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

The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities

Dietary selenium (]Se), mainly through its incorporation into selenoproteins, plays an important role in inflammation and immunity. Adequate levels of Se are important for initiating immunity, but they are also involved in regulating excessive immune responses and chronic inflammation. Evidence has emerged regarding roles for individual selenoproteins in regulating inflammation and immunity, and this has provided important insight into mechanisms by which Se influences these processes. Se deficiency has long been recognized to negatively impact immune cells during activation, differentiation, and proliferation. This is related to increased oxidative stress, but additional functions such as protein folding and calcium flux may also be impaired in immune cells under Se deficient conditions. Supplementing diets with above-adequate levels of Se can also impinge on immune cell function, with some types of inflammation and immunity particularly affected and sexually dimorphic effects of Se levels in some cases. In this comprehensive article, the roles of Se and individual selenoproteins in regulating immune cell signaling and function are discussed. Particular emphasis is given to how Se and selenoproteins are linked to redox signaling, oxidative burst, calcium flux, and the subsequent effector functions of immune cells. Data obtained from cell culture and animal models are reviewed and compared with those involving human physiology and pathophysiology, including the effects of Se levels on inflammatory or immune-related diseases including anti-viral immunity, autoimmunity, sepsis, allergic asthma, and chronic inflammatory disorders. Finally, the benefits and potential adverse effects of intervention with Se supplementation for various inflammatory or immune disorders are discussed.

Effects of soybean peptide on immune function, brain function, and neurochemistry in healthy volunteers

OBJECTIVE

Soybeans, an excellent source of dietary peptides, have beneficial effects on health. We investigated the effect of the soybean peptide on immune function, brain function, and neurochemistry in healthy volunteers.

METHODS

Near-infrared spectroscopy (NIRS) was used to analyze brain cerebral blood flow. The A and DA levels in the serum were analyzed by ELISA kit. The total number of leukocytes was recorded with a standard counter. Flow cytometry was used to assess lymphocyte subset levels.

RESULTS

Cell numbers were upregulated in the group that had fewer leukocytes but downregulated in the group with more leukocytes. For the lymphocyte-rich type, lymphocyte counts tended to decrease, accompanied by an increase in granulocyte numbers. For the granulocyte-rich type, granulocyte counts tended to increase, but lymphocyte counts also increased. The numbers of CD11b(+) cells and CD56(+) cells increased significantly. Soybean peptide decreased the adrenalin level in plasma but increased the level of dopamine. Near-infrared spectroscopy showed significant increases in the amplitudes of θ, α-2, and β-L frequency bands after the ingestion of peptides.

CONCLUSION

Soybean peptides can modulate cellular immune systems, regulate neurotransmitters, and boost brain function.

Vitamin E, signalosomes and gene expression in T cells

CD4+T cells from aged humans or mice show significant reductions in IL-2 production upon activation. The resulting decreased proliferation is linked to higher risks of infection in the elderly. Several lines of evidence indicate that intrinsic defects preferentially affecting the naïve subset of CD4+T cells contribute to this reduced IL-2 production. Comparison of the biochemical pathways that transduce activation signals from the T cell receptor to the IL-2 promoter in young and old CD4+T cells has demonstrated age-related impairments at initial molecular events, in particular the phosphorylation of kinases and adapter proteins involved in the formation of signalosomes - complex multiprotein assemblies that provide the framework for effective signal transduction. Confocal microscopy has demonstrated a series of age-related impairments in effective immune synapse formation. Vitamin E can reverse many of these CD4+T cell age-associated defects, including reduced levels of phosphorylation of critical signaling/adapter proteins as well as defective immune synapse formation. Vitamin E also enhances IL-2 production, expression of several cell cycle control proteins, and proliferation. Although the precise mechanisms underlying this effect are not understood, it is possible that this antioxidant lipophilic vitamin can prevent the propagation of polyunsaturated fatty acid peroxidation in the cell membrane, influence the biochemical characteristics of specific lipid bilayer microdomains involved in signal transduction, modulate the activity of kinases/phosphatases, or interact with intracellular receptors.

