In vitro supplementation with different tocopherol homologues can affect the function of immune cells in old mice

Exploring the characteristics, digestion behaviors, and nutraceutical potential of the underutilized Chimonanthus praecox (L.) link kernel oil: A combined in vitro and in vivo study

Chimonanthus praecox (L.) Link kernel oil (LMO) has the potential to expand the variety of nutraceutical plant oils available and provide support for the application of functional food. This study aimed to assess the edible potential of LMO by examining its physicochemical characteristics, digestion behaviors, and nutraceutical properties. The results revealed that LMO has a high oil content of 40.84% and is particularly rich in linoleic acid (53.37-56.30%), oleic acid (22.04-25.08%) and triacylglycerol (TAG) of linoleic acid -palmitoleic acid- oleic acid (10.57-12.70%). The quality characteristics and phytochemical composition of LMO were found to be influenced by variety and extraction methods used. In simulated in vitro digestion tests, LMO showed a better lipid release rate and degree. Animal studies further demonstrated that LMO led to better TAG and cholesterol excretion compared to soybean oil and camellia oleifera oil. Overall, this study highlights the potential of LMO as a high-quality edible oil.

Vaccines, Microbiota and Immunonutrition: Food for Thought

Vaccines are among the most effective health measures and have contributed to eradicating some diseases. Despite being very effective, response rates are low in some individuals. Different factors have been proposed to explain why some people are not as responsive as others, but what appears to be of critical importance is the presence of a healthy functioning immune system. In this respect, a key factor in modulating the immune system, both in its adaptive and innate components, is the microbiota. While microbiota can be modulated in different ways (i.e., antibiotics, probiotics, prebiotics), an effective and somewhat obvious mechanism is via nutrition. The science of nutrients and their therapeutic application is called immunonutrition, and it is increasingly being considered in several conditions. Our review will focus on the importance of nutrition and microbiota modulation in promoting a healthy immune system while also discussing the overall impact on vaccination response.

A review on nutritional composition, antinutritional components and health benefits of green gram (Vigna radiata (L.) Wilczek)

Green gram is rich in proteins, carbohydrate, dietary fiber, vitamins, and minerals and contains a low amount of fat. Since it is rich in protein, it can be considered as the meat alternative for vegetarians. Besides being a nutritious food, green gram possesses potential health benefits such as antioxidant, anticancerous, anti-inflammatory and hypolipidemic activities. Green gram has prebiotic and nutraceutical properties. It contains an appreciable amount of galactooligosaccharides that are capable of enhancing the growth of beneficial gut microbiota. Different researchers already developed functional foods such as mung bean milk and non-diary probiotic drinks from green gram. It can also be used as a carrier material to deliver probiotic bacteria to the gut. Apart from these applications, green gram is used in cosmetics, land reclamation and incorporated into different foods such as jams, jellies, noodles, etc. Green gram is also a major ingredient used in China's traditional health foods. PRACTICAL APPLICATIONS: Green gram is rich in proteins, carbohydrate, dietary fiber, vitamins, and minerals and contains a low amount of fat. Since it is rich in protein, it can be considered as the meat alternative for vegetarians. Besides being a nutritious food, green gram possesses potential health benefits such as antioxidant, anticancerous, antioxidant, anti-inflammatory and hypolipidemic activities. Green gram has prebiotic and nutraceutical properties. It contains an appreciable amount of oligosaccharides that are capable of enhancing the growth of beneficial gut microbiota. Different researchers already developed functional foods such as mung bean milk and non-diary probiotic drinks from green gram. It can also be used as a carrier material to deliver probiotic bacteria to the gut. Apart from these applications, green gram is used in cosmetics and land reclamation and incorporated into different foods such as jams, jellies, noodles, etc. Green gram is also a major ingredient used in China's traditional health foods.

Regulatory role of vitamin E in the immune system and inflammation

Vitamin E, a potent lipid-soluble antioxidant, found in higher concentration in immune cells compared to other cells in blood, is one of the most effective nutrients known to modulate immune function. Vitamin E deficiency has been demonstrated to impair normal functions of the immune system in animals and humans, which can be corrected by vitamin E repletion. Although deficiency is rare, vitamin E supplementation above current dietary recommendations has been shown to enhance the function of the immune system and reduce risk of infection, particularly in older individuals. The mechanisms responsible for the effect of vitamin E on the immune system and inflammation have been explored in cell-based, pre-clinical and clinical intervention studies. Vitamin E modulates T cell function through directly impacting T cell membrane integrity, signal transduction, and cell division, and also indirectly by affecting inflammatory mediators generated from other immune cells. Modulation of immune function by vitamin E has clinical relevance as it affects host susceptibility to infectious diseases such as respiratory infections, in addition to allergic diseases such as asthma. Studies examining the role of vitamin E in the immune system have typically focused on α-tocopherol; however, emerging evidence suggests that other forms of vitamin E, including other tocopherols as well as tocotrienols, may also have potent immunomodulatory functions. Future research should continue to identify and confirm the optimal doses for individuals at different life stage, health condition, nutritional status, and genetic heterogeneity. Future research should also characterize the effects of non-α-alpha-tocopherol vitamin E on immune cell function as well as their potential clinical application. © 2018 IUBMB Life, 71(4):487-494, 2019.

Perspective: Should Vitamin E Recommendations for Older Adults Be Increased?

Current vitamin E requirements are uniformly applied across the population for those >14 y of age. However, aging is associated with alterations in cellular and physiologic functions, which are affected by vitamin E. Therefore, it is questionable whether vitamin E requirements can be uniformly applied to all adult age categories. With aging, there is dysregulation of the immune system in which there are decreased cell-mediated and pathogen defense responses coupled with an overactive, prolonged inflammatory state. Both animal and human studies in the aged suggest that intake above currently recommended levels of vitamin E may improve immune and inflammatory responses and be associated with a reduced risk of infectious disease. We review the evidence that was considered in establishing the current requirements for vitamin E and highlight data that should be considered in determining the vitamin E requirements in older adults, particularly focusing on the evidence suggesting a benefit of increased vitamin E intake on immune function and inflammatory processes and resistance to infection. The main objective of this Perspective is to initiate the discussion of whether the current Dietary Reference Intake for vitamin E should be increased for the older population. We make this suggestion on the basis of mechanistic studies showing biological plausibility, correction of a major cellular dysfunction in older adults, and strong evidence from several animal and a few human studies indicating a reduction in risk and morbidity from infections.

