Zinc and immunity: An essential interrelation

Individual risk management strategy and potential therapeutic options for the COVID-19 pandemic

It is an ugly fact that a significant amount of the world's population will contract SARS-CoV-II infection with the current spreading. While a specific treatment is not yet coming soon, individual risk assessment and management strategies are crucial. The individual preventive and protective measures drive the personal risk of getting the disease. Among the virus-contracted hosts, their different metabolic status, as determined by their diet, nutrition, age, sex, medical conditions, lifestyle, and environmental factors, govern the personal fate toward different clinical severity of COVID-19, from asymptomatic, mild, moderate, to death. The careful individual assessment for the possible dietary, nutritional, medical, lifestyle, and environmental risks, together with the proper relevant risk management strategies, is the sensible way to deal with the pandemic of SARS-CoV-II.

Zinc Iodide in combination with Dimethyl Sulfoxide for treatment of SARS-CoV-2 and other viral infections

Zinc Iodide and Dimethyl Sulfoxide compositions are proposed as therapeutic agents to treat and prevent chronic and acute viral infections including SARS-CoV-2 infected patients. The therapeutic combinations have a wide range of virucidal effects on DNA and RNA containing viruses. The combinations also exhibit anti-inflammatory, immunomodulating, antifibrotic, antibacterial, antifungal and antioxidative effects. Given the fact that Zinc Iodide has been used as an oral antiseptic agent and DMSO has been already proven as a safe pharmaceutical solvent and therapeutic agent, we hypothesize that the combination of these two agents can be applied as an effective, safe and inexpensive treatment for SARS-CoV-2 and other viral infection. The therapeutic compound can be applied as both etiological and pathogenesis therapy and used as an effective and safe antiseptic (disinfectant) for human and animals as well.

Type I Interferons Ameliorate Zinc Intoxication of Candida glabrata by Macrophages and Promote Fungal Immune Evasion

Host and fungal pathogens compete for metal ion acquisition during infectious processes, but molecular mechanisms remain largely unknown. Here, we show that type I interferons (IFNs-I) dysregulate zinc homeostasis in macrophages, which employ metallothionein-mediated zinc intoxication of pathogens as fungicidal response. However, Candida glabrata can escape immune surveillance by sequestering zinc into vacuoles. Interestingly, zinc-loading is inhibited by IFNs-I, because a Janus kinase 1 (JAK1)-dependent suppression of zinc homeostasis affects zinc distribution in macrophages as well as generation of reactive oxygen species (ROS). In addition, systemic fungal infections elicit IFN-I responses that suppress splenic zinc homeostasis, thereby altering macrophage zinc pools that otherwise exert fungicidal actions. Thus, IFN-I signaling inadvertently increases fungal fitness both in vitro and in vivo during fungal infections. Our data reveal an as yet unrecognized role for zinc intoxication in antifungal immunity and suggest that interfering with host zinc homeostasis may offer therapeutic options to treat invasive fungal infections.

Nutrition, immunity and COVID-19

The immune system protects the host from pathogenic organisms (bacteria, viruses, fungi, parasites). To deal with this array of threats, the immune system has evolved to include a myriad of specialised cell types, communicating molecules and functional responses. The immune system is always active, carrying out surveillance, but its activity is enhanced if an individual becomes infected. This heightened activity is accompanied by an increased rate of metabolism, requiring energy sources, substrates for biosynthesis and regulatory molecules, which are all ultimately derived from the diet. A number of vitamins (A, B6, B12, folate, C, D and E) and trace elements (zinc, copper, selenium, iron) have been demonstrated to have key roles in supporting the human immune system and reducing risk of infections. Other essential nutrients including other vitamins and trace elements, amino acids and fatty acids are also important. Each of the nutrients named above has roles in supporting antibacterial and antiviral defence, but zinc and selenium seem to be particularly important for the latter. It would seem prudent for individuals to consume sufficient amounts of essential nutrients to support their immune system to help them deal with pathogens should they become infected. The gut microbiota plays a role in educating and regulating the immune system. Gut dysbiosis is a feature of disease including many infectious diseases and has been described in COVID-19. Dietary approaches to achieve a healthy microbiota can also benefit the immune system. Severe infection of the respiratory epithelium can lead to acute respiratory distress syndrome (ARDS), characterised by excessive and damaging host inflammation, termed a cytokine storm. This is seen in cases of severe COVID-19. There is evidence from ARDS in other settings that the cytokine storm can be controlled by n-3 fatty acids, possibly through their metabolism to specialised pro-resolving mediators.

Zinc Deficiency Promotes Testicular Cell Apoptosis in Mice

Zinc (Zn) plays an important role in spermatogenesis, and carbon tetrachloride (CCl₄) induces testicular oxidative damage and cell death. The objective of the present study was to define the effects of Zn deficiency in combination with CCl₄ treatment on testicular apoptosis and the associated mechanisms. Mice were fed the following diets with three different Zn levels for 6 weeks: normal zinc (ZN) diet (30 mg Zn/kg), zinc-deficient (ZD) diet (2 mg Zn/kg), and adequate zinc (ZA) diet (100 mg Zn/kg). Beginning in the third week, CCl₄ was intraperitoneally injected into half of the mice in each diet group six times over 3 weeks. We found that Zn was distributed in various tissues and organs in normal mice and that the zinc content in the testis of normal mice was high. The Zn-deficient diet reduced the zinc concentration in the testis tissue, and the testicular/body weight ratio significantly decreased. Moreover, the TUNEL results proved that CCl₄ stimulation of mice fed with a zinc-deficient diet caused marked apoptosis of testicular cells. Furthermore, the ROS levels in the testes obviously increased after Zn-deficient mice were stimulated with CCl₄, whereas reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) showed reduced activities. In addition, proteins associated with the apoptosis signaling pathway were detected with ELISA kits. P-p53, cleaved caspase-3, cleaved PRAP, p-Bad, p-JNK, p-ERK, and p-NF-κB p65 increased by varying degrees under zinc deficiency or CCl₄ stimulation. All the data indicated that Zn deficiency significantly enhanced the harm to the testis induced by oxidative stress and damage, while CCl₄ stimulation exacerbated the oxidative damage in testicular cells, leading to apoptosis through the activation of p53, MAPK, and NF-κB.

Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections

Public health practices including handwashing and vaccinations help reduce the spread and impact of infections. Nevertheless, the global burden of infection is high, and additional measures are necessary. Acute respiratory tract infections, for example, were responsible for approximately 2.38 million deaths worldwide in 2016. The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid play important and complementary roles in supporting the immune system. Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections and as a consequence an increase in disease burden. Against this background the following conclusions are made: (1) supplementation with the above micronutrients and omega-3 fatty acids is a safe, effective, and low-cost strategy to help support optimal immune function; (2) supplementation above the Recommended Dietary Allowance (RDA), but within recommended upper safety limits, for specific nutrients such as vitamins C and D is warranted; and (3) public health officials are encouraged to include nutritional strategies in their recommendations to improve public health.

Pan-retroviral Nucleocapsid-Mediated Phase Separation Regulates Genomic RNA Positioning and Trafficking

The duality of liquid-liquid phase separation (LLPS) of cellular components into membraneless organelles defines the nucleation of both normal and disease processes including stress granule (SG) assembly. From mounting evidence of LLPS utility by viruses, we discover that HIV-1 nucleocapsid (NC) protein condenses into zinc-finger (ZnF)-dependent LLPSs that are dynamically influenced by cytosolic factors. ZnF-dependent and Zinc (Zn2+)-chelation-sensitive NC-LLPS are formed in live cells. NC-Zn2+ ejection reverses the HIV-1 blockade on SG assembly, inhibits NC-SG assembly, disrupts NC/Gag-genomic RNA (vRNA) ribonucleoprotein complexes, and causes nuclear sequestration of NC and the vRNA, inhibiting Gag expression and virus release. NC ZnF mutagenesis eliminates the HIV-1 blockade of SG assembly and repositions vRNA to SGs. We find that NC-mediated, Zn2+-coordinated phase separation is conserved among diverse retrovirus subfamilies, illustrating that this exquisitely evolved Zn2+-dependent feature of virus replication represents a critical target for pan-antiretroviral therapies.

Fluctuation of biochemical, immunological, and antioxidant biomarkers in the blood of beluga (Huso huso) under effect of dietary ZnO and chitosan-ZnO NPs

The objective of the present study was to investigate the effects of dietary supplementation with zinc oxide (ZnO) and chitosan-zinc nanoparticles (chitosan-ZnO NPs) on biochemical, immunological, and antioxidant biomarkers in blood of juvenile belugas (Huso huso). The beluga juveniles with initial weight of 287 ± 46 g were fed with eight experimental diets containing 0 g kg^-1 ZnO (the control diet); 10, 20, and 40 mg kg^-1 ZnO; and 10, 20, and 40 mg kg^-1 chitosan-ZnO NPs and 36 mg kg^-1 chitosan. After 28 days of culture, the fish were fed with ZnO and chitosan-ZnO NP-supplemented diets showed a more significant increase in total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activity (p < 0.05) compared to the control group. There were no significant differences (p > 0.05) in malondialdehyde (MDA) and glucose level in all treatment groups. The results showed that with increasing levels of ZnO and chitosan-ZnO NPs, alternative complement activity (ACH50), and total immunoglobulin, total protein, albumin, and lysozyme had a significant increase in fish fed with ZnO and chitosan-ZnO NP-supplemented diets compared to the control group (p < 0.05). ALP, ALT, and AST enzyme activities showed significant difference between control and treatment groups (p > 0.05), while the levels of LDH enzyme activity, urea, and creatinine decreased by increasing both ZnO and chitosan-ZnO NP levels. These results demonstrated that dietary chitosan-ZnO NPs could improve the health status, immune function, and antioxidant capacity of the cultured beluga juvenile.

Potential interventions for novel coronavirus in China: A systematic review

An outbreak of a novel coronavirus (COVID‐19 or 2019‐CoV) infection has posed significant threats to international health and the economy. In the absence of treatment for this virus, there is an urgent need to find alternative methods to control the spread of disease. Here, we have conducted an online search for all treatment options related to coronavirus infections as well as some RNA‐virus infection and we have found that general treatments, coronavirus‐specific treatments, and antiviral treatments should be useful in fighting COVID‐19. We suggest that the nutritional status of each infected patient should be evaluated before the administration of general treatments and the current children's RNA‐virus vaccines including influenza vaccine should be immunized for uninfected people and health care workers. In addition, convalescent plasma should be given to COVID‐19 patients if it is available. In conclusion, we suggest that all the potential interventions be implemented to control the emerging COVID‐19 if the infection is uncontrollable.