Vitamin E and immunity

Vitamin E is the most important chain-breaking, lipid-soluble antioxidant present in body tissues of all cells and is considered the first line of defense against lipid peroxidation and it is important for normal function of the immune cells. However, vitamin E deficiency is rare in well-nourished healthy subjects and is not a problem, even among people living on relatively poor diets, both T- and B-cell functions are impaired by vitamin E deficiency. While immune cells are particularly enriched in vitamin E because of their high polyunsaturated fatty acid content, this point puts them at especially high risk for oxidative damage. Besides its immunomodulatory effects, vitamin E also plays an important role in carcinogenesis with its antioxidant properties against cancer, and ischemic heart disease with limiting the progression of atherosclerosis. Supplementation of vitamin E significantly enhances both cell mediated and humoral immune functions in humans, especially in the elderly and animals.

Preferential enhancement of older human T cell cytokine generation, chemotaxis, proliferation and survival by lenalidomide

Lenalidomide, an analog of thalidomide, modified responses of stimulated T cells from healthy young (ages 21-40 years) and old (≥ age 65 years) subjects. At 0.03 μM to 1 μM, lenalidomide enhanced generation of IL-2 and IFN-γ by T cell receptor-stimulated T cells of young subjects up to respective maximum increases of 17-fold and three-fold, but at 0.3 μM and 1 μM suppressed IL-17 generation. The same concentrations of lenalidomide enhanced IL-2 and IFN-γ generation by stimulated T cells of old subjects more, with greater respective maximal increases of up to 120-fold and six-fold, without suppressing IL-17 generation. Lenalidomide enhanced proliferation and suppressed apoptosis of stimulated T cells from old subjects, by IL-2-dependent mechanisms, and restored diminished T cell chemotactic responses to CCL21 and sphingosine 1-phosphate. The reversal of T cell abnormalities of immunosenescence by low concentrations of lenalidomide suggest a potential for improvement of immunity in the elderly.

Vitamin E transport, membrane incorporation and cell metabolism: Is alpha-tocopherol in lipid rafts an oar in the lifeboat?

Vitamin E is composed of closely related compounds, including tocopherols and tocotrienols. Studies of the last decade provide strong support for a specific role of alpha-tocopherol in cell signalling and the regulation of gene expression. It produces significant effects on inflammation, cell proliferation and apoptosis that are not shared by other vitamin E isomers with similar antioxidant properties. The different behaviours of vitamin E isomers might relate, at least in part, to the specific effects they exert at the plasma membrane. alpha-Tocopherol is not randomly distributed throughout the phospholipid bilayer of biological membranes, and as compared with other isomers, it shows a propensity to associate with lipid rafts. Distinct aspects of vitamin E transport and metabolism is discussed with emphasis on the interaction between alpha-tocopherol and lipid rafts and the consequences of these interactions on cell metabolism.

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.

Factors that may impact on immunosenescence: an appraisal

The increasing ratio of ageing population poses new challenges to healthcare systems. The elderly frequently suffer from severe infections. Vaccination could protect them against several infectious diseases, but it can be effective only if cells that are capable of responding are still present in the repertoire. Recent vaccination strategies in the elderly might achieve low effectiveness due to age-related immune impairment. Immunosenescence affects both the innate and adaptive immunity.Beside individual variations of genetic predisposition, epigenetic changes over the full course of human life exert immunomodulating effects. Disturbances in macrophage-derived cytokine release and reduction of the natural killer cell mediated cytotoxicity lead to increased frequency of infections. Ageing dampens the ability of B cells to produce antibodies against novel antigens. Exhausted memory B lymphocyte subsets replace naïve cells. Decline of cell-mediated immunity is the consequence of multiple changes, including thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, and deficiencies in cytokines production. Persistent viral and parasitic infections contribute to the loss of immunosurveillance and premature exhaustion of T cells. Reduced telomerase activity and Toll-like receptor expression can be improved by chemotherapy. Reversion of thymic atrophy could be achieved by thymus transplantation, depletion of accumulated dysfunctional naive T cells and herpesvirus-specific exhausted memory cells. Administration of interleukin (IL)-2, IL-7, IL-10, keratinocyte growth factor, thymic stromal lymphopoietin, as well as leptin and growth hormone boost thymopoiesis. In animals, several strategies have been explored to produce superior vaccines. Among them, virosomal vaccines containing polypeptide antigens or DNA plasmids as well as new adjuvanted vaccine formulations elicit higher dendritic cell activity and more effective serologic than conventional vaccines responses in the elderly. Hopefully, at least some of these approaches can be translated to human medicine in a not too far future.

