Zinc homeostasis in humans

A new type of Class C β-lactamases defined by PIB-1. A metal-dependent carbapenem-hydrolyzing β-lactamase, from Pseudomonas aeruginosa: Structural and functional analysis

Antibiotic resistance is one of most important health concerns nowadays, and β-lactamases are the most important resistance determinants. These enzymes, based on their structural and functional characteristics, are grouped in four categories (A, B, C and D). We have solved the structure of PIB-1, a Pseudomonas aeruginosa chromosomally-encoded β-lactamase, in its apo form and in complex with meropenem and zinc. These crystal structures show that it belongs to the Class C β-lactamase group, although it shows notable differences, especially in the Ω- and P2-loops, which are important for the enzymatic activity. Functional analysis showed that PIB-1 is able to degrade carbapenems but not cephalosporins, the typical substrate of Class C β-lactamases, and that its catalytic activity increases in the presence of metal ions, especially zinc. They do not bind to the active-site but they induce the formation of trimers that show an increased capacity for the degradation of the antibiotics, suggesting that this oligomer is more active than the other oligomeric species. While PIB-1 is structurally a Class C β-lactamase, the low sequence conservation, substrate profile and its metal-dependence, prompts us to position this enzyme as the founder of a new group inside the Class C β-lactamases. Consequently, its diversity might be wider than expected.

Applying trace element geochemistry of archaeological bone to study the coevolution of environmental change and human health in the Roman Empire

Technological change has affected human health dating back to at least the Neolithic agricultural revolution. Growing evidence indicates widespread environmental pollution began with metallurgical practices and continues today. Environmental exposures to trace elements released from these practices have the potential to alter human body composition, such as bone mineral chemistry, especially for elements that are not homeostatically regulated. These signals can be used for inferences about human health, particularly when metallotoxins are detected in abundance. Therefore, trace element geochemistry of archaeological bone may provide a means to evaluate human health through time. However, diagenetic factors can hinder attempts to extract this information. Thus, we employed advanced analytical and interpretive methods to carefully distinct groups of European burials over about 1000 years to address questions of potentially toxic trace element exposures. Here, to address our hypothesis that Roman urbanization created one of the earliest urban toxic environment caused by multiple exposures, we present a comprehensive suite of bone trace element compositions of femora from burials spanning three distinct archaeological time periods (Bronze Age, Iron Age, and Roman period). All bone specimens were obtained from the anterior-mid shaft of carefully selected femora and processed using the same analytical techniques designed to mitigate soil contamination. Our data indicate that widespread environmental pollution accelerated in Londinium during the Roman Empire period, leading to conditions where population health would be vulnerable to environmental changes. Specifically, bone lead, silver, vanadium, arsenic, and cadmium concentrations were typically elevated and would likely be associated with multiple toxicities. In addition, bone iron levels were extremely high in some Londinium burials. Our interpretation is that the Romans inhabiting Londinium were not just poisoned by lead exposure as several previous studies show but by several metallotoxins.

Dietary zinc supplements: beneficial health effects and application in food, medicine and animals

Zinc, a crucial trace element is vital for the growth and development of humans. It is frequently described as 'the flower of life' and 'the source of intelligence'. Zinc supplements play a pivotal role in addressing zinc deficiency by serving as a vital source of this essential micronutrients, effectively replenishing depleted zinc levels in the body. In this paper, we first described the biological behavior of zinc in the human body and briefly described the physiological phenomena associated with zinc levels. The benefits and drawbacks of various zinc supplement forms are then discussed, with emphasis on the most recent zinc supplement formulations. Finally, the application of zinc supplements in food, medicine, and animal husbandry is further summarized. © 2024 Society of Chemical Industry.

Zinc and Diabetes: A Connection between Micronutrient and Metabolism

Diabetes mellitus is a global health problem and a major contributor to mortality and morbidity. The management of this condition typically involves using oral antidiabetic medication, insulin, and appropriate dietary modifications, with a focus on macronutrient intake. However, several human studies have indicated that a deficiency in micronutrients, such as zinc, can be associated with insulin resistance as well as greater glucose intolerance. Zinc serves as a chemical messenger, acts as a cofactor to increase enzyme activity, and is involved in insulin formation, release, and storage. These diverse functions make zinc an important trace element for the regulation of blood glucose levels. Adequate zinc levels have also been shown to reduce the risk of developing diabetic complications. This review article explains the role of zinc in glucose metabolism and the effects of its inadequacy on the development, progression, and complications of diabetes mellitus. Furthermore, it describes the impact of zinc supplementation on preventing diabetes mellitus. The available information suggests that zinc has beneficial effects on the management of diabetic patients. Although additional large-scale randomized clinical trials are needed to establish zinc's clinical utility further, efforts should be made to increase awareness of its potential benefits on human health and disease.

Blood and Serum Se and Zn Levels and 10-Year Survival of Patients after a Diagnosis of Kidney Cancer

The aim of the project was to evaluate the association between selenium (Se) and zinc (Zn) levels in blood and serum and kidney cancer mortality. In a prospective group of 284 consecutive, unselected patients with kidney cancer, we evaluated their 10-year survival rate in relation to the levels of Se and Zn in their blood and serum. Micronutrient levels were measured using an inductively coupled plasma mass spectrometer. Patients were divided into quartiles based on the distribution of Se and Zn levels arranged in increasing order. The following variables were taken into account in the multivariable models: age at diagnosis, gender, smoking, type of surgery and histopathological examination results. We observed a statistically significant association of all-cause mortality when subgroups with low blood selenium levels were compared to patients with high selenium levels (HR = 7.74; p < 0.001). We found, in addition, that this correlation was much stronger when only men were assessed (HR = 11.6; p < 0.001). We did not find a statistically significant association for zinc alone. When we combined selenium and zinc levels (SeQI-ZnQI vs. SeQIV-ZnQIV), we observed the hazard ratio for kidney cancer death to be 12.4; p = 0.016. For patients in the highest quartile of blood zinc/selenium ratio, compared to those in the lowest, the HR was 2.53; p = 0.008. Our study suggests that selenium levels, combined selenium and zinc levels (SeQI-ZnQI vs. SeQIV-ZnQIV) and zinc-to-selenium ratio (Zn/Se) are attractive targets for clinical trials aimed at improving the survival of kidney cancer patients.

Unraveling metabolic stress response in dairy cows: genetic control of plasma biomarkers throughout lactation and the transition period

Breeding animals able to effectively respond to stress could be a long-term, sustainable, and affordable strategy to improve resilience and welfare in livestock systems. In the present study, the concentrations of 29 plasma biomarkers were used as candidate endophenotypes for metabolic stress response in single-SNP, gene- and haplotype-based GWAS using 739 healthy lactating Italian Holstein cows and 88,271 variants. Significant genetic associations were found in all the 3 GWAS approaches for plasma γ-glutamyl transferase concentration on BTA17, for paraoxonase on BTA4, and for alkaline phosphatase and zinc on BTA2. On these chromosomes, single-SNP and gene-based chromosome-wide association studies were performed, confirming GWAS findings. The signals identified for paraoxonase, γ-glutamyl transferase, and alkaline phosphatase were in proximity of the genes coding for them. The heritability of these 4 biomarkers ranged from moderate to high (from 0.39 to 0.54). Plasma biomarkers are known to undergo large changes in concentration during metabolic stress in the transition period, with an inter-individual variability in the rate of change and recovery time. Genetics may account in part for these differences. To assess this, we studied a subset of 139 periparturient cows homozygous at 3 SNPs known to be respectively associated with concentration of plasma ceruloplasmin, paraoxonase and γ-glutamyl transferase. We compared the immune-metabolic profile measured in plasma at -7, +5 and +30 d relative to calving between groups of opposite homozygotes. A significant effect of the genotype was found on paraoxonase and γ-glutamyl transferase plasma concentration at all the 3 time points. No evidence for genotype effect was detected for ceruloplasmin. Understanding the genetic control underlying metabolic stress response may suggest new approaches to foster resilience in dairy cows.

