T-lymphocyte subsets and interleukin-2 production in zinc-deficient rats

Interplay between zinc and cell proliferation and implications for the growth of livestock

Zinc (Zn) plays a critical role in the growth of livestock, which depends on cell proliferation. In addition to modifying the growth associated with its effects on food intake, mitogenic hormones, signal transduction and gene transcription, Zn also regulates body weight gain through mediating cell proliferation. Zn deficiency in animals leads to growth inhibition, along with an arrest of cell cycle progression at G0/G1 and S phase due to depression in the expression of cyclin D/E and DNA synthesis. Therefore, in the present study, the interplay between Zn and cell proliferation and implications for the growth of livestock were reviewed, in which Zn regulates cell proliferation in several ways, especially cell cycle progression at the G0/G1 phase DNA synthesis and mitosis. During the cell cycle, the Zn transporters and major Zn binding proteins such as metallothioneins are altered with the requirements of cellular Zn level and nuclear translocation of Zn. In addition, calcium signaling, MAPK pathway and PI3K/Akt cascades are also involved in the process of Zn-interfering cell proliferation. The evidence collected over the last decade highlights the necessity of Zn for normal cell proliferation, which suggests Zn supplementation should be considered for the growth and health of poultry.

Supplementation With Vitamin E, Zinc, Selenium, and Copper Re-Establishes T-Cell Function and Improves Motor Recovery in a Rat Model of Spinal Cord Injury

Spinal cord injury (SCI) causes a dysfunction of sympathetic nervous system innervation that affects the immune system, leading to immunosuppression syndrome (ISS) and contributing to patient degeneration and increased risk of several infections. A possible therapeutic strategy that could avoid further patient deterioration is the supplementation with Vitamin E or trace elements, such as Zinc, Selenium, and Copper, which individually promotes T-cell differentiation and proliferative responses. For this reason, the aim of the present study was to evaluate whether Vitamin E, Zinc, Selenium, and Copper supplementation preserves the number of T-lymphocytes and improves their proliferative function after traumatic SCI. Sprague–Dawley female rats were subjected to moderate SCI and then randomly allocated into three groups: (1) SCI + supplements; (2) SCI + vehicle (olive oil and phosphate-buffered saline); and (3) sham-operated rats. In all rats, the intervention was initiated 15 min after SCI and then administered daily until the end of study. Locomotor recovery was assessed at 7 and 15 days after SCI. At 15 days after supplementation, the quantification of the number of T-cells and its proliferation function were examined. Our results showed that the SCI + supplements group presented a significant improvement in motor recovery at 7 and 15 days after SCI. In addition, this group showed a better T-cell number and proliferation rate than that observed in the group with SCI + vehicle. Our findings suggest that Vitamin E, Zinc, Selenium, and Copper supplementation could be part of a therapy for patients suffering from acute SCI, helping to preserve T-cell function, avoiding complications, and promoting a better motor recovery. All procedures were approved by the Animal Bioethics and Welfare Committee (Approval No. 201870; CSNBTBIBAJ 090812960).

Medicinal Plants and Zinc: Impact on COVID-19 Pandemic

The world is currently grappling with the coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection can cause fever, a dry cough, fatigue, severe pneumonia, respiratory distress syndrome, and in some cases death. There is currently no effective antiviral SARS-CoV-2 drug. To reduce the number of infections and deaths, it is critical to focus on strengthening immunity. This review aims to conduct a comprehensive search on the previous studies using Google Scholar, ScienceDirect, Medline, PubMed, and Scopus for the collection of research papers based on the role of zinc in the immune system, the antiviral activity of zinc, the effect of zinc supplementation in respiratory infections, the therapeutic approaches against viral infections based on medicinal plants, and the role of plants' bioactive molecules in fighting viral infections. In conclusion, we highlighted the pivotal role of zinc in antiviral immunity and we suggested the bioactive molecules derived from medicinal plants as a search matrix for the development of anti-SARS-CoV-2 drugs.

Dietary and Physiological Effects of Zinc on the Immune System

Evidence for the importance of zinc for all immune cells and for mounting an efficient and balanced immune response to various environmental stressors has been accumulating in recent years. This article describes the role of zinc in fundamental biological processes and summarizes our current knowledge of zinc's effect on hematopoiesis, including differentiation into immune cell subtypes. In addition, the important role of zinc during activation and function of immune cells is detailed and associated with the specific immune responses to bacteria, parasites, and viruses. The association of zinc with autoimmune reactions and cancers as diseases with increased or decreased immune responses is also discussed. This article provides a broad overview of the manifold roles that zinc, or its deficiency, plays in physiology and during various diseases. Consequently, we discuss why zinc supplementation should be considered, especially for people at risk of deficiency. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Role of Divalent Cations in HIV-1 Replication and Pathogenicity

Divalent cations are essential for life and are fundamentally important coordinators of cellular metabolism, cell growth, host-pathogen interactions, and cell death. Specifically, for human immunodeficiency virus type-1 (HIV-1), divalent cations are required for interactions between viral and host factors that govern HIV-1 replication and pathogenicity. Homeostatic regulation of divalent cations' levels and actions appear to change as HIV-1 infection progresses and as changes occur between HIV-1 and the host. In people living with HIV-1, dietary supplementation with divalent cations may increase HIV-1 replication, whereas cation chelation may suppress HIV-1 replication and decrease disease progression. Here, we review literature on the roles of zinc (Zn2+), iron (Fe2+), manganese (Mn2+), magnesium (Mg2+), selenium (Se2+), and copper (Cu2+) in HIV-1 replication and pathogenicity, as well as evidence that divalent cation levels and actions may be targeted therapeutically in people living with HIV-1.