Effect of Zinc Source and Exogenous Enzymes Supplementation on Zinc Status in Dogs Fed High Phytate Diets

Zinc is an essential element, a cofactor of many enzymes, and performs catalytic, structural and regulatory functions. Once in the gastrointestinal tract, zinc can interact with food constituents. Phytic acid, the major phosphorus storage in plants, limits zinc availability from animal feeds due to the formation of insoluble complexes with phytates. This study tested the effect of supplemental zinc source (zinc sulfate and a chelate zinc proteinate) and the addition of exogenous enzymes from a solid-state fermentation product of Aspergillus niger to a high phytate diet. The study was designed according to three Latin Squares 4 × 4 with a 2 × 2 factorial arrangement of treatments, with four periods, four diets, and 12 young adult Beagles. Periods lasted 5 weeks each. Diets were supplemented with 75 mg/kg of zinc sulfate (IZ) or zinc proteinate (OZ), and without or with 200 mg/kg of exogenous enzymes (IZ+, OZ+). Results showed that zinc proteinate increased the bioavailability of phosphorus, yet the zinc biomarkers remained unaffected by the zinc source, with the exception of lymphocyte subsets that benefit from zinc proteinate. The use of exogenous enzymes did not affect zinc availability nor nutrient and energy digestibility.

Lowered zinc and copper levels in drug-naïve patients with major depression: Effects of antidepressants, ketoprofen and immune activation

Objectives: The aim of the present work is to examine the effects of treatment with sertraline with and without ketoprofen on serum levels of zinc and copper in association with immune-inflammatory biomarkers in drug-naïve major depressed patients.Methods: We measured serum zinc and copper, interleukin (IL)-1β, IL-4, IL-6, IL-18, interferon-γ, and transforming growth factor-β1 in 40 controls and 133 depressed patients. The clinical efficacy of the treatment was measured using the Beck Depression Inventory-II (BDI-II) at baseline and 8 weeks later.Results: We found significantly reduced serum zinc and copper in association with upregulation of all cytokines, indicating activation of the immune-inflammatory responses system (IRS) and the compensatory immune regulatory system (CIRS). Treatment with sertraline significantly increased zinc and decreased copper. During treatment, there was a significant inverse association between serum zinc and immune activation. The improvement in the BDI-II during treatment was significantly associated with increments in serum zinc coupled with attenuation of the IRS/CIRS.Conclusions: Lower zinc is a hallmark of depression, while increments in serum zinc and attenuation of the immune-inflammatory response during treatment appear to play a role in the clinical efficacy of sertraline.

The Strategy of Boosting the Immune System Under the COVID-19 Pandemic

The novel coronavirus (SARS-CoV-2) infection (COVID-19) has raised considerable concern on the entire planet. On March 11, 2020, COVID-19 was categorized by the World Health Organization (WHO) as a pandemic infection, and by March 18, 2020, it has spread to 146 countries. The first internal defense line against numerous diseases is personalized immunity. Although it cannot be claimed that personalized nutrition will have an immediate impact on a global pandemic, as the nutritional interventions required a long time to induce beneficial outcomes on immunity development, nutritional strategies are still able to clarify and have a beneficial influence on the interplay between physiology and diet, which could make a positive contribution to the condition in the next period. As such, a specific goal for every practitioner is to evaluate different tests to perceive the status of the patient, such as markers of inflammation, insulin regulation, and nutrient status, and to detect possible imbalances or deficiencies. During the process of disease development, the supplementation and addition of different nutrients and nutraceuticals can influence not only the viral replication but also the cellular mechanisms. It is essential to understand that every patient has its individual needs. Even though many nutrients, nutraceuticals, and drugs have beneficial effects on the immune response and can prevent or ameliorate viral infections, it is essential to detect at what stage in COVID-19 progression the patient is at the moment and decide what kind of nutrition intervention is necessary. Furthermore, understanding the pathogenesis of coronavirus infection is critical to make proper recommendations.

Dietary zinc and growth, carcass characteristics, immune responses, and serum biochemistry of broilers

Context Zinc (Zn) is an essential trace element, and plays an important role in growth, bone formation, feathering and appetite of broilers. Accurate supplementation of this mineral is the aim of the animal husbandry. Thus, it is crucial to optimise the Zn concentration in the diet of broilers. Aims The present study was performed to investigate the effects of dietary supplementation of Zn on the growth performance, carcass characteristics, immune responses and serum biochemistry of broilers. Methods A total of 180 1-day-old male broilers (Arbor Acres) were randomly allotted by bodyweight to one of five treatments with six replicates of six birds each. The birds were fed a Zn-unsupplemented corn–soybean meal basal diet (27.75 or 26.88 mg/kg Zn by analysis) or one of the four Zn-supplemented diets, which were the basal diet supplemented with 40, 80, 120, or 160 mg Zn /kg as Zn sulfate (reagent grade ZnSO4•7H2O), for 42 days. Key results No differences were detected on growth performance or carcass characteristics among treatment groups. However, the total protein concentration and albumin concentration tended (P = 0.09) to increase with an increasing concentration of dietary Zn. The antibody titer of Newcastle disease (ND), and alkaline phosphatase (ALP) in serum on Day 21 were significantly increased (P &lt; 0.05) as the Zn supplementation increased in broiler diets. Conclusions These results indicated that dietary Zn supplementation improves the serum antibody titer of ND and ALP activity of broilers, and 86 mg Zn/kg was appropriate for broilers when fed a corn–soybean meal diet in the early stage. Implications The present results have provided scientific basis for broiler production, and accurate supplementation of Zn would effectively improve the growth performance and reduce production costs.

The effects of zinc deficiency on homeostasis of twelve minerals and trace elements in the serum, feces, urine and liver of rats

Background

Zinc deficiency can change the concentrations of minerals and trace elements in the body. However, previous studies still had many limitations.