Update on Vitamin E and Its Potential Role in Preventing or Treating Bronchopulmonary Dysplasia

Vitamin E is obtained only through the diet and has a number of important biological activities, including functioning as an antioxidant. Evidence that free radicals may contribute to pathological processes such as bronchopulmonary dysplasia (BPD), a disease of prematurity associated with increased lung injury, inflammation and oxidative stress, led to trials of the antioxidant vitamin E (α-tocopherol) to prevent BPD with variable results. These trials were all conducted at supraphysiologic doses and 2 of these trials utilized a formulation containing a potentially harmful excipient. Since 1991, when the last of these trials was conducted, both neonatal management strategies for minimizing oxygen and ventilator-related lung injury and our understanding of vitamin E isoforms in respiratory health have advanced substantially. It is now known that there are differences between the effects of vitamin E isoforms α-tocopherol and γ-tocopherol on the development of respiratory morbidity and inflammation. What is not known is whether improvements in physiologic concentrations of individual or combinations of vitamin E isoforms during pregnancy or following preterm birth might prevent or reduce BPD development. The answers to these questions require adequately powered studies targeting pregnant women at risk of preterm birth or their premature infants immediately following birth, especially in certain subgroups that are at increased risk of vitamin E deficiency (e.g., smokers). The objective of this review is to compile, update, and interpret what is known about vitamin E isoforms and BPD since these first studies were conducted, and suggest future research directions.

Vitamin E and wound healing: an evidence-based review

Vitamin E has been demonstrated to modulate cellular signalling, gene expression and affect wounds infected with methicillin-resistant Staphylococcus aureus (MRSA), thus influencing wound healing. This evidence-based review aimed to identify and evaluate current research assessing the properties of vitamin E in relation to wound healing, through its role as an antioxidant and its influence on connective tissue growth factor (CTGF), MRSA and gene transcription. Literature dated from 1996 to 2012, published in English, involving either animals or adult humans with an acute or chronic wound were included. The databases that contained relevant articles were narrowed down to four, and a total of 33 identified studies were included. The literature review revealed that there is a significant dearth of robust studies establishing the effects of vitamin E on wound healing, and further research is clearly warranted.

Effects of vitamin e on bone biomechanical and histomorphometric parameters in ovariectomized rats

The present study examined the dose-dependent effect of vitamin E in reversing bone loss in ovariectomized (Ovx) rats. Sprague-Dawley rats were either Sham-operated (Sham) or Ovx and fed control diet for 120 days to lose bone. Subsequently, rats were divided into 5 groups (n = 12/group): Sham, Ovx-control, low dose (Ovx + 300 mg/kg diet; LD), medium dose (Ovx + 525 mg/kg diet; MD), and high dose (Ovx + 750 mg/kg diet; HD) of vitamin E and sacrificed after 100 days. Animals receiving MD and HD of vitamin E had increased serum alkaline phosphatase compared to the Ovx-control group. Bone histomorphometry analysis indicated a decrease in bone resorption as well as increased bone formation and mineralization in the Ovx groups supplemented with MD and HD of vitamin E. Microcomputed tomography findings indicated no effects of vitamin E on trabecular bone of fifth lumbar vertebrae. Animals receiving HD of vitamin E had enhanced fourth lumbar vertebra quality as evidenced by improved ultimate and yield load and stress when compared to Ovx-control group. These findings demonstrate that vitamin E improves bone quality, attenuates bone resorption, and enhances the rate of bone formation while being unable to restore bone density and trabecular bone structure.

Antiproliferative and proapoptotic effects of tocopherol and tocol on activated hepatic stellate cells

Activated hepatic stellate cells (HSCs) play crucial roles in liver fibrosis. In the course of liver injury, HSCs, which reside in perisinusoidal spaces and lose lipid droplets, morphologically change into a myofibroblastic phenotype and acquire an increased proliferation activity in what is known as the activated state. We have investigated therapeutic strategies for liver fibrosis by promoting spontaneous reversion or inducing apoptosis in activated HSCs. Vitamin E consists of four tocopherols and four tocotrienols, all of which are well-known antioxidants. In this study, the antiproliferative and proapoptotic effects of a tocol, which lacks methyl groups attached to the chromanol ring, and four tocopherols were investigated using activated HSCs. δ-Tocopherol and tocol exhibited relatively high proliferation inhibitory and proapoptotic abilities. However, they did not show proliferation inhibition ability on primary hepatocytes or HepG2 cells. Significant cell detachment was also observed in δ-tocopherol- and tocol-treated HSCs. Decreased protein expressions of α-smooth muscle actin and β1 integrin were observed in a dose-dependent manner. These results indicate that δ-tocopherol and tocol induce anoikis in activated HSCs.

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.

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.

The pathogenicity of an enteric Citrobacter rodentium Infection is enhanced by deficiencies in the antioxidants selenium and vitamin E

The pathogenesis of a Citrobacter rodentium infection was evaluated in mice fed diets with a single deficiency in either selenium or vitamin E or with a double deficiency in both selenium and vitamin E compared to mice on nutritionally adequate diets. Mice fed the selenium- and vitamin E-deficient diet for 6 weeks had increased loads of C. rodentium in the colon and spleen, which were not observed in mice fed either of the singly deficient diets or the adequate diet. Infected mice fed the doubly deficient diet had increased colon crypt hyperplasia and an influx of infiltrating cells along with gross changes to crypt architecture, including ulceration and denuding of the epithelial layer. Cytokine and chemokine mRNA levels in the colon were measured by real-time PCR. Expression of proinflammatory cytokines and chemokines was upregulated on day 12 after infection with C. rodentium in mice fed the doubly deficient diet compared to mice fed the control diet. Heme oxygenase 1, an enzyme upregulated by oxidative stress, also was more highly induced in infected mice fed the doubly deficient diet. Production of C. rodentium antigen-specific IgM and IgG antibodies was not affected by feeding the doubly deficient diet. The results indicated that selenium and vitamin E play an important role in host resistance and in the pathology induced by C. rodentium, an infection that mimics disease caused by common food-borne bacterial pathogens in humans.