Metalloimmunology: The metal ion-controlled immunity

Metals are essential components in all forms of life required for the function of nearly half of all enzymes and are critically involved in virtually all fundamental biological processes. Especially, the transition metals iron (Fe), zinc (Zn), manganese (Mn), nickel (Ni), copper (Cu) and cobalt (Co) are crucial micronutrients known to play vital roles in metabolism as well due to their unique redox properties. Metals carry out three major functions within metalloproteins: to provide structural support, to serve as enzymatic cofactors, and to mediate electron transportation. Metal ions are also involved in the immune system from metal allergies to nutritional immunity. Within the past decade, much attention has been drawn to the roles of metal ions in the immune system, since increasing evidence has mounted to suggest that metals are critically implicated in regulating both the innate immune sensing of and the host defense against invading pathogens. The importance of ions in immunity is also evidenced by the identification of various immunodeficiencies in patients with mutations in ion channels and transporters. In addition, cancer immunotherapy has recently been conclusively demonstrated to be effective and important for future tumor treatment, although only a small percentage of cancer patients respond to immunotherapy because of inadequate immune activation. Importantly, metal ion-activated immunotherapy is becoming an effective and potential way in tumor therapy for better clinical application. Nevertheless, we are still in a primary stage of discovering the diverse immunological functions of ions and mechanistically understanding the roles of these ions in immune regulation. This review summarizes recent advances in the understanding of metal-controlled immunity. Particular emphasis is put on the mechanisms of innate immune stimulation and T cell activation by the essential metal ions like calcium (Ca²⁺), zinc (Zn²⁺), manganese (Mn²⁺), iron (Fe²⁺/Fe³⁺), and potassium (K⁺), followed by a few unessential metals, in order to draw a general diagram of metalloimmunology.

Function, Structure, and Transport Aspects of ZIP and ZnT Zinc Transporters in Immune Cells

Zinc is an important trace metal in immune systems, and zinc transporters are involved in many immune responses. Recent advances have revealed the structural and biochemical bases for zinc transport across the cell membrane, with clinical implications for the regulation of zinc homeostasis in immune cells like dendritic cells, T cells, B cells, and mast cells. In this review, we discuss the function, structure, and transport aspects of two major mammalian zinc transporter types, importers and exporters. First, Zrt-/Irt-like proteins (ZIPs) mediate the zinc influx from the extracellular or luminal side into the cytoplasm. There are 14 ZIP family members in humans. They form a homo- or heterodimer with 8 transmembrane domains and extra-/intracellular domains of various lengths. Several ZIP members show specific extracellular domains composed of two subdomains, a helix-rich domain and proline-alanine-leucine (PAL) motif-containing domain. Second, ZnT (zinc transporter) was initially identified in early studies of zinc biology; it mediates zinc efflux as a counterpart of ZIPs in zinc homeostasis. Ten family members have been identified. They show a unique architecture characterized by a Y-shaped conformation and a large cytoplasmic domain. A precise, comprehensive understanding of the structures and transport mechanisms of ZIP and ZnT in combination with mice experiments would provide promising drug targets as well as a basis for identifying other transporters with therapeutic potential.

Zinc and Skin Disorders

The skin is the third most zinc (Zn)-abundant tissue in the body. The skin consists of the epidermis, dermis, and subcutaneous tissue, and each fraction is composed of various types of cells. Firstly, we review the physiological functions of Zn and Zn transporters in these cells. Several human disorders accompanied with skin manifestations are caused by mutations or dysregulation in Zn transporters; acrodermatitis enteropathica (Zrt-, Irt-like protein (ZIP)4 in the intestinal epithelium and possibly epidermal basal keratinocytes), the spondylocheiro dysplastic form of Ehlers-Danlos syndrome (ZIP13 in the dermal fibroblasts), transient neonatal Zn deficiency (Zn transporter (ZnT)2 in the secretory vesicles of mammary glands), and epidermodysplasia verruciformis (ZnT1 in the epidermal keratinocytes). Additionally, acquired Zn deficiency is deeply involved in the development of some diseases related to nutritional deficiencies (acquired acrodermatitis enteropathica, necrolytic migratory erythema, pellagra, and biotin deficiency), alopecia, and delayed wound healing. Therefore, it is important to associate the existence of mutations or dysregulation in Zn transporters and Zn deficiency with skin manifestations.

Zinc as a Gatekeeper of Immune Function

After the discovery of zinc deficiency in the 1960s, it soon became clear that zinc is essential for the function of the immune system. Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells. Zinc homeostasis is largely controlled via the expression and action of zinc "importers" (ZIP 1-14), zinc "exporters" (ZnT 1-10), and zinc-binding proteins. Anti-inflammatory and anti-oxidant properties of zinc have long been documented, however, underlying mechanisms are still not entirely clear. Here, we report molecular mechanisms underlying the development of a pro-inflammatory phenotype during zinc deficiency. Furthermore, we describe links between altered zinc homeostasis and disease development. Consequently, the benefits of zinc supplementation for a malfunctioning immune system become clear. This article will focus on underlying mechanisms responsible for the regulation of cellular signaling by alterations in zinc homeostasis. Effects of fast zinc flux, intermediate "zinc waves", and late homeostatic zinc signals will be discriminated. Description of zinc homeostasis-related effects on the activation of key signaling molecules, as well as on epigenetic modifications, are included to emphasize the role of zinc as a gatekeeper of immune function.

