Decreased expression of CD73 (ecto-5'-nucleotidase) in the CD8+ subset is associated with zinc deficiency in human patients

Impact of zinc on immunometabolism and its putative role on respiratory diseases

Zinc is the second most abundant trace mineral in the human body and plays a critical role in immune cell function and metabolism. Zinc deficiency impairs immune cell function and is associated with increased susceptibility to respiratory diseases, including pneumonia, influenza, and COVID-19. Zinc homeostasis, maintained by numerous zinc transporters and metal-binding proteins (ie, metallothionein), is essential for coordinating immune cell signaling, gene expression, and enzymatic activities in response to respiratory infections. This article highlights the emerging role of zinc in various aspects of immune function, particularly through its influence on cellular metabolism. Given the significant global burden of respiratory diseases, there is a need to identify effective nutritional interventions that could be readily leveraged to prevent and/or mitigate respiratory disease risk, particularly in older adults who are prone to zinc deficiency. However, the immunometabolic mechanisms underlying zinc's protective effects remain poorly characterized. Future research should focus on elucidating how micronutrients, such as zinc, can support changes in immune cell metabolism in response to infections. Such efforts will help determine how zinc metabolism and zinc intervention strategies may best be leveraged to prevent or mitigate respiratory disease.

A systematic review of the association between zinc and anxiety

CONTEXT

The incidence of anxiety, which stems from both intrinsic and extrinsic factors, has been increasing worldwide. Various methods by which it can be treated or prevented have been reported thus far. One of the most popular and effective treatments is supplementation therapy. Zinc, which is an essential nutrient found in various plants, animal foods, and supplements, has been shown to be a potential nutrient in anxiety reduction by acting on γ-aminobutyric acid (GABA), glutamatergic, serotonergic, neurogenesis, and immune systems. It can also influence important receptors, such as GPR39. Thus, zinc has received considerable attention with respect to its potential role as a therapeutic or detrimental factor for anxiety; yet, the available evidence needs to be analyzed systematically to reach a convergent conclusion.

OBJECTIVE

The objective was to systematically review any potential connection between adult human anxiety and zinc intake.

DATA SOURCES AND EXTRACTION

Nine original human studies, of which 2 assessed the relationship between zinc consumption and anxiety (based on a questionnaire) and 7 assessed the relationship between serum zinc levels and anxiety, were included based on specific selection criteria. Studies that had been written in English and published in peer-reviewed publications with no restrictions on the date of publication were searched in the Google Scholar and PubMed databases. This project was also reported according to the PRISMA guidelines.

DATA ANALYSIS

As per the studies analyzed in this review, there was a noticeable relationship between serum zinc levels and anxiety, which means that patients with anxiety have lower levels of zinc in their serum, as compared with healthy individuals. Furthermore, zinc consumption was inversely associated with anxiety.

CONCLUSION

The results provide plausible evidence for the positive role of zinc in the treatment of patients afflicted with anxiety, albeit with some limitations.

Clinically proven natural products, vitamins and mineral in boosting up immunity: A comprehensive review

BACKGROUND

and Purposes: The terminology "immune boost-up" was the talk of the topic in this Covid-19 pandemic. A significant number of the people took initiative to increase the body's defense capacity through boosting up immunity worldwide. Considering this, the study was designed to explain the natural products, vitamins and mineral that were proved by clinical trail as immunity enhancer.

METHODS

Information was retrieved from SciVerse Scopus ® (Elsevier Properties S. A, USA), Web of Science® (Thomson Reuters, USA), and PubMed based on immunity, nutrients, natural products in boosting up immunity, minerals and vitamins in boosting up immunity, and immune booster agents.

RESULT

A well-defined immune cells response provide a-well functioning defense system for the human physiological system. Cells of the immune system must require adequate stimulation so that these cells can prepare themselves competent enough to fight against any unintended onslaught. Several pharmacologically active medicinal plants and plants derived probiotics or micronutrients have played a pivotal role in enhancing the immune boost-up process. Their role has been well established from the previous study. Immune stimulating cells, especially cells of acquired immunity are closely associated with the immune-boosting up process because all the immunological reactions and mechanisms are mediated through these cells.

CONCLUSION

This article highlighted the mechanism of action of different natural products, vitamins and mineral in boosting up the immunity of the human body and strengthening the body's defense system. Therefore, it is recommended that until the specific immune-boosting drugs are available in pharma markets, anyone can consider the mentioned products as dietary supplements to boost up the immunity.

The Mechanisms of Zinc Action as a Potent Anti-Viral Agent: The Clinical Therapeutic Implication in COVID-19

The pandemic of COVID-19 was caused by a novel coronavirus termed as SARS-CoV2 and is still ongoing with high morbidity and mortality rates in the whole world. The pathogenesis of COVID-19 is highly linked with over-active immune and inflammatory responses, leading to activated cytokine storm, which contribute to ARDS with worsen outcome. Currently, there is no effective therapeutic drug for the treatment of COVID-19. Zinc is known to act as an immune modulator, which plays an important role in immune defense system. Recently, zinc has been widely considered as an anti-inflammatory and anti-oxidant agent. Accumulating numbers of studies have revealed that zinc plays an important role in antiviral immunity in several viral infections. Several early clinical trials clearly indicate that zinc treatment remarkably decreased the severity of the upper respiratory infection of rhinovirus in humans. Currently, zinc has been used for the therapeutic intervention of COVID-19 in many different clinical trials. Several clinical studies reveal that zinc treatment using a combination of HCQ and zinc pronouncedly reduced symptom score and the rates of hospital admission and mortality in COVID-19 patients. These data support that zinc might act as an anti-viral agent in the addition to its anti-inflammatory and anti-oxidant properties for the adjuvant therapeutic intervention of COVID-19.

Long COVID-19 in Children: From the Pathogenesis to the Biologically Plausible Roots of the Syndrome

Long Coronavirus disease-19 (COVID-19) refers to the persistence of symptoms related to the infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). This condition is described as persistent and can manifest in various combinations of signs and symptoms, such as fatigue, headache, dyspnea, depression, cognitive impairment, and altered perception of smells and tastes. Long COVID-19 may be due to long-term damage to different organs-such as lung, brain, kidney, and heart-caused by persisting viral-induced inflammation, immune dysregulation, autoimmunity, diffuse endothelial damage, and micro thrombosis. In this review, we discuss the potential and biologically plausible role of some vitamins, essential elements, and functional foods based on the hypothesis that an individual's dietary status may play an important adjunctive role in protective immunity against COVID-19 and possibly against its long-term consequences.