The Role of Oral Supplementation for the Management of Age-Related Macular Degeneration: A Narrative Review

The majority of neurodegenerative eye disorders occur with aging and significantly impair quality of life. Age-related macular degeneration (AMD) is the third most common cause of visual impairment and blindness worldwide. One of the most important elements in the pathophysiology of neurodegenerative eye disease is certainly oxidative stress, with neuroinflammation and ocular ischemia which may also be significant factors. Antioxidants, either by food or oral supplementation, may be able to mitigate the deleterious effects of reactive oxygen species that build as a result of oxidative stress, ischemia, and inflammation. Over the past few decades, a number of research works examining the potential adjuvant impact of antioxidants in AMD have been published. In fact, there is not only more and more interest in already known molecules but also in new molecules that can help clinicians in the management of this complex multifactorial disease, such as astaxanthin and melatonin. However, while some studies showed encouraging outcomes, others were conflicting. In addition, more and more attention is also being paid to nutrition, considered a pivotal key point, especially to prevent AMD. For this reason, the purpose of this review is to analyze the main antioxidant molecules currently used as oral supplements for AMD treatment, as well as the role of diet and food intake in this ocular disease, to better understand how all these factors can improve the clinical management of AMD patients.

Modulation of Adverse Health Effects of Environmental Cadmium Exposure by Zinc and Its Transporters

Zinc (Zn) is the second most abundant metal in the human body and is essential for the function of 10% of all proteins. As metals cannot be synthesized or degraded, they must be assimilated from the diet by specialized transport proteins, which unfortunately also provide an entry route for the toxic metal pollutant cadmium (Cd). The intestinal absorption of Zn depends on the composition of food that is consumed, firstly the amount of Zn itself and then the quantity of other food constituents such as phytate, protein, and calcium (Ca). In cells, Zn is involved in the regulation of intermediary metabolism, gene expression, cell growth, differentiation, apoptosis, and antioxidant defense mechanisms. The cellular influx, efflux, subcellular compartmentalization, and trafficking of Zn are coordinated by transporter proteins, solute-linked carriers 30A and 39A (SLC30A and SLC39A), known as the ZnT and Zrt/Irt-like protein (ZIP). Because of its chemical similarity with Zn and Ca, Cd disrupts the physiological functions of both. The concurrent induction of a Zn efflux transporter ZnT1 (SLC30A1) and metallothionein by Cd disrupts the homeostasis and reduces the bioavailability of Zn. The present review highlights the increased mortality and the severity of various diseases among Cd-exposed persons and the roles of Zn and other transport proteins in the manifestation of Cd cytotoxicity. Special emphasis is given to Zn intake levels that may lower the risk of vision loss and bone fracture associated with Cd exposure. The difficult challenge of determining a permissible intake level of Cd is discussed in relation to the recommended dietary Zn intake levels.

Modeling Zinc Absorption in the Adult Population of Colombia: Insights for Nutritional Evaluation and Intervention Strategies

Zinc is a vital trace element, yet its deficiency is common in various populations. This study addresses the gap in understanding zinc intake and its relationship with key nutritional parameters in a Colombian population. We analyzed data from 12,987 individuals, focusing on the daily intake of zinc, phytate, protein, and calcium, and used the phytate/zinc molar ratio as an input parameter in the Miller et al. (2013) model. This model was employed to estimate the total absorbed zinc (TAZ) and the fractional absorption of zinc (FAZ). Our findings highlight a general trend towards insufficient intake compared to the standards of the Institute of Medicine (IOM) and Colombia, with a significant percentage of the population falling below the estimated average requirement (EAR) and recommended daily allowance (RDA) for zinc, underscoring the need for targeted nutritional strategies. Our study contributes to a broader understanding of zinc nutrition and public health implications in Colombia, providing a basis for future dietary guidelines and health interventions.

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Impact of Early Arsenic Exposure on the Mineral Content and Oxidative Status of the Liver and Kidney of Pubescent and Adult Rats

This study evaluated the effect of prepubertal arsenic exposure in the liver and kidney of pubescent rats and their reversibility 30 days after arsenic withdrawal. Male pups of Wistar rats (21 days old) were divided into two groups (n = 20/group): control animals received filtered water, and exposed rats received 10 mg L-1 arsenic from postnatal day (PND) 21 to PND 51. The liver and kidney of 52 days old rats (n = 10/group) were examined to investigate the effects of arsenic on micromineral content, antioxidant enzyme activity, histology, and biochemistry parameters. The other animals were kept alive under free arsenic conditions until 82 days old and further analyzed by the same parameters. Our results revealed that 52-day-old rats increased arsenic content in their liver and arsenic and manganese in their kidney. In those animals, glycogen and zinc content and catalase activity were reduced in the liver, and the selenium content decreased in the kidney. Thirty days later, arsenic reduced the manganese and iron content and SOD and CAT activity in the liver of 82-day-old rats previously exposed to arsenic, while glycogen and selenium content decreased in their kidney. In contrast, PND 82 rats exhibited higher retention of copper in the liver, an increase in iron and copper content, and CAT and GST activity in the kidney. Significant histological alterations of liver and kidney tissues were not observed in rats of both ages. We conclude that arsenic-induced toxicity could alter differently the oxidative status and balance of trace elements in pubertal and adult rats, demonstrating that the metalloid can cause effects in adulthood.

Zinc Supplementation Reduces Testicular Cell Apoptosis in Mice and Improves Spermatogenic Dysfunction Caused by Marginal Zinc Deficiency

Zinc (Zn) is an important trace element in the human body and plays an important role in growth, development, and male reproductive functions. Marginal zinc deficiency (MZD) is common in the human population and can cause spermatogenic dysfunction in males. Therefore, the aim of this study was to investigate methods to improve spermatogenic dysfunction caused by MZD and to further explore its mechanism of action. A total of 75 4-week-old male SPF ICR mice were randomly divided into five groups (control, MZD, MZD + ZnY2, MZD + ZnY4, and MZD + ZnY8, 15 mice per group). The dietary Zn content was 30 mg/kg in the control group and 10 mg/kg in the other groups. From low to high, the Zn supplementation doses administered to the three groups were 2, 4, and 8 mg/kg·bw. After 35 days, the zinc content, sperm quality, activity of spermatogenic enzymes, oxidative stress level, and apoptosis level of the testes in mice were determined. The results showed that MZD decreased the level of Zn in the serum, sperm quality, and activity of spermatogenic enzymes in mice. After Zn supplementation, the Zn level in the serum increased, sperm quality was significantly improved, and spermatogenic enzyme activity was restored. In addition, MZD reduced the content of antioxidants (copper-zinc superoxide dismutase (Cu-Zn SOD), metallothionein (MT), and glutathione (GSH) and promoted malondialdehyde (MDA) production. The apoptosis index of the testis also increased significantly in the MZD group. After Zn supplementation, the level of oxidative stress decreased, and the apoptosis index in the testis was reduced. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) showed that the expression of B-cell lymphoma-2 (Bcl-2) mRNA and Bcl-2/BCL2-associated X (Bax) in the control group decreased in testicular cells, and their expression was restored after Zn supplementation. The results of this study indicated that Zn supplementation can reduce the level of oxidative stress and increase the ability of testicular cells to resist apoptosis, thereby improving spermatogenic dysfunction caused by MZD in mice.