Zinc Signals and Immunity

Zinc homeostasis is crucial for an adequate function of the immune system. Zinc deficiency as well as zinc excess result in severe disturbances in immune cell numbers and activities, which can result in increased susceptibility to infections and development of especially inflammatory diseases. This review focuses on the role of zinc in regulating intracellular signaling pathways in innate as well as adaptive immune cells. Main underlying molecular mechanisms and targets affected by altered zinc homeostasis, including kinases, caspases, phosphatases, and phosphodiesterases, will be highlighted in this article. In addition, the interplay of zinc homeostasis and the redox metabolism in affecting intracellular signaling will be emphasized. Key signaling pathways will be described in detail for the different cell types of the immune system. In this, effects of fast zinc flux, taking place within a few seconds to minutes will be distinguish from slower types of zinc signals, also designated as “zinc waves”, and late homeostatic zinc signals regarding prolonged changes in intracellular zinc.

Roles of Zinc Signaling in the Immune System

Zinc (Zn) is an essential micronutrient for basic cell activities such as cell growth, differentiation, and survival. Zn deficiency depresses both innate and adaptive immune responses. However, the precise physiological mechanisms of the Zn-mediated regulation of the immune system have been largely unclear. Zn homeostasis is tightly controlled by the coordinated activity of Zn transporters and metallothioneins, which regulate the transport, distribution, and storage of Zn. There is growing evidence that Zn behaves like a signaling molecule, facilitating the transduction of a variety of signaling cascades in response to extracellular stimuli. In this review, we highlight the emerging functional roles of Zn and Zn transporters in immunity, focusing on how crosstalk between Zn and immune-related signaling guides the normal development and function of immune cells.

Zinc and immunity: An essential interrelation

The significance of the essential trace element zinc for immune function has been known for several decades. Zinc deficiency affects immune cells, resulting in altered host defense, increased risk of inflammation, and even death. The micronutrient zinc is important for maintenance and development of immune cells of both the innate and adaptive immune system. A disrupted zinc homeostasis affects these cells, leading to impaired formation, activation, and maturation of lymphocytes, disturbed intercellular communication via cytokines, and weakened innate host defense via phagocytosis and oxidative burst. This review outlines the connection between zinc and immunity by giving a survey on the major roles of zinc in immune cell function, and their potential consequences in vivo.

Screening for Zinc Deficiency in Patients with Cirrhosis: When Should We Start?

BACKGROUND

Zinc deficiency has been observed in cirrhosis, but management guidelines do not address screening for zinc deficiency. We aim to determine the prevalence of zinc deficiency in different stages of cirrhosis and to correlate zinc levels with complications of cirrhosis and clinical outcomes. Patients who had a diagnosis of cirrhosis and had serum zinc levels drawn from 2007 to 2011 were identified. Demographics, laboratory data, presence of ascites, encephalopathy, and infection were obtained; Child-Pugh and MELD scores were calculated. Stata software was used for data analysis. A total of 163 patients were included in the study.

RESULTS

The median serum zinc level was 0.47 mcg/ml (IQR 0.37-0.63); 83 % of patients were zinc deficient. Zinc deficiency was more prevalent in patients with Child-Pugh score B or C, and with MELD scores ≥15. Zinc levels were lower in alcoholic, hepatitis C, and cholestatic diseases than in other etiologies of liver disease. Zinc levels correlated with INR (r = -0.56, p < 0.001), bilirubin (r = -0.51, p < 0.001), and albumin (r = 0.68, p < 0.001), and were lower in patients with ascites (0.40 vs. 0.57 mcg/ml, p < 0.001), encephalopathy (0.40 vs. 0.53 mcg/ml, p < 0.001), diuretic use (0.45 vs. 0.535 mcg/ml, p = 0.005), and infection (0.32 vs. 0.51 mcg/ml, p < 0.001). Ascites (p = 0.044) and infection (p = 0.009) were independently associated with zinc levels. Zinc-deficient patients had lower transplant-free survival rates than non-deficient patients.

CONCLUSION

Zinc deficiency is highly prevalent in cirrhotic patients with Child-Pugh score B or C, and with MELD score ≥15. Zinc deficiency also correlates with disease severity, infection, and a worse transplant-free survival. Screening for zinc deficiency should be considered in this subset of patients.

Zinc homeostasis and immunosenescence

For more than 50 years, zinc is known to be an essential trace element, having a regulatory role in the immune system. Deficiency in zinc thus compromises proper immune function, like it is observed in the elderly population. Here mild zinc deficiency is a common condition, documented by a decline of serum or plasma zinc levels with age. This leads to a dysregulation mainly in the adaptive immunity that can result in an increased production of pro-inflammatory cytokines, known as a status called inflamm-aging. T cell activation as well as polarization of T helper (Th) cells into their different subpopulations (Th1, Th2, Th17, regulatory T cells (Treg)) is highly influenced by zinc homeostasis. In the elderly a shift of the Th cell balance towards Th2 response is observed, a non-specific pre-activation of T cells is displayed, as well as a decreased response to vaccination is seen. Moreover, an impaired function of innate immune cells indicate a predominance of zinc deficiency in the elderly that may contribute to immunosenescence. This review summarizes current findings about zinc deficiency and supplementation in elderly individuals.