Objective

To reveal the effects of zinc deficiency on homeostasis of 16 minerals and trace elements.

Methods

Forty-five rats were divided randomly into three groups: normal zinc diet (30 mg/kg), low zinc diet (10 mg/kg), and pair-fed diet(30 mg/kg). The concentrations of 16 minerals and trace elements in serum, feces, urine, and liver were measured by inductively coupled plasma mass spectrometry. The excretion of 16 elements in urine and feces were calculated and compared.

Results

Zinc-deficient rats exhibited significant changes in up to 12 minerals and trace elements. The low zinc diet induced decreased excretion of zinc and concentrations of zinc in serum, feces, urine, and liver. Zinc deficiency increased feces concentrations of Mg, Cu, Se, K, Ag, Fe and Mn; decreased the concentrations of Mg, Cu, Se, K in liver and urine, and a diminished amount of Ag was observed in serum. Decreased urinary concentrations of Zn Ca, Mg, Cu, Se, K, Na, As and Cr, suggested that zinc-deficient rats increased the 9 elements’ renal reabsorption. Decreased concentrations of Ca in liver, urine, and feces, decreased excretion in urine and feces and increased serum total Ca suggested that zinc deficiency increased the redistribution of Ca in serum or other tissues. Zinc deficiency increased excretion of Cu, Se, Fe; and decreased the excretion of other 8 elements except for Ag.

Conclusions

Zinc deficiency changed the excretion, reabsorption and redistribution of 12 minerals and trace elements in rats. Our findings are the first to show that zinc deficiency alters the concentrations of Ag, Cr, and As.

Graphical abstract

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12986-019-0395-y.

A metalloproteomic analysis of interactions between plasma proteins and zinc: elevated fatty acid levels affect zinc distribution

Serum albumin is a highly abundant plasma protein associated with the transport of metal ions, pharmaceuticals, fatty acids and a variety of small molecules in the blood. Once thought of as a molecular 'sponge', mounting evidence suggests that the albumin-facilitated transport of chemically diverse entities is not independent. One such example is the transport of Zn²⁺ ions and non-esterified 'free' fatty acids (FFAs) by albumin, both of which bind at high affinity sites located in close proximity. Our previous research suggests that their transport in blood plasma is linked via an allosteric mechanism on serum albumin. In direct competition, albumin-bound FFAs significantly decrease the binding capacity of albumin for Zn²⁺, with one of the predicted consequences being a change in plasma/serum zinc speciation. Using liquid chromatography (LC), ICP-MS and fluorescence assays, our work provides a quantitative assessment of this phenomenon, and finds that in the presence of high FFA concentrations encountered in various physiological conditions, a significant proportion of albumin-bound Zn²⁺ is re-distributed amongst plasma/serum proteins. Using peptide mass fingerprinting and immunodetection, we identify candidate acceptor proteins for Zn²⁺ liberated from albumin. These include histidine-rich glycoprotein (HRG), a multifunctional protein associated with the regulation of blood coagulation, and members of the complement system involved in the innate immune response. Our findings highlight how FFA-mediated changes in extracellular metal speciation might contribute to the progression of certain pathological conditions.

Perinatal Whole Blood Zinc Status and Cytokines, Adipokines, and Other Immune Response Proteins

(1) Background: Zinc is an essential micronutrient and zinc deficiency is associated with immune dysfunction. The neonatal immune system is immature, and therefore an optimal neonatal zinc status may be important. The aim of this study was to investigate the possible association between neonatal whole blood (WB)-Zinc content and several immune markers. (2) Methods: In total, 398 healthy newborns (199 who later developed type 1 diabetes and 199 controls) from the Danish Newborn Screening Biobank had neonatal dried blood spots (NDBS) analyzed for WB-Zinc content and (i) cytokines: Interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12 (p70), interferon gamma, tumor necrosis factor alpha, and transforming growth factor beta; (ii) adipokines: leptin and adiponectin; (iii) other immune response proteins: C-reactive protein (CRP), and mannose-binding lectin (MBL), and soluble triggering receptors expressed on myeloid cells1 (sTREM-1). WB-Zinc content was determined using laser ablation inductively coupled plasma mass spectrometry. For each analyte, the relative change in mean level was modelled by a robust log-normal model regression. (3) Results: No association was found between WB-Zinc content and all the immune response markers in either the unadjusted or adjusted models overall or when stratifying by case status. (4) Conclusions: In healthy Danish neonates, WB-Zinc content was not associated with cytokines, adipokines, CRP, MBL or sTREM, which does not indicate a strong immunological function of neonatal zinc status.

The impact of apical and basolateral albumin on intestinal zinc resorption in the Caco-2/HT-29-MTX co-culture model

The molecular mechanisms of intestinal zinc resorption and its regulation are still topics of ongoing research. To this end, the application of suitable in vitro intestinal models, optimized with regard to their cellular composition and medium constituents, is of crucial importance. As one vital aspect, the impact of cell culture media or buffer compounds, respectively, on the speciation and cellular availability of zinc has to be considered when investigating zinc resorption. Thus, the present study aims to investigate the impact of serum, and in particular its main constituent serum albumin, on zinc uptake and toxicity in the intestinal cell line Caco-2. Furthermore, the impact of serum albumin on zinc resorption is analyzed using a co-culture of Caco-2 cells and the mucin-producing goblet cell line HT-29-MTX. Apically added albumin significantly impaired zinc uptake into enterocytes and buffered its cytotoxicity. Yet, undigested albumin does not occur in the intestinal lumen in vivo and impairment of zinc uptake was abrogated by digestion of albumin. Interestingly, zinc uptake, as well as gene expression studies of mt1a and selected intestinal zinc transporters after zinc incubation for 24 h, did not show significant differences between 0 and 10% serum. Importantly, the basolateral application of serum in a transport study significantly enhanced fractional apical zinc resorption, suggesting that the occurrence of a zinc acceptor in the plasma considerably affects intestinal zinc resorption. This study demonstrates that the apical and basolateral medium composition is crucial when investigating zinc, particularly its intestinal resorption, using in vitro cell culture.