Dietary supplementation with tocotrienols enhances immune function in C57BL/6 mice

alpha-Tocopherol (alpha-Toc) enhances T cell function, whereas little is known in this regard for tocotrienols (T3), the less-known members of the vitamin E family. We pair-fed young (4 mo) and old (23 mo) C57BL/6 mice 0.1% Tocomin 50%, a mixture of T3 and alpha-Toc or a control diet containing an equal amount of alpha-Toc for 6 wk. As expected, lymphocyte proliferation was lower in the old mice compared with the young mice. Lymphocyte proliferation in the old T3 group was significantly higher than that in the old control group, whereas no significant difference was found in young mice. Splenocytes from old mice produced less interleukin (IL)-2, IL-4, IL-6, and IL-10 compared with young mice, whereas no significant age-related difference was found in IL-1beta, tumor necrosis factor-alpha, and interferon-gamma. T3 feeding was associated with a higher IL-1beta production in old mice but not in young mice. Peritoneal macrophages from old mice produced significantly more IL-1beta, IL-6, IL-10, and prostaglandin E(2) (PGE(2)) compared with those from young mice. Mice of both ages fed T3 had higher production of IL-1beta but not PGE(2) or other cytokines. In the in vitro study, splenocytes isolated from young and old mice were supplemented with the purified form of each individual T3 (0.01-10 mumol/L) and mitogen-stimulated cell proliferation was determined. All T3 enhanced lymphocyte proliferation in old but not young mice with a potency order of alpha- > gamma- > delta-T3. Together, these results suggest a beneficial effect of T3 in improving the age-related decline in T cell function.

Impact of vitamin E on immune function and its clinical implications

Vitamin E is a chain-breaking antioxidant that protects membranes from free-radical damage. Evidence suggests significant impact of vitamin E on the modulation of immune functions. Results from animal and human studies indicate that vitamin E deficiency impairs both humoral and cell-mediated immune functions. Supplementation of vitamin E above the recommended levels has been shown to enhance immune functions and to be associated with increased resistance against several pathogens, especially in the aged. The current vitamin E consumption status from diets, the status of vitamin E supplement use, the effects of vitamin E on different aspects of immune functions and mechanisms of its action and the clinical significance of vitamin E supplementation will be reviewed.

Differential effects of natural and synthetic vitamin E on gene transcription in murine T lymphocytes

Mice were supplemented with low and high doses of natural and synthetic vitamin E, T cells from the spleen isolated and stimulated with plate-bound anti-CD3 and soluble anti-CD28, and gene expression changes assessed by gene array experiments. The data obtained indicate significant qualitative and quantitative differences between the two vitamin forms in regulating gene expression in response to T-cell stimulation. Marker genes have been found whose expression can be considered significant in establishing the level of, and response to vitamin E for both natural and synthetic vitamin E supplementation; unique markers for synthetic vitamin E supplementation and unique markers for natural vitamin E supplementation have been identified.

Reactive oxygen intermediate-induced pathomechanisms contribute to immunosenescence, chronic inflammation and autoimmunity

Deregulation of reactive oxygen intermediates (ROI) resulting in either too high or too low concentrations are commonly recognized to be at least in part responsible for many changes associated with aging. This article reviews ROI-dependent mechanisms critically contributing to the decline of immune function during physiologic - or premature - aging. While ROI serve important effector functions in cellular metabolism, signalling and host defence, their fine-tuned generation declines over time, and ROI-mediated damage to several cellular components and/or signalling deviations become increasingly prevalent. Although distinct ROI-associated pathomechanisms contribute to immunosenescence of the innate and adaptive immune system, mutual amplification of dysfunctions may often result in hyporesponsiveness and immunodeficiency, or in chronic inflammation with hyperresponsiveness/deregulation, or both. In this context, we point out how imbalanced ROI contribute ambiguously to driving immunosenescence, chronic inflammation and autoimmunity. Although ROI may offer a distinct potential for therapeutic targeting along with the charming opportunity to rescue from deleterious processes of aging and chronic inflammatory diseases, such modifications, owing to the complexity of metabolic interactions, may carry a marked risk of unforeseen side effects.

Comparison of the inhibitory effects of vitamin E analogues on melanogenesis in mouse B16 melanoma cells

The effect of eight vitamin E analogues (d-alpha-, dl-alpha-, d-beta-, d-gamma-, and d-delta-tocopherols, d-alpha- and dl-alpha-tocopheryl acetates) and 2,2,5,7,8-pentamethyl-6-hydroxychroman (PMC) on melanogenesis were compared in mouse B16 melanoma cells. D-beta-tocopherol at 250 mug ml(-1) inhibited not only 28% of melanin synthesis in B16 cells, but also 34% of the tyrosinase activity, a very important cascade enzyme involved in the synthesis of melanin in melanoma cells. D-gamma-tocopherol also strongly inhibited up to 39% of melanin synthesis and 45% of the tyrosinase enzyme activity at the same concentration. The inhibitory activity of both d-beta- and d-gamma-tocopherols was observed without cytotoxicity up to a concentration of 250 mug ml(-1). Weak activity was also observed with d-delta-tocopherol at 8 mug ml(-1) and with PMC at 16 mug ml(-1), with 19% and 25% inhibition of melanin synthesis, respectively. However, PMC did not directly inhibit tyrosinase, as was observed with d-beta-, d-gamma-, and d-delta-tocopherols. Analysis by reverse transcription-polymerase chain reaction showed that the mechanism of melanogenesis inhibition by d-beta- and d-gamma-tocopherols in cells might be attributed to reduced expression of tyrosinase and tyrosinase related protein-2 mRNA in addition to direct inhibition of the tyrosinase. These findings suggest that both d-beta-tocopherol and d-gamma-tocopherol might be useful as effective ingredients in whitening cosmetics with lower skin toxicity to prevent or improve skin pigmentation such as skin spots and freckles caused by UV exposure.

Dietary beta-tocopherol and linoleic acid, serum insulin, and waist circumference predict circulating sex hormone-binding globulin in premenopausal women

Reduced levels of circulating sex hormone-binding globulin (SHBG) are implicated in the etiology of sex steroid-related pathologies and the metabolic syndrome. Dietary correlates of serum SHBG remain unclear and were studied in a convenient cross-sectional sample of healthy 30- to 40-y-old women (n = 255). By univariate analyses, serum SHBG correlated negatively with several indices of the metabolic syndrome, such as BMI, waist circumference, hip circumference (r = -0.36 to -0.44; P < 0.0001), fasting serum insulin (r = -0.41; P < 0.0001), serum triglycerides (r = -0.27; P < 0.0001), serum glucose (r = -0.23; P < 0.001), and plasma testosterone (r = -0.19; P = 0.002). Serum SHBG correlated positively with serum HDL-cholesterol (r = 0.33; P < 0.0001), plasma progesterone (r = 0.17; P = 0.007), and dietary intake of beta-tocopherol (r = 0.17; P = 0.006), and negatively with that of fructose (r = -0.13; P = 0.04). Principal component analysis (PCA) extracted 12 nutrient factors with eigenvalues > 1.0 from 54 nutrients and vitamins in food records. Multivariate regression analyses showed that the PCA-extracted nutrient factor most heavily loaded with beta-tocopherol and linoleic acid (P = 0.03) was an independent positive predictor of serum SHBG. When individual nutrients were the predictor variables, beta-tocopherol (P = 0.002), but not other tocopherols or fatty acids (including linoleic acid), was an independent positive predictor of serum SHBG. Circulating insulin (P = 0.02) and waist circumference (P = 0.002), but not serum lipids, were negative independent predictors of SHBG in all regression models. Additional studies are needed in women of other age groups and men to determine whether consumption of foods rich in beta-tocopherol and/or linoleic acid may increase serum SHBG concentrations and may thereby decrease the risk for metabolic syndrome and reproductive organ cancer.