The effects of vitamin E on NK cell activity and lymphocyte proliferation in treated mice by 2,3,7,8-tetrachlorodibenzo-p-dioxin

The study was conducted to investigate the effects of vitamin E on NK cell activity and lymphocyte proliferation in tr eated female mice by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In chronic TCDD trial, 45 mice were divided into 5 groups, and the levels of TCDD and vitamin E were 0 and 0, 100 and 0, 100 and 20, 100 and 100, and 100 ng/kg/d and 500 mg/kg/d, respectively. In acute TCDD trial, 24 mice were divided into three groups, and the levels of TCDD and vitamin E were 0 and 0, 30 and 0, and 30 microg/kg and 100 mg/kg, respectively. The results showed chronic TCDD-treatment caused decrease tendencies of spleen NK cell activity and lymphocyte proliferation, and vitamin E 100mg/kg alleviated the decreases tendencies caused by chronic TCDD-treatment, and the lymphocyte proliferation in the group given vitamin E 100mg/kg was significantly higher than that of the chronic TCDD-treated group. Acute TCDD-treatment suppressed the NK cell activity and lymphocyte proliferation, and vitamin E 100mg/kg significantly alleviated the decrease caused by acute TCDD-treatment. These results suggested that TCDD resulted in immunotoxicity, and the toxicity of acute TCDD-treatment was severe compared with chronic TCDD, while vitamin E alleviated the immunotoxicity from TCDD.

Immunosenescence and vaccination of the elderly II. New strategies to restore age-related immune impairment

One of the greatest health-care challenges in the elderly is to ensure that vaccination against infections are optimally effective, but vaccination can only be effective if cells that are capable of responding are still present in the repertoire. The reversing of immunosenescence could be achieved by improving immune responses or altering vaccine formulation. Recent vaccination strategies in the elderly exert low effectiveness. Nutritional interventions and moderate exercise delay T cell senescence. Telomerase activity and expression of toll-like receptors can be improved by chemotherapy. Reversion of thymic atrophy could be achieved by thymus transplantation, depletion of accumulated dysfunctional naive T cells and herpesvirus-specific exhausted memory cells. Administration of immunostimulatory and anti-inflammatory cytokines show the best practical approach. Reduced dendritic cell activity and co-receptor expression might be increased by interleukin (IL)-2 administration. IL-7 protects both B and T lymphocytes, but IL-2, IL-10, keratinocyte growth factor, thymic stromal lymphopoietin, as well as leptin and growth hormone also have a stimulatory effect on thymopoiesis. In animals, several strategies have been explored to produce more efficacious vaccines including high dose vaccines, DNA vaccines with immunostimulatory patch, virosomal vaccines and vaccines containing new adjuvants. Hopefully, one of these approaches will be translated into human therapy in a short time.

Naive CD4 T cells from aged mice show enhanced death upon primary activation

Poor T cell immunity is one of the many defects seen in elderly humans and aged (Ad) mice. We report that naive CD4 T cells from aged mice (ANCD4 cells) showed greater apoptosis upon primary activation than those from young (Yg) mice, with loss of mitochondrial membrane potential, poor activation of Rel family transcription factors and increased DNA damage. Their ability to enhance glycolysis, produce lactate and induce autophagy following activation was also compromised. ANCD4 cells remained susceptible to death beyond first cell division. Activated ANCD4 cells also showed poor transition to a 'central memory' (CM) CD44(high), CD62L(high) phenotype in vitro. This correlated with low proportions of CM cells in Ad mice in vivo. Functionally, too, IFN-gamma responses recalled from T cells of immunized Ad mice, poor to begin with, worsened with time as compared with Yg mice. Thus, ANCD4 cells handle activation-associated stress very poorly due to multiple defects, possibly contributing to poor formation of long-lasting memory.

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.