A Zinpyr-1-based Fluorimetric Microassay for Free Zinc in Human Serum

Zinc is an essential trace element, making it crucial to have a reliable biomarker for evaluating an individual's zinc status. The total serum zinc concentration, which is presently the most commonly used biomarker, is not ideal for this purpose, but a superior alternative is still missing. The free zinc concentration, which describes the fraction of zinc that is only loosely bound and easily exchangeable, has been proposed for this purpose, as it reflects the highly bioavailable part of serum zinc. This report presents a fluorescence-based method for determining the free zinc concentration in human serum samples, using the fluorescent probe Zinpyr-1. The assay has been applied on 154 commercially obtained human serum samples. Measured free zinc concentrations ranged from 0.09 to 0.42 nM with a mean of 0.22 ± 0.05 nM. It did not correlate with age or the total serum concentrations of zinc, manganese, iron or selenium. A negative correlation between the concentration of free zinc and total copper has been seen for sera from females. In addition, the free zinc concentration in sera from females (0.21 ± 0.05 nM) was significantly lower than in males (0.23 ± 0.06 nM). The assay uses a sample volume of less than 10 µL, is rapid and cost-effective and allows us to address questions regarding factors influencing the free serum zinc concentration, its connection with the body's zinc status, and its suitability as a future biomarker for an individual's zinc status.

The role of zinc, copper, manganese and iron in neurodegenerative diseases

Metals are involved in different pathophysiological mechanisms associated with neurodegenerative diseases (NDDs), including Alzheimer's disease (AD), Parkinson's disease (PD) and multiple sclerosis (MS). The aim of this study was to review the effects of the essential metals zinc (Zn), copper (Cu), manganese (Mn) and iron (Fe) on the central nervous system (CNS), as well as the mechanisms involved in their neurotoxicity. Low levels of Zn as well as high levels of Cu, Mn, and Fe participate in the activation of signaling pathways of the inflammatory, oxidative and nitrosative stress (IO&NS) response, including nuclear factor kappa B and activator protein-1. The imbalance of these metals impairs the structural, regulatory, and catalytic functions of different enzymes, proteins, receptors, and transporters. Neurodegeneration occurs via association of metals with proteins and subsequent induction of aggregate formation creating a vicious cycle by disrupting mitochondrial function, which depletes adenosine triphosphate and induces IO&NS, cell death by apoptotic and/or necrotic mechanisms. In AD, at low levels, Zn suppresses β-amyloid-induced neurotoxicity by selectively precipitating aggregation intermediates; however, at high levels, the binding of Zn to β-amyloid may enhance formation of fibrillar β-amyloid aggregation, leading to neurodegeneration. High levels of Cu, Mn and Fe participate in the formation α-synuclein aggregates in intracellular inclusions, called Lewy Body, that result in synaptic dysfunction and interruption of axonal transport. In PD, there is focal accumulation of Fe in the substantia nigra, while in AD a diffuse accumulation of Fe occurs in various regions, such as cortex and hippocampus, with Fe marginally increased in the senile plaques. Zn deficiency induces an imbalance between T helper (Th)1 and Th2 cell functions and a failure of Th17 down-regulation, contributing to the pathogenesis of MS. In MS, elevated levels of Fe occur in certain brain regions, such as thalamus and striatum, which may be due to inflammatory processes disrupting the blood-brain barrier and attracting Fe-rich macrophages. Delineating the specific mechanisms by which metals alter redox homeostasis is essential to understand the pathophysiology of AD, PD, and MS and may provide possible new targets for their prevention and treatment of the patients affected by these NDDs.

The adaptive immune role of metallothioneins in the pathogenesis of diabetic cardiomyopathy: good or bad

Diabetes is a metabolic disorder characterized by hyperglycemia, resulting in low-grade systemic inflammation. Diabetic cardiomyopathy (DCM) is a common complication among diabetic patients, and the mechanism underlying its induction of cardiac remodeling and dysfunction remains unclear. Numerous experimental and clinical studies have suggested that adaptive immunity, especially T lymphocyte-mediated immunity, plays a potentially important role in the pathogenesis of diabetes and DCM. Metallothioneins (MTs), cysteine-rich, metal-binding proteins, have antioxidant properties. Some potential mechanisms underlying the cardioprotective effects of MTs include the role of MTs in calcium regulation, zinc homeostasis, insulin sensitization, and antioxidant activity. Moreover, metal homeostasis, especially MT-regulated zinc homeostasis, is essential for immune function. This review discusses aberrant immune regulation in diabetic heart disease with respect to endothelial insulin resistance and the effects of hyperglycemia and hyperlipidemia on tissues and the different effects of intracellular and extracellular MTs on adaptive immunity. This review shows that intracellular MTs are involved in naïve T-cell activation and reduce regulatory T-cell (Treg) polarization, whereas extracellular MTs promote proliferation and survival in naïve T cells and Treg polarization but inhibit their activation, thus revealing potential therapeutic strategies targeting the regulation of immune cell function by MTs.