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.

Elevated plasma gamma-tocopherol and decreased alpha-tocopherol in men are associated with inflammatory markers and decreased plasma 25-OH vitamin D

Chronic inflammation is a risk factor for many diseases of aging. Endogenous oxidants are thought to mediate the effects of inflammation and gamma-Tocopherol (gamma-Toc) may mitigate damage from nitrogen-based oxidants; however, no physiological requirement for gamma-Toc has been established. Regulation of tocopherols and their functional significance are poorly defined, thereby limiting their application in prevention. Using stored plasma samples from 657 male control subjects in a previous study of prostate cancer, we have analyzed associations of the tocopherols, inflammation markers, and 25-hydroxy (OH) vitamin D. Plasma alpha-Toc and gamma-Toc were inversely correlated, whereas delta-Toc and alpha-Toc levels were positively correlated, suggesting a unique regulatory mechanism. gamma-Toc levels were positively and alpha-Toc negatively associated with plasma C-reactive protein (CRP) and urinary isoprostane F(2t), which are markers of inflammation and oxidation. Ethnic variability in tocopherols was observed; however, this may be explained by differences in plasma 25-OH vitamin D, as gamma-Toc levels varied inversely and alpha-Toc positively with 25-OH vitamin D. In these data, all-cause mortality appeared to be positively associated with CRP and inversely with 25-OH vitamin D. We hypothesize that plasma levels of tocopherols may serve as markers of systemic inflammation, complicating epidemiologic assessment of their role in cancer etiology.

The role of vitamin E in reversing bone loss

BACKGROUND AND AIMS

A positive correlation between intake of antioxidants including vitamins E and C on bone mass has been established by a number of investigators. The present study was conducted to evaluate the extent to which higher doses of vitamin E than normal dose (75 IU per kg diet) can reverse bone loss in aged osteopenic orchidectomized male rats.

METHODS

Forty 12-month old male Sprague- Dawley rats were either sham-operated (Sham) or orchidectomized (Orx), and fed control diet for 120 days to establish bone loss. Thereafter, rats were assigned to their corresponding treatment groups (n= 10 per group): Sham and one Orx groups received 75 IU vitamin E and served as controls, and the other two Orx groups received either 250 or 500 IU vitamin E per kg diet for 90 days.

RESULTS

Higher doses of vitamin E did not improve bone mineral density (BMD) or content (BMC) of whole body, femur and lumbar vertebra or alter the orchidectomy-induced deterioration of trabecular microarchitecture of the distal femur metaphysis in comparison with Orx controls that received adequate vitamin E. Biochemical markers of bone formation and bone resorption, i.e. serum osteocalcin and urinary deoxypyridinoline crosslinks, were also unaffected by vitamin E supplementation.

CONCLUSIONS

Overall, the findings of the present study suggest that supplemental doses of vitamin E do not increase BMD values in male rat model of osteoporosis. However, human studies are needed to confirm the population findings indicating that individuals with higher vitamin E intake have higher bone mass.

Antigen sparing and cross-reactive immunity with an adjuvanted rH5N1 prototype pandemic influenza vaccine: a randomised controlled trial

BACKGROUND

Antigen sparing is regarded as crucial for pandemic vaccine development because worldwide influenza vaccine production capacity is limited. Adjuvantation is an important antigen-sparing strategy. We assessed the safety and immunogenicity of a recombinant H5N1 split-virion vaccine formulated with a proprietary adjuvant system and investigated whether it can induce cross-reactive immunity.

METHODS

Two doses of an inactivated split A/Vietnam/1194/2004 NIBRG-14 (recombinant H5N1 engineered by reverse genetics) vaccine were administered 21 days apart to eight groups of 50 volunteers aged 18-60 years. We studied four antigen doses (3.8 microg, 7.5 microg, 15 microg, and 30 microg haemagglutinin) given with or without adjuvant. Blood samples were collected to analyse humoral immune response. Adverse events were recorded up through study day 51. Safety analyses were of the whole vaccinated cohort and immunogenicity analyses per protocol. This trial is registered with the ClinicalTrials.gov, number NCT00309634.

FINDINGS

All eight vaccine formulations had a good safety profile. No serious adverse events were reported. The adjuvanted vaccines induced more injection-site symptoms and general symptoms than did the non-adjuvanted vaccines, but most were mild to moderate in intensity and transient in nature. The adjuvanted formulations were significantly more immunogenic than the non-adjuvanted formulations at all antigen doses. At the lowest antigenic dose (3.8 microg), immune responses for the adjuvanted vaccine against the recombinant homologous vaccine strain (A/Vietnam/1194/2004 NIBRG-14, clade 1) met or exceeded all US Food and Drug Administration and European Union licensure criteria. Furthermore, 37 of 48 (77%) participants receiving 3.8 microg of the adjuvanted vaccine seroconverted for neutralising antibodies against a strain derived by reverse genetics from a drifted H5N1 isolate (A/Indonesia/5/2005, clade 2).

INTERPRETATION

Adjuvantation conferred significant antigen sparing that could increase the production capacity of pandemic influenza vaccine. Moreover, the cross-clade neutralising antibody responses recorded imply that such a vaccine could be deployed for immunisation before a pandemic.

Enhancement of intracellular gamma-tocopherol levels in cytokine-stimulated C3H 10T1/2 fibroblasts: relation to NO synthesis, isoprostane formation, and tocopherol oxidation

Background

Stimulation of C3H 10T1/2 murine fibroblasts with interferon-γ(IFN) and bacterial lipopolysaccharide (LPS) generates reactive oxygen and nitrogen species leading to DNA damage, lipid oxidation, and tocopherol oxidation. The tocopherols possess unique chemical and biological properties that suggest they have important roles related to intracellular defense against radical-mediated damage.

Results

Despite increased levels of reactive oxidants and decreased media tocopherol, cellular levels of γ-tocopherol, but not α-tocopherol, were observed to increase significantly when cells were treated with IFN/LPS. Inhibition of nitric oxide (NO) synthesis by a specific inhibitor of inducible NO synthase (iNOS) increased both intracellular α-tocopherol and γ-tocopherol concentrations, but did not significantly alter the reduction in media tocopherol levels caused by IFN/LPS treatment. Both exposure to exogenous NO and cellular synthesis of NO in cell culture increased media levels of 8-epi-prostaglandin F2α, a marker of oxidative lipid damage, whereas inhibition of endogenous NO synthesis reduced media 8-epi-prostaglandin F2α formation to control levels.