Serum zinc levels in pediatric patients with COVID-19

Zinc has potent immunoregulatory and antiviral effects that are critical for growth, immunity, and neurologic development. The aim of this study was to determine the clinical significance of serum zinc levels in pediatric patients with COVID-19 and to demonstrate its association with disease severity. This prospective observational study was conducted between August 3 and November 15, 2020, in pediatric patients aged 1 month to 18 years with confirmed COVID-19 using reverse transcription-polymerase chain reaction. We defined a control group whose serum zinc levels were determined 1 year ago at the same time as those of patients with COVID-19. We used 70 μg/dL as the cut-off zinc value to define zinc deficiency. Statistical analyses were performed using the SPSS for Windows statistics package program. One hundred children with confirmed COVID-19 and 269 children in the control group participated in the study. The median age was 13.3 (IQR: 8-15.4) years in patients with confirmed COVID-19, 11 patients had low serum zinc levels, and 89 patients had normal serum zinc levels. Patients in the group with low zinc levels had a significantly higher hospitalization rate than the group with normal zinc levels (5 (45.5%) and 10 patients (11.2%), respectively) (p = 0.011). The median serum zinc level in patients with COVID-19 was 88.5 mcg/dL (IQR 77.2-100), which was significantly lower than the median level in the control group, which was 98 mcg/dL (IQR 84-111) (p = 0.001). There was no association between the severity of COVID-19 and the serum zinc levels of the children.

CONCLUSION

Serum zinc levels may be influenced by many factors such as fasting status, diurnal variation, exercise, and sex, and may give an impression of the zinc status of the population rather than reflecting the individual. The fact that the incidence of hospitalization was significantly higher in patients with both COVID-19 and low serum zinc levels suggests that these patients require a detailed assessment of their living environment.

WHAT IS KNOWN

• Serum zinc levels have been found to be low in adult patients diagnosed with COVID-19. • There was a correlation between the severity of COVID-19 and serum zinc levels in adults.

WHAT IS NEW

• Children with low serum zinc levels were found to have a higher number of hospitalizations. • No association was found between the severity of COVID-19 disease and serum zinc levels in children.

Ionic Regulation of T-Cell Function and Anti-Tumour Immunity

The capacity of T cells to identify and kill cancer cells has become a central pillar of immune-based cancer therapies. However, T cells are characterized by a dysfunctional state in most tumours. A major obstacle for proper T-cell function is the metabolic constraints posed by the tumour microenvironment (TME). In the TME, T cells compete with cancer cells for macronutrients (sugar, proteins, and lipid) and micronutrients (vitamins and minerals/ions). While the role of macronutrients in T-cell activation and function is well characterized, the contribution of micronutrients and especially ions in anti-tumour T-cell activities is still under investigation. Notably, ions are important for most of the signalling pathways regulating T-cell anti-tumour function. In this review, we discuss the role of six biologically relevant ions in T-cell function and in anti-tumour immunity, elucidating potential strategies to adopt to improve immunotherapy via modulation of ion metabolism.

Levels of Zinc Transporters mRNA Depending on Zinc Status and HIV-1 Tat Induced Inflammation in Muscle (Rhabdomyosarcoma) and Monocyte (THP-1) Cell Lines

Monocytes and muscles demonstrate functionally contrasting behavior under conditions of zinc deficiency with relation to zinc storage system (muscle retain zinc in contrast to monocytes). We aimed to understand the effects of zinc status and HIV-1 Tat mediated inflammation on expression of zinc transporters in these types of cells. Expression of zinc transporters [ZnTs, ZIPs, and metallothionein (MT)] was quantified by qRT-PCR in RD, THP-1 cells separately and in co-cultured THP-1-RD cells. ZnT1 protein expression levels were confirmed by Western blot. Significant increase of MT and ZnT1 mRNA in response to zinc supplementation and decrease during zinc deficiency indicates significance of the genes encoding transporters in maintaining zinc homeostasis in these tissues. In the RD cells ZIP10 exhibited inverse relation to zinc status whereas no correlation was found in the THP-1 cells. Tat-induced inflammation resulted in the significant elevation of MT, IL6, ZIP7, ZIP8, ZIP9 transcripts in the co-cultured RD cells, whereas THP-1 cells demonstrated increased IL-1β levels and reduced levels of ZIP7 and ZIP14. Zinc status and HIV-1Tat induced inflammation appear to influence differential expression of MT, ZnTs, and ZIPs in the muscle and monocyte cells.

High level of CD73 predicts poor prognosis of intrahepatic cholangiocarcinoma

Background: Despite recent improvements in the diagnosis and therapy of intrahepatic cholangiocarcinoma (ICC), the prognosis for ICC patients remains poor. Therefore, it is needed to identify new biological indicators for ICC progression.

Methods: Immunohistochemistry was engaged to inspect the ecto-5ʹ-nucleotidase (CD73) and CD8 expressions in tissue microarrays including tissues from 140 ICC patients. Then, the association between the level of CD73/CD8 and clinicopathologic characteristics of ICC was analysed. Finally, the prognostic value of CD73 and CD8 levels in ICC patients was assessed by Kaplan-Meier and multivariate and univariate analyses.

Results: The CD73 expression was evidently upregulated in ICC tissues compared to the corresponding peritumoral tissues. The elevated CD73 expression was positively related to the lymphatic metastasis (p=0.049). While the level of tumour-infiltrating CD8 T⁺ cells in tumour tissues was negatively associated with serum AFP (p=0.019), tumor size (p=0.028), and lymphatic metastasis (p=0.039). Additionally, patients with elevated CD73 expression or low tumour-infiltrating CD8⁺ T cells exhibited shorter overall survival (OS) and higher disease-free survival (DFS) rates than patients with low CD73 expression and/or high tumour-infiltrating CD8⁺ T cells. Notably, the overexpression of CD73 or low tumour-infiltrating CD8⁺ T cells was an independent indicator for predicting the OS and DFS of ICC patients.

Conclusions: We revealed that CD73 expression and low tumour-infiltrating CD8⁺T cells are valuable predictors of survival and recurrence in patients with ICC.

Conditional nutrition (I): concerning zinc as a beneficial but variable regulator of inflammation and experimental arthritis

This article extends the concept of conditional pharmacology (Whitehouse and Vernon-Roberts 1991; Whitehouse 1995) that considers how both internal factors/disease and external/environmental factors may alter the availability or efficacy of exogenous drugs. The same and other conditioning factors may also affect the utility and value of many nutriceuticals that may be clearly beneficial in the context of inflammation but sometimes showing quite variable pharmaco-activity. This is illustrated by considering some factors affecting the bioavailability and pharmaco-efficacy of dietary ionic zinc, Zn (II) an essential trace metal and a critical regulator of inflammation and tissue repair. With chronic zinc deficiency (zincopenia) due to diet, drugs and/or disease, we can usually survive-but may not necessarily thrive. Some strategies to minimise zincopenia are considered, based upon finding efficient means for (1) preventing its cause and/or (2) using parenteral delivery of zinc supplements to circumvent dietary and enteric impediments to zinc bio-availability.

