Jolanta Jajte

Effect of zinc supplementation on plasma IL-6 and MCP-1 production and NK cell function in healthy elderly: Interactive influence of +647 MT1a and −174 IL-6 polymorphic alleles

Pro-inflammatory cytokine response and NK activity are controlled by the availability of zinc ion, whose intra-cellular transport is regulated by metallothioneins. In order to closely examine the importance of circulating zinc in the modulation of immune response during ageing, in the balance of Th2/Th1 equilibrium and finally in the reversibility of systemic low grade inflammation, we evaluated the changes occurring in plasma IL-6 and MCP-1 concentrations and NK lytic activity in a healthy low grade inflamed elderly population, following zinc-aspartate supplementation. In addition, we aimed to highlight the potential interaction among circulating zinc increments, changes in immunological parameters and +647 MT1a and -174 IL-6 polymorphic alleles. Thirty-nine healthy individuals (60-83 years) from the ZINCAGE cohort (previously typed for +647 MT1a and -174 IL-6 polymorphisms) were supplied with zinc-aspartate. Blood samples collected before and after supplementation underwent basal laboratory determinations (circulating zinc, albumin and C-reactive protein) and immunological studies (plasma IL-6 and MCP-1 and NK lytic activity). Zinc supplementation in subjects with low or borderline-normal circulating zinc increased the concentration of this ion and modulated plasmatic IL-6 and MCP-1 as well as NK lytic activity. An interactive effect of polymorphic alleles of MT1a and IL-6 genes on zinc, IL-6, MCP-1 and NK activity was evidenced following supplementation, indicating the genetic background as one of the determinants for identifying groups of subjects that can take advantage of therapeutic intervention.

TH1 and TH2 cell polarization increases with aging and is modulated by zinc supplementation.

Elderly subjects suffer from increased levels of activated T cells and a TH1/TH2 imbalance. Zinc deficiency of the aged is correlated with decreased cell-mediated immune responses. The association of age and zinc adjustment with the amounts of TH1 (CCR5+) and TH2 (CCR4+) cell populations in healthy aged old donors enrolled in the European ZINCAGE project was examined. Old and nonagenarian individuals revealed increased TH1, TH2 cell numbers and a decreased TH2/TH1 ratio in comparison to young individuals. The differences between TH2/TH1 ratios of young and old/nonagenarians arose from young females. Adjusted zinc status led to enhanced TH2 and TH1 amounts in fresh whole blood and thawed cells of aged donors whereas increased HLA-DR+ expression and a generally lower CCR5 expression was observed on thawed PBMC. In conclusion, aging is associated with an increase in T helper cell polarization, and changes in TH2/TH1 subsets are more obvious in women than in men. Advanced healthy aging is accompanied by TH cell polarization, too. Moderate zinc supplementation in vivo alters TH proportions. Longer zinc treatment will give more insight into the beneficial effect of zinc on T helper cell modulation.

Zinc, metallothioneins, and longevity--effect of zinc supplementation: zincage study.

Abstract:  Aging is an inevitable biological process that is associated with gradual and spontaneous biochemical and physiological changes and increased susceptibility to diseases. Because nutritional factors are involved in improving immune functions, metabolic harmony, and antioxidant defense, some nutritional factors, such as zinc, may modify susceptibility to disease and promote healthy aging. In vitro (human lymphocytes exposed to endotoxins) and in vivo (old or young mice fed with low zinc dietary intake) studies revealed that zinc is important for immune efficiency (innate and adaptive), antioxidant activity (supeoxide dismutase), and cell differentiation via clusterin/apolipoprotein J. Intracellular zinc homeostasis is regulated by metallothioneins (MT) via ion release through the reduction of thiol groups in the MT molecule. This process is crucial in aging because high MT levels are not able to release zinc, resulting in low intracellular free ion availability for biological functions. Improvement in these functions occurs in the elderly after physiological zinc supplementation. In this study, the selection of elderly subjects for zinc supplementation is discussed in relation to the genetic background of MT and pro‐inflammatory cytokines, such as interleukin‐6, because the latter is involved both in MT‐gene expression and in intracellular zinc homeostasis.