Zinc and its role in age-related inflammation and immune dysfunction

Zinc is an essential micronutrient required for many cellular processes, especially for the normal development and function of the immune system. Zinc homeostasis and signaling are critical in immune activation, and an imbalance in zinc homeostasis is associated with the development of chronic diseases. Zinc deficiency causes significant impairment in both adaptive and innate immune responses, and promotes systemic inflammation. The elderly are a population particularly susceptible to zinc deficiency. National surveys indicate that a significant portion of the aged population has inadequate zinc intake, and a decline in zinc status is observed with age. There are remarkable similarities between the hallmarks of zinc deficiency and immunological dysfunction in aged individuals. Both zinc deficiency and the aging process are characterized by impaired immune responses and systemic low grade chronic inflammation. It has been hypothesized that age-related zinc deficiency may be an important factor contributing to immune dysfunction and chronic inflammation during the aging process. In this review, we discuss the effects of zinc status on aging, potential molecular and epigenetic mechanisms contributing to age-related decline in zinc status, and the role of zinc in age-related immune dysfunction and chronic inflammation.

Micronutrients and HIV infection

The immune system requires several essential micronutrients to maintain an effective immune response. HIV infection destroys the immune system and promotes nutritional deficiencies, which further impair immunity. This article reviews the role of several micronutrients (vitamins A, C, E and D, the B vitamins, and minerals, selenium, iron and zinc) that are relevant for maintaining immune function. In addition, the deficiencies of these micronutrients have been associated with faster progression of HIV-1 disease. This review examines the evidence from observational studies of an association between micronutrient status and HIV disease, as well as the effectiveness of micronutrient supplementation on HIV-disease progression, pregnancy outcomes and nutritional status, among others, utilizing randomized clinical trials. Each micronutrient is introduced with a summary of its functions in human physiology, followed by the presentation of studies conducted in HIV-infected patients in relation to this specific micronutrient. Overall findings and recommendations are then summarized.

Role of dietary zinc in heat-stressed poultry: a review

High ambient temperatures compromise performance and productivity through reducing feed intake and decreasing nutrient utilization, growth rate, egg production, egg quality, and feed efficiency, which lead to economic losses in poultry. Environmental stress also leads to oxidative stress associated with a reduced antioxidant status in the bird in vivo, as reflected by increased oxidative damage and lowered plasma concentrations of antioxidant vitamins (e.g., vitamins E, A, and C) and minerals (e.g., Zn). Zinc has an important role in numerous biological processes in avian and mammalian species. For instance, Zn is an essential component of many enzymes, and it has both structural and catalytic functions in metalloenzymes. Furthermore, dietary Zn is required for normal immune function as well as proper skeletal development and maintenance. One of the most important functions of Zn is related to its antioxidant role and its participation in the antioxidant defense system. This work compiles past and present information about the role of Zn in heat-stressed poultry health.

Immunomodulative effect of glucan and/or glucan supplemented with zinc in albendazole therapy for murine alveolar echinococcosis

The effect of glucan immunomodulator (GI) and glucan supplemented with zinc (GIZn) administered separately or with albendazole (ABZ) on cellular immunity of mice with alveolar echinococcosis was observed. The stimulative effect of GI and GI + ABZ therapy on proliferative response of T lymphocytes was prolonged by GIZn or GIZn + ABZ from week 6 to 14 postinfection (p.i.). The increased proliferation of B lymphocytes was observed during combined therapies GI + ABZ and GIZn + ABZ from week 6 to 12 p.i. Number of splenic CD4 T cells in mice with GI or GI + ABZ therapy was increased only on weeks 6 and 8 p.i. GIZn and GIZn + ABZ therapy prolonged this stimulation from week 6 to 14 p.i. Serum concentration of interferon-gamma (IFN-gamma) was increased after GIZn therapy and reduced after GI therapy from week 8 to 12 p.i. GIZn + ABZ therapy had the highest effect on the IFN-gamma rise from week 8 to 22 p.i. Both GI and GIZn inhibited the serum concentration of interleukin-5 (IL-5) from week 6 p.i. The production of superoxide anion was increased after GI therapy from week 6 to 14 p.i. and after GI + ABZ or GIZn + ABZ therapies from week 12 to 18 p.i. The most effective antiparasitic therapy for alveolar echinococcosis was reached by GIZn + ABZ therapy.

Immunological changes in growing mice fed on diets containing casein or peas (Pisum sativum var. Belinda) as the source of protein

The effects of two different sources of protein: peas (Pisum sativum var. Belinda) and casein on immunocompetence, nutritional utilization and growth performance have been investigated in recently weaned mice. Feeding these animals on a pea diet resulted in an impairment in growth and significant decreases in the weights of liver, muscle, kidneys and femur, while intestine weights increased. No differences in food consumption were observed, but food conversion efficiency (food intake: weight gain) was increased in pea-fed animals compared with those offered the casein diet. Packed cell volume and serum Fe and Zn levels fell significantly after legume-protein intake, and, by contrast, Cu values increased slightly. Serum albumin levels showed a statistically significant reduction in mice fed on the diet containing peas. However, y-globulins and immunoglobulin G titres were markedly increased. The characterization of spleen-cell subsets using monoclonal antibodies revealed a significantly higher percentage of T-lymphocytes in the pea group compared with casein-fed animals, while no changes were observed in the proportions of B-lymphocytes and macrophages. In vitro mitogenic responses to phytohaemagglutinin, concanavalin A and Escherichia coli lipopolysaccharide S were slightly, but not significantly, lower in the pea-fed animals. Our results describe, apparently for the first time in mice, some immunological disturbances after peak intake. These results may lead to a better understanding of the possible role of antigenic proteins in gastrointestinal disorders and the poor individual performance after legume intake.