The Role of Micronutrients in the Infection and Subsequent Response to Hepatitis C Virus

Micronutrient deficiencies develop for a variety of reasons, whether geographic, socioeconomic, nutritional, or as a result of disease pathologies such as chronic viral infection. As micronutrients are essential for a strong immune response, deficiencies can significantly dampen both the innate and the adaptive arms of antiviral immunity. The innate immune response in particular is crucial to protect against hepatitis C virus (HCV), a hepatotropic virus that maintains chronic infection in up to 80% of individuals if left untreated. While many micronutrients are required for HCV replication, an overlapping group of micronutrients are also necessary to enact a potent immune response. As the liver is responsible for the storage and metabolism of many micronutrients, HCV persistence can influence the micronutrients' steady state to benefit viral persistence both directly and by weakening the antiviral response. This review will focus on common micronutrients such as zinc, iron, copper, selenium, vitamin A, vitamin B12, vitamin D and vitamin E. We will explore their role in the pathogenesis of HCV infection and in the response to antiviral therapy. While chronic hepatitis C virus infection drives deficiencies in micronutrients such as zinc, selenium, vitamin A and B12, it also stimulates copper and iron excess; these micronutrients influence antioxidant, inflammatory and immune responses to HCV.

Molecular Mechanisms of Zinc as a Pro-Antioxidant Mediator: Clinical Therapeutic Implications

The essentiality of zinc as a trace mineral in human health has been recognized for over five decades. Zinc deficiency, caused by diet, genetic defects, or diseases, can cause growth retardation, delayed sexual maturation, depressed immune response, and abnormal cognitive functions in humans. Zinc supplementation in zinc-deficient individuals can overcome or attenuate these abnormalities, suggesting zinc is an essential micro-nutrient in the body. A large number of in vitro and in vivo experimental studies indicate that zinc deficiency also causes apoptosis, cellular dysfunction, deoxyribonucleic acid (DNA) damage, and depressed immune response. Oxidative stress, due to the imbalance of reactive oxygen species (ROS) production and detoxification in the anti-oxidant defense system of the body, along with subsequent chronic inflammation, is believed to be associated with many chronic degenerative diseases such as diabetes, heart diseases, cancers, alcohol-related disease, macular degenerative disease, and neuro-pathogenesis. A large number of experimental studies including cell culture, animal, and human clinical studies have provided supportive evidence showing that zinc acts as an anti-oxidative stress agent by inhibition of oxidation of macro-molecules such as (DNA)/ribonucleic acid (RNA) and proteins as well as inhibition of inflammatory response, eventually resulting in the down-regulation of (ROS) production and the improvement of human health. In this article, we will discuss the molecular mechanisms of zinc as an anti-oxidative stress agent or mediator in the body. We will also discuss the applications of zinc supplementation as an anti-oxidative stress agent or mediator in human health and disease.

A Novel Specific Anti-CD73 Antibody Inhibits Triple-Negative Breast Cancer Cell Motility by Regulating Autophagy

Increasing researches have focused on cancer metastasis and development. The ectonucleotidase CD73 is one of the most common cell surface enzymes that are involved in immunosuppression. In this study, the recombinant plasmid pET28a-CD73 was constructed and the CD73 protein was overexpressed in E. coli as an inclusion body that was then subjected to refolding. The anti-CD73 monoclonal antibody (3F7) was obtained by hybridoma technology. The antibody subtype was identified as IgG2a with an affinity constant of 5.75 nM. This antibody could be applied to immunofluorescence and flow cytometry. The results showed that the CD73 protein was not only located in the cytoplasm but also distributed on the surface of triple-negative breast cancer cells MDA-MB-231 and MDA-MB-468. Moreover, the level of CD73 protein was associated with the survival rate. Although the anti-CD73 antibody was not able to inhibit tumor cell growth, it could enhance the cytotoxic effect of Doxorubicin to triple-negative breast cancer cells. In vitro function assay results indicated that anti-CD73 mAb could inhibit cell migration and invasion in both human triple-negative breast cancer and mouse 4T1 cell lines. In this process, both the LC3I/LC3II ratio and p62 protein levels increased, which indicated that the blockage of CD73 could inhibit cell autophagy, and cell migration and invasion were restored by rapamycin. In vivo, anti-CD73 mAb could significantly inhibit lung metastasis of 4T1 cells in a mouse xenograft model. Taken together, this novel anti-CD73 antibody could be developed as an adjuvant drug for triple-negative breast cancer therapy and can be useful in tumor diagnosis.

Metallothionein: a Potential Link in the Regulation of Zinc in Nutritional Immunity

Nutritional immunity describes mechanisms for withholding essential transition metals as well as directing the toxicity of these metals against infectious agents. Zinc is one of these transition elements that are essential for both humans and microbial pathogens. At the same time, Zn can be toxic both for man and microbes if its concentration is higher than the tolerance limit. Therefore a "delicate" balance of Zn must be maintained to keep the immune cells surveilling while making the level of Zn either to starve or to intoxicate the pathogens. On the other hand, the invading pathogens will exploit the host Zn pool for its survival and replication. Apparently, different sets of protein in human and bacteria are involved to maintain their Zn need. Metallothionein (MT)-a group of low molecular weight proteins, is well known for its Zn-binding ability and is expected to play an important role in that Zn balance at the time of active infection. However, the differences in structural, functional, and molecular control of biosynthesis between human and bacterial MT might play an important role to determine the proper use of Zn and the winning side. The current review explains the possible involvement of human and bacterial MT at the time of infection to control and exploit Zn for their need.

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.