The Role of Zinc on Liver Fibrosis by Modulating ZIP14 Expression Throughout Epigenetic Regulatory Mechanisms

Zinc plays a pivotal role in tissue regeneration and maintenance being as a central cofactor in a plethora of enzymatic activities. Hypozincemia is commonly seen with chronic liver disease and is associated with an increased risk of liver fibrosis development and hepatocellular carcinoma. Previously favorable effects of zinc supplementation on liver fibrosis have been shown. However, the underlying mechanism of this effect is not elucidated. Liver fibrosis was induced in mice by using CCl4 injection, followed by treatment with zinc chloride (ZnCl2) both at fibrotic and sham groups, and their hepatocytes were isolated. Our results showed that the administration of ZnCl2 restored the depleted cytosolic zinc levels in the hepatocytes isolated from the fibrotic group. Also, alpha-smooth muscle actin (αSMA) expression in hepatocytes was decreased, indicating a reversal of the fibrotic process. Notably, ZIP14 expression significantly increased in the fibrotic group following ZnCl2 treatment, whereas in the sham group ZIP14 expression decreased. Chromatin immunoprecipitation (ChIP) experiments revealed an increased binding percentage of Metal-regulatory transcription factor 1 (MTF1) on ZIP14 promoter in the hepatocytes isolated from fibrotic mice compared to the sham group after ZnCl2 administration. In the same group, the binding percentage of the histone deacetylase HDAC4 on ZIP14 promoter decreased. Our results suggest that the ZnCl2 treatment ameliorates liver fibrosis by elevating intracellular zinc levels through MTF1-mediated regulation of ZIP14 expression and the reduction of ZIP14 deacetylation via HDAC4. The restoration of intracellular zinc concentrations and the modulation of ZIP14 expression by zinc orchestrated through MTF1 and HDAC4, appear to be essential determinants of the therapeutic response in hepatic fibrosis. These findings pave the way for potential novel interventions targeting zinc-related pathways for the treatment of liver fibrosis and associated conditions.

Associations of Whole Blood Zinc Levels with Coronary Artery Calcification and Future Cardiovascular Events in CKD Patients

This study was conducted to compare the differences of the whole blood zinc concentration in patients with chronic kidney disease (CKD) as compared to healthy controls, and to explore the correlations of the whole blood zinc level with coronary artery calcification (CAC) and cardiovascular event (CVE) in CKD patients. A total of 170 CKD patients and 62 healthy controls were recruited. The whole blood zinc concentration was determined in using atomic absorption spectroscopy (AAS) method. The degrees of CAC were evaluated by Agatston score based on computed tomography (CT). Regular follow-up visits were performed to record the incidence of CVE, and risk factors were analyzed by COX proportional hazard model and Kaplan-Meier survival curve. There were statistically significant lower zinc levels in CKD patients than in healthy population. The prevalence of CAC was 58.82% in CKD patients. Correlation analysis showed that dialysis duration, intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), 25-hydroxyvitamin D3 (25(OH)D3), neutrophil-lymphocyte ratio (NLR), total cholesterol (TC), and high-sensitive C-reactive protein (Hs-CRP) were positively correlated with CAC, while albumin (ALB), hemoglobin (Hb), and zinc levels were negatively associated with CAC. Further COX proportional hazard model demonstrated that moderate to severe CAC, NLR, phosphate, 25(OH)D3, iPTH, and high-density lipoprotein (HDL) were associated with an increased risk for CVE, while zinc levels, Hb, and ALB were inversely associated with a reduced risk for CVE. Kaplan-Meier curve showed that low zinc (zinc < 86.62 μmol/L) patients and moderate to severe CAC patients had lower survival respectively. Our study found the lower levels of zinc and higher prevalence of CAC in CKD patients; the low zinc is involved in the high incidence rate of moderate to severe CAC and CVE in CKD patients.

Roles of zinc in cancers: From altered metabolism to therapeutic applications

Zinc (Zn) is a crucial trace element involved in various cellular processes, including oxidative stress, apoptosis and immune response, contributing to cellular homeostasis. Dysregulation of Zn homeostasis occurs in certain cancers. This review discusses the role of Zn in cancer and its associated components, such as Zn-related proteins, their potential as biomarkers and the use of Zn-based strategies for tumor treatment. ZIP and ZnT proteins regulate Zn metabolism under normal conditions, but their expression is aberrant in cancer. These Zn proteins can serve as prognostic or diagnostic biomarkers, aiding in early cancer detection and disease monitoring. Moreover, targeting Zn and its pathways offers potential therapeutic approaches for cancer treatment. Modulating Zn biodistribution within cells using metal-binding agents allows for the control of downstream signaling pathways. Direct utilization of zinc as a therapeutic agent, including Zn supplementation or Zn oxide nanoparticle administration, holds promise for improving the prognosis of cancer patients.

Recent progress in the role of endogenous metal ions in doxorubicin-induced cardiotoxicity

Doxorubicin is a widely used anticancer drug in clinical practice for the treatment of various human tumors. However, its administration is associated with cardiotoxicity. Administration of doxorubicin with low side effects for cancer treatment and prevention are, accordingly, urgently required. The human body harbors various endogenous metal ions that exert substantial influences. Consequently, extensive research has been conducted over several decades to investigate the potential of targeting endogenous metal ions to mitigate doxorubicin's side effects and impede tumor progression. In recent years, there has been a growing body of research indicating the potential efficacy of metal ion-associated therapeutic strategies in inhibiting doxorubicin-induced cardiotoxicity (DIC). These strategies offer a combination of favorable safety profiles and potential clinical utility. Alterations in intracellular levels of metal ions have been found to either facilitate or mitigate the development of DIC. For instance, ferroptosis, a cellular death mechanism, and metal ions such as copper, zinc, and calcium have been identified as significant contributors to DIC. This understanding can contribute to advancements in cancer treatment and provide valuable insights for mitigating the cardiotoxic effects of other therapeutic drugs. Furthermore, potential therapeutic strategies have been investigated to alleviate DIC in clinical settings. The ultimate goal is to improve the efficacy and safety of Dox and offer valuable insights for future research in this field.

Potentially toxic elements in different tissues of great cormorant (Phalacrocorax carbo) at a wetland area

Concentrations of 4 potentially toxic elements (As, Cd, Hg, Pb) were investigated in the feather, liver, kidney, and bone of great cormorants (Phalacrocorax carbo). The tissue samples were taken at the Central Tisza - Jászság Nature Conservation Area in Hungary. They were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The goal of the investigation was to analyse the metal burden of the above-mentioned elements in the various tissues of these wild birds and to provide important information for monitoring the environmental pollution.Amongst the examined potentially toxic elements no statistical gender difference was observed, so the data were not separated based on them during the statistical analysis. The concentration of mercury was the highest in the feather, followed by the liver, kidney, and bone. The lead was detected in the feather with the highest level followed by the kidney, liver, and bone. The cadmium was determined in all investigated tissues with the next descending order: kidney > bone > liver > feather. Highest arsenic concentration was measured in the feather, followed by liver, kidney, and bone with the same concentration.The detected concentrations of the investigated potentially toxic elements in different tissues of great cormorants (feathers, liver, kidney, bone) means that the living area of this birds is not highly contaminated to induce health problems or toxic signs, or even other undesirable effect in the animals.

Zinc Overload Induces Damage to H9c2 Cardiomyocyte Through Mitochondrial Dysfunction and ROS-Mediated Mitophagy

Zinc homeostasis is essential for maintaining redox balance, cell proliferation, and apoptosis. However, excessive zinc exposure is toxic and leads to mitochondrial dysfunction. In this study, we established a zinc overload model by treating rat cardiomyocyte H9c2 cells with Zn2+ at different concentrations. Our results showed that zinc overload increased LDH and reactive oxygen species (ROS) levels, leading to cell death, mitochondrial membrane potential decrease and impaired mitochondrial function and dynamics. Furthermore, zinc overload activated the PINK1/Parkin signaling pathway and induced mitochondrial autophagy via ROS, while NAC inhibited mitophagy and weakened the activation of PINK1/Parkin pathway, thereby preserving mitochondrial biogenesis. In addition, our data also showed that Mfn2 deletion increased ROS production and exacerbated cytotoxicity induced by zinc overload. Our results therefore suggest that Zn2+-induced ROS generation causes mitochondrial autophagy and mitochondrial dysfunction, damaging H9c2 cardiomyocytes. Additionally, Mfn2 may play a key role in zinc ion-mediated endoplasmic reticulum and mitochondrial interactions. Our results provide a new perspective on zinc-induced toxicology.