Zinc and skin health: overview of physiology and pharmacology

BACKGROUND

Zinc is known to have a critical role in overall human physiology, which likely explains many of its therapeutic uses for the last several thousand years. The specific roles zinc plays in skin health and function are less widely known yet are likely just as critical based on the manifestations of dietary zinc deprivation, which include moderate to severe dermatitis.

OBJECTIVE

To provide a critical review of the scientific literature as to the physiologic importance of zinc to skin, the biochemical basis for these effects, and pharmacologic aspects of zinc therapeutics.

RESULTS AND CONCLUSIONS

Skin is in a continual state of renewal, placing a high demand on zinc-based enzymes and proteins that direct this process. The importance of zinc physiologically is especially evident in studies of wound healing and inflammation reduction. During these processes, the high needs for zinc can be supplemented externally, generally increasing the rates of the natural processes. Topical zinc delivery involves the pharmacologic optimization of zinc delivery, often mediated by the solubility of the zinc material and interactions within the product matrix.

Toxic epidermal necrolysis: current evidence, practical management and future directions

Toxic epidermal necrolysis (TEN) is a rare disorder characterized by extensive epidermal death. Almost all cases appear to be caused by an idiosyncratic drug reaction. Proposed pathogenic mechanisms are conflicting, and the evidence for the benefits of individual treatments is inadequate, and in some cases contradictory. The mortality rate remains high. We review the literature pertaining to the pathogenesis of TEN and drug reactions in general. The rationale for therapeutic interventions, together with reported evidence of efficacy, are considered. We present a composite model of TEN, based on previous work and suggested pathogeneses of TEN, mechanisms of drug reactions and reported cytotoxic lymphocyte (CTL) cytolytic pathways. In this system, TEN, like some other cutaneous drug eruptions, is an HLA class I-restricted, specific drug sensitivity, resulting in clonal expansion of CD8+ CTLs. Cytotoxicity is mediated by CTL granzyme and possibly death receptor (DR) ligand (DR-L), probably Fas ligand (FasL). Particular to TEN, there is then an amplification sequence involving further DR-L expression. FasL is likely to be particularly important but tumour necrosis factor (TNF) may well contribute, via the TNF receptor 1 (TNF-R1) death pathway. Alternatively, we suggest the possibility of upregulation of an antiapoptotic TNF-R1-nuclear factor kappaB pathway, which would proscribe treatments which downregulate this pathway. None of the published data on individual treatment efficacies is sufficiently strong to suggest a definitive single treatment. Currently a multifaceted regimen appears indicated, targeting various likely intermediary mechanisms, including elimination of residual drug, immunosuppression, inhibition of DR pathways, general antiapoptotic strategies, and aggressive supportive care. Particular attention has been directed at avoiding potential conflicts between different treatments and avoiding agents that theoretically might have a net proapoptotic rather than antiapoptotic effect. Nursing on a specialized unit is of paramount importance.

Immune system and cardiac functions of progeny chicks from dams fed diets differing in zinc and manganese level and source

This research was conducted to evaluate immunity (experiments 1 to 3), cardiac function, and ascities resistance (experiment 4) of progeny chicks from broiler breeders fed diets differing in trace metal level and source. Broiler breeders received a control diet (75 mg of Zn and 83 mg of Mn added/kg of diet), the control diet supplemented with inorganic Zn (75 mg/kg of diet) and Mn (80 mg/kg of diet), the control diet supplemented with organic Zn (75 mg/kg of diet) and inorganic Mn (80 mg/kg of diet), or the control diet supplemented with organic Zn (75 mg/kg of diet) and Mn (80 mg/kg of diet) in experiments 1, 2, and 3. In experiment 4, the control diet and diet supplemented with organic sources of Zn and Mn were fed to broiler breeders. Immune organ weights, circulating granulocytes vs. agranulocytes, CD4 and CD8 positive T cells, cutaneous basophil hypersensitivity, and antibody titers to SRBC and breeder vaccinations were measured in progeny. Some supplemental mineral treatments increased (P < or = 0.05) cutaneous basophil hypersensitivity and relative bursa weight. All supplemental mineral treatments increased (P < or = 0.05) relative thymus weight. In experiment 4, electrocardiograph, pulse oximetry, heart rate, hematocrits, ventricle weights, and ascites incidence were measured in progeny reared in a cold-stress environment. The supplemental organic minerals increased (P < or = 0.05) left ventricle plus septum and total ventricular weights. Although progeny ascites incidence did not differ between breeder mineral treatments, breeders fed supplemental Zn and Mn sired progeny with improved cardiac functional capacity and some improvements in immunity.

