The influence of selenium on immune responses.
ABSTRACT Selenium (Se) is a potent nutritional antioxidant that carries out biological effects through its incorporation into selenoproteins. Given the crucial roles that selenoproteins play in regulating reactive oxygen species (ROS) and redox status in nearly all tissues, it is not surprising that dietary Se strongly influences inflammation and immune responses. The notion that Se "boosts" the immune system has been supported by studies involving aging immunity or protection against certain pathogens. However, studies examining the effects of Se status on other types of immunity such as antiparasitic responses or allergic asthma have suggested more Se may not always be beneficial. In this review, we summarize and compare the available data regarding how the levels of Se affect different types of immunity. Overall, determining how Se intake differentially affects various types of immune responses and dissecting the mechanisms by which this occurs will lead to a better utilization of Se-supplementation for human diseases involving the immune system.
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ABSTRACT: This study was designed to determine the effect of selenium (Se) deficiency on the immune response to infection with a virulent strain of influenza virus, influenza A/Puerto Rico/8/34. Previous work in our laboratory demonstrated that Se-deficient mice infected with a mild strain of influenza virus, influenza A/ Bangkok/1/79, developed much more severe lung pathology compared with Se-adequate mice. Immune function was altered in the Se-deficient mice, and the viral genome changed to a more virulent genotype. In this study, we tested whether Se deficiency would have a similar effect on mice infected with a more virulent, mouse-adapted strain of influenza virus. Three-week-old male mice were fed Se-adequate or Se-deficient diet for 4 weeks before inoculation with influenza A/PR8/34. There was no difference in lung influenza viral titer between Se-deficient and Se-adequate mice. Se-deficient mice had less macrophage inflammatory protein 1alpha (MIP-1alpha) and regulated upon activation, normal T cell expressed and secreted (RANTES) production at the transcriptional and protein level in the lung postinfection. Se-deficient mice also had higher levels of IL-2 expression followed by a higher level of IL-4 expression in the lung. At Day 7 postinfection, there was no death in the Se-deficient group compared with 50% of the mice dying in the Se-adequate group. Sequencing of the virus isolated from infected Se-adequate and Se-deficient mice did not detect viral genome mutations in either group. This study demonstrated that Se-deficient mice had an altered immune response to an infection with a virulent strain of influenza virus. This altered immune response was beneficial for protecting the mice from influenza virus-induced mortality.Experimental Biology and Medicine 04/2007; 232(3):412-9. · 2.80 Impact Factor
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ABSTRACT: Aging is accompanied by chronic inflammation and oxidative stress, which lead to a marked impairment of immune function and therefore increased mortality. This study assessed the effect of dietary supplementation, for 15 wk, with 5% and 20% (w/w) of biscuits enriched with nutritional doses of vitamins C and E, zinc, selenium, and beta-carotenes on function and oxidative stress parameters of peritoneal leukocytes from middle-aged, prematurely aging mice (PAM) and non-prematurely aging mice (NPAM). After supplementation we measured leukocyte functions (adherence, chemotaxis, phagocytosis, intracellular reactive oxygen species levels, lymphoproliferation, natural killer activity, and interleukin-2 release), antioxidant defenses (superoxide dismutase, glutathione peroxidase, and reduced glutathione), oxidant compounds (extracellular O(2)(-), glutathione disulfide, glutathione disulfide/reduced glutathione ratio, tumor necrosis factor-alpha, nitric oxide, and prostaglandin E(2)), and lipid and DNA oxidative damage, measured by malondialdehyde and 8-oxo,7,8-dihydro-2'-deoxyguanosine levels, respectively. In general, leukocyte functions were improved and redox homeostasis was restored after intake of antioxidants. In consequence, malondialdehyde and 8-oxo,7,8-dihydro-2'-deoxyguanosine in PAM and NPAM were strikingly decreased after 5% and 20% supplementation (malondialdehyde, P < 0.001 in PAM; P < 0.01 in NPAM after both treatments; 8-oxo,7,8-dihydro-2'-deoxyguanosine, P < 0.01 after 5% supplementation and P < 0.001 after 20% supplementation in PAM and NPAM). Moreover, the effect of the antioxidants was stronger in PAM than in NPAM, and 20% supplementation was more effective than 5%. Our data suggest that improvement of leukocyte function and restoration of redox balance after consumption of adequate levels of antioxidants from adulthood may be useful to attain healthy aging, especially in animals with premature aging.Nutrition 01/2006; 22(7-8):767-77. · 2.86 Impact Factor
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ABSTRACT: Supplementation with 200 microg/day of sodium selenite during therapy for squamous cell carcinoma (SQCC) of the head and neck, e.g., surgery, radiation, or surgery and radiation, resulted in a significantly enhanced cell-mediated immune responsiveness. The enhanced responsiveness was evident during therapy and following conclusion of therapy. In contrast, patients in the placebo arm of the study showed a decline in immune responsiveness during therapy. The results from studies on mice inoculated with SQCC cells expressing the receptor for interleukin-2 (IL-2) and supplemented with Se (2.00 ppm) indicated that Se significantly retards the clinical appearance of tumors; peritumoral injections of 2,000 IU of IL-2 resulted in 50% reduction in the size of established tumors and 72% of early tumors. The combined data suggested that local immunotherapy with IL-2 in hosts supplemented with Se may represent an effective modality of treatment for the prevention of recurrences at the site of conventionally treated primary tumors.BioFactors 02/2001; 14(1-4):161-8. · 3.09 Impact Factor