Conclusion

Elevated intracellular levels of γ-tocopherol in response to the cellular inflammatory state may indicate that it serves a unique role in minimizing cellular damage resulting from endogenous NO synthesis. Results of the current study suggest that NO is an important mediator of damage within the cell, as well as in the oxidation of both α- and γ-tocopherols. The paradoxical increase in cellular tocopherol associated with the induction of NO synthesis may indicate either enhanced cellular transport/decreased export for tocopherols or recruitment of free tocopherol from tocopherol storage molecules.

Vitamins C and E prevent AZT-induced leukopenia and loss of cellularity in bone marrow. Studies in mice

A major limitation in the use of AZT for AIDS treatment is the occurrence of side effects, such as leukopenia. The effects of antioxidant vitamins C and E on AZT-induced leukopenia were investigated in mice. Mice were divided into four groups: (1) controls; (2) AZT-treated; (3) treated with AZT plus vitamins C and E; and (4) pre-treated with vitamins and then treated with AZT plus vitamins. Our results demonstrate that AZT causes leukopenia in mice, which was abrogated by administration of vitamins C and E in the pre-treated group. These vitamins prevented the decrease in cellular content induced by AZT in bone marrow and diminished peroxide levels in myeloid precursors in bone marrow. AZT also caused an increase in plasma malondialdehyde and blood oxidized glutathione levels, which was prevented by the administration of antioxidant vitamins. In conclusion, oxidative stress is involved in AZT-induced leukopenia which may be prevented by antioxidant treatment.

Age-associated decline in effective immune synapse formation of CD4(+) T cells is reversed by vitamin E supplementation

Aging is associated with reduced IL-2 production and T cell proliferation. Vitamin E supplementation, in aged animals and humans, increases cell division and IL-2 production by naive T cells. The immune synapse forms at the site of contact between a T cell and an APC and participates in T cell activation. We evaluated whether vitamin E affects the redistribution of signaling proteins to the immune synapse. Purified CD4(+) T cells, from the spleens of young and old mice, were treated with vitamin E before stimulation with a surrogate APC expressing anti-CD3. Using confocal fluorescent microscopy, we observed that CD4(+) T cells from old mice were significantly less likely to recruit signaling proteins to the immune synapse than cells from young mice. Vitamin E increased the percentage of old CD4(+) T cells capable of forming an effective immune synapse. Similar results were found following in vivo supplementation with vitamin E. When compared with memory cells, naive T cells from aged mice were more defective in immune synapse formation and were more responsive to vitamin E supplementation. These data show, for the first time, that vitamin E significantly improves age-related early T cell signaling events in naive CD4(+) T cells.

Anti-inflammatory properties of alpha- and gamma-tocopherol

Natural vitamin E consists of four different tocopherol and four different tocotrienol homologues (alpha,beta, gamma, delta) that all have antioxidant activity. However, recent data indicate that the different vitamin E homologues also have biological activity unrelated to their antioxidant activity. In this review, we discuss the anti-inflammatory properties of the two major forms of vitamin E, alpha-tocopherol (alphaT) and gamma-tocopherol (gammaT), and discuss the potential molecular mechanisms involved in these effects. While both tocopherols exhibit anti-inflammatory activity in vitro and in vivo, supplementation with mixed (gammaT-enriched) tocopherols seems to be more potent than supplementation with alphaT alone. This may explain the mostly negative outcomes of the recent large-scale interventional chronic disease prevention trials with alphaT only and thus warrants further investigation.

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.

Vitamin E and C supplementation prevents decrease of eicosapentaenoic acid in mononuclear cells in chronic hepatitis C patients during combination therapy of interferon alpha-2b and ribavirin

OBJECTIVE

We investigated the effects of vitamin E and C supplementation on the fatty acid composition of mononuclear cells and on the clinical observations in patients who had chronic hepatitis C and received interferon-alpha-2b (IFN-alpha-2b) and ribavirin combination therapy.

METHODS

Patients were randomly allocated to receive daily 500 mg of vitamin E and 750 mg of vitamin C (vitamin group, n = 14) or no supplement (non-vitamin group, n = 16) in addition to IFN-alpha-2b and ribavirin therapy. The fatty acid composition of mononuclear cell phospholipids was analyzed before and at 2, 4, and 8 wk after treatment.

RESULTS

After vitamin supplementation, plasma and red blood cell alpha-tocopherol and plasma ascorbic acid levels increased in the vitamin group. Serum levels of alanine aminotransferase decreased significantly after 2 wk of treatment in both groups. At the start of treatment, a lower level of eicosapentaenoic acid (EPA) and a higher level of the molar ratio of arachidonic acid to EPA in mononuclear cells were observed in the present patients compared with healthy volunteers, and a significant correlation between the molar ratio and serum alanine aminotransferase level was found. The EPA level of mononuclear cells was maintained in the vitamin group during treatment, whereas a significant decrease was observed in the non-vitamin group at 4 and 8 wk after treatment.

CONCLUSIONS

Antioxidant vitamin supplementation during IFN-alpha-2b and ribavirin therapy prevented a decrease in EPA of mononuclear cell phospholipids. If a further decrease in the ratio of arachidonic acid to EPA can be achieved by using oral EPA supplementation, the efficacy of IFN-alpha-2b and ribavirin therapy may be improved.

Low and high levels of α-tocopherol exert opposite effects on IL-2 possibly through the modulation of PPAR-γ, IκBα, and apoptotic pathway in activated splenocytes

OBJECTIVE

We previously demonstrated that a high dose of alpha-tocopheryl succinate inhibits interleukin-2 (IL-2) mRNA and production in autoimmune-prone MRL/lpr mice. In the present study, we investigated the regulation of alpha-tocopherol (alphaTOC) on IL-2 gene expression by examining the mRNA of IL-2, inhibitor kappaBalpha (IkappaBalpha), and peroxisome proliferator-activated receptor-gamma (PPARgamma).

METHODS

Messenger RNA expression in active splenocytes of BALB/c mice was investigated with reverse transcriptase polymerase chain reaction.