Zinc-altered immune function

Zinc is known to be essential for all highly proliferating cells in the human body, especially the immune system. A variety of in vivo and in vitro effects of zinc on immune cells mainly depend on the zinc concentration. All kinds of immune cells show decreased function after zinc depletion. In monocytes, all functions are impaired, whereas in natural killer cells, cytotoxicity is decreased, and in neutrophil granulocytes, phagocytosis is reduced. The normal functions of T cells are impaired, but autoreactivity and alloreactivity are increased. B cells undergo apoptosis. Impaired immune functions due to zinc deficiency are shown to be reversed by an adequate zinc supplementation, which must be adapted to the actual requirements of the patient. High dosages of zinc evoke negative effects on immune cells and show alterations that are similar to those observed with zinc deficiency. Furthermore, when peripheral blood mononuclear cells are incubated with zinc in vitro, the release of cytokines such as interleukins (IL)-1 and -6, tumor necrosis factor-alpha, soluble IL-2R and interferon-gamma is induced. In a concentration of 100 micro mol/L, zinc suppresses natural killer cell killing and T-cell functions whereas monocytes are activated directly, and in a concentration of 500 micro mol/L, zinc evokes a direct chemotactic activation of neutrophil granulocytes. All of these effects are discussed in this short overview.

A rare case of ulcerative colitis complicating Wilson's disease: possible association between the two diseases

A case of ulcerative colitis complicated by Wilson's disease is described. In this case, ulcerative colitis occurred 12 years after the diagnosis of Wilson's disease, and the colitis was intractable to prednisolone and salazosulfapyridine. Because copper is one of the trace elements necessary for antioxidant defenses during inflammatory process, altered copper metabolism may have contributed to the intractability of the ulcerative colitis in this case.

Zinc intervention on macrophages and lymphocytes response

Normal zinc levels are essential for the development and maintenance of immune functions; Zn deficiency is detrimental to the embryo and offspring of experimental animals, especially concerning immune development. It is known that Zn supplementation improves immune responses. To further explore the relation between Zn administration and the metal in vitro effects, we studied zinc (500 mg/l) supplementation impact on lymphocytes and macrophages and zinc in vitro effects, in BALB/c mice supplemented from gestation to lactation. Results show a significant increase in proliferation (assessed by 3H incorporation) in lymphocytes exposed to Zn (0.1 mM) in vitro, in 3-wk-old mice; this effect is annulled when the supplementation period is lengthened, indicating saturation of the mechanisms involved in zinc induced stimulation. Macrophages functional capacity assessed by erythrophagocytosis was also improved by Zn supplementation and furthermore by the in vitro exposure to the metal, in mice 3 wk old, this was also depressed by Zn accumulation due to the supplementation period extension (9 weeks). Results show an improvement in the immune parameters analysed due to zinc supplementation and to zinc in vitro exposure. Results also suggest the accumulation of zinc as a result of prolonged supplementation periods, suppresses the cells response to zinc in vitro.

Zinc and the immune system

Zn is an essential trace element for all organisms. In human subjects body growth and development is strictly dependent on Zn. The nervous, reproductive and immune systems are particularly influenced by Zn deficiency, as well as by increased levels of Zn. The relationship between Zn and the immune system is complex, since there are four different types of influence associated with Zn. (1) The dietary intake and the resorption of Zn depends on the composition of the diet and also on age and disease status. (2) Zn is a cofactor in more than 300 enzymes influencing various organ functions having a secondary effect on the immune system. (3) Direct effects of Zn on the production, maturation and function of leucocytes. (4) Zn influences the function of immunostimulants used in the experimental systems. Here we summarize all four types of influence on the immune function. Nutritional aspects of Zn, the physiology of Zn, the influence of Zn on enzymes and cellular functions, direct effects of Zn on leucocytes at the cellular and molecular level, Zn-altered function of immunostimulants and the therapeutic use of Zn will be discussed in detail.

The dynamic link between the integrity of the immune system and zinc status

The results of more than three decades of work indicate that zinc deficiency rapidly diminishes antibody- and cell-mediated responses in both humans and animals. The moderate deficiencies in zinc noted in sickle cell anemia, renal disease, chronic gastrointestinal disorders and acrodermatitis enteropathica; subjects with human immunodeficiency virus; children with diarrhea; and elderly persons can greatly alter host defense systems, leading to increases in opportunistic infections and mortality rates. Conversely, short periods of zinc supplementation substantially improve immune defense in individuals with these diseases. Mouse models demonstrate that 30 d of suboptimal intake of zinc can lead to 30-80% losses in defense capacity. Collectively, the data clearly demonstrate that immune integrity is tightly linked to zinc status. Lymphopenia and thymic atrophy, which were the early hallmarks of zinc deficiency, are now known to be due to high losses of precursor T and B cells in the bone marrow. This ultimately leads to lymphopenia or a failure to replenish the lymphocytic system. Glucocorticoid-mediated apoptosis induced by zinc deficiency causes down-regulation of lymphopoiesis. Indeed, zinc itself can modulate death processes in precursor lymphocytes. Finally, there is substantial evidence that zinc supplementation may well reduce the impact of many of the aforementioned diseases by preventing the dismantling of the immune system. The latter represents an important area for research.

Zinc status in human immunodeficiency virus infection

There is substantial evidence to support an important role for zinc in immune processes. Adequate zinc status is essential for T-cell division, maturation and differentiation; lymphocyte response to mitogens; programmed cell death of lymphoid and myeloid origins; gene transcription; and biomembrane function. Lymphocytes are one of the types of cells activated by zinc. Zinc is the structural component of a wide variety of proteins, neuropeptides, hormone receptors and polynucleotides. Among the best known zinc-dependent hormones/enzymes are Cu, Zn superoxide dismutase, an enzyme component of the antioxidant defense system, and thymulin, which is essential for the formation of T-lymphocytes. In animals and humans, zinc deficiency results in rapid and marked atrophy of the thymus, impaired cell-mediated cutaneous sensitivity and lymphopenia. Primary and secondary antibody responses are reduced in zinc deficiency, particularly for those antigens that require T-cell help, such as those in heterologous red blood cells. In addition, antibody response and the generation of splenic cytotoxic T cells after immunization are reduced. Zinc also inhibits the production of tumor necrosis factor, which is implicated in the pathophysiology of cachexia and wasting in acquired immune deficiency syndrome.