The dendritic and T cell responses to herpes simplex virus-1 are modulated by dietary vitamin E

Previous studies from our laboratory have shown that dietary alpha-tocopherol (vitamin E, or VE) is essential for regulating the cytokine and chemokine response in the brain to herpes simplex virus-1 (HSV-1) infection. The timing of T cell infiltration is critical to the resolution of central nervous system HSV-1 infections. Specifically, the appearance of "neuroprotective" CD8(+)IFN-gamma(+) T cells is crucial. During CNS infection, CD8(+) T cell priming and expansion in the draining lymph node, followed by recruitment and expansion, occurs in the spleen with subsequent accumulation in the brain. Weanling male BALB/cByJ mice were placed on VE-deficient (Def) or -adequate diets for 4 weeks followed by intranasal infection with HSV-1. VE-Def mice had fewer CD8(+)IFN-gamma(+) T cells trafficking to the brain despite increased CD8(+)IFN-gamma(+) T cells and activated dendritic cells in the periphery. VE-Def mice had increased T regulatory cells (Tregs) in the periphery and brain, and the increase in Tregs decreased CD8(+) T cell numbers in the brain. Our results demonstrate that adequate levels of VE are important for trafficking antigen-specific T cells to the brain, and dietary VE levels modulate T regulatory and dendritic cells in the periphery.

Vitamin E reverses impaired linker for activation of T cells activation in T cells from aged C57BL/6 mice

Supplemental vitamin E alleviates age-related defects in interleukin (IL)-2 production, T cell proliferation, and immune synapse formation. Here, we evaluated the effect of in vitro supplementation with 46 mumol/L of vitamin E on T cell receptor-proximal signaling events of CD4(+) T cells from young (4-6 mo) and old (22-26 mo) C57BL mice. Aged murine CD4(+) T cells stimulated via CD3 and CD28, tyrosine 191 of the adaptor protein Linker for Activation of T cells (LAT), was hypo-phosphorylated. Supplementation with vitamin E eliminated this difference in the tyrosine phosphorylation of LAT. By using a flow cytometric assay, the age-related differences in the activation-induced phosphorylation of LAT were observed in both naïve and memory T cell subsets. In addition, supplementation with vitamin E eliminates the age-related differences in LAT phosphorylation in both T cell subsets. Neither age nor vitamin E supplementation altered the fraction of LAT entering the membrane compartment. Furthermore, neither age nor vitamin E influenced the phosphorylation of Lck and Zap70, indicating that associated changes in LAT phosphorylation were not caused by alterations in activation states of the upstream kinases Lck and Zap70.

Nanonized black soybean enhances immune response in senescence-accelerated mice

Soy isoflavones may have applications in cancer prevention and anti-inflammation, therefore this study was conducted to investigate the effect of dietary supplementation with black soybean on the immune response in the senescence-accelerated-prone mice (SAMP8) and -resistant mice (SAMPR1, as controls). The mechanism of isoflavones was also investigated. Six-month-old male SAMP8 and SAMR1 mice were divided into the control groups and experimental groups supplemented with nanonized (Nano-soy) or microparticled (Micro-soy) black soybeans (n = 8/group), respectively for 12 weeks. Human peripheral blood mononuclear cells (PBMC) and murine splenocytes were stimulated with mitogens and cytokines were determined by reverse transcriptase-polymerase chain reaction and/or ELISA. The results showed that body weight, food intake, and relative weights of organs did not differ among the SAMP8 control and experimental groups. Isoflavone (daidzin and genistin) intake was higher in the Nano-soy group than the Micro-soy group. The lymphoproliferation and production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) in the Nano-soy group had a significantly higher (P < 0.05) than those in the control and Micro-soy groups. The Nano-soy supplemented mice reached these cytokine levels similar to SAMR1 mice. This result was consistent with the in vitro data that daidzein (a metabolite of daidzin), at a concentration of 10 muM, increased IL-2, IL-4, and IFN-gamma production from phytohemagglutinin-stimulated PBMC (P < 0.05). However at higher concentrations (> 50 microM), daidzein only reduced IL-10 and IFN-gamma levels, whereas genistein reduced levels of the IL-2, IL-4, IL-10, IFN-gamma mRNA and protein and these results suggest that the Nano-soy supplementation improved immune response in SAMP8 mice which may be attributable to higher daidzin content in the black soybean preparation.