Effects of zinc supplementation on antioxidant enzyme activities in healthy old subjects

A large body of experimental research indicates that oxidative stress contributes to the processes related to aging and age-related diseases. Trace elements, particularly zinc (Zn), are essential components of the endogenous enzymatic antioxidant defenses. The aim of this study was to determine the activity of three main antioxidant enzymes in plasma [i.e. superoxide dismutase (pSOD), catalase (CAT), glutathione peroxidase (GPx)] and of SOD in erythrocyte (eSOD) in a group of 1108 healthy elderly subjects from different European countries. The same enzymatic activities were evaluated in a subgroup of 108 subjects before and after Zn supplementation. We observed that eSOD activity increased with age, whereas plasma Zn decreased. Moreover, we found that women showed higher eSOD activity and lower plasma Zn compared to men. There were no age and gender-related differences in the activities of pSOD, CAT and GPx. After Zn supplementation, the activities of Zn-dependent enzymes (pSOD and eSOD), as well as plasma Zn concentration, were significantly higher than before supplementation. These results were not influenced by age, gender, plasma Zn variations (Delta Zn) and geographic area. These data suggest the potential beneficial effects of Zn supplementation on Zn-dependent antioxidant enzymes in healthy elderly subjects.

Zinc salts differentially modulate DNA damage in normal and cancer cells

Zinc plays an essential role in a wide range of cellular processes, including defense against free radicals and maintaining genomic stability. The presence of zinc in some proteins is fundamental for their functioning as transcription factors. Little is known about interaction between zinc and DNA, which can be important in light of reports on the role of zinc in cancer transformation and sometimes contradictory character of these reports. In the present study we studied cyto‐ and genotoxicity of zinc sulfate (ZnSO4) in normal human lymphocytes and human myelogenous lukemia K562 cancer cells in the presence of zinc and hydrogen peroxide (H2O2). Zinc at concentrations from the range 10–1000 μM decreased the viability of cancer cells and this effect, especially for low concentrations of the element, was much more pronounced than in normal cells. Zinc did not induce DNA damage in normal cells, but did so in cancer cells. We observed a key difference between the action of zinc in normal and cancer cells in the presence of H2O2, since the element exerted a protective effect against cyto‐ and geno‐toxic action of H2O2 in the former, whereas it increased such action in the latter. Zinc inhibited the repair of DNA damage induced by H2O2 in cancer cells. The results suggest that zinc may protect normal cells against DNA‐damaging action and increase this action in cancer cells, which indicates the dual action of this element in dependency of target cells and can be useful in cancer therapy.

Effect of zinc on cellular poly(ADP-ribosyl)ation capacity

Poly(ADP-ribosyl)ation is a posttranslational protein modification, which is catalyzed by poly(ADP-ribose) polymerase-1 (PARP-1) and plays a role in DNA repair and maintenance of genomic stability. A decrease in cellular poly(ADP-ribosyl)ation has been implicated in the aging process. As PARP-1 is a zinc finger protein its decreased function might be related to age-related zinc deficiency. To test this hypothesis we assessed cellular poly(ADP-ribosyl)ation capacity in 29 donors from Greece, Italy and Poland as function of age and nutritional zinc status. Our results reveal a positive correlation between cellular poly(ADP-ribosyl)ation capacity and zinc status in human peripheral blood mononuclear cells (PBMC) (p<0.05). We could also confirm a decrease of PARP-1 activity with donor age, highlighting the role of poly(ADP-ribosyl)ation in the aging process. The results demonstrate that zinc supplementation in elderly people can increase the cellular poly(ADP-ribosyl)ation capacity of their PBMC. We speculate that this may help maintain integrity and stability of the genome more efficiently and thus contribute to an extension of healthspan.

Mediterranean diet and plasma concentration of inflammatory markers in old and very old subjects in the ZINCAGE population study.