Therapeutic application of zinc in human immunodeficiency virus against opportunistic infections

The relevance of zinc in resistance to infections by virus, fungi and bacteria is recognized because of its pivotal role in the efficiency of the entire immune system, in particular in conferring biological activity to a thymic hormone called thymulin, which has differentiation properties on T-cell lines. In infection with human immunodeficiency virus (HIV), the zinc-bound form of thymulin (active thymulin, ZnFTS) is strongly reduced in stage IV of the disease (Centers for Disease Control and Prevention classification) with concomitant decrements in CD4(+) cell count and zincemia values. The zinc-unbound form of thymulin (inactive thymulin, FTS) is, in contrast, very high. The in vitro addition of zinc to plasma samples induces a recovery of the thymulin active form, suggesting low zinc bioavailability as the cause of impaired thymic functions with consequent CD4(+) depletion. An analysis of risk factors for the incidence of recidivism opportunistic infections shows CD4(+) depletion and zinc deficiency to have significant scores. Supplementation with zinc for 1 mo (45 mg Zn(2+)/d) associated with zidovudine (AZT) therapy in stage IV induces recovery of active zinc-bound thymulin, of zincemia, of CD4(+) cells with concomitant reduction (50%) of recidivism opportunistic infections compared with the AZT-treated group. Complete disappearance of recidivism by Candida aesophagea or Pneumocystis carinii is observed after supplementation with zinc. The relative risk factors (CD4(+) depletion and zinc-deficiency) have lower scores in the HIV-positive zinc-treated group, confirming, as such, the relevance of zinc in opportunistic infections that involve extracellular matrix. Such an assumption is indirectly confirmed with new HAART, where no opportunistic infections occur. Indeed, HIV RNA is inversely correlated with both CD4(+) and zincemia values (r = -0.73, P<0.01) in HAART-treated subjects. Lower scores for the same relative factors for the appearance of opportunistic infections are present in HAART-treated subjects compared with those treated with AZT. These findings, on the one hand, show the poor efficacy of AZT therapy compared with HAART therapy for the progression of HIV, but on the other hand, they suggest that the lack of occurrence of opportunistic infections by HAART may also result from major zinc bioavailability. This further supports the key role played by zinc against opportunistic infections in HIV with a possible independent effect by either HIV or the pathogens involved.

Zinc-altered immune function and cytokine production

Although the intriguing role of zinc as an essential trace element for immune function is well established, particular progress in determining the molecular principles of action of this ion was made recently. Leukocyte responsiveness is delicately regulated by zinc concentration. Zinc deficiency as well as supraphysiologic levels impair immune function. Furthermore, the activities of many immunostimulants frequently used in immunologic studies are influenced by zinc concentration. Therefore, our knowledge from in vitro studies is widely dependent on the zinc concentration, and when not in physiologic range, immunologic responses are artificially low. Decreased production of TH1 cytokines and interferon-alpha by leukocytes in the healthy elderly person is correlated with low zinc serum level. The defect in interferon-alpha production is reconstituted by the addition of physiologic amounts of zinc in vitro. Interestingly, zinc induces cytokine production by isolated leukocytes. Zinc induces monocytes to produce interleukin-1, interleukin-6 and tumor necrosis factor-alpha in peripheral blood mononuclear cells and separated monocytes. This effect is higher in serum-free medium. However, only in the presence of serum does zinc also induce T cells to produce lymphokines. This effect on T cells is mediated by cytokines produced by monocytes. Stimulation also requires cell-to-cell contact of monocytes and T cells. Information is presented to illustrate the concepts that the zinc concentration must be taken into account whenever in vitro studies are made or complex alterations of immune functions are observed in vivo.

Decreased natural killer (NK) cell activity in zinc-deficient rats

1. In the study, the effect of zinc deficiency, a natural killer (NK), and lipopolysaccharide (LPS) activated NK cell activity were investigated. 2. Rats were fed with zinc-deficient and normal diet for 3 weeks. 3. NK and LPS activated NK cell activity was 7.2 +/- 1.8%/10(6) cells (n = 10) and 9.5 +/- 4.3%/10(6) cells (n = 10), respectively, in the zinc deficient group. In the control group fed with normal diet, NK and LPS activated NK cell activity was 22.2 +/- 3.3%/10(6) cells (n = 10) and 32.5 +/- 3.5%/10(6) cells (n = 10), respectively. 4. Plasma zinc concentration was 131.7 +/- 8.8 micrograms/dl in the zinc-deficient group and 206 +/- 17.7 micrograms/dl in the control group. 5. The results suggest that decreased NK and LPS activated NK cell activity is associated with zinc deficiency.

