those fed 3 IU E. Plasma LDL-C and total cholesterol were highest in hamsters fed 3 IU E and LDL-C and total cholesterol in animals fed 3 IU-200 Cat were not different from those fed either 3 IU E or 30 IU E. This study showed the importance of circulating plasma LDL-C on atherogenesis and the inhibitory effect on this process of both dietary vitamin E and catechin.

Lipids and the immune response

The effects of fatty acids on immune responses have been studied since the early 1970s, but much controversy still remains. The present review examines recent studies in both animals and in humans, and highlights some new and exciting ideas concerning the mechanism by which fatty acids may affect immune responses in both normal and pathological situations, an area which is likely to progress rapidly over the next few years.

Dietary supplementation with mushroom-derived protein-bound glucan does not enhance immune function in young and old mice

Decline in immune response is a well-documented age-associated biological change. Protein-bound polysaccharides (PSP) are biological response modifiers and have been shown to have immunoenhancing and antitumor effects. This study was conducted to examine the effect of dietary supplementation with PSP-containing extract derived from mycelia of Coriolus versicolor on in vitro and in vivo indices of immune function of young and old mice. Young (5 mo) and old (23 mo) C57BL/6NIA mice were fed purified diets containing 0, 0.1, 0.5 or 1.0% PSP for 1 mo at which time indices of immune function were measured. PSP supplementation had no significant effect on mitogenic response to concanavalin A (Con A), phytohemagglutinin (PHA) or lipopolysaccharide (LPS), or on production of interleukin (IL)-1, IL-2, IL- 4 and prostaglandin E2 (PGE2). Of the in vivo indices of immune function tested, old mice fed 1.0% PSP had significantly higher delayed-type hypersensitivity (DTH) response than those fed 0% PSP. No significant effect of PSP was observed on the DTH response of young mice. The antibody response to sheep red blood cells was not significantly influenced by PSP in young or old mice. These results suggest that PSP-containing extract from mycelia of Coriolus versicolor might have a modest immunoenhancing effect in aged mice, but not in young mice.

Low-dose eicosapentaenoic or docosahexaenoic acid administration modifies fatty acid composition and does not affect susceptibility to oxidative stress in rat erythrocytes and tissues

In view of the promising future for use of n-3 polyunsaturated fatty acids (PUFA) in the prevention of cancer and cardiovascular diseases, it is necessary to ensure that their consumption does not result in detrimental oxidative effects. The aim of the present work was to test a hypothesis that low doses of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) do not induce harmful modifications of oxidative cell metabolism, as modifications of membrane fatty acid composition occur. Wistar rats received by gavage oleic acid, EPA, or DHA (360 mg/kg body weight/day) for a period of 1 or 4 wk. Fatty acid composition and alpha-tocopherol content were determined for plasma, red blood cell (RBC) membranes, and liver, kidney, lung, and heart microsomal membranes. Susceptibility to oxidative stress induced by tert-butylhydroperoxide was measured in RBC. EPA treatment increased EPA and docosapentaenoic acid (DPA) content in plasma and in all the membranes studied. DHA treatment mainly increased DHA content. Both treatments decreased arachidonic acid content and n-6/n-3 PUFA ratio in the membranes, without modifying the Unsaturation Index. No changes in tissue alpha-tocopherol content and in RBC susceptibility to oxidative stress were induced by either EPA or DHA treatment. The data suggest that EPA and DHA treatments can substantially modify membrane fatty acids, without increasing susceptibility to oxidative stress, when administered at low doses. This opens the possibility for use of low doses of n-3 PUFA for chemoprevention without risk of detrimental secondary effects.

Fish oil-supplemented feeding does not attenuate warm liver ischemia and reperfusion injury in the rat

Liver ischemia and reperfusion injury is mediated by oxygen free radicals, cytokines, and prostanoids produced by Kupffer cells and infiltrating neutrophils. Fish oil-supplemented diets alter membrane phospholipid composition and modify prostanoids and cytokine production in response to ischemia and reperfusion. This study tested the hypothesis that a fish oil-supplemented diet would attenuate warm liver ischemia and reperfusion injury in the rat. Male Sprague-Dawley rats were fed Vital HN supplemented with either fish oil (FO) or corn oil (CO) by the continuous duodenal infusion for 5 days. Total dietary fat (26% of total calories), caloric intake (70 cal/day), and volume (60 ml/day) were identical between two groups. Plasma eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels increased significantly in rats fed fish oil (0 to 16.3% for EPA and 2 to 12% for DHA). Liver histology was similar in both groups before ischemia. On Day 6, rats were subjected to 60 min of reversible hepatic ischemia. Plasma TNF levels, 1 and 24 hr after reperfusion, were not different between FO and CO rats. Liver injury assessed by bile flow, histology, plasma ALT, and bile glutathione efflux did not differ between groups. We conclude that our fish oil-supplemented enteral diet does not attenuate warm liver ischemia and reperfusion injury in rats.