RESULTS

Levels of IL-2 mRNA in phorbol 12-myristate 13-acetate/ionomycin activated splenocytes and cytokine in T-helper-1 cells were increased by 50 microM of alphaTOC but decreased by 1 mM of alphaTOC. In addition, the IkappaBalpha gene expression significantly increased by the high dose (>or=500 microM) of alphaTOC, suggesting an inhibition on nuclear factor-kappaB pathway for activation of IL-2 expression. PPARgamma mRNA level in activated splenocytes was upregulated by 1 mM of alphaTOC. PPARgamma mRNA level in unstimulated splenocytes was upregulated by alphaTOC in a dose-dependent manner, suggesting that alphaTOC might enhance the PPARgamma signaling pathway. High-dose alphaTOC induced apoptosis of splenocytes and inhibited phytohemagglutinin-stimulated T-cell proliferation. Conversely, the proliferative response of splenocytes was enhanced by 5 microM of alphaTOC. Low-dose (50 microM) alphaTOC increased IL-2 expression, which may have been due to the absence of downregulation of PPARgamma and IkappaBalpha on the IL-2 gene.

CONCLUSION

The results indicated that low and high doses of alphaTOC exert opposite effects on IL-2, possibly through modulation of PPARgamma, IkappaBalpha, and apoptosis pathways. The present findings support our previous observation of opposite effects of low- and high-dose vitamin E on survival of MRL/lpr mice.

Vitamin E and immune response in the aged: molecular mechanisms and clinical implications

Nutritional status has been indicated as a contributing factor to age-related dysregulation of the immune response. Vitamin E, a lipid-soluble antioxidant vitamin, is important for normal function of the immune cells. The elderly are at a greater risk for vitamin E intake that is lower than recommended levels. Vitamin E supplementation above currently recommended levels has been shown to improve immune functions in the aged including delayed-type hypersensitivity skin response and antibody production in response to vaccination, which was shown to be mediated through increased production of interleukin (IL)-2, leading to enhanced proliferation of T cells, and through reduced production of prostaglandin E(2), a T-cell suppressive factor, as a result of a decreased peroxynitrite formation. Vitamin E increased both cell-dividing and IL-producing capacities of naive T cells, but not memory T cells. The vitamin E-induced enhancement of immune functions in the aged was associated with significant improvement in resistance to influenza infection in aged mice and a reduced risk of acquiring upper respiratory infections in nursing home residents. Further studies are needed to determine the signaling mechanisms involved in the upregulation of naive T-cell function by vitamin E as well as the specific mechanisms involved in reduction of risk for upper respiratory infections.

Deficiencies in selenium and/or vitamin E lower the resistance of mice to Heligmosomoides polygyrus infections

Previous studies have shown that deficiencies in selenium (Se) and/or vitamin E (VE) can exacerbate the infectivity and pathogenesis of coxsackievirus B3 and influenza. Both Se and VE play a role in immune function and antioxidant defense. To determine whether these deficiencies would affect the normal course of infection with a metazoan parasite, mice were made deficient in Se and/or VE and inoculated with the gastrointestinal nematode parasite Heligmosomoides polygyrus. Both primary and secondary infections were assessed. Although the course of a primary infection with H. polygyrus was unaffected by diet, diets deficient in Se, VE, and both Se and VE (Se/VE double-deficiency) all caused delayed adult worm expulsion and increased fecundity during a secondary infection; suggesting an impaired intestinal response. H. polygyrus-induced IL-4 levels were diet-independent; but Se/VE double-deficiency blocked the H. polygyrus-induced IL-4 receptor-associated decrease in sodium-dependent glucose absorption in the jejunum that contributes to worm expulsion. In contrast, Se/VE double-deficiency had no effect on the infection-induced, IL-4R-associated increase in epithelial cell permeability that accompanies the infection. These results suggest that both Se and VE are required for specific IL-4-related changes in intestinal physiology that promote host protection against H. polygyrus.

Effect of flavonoids and vitamin E on cyclooxygenase-2 (COX-2) transcription

Cyclooxygenase-2 (COX-2)-catalysed synthesis of prostaglandin E2 plays a key role in inflammation and its associated diseases, such as cancer and cardiovascular disease. There are numerous reports demonstrating that flavonoids inhibit COX-2 activity. However, transcriptional regulation of COX-2 can also be important. Nobiletin, amentoflavone, quercetin, quercetin penta-acetate, flavone, resveratrol, apigenin, chrysin, kaempferol, galangin, and genistein have been reported to modulate COX-2 transcription in a wide variety of systems. Here, we briefly review the literature on regulation of COX-2 transcription by flavonoids, and report some new preliminary data on Vitamin E and quercetin conjugates. Quercetin, quercetin 3-glucuronide, quercetin 3'-sulfate and 3'methylquercetin 3-glucuronide reduced COX-2 mRNA expression in both unstimulated and interleukin-1beta stimulated colon cancer (Caco2) cells. Quercetin and quercetin 3'-sulfate, unlike quercetin 3-glucuronide and 3'methylquercetin 3-glucuronide, also inhibited COX-2 activity. In contrast, tocopherols (alpha-tocopherol, alpha-tocopherol acetate, and gamma-tocopherol at 10microM) did not affect COX-2 mRNA expression in unstimulated Caco2 cells. However, the tocopherols inhibited COX-2 activity showing that the tocopherols act post-transcriptionally on activity, whereas quercetin and some quercetin conjugates affect both the transcription and activity of COX-2. Flavonoid modulation of COX-2 transcription may therefore be an important mechanism in anti-carcinogenesis.

Vitamin E supplementation increases polyunsaturated fatty acids of RBC membrane in HCV-infected patients

OBJECTIVE

We investigated the effects of vitamin E supplementation on the fatty acid composition of red blood cell membrane phospholipids and on the clinical observations in patients with hepatitis C virus.

METHOD

Eight patients and control subjects were administered 500 mg/d of d-alpha-tocopherol for 12 wk. The alpha-tocopherol and fatty acid composition of phospholipids in red blood cells were analyzed before, at 4, 8, and 12 wk, and after 4 wk of washout of vitamin E administration.

RESULTS

The alpha-tocopherol concentration in red blood cells increased 2.37-fold of the basal level during vitamin E supplementation. Serum alanine aminotransferase levels increased in five of eight patients with vitamin E supplementation. The arachidonic acid level, docosahexaenoic acid level, and ratio of polyunsaturated to saturated fatty acid in red blood cell membrane phospholipids, which were significantly lower in the patients than in the control subjects, were elevated at 8 and 12 wk after vitamin E supplementation. The improvement in fatty acid composition was observed particularly in the patients who responded to the vitamin E therapy.

CONCLUSIONS

Vitamin E therapy for the prevention of disease progression in patients with hepatitis C virus may be effective.