Innate Immune Cells Speak Manganese

Some metal ions, such as Ca²⁺ and Zn²⁺, are involved in intracellular communication in immune cells by acting as second messengers. In this issue of Immunity, Wang et al. (2018) present findings implying a similar role for an additional metal ion, by showing that manganese participates in the recognition of cytoplasmic DNA.

Protein Food Matrix⁻ZnO Nanoparticle Interactions Affect Protein Conformation, but May not Be Biological Responses

Because of their nutritional value, zinc oxide (ZnO) nanoparticles (NPs) are applied as a dietary source of zinc, by direct addition to complex, multiple-component food matrices. The thereby occurring interactions of NPs with food matrices may have biological or toxic effects. In particular, NP interactions with food protein can lead to structural deformation of the latter, potentially changing its digestive efficiency and gastrointestinal absorption. In this study, interactions between ZnO NPs and a representative complex protein food matrix, skim milk, were compared with those between NPs and individual components of this food matrix (i.e., protein, saccharide, and mineral). The effects of the interactions on biological responses were investigated in terms of cytotoxicity, cellular uptake, intestinal transport, structural deformation for proteins, and digestive efficiency. The results demonstrated that the physicochemical properties of ZnO NPs were strongly influenced by the protein matrix type, leading to an increased dispersion stability in the complex protein matrix. However, these interactions did not affect cell proliferation, membrane damage, cellular uptake, intestinal transportation, or protein digestive efficiency, although a slight conformational change of proteins was observed in the presence of ZnO NPs. In conclusion, no toxic effects were observed, suggesting the safety of NPs when added to complex food matrices.

B cell activation and proliferation increase intracellular zinc levels

Zinc ions serve as second messengers in major cellular pathways, including the regulation pathways of proliferation and their proper regulation is necessary for homeostasis and a healthy organism. Accordingly, expression of zinc transporters can be altered in various cancer cell lines and is often involved in producing elevated intracellular zinc levels. In this study, human B cells were infected with Epstein–Barr virus (EBV) to generate immortalized cells, which revealed traits of tumor cells, such as high proliferation rates and an extended lifespan. These cells showed differentially altered zinc transporter expression with ZIP7 RNA and protein expression being especially increased as well as a corresponding increased phosphorylation of ZIP7 in EBV-transformed B cells. Accordingly, free zinc levels were elevated within these cells. To prove whether the observed changes resulted from immortalization or rather high proliferation, free zinc levels in in vitro activated B cells and in freshly isolated B cells expressing the activation marker CD69 were determined. Here, comparatively increased zinc levels were found, suggesting that activation and proliferation, but not immortalization, act as crucial factors for the elevation of intracellular free zinc.

Expression of zinc transporters ZIP4, ZIP14 and ZnT9 in hepatic carcinogenesis-An immunohistochemical study

INTRODUCTION

Dysregulation of both, systemic zinc levels and tissue-specific zinc transporters, is reported in chronic inflammatory and malignant liver disease (hepatocellular carcinoma, HCC). Aim of this study is to assess the expression level of three zinc transporters in liver tissue and HCC: ZIP4, ZIP14 and ZnT9.

METHODS

The study is based on tissue samples obtained from 138 patients with histologically proven HCC. Tissue specimens from tumor (n = 138) and extra-lesional specimens (n = 72) were assessed immunohistochemically for the expression of the three zinc transporters. Expression levels were semi-quantitatively scored and statistically analyzed with respect to the etiology of HCC (alcohol, AFLD; non-alcoholic fatty liver disease, NAFLD; virus-hepatitis, VH) and survival.

RESULTS

Overall, expression levels of ZIP4, ZIP14 and ZnT9 were significantly higher in HCC tissue than in adjacent extra-lesional liver tissue. Expression levels in tumor tissue and survival time revealed a negative correlation for ZIP4 and ZIP14, and in part for ZnT9 (nuclear staining) (p < 0.05), whereas cytoplasmic staining of ZnT9 did not correlate with survival. Furthermore, the expression level of ZIP4 in extra-lesional tissue showed inverse correlation with survival time.

CONCLUSION

The upregulation of zinc transporters in hepatic carcinogenesis and its negative correlation with survival time implies a regulatory/functional link between zinc-homeostasis and development/progression of HCC that deserves to be further explored.

Characterization of Caco-2 cells stably expressing the protein-based zinc probe eCalwy-5 as a model system for investigating intestinal zinc transport

Intestinal zinc resorption, in particular its regulation and mechanisms, are not yet fully understood. Suitable intestinal cell models are needed to investigate zinc uptake kinetics and the role of labile zinc in enterocytes in vitro. Therefore, a Caco-2 cell clone was produced, stably expressing the genetically encoded zinc biosensor eCalwy-5. The aim of the present study was to reassure the presence of characteristic enterocyte-specific properties in the Caco-2-eCalwy clone. Comparison of Caco-2-WT and Caco-2-eCalwy cells revealed only slight differences regarding subcellular localization of the tight junction protein occludin and alkaline phosphatase activity, which did not affect basic integrity of the intestinal barrier or the characteristic brush border membrane morphology. Furthermore, introduction of the additional zinc-binding protein in Caco-2 cells did not alter mRNA expression of the major intestinal zinc transporters (zip4, zip5, znt-1 and znt-5), but increased metallothionein 1a-expression and cellular resistance to higher zinc concentrations. Moreover, this study examines the effect of sensor expression level on its saturation with zinc. Fluorescence cell imaging indicated considerable intercellular heterogeneity in biosensor-expression. However, FRET-measurements confirmed that these differences in expression levels have no effect on fractional zinc-saturation of the probe.