Metal transporter SLC39A14/ZIP14 modulates regulation between the gut microbiome and host metabolism

Metal transporter SLC39A14/ZIP14 is localized on the basolateral side of the intestine, functioning to transport metals from blood to intestine epithelial cells. Deletion of Slc39a14/Zip14 causes spontaneous intestinal permeability with low-grade chronic inflammation, mild hyperinsulinemia, and greater body fat with insulin resistance in adipose. Importantly, antibiotic treatment reverses the adipocyte phenotype of Slc39a14/Zip14 knockout (KO), suggesting a potential gut microbial role in the metabolic alterations in the Slc39a14/Zip14 KO mice. Here, we investigated the hypothesis that increased intestinal permeability and subsequent metabolic alterations in the absence of Zip14 could be in part due to alterations in gut microbial composition. Dietary metals have been shown to be involved in the regulation of gut microbial diversity and composition. However, studies linking the action of intestinal metal transporters to gut microbial regulation are lacking. We showed the influence of deletion of metal transporter Slc39a14/Zip14 on gut microbiome composition and how ZIP14-linked changes to gut microbiome community composition are correlated with changes in host metabolism. Deletion of Slc39a14/Zip14 generated Zn-deficient epithelial cells and luminal content in the entire intestinal tract, a shift in gut microbial composition that partially overlapped with changes previously associated with obesity and inflammatory bowel disease (IBD), increased the fungi/bacteria ratio in the gut microbiome, altered the host metabolome, and shifted host energy metabolism toward glucose utilization. Collectively, our data suggest a potential predisease microbial susceptibility state dependent on host gene Slc39a14/Zip14 that contributes to intestinal permeability, a common trait of IBD, and metabolic disorders such as obesity and type 2 diabetes.NEW & NOTEWORTHY Metal dyshomeostasis, intestinal permeability, and gut dysbiosis are emerging signatures of chronic disorders, including inflammatory bowel diseases, type-2 diabetes, and obesity. Studies in reciprocal regulations between host intestinal metal transporters genes and gut microbiome are scarce. Our research revealed a potential predisease microbial susceptibility state dependent on the host metal transporter gene, Slc39a14/Zip14, that contributes to intestinal permeability providing new insight into understanding host metal transporter gene-microbiome interactions in developing chronic disease.

Associations between blood essential metal mixture and serum uric acid: a cross-sectional study

Introduction

Although several studies have explored the associations between single essential metals and serum uric acid (SUA), the study about the essential metal mixture and the interactions of metals for hyperuricemia remains unclear.

Methods

We performed a cross-sectional study to explore the association of the SUA levels with the blood essential metal mixture, including magnesium (Mg), calcium (Ca), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn) in Chinese community-dwelling adults (n=1039). The multivariable linear regression, the weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were conducted to estimate the associations of blood essential metals with SUA levels and the BKMR model was also conducted to estimate the interactions of the essential metals on SUA.

Results

In the multivariable linear regression, the association of blood Mg, Mn, and Cu with SUA was statistically significant, both in considering multiple metals and a single metal. In WQS regression [β=13.59 (95%CI: 5.57, 21.60)] and BKMR models, a positive association was found between the mixture of essential metals in blood and SUA. Specifically, blood Mg and Cu showed a positive association with SUA, while blood Mn showed a negative association. Additionally, no interactions between individual metals on SUA were observed.

Discussion

In conclusion, further attention should be paid to the relationship between the mixture of essential metals in blood and SUA. However, more studies are needed to confirm these findings.

Bacteria from the gut influence the host micronutrient status

Micronutrient deficiencies or "hidden hunger" remains a serious public health problem in most low- and middle-income countries, with severe consequences for child development. Traditional methods of treatment and prevention, such as supplementation and fortification, have not always proven to be effective and may have undesirable side-effects (i.e., digestive troubles with iron supplementation). Commensal bacteria in the gut may increase bioavailability of specific micronutrients (i.e., minerals), notably by removing anti-nutritional compounds, such as phytates and polyphenols, or by the synthesis of vitamins. Together with the gastrointestinal mucosa, gut microbiota is also the first line of protection against pathogens. It contributes to the reinforcement of the integrity of the intestinal epithelium and to a better absorption of micronutrients. However, its role in micronutrient malnutrition is still poorly understood. Moreover, the bacterial metabolism is also dependent of micronutrients acquired from the gut environment and resident bacteria may compete or collaborate to maintain micronutrient homeostasis. Gut microbiota composition can therefore be modulated by micronutrient availability. This review brings together current knowledge on this two-way relationship between micronutrients and gut microbiota bacteria, with a focus on iron, zinc, vitamin A and folate (vitamin B9), as these deficiencies are public health concerns in a global context.

Botulinum Toxins and Zinc: From Theory to Practice-A Systematic Review

OBJECTIVE

The aims of this study were to determine whether zinc supplementation affects botulinum toxin's effect and longevity and to establish a transition from the molecular to the clinical aspect.

METHODS

We conducted a systematic review in which we included all published studies on PubMed and Embase using the combination of the following terms: "zinc" AND (botox OR botulinum OR onabotulinumtoxinA OR abobotulinumtoxinA OR incobotulinumtoxinA).

RESULTS

From the 260 yielded articles, 3 randomized control trials and 1 case report were retained. Three of them found a significant improvement with zinc supplementation in the toxin's effect and longevity. This was observed in neurological conditions and cosmetic uses.

CONCLUSIONS

Zinc supplementation could be an interesting asset in the potentialization of botulinum neurotoxin effect and longevity. Larger clinical trials and objective measurement tools should be used to further defining the role of zinc in maximizing botulinum neurotoxin effect.

Loss of zinc transporters ZIP1 and ZIP3 augments platelet reactivity in response to thrombin and accelerates thrombus formation in vivo

Zinc (Zn2+) is considered as important mediator of immune cell function, thrombosis and haemostasis. However, our understanding of the transport mechanisms that regulate Zn2+ homeostasis in platelets is limited. Zn2+ transporters, ZIPs and ZnTs, are widely expressed in eukaryotic cells. Using mice globally lacking ZIP1 and ZIP3 (ZIP1/3 DKO), our aim was to explore the potential role of these Zn2+ transporters in maintaining platelet Zn2+ homeostasis and in the regulation of platelet function. While ICP-MS measurements indicated unaltered overall Zn2+ concentrations in platelets of ZIP1/3 DKO mice, we observed a significantly increased content of FluoZin3-stainable free Zn2+, which, however, appears to be released less efficiently upon thrombin-stimulated platelet activation. On the functional level, ZIP1/3 DKO platelets exhibited a hyperactive response towards threshold concentrations of G protein-coupled receptor (GPCR) agonists, while immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptor agonist signalling was unaffected. This resulted in enhanced platelet aggregation towards thrombin, bigger thrombus volume under flow ex vivo and faster in vivo thrombus formation in ZIP1/3 DKO mice. Molecularly, augmented GPCR responses were accompanied by enhanced Ca2+ and PKC, CamKII and ERK1/2 signalling. The current study thereby identifies ZIP1 and ZIP3 as important regulators for the maintenance of platelet Zn2+ homeostasis and function.

In vivo biocompatibility of ZIF-8 for slow release via intranasal administration

Zeolitic imidazolate framework-8 (ZIF-8) is becoming popular in research for its potential in antigen protection and for providing a thermally stable, slow-release platform. While papers applying this material for immunological applications are aplenty in the literature, studies that explore the biosafety of ZIF-8 in mammals-especially when administered intranasally-are not well represented. We checked the body clearance of uncoated and ZIF-8-coated liposomes and observed that the release slowed as ZIF-8 is easily degraded by mucosal fluid in the nasal cavity. We delivered varying doses of ZIF-8, checked its short- and long-term effects on diagnostic proteins found in blood serum, and found no noticeable differences from the saline control group. We also studied their lung diffusing capacity and tissue morphology; neither showed significant changes in morphology or function.

Clinical and biochemical understanding of Zinc interaction during liver diseases: A paradigm shift

Zinc (Zn) is an essential and the second most abundant trace element after Iron. It can apply antioxidant, anti-inflammatory, and anti-apoptotic activity. It is assumed to be indispensable for cell division, cellular differentiation and cell signalling. Zinc is essential for proper liver function which is also the site of its metabolism. Depleted Zn concentrations have been observed in both acute and chronic hepatic diseases. It is reported that Zn deficiency or abnormal Zn metabolism during majority of liver diseases is attributed to deficient dietary intake of Zn, augmented disposal of Zn in the urine, activation of certain Zn transporters, and expression of hepatic metallothionein. Undoubtedly, Zn is involved in generating many diseases but how and whether it plays role from acute to fulminant stage of all chronic liver diseases remains to be cleared. Here, we will discuss the role of Zn in development of different diseases specifically the involvement of Zn to understand the aetiology and intricate mechanism of dynamic liver diseases.

