Contribution of Zinc and Zinc Transporters in the Pathogenesis of Inflammatory Bowel Diseases

A Comprehensive Review of the Triangular Relationship among Diet-Gut Microbiota-Inflammation

The human gastrointestinal tract hosts a complex and dynamic community of microorganisms known as the gut microbiota, which play a pivotal role in numerous physiological processes, including digestion, metabolism, and immune function. Recent research has highlighted the significant impact of diet on the gut microbiota composition and functionality, and the consequential effects on host health. Concurrently, there is growing evidence linking the gut microbiota to inflammation, a key factor in many chronic diseases such as inflammatory bowel disease (IBD), obesity, diabetes, and cardiovascular diseases (CVDs). This review explores how dietary components influence the gut microbiota composition, how these microbial changes affect inflammatory pathways, and the therapeutic implications of modulating this axis for chronic inflammatory disease prevention and management. Beneficial dietary patterns, such as the Mediterranean diet (MD) and plant-based diets, promote a diverse and balanced gut microbiota composition, supporting anti-inflammatory pathways. Conversely, the Western diet (WD), high in saturated fats and refined sugars, is associated with dysbiosis and increased inflammation. With all the links between the three variables considered, this review attempts to offer a thorough examination of the triangle formed by inflammation, the gut microbiota, and food.

Protective effect of zinc gluconate on intestinal mucosal barrier injury in antibiotics and LPS-induced mice

Objective

The aim of the study is to investigate the function and mechanism of Zinc Gluconate (ZG) on intestinal mucosal barrier damage in antibiotics and Lipopolysaccharide (LPS)-induced mice.

Methods

We established a composite mouse model by inducing intestinal mucosal barrier damage using antibiotics and LPS. The animals were divided into five groups: Control (normal and model) and experimental (low, medium, and high-dose ZG treatments). We evaluated the intestinal mucosal barrier using various methods, including monitoring body weight and fecal changes, assessing pathological damage and ultrastructure of the mouse ileum, analyzing expression levels of tight junction (TJ)-related proteins and genes, confirming the TLR4/NF-κB signaling pathway, and examining the structure of the intestinal flora.

Results

In mice, the dual induction of antibiotics and LPS led to weight loss, fecal abnormalities, disruption of ileocecal mucosal structure, increased intestinal barrier permeability, and disorganization of the microbiota structure. ZG restored body weight, alleviated diarrheal symptoms and pathological damage, and maintained the structural integrity of intestinal epithelial cells (IECs). Additionally, ZG reduced intestinal mucosal permeability by upregulating TJ-associated proteins (ZO-1, Occludin, Claudin-1, and JAM-A) and downregulating MLCK, thereby repairing intestinal mucosal barrier damage induced by dual induction of antibiotics and LPS. Moreover, ZG suppressed the TLR4/NF-κB signaling pathway, demonstrating anti-inflammatory properties and preserving barrier integrity. Furthermore, ZG restored gut microbiota diversity and richness, evidenced by increased Shannon and Observed features indices, and decreased Simpson's index. ZG also modulated the relative abundance of beneficial human gut bacteria (Bacteroidetes, Firmicutes, Verrucomicrobia, Parabacteroides, Lactobacillus, and Akkermansia) and harmful bacteria (Proteobacteria and Enterobacter), repairing the damage induced by dual administration of antibiotics and LPS.

Conclusion

ZG attenuates the dual induction of antibiotics and LPS-induced intestinal barrier damage and also protects the intestinal barrier function in mice.

Intestinal inflammation marker calprotectin regulates epithelial intestinal zinc metabolism and proliferation in mouse jejunal organoids

Calprotectin (CP), a heterodimer of S100A8 and S100A9, is expressed by neutrophils and a number of innate immune cells and is used widely as a marker of inflammation, particularly intestinal inflammation. CP is a ligand for toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE). In addition, CP can act as a microbial modulatory agent via a mechanism termed nutritional immunity, depending on metal binding, most notably Zn2+. The effects on the intestinal epithelium are largely unknown. In this study we aimed to characterize the effect of calprotectin on mouse jejunal organoids as a model epithelium, focusing on Zn2+ metabolism and cell proliferation. CP addition upregulated the expression of the Zn2+ absorptive transporter Slc39a4 and of methallothionein Mt1 in a Zn2+-sensitive manner, while downregulating the expression of the Zn2+ exporter Slc30a2 and of methallothionein 2 (Mt2). These effects were greatly attenuated with a CP variant lacking the metal binding capacity. Globally, these observations indicate adaptation to low Zn2+ levels. CP had antiproliferative effects and reduced the expression of proliferative and stemness genes in jejunal organoids, effects that were largely independent of Zn2+ chelation. In addition, CP induced apoptosis modestly and modulated antimicrobial gene expression. CP had no effect on epithelial differentiation. Overall, CP exerts modulatory effects in murine jejunal organoids that are in part related to Zn2+ sequestration and partially reproduced in vivo, supporting the validity of mouse jejunal organoids as a model for mouse epithelium.

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.