Vitamin E (alpha-tocopherol) attenuates cyclo-oxygenase 2 transcription and synthesis in immortalized murine BV-2 microglia

One of the immediate early microglial genes that are up-regulated in response to proinflammatory stimuli is cyclo-oxygenase 2 (COX-2). In the present study, we have investigated the effects of alpha-tocopherol (alpha TocH), an essential constituent of the nervous system, on the activation of COX-2 in lipopolysaccharide (LPS)-stimulated mouse BV-2 microglia. In unstimulated BV-2 cells, COX-2 mRNA and protein were almost undetectable but were strongly up-regulated in response to LPS. Activation of COX-2 protein synthesis in LPS-stimulated BV-2 cells involved activation of the extracellular-signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) pathway and was sensitive to the protein kinase C (PKC) inhibitors staurosporine and chelerythrine, and the MAP kinase/ERK kinase 1/2 inhibitors PD98059 and U0126. Supplementation of BV-2 cells with alpha TocH before LPS stimulation resulted in pronounced up-regulation of protein phosphatase 2A (PP2A) activity, down-regulation of PKC activity, ERK1/2 phosphorylation and nuclear factor kappa B (NF kappa B) activation. As a result, COX-2 protein levels and prostaglandin E(2) production were significantly lower in alpha TocH-supplemented cells. The effects of alpha TocH on PKC activity could be reverted by calyculin A and okadaic acid, two PP inhibitors. In summary, our results suggest that alpha TocH activates microglial PP2A activity and thereby silences an LPS-activated PKC/ERK/NF kappa B signalling cascade resulting in significantly attenuated COX-2 protein synthesis. These in vitro results imply that alpha TocH could induce quiescence to pathways that are associated with acute or chronic inflammatory conditions in the central nervous system.

Vitamin E improves bone quality in the aged but not in young adult male mice

It is generally viewed that with advancing age, humans and other animals including mice experience a gradual decline in the rate of bone formation. This, in part, may be due to the rise in oxygen-derived free radical formation. Vitamin E, a strong antioxidant, functions as a free radical scavenger that potentially can suppress bone resorption while stimulating bone formation. Although the effects of vitamin E on immune functions are well documented, there is a paucity of information on its effect on skeletal health in vivo. The purpose of this study was to explore the influence of vitamin E supplementation on bone in young adult and old mice. Six and twenty-four month-old male C57BL/6NIA mice each were divided into two groups and fed a diet containing either adequate (30 mg/kg diet) or high (500 mg/kg diet) levels of vitamin E. Thirty days later, mice were killed and bones were removed for analyses including biomechanical testing using three-point bending and mRNA expressions of insulin-like growth factor-I (IGF-I), osteocalcin, and type 1alpha-collagen using Northern blot. In old but not the young adult mice, high-dose vitamin E enhanced bone quality as evident by improved material and structural bone properties in comparison with adequate. This improved quality was accompanied by increases in bone dry weight, protein, and mRNA transcripts for osteocalcin, type Ialpha-collagen, and IGF-I. These data demonstrate that high-dose vitamin E has pronounced effects on bone quality as well as matrix protein in old mice by augmenting bone matrix protein without reducing bone mineralization as evidenced by unaltered bone density.

Mixed tocopherols have a stronger inhibitory effect on lipid peroxidation than alpha-tocopherol alone

Intake of vitamin E with food (mixed tocopherols) has been found to counteract the development of atherosclerotic cardiovascular disease, whereas intake of large amounts of pure alpha-tocopherol has shown only a slight or no effect in clinical studies. This study was designed to investigate the effects of alpha-tocopherol alone and a mixed tocopherol preparation (gamma-, delta-, and alpha-tocopherol) on hydrogen peroxide-induced lipid peroxidation in human erythrocytes. Erythrocytes were incubated with different concentrations of alpha-tocopherol or mixed tocopherols and then exposed to hydrogen peroxide. Tocopherol levels and malondialdehyde-thiobarbituric acid-reactive substances were determined by high-performance liquid chromatography and fatty acids by gas chromatography. Incubation of erythrocytes with tocopherols (30-120 microM) increased the tocopherol level in a concentration-dependent manner. The uptake of gamma- and delta-tocopherols was much higher than that of alpha-tocopherol. Hydrogen peroxide strongly increased lipid peroxidation and decreased polyunsaturated fatty acids in erythrocytes. Both alpha-tocopherol and the tocopherol mixture protected the cells from lipid peroxidation, the mixture being much more potent than alpha-tocopherol alone. This study indicates that a mixture of tocopherols has a stronger inhibitory effect on lipid peroxidation induced in human erythrocytes than alpha-tocopherol alone, due to higher uptake of gamma- and delta-tocopherol in the cells.

Mechanism of vitamin E inhibition of cyclooxygenase activity in macrophages from old mice: role of peroxynitrite

Vitamin E inhibits cyclooxygenase activity in macrophages from old mice by reducing peroxynitrite production. PGE(2) is a proinflammatory mediator that has been linked to a variety of age-associated diseases such as cancer, arthritis, and cardiovascular disease. Furthermore in the aged, increased cyclooxygenase (COX)-2-mediated PGE(2) production contributes to decline in T-cell-mediated function. Previously we reported that increased macrophage PGE(2) production in the aged is due to higher COX-2 activity and that supplementation with vitamin E significantly reduced the age-associated increase in macrophage PGE(2) production posttranslationally without changing COX-2 expression. Peroxynitrite, a product of nitric oxide (NO) and superoxide (O(-)(2)), increases the activity of COX without affecting its expression. Thus, we investigated if vitamin E inhibits COX activity through decreasing peroxynitrite formation. Macrophages from old mice had higher PGE(2) levels, COX activity, and NO levels than those from young mice, all of which were significantly reduced by vitamin E. When added individually, inhibitors of NO and O(-)(2) did not significantly reduce COX activity; however, when the inhibitors were combined, COX activity was significantly reduced in macrophages from old mice fed 30 ppm vitamin E. Increasing NO levels alone using SNAP or O(-)(2) levels, using X/XO, had no effect; however, increasing peroxynitrite levels using Sin-1 or X/XO + SNAP significantly increased COX activity in macrophages from old mice fed 500, but not those fed 30 ppm vitamin E. These data strongly suggest that peroxynitrite plays an important role in the vitamin E-induced inhibition of COX activity. These findings have important implications for designing interventions to reverse and/or delay age-associated dysregulation of immune and inflammatory responses and diseases associated with them.