Improving Dietary Zinc Bioavailability Using New Food Fortification Approaches: A Promising Tool to Boost Immunity in the Light of COVID-19

Zinc is a powerful immunomodulatory trace element, and its deficiency in the body is closely associated with changes in immune functions and viral infections, including SARS-CoV-2, the virus responsible for COVID-19. The creation of new forms of zinc delivery to target cells can make it possible to obtain smart chains of food ingredients. Recent evidence supports the idea that the optimal intake of zinc or bioactive compounds in appropriate supplements should be considered as part of a strategy to generate an immune response in the human body. Therefore, controlling the amount of this element in the diet is especially important for populations at risk of zinc deficiency, who are more susceptible to the severe progression of viral infection and disease, such as COVID-19. Convergent approaches such as micro- and nano-encapsulation develop new ways to treat zinc deficiency and make zinc more bioavailable.

Dexamethasone leads to Zn2+ accumulation and increased unbound Zn2+ in C2C12 muscle and 3T3-L1 adipose cells

Skeletal muscle atrophy is associated with increases in circulating glucocorticoid levels and insulin resistance. Zinc accumulates in atrophic muscle, but the relationship between atrophy, insulin resistance, and Zn²⁺ homeostasis remains unclear. In this study, the effect of the glucocorticoid dexamethasone (DEX) on insulin and Zn²⁺ homeostasis was explored. Treatment of differentiated C2C12 skeletal myotubes and 3T3-L1 adipocytes with DEX significantly increased mRNA expression of the metal-binding proteins Mt1 and 2 and altered energy storage as shown by the increased size of lipid droplets in 3T3-L1 cells. In C2C12 cells the total cellular Zn²⁺ was higher after DEX treatment, and in both C2C12 and 3T3-L1 adipocytes, free unbound Zn²⁺ was increased. Insulin treatment led to a gradual increase in free Zn²⁺ in C2C12 cells, and no significant change in DEX-treated cells such that concentrations were similar 10 min after insulin treatment. These data demonstrate that DEX disturbs Zn²⁺ homeostasis in muscle and fat cells. Further study of the molecular pathways involved to identify novel therapeutic targets for treatment of skeletal muscle atrophy is warranted.

Zinc Supplementation Induced Transcriptional Changes in Primary Human Retinal Pigment Epithelium: A Single-Cell RNA Sequencing Study to Understand Age-Related Macular Degeneration

Zinc supplementation has been shown to be beneficial to slow the progression of age-related macular degeneration (AMD). However, the molecular mechanism underpinning this benefit is not well understood. This study used single-cell RNA sequencing to identify transcriptomic changes induced by zinc supplementation. Human primary retinal pigment epithelial (RPE) cells could mature for up to 19 weeks. After 1 or 18 weeks in culture, we supplemented the culture medium with 125 µM added zinc for one week. RPE cells developed high transepithelial electrical resistance, extensive, but variable pigmentation, and deposited sub-RPE material similar to the hallmark lesions of AMD. Unsupervised cluster analysis of the combined transcriptome of the cells isolated after 2, 9, and 19 weeks in culture showed considerable heterogeneity. Clustering based on 234 pre-selected RPE-specific genes divided the cells into two distinct clusters, we defined as more and less differentiated cells. The proportion of more differentiated cells increased with time in culture, but appreciable numbers of cells remained less differentiated even at 19 weeks. Pseudotemporal ordering identified 537 genes that could be implicated in the dynamics of RPE cell differentiation (FDR < 0.05). Zinc treatment resulted in the differential expression of 281 of these genes (FDR < 0.05). These genes were associated with several biological pathways with modulation of ID1/ID3 transcriptional regulation. Overall, zinc had a multitude of effects on the RPE transcriptome, including several genes involved in pigmentation, complement regulation, mineralization, and cholesterol metabolism processes associated with AMD.

Increased Intracellular Free Zinc Has Pleiotropic Effects on Doxorubicin-Induced Cytotoxicity in hiPCS-CMs Cells

(1) the mechanisms and outcomes of doxorubicin (DOX)-dependent toxicity upon changed intracellular zinc (Zn) concentrations in the cardiomyocytes obtained from human-induced pluripotent stem cells (hiPCS-CMs) were investigated; (2) cells exposed to the DOX were pretreated or cotreated with zinc pyrythione (ZnPyr) and various cellular endpoints and mechanisms were analyzed via cytometric methods; (3) both DOX concentrations (0.3 and 1 µM) induced a concentration-dependent loss of viability, an activation of autophagy, cell death, and the appearance of senescence. These phenotypes were preceded by an oxidative burst, DNA damage, and a loss of mitochondrial and lysosomal integrity. Furthermore, in DOX-treated cells, proinflammatory and stress kinase signaling (in particular, JNK and ERK) were upregulated upon the loss of free intracellular Zn pools. Increased free Zn concentrations proved to have both inhibitory and stimulatory effects on the investigated DOX-related molecular mechanisms, as well as on signaling pathways on the resulting cell fates; and (4) free intracellular Zn pools, their status, and their elevation might have, in a specific context, a pleiotropic impact upon DOX-dependent cardiotoxicity.

Small-molecule fluorogenic probes for mitochondrial nanoscale imaging

Mitochondria are inextricably linked to the development of diseases and cell metabolism disorders. Super-resolution imaging (SRI) is crucial in enhancing our understanding of mitochondrial ultrafine structures and functions. In addition to high-precision instruments, super-resolution microscopy relies heavily on fluorescent materials with unique photophysical properties. Small-molecule fluorogenic probes (SMFPs) have excellent properties that make them ideal for mitochondrial SRI. This paper summarizes recent advances in the field of SMFPs, with a focus on the chemical and spectroscopic properties required for mitochondrial SRI. Finally, we discuss future challenges in this field, including the design principles of SMFPs and nanoscopic techniques.

Zinc deficiency associated with cutaneous toxicities induced by epidermal growth factor receptor tyrosine kinase inhibitor therapy in patients with lung adenocarcinoma

PURPOSE

Cutaneous toxicities are common adverse effects following epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy. Zinc deficiency causes diverse diseases, including skin toxicities. Therefore, this study aimed to investigate the role of zinc deficiency in patients with EGFR-TKI-induced skin toxicities.

EXPERIMENTAL DESIGN

This retrospective study enrolled 269 patients with diverse skin disorders who visited our hospital between January 2016 and December 2017. The skin toxicity severities and plasma zinc levels of 101 EGFR-TKI-treated cancer patients were analysed and compared with those of 43 non-EGFR-TKI-treated cancer patients and 125 patients without cancer but presenting cutaneous manifestations. Additionally, the role of zinc in erlotinib-induced skin eruptions was established in a 14-day-murine model. Clinical features were further evaluated following systemic zinc supplementation in EGFR-TKI-treated cancer patients.

RESULTS

EGFR-TKI-treated patients demonstrated severe cutaneous manifestations and a significant decrease in plasma zinc levels than those of the control groups. The serum zinc level and Common Terminology Criteria for Adverse Events (CTCAE) 5.0 grading of EGFR-TKI-induced skin toxicities showed a significant negative correlation (r = -0.29; p < 0.0001). Moreover, erlotinib treatment decreased the plasma zinc levels and induced periorificial dermatitis in rats confirming zinc deficiency following EGFR-TKI treatment. Zinc supplementation to the EGFR-TKI-treated cancer patients showed a significant decrease in the CTCEA grading (p < 0.0005 for mucositis and p < 0.0.0001 for all other cases) after 8 weeks.

CONCLUSIONS

Skin impairment following EGFR-TKI therapy could be ameliorated through zinc supplementation. Thus, zinc supplementation should be considered for cancer patients undergoing EGFR-TKI therapy.