Engineered baicalein-decorated zinc phosphates for synergistic alleviation of inflammatory bowel disease by repairing the mucosal barrier and relieving oxidative stress

Orally administered baicalein-decorated zinc phosphates (ZnBM) were engineered for mucosal barrier improvement and intestinal inflammation relief. ZnBM with a size of 1.78 μm comprised 5.58 wt% baicalein and 13.17 wt% zinc. The incorporation of baicalein endowed ZnBM with excellent radical scavenging activities. ZnBM exhibited good stability with negligible zinc release in PBS solution for 2 days, and 32.82% of the zinc could reach the gut. In addition, ZnBM polarized macrophages into the anti-inflammatory M2 type and effectively scavenged intracellular reactive oxygen species (ROS) of lipopolysaccharide (LPS)-treated RAW264.7. Meanwhile, ZnBM effectively scavenged intracellular ROS of phorbol 12-myristate 13-acetate (PMA)-induced Caco-2 cells and exerted a reparative effect on the LPS-damaged Caco-2 monolayer, causing an obvious improvement of the barrier function. Reduced systemic exposure to FITC-dextran was observed to illustrate barrier restoration by ZnBM, which was achieved through upregulation of tight junction protein expression. Notably, the commonly used clinical drug 5-aminosalicylic acid is toxic to the liver and kidneys, and commercial ZnO caused the death of mice during treatment. Apparently, the therapeutic effect of ZnBM was significantly better than that of baicalein alone in chronic colitis. Overall, ZnBM exhibited outstanding therapeutic efficacy and is expected to treat colitis due to its effectiveness, biosecurity, facile preparation, and easy storage.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Aryl hydrocarbon receptor utilises cellular zinc signals to maintain the gut epithelial barrier

Zinc and plant-derived ligands of the aryl hydrocarbon receptor (AHR) are dietary components affecting intestinal epithelial barrier function. Here, we explore whether zinc and the AHR pathway are linked. We show that dietary supplementation with an AHR pre-ligand offers protection against inflammatory bowel disease in a mouse model while protection fails in mice lacking AHR in the intestinal epithelium. AHR agonist treatment is also ineffective in mice fed zinc depleted diet. In human ileum organoids and Caco-2 cells, AHR activation increases total cellular zinc and cytosolic free Zn2+ concentrations through transcription of genes for zinc importers. Tight junction proteins are upregulated through zinc inhibition of nuclear factor kappa-light-chain-enhancer and calpain activity. Our data show that AHR activation by plant-derived dietary ligands improves gut barrier function at least partly via zinc-dependent cellular pathways, suggesting that combined dietary supplementation with AHR ligands and zinc might be effective in preventing inflammatory gut disorders.

Effects of Daily Zinc Alone or in Combination with Other Nutrient Supplements on the Risk of Malaria Parasitaemia: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Zinc supplementation has been explored as a potential intervention to reduce the risk of malaria parasitaemia in randomised controlled trials (RCTs). However, inconsistent evidence has been obtained regarding the efficacy of zinc supplementation in the context of malaria prevention. This systematic review was implemented to survey the existing literature to determine the effects of the daily oral administration of zinc, either alone or in combination with other nutrient supplements, on the risk of malaria parasitaemia. The systematic review was prospectively registered in the PROSPERO database CRD42023424345 and followed PRISMA protocols. A comprehensive search was conducted across multiple databases, including Embase, MEDLINE, Ovid, PubMed, Scopus, ProQuest, and Google Scholar, from their inception until 6 May 2023. The risk of bias in RCTs was assessed using the Cochrane Risk of Bias Tool 2 (RoB 2). The effect sizes, represented as risk ratios (RRs) with 95% confidence intervals (CIs), were standardised by transforming them into log RRs and then pooling them using a fixed-effects or random-effects model depending on the heterogeneity across studies. Comparisons were made between individuals who received zinc alone or zinc in combination with other micronutrient supplements and those who did not receive zinc. A total of 1339 articles were identified through the database searches, and after the screening and selection process, 10 studies were included in the final synthesis. The meta-analysis revealed that zinc supplementation alone did not significantly affect the risk of malaria parasitaemia compared with placebo (p = 0.30, log RR = 0.05, 95% CI: -0.05-0.15, I² = 0.00%, with 566 malaria cases in the zinc intake group and 521 malaria cases in the placebo group). However, the analysis demonstrated a borderline significant effect of zinc supplementation in combination with other micronutrients on the risk of malaria parasitaemia compared with placebo (p = 0.05, log RR = 1.31, 95% CI: 0.03-2.59, I² = 99.22%, with 8904 malaria cases in the zinc intake group and 522 malaria cases in the placebo group). The findings of this systematic review indicate that zinc supplementation, either alone or combined with the supplementation of other micronutrients such as vitamin A, iron, or multiple nutrients, does not significantly alter the risk of malaria parasitaemia. Further research with larger sample sizes is warranted to explore the potential effects of multi-nutrient supplementation and to identify more specific micronutrients and additional factors associated with the risk of malaria, rather than just zinc alone, among individuals in different malaria-endemic areas.

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.

Boswellic acid coated zinc nanoparticles attenuate NF-κB-mediated inflammation in DSS-induced ulcerative colitis in rats

INTRODUCTION

Ulcerative colitis (UC) is a chronic non-specific inflammatory bowel disease, and until now therapeutic agents for UC still cannot exert satisfied effects. Therefore, this study aimed to investigate the ameliorative effect of boswellic acid coated zinc nanoparticles (BAs-ZnNPs) on dextran sodium sulphate (DSS) induced-UC in rats.

METHODS