Oxidative stress and antioxidant status in mouse liver: effects of dietary lipid, vitamin E and iron

The purpose of this study was to determine the effects of dietary fat, vitamin E and iron on oxidative damage and antioxidant status. Male Swiss-Webster mice (1 mo old) were fed a basal vitamin E-deficient diet that contained either 8% fish oil + 2% corn oil or 10% lard with or without 1 g dl-alpha-tocopheryl acetate. The diets without vitamin E contained either 0.21 or 0.95 g ferric citrate/kg. Diets were fed for 4 wk/kg diet. Compared with the vitamin E-supplemented groups, mice fed diets without vitamin E (with or without supplemental iron) had significantly (P < 0.05) higher hepatic levels of thiobarbituric acid-reactive substances (TBARS), conjugated dienes and protein carbonyls when they were fed fish oil, but not lard. The levels of TBARS were further increased by iron supplementation in the mice fed fish oil. Significantly lower concentrations of alpha-tocopherol and higher glutathione (GSH) were found in the liver of mice fed fish oil and vitamin E than in those fed lard and vitamin E (P < 0.05). The activities of superoxide dismutase and glucose-6-phosphate dehydrogenase were lower in the fish oil-fed mice than in those fed lard (P < 0.05). The activities of Se-GSH peroxidase, non-Se-GSH peroxidase, catalase, and glutathione reductase were not altered by dietary fat or vitamin E/iron. The results obtained provide experimental evidence of the prooxidative effects of high dietary fish oil and iron, and suggest that vitamin E protects not only lipid-soluble compounds, but also water-soluble constituents, against oxidative damage. Further, dietary lipid plays a key role in determining cellular susceptibility to oxidative stress.

Fish oil source differentially affects rat immune cell alpha-tocopherol concentration

We have previously reported that both the source of dietary fish oil and the chemical form of vitamin E supplied in the diet affect the vitamin E status of immune cells in rats. The purpose of this study was to investigate further the effect of fish oil source on immune cell vitamin E status using free alpha-tocopherol (alpha-T) at the AIN recommended level as the sole source of vitamin E. Sixty weanling female rats were fed semipurified, high fat (20 g/100 g) diets containing either tocopherol-stripped lard (LRD), menhaden fish oil (MFO), sardine fish oil (SRD) or cod liver oil (CLO) as the primary lipid source. Endogenous alpha-T concentration was measured and equalized to 150 mg/kg oil by addition of free RRR-alpha-T to each lipid source, allowing for a final concentration of alpha-T in the mixed diet of 30 mg/kg. An additional group of rats was fed LRD without supplemental vitamin E (LRD-) as a negative control. After feeding experimental diets for 5 or 10 wk, tissues were collected for alpha-T analysis by HPLC. After 5 wk, plasma and liver alpha-T (micromol alpha-T/g lipid) were significantly lower in SRD- and CLO-fed rats compared with LRD-fed rats. At 10 wk, only plasma alpha-T in CLO-fed rats remained significantly depressed. Plasma and liver alpha-T concentrations (micromol alpha-T/g lipid) were not significantly lower in MFO-fed rats than LRD-fed rats at either time point. Compared with LRD, feeding MFO to rats for 5 or 10 wk resulted in significantly greater alpha-T content of immune cells. In similar fashion, SRD-fed rats, compared with LRD-fed rats, also had significantly greater alpha-T content in splenocytes at both time points and greater thymocyte alpha-T at 10 wk. In all instances, the alpha-T status of rats fed CLO was indistinguishable from that of rats fed the vitamin E-free diet (LRD-). These data further demonstrate the complexity of the relationship between vitamin E status and dietary (n-3) polyunsaturated fatty acids (PUFA).

A rapid method for the determination of vitamin E forms in tissues and diet by high-performance liquid chromatography using a normal-phase diol column

This paper describes a simple method for the analysis of tocopherols in tissues by which frozen tissues-70 degrees C were pulverized at dry ice temperatures (-70 degrees C) and immediately extracted with hexane. There was no need to remove the coeluting lipids from tissues by saponification, since at that level of neutral lipids in the sample, there was no reduction in fluorescence response. For the analysis of oil, in which large amounts of neutral lipids were coextracted, a 20% reduction of fluorescence response was observed, but the response was equal for all tocopherol forms, and was appropriately corrected. Saponification was used only when tocopherol esters were present, and only after an initial hexane extraction to remove the free tocopherols in order to avoid their loss by saponification, particularly non alpha-tocopherol and tocotrienols. All the tocopherols and tocotrienols were separated on a normal-phase diol (epoxide) column that gave consistent and reproducible results, without the disadvantages of nonreproducibility with silica columns, or the lack of separation with reversed-phase columns. The tocopherols were quantitated by using a tocopherol form not present in the sample as an internal tocopherol standard, or using an external tocopherol standard if all forms were present, or when the sample was saponified. Piglet heart and liver samples showed the presence of mainly alpha-tocopherol, with minor amounts of beta- and gamma-tocopherol and alpha-tocotrienol, but no delta-tocopherol. Only small amounts of tocopherol esters were present in the liver but not in the heart.