Immune response induced by major environmental pollutants through altering neutrophils in zebrafish larvae

Environmental pollutants may cause adverse effects on the immune system of aquatic organisms. However, the cellular effects of pollutants on fish immune system are largely unknown. Here, we exploited the transgenic zebrafish Tg(lysC:DsRed2) larva as a preliminary screening system to evaluate the potential inflammatory effects of environmental pollutants. Tg(lysC:DsRED2) larvae aged 7-day-postfertilization (7 dpf) were treated with selected environmental chemicals for 24 h (24 h) and the number of neutrophils were quantified using both image analysis and fluorescence activated cell sorting (FACS). We found that the numbers of neutrophils in the Tg(lysC:DsRED2) larvae were significantly increased by most of the organic chemicals tested, including E2 (17β-estradiol), BPA (Bisphenol-A), NDEA (N-nitrosodiethylamine), 4-NP (4-Nitrophenol) and Lindane (γ-hexachlorocyclohexane). Neutrophil numbers were also increased by all the metals tested (Na2HAsO4· 7H2O, Pb(NO3)2, HgCl₂, CdCl2, CuSO₄·5H₂O, ZnSO4, and K2Cr2O7). The only exception was TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), which significantly reduced the number of neutrophils after exposure. Additionally, the transcription of genes (lyz, mpo, tnfα and il8) related to fish immune system were significantly modulated upon exposure to some of the selected chemicals such as E2, TCDD, Cu and Cd. This study revealed that representatives of major categories of environmental pollutants could cause an acute inflammatory response in zebrafish larvae as shown by alterations in the neutrophils, which may imply a common immunotoxicity mechanism for most environmental pollutants. This study has also demonstrated that Tg(lyz:DsRed2) transgenic zebrafish is an excellent tool for screening environmental chemicals with potential inflammatory effects through FACS-facilitated neutrophil counting.

Zinc and Sepsis

Sepsis, defined as a “life-threatening organ dysfunction caused by a dysregulated host-response to infection” is a major health issue worldwide and still lacks a fully elucidated pathobiology and uniform diagnostic tests. The trace element zinc is known to be crucial to ensure an appropriate immune response. During sepsis a redistribution of zinc from serum into the liver has been observed and several studies imply a correlation between zinc and sepsis outcome. Therefore the alterations of zinc concentrations in different tissues might serve as one part of the host’s defense mechanism against pathogens during sepsis by diverse mechanisms. It has been suggested that zinc is involved in nutritional immunity, acts as a hepatoprotective agent, or a differentiation signal for innate immune cells, or supports the synthesis of acute phase proteins. Further knowledge about these events could help in the evaluation of how zinc could be optimally applied to improve treatment of septic patients. Moreover, the changes in zinc homeostasis are substantial and correlate with the severity of the disease, suggesting that zinc might also be useful as a diagnostic marker for evaluating the severity and predicting the outcome of sepsis.

Influencing the adhesion properties and wettability of mucin protein films by variation of the environmental pH

Mucins, the main component of the mucus secretions of goblet and epithelial cells, are known for exhibiting a different behaviour in accordance with their surrounding environment (i.e. among others the environmental pH), which induces a drastic change in their measured mechanical properties. In this work, we have first employed Atomic Force Microscopy (AFM) in Force Spectroscopy mode to evaluate the adhesion of porcine mucin films at the nanoscale, and the changes caused in this particular factor by a pH variation between 7.0 and 4.0, both quite common values in biological conditions. Measurements also involved additional varying factors such as the indenting tip chemistry (hydrophobic vs hydrophilic), its residence time on the measured film (0, 1 and/or 2 seconds), and increasing pulling rates (ranging from 0.1 up to 10 µm/s). A second approach regarded the macroscale behaviour of the films, due to their potential applicability in the development of a new set of stimuli-responsive biomaterials. This was possible by means of complementary Wilhelmy plate method (to test the wetting properties) and cell proliferation studies on films previously exposed to the corresponding pH solution. According to our results, treatment with lowest pH (4.0) provides porcine mucin with a more hydrophilic character, showing a much stronger adhesion for analogous chemistries, as well as enhanced capability for cell attachment and proliferation, which opens new pathways for their future use and consideration as scaffold-forming material.

Zinc Metabolism and Metallothioneins

Among the trace elements, zinc is one of the most used elements in biological systems. Zinc is found in the structure of more than 2700 enzymes, including hydrolases, transferases, oxyreductases, ligases, isomerases, and lyases. Not surprisingly, it is present in almost all body cells. Preserving the stability and integrity of biological membranes and ion channels, zinc is also an intracellular regulator and provides structural support to proteins during molecular interactions. It acts as a structural element in nucleic acids or other gene-regulating proteins. Metallothioneins, the low molecular weight protein family rich in cysteine groups, are involved significantly in numerous physiological and pathological processes including particularly oxidative stress. A critical role of metallothioneins (MT) is to bind zinc with high affinity and to serve as an intracellular zinc reservoir. By releasing free intracellular zinc when needed, MTs mediate the unique physiological roles of zinc. MT expression is induced by zinc elevation, and thus, zinc homeostasis is maintained. That MT mediates the effects of zinc, besides having strong radical scavenging effects, points to the critical part it plays in oxidative stress. The present review aims to give information on metallothioneins, which have critical importance in the metabolism and molecular pathways of zinc.