Age-dependent signature of metallothionein expression in primary CD4 T cell responses is due to sustained zinc signaling

The ability to mount adaptive immune responses to vaccinations and viral infections declines with increasing age. To identify mechanisms leading to immunosenescence, primary CD4 T cell responses were examined in 60- to 75-year-old individuals lacking overt functional defects. Transcriptome analysis indicated a selective defect in zinc homeostasis. CD4 T cell activation was associated with zinc influx via the zinc transporter Zip6, leading to increased free cytoplasmic zinc and activation of negative feedback loops, including the induction of zinc-binding metallothioneins. In young adults, activation-induced cytoplasmic zinc concentrations declined after 2 days to below prestimulation levels. In contrast, activated naïve CD4 T cells from older individuals failed to downregulate cytoplasmic zinc, resulting in excessive induction of metallothioneins. Activation-induced metallothioneins regulated the redox state in activated T cells and accounted for an increased proliferation of old CD4 T cells, suggesting that regulation of T cell zinc homeostasis functions as a compensatory mechanism to preserve the replicative potential of naïve CD4 T cells with age.

Vitamin E: the shrew waiting to be tamed

Vitamin E is the last of all vitamins whose essentiality is not yet understood. Its widely accepted role as a lipophilic antioxidant has been questioned, since proof of its in vivo relevance remained scarce. The influence of vitamin E on biomarkers of oxidative stress in vivo is inconsistent and metabolites of vitamin E having reacted as an antioxidant are hardly detectable. Novel functions of vitamin E include the regulation of enzymes, most of which are membrane bound or activated by membrane recruitment. Also, expression of genes responds to vitamin E. The search for a transcription factor common to all regulated genes failed so far and a receptor that specifically binds vitamin E has not yet been identified. According to microarray data, pathways preferentially affected by the vitamin E status are the inflammatory response and cellular traffic. A role of vitamin E in cellular trafficking could best explain the neurological symptoms seen in vitamin E deficiency. Emerging knowledge on vitamin E is compiled here with the perspective to unravel the molecular mechanisms that could more likely explain the essentiality of the vitamin than its ability to scavenge free radicals.

Assessment of Age-related Decline of Immunological Function and Possible Methods for Immunological Restoration in Elderly

The immune system plays an important role in protection against infection and in the maintenance of the internal environment of the body. However, such important immune functions are known to decline with age in many mammals, including humans. It is a matter of clinical importance that the incidence of various age-associated diseases such as infections, cancer and vascular disorders increases with a decrease in immunological vigor. The extent of immunologic decline is variable and exhibits wide inter-individual variations. Thus, it is important to assess the extent of immunologic decline in both patients suffering from various diseases and in healthy people in order to maintain healthy conditions. To this end, we have developed a scoring system that analyzes immune parameters according to a database of known age-associated immune changes obtained from a healthy population. Using this scoring system, we can combine several different immunological parameters and express the immune status of individuals as a simple numeral.

After determining immunological vigor for individuals, it is necessary to replenish immune defects and restore them to normalcy for individuals with depressed immunological scores. This chapter provides methods of immunological restoration in animal models and introduces some similar attempts in humans. The effect of any immunological restoration varies with the individual and must therefore verified. Currently, the proposed immune scoring system proposed is useful to determine whether the methods employed are effective for the restoration of immune functions.

Immunity, ageing and cancer

Compromised immunity contributes to the decreased ability of the elderly to control infectious disease and to their generally poor response to vaccination. It is controversial as to how far this phenomenon contributes to the well-known age-associated increase in the occurrence of many cancers in the elderly. However, should the immune system be important in controlling cancer, for which there is a great deal of evidence, it is logical to propose that dysfunctional immunity in the elderly would contribute to compromised immunosurveillance and increased cancer occurrence. The chronological age at which immunosenescence becomes clinically important is known to be influenced by many factors, including the pathogen load to which individuals are exposed throughout life. It is proposed here that the cancer antigen load may have a similar effect on "immune exhaustion" and that pathogen load and tumor load may act additively to accelerate immunosenescence. Understanding how and why immune responsiveness changes in humans as they age is essential for developing strategies to prevent or restore dysregulated immunity and assure healthy longevity, clearly possible only if cancer is avoided. Here, we provide an overview of the impact of age on human immune competence, emphasizing T-cell-dependent adaptive immunity, which is the most sensitive to ageing. This knowledge will pave the way for rational interventions to maintain or restore appropriate immune function not only in the elderly but also in the cancer patient.