Discovery of Zinc for Human Health and Biomarkers of Zinc Deficiency

Zinc deficiency in humans was recognized for the first time in 1963, and a recommended dietary allowance (RDA) for zinc was established by the US National Academy of Sciences in 1974. The present World Health Organization (WHO) estimate is that nearly 2 billion subjects living in the developing world may have zinc deficiency. This is mainly because they subsist on cereal proteins which contain high quantities of organic phosphate compounds, which combine with zinc making it unavailable for absorption. The major adverse clinical effects of zinc deficiency are growth retardation, decreased cell-mediated immunity, impairment of cognitive functions, increased oxidative stress, and upregulation of inflammatory cytokines. Our studies have shown that nearly 30% of healthy, well-to-do elderly subjects living in developed countries may also be zinc deficient due to an increased phytate to zinc molar ratio in their diet. Over 300 enzymes and 2000 transcription factors are now known to require zinc for their functions and stability of their structures, and several studies have now shown that zinc may be a molecular signal for neuronal and immune cells. Fourteen ZIP and 10 ZNT zinc transporters are known to maintain intracellular zinc homeostasis. Therapeutic impacts of zinc on human health are also being investigated. Zinc is being used for the treatment of acute diarrhea in infants and children in developing countries globally, and this has resulted in saving millions of lives. Zinc is now an approved drug for the treatment and maintenance therapy of Wilson's disease, a serious fatal genetic disorder. According to a recent Cochrane Review, zinc is the only treatment which is effective in decreasing the incidence of infections and pain crises in patients with sickle cell disease. Zinc acetate lozenges have been shown to decrease the duration of the common cold by 50%, provided the treatment is started within 24 h of the onset of symptoms, the solution chemistry of the zinc preparation is proper, and the zinc dosages are adequate. Age-related macular degeneration (AMD) accounts for a large proportion of legal blindness in elderly subjects throughout the world. The Age-Related Eye Disease Study Group (AREDS) was supported by National Eye Institute. The National Institutes of Health (NIH) has now reported the results of their 10-year zinc supplementation study in patients with AMD. Zinc was effective in decreasing the incidences of blindness and progression of AMD in elderly subjects. Most importantly, zinc-supplemented subjects showed increased longevity and this was due to a decrease in cardiovascular events. No other micronutrient has shown this dramatic effect on decreasing mortality in the elderly. Our placebo-controlled, zinc supplementation trial in the elderly has shown that zinc supplementation decreased the incidence of infections by 66% and improved cell-mediated immunity. Also, we showed that oxidative stress markers and gene expression of inflammatory cytokines were decreased in elderly subjects who received zinc supplementation. These studies suggest that zinc supplementation in the elderly may have a preventive role in atherosclerosis. Plasma zinc is widely used as a biomarker of zinc deficiency in humans. This test is, however, neither specific nor sensitive. Assays of immunological markers such as plasma active thymulin and gene expression of IL-2 in PHA-stimulated lymphocytes are very sensitive and specific for the diagnosis of human zinc deficiency. The assay of zinc in cells such as lymphocytes and granulocytes are better than plasma zinc; however, even these assays are less sensitive than immunological biomarkers.

Effect of zinc supplementation on serum zinc concentration and T cell proliferation in nursing home elderly: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Zinc is essential for the regulation of immune response. T cell function declines with age. Zinc supplementation has the potential to improve the serum zinc concentrations and immunity of nursing home elderly with a low serum zinc concentration.

OBJECTIVE

We aimed to determine the effect of supplementation with 30 mg Zn/d for 3 mo on serum zinc concentrations of zinc-deficient nursing home elderly.

DESIGN

This was a randomized, double-blind, placebo-controlled study. Of 53 nursing home elderly (aged ≥65 y) who met eligibility criteria, 58% had a low serum zinc concentration (serum zinc <70 μg/dL); these 31 were randomly assigned to zinc (30 mg Zn/d) (n = 16) or placebo (5 mg Zn/d) (n = 15) groups. The primary outcome measure was change in serum zinc concentrations between baseline and month 3. We also explored the effects of supplementation on immune response.

RESULTS

Baseline characteristics were similar in the 2 groups. The difference in the mean change in serum zinc was significantly higher, by 16%, in the zinc group than in the placebo group (P = 0.007) when baseline zinc concentrations were controlled for. In addition, controlling for baseline C-reactive protein, copper, or albumin did not change the results. However, supplementation of participants with ≤60 μg serum Zn/dL failed to increase their serum zinc to ≥70 μg/dL. Zinc supplementation also significantly increased anti-CD3/CD28 and phytohemagglutinin-stimulated T cell proliferation, and the number of peripheral T cells (P < 0.05). When proliferation was expressed per number of T cells, the significant differences between groups were lost, suggesting that the zinc-induced enhancement of T cell proliferation was mainly due to an increase in the number of T cells.

CONCLUSIONS

Zinc supplementation at 30 mg/d for 3 mo is effective in increasing serum zinc concentrations in nursing home elderly; however, not all zinc-deficient elderly reached adequate concentrations. The increase in serum zinc concentration was associated with the enhancement of T cell function mainly because of an increase in the number of T cells.

Prognostic value of blood zinc, iron, and copper levels in critically ill children with pediatric risk of mortality score III

We aimed to explore the association of blood Zn, Fe, and Cu concentrations and changes in the pediatric risk of mortality (PRISM) score in critically ill children, to predict prognosis. We included 31 children (22 boys and 9 girls, 1 month to 5 years old), who had been admitted to the intensive care unit of our hospital and who were critically ill according to PRISM score of III. Another 20 children (12 boys, 8 girls, 3 months to 5 years old) who were brought to the hospital for a health checkup were included as controls. We recorded clinical data, time in the intensive care unit, prognosis, and PRISM III score for critically ill children. Blood Cu, Zn, and Fe values were measured by inductively coupled plasma atomic emission spectrophotometry. Zn and Fe levels were significantly lower in patients than in controls (all p < 0.05). Cu levels differed between patients and controls, but not significantly (p > 0.05). In ill children, blood Zn and Fe concentrations were inversely correlated with PRISM III score (Zn: r = -0.36; Fe: r = -0.50, both p < 0.05), with no significant correlation of blood Cu level and PRISM III score (r = -0.13, p > 0.05). Serious illness in children may lead to decreased Zn and Fe blood concentrations. Zn and Fe supplements may be beneficial for critically ill children.

Discovery of human zinc deficiency: its impact on human health and disease

The essentiality of zinc in humans was established in 1963. During the past 50 y, tremendous advances in both clinical and basic sciences of zinc metabolism in humans have been observed. The major factor contributing to zinc deficiency is high phytate-containing cereal protein intake in the developing world, and nearly 2 billion subjects may be zinc deficient. Conditioned deficiency of zinc has been observed in patients with malabsorption syndrome, liver disease, chronic renal disease, sickle cell disease, and other chronic illnesses. Major clinical problems resulting from zinc deficiency in humans include growth retardation; cell-mediated immune dysfunction, and cognitive impairment. In the Middle East, zinc-deficient dwarfs did not live beyond the age of 25 y, and they died because of intercurrent infections. In 1963, we knew of only 3 enzymes that required zinc for their activities, but now we know of >300 enzymes and >1000 transcription factors that are known to require zinc for their activities. Zinc is a second messenger of immune cells, and intracellular free zinc in these cells participate in signaling events. Zinc has been very successfully used as a therapeutic modality for the management of acute diarrhea in children, Wilson's disease, the common cold and for the prevention of blindness in patients with age-related dry type of macular degeneration and is very effective in decreasing the incidence of infection in the elderly. Zinc not only modulates cell-mediated immunity but is also an antioxidant and anti-inflammatory agent.