Assessment of intracellular zinc levels in infants with food protein-induced allergic proctocolitis

BACKGROUND

Food protein-induced allergic proctocolitis (FPIAP) is characterized by bloody stools in well-appearing infants. Zinc is a micronutrient that plays a crucial role in immune modulation and is essential for cellular function during immune response. Although there are studies on the assessment of intracellular zinc levels in allergic diseases, no data is available on erythrocyte zinc levels of patients with FPIAP.

OBJECTIVE

This study aimed to assess the erythrocyte zinc levels of children with allergic proctocolitis and compare zinc levels with clinical and demographic characteristics.

METHODS

This was a case-control study that prospectively compared 50 patients with FPIAP and 50 healthy children without malnutrition. The erythrocyte zinc levels of children were determined using atomic absorption spectrophotometry.

RESULTS

Fifty patients with FPIAP, including 28 (51%) girls, with median age of 7.1 ± 2.9 (3-14) months and 50 healthy children, including 26 (53.1%) girls, with median age of 7.7 ± 2.8 (3-13) months were included in the study. Seventy percent (n = 35) of the patients with FPIAP started to have symptoms while they were exclusively breastfeeding. Offending allergen foods were cow's milk (78%), egg (40%), sesame (10%), hazelnut (8%), almond (6%), beef (6%), and peanuts (6%, n = 3). Intracellular (erythrocyte) zinc levels in patients with FPIAP were lower than in the healthy control group (495.5 ± 134 µg/dL, 567.3 ± 154.4 µg/dL, respectively, P = 0.01). Patients with FPIAP aged younger than 6 months had lower intracellular zinc levels compared with those aged above 6 months (457 ± 137 µg/dL; 548 ± 112 µg/dL, respectively, P = 0.01). There was no relationship between zinc levels and time of symptom onset, presence of concomitant disease, being allergic to multiple foods, and family history of atopy (P > 0.05).

CONCLUSIONS

FPIAP is a food allergy with limited information on its pathogenesis. Considering the beneficial effects on gastrointestinal system epithelia, zinc may be involved in the pathogenesis of FPIAP. Future comprehensive prospective research on this subject is of importance.

The Important Role of Zinc in Neurological Diseases

Zinc is one of the most abundant metal ions in the central nervous system (CNS), where it plays a crucial role in both physiological and pathological brain functions. Zinc promotes antioxidant effects, neurogenesis, and immune system responses. From neonatal brain development to the preservation and control of adult brain function, zinc is a vital homeostatic component of the CNS. Molecularly, zinc regulates gene expression with transcription factors and activates dozens of enzymes involved in neuronal metabolism. During development and in adulthood, zinc acts as a regulator of synaptic activity and neuronal plasticity at the cellular level. There are several neurological diseases that may be affected by changes in zinc status, and these include stroke, neurodegenerative diseases, traumatic brain injuries, and depression. Accordingly, zinc deficiency may result in declines in cognition and learning and an increase in oxidative stress, while zinc accumulation may lead to neurotoxicity and neuronal cell death. In this review, we explore the mechanisms of brain zinc balance, the role of zinc in neurological diseases, and strategies affecting zinc for the prevention and treatment of these diseases.

Adverse Effects of Excessive Zinc Intake in Infants and Children Aged 0-3 Years: A Systematic Review and Meta-Analysis

Zinc supplementation reduces morbidity, but evidence suggests that excessive intakes can have negative health consequences. Current guidelines of upper limits (ULs) of zinc intake for young children are extrapolated from adult data. This systematic review (PROSPERO; registration no. CRD42020215187) aimed to determine the levels of zinc intake at which adverse effects are observed in young children. Studies reporting potential adverse effects of zinc intake in children aged 0-3 y were identified (from inception to August 2020) in MEDLINE, Embase, and the Cochrane Library, with no limits on study design. Adverse clinical and physical effects of zinc intake were synthesized narratively, and meta-analyses of biochemical outcomes were conducted. Random effects models were used to generate forest plots to examine the evidence by age category, dose, dose duration, chemical formula of zinc, and zinc compared with placebo. The Joanna Briggs Institute Critical Appraisal Checklist, Cochrane Risk of Bias 2, and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guideline were employed to assess risk of bias and to appraise the certainty of evidence. Fifty-eight studies assessed possible adverse effects of zinc doses ranging from 3 to 70 mg/d. Data from 39 studies contributed to meta-analyses. Zinc supplementation had an adverse effect on serum ferritin, plasma/serum copper concentration, serum transferrin receptor, hemoglobin, hematocrit, and the odds of anemia in ≥1 of the subgroups investigated. Lactulose:mannitol ratio was improved with zinc supplementation, and no significant effect was observed on C-reactive protein, erythrocyte superoxide dismutase, zinc protoporphyrin, blood cholesterol, and iron deficiency anemia. The certainty of the evidence, as assessed using GRADE, was very low to moderate. Although possible adverse effects of zinc supplementation were observed in some subgroups, it is unclear whether these findings are clinically important. The synthesized data can be used to undertake a dose-response analysis to update current guidelines of ULs of zinc intake for young children.

Association between Serum Zinc and Toll-like-Receptor- Related Innate Immunity and Infectious Diseases in Well-Nourished Children with a Low Prevalence of Zinc Deficiency: A Prospective Cohort Study

Existing reports focus on zinc-associated immunity and infection in malnourished children; however, whether zinc also plays an important role in the immune homeostasis of the non-zinc-deficient population remained unknown. This study aimed to investigate the association between zinc status and toll-like receptor (TLR)-related innate immunity and infectious outcome in well-nourished children. A total of 961 blood samples were collected from 1 through 5 years of age. Serum zinc was analyzed, and mononuclear cells isolated to assess TNF-α, IL-6, and IL-10 production by ELISA after stimulation with TLR ligands. Childhood infections were analyzed as binary outcomes with logistic regression. The prevalence of zinc deficiency was 1.4-9.6% throughout the first 5 years. There was significant association between zinc and TLR-stimulated cytokine responses. Higher serum zinc was associated with decreased risk of ever having pneumonia (aOR: 0.94; 95% CI: 0.90, 0.99) at 3 years, and enterocolitis (aOR: 0.96; 95% CI: 0.93, 0.99) at 5 years. Serum zinc was lower in children who have had pneumonia before 3 years of age (72.6 ± 9 vs. 81.9 ± 13 μg/dL), and enterocolitis before 5 years (89.3 ± 12 vs. 95.5 ± 13 μg/dL). We emphasize the importance of maintaining optimal serum zinc in the young population.

Local zinc treatment enhances fracture callus properties in diabetic rats

The effects of locally applied zinc chloride (ZnCl₂ ) on early and late-stage parameters of fracture healing were evaluated in a diabetic rat model. Type 1 Diabetes has been shown to negatively impact mechanical parameters of bone as well as biologic markers associated with bone healing. Zinc treatments have been shown to reverse those outcomes in tests of nondiabetic and diabetic animals. This study is the first to assess the efficacy of a noncarrier mediated ZnCl₂ on bony healing in diabetic animals. This is a promising basic science approach which may lead to benefits for diabetic patients in the future. Treatment and healing were assessed through quantification of callus zinc, radiographic scoring, microcomputed tomography (µCT), histomorphometry, and mechanical testing. Local ZnCl₂ treatment increased callus zinc levels at 1 and 3 days after fracture (p ≤ 0.025). Femur fractures treated with ZnCl₂ showed increased mechanical properties after 4 and 6 weeks of healing. Histomorphometry of the ZnCl₂ -treated fractures found increased callus cartilage area at Day 7 (p = 0.033) and increased callus bone area at Day 10 (p = 0.038). In contrast, callus cartilage area was decreased (p < 0.01) after 14 days in the ZnCl₂ -treated rats. µCT analysis showed increased bone volume in the fracture callus of ZnCl₂ -treated rats at 6 weeks (p = 0.0012) with an associated increase in the proportion of µCT voxel axial projections (Z-rays) spanning the fracture site. The results suggest that local ZnCl₂ administration improves callus chondrogenesis leading to greater callus bone formation and improved fracture healing in diabetic rats.