Abstract Background: Aging is associated with low-grade elevation of circulating inflammatory markers, leading to increased risk of morbidity and mortality. The Mediterranean diet has been suggested as a determinant of longevity. In the current study, we investigated the impact of the Mediterranean diet on inflammatory status in old subjects. Methods: Within the ZINCAGE study, 957 healthy old subjects (≥60 years old) from five European countries were recruited. Plasma interleukin (IL)-6, IL-8, monocyte chemoattractant protein, tumor necrosis factor-α, high-density lipoprotein cholesterol (HDL-C) and erythrocyte sedimentation rate (ESR) were measured. Dietary data were collected applying a food frequency questionnaire and were used to estimate adherence to the Mediterranean diet. Results: The Italians presented the greatest adherence to the Mediterranean diet, while the Polish the poorest. In females, higher diet score was significantly associated with lower body mass index and ESR and higher HDL-C levels (β=−0.127, p=0.003; β=−0.144, p=0.001; β=0.144, p=0.029, respectively). In males, diet score was negatively associated with IL-8 levels (β=−0.101, p=0.044). The Mediterranean diet was associated with reduced IL-8 concentrations in Greeks (β=−0.213, p=0.007). Conclusions: There were significant effects of the components of the Mediterranean diet on inflammation markers. The Mediterranean diet score is useful in assessing nutritional influence on immune status. Clin Chem Lab Med 2008;46:990–6.

Assessment of gene-nutrient interactions on inflammatory status of the elderly with the use of a zinc diet score - ZINCAGE study.

Although zinc plays an important role in health status of the elderly, their dietary habits in relation to zinc intake are not well documented. The main objective of the current study was the assessment of dietary zinc intake in European old populations and the investigation of its impact on plasma zinc and inflammatory cytokines concentrations, in relation to genetic markers. Within the ZINCAGE study, 819 healthy old Europeans (>or=60 years old) were recruited. Plasma zinc, interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured. Genotype data were obtained for the -174G/C polymorphism in the IL-6 gene. Dietary data were collected with a food frequency questionnaire and were used to calculate a zinc diet score. Zinc score was validated using additional dietary data (24-h recalls), in a subsample of 105 subjects. Zinc score was different among most of the European centres (P<.001), while an age-dependent decline was documented (P=4.4x10(-12)). Plasma zinc concentrations were significantly correlated with the zinc score (standardized beta=0.144, P=8.8x10(-5)). The minor allele frequency for the -174G/C polymorphism was f(C) 0.31. There was a significant interaction of zinc diet score and GG (-174G/C) genotype on higher plasma IL-6 levels (beta+/-S.E.=0.014+/-0.0, P=.008). The main finding of our study was the detection of gene-nutrient and biochemical-nutrient interactions in a multiethnic cohort based on a common dietary assessment tool.

DNA damage induced by nitrous oxide: study in medical personnel of operating rooms.

Occupational exposure to anaesthetics such as nitrous oxide (N(2)O) and halogenated hydrocarbons has been suggested to increase risk of genetic damage. However, the dose-dependency of genotoxic effects has not been unequivocally established and their relation to occupational exposure limit (OEL) remain obscure. In this study, the genotoxicity associated with occupational exposure to anaesthetics has been investigated in a group of 55 female nurses and 29 male anaesthesiologists active for at least 5 years in a working environment containing variable concentrations of N(2)O and halogenated hydrocarbons. 83 unexposed health care workers (52 female nurses and 31 male doctors) matched for age, gender, smoking habit and employment duration were included in the control group. Genotoxicity has been assessed using comet test. Concentrations of nitrous oxide, sevoflurane and isoflurane monitored by gas chromatography and mass spectrometry made possible to relate the extent of DNA damage to the level of exposure. Our results for the first time document a positive correlation between the DNA damage and the N(2)O levels in the ambient air. By contrast, no correlation has been observed between genotoxic effects and concentrations of sevoflurane and isoflurane. The extent of genetic injury was especially aggravated among nurses and anaesthesiologists exposed to N(2)O in concentrations exceeding OEL (180 mg/m(3)). We conclude that occupational exposure to N(2)O is associated with increased DNA damage and that the level of exposure plays a critical role in this regard.

Metallothionein downregulation in very old age: a phenomenon associated with cellular senescence?

It is known that metallothionein (MT) mRNA expression first increases with age, but then decreases again in the very elderly. Here we report that MT protein levels also decrease in very old age, and that this is independent of dietary zinc intake. Age-related changes of MT, as well as alterations of zinc homeostasis (intracellular labile zinc and NO-induced zinc release), occur both in human PBMCs ex vivo and also in CD4+ T cell clones progressing through their finite life span in vitro. These results suggest that phenomena observed in very old people can be at least partially attributed to diminished cell proliferation.