Association of reduced zinc status with angiographically severe coronary atherosclerosis: a pilot study

In vitro studies attribute antiatherogenic and insulin-like properties to zinc (Zn). However, only a few conflicting clinical data exist concerning the relationship between Zn and coronary artery disease (CAD) as well as glycemic indices. We studied 72 patients without prior history of myocardial infarction or revascularization procedures, who underwent coronary angiography for evaluation of chest pain. Coronary artery disease severity was estimated using 3 angiographic scores. Zn in serum and 24-hour urine, as well as serum Zn/24-hour urine Zn ratio were determined. Serum Zn was not associated with CAD prevalence and severity. However, urinary Zn loss was significantly higher among patients with CAD and showed a positive association with CAD severity. Serum Zn/24-hour urine Zn ratio was inversely associated with CAD, as well as with diabetes mellitus prevalence, fasting glucose, and glycated hemoglobin levels. Low serum Zn/24-hour urine Zn ratio is associated with angiographically severe atherosclerosis and impaired glucose homeostasis.

Correlation of concentrations of selected trace elements with Gleason grade of prostate tissues

The causes of prostate cancer are still obscure but some evidence indicates that there is a close connection between several trace elements and processes which may lead to malignant cells. In our study the microbeam synchrotron radiation X-ray fluorescence emission (micro-SRIXE) technique was applied for quantitative analysis of selected elements. For the first time, we correlate the concentrations of Mn, Fe, Cu, and Zn with the clinical stage of the prostate cancer at the time of operation (described by Gleason grade). Serial sections of prostate tissues were collected from patients undergoing radical prostatectomy. One section, stained with hematoxylin and eosin, was prepared for histopathological analysis; a second, adjacent unstained section was used in micro-SRIXE experiments. All experiments were performed at beamline L at HASYLAB, DESY, Germany. Our results seem to be valuable in light of the determination of the changes in the concentrations of trace elements as a potential diagnostic marker and their etiological involvement in the different stages of prostate diseases.

Zinc deficiency

PURPOSE OF REVIEW

Zinc plays an essential role in numerous biochemical pathways. Zinc deficiency affects many organ systems, including the integumentary, gastrointestinal, central nervous system, immune, skeletal, and reproductive systems. This article aims to discuss zinc metabolism and highlights a few of the diseases associated with zinc deficiency.

RECENT FINDINGS

Zinc deficiency results in dysfunction of both humoral and cell-mediated immunity and increases the susceptibility to infection. Supplementation of zinc has been shown to reduce the incidence of infection as well as cellular damage from increased oxidative stress. Zinc deficiency is also associated with acute and chronic liver disease. Zinc supplementation protects against toxin-induced liver damage and is used as a therapy for hepatic encephalopathy in patients refractory to standard treatment. Zinc deficiency has also been implicated in diarrheal disease, and supplementation has been effective in both prophylaxis and treatment of acute diarrhea.

SUMMARY

This article is not meant to review all of the disease states associated with zinc deficiency. Rather, it is an introduction to the influence of the many roles of zinc in the body, with an extensive discussion of the influence of zinc deficiency in selected diseases. Zinc supplementation may be beneficial as an adjunct to treatment of many disease states.

Zinc in human health: effect of zinc on immune cells

Although the essentiality of zinc for plants and animals has been known for many decades, the essentiality of zinc for humans was recognized only 40 years ago in the Middle East. The zinc-deficient patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in an experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, hyperammonemia, neurosensory disorders, and decreased lean body mass. It appears that zinc deficiency is prevalent in the developing world and as many as two billion subjects may be growth retarded due to zinc deficiency. Besides growth retardation and immune dysfunctions, cognitive impairment due to zinc deficiency also has been reported recently. Our studies in the cell culture models showed that the activation of many zinc-dependent enzymes and transcription factors were adversely affected due to zinc deficiency. In HUT-78 (T helper 0 [Th(0)] cell line), we showed that a decrease in gene expression of interleukin-2 (IL-2) and IL-2 receptor alpha(IL-2Ralpha) were due to decreased activation of nuclear factor-kappaB (NF-kappaB) in zinc deficient cells. Decreased NF-kappaB activation in HUT-78 due to zinc deficiency was due to decreased binding of NF-kappaB to DNA, decreased level of NF-kappaB p105 (the precursor of NF-kappaB p50) mRNA, decreased kappaB inhibitory protein (IkappaB) phosphorylation, and decreased Ikappa kappa. These effects of zinc were cell specific. Zinc also is an antioxidant and has anti-inflammatory actions. The therapeutic roles of zinc in acute infantile diarrhea, acrodermatitis enteropathica, prevention of blindness in patients with age-related macular degeneration, and treatment of common cold with zinc have been reported. In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF pathway, decreases NF-kappaB activation, leading to decreased gene expression and generation of tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8. We have reported recently that in both young adults and elderly subjects, zinc supplementation decreased oxidative stress markers and generation of inflammatory cytokines.

Zinc in human health: effect of zinc on immune cells

Although the essentiality of zinc for plants and animals has been known for many decades, the essentiality of zinc for humans was recognized only 40 years ago in the Middle East. The zinc-deficient patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in an experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, hyperammonemia, neurosensory disorders, and decreased lean body mass. It appears that zinc deficiency is prevalent in the developing world and as many as two billion subjects may be growth retarded due to zinc deficiency. Besides growth retardation and immune dysfunctions, cognitive impairment due to zinc deficiency also has been reported recently. Our studies in the cell culture models showed that the activation of many zinc-dependent enzymes and transcription factors were adversely affected due to zinc deficiency. In HUT-78 (T helper 0 [Th(0)] cell line), we showed that a decrease in gene expression of interleukin-2 (IL-2) and IL-2 receptor alpha(IL-2Ralpha) were due to decreased activation of nuclear factor-kappaB (NF-kappaB) in zinc deficient cells. Decreased NF-kappaB activation in HUT-78 due to zinc deficiency was due to decreased binding of NF-kappaB to DNA, decreased level of NF-kappaB p105 (the precursor of NF-kappaB p50) mRNA, decreased kappaB inhibitory protein (IkappaB) phosphorylation, and decreased Ikappa kappa. These effects of zinc were cell specific. Zinc also is an antioxidant and has anti-inflammatory actions. The therapeutic roles of zinc in acute infantile diarrhea, acrodermatitis enteropathica, prevention of blindness in patients with age-related macular degeneration, and treatment of common cold with zinc have been reported. In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF pathway, decreases NF-kappaB activation, leading to decreased gene expression and generation of tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8. We have reported recently that in both young adults and elderly subjects, zinc supplementation decreased oxidative stress markers and generation of inflammatory cytokines.