Modulation of human lymphocyte proliferative response with aging

Previously, we have demonstrated age-associated alterations in transmembrane signaling. One of the most reproducible alterations found in the immune response with aging is the decrease of lymphocyte proliferation on stimulation with various different mitogens. Here, we confirm that proliferative responses to stimulation with phytohaemagglutin (PHA), recombinant human IL-2, or anti-CD3 monoclonal antibody are all greater in the young (20-25 years) than old (60-87 years) population. We attempted to modulate the proliferative response using various agents acting at different levels of transmembrane signaling (pertussis toxin, cholera toxin, isoproterenol, PMA, Ca ionophore A23187), as well as at the level of the lymphocyte plasma membrane (methyl-beta-cyclodextrin, MBCD), or by using antioxidant vitamins (Vitamin E or C). None of these agents was able to restore effectively the proliferative response of lymphocytes from the aged to the level of young subjects. Even the combination of A23187 and PMA acting directly on calcium metabolism and protein kinase C activity was insufficient to restore the decreased mitogenic capacity of T cells from elderly subjects. Cyclodextrin, which decreases the cholesterol content of the membrane, increased the proliferative response of lymphocytes of elderly subjects, but not to the level of the young. Vitamin E had a very strong inhibitory effect on lymphocyte stimulation in both the age groups, except in combination with MBCD in T cells of the elderly, while Vitamin C had no significant modulatory effect. MAPK ERK and p38 activation was found to be decreased with aging in T cells after anti-CD3 mAb stimulation. Vitamin E but not Vitamin C strongly inhibited MAPK ERK or p38 activation. The direct activation of certain molecules or the modulation of the cholesterol content of the membrane seems to be effective immunomodulatory interventions with aging.

Nutritional strategies to boost immunity and prevent infection in elderly individuals

Older adults are at risk for malnutrition, which may contribute to their increased risk of infection. Nutritional supplementation strategies can reduce this risk and reverse some of the immune dysfunction associated with advanced age. This review discusses nutritional interventions that have been examined in clinical trials of older adults. The data support use of a daily multivitamin or trace-mineral supplement that includes zinc (elemental zinc, >20 mg/day) and selenium (100 microg/day), with additional vitamin E, to achieve a daily dosage of 200 mg/day. Specific syndromes may also be addressed by nutritional interventions (for example, cranberry juice consumption to reduce urinary tract infections) and may reduce antibiotic use in older adults, particularly those living in long-term care facilities. Drug-nutrient interactions are common in elderly individuals, and care providers should be aware of these interactions. Future research should evaluate important clinical end points rather than merely surrogate markers of immunity.

Vitamin E-enhanced IL-2 production in old mice: naive but not memory T cells show increased cell division cycling and IL-2-producing capacity

Aging is associated with reduced T cell function, as demonstrated by decreased T cell proliferation and IL-2 production. These changes respond to supplemental vitamin E both in animals and humans, in part by the reduction of T cell suppressive PGE(2), the production of which by macrophages is increased with age. To evaluate whether vitamin E has a direct PGE(2)-independent effect on T cell responses, T cells purified from the spleens of young and old mice were preincubated with vitamin E or vehicle control. Activation-induced cell division of T cells from old mice was lower than that by young, and the production of IL-2 following 48-h activation was less by T cells from old mice. There was an age-related decline in both the number of IL-2+ T cells and the amount of IL-2 produced per cell. Despite decreased IL-2 protein at 48 h, the expression of IL-2 mRNA at 6 h and IL-2 protein production at 6 and 16 h was greater by T cells from old mice compared with that of young. Age-related decline in cell division and IL-2 production at 48 h was only observed within the naive T cell subpopulation. Vitamin E increased both cell-dividing and IL-2-producing capacity of naive T cells from old mice, with no effect on memory T cells. These data indicate that naive T cells exhibit the greatest age-related defect and show for the first time that supplemental vitamin E has direct immunoenhancing effect on naive T cells from old mice.

Vitamin E and macrophage cyclooxygenase regulation in the aged

Aging is associated with increased evidence of cardiovascular disease (CVD). Atherosclerosis, a major cause of CVD, is an inflammatory process whose development is influenced by several proinflammatory mediators. Products of arachidonic acid metabolism, in particular, prostaglandin (PG) E(2) and thromboxane (TX) A(2), play an important role in the development of atherosclerosis. We showed previously that the aged have higher PGE(2) production compared with their young counterparts. This age-associated increase in PGE(2) production is mainly a consequence of increased cyclooxygenase (COX) activity. We demonstrated further that increased COX activity in old mice is due to the increased expression of mRNA and protein for the inducible form of COX, COX-2. Vitamin E has been shown to reduce PGE(2) production and risk of CVD. In aged mice, we showed that a vitamin E-induced decrease in PGE(2) production is due to decreased COX activity. However, vitamin E had no effect on COX mRNA and protein levels, indicating a post-translational regulation of COX by vitamin E. Further experiments indicated that vitamin E decreases COX activity through reducing formation of peroxynitrite, a hydroperoxide shown to be involved in the activation of COX-2. Other homologues of tocopherols were also effective in inhibiting COX activity, but their degree of inhibition varied. The varied potency to inhibit COX activity was not explained totally by differences in their antioxidant capacity. Vitamin E-induced inhibition of COX activity might contribute to its effect of reducing CVD risk.

gamma-tocopherol and its major metabolite, in contrast to alpha-tocopherol, inhibit cyclooxygenase activity in macrophages and epithelial cells

Cyclooxygenase-2 (COX-2)-catalyzed synthesis of prostaglandin E(2) (PGE(2)) plays a key role in inflammation and its associated diseases, such as cancer and vascular heart disease. Here we report that gamma-tocopherol (gammaT) reduced PGE(2) synthesis in both lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and IL-1beta-treated A549 human epithelial cells with an apparent IC(50) of 7.5 and 4 microM, respectively. The major metabolite of dietary gammaT, 2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), also exhibited an inhibitory effect, with an IC(50) of approximately 30 microM in these cells. In contrast, alpha-tocopherol at 50 microM slightly reduced (25%) PGE(2) formation in macrophages, but had no effect in epithelial cells. The inhibitory effects of gammaT and gamma-CEHC stemmed from their inhibition of COX-2 activity, rather than affecting protein expression or substrate availability, and appeared to be independent of antioxidant activity. gamma-CEHC also inhibited PGE(2) synthesis when exposed for 1 h to COX-2-preinduced cells followed by the addition of arachidonic acid (AA), whereas under similar conditions, gammaT required an 8- to 24-h incubation period to cause the inhibition. The inhibitory potency of gammaT and gamma-CEHC was diminished by an increase in AA concentration, suggesting that they might compete with AA at the active site of COX-2. We also observed a moderate reduction of nitrite accumulation and suppression of inducible nitric oxide synthase expression by gammaT in lipopolysaccharide-treated macrophages. These findings indicate that gammaT and its major metabolite possess anti-inflammatory activity and that gammaT at physiological concentrations may be important in human disease prevention.