Zinc in Prostate Health and Disease: A Mini Review

Introduction-With the high global prevalence of prostate cancer and associated mortalities, it is important to enhance current clinical practices for better prostate cancer outcomes. The current review is towards understanding the value of Zn towards this mission. Method-General information on Zn in biology and multiple aspects of Zn involvement in prostate health and disease were referred to in PubMed. Results-The most influential feature of Zn towards prostate health is its ability to retain sufficient citrate levels for a healthy prostate. Zn deficiencies were recorded in serum, hair, and prostate tissue of men with prostate cancer compared to non-cancer controls. Zn gut absorption, albumin binding, and storage compete with various factors. There are multiple associations of Zn cellular influx and efflux transporters, Zn finger proteins, matrix metalloproteinases, and Zn signaling with prostate cancer outcomes. Such Zn marker variations associated with prostate cancer recorded from biological matrices may improve algorithms for prostate cancer screening, prognosis, and management when coupled with standard clinical practices. Discussion-The influence of Zn in prostatic health and disease is multidimensional, therefore more personalized Zn requirements may be beneficial. Several opportunities exist to utilize and improve understanding of Zn associations with prostate health and disease.

The AdcACB/AdcAII system is essential for zinc homeostasis and an important contributor of Enterococcus faecalis virulence

Bacterial pathogens require a variety of micronutrients for growth, including trace metals such as iron, manganese, and zinc (Zn). Despite their relative abundance in host environments, access to these metals is severely restricted during infection due to host-mediated defense mechanisms collectively known as nutritional immunity. Despite a growing appreciation of the importance of Zn in host-pathogen interactions, the mechanisms of Zn homeostasis and the significance of Zn to the pathophysiology of E. faecalis, a major pathogen of nosocomial and community-associated infections, have not been thoroughly investigated. Here, we show that E. faecalis encoded ABC-type transporter AdcACB and an orphan substrate-binding lipoprotein AdcAII that work cooperatively to maintain Zn homeostasis. Simultaneous inactivation of adcA and adcAII or the entire adcACB operon led to a significant reduction in intracellular Zn under Zn-restricted conditions and heightened sensitivity to Zn-chelating agents including human calprotectin, aberrant cell morphology, and impaired fitness in serum ex vivo. Additionally, inactivation of adcACB and adcAII significantly reduced bacterial tolerance toward cell envelope-targeting antibiotics. Finally, we showed that the AdcACB/AdcAII system contributes to E. faecalis virulence in a Galleria mellonella invertebrate infection model and in two catheter-associated mouse infection models that recapitulate many of the host conditions associated with enterococcal human infections. Collectively, this report reveals that high-affinity Zn import is important for the pathogenesis of E. faecalis establishing the surface-associated AdcA and AdcAII lipoproteins as potential therapeutic targets.

Insights into the kinetic regulation of Zn bioaccumulation at trace levels: Lighting up Saccharomycescerevisiae

Zn displays a double-edged effect by acting both as a micronutrient and a toxic metal, and quantitative analysis of its kinetic flux under low environmental concentrations is critical to understand its intracellular regulation. In the present study, we employed a Zn sensitive model eukaryote, the yeast Saccharomyces cerevisiae, which responded to intracellular Zn levels by increasing its autofluorescence, to quantify Zn influx, transportation between labile and storage pools, and efflux under different Zn exposure levels (<1 μM). We demonstrated that the yeast regulated Zn uptake from the extracellular source by a gradually decreased accumulation following an initial high accumulation rate. The subsequent reduced accumulation rate resulted in a steady-state Zn accumulation at 0.061 and 0.073 μg Zn/μg P as the threshold values for the control yeast and Zn-depleted yeast, respectively, independently of the extracellular Zn concentration. Compared with the control yeast, the Zn-depleted yeast possessed a higher accumulation rate, but the difference of bioaccumulation was maintained at approximately 0.01 μg Zn/μg P under different concentrations of extracellular Zn. In contrast, transportation between labile Zn and storage Zn pools or Zn efflux to the extracellular environment was not obvious after Zn exposure, indicating that the Zn dose was below a basal requirement. Such stabilized Zn accumulation was only induced by controlling the Zn influx at the bio-interface. With the novel monitoring of the kinetic changes of autofluorescence, our study demonstrated a remarkably tight Zn regulation system in yeast, providing enlightenment for Zn homeostasis in eukaryotes under low Zn exposure in aqueous environments.

Dietary zinc restriction affects the expression of genes related to immunity and stress response in the small intestine of pigs

Zinc (Zn) is an essential mineral and its deficiency manifests in non-specific clinical signs that require long time to develop. The response of swine intestine to Zn restriction was evaluated to identify early changes that can be indicative of Zn deficiency. Twenty-seven pigs (body weight = 77⋅5 ± 2⋅5 kg) were assigned to one of three diets: diet without added Zn (Zn-restricted diet, ZnR), and ZnR-supplemented with either 50 (Zn50) or 100 mg of Zn/kg of diet (Zn100) of Zn supplied by ZnCl₂. After 32 d consuming the diets, serum Zn concentration in ZnR pigs was below the range of 0⋅59-1⋅37 μg/ml considered sufficient, thereby confirming subclinical Zn deficiency. Pigs showed no obvious health or growth changes. RNA-seq analysis followed by qPCR showed decreased expression of metallothionein-1 (MT1) (P < 0⋅05) and increased expression of Zn transporter ZIP4 (P < 0⋅05) in jejunum and ileum of ZnR pigs compared with Zn-supplemented pigs. Ingenuity pathway analysis revealed that Zn50 and Zn100 induced changes in genes related to nucleotide excision repair and integrin signalling pathways. The top gene network in the ZnR group compared with Zn100 was related to lipid and drug metabolism; and compared with Zn50, was related to cellular proliferation, assembly and organisation. Dietary Zn concentrations resulted in differences in genes related to immune pathways. Our analysis showed that small intestine presents changes associated with Zn deficiency after 32 d of Zn restriction, suggesting that the intestine could be a sentinel organ for Zn deficiency.

Association between toxic and essential metals in blood and global DNA methylation among electronic waste workers in Agbogbloshie, Ghana

Aberrant global DNA methylation status is a known biomarker for increased disease risk, especially cancer. There is little published data on the association between toxic and essential metal mixtures and global DNA methylation in electronic waste (e-waste) workers. We aimed to establish the association between toxic and essential metals in blood and the effect of their interactions on global DNA methylation among e-waste recyclers and a reference group in Ghana. We used ICP-MS to measure the level of five metals (Se, Zn, Mn, Cd, and Pb) in the blood of 100 e-waste workers and 51 controls. We quantified blood DNA methylation levels of LINE-1 as an indicator of global DNA methylation. Cd, Mn, and Se levels were significantly higher in the reference group than in e-waste workers. Only Pb was significantly higher in the e-waste workers compared to the controls. Our linear regression analysis results showed a significant inverse association between Zn and LINE-1 DNA methylation (β_Zn =  - 0.912; 95% CI, - 1.512, - 0.306; p = 0.003) which corresponds to a 0.009 decrease in %LINE-1 methylation (95% CI, - 0.015, - 0.003; p = 0.003) for a 1% increase in Zn concentration. Potential interactions between Cd and Zn on global DNA methylation were observed. In summary, co-exposure to toxic and essential metals is associated with global (LINE-1) DNA methylation.

Design of a Highly Selective Benzimidazole-Based Derivative for Optical and Solid-State Detection of Zinc Ion

A novel series of benzimidazole-based molecules mimicking biological receptors, which exhibit selective coordination with zinc ions, were designed and synthesized. The photochromic behavior of these derivatives with various metal ions suggests a selective interaction of one of the receptors 2-(pyridin-2-yl)-4,7-di(thiophen-2-yl)-3H-benzo[d]imidazole (2c) with zinc ion. The lower limit of detection by photoluminescence quenching was determined to be 16 nM. The mechanism of selective complexation was elucidated by ¹H nuclear magnetic resonance titrations and dynamic light scattering analysis. The stoichiometry of the formation of the Zn(2c)₂ complex was evaluated by single-crystal X-ray diffraction and mass spectral techniques and calculated to be 2:1 (L:M). A change in the electronic energy levels on the sensor analyte interaction was observed by both ultraviolet photoelectron spectroscopy analysis and by density functional theory calculations, suggesting an electroactive semiconductor behavior. A symmetric Schottky structured sensor device was fabricated using the receptor 2c as the active sensing layer. A distinct change in current-voltage characteristics between the receptor and the complex suggests that the fabricated device could be used as a solid-state sensor for detecting zinc ion.