Zinc supplementation decreases oxidative stress, incidence of infection, and generation of inflammatory cytokines in sickle cell disease patients

Zinc deficiency is common in adult sickle-cell disease (SCD) patients. We previously demonstrated that zinc supplementation to adult SCD patients decreased the incidences of infections and hospital admissions. We hypothesize that zinc supplementation improves T-helper cell function and decreases vascular endothelial cell activation, oxidative stress, and nuclear factor-kappa B (NF-kappaB)-DNA binding in mononuclear cells (MNCs) in SCD patients. To test this hypothesis, 36 SCD patients were recruited and randomly divided into 2 groups. One group (n = 18) received 25-mg zinc orally thrice a day for 3 months. The other group (n = 18) received placebo. The results indicate that the zinc-supplemented group had decreased incidence of infections compared with the placebo group. After zinc supplementation, red blood cell, hemoglobin (Hb), hematocrit, (Hct), plasma zinc, and antioxidant power increased; plasma nitrite and nitrate (NOx), lipid peroxidation products, DNA oxidation products, and soluble vascular cell adhesion molecule-1 decreased in the zinc-supplemented group, compared with the placebo group. Zinc-supplemented patients exhibited significant decreases in lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha) and IL-1beta mRNAs, and TNF-induced nuclear factor of kappaB-DNA binding in MNCs, compared with the placebo group. Ex vivo addition of zinc to MNCs isolated from the placebo subjects decreased TNF-alpha and IL-1beta mRNAs. Zinc supplementation also increased relative levels of IL-2 and IL-2Ralpha mRNAs in phytohemagglutinin-p-stimulated MNCs. These results suggest that zinc supplementation may be beneficial to SCD patients.

Clinical, immunological, anti-inflammatory and antioxidant roles of zinc

The essentiality of zinc for humans was recognized only 40 years ago. Zinc deficiency was suspected to occur in Iranian patients with growth retardation, hypogonadism in males, hepato-splenomegaly, rough and dry skin, geophagia and severe iron deficiency anemia. Later we documented zinc deficiency in similar patients in Egypt. The diet of these patients consisted of mainly cereal proteins which contained high phytate and this led to decreased availability of iron and zinc. These patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, decreased serum thymulin activity hyperammonemia, neuro-sensory disorders and decreased lean body mass. The basic mechanisms of zinc action on immune cells have been reviewed in this paper. Our studies showed that the activation of many zinc dependent enzymes and transcription factors were affected adversely due to zinc deficiency. The gene expression and production of Th1 cytokines were affected adversely due to zinc deficiency. Zinc is also an antioxidant and has anti-inflammatory actions. We have reported decreased plasma zinc, increased plasma oxidative stress markers and increased generation of inflammatory cytokines in the elderly subjects which were corrected by zinc supplementation. In cell culture studies, we have observed that zinc induces A20 which inhibits NF-kappaB activation resulting in decreased generation of inflammatory cytokines.

The heat shock proteins in cellular aging: is zinc the missing link?

T-cell functions are critical for the efficiency of the adaptive immune response. It is now clear that aging is associated with changes in the T-cell response to antigenic stimulation, one of the many changes collectively resulting in immune senescence. Several hypotheses have been proposed to explain such changes. We believe that chronic stimulation of T-cells enhances the appearance of apoptosis-resistant anergic dysfunctional cells; in humans in vivo these are predominantly specific for antigens of persistent viruses, especially CMV. Concomitantly, age-associated zinc deficiency is common and one hypothesis is that lack of zinc bioavailability contributes to impaired T-cell function. This could further compromise the integrity of T-cells under chronic antigenic stress, which can be modelled in long-term clonal cultures in vitro. Newly synthesized heat-shock proteins (HSPs) protect the cellular proteins from degradation under such conditions. In this short review we will briefly outline the role of heat-shock proteins and zinc deficiency in aging in order to finally discuss our own results in the context of a link between HSPs, aging and zinc.

NMDA receptor-mediated extracellular adenosine accumulation is blocked by phosphatase 1/2A inhibitors

We have previously demonstrated that NMDA receptor-mediated extracellular adenosine accumulation in neuronal cultures is receptor-mediated and requires calcium influx. Because protein kinase C (PKC) is a calcium-dependent enzyme, we hypothesized that activation of PKC might be involved in NMDA-mediated adenosine accumulation. PKC inhibitors, however, did not block NMDA-evoked adenosine accumulation, but rather, stimulated basal adenosine accumulation. These data suggested the possibility that NMDA receptor-mediated adenosine accumulation involves net dephosphorylation rather than phosphorylation of one or more substrates. Thus, inhibition of kinases would be expected to increase adenosine accumulation and inhibition of phosphatases would be expected to block adenosine accumulation. To test this hypothesis, we used the phosphatase 1/2A inhibitors calyculin A and okadaic acid. Both inhibitors significantly reduced NMDA-evoked adenosine accumulation. In contrast phosphatase 2B inhibitors did not block NMDA-evoked adenosine accumulation. These data suggest that NMDA-evoked adenosine accumulation is mediated by activation of phosphatase 1/2A. We have established previously that NMDA-mediated adenosine accumulation is associated with adenosine kinase inhibition. However, adenosine kinase is not a direct substrate for phosphatase 1/2A because inhibition of phosphatase 1/2A did not abolish NMDA-evoked adenosine kinase inhibition. Okadaic acid also had no effect on NO donor-evoked adenosine accumulation, which previously has been shown to be associated with adenosine kinase inhibition. Dephosphorylation of one or more proteins other than adenosine kinase as a consequence of NMDA receptor activation might play an important role in extracellular adenosine regulation, with important consequences for the regulation of excitatory synaptic transmission, plasticity, epileptogenesis, and excitotoxicity.