Vitamin E ingestion improves several immune functions in elderly men and women

The effects of diet supplementation with the antioxidant vitamin E (200 mg daily) on several blood neutrophil, lymphocyte and natural killer cell functions have been investigated in healthy elderly men and women before supplementation, after 3 months of supplementation and 6 months after the end of supplementation (post-supplementation). In parallel, samples of healthy adult men and women were used as age controls. In elderly men and women, an impairment of immune functions was observed in comparison with the respective adult controls and the intake of vitamin E resulted in a significant enhancement of immune parameters in both elderly men and women, bringing their values close to those in the adults. These effects were not found in post-supplementation samples in several but not in all functions. The present findings suggest that supplementation with vitamin E can produce an improvement of immune functions and therefore of health in aged people.

Age-associated changes in immune and inflammatory responses: impact of vitamin E intervention

Aging is associated with dysregulated immune and inflammatory responses. Declining T cell function is the most significant and best-characterized feature of immunosenescence. Intrinsic changes within T cells and extrinsic factors contribute to the age-associated decline in T cell function. T cell defect seen in aging involves multiple stages from early receptor activation events to clonal expansion. Among extrinsic factors, increased production of T cell-suppressive factor PGE(2) by macrophages (Mphi) is most recognized. Vitamin E reverses an age-associated defect in T cells, particularly naïve T cells. This effect of vitamin E is also reflected in a reduced rate of upper respiratory tract infection in the elderly and enhanced clearance of influenza infection in a rodent model. The T cell-enhancing effect of vitamin E is accomplished via its direct effect on T cells and indirectly by inhibiting PGE(2) production in Mphi. Up-regulated inflammation with aging has attracted increasing attention as a result of its implications in the pathogenesis of diseases. Increased PGE(2) production in old Mphi is a result of increased cyclooxygenase 2 (COX-2) expression, leading to higher COX enzyme activity, which in turn, is associated with the ceramide-induced up-regulation of NF-kappaB. Similar to Mphi, adipocytes from old mice have a higher expression of COX-2 as well as inflammatory cytokines IL-1beta, IL-6, and TNF-alpha, which might also be related to elevated levels of ceramide and NF-kappaB activation. This review will discuss the above age-related immune and inflammatory changes and the effect of vitamin E as nutritional intervention with a focus on the work conducted in our laboratory.

Effect of exogenous vitamin E on proliferation and cytokine production in peripheral blood mononuclear cells from patients with tuberculosis

Micronutrient deficiencies are frequently associated with tuberculosis (TB) worldwide. We tested the effect of exogenous vitamin E on proliferation and cytokine production of peripheral blood mononuclear cells (PBMC) from TB patients and healthy purified protein derivative (PPD)+ volunteers. Proliferation was stimulated with mycobacterial antigen (PPD) and evaluated by the incorporation of tritiated thymidine in PBMC cultured with or without 50 microm-vitamin E for 6 d. Cytokine production (IL-2 and interferon (IFN)-gamma) was determined by intracellular cytokine staining and by ELISA in the supernatant of PBMC stimulated for 24 h with phytohaemagglutinin or PPD. Our results show that culture with vitamin E increased (P < or = 0.05 ) the antigen-induced proliferation of PBMC in TB patients but not in healthy PPD+ volunteers. No significant changes in the number of cytokine-producing cells or in the production of IFN-gamma were observed with vitamin E treatment. These results indicate that vitamin E may enhance the antigen-specific in vitro response of PBMC from TB patients.

Nuclear factor-kappaB-dependent reversal of aging-induced alterations in T cell cytokines

Immunosenescence is characterized by decreases in protective immune responses and increases in inflammation and autoimmunity. The T helper (Th)17 subset of cluster-of-differentiation (CD)4 T cells, which is identified by its generation of interleukin (IL) -17, is implicated in autoimmune pathogenesis. To elucidate immunosenescent changes in Th17 cell cytokines, splenic CD4 T cells from 22- to 24-month-old (old) mice and 6- to 10-wk-old (young) mice were incubated on anti-CD3 plus anti-CD28 (anti-T cell antigen receptor) antibodies. After 96 h, T cells of old C57BL/6 and CBA mice generated up to 20-fold more IL-17 and up to 3-fold more IL-6 than those of young mice; T cells of young mice generated up to 5-fold more IL-21 than those of old mice; and no difference was found for IFN-gamma. At 24 h, cytokine mRNA levels paralleled 96 h cytokine concentrations. Naive CD4 T cells from old mice incubated on anti-T cell antigen receptor antibodies with transforming growth factor-beta, IL-1, IL-6, and IL-23 to induce de novo differentiation of Th17 cells had more IL-17 mRNA and produced more IL-17 than those of young mice. BAY11-7082 and the phytochemicals triptolide and butein suppressed nuclear concentrations of nuclear factor-kappaB and secreted levels of IL-17, IL-21, and IFN-gamma in parallel, with greater potency in Th17 cells from young than old mice. Pharmacological correction of altered generation of Th17 cell cytokines in immunosenescence represents a novel therapeutic approach to aging-induced inflammatory diseases.