Blood Trace Element Status in Camels: A Review

Trace minerals play an important role in animal health and productivity. They are involved also in many physiological activities, and their deficiency causes a variety of pathological problems and metabolic defects, reducing consequently the animal productivity. The demand for animal products in semi-arid areas is rapidly increasing, and the supply is still below the required level, partially due to low animal productivity. Camels (Camelus dromedarius and Camelus bactrianus) are considered one of the main sources of healthy, high-quality meat and milk for human consumption within most of the countries in the semi-arid regions. Despite their efficient adaptation to their environment, camels can suffer from the growth retardation of newborns, low feed efficiency, anemia, poor fertility, poor reproduction and many other metabolic disorders. It is well known that trace mineral deficiencies and trace mineral toxicities can influence camels' production and reproductive efficiency, as well as many aspects of their growth and metabolism. Evaluating the trace minerals status of camels and their variability is an obvious step toward improving camels' productivity and health. Thus, the present article reviews the data regarding the status of trace minerals (copper, zinc, iron, selenium, manganese, cobalt, iodine, fluorine, molybdenum, sulfur, bromide and nickel) in camel blood and their physiological variability, with a focus on their deficiency and toxicity effects.

Reference cut-offs to define low serum zinc concentrations in healthy 1-19 year old Indian children and adolescents

BACKGROUND/OBJECTIVES

Population zinc (Zn) status assessment is based on serum zinc concentration (SZC) cut-offs defined by the International Zinc Nutrition Consultative Group (IZiNCG). The objective of this study is to derive reference SZC cut-offs in apparently healthy 1-19 year Indian children and adolescents using comprehensive national nutrition survey (CNNS) data, and to measure the prevalence of Zn deficiency.

SUBJECTS/METHODS

Apparently healthy children (n = 12,473) were selected from the CNNS, by including the highest 2 wealth quintiles, and excluding stunted, thin and obese children, and those with CRP > 5 mg/L, anaemia, hypo-albuminemia, diabetes, recent diarrhoea and history of smoking. The 2.5th centile of age-based distributions defined the SZC cut-offs, used to measure the prevalence of Zn deficiency in India, as against the IZiNCG cut-offs.

RESULTS

The present study SZC cut-offs were significantly lower, by 10-18 µg/dL, than the IZiNCG cut-offs; more in adolescents. Prevalence of Zn deficiency in the entire CNNS, with these cut-offs, was 2.7 (<10 years) to 5.5 (10-19 years) times lower than with the IZiNCG cut-offs. No geographical state, nor any age group, had Zn deficiency as a serious public health problem (≥20%). In contrast, with IZiNCG cut-offs, 9-27 states (depending on age group) had a public health problem.

CONCLUSIONS

The present study reference SZC cut-offs for Zn deficiency are lower than the IZiNCG cut-offs, and their rigorous selection from a national sample makes them more appropriate for use in India. A re-examination of the global applicability of IZiNCG recommended cut-offs in other LMICs appears appropriate.

Lipoic Acid Restores Binding of Zinc Ions to Human Serum Albumin

Human serum albumin (HSA) is the main zinc(II) carrier in blood plasma. The HSA site with the strongest affinity for zinc(II), multi-metal binding site A, is disrupted by the presence of fatty acids (FAs). Therefore, the FA concentration in the blood influences zinc distribution, which may affect both normal physiological processes and a range of diseases. Based on the current knowledge of HSA’s structure and its coordination chemistry with zinc(II), we investigated zinc interactions and the effect of various FAs, including lipoic acid (LA), on the protein structure, stability, and zinc(II) binding. We combined NMR experiments and isothermal titration calorimetry to examine zinc(II) binding to HSA at a sub-atomic level in a quantitative manner as well as the effect of FAs. Free HSA results indicate the existence of one high-affinity zinc(II) binding site and multiple low-affinity sites. Upon the binding of FAs to HSA, we observed a range of behaviors in terms of zinc(II) affinity, depending on the type of FA. With FAs that disrupt zinc binding, the addition of LA restores HSA’s affinity for zinc ions to the levels seen with free defatted HSA, indicating the possible mechanism of LA, which is effective in the treatment of diabetes and cardiovascular diseases.

The Impact of Zinc and Zinc Homeostasis on the Intestinal Mucosal Barrier and Intestinal Diseases

Zinc is an essential trace element for living organisms, and zinc homeostasis is essential for the maintenance of the normal physiological functions of cells and organisms. The intestine is the main location for zinc absorption and excretion, while zinc and zinc homeostasis is also of great significance to the structure and function of the intestinal mucosal barrier. Zinc excess or deficiency and zinc homeostatic imbalance are all associated with many intestinal diseases, such as IBD (inflammatory bowel disease), IBS (irritable bowel syndrome), and CRC (colorectal cancer). In this review, we describe the role of zinc and zinc homeostasis in the intestinal mucosal barrier and the relevance of zinc homeostasis to gastrointestinal diseases.

Albumin-corrected Zn and available free Zn-binding capacity as indicators of Zn status - potential for clinical implementation

We have established and describe two measurement procedures to diagnose possible zinc (Zn) deficiency; albumin-corrected Zn concentration and available free Zn-binding capacity. Reference intervals for both biomarkers were established in healthy adults from the Danish population. The clinical usefulness of the measurement procedures was investigated in patients with cirrhosis and in patients given parenteral nutrition due to short bowel syndrome. The results of both methods indicate that there is a risk of overdiagnosing Zn deficiency based on low plasma Zn concentrations. Needless Zn supplementation may thus be avoided by using the albumin-corrected Zn concentration or available free Zn-binding capacity.

Impact of Zinc Transport Mechanisms on Embryonic and Brain Development

The trace element zinc (Zn) binds to over ten percent of proteins in eukaryotic cells. Zn flexible chemistry allows it to regulate the activity of hundreds of enzymes and influence scores of metabolic processes in cells throughout the body. Deficiency of Zn in humans has a profound effect on development and in adults later in life, particularly in the brain, where Zn deficiency is linked to several neurological disorders. In this review, we will summarize the importance of Zn during development through a description of the outcomes of both genetic and early dietary Zn deficiency, focusing on the pathological consequences on the whole body and brain. The epidemiology and the symptomology of Zn deficiency in humans will be described, including the most studied inherited Zn deficiency disease, Acrodermatitis enteropathica. In addition, we will give an overview of the different forms and animal models of Zn deficiency, as well as the 24 Zn transporters, distributed into two families: the ZIPs and the ZnTs, which control the balance of Zn throughout the body. Lastly, we will describe the TRPM7 ion channel, which was recently shown to contribute to intestinal Zn absorption and has its own significant impact on early embryonic development.

Zinc and its role in vitamin D function

Zinc is an essential mineral with an important relationship with vitamin D. Studies have found that reduced blood zinc levels could predict vitamin D deficiency in adolescent girls, while zinc supplementation increased vitamin D levels in postmenopausal women. In vitro studies using human peritoneal macrophages have found that zinc induced the release of calcitriol (1,25-dihydroxycholecalciferol). Zinc also acts as a cofactor for vitamin D functions, as the transcriptional activity of vitamin D-dependent genes relies on zinc to exert pleiotropic functions, including mineral ion regulation. Vitamin D could also induce zinc transporters to regulate zinc homeostasis. Together, zinc and vitamin D in adequate concentrations help maintain a healthy musculoskeletal system and beyond; however, deficiency in either of these nutrients can result in various disorders affecting almost all body systems. This brief article will focus on the role of zinc in vitamin D functions.