Zinc: mechanisms of host defense

Zinc deficiency in humans decreases the activity of serum thymulin (a thymic hormone), which is required for maturation of T-helper cells. T-helper 1 (Th(1)) cytokines are decreased but T-helper 2 (Th(2)) cytokines are not affected by zinc deficiency in humans. This shift of Th(1) to Th(2) function results in cell-mediated immune dysfunction. Because IL-2 production (Th(1) cytokine) is decreased, this leads to decreased activities of natural-killer cell and T cytolytic cells, which are involved in killing viruses, bacteria, and tumor cells. In humans, zinc deficiency may decrease the generation of new CD4+ T cells from the thymus. In cell culture studies (HUT-78, a Th(0) human malignant lymphoblastoid cell line), as a result of zinc deficiency, nuclear factor-kappaB (NF-kappaB) activation, phosphorylation of IkappaB, and binding of NF-kappaB to DNA are decreased and this results in decreased Th(1) cytokine production. In another study, zinc supplementation to humans decreased the gene expression and production of pro-inflammatory cytokines and decreased oxidative stress markers. In HL-60 cells (a human pro-myelocytic leukemia cell line), zinc deficiency increased the levels of TNF-alpha, IL-1beta, and IL-8 cytokines and mRNA. In these cells, zinc induced A20, a zinc finger protein that inhibited NF-kappaB activation via tumor necrosis factor receptor associated factor pathway, and this decreased gene expression of pro-inflammatory cytokines and oxidative stress markers. We conclude that zinc has an important role in cell-mediated immune functions and also functions as antiinflammatory and antioxidant agent.

Zinc requirements and the risks and benefits of zinc supplementation

The adult human contains 2-3g of zinc, about 0.1% of which are replenished daily. On this basis and based on estimates of bioavailability of zinc, dietary recommendations are made for apparently healthy individuals. Absent chemical, functional, and/or physical signs of zinc deficiency are assumed indicative of adequacy. More specific data are seldom available. Changing food preferences and availability, and new food preparation, preservation, and processing technologies may require re-evaluation of past data. Conservative estimates suggest that 25% of the world's population is at risk of zinc deficiency. Most of the affected are poor, and rarely consume foods rich in highly bioavailable zinc, while subsisting on foods that are rich in inhibitors of zinc absorption and/or contain relatively small amounts of bioavailable zinc. In contrast, among the relatively affluent, food choice is a major factor affecting risk of zinc deficiency. An additional problem, especially among the relatively affluent, is risk of chronic zinc toxicity caused by excessive consumption of zinc supplements. High intakes of zinc relative to copper can cause copper deficiency. A major challenge that has not been resolved for maximum health benefit is the proximity of the recommended dietary allowance (RDA) and the reference dose (RfD) for safe intake of zinc. Present recommendations do not consider the numerous dietary factors that influence the bioavailability of zinc and copper, and the likelihood of toxicity from zinc supplements. Thus the current assumed range between safe and unsafe intakes of zinc is relatively narrow. At present, assessment of zinc nutriture is complex, involving a number of chemical and functional measurements that have limitations in sensitivity and specificity. This approach needs to be enhanced so that zinc deficiency or excess can be detected early. An increasing number of associations between diseases and zinc status and apparently normal states of health, where additional zinc might be efficacious to prevent certain conditions, point at the pharmacology of zinc compounds as a promising area. For example, relationships between zinc and diabetes mellitus are an area where research might prove fruitful. In our opinion, a multidisciplinary approach will most likely result in success in this fertile area for translational research.

Importância do zinco na nutrição humana

Recentes pesquisas experimentais e clínicas têm reforçado a importância do zinco na saúde humana. O zinco possibilita várias funções bioquímicas, pois é componente de inúmeras enzimas, dentre estas, álcool desidrogenase, superóxido dismutase, anidrase carbônica, fosfatase alcalina e enzimas do sistema nervoso central. Participa na divisão celular, expressão genética, processos fisiológicos como crescimento e desenvolvimento, na transcrição genética, na morte celular, age como estabilizador de estruturas de membranas e componentes celulares, além de participar da função imune e desenvolvimento cognitivo. Sua deficiência pode causar alterações fisiológicas como, hipogonodismo, danos oxidativos, alterações do sistema imune, hipogeusia, danos neuropsicológicos e dermatites. Assim, devido a inúmeras pesquisas referentes a este mineral, este trabalho teve como objetivo mostrar os aspectos atuais sobre a essencialidade do zinco na nutrição humana.

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.

Serum zinc status in chronic hepatitis B and its relationship to liver histology and treatment results

BACKGROUND

It is known that cytotoxic T lymphocytes are responsible for viral clearance in chronic hepatitis B (HBV) infection. Zinc deficiency affects development of acquired immunity by preventing certain functions of T lymphocytes. We investigated the serum zinc levels and the relationship to liver histopathology and response to interferon alpha (IFN-alpha) and lamivudine combination therapy in 28 children with chronic HBV infection.

METHODS

A course of IFN-alpha was injected as 5 million U/m2 subcutaneously, thrice a week for 6 months and lamivudine 4 mg/kg per day orally, for 1 year. Normalization of alanine aminotransferase (ALT), loss of HBV DNA, hepatitis B e antigen (HBeAg) seroconversion altogether was considered as end of therapy response (ETR).

RESULTS

The ETR was achieved in eight (30.7%) patients. Serum zinc concentrations of 20 healthy children and patients was not significantly different (P>0.05). While pretreatment serum ALT, zinc, histological activity index (HAI) and portal inflammation scores were statistically higher in children who had ETR (P<0.005, P<0.05, P<0.05 and P<0.05, respectively), pretreatment serum HBV DNA was lower (P<0.005). Serum zinc level was correlated with HAI and portal inflammation scores (P<0.01 and P<0.01).

CONCLUSION

This study showed the relationship of serum zinc status to liver histopathology and to the ETR and may be a preliminary study leading new studies focusing on zinc status in patients with chronic HBV infection.

Effects of zinc deficiency on Th1 and Th2 cytokine shifts

Nutritional deficiency of zinc is widespread throughout developing countries, and zinc-deficient persons have increased susceptibility to a variety of pathogens. Zinc deficiency in an experimental human model caused an imbalance between Th1 and Th2 functions. Production of interferon-gamma and interleukin (IL)-2 (products of Th1) were decreased, whereas production of IL-4, IL-6, and IL-10 (products of Th2) were not affected during zinc deficiency. Zinc deficiency decreased natural killer cell lytic activity and percentage of precursors of cytolytic T cells. In HuT-78, a Th0 cell line, zinc deficiency decreased gene expression of thymidine kinase, delayed cell cycle, and decreased cell growth. Gene expression of IL-2 and IL-2 receptors (both alpha and beta) and binding of NF-kappaB to DNA were decreased by zinc deficiency in HuT-78. Decreased production of IL-2 in zinc deficiency may be due to decreased activation of NF-kappaB and subsequent decreased gene expression of IL-2 and IL-2 receptors.