Zinc Protects Articular Chondrocytes through Changes in Nrf2-Mediated Antioxidants, Cytokines and Matrix Metalloproteinases

Osteoarthritis (OA) is an age-related degenerative joint disease characterized by high oxidative stress, chondrocyte death and cartilage damage. Zinc has been implicated in the antioxidant capacity of the cell, and its deficiency might inhibit chondrocyte proliferation. The present study examined the potential of zinc as a preventive supplement against OA using the in vitro chondrosarcoma cell line SW1353 and an in vivo Wistar rat model to mimic OA progress induced by monosodium iodoacetate (MIA). The results demonstrated that, in SW1353 cells, 5 μM MIA exposure increased oxidative stress and decreased the expression of GPx1 and Mn-SOD but still increased GSH levels and HO-1 expression and enhanced the expression of interleukin (IL)-10, IL-1β, and matrix metalloproteinase (MMP)-13. Zinc addition could block these changes. Besides, the expression of Nrf2 and phosphorylated (p)-Akt was dramatically increased, implicating the p-Akt/Nrf2 pathway in the effects of zinc on MIA-treated cells. A rat model achieved similar results as those of cell culture, and 1.6 mg/kg/day of zinc supplementation is sufficient to prevent OA progress, while 8.0 mg/kg/day of zinc supplementation does not have a better effect. These findings indicate that zinc supplementation exerts a preventive effect with respect to MIA-induced OA progress.

Trace elements concentrations in squids consumed in Shandong Province China and their associated risks to the human health

Determination of ten metal levels in 160 squid samples caught from offshore and the oceanic fishing locations by ICP-MS was made. The mean metal concentration in the squid muscles decreasing in the order of: Zn, Fe, Cu, As, Mn, Se, Cd, Pb, Cr and Ni. Metal concentrations in the squids were assessed for human uses according to provisional tolerable weekly intake (PTWI) and provisional tolerable daily intake (PTDI)·The estimated hazard quotients for the individual metals from squids were found in accordance to the following sequence: As > Cd > Cu > Se > Cr > Zn > Pb > Fe > Mn > Ni, with the greatest hazard upon human health coming primarily from As (1.34 < HQ < 1.73 in the Loliginidae from two offshore sampling sites and the Humboldt squid from the eastern Pacific Ocean). In regards to the heavy metal pollution of the coastal sea areas, the squids captured from offshore sites might pose a higher potential health risk to consumers compared to those from the ocean.

Microwave-assisted biosynthesis of zinc nanoparticles and their cytotoxic and antioxidant activity

The present study was designed for microwave assisted synthesis of zinc nanoparticles (Zn NPs) using Lavandula vera leaf extract in the presence of ZnSO₄ (1mM). The biogenic Zn NPs were then characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR) techniques. Thereafter, the cytotoxic effect of ZnSO₄ and Zn NPs on different cell lines was investigated by MTT-based cytotoxicity assay and their antioxidant properties were assessed using DPPH scavenging activity and reducing power assay. The SEM micrograph showed that the Zn NPs had spherical shape with the size range of 30-80nm. For A549, MCF-7, HT-29, and Caco-2 cell lines treated with Zn NPs, the concentration necessary causing 50% cell death (IC₅₀) was found to be 22.3±1.1μgmL^-1, 86±3.7μgmL^-1, 10.9±0.5μgmL^-1, and 56.2±2.8μgmL^-1, respectively. In the case of ZnSO₄, the same results (IC₅₀) were observed at concentration of 81.6±1.3μgmL^-1 (A549), 121.0±2.4μgmL^-1 (MCF-7), 43.0±1.4μgmL^-1 (HT-29), and 85.7±2.3μgmL^-1 (Caco-2). The obtained results of antioxidant activity showed that the IC₅₀ values of butylated hydroxyanisole (BHA) and Zn NPs were 44μgmL^-1and 65.3μgmL^-1, respectively, while ZnSO₄ at concentration of 200μgmL^-1 exhibited only 10.9% DPPH radical scavenging effect. Moreover, the reducing power of Zn NPs and BHA were significantly higher than ZnSO₄ (p<0.05). To sum up, application of L. vera leaf extract combined with microwave heating energy led to simple and fast formation of Zn nanostructures exhibited higher antioxidant and cytotoxic activity compared to soluble Zn⁺² ions. However, identification of the related mechanisms merit further studies.

The Hidden Function of Vitamin D

AIM:

There are no reports regarding the influence of vitamin D on thymosin ß4 and the cluster of differentiation CD4 levels which are important for maintaining a healthy immune system. Consequently, we aimed to explore this relationship through a study.

MATERIAL AND METHODS:

The study was carried out on 35 subjects, screened for 25-hydroxy vitamin D[25 (OH) D] using ELISA method and they were divided into two groups: Group 1 consists of 10 healthy subjects with sufficient vit. D level > 24.8 ng/ml. Group 2 consists of 25 subjects suffering, severely, from vitamin D deficiency at level < 11.325 ng/ml. Also, Thymosin ß4, CD4 and zinc levels were performed.

RESULTS:

There were significant differences between the two groups in the concentration levels of thymosin β4, as the group 1 has shown higher levels (P = 0.005). Whereas, CD4 and zinc levels didn’t show any significant difference between the two groups. At the same time, a significant positive correlation has been observed between vitamin D, thymosin β4, and CD4 at (r = 0.719; P = 0.001), and (r = 0.559, P = 0.001) respectively.

CONCLUSION:

We concluded that vitamin D may be an essential factor that influence or determine the level of thymosin β4. This study is the first that focused on demonstrating that sufficient level of vitamin D may have the ability to influence the thymic hormone thymosin β4 levels. Further studies on large scale of subjects are needed to explore the positive correlation we had found between vitamin D and thymosin β4 and CD4.

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.