The immune response to herpes simplex virus encephalitis in mice is modulated by dietary vitamin E

Herpes simplex virus encephalitis (HSE) is the most common fatal sporadic encephalitis in humans. HSE is primarily caused by herpes simplex virus (HSV)-1 infection of the brain. HSE results in increased levels of oxidative stress, including the production of reactive oxygen species, free radicals, and neuroinflammation. The most biologically active form of vitamin E (VE) is alpha-tocopherol (alpha-TOC). In cellular membranes, alpha-TOC prevents lipid peroxidation by scavenging free radicals and functioning as an antioxidant. Supplementation with VE has been shown to decrease immunosenescence, improve immune function, and may be neuroprotective. To determine how VE deficiency and VE supplementation would alter the pathogenesis of HSE, we placed weanling male BALB/cByJ mice on VE-deficient (VE-D), VE-adequate (VE-A), or 10x VE-supplemented diets for 4 wk, and then infected the mice intranasally with HSV-1. VE-D mice had more severe symptoms of encephalitis than VE-A mice, including weight loss, keratitis, hunched posture, and morbidity. VE-D mice had increased cytokine and chemokine expression in the brain and increased viral titers. In contrast, VE supplementation failed to decrease cytokine production and had no effect on viral titer. We demonstrated that adequate levels of VE are important in limiting HSE pathology and that 10x supplementation does not enhance protection.

Combination of physical activity, nutrition, or other metabolic factors and vaccine response

A number of lifestyle factors that reduce cancer risk in the primary prevention setting may be potential new targets for use in combination with cancer vaccines. This review discusses the modulation of energy balance (physical activity, calorie restriction, and obesity prevention), and the supplementation with natural and synthetic analogs of vitamins A and E, as potential interventions for use in combination with cancer vaccines. Additionally, the pharmacologic manipulation of nutrient metabolism in the tumor microenvironment (e.g., arachidonic acid, arginine, tryptophan, and glucose metabolism) is discussed. This review includes a brief overview of the role of each agent in primary cancer prevention; outlines the effects of these agents on immune function, specifically adaptive and/or anti-tumor immune mechanisms, when known; and discusses the potential use of these interventions in combination with therapeutic cancer vaccines. Modulation of energy balance through exercise and strategies targeting nutrient metabolism in the tumor microenvironment represent the most promising interventions to partner with therapeutic cancer vaccines. Additionally, the use of vitamin E succinate and the retinoid X receptor-directed rexinoids in combination with cancer vaccines offer promise. In summary, a number of energy balance- and nutrition-related interventions are viable candidates for further study in combination with cancer vaccines.

Genome-wide screening of alpha-tocopherol sensitive genes in heart tissue from alpha-tocopherol transfer protein null mice (ATTP(-/-))

Alpha-tocopherol transfer protein (ATTP) null mice (ATTP(-/-)) have a systemic deficiency of alpha-tocopherol (AT). The heart AT levels of ATTP(-/-) are <10% of those in ATTP(+/+) mice. The genomic responses of heart to AT deficiency were determined in 3 months old male ATTP(-/-) mice and compared with their ATTP(+/+) littermate controls using Affymetrix 430A 2.0 high density oligonucleotide arrays. Differential analysis of approximately 13000 genes identified repression of genes related to immune system and activation of genes related to lipid metabolism and inflammation with no significant change in the expression of classical antioxidant genes (catalase, superoxide dismutase, glutathione peroxidase) in ATTP(-/-) as compared to ATTP(+/+) mice. The present data identifies novel classes of AT sensitive genes in heart tissue.