Zinc-regulated genes in Saccharomyces cerevisiae revealed by transposon tagging

The biochemistry of human nutritional zinc deficiency remains poorly defined. To characterize in genetic terms how cells respond to zinc deprivation, zinc-regulated genes (ZRG's) were identified in yeast. Gene expression was probed using random lacZ reporter gene fusions, integrated by transposon tagging into a diploid genome as previously described. About half of the genome was examined. Cells exhibiting differences in lacZ expression on low or moderate ( approximately 0. 1 vs. 10 microm) zinc media were isolated and the gene fusions were sequenced. Ribonuclease protection assays demonstrated four- to eightfold increases for the RNAs of the ZAP1, ZRG17 (YNR039c), DPP1, ADH4, MCD4, and YEF3B genes in zinc-deficient cells. All but YEF3B were shown through reporter gene assays to be controlled by a master regulator of zinc homeostasis now known to be encoded by ZAP1. ZAP1 mutants lacked the flocculence and distended vacuoles characteristic of zinc-deficient cells, suggesting that flocculation and vacuolation serve homeostatic functions in zinc-deficient cells. ZRG17 mutants required extra zinc supplementation to repress these phenotypes, suggesting that ZRG17 functions in zinc uptake. These findings illustrate the utility of transposon tagging as an approach for studying regulated gene expression in yeast.

Effect of zinc supplementation on incidence of infections and hospital admissions in sickle cell disease (SCD)

Zinc deficiency is a common nutritional problem in adult sickle-cell disease (SCD) patients. Hyperzincuria and increased requirement of zinc due to continued hemolysis in SCD are probable bases for zinc deficiency in these patients. Zinc deficiency affects adversely T-helper1 (TH1) functions and cell mediated immunity and interleukin (IL)-2 production is decreased in zinc deficient subjects. We hypothesized that zinc supplementation will improve T-helper1 function and decrease incidence of infections in patients with SCD. We tested this hypothesis in 32 SCD subjects who were divided in three groups (Grs A, B, and C). Grs A (n = 11) and B (n = 10) were zinc deficient based on cellular zinc criteria and Gr C (n = 11) were zinc sufficient. Gr A subjects were observed for 1 year (baseline), following which they received zinc acetate (50 to 75 mg of elemental zinc orally daily) for 3 years. Gr B subjects were observed for 1 year (baseline), following which they received placebo for 1 year and then switched to zinc supplementation (50 to 75 mg of elemental zinc orally daily) for 2 years. Gr C subjects did not receive any intervention inasmuch as they were zinc sufficient. Prolonged zinc supplementation resulted in an increase in lymphocyte and granulocyte zinc (P = 0.0001), and an increase in interleukin-2 production (P = 0.0001), decreased incidence of documented bacteriologically positive infections (P = 0.0026), decreased number of hospitalizations and decreased number of vaso-occlusive pain crisis (P = 0.0001). The predominant pathogens isolated were staphylococci and streptococci involving the respiratory tract and aerobic gram-negative bacteria, particularly Escherichia coli, involving the urinary tract. Further confirmation of our observations will require prospective studies of zinc supplementation in a larger number of SCD patients.

Zinc and immunity

Nutritional deficiency of zinc is widespread throughout the developing countries and a conditioned deficiency of zinc is known to occur in many diseased states. Zinc is known to play an important role in the immune system and zinc deficient subjects may experience increased susceptibility to a variety of pathogens. We have studied the effects of a mild deficiency of zinc on T cells in an experimental model of human zinc deficiency. We showed that T cell functions were affected adversely even when the deficiency of zinc was mild in humans. Characteristically during zinc deficiency, the serum thymulin activity (a thymic hormone) was decreased which was restored following zinc supplementation. Our studies also showed that zinc deficiency caused an imbalance between TH1 and TH2 functions. The production of IFN-g, IL-2, TNF-a (products of TH1 cells) were decreased, whereas the production of IL-4, IL-6 and IL-10 (products of TH2) were not affected during zinc deficiency. T cell subpopulation studies revealed that the CD4+ CD45RA+ to CD4+ CD45RO+ ratio was decreased as a result of zinc deficiency, suggesting that zinc may be required for the regeneration of new CD4+ T cells. We further documented that zinc deficiency decreased NK cell lytic activity and caused a decrease in the percentage of CD8+ CD73+ T cells which are known to be predominantly precursors of cytotoxic T cells. In a suitable cell culture model our studies revealed that the gene expression of a DNA synthesizing enzyme TK was affected adversely which resulted in delayed cell cycle and decreased cell growth. The above immunological consequences of zinc deficiency may be responsible for decreased cell mediated immune functions in zinc deficient subjects.

Nutritional and zinc status of head and neck cancer patients: an interpretive review

In this review, we provide evidence based on our studies, for zinc deficiency and cell mediated immune disorders, and the effects of protein and zinc status on clinical morbidities in patients with head and neck cancer. We investigated subjects with newly diagnosed squamous cell carcinoma of the oral cavity, oropharynx, larynx, and hypopharynx. Patients with metastatic disease and with severe co-morbidity were excluded. Nutritional assessment included dietary history, body composition, and prognostic nutritional index (PNI) determination. Zinc status was determined by zinc assay in plasma, lymphocytes, and granulocytes. Pretreatment zinc status and nutritional status were correlated with clinical outcomes in 47 patients. Assessment of immune functions included production of TH1 and TH2 cytokines, T cell subpopulations and cutaneous delayed hypersensitivity reaction to common antigens. At baseline approximately 50% of our subjects were zinc-deficient based on cellular zinc criteria and had decreased production of TH1 cytokines but not TH2 cytokines, decreased NK cell lytic activity and decreased proportion of CD4+ CD45RA+ cells in the peripheral blood. The tumor size and overall stage of the disease correlated with baseline zinc status but not with PNI, alcohol intake, or smoking. Zinc deficiency was associated with increased unplanned hospitalizations. The disease-free interval was highest for the group which had both zinc sufficient and nutrition sufficient status. Zinc deficiency and cell mediated immune dysfunctions were frequently present in patients with head and neck cancer when seen initially. Zinc deficiency resulted in an imbalance of TH1 and TH2 functions. Zinc deficiency was associated with increased tumor size, overall stage of the cancer and increased unplanned hospitalizations. These observations have broad implications in the management of patients with head and neck cancer.