Zinc deficiency impairs T cell function in mice with primary infection of Heligmosomoides polygyrus (Nematoda)

This study was designed to determine whether severe zinc deficiency would prolong the course of a primary Heligmosomoides polygyrus infection in mice, and whether this could be related to impaired T cell function. Female BALB/c mice were fed a zinc-sufficient (Zn+; 60 mg/kg), a zinc-deficient (Zn-; 0.75 mg/kg) or an energy restricted (PF; 60 mg zinc/kg) diet. After four weeks, some mice in each dietary group were given a primary infection with 100 larvae; nutritional, parasitological and immunological parameters were assayed over the following five weeks. Liver zinc concentrations were significantly reduced in Zn- mice compared with Zn+ mice. In certain cases, PF mice also had reduced liver zinc concentrations, showing the negative effects of restricted food intake on zinc status. Zinc deficiency prolonged the course of a primary infection, with the effects being most evident five weeks post-infection when Zn+ mice had only 40% as many worms as Zn- mice. Parasite infection induced strong immunological responses in Zn+ mice in contrast to Zn- mice. The reduced production of IL-4 and IFN-gamma, the reduced peripheral eosinophilia and reduced serum levels of IgE and IgG1 in Zn- mice were attributed to the zinc deficiency, whereas the reduced delayed type hypersensitivity response to parasite antigen and reduced production of IL-5 were in certain instances attributed to reduced energy intake rather than zinc deficiency. These results show that zinc deficiency significantly impairs functions normally attributed to both Th1 and Th2 cell populations, and that these alterations are associated with elevated worm numbers in zinc-deficient mice.

Interleukin-2 production is altered by copper deficiency

Copper is an essential nutrient for optimal function of the immune system; deficiency results in impairment of both humoral and cell-mediated components. Copper deficiency in rodents results in decreased numbers of CD4+ (helper) and total T cells. This defect has been traced to impaired production of interleukin-2, a cytokine essential for T-cell division and differentiation. Impairment of quiescent cell proliferation is reversed by both in vivo and in vitro copper supplementation.

Functional capacity of the residual lymphocytes from zinc-deficient adult mice

Zn deficiency has been shown to reduce host defence drastically. It was of interest to determine the capacity of the residual lymphocytes from Zn-deficient mice to proliferate and produce lymphokines in response to stimulation since there are many Zn-dependent metalloenzymes that might be altered by the deficiency. To address this question, young adult A/J mice were provided Zn-deficient or Zn-adequate diets or restricted amounts of a Zn-adequate diet for 30 d. Splenocytes from moderately or severely Zn-deficient adult A/J mice gave normal proliferative responses and generated adequate interleukin II (IL-2) activity when stimulated with the mitogen Concanavalin A. However, splenocytes from deficient mice exhibited a higher degree of proliferation (about 150%) and production of IL-2 in response to foreign target cells compared with T-cells prepared from mice provided a Zn-adequate diet. B-cells from deficient mice stimulated in vivo with sheep erythrocytes produced fewer total numbers of plaque-forming cells (PFC) per spleen. Nevertheless, the proportion or number of PFC/10(6) viable splenocytes and the amounts of IgM and IgG antibody produced per PFC were equivalent to those of adequately-fed and restricted-fed controls. The previously described responses were not significantly affected by whether the level of Zn in the culture medium was adequate or limiting. Based on these tests it appeared that the residual splenic lymphocytes of Zn-deficient mice were able to carry out many fundamental immune processes.

Nutritional outcome and immunocompetence in mice fed on a diet containing raw field beans (Vicia faba, var. minor) as the source of protein

Feeding growth mice on diets containing raw field beans (Vicia faba var. minor) as the only source of protein brought about an impairment in growth, muscle mass and liver weight. No changes in food consumption were observed, but the food intake:weight gain ratio was increased in those animals. Plasma protein, triacylglycerols and cholesterol values were not affected by the dietary treatment although serum glucose and zinc levels fell after legume intake as well as the number of circulating erythrocytes. The relative enlargement of thymus and spleen in the legume-fed mice was apparently accompanied by a reduction in the cell number and an increase in cell size, while the protein synthesis capacity followed differentiated patterns in both tissues when assessed through protein, DNA and RNA determinations. The haemagglutination titres and the number of rosette-forming cells were lower in those animals fed on the field bean diet as well as the splenic lymphocyte responses to phytohaemagglutinin, Concanavalin A or lipopolysaccharide mitogens used to evaluate the functional status of T and B lymphocytes. The present study describes, apparently for the first time in mice, the involvement of field bean intake in some immunological disturbances affecting both humoral- and cell-mediated aspects of the immune response.

Copper deficiency reversibly impairs DNA synthesis in activated T lymphocytes by limiting interleukin 2 activity

The essentiality of adequate copper (Cu) nutriture for normal T-cell function in laboratory and domestic animals is well established. However, specific biochemical roles of Cu in the maturation and activation of T cells have not been defined. Previous work showed that when cultures of splenic mononuclear cells (MNCs) from Cu-deficient rats were exposed to T-cell mitogens, DNA synthesis was markedly reduced despite normal up-regulation of interleukin 2 (IL-2) receptors, transferrin receptors, and class II major histocompatibility complex molecules. In the present study, IL-2 activity in PHA-treated cultures of MNCs from Cu-deficient rats was 40-50% that of controls as determined by bioassay. Addition of rat IL-2 to phytohemagglutinin-treated cultures of MNCs from Cu-deficient rats increased blastogenic activity to control levels, demonstrating that Cu deficiency does not inhibit transition of quiescent cells to the competence phase of the activation process. Moreover, supplementation of MNC cultures from Cu-deficient rats with physiological levels of Cu enhanced IL-2 activity and DNA synthesis in response to phytohemagglutinin. These data indicate that IL-2 activity in cultures of activated splenic T lymphocytes from Cu-deficient rats is insufficient for optimal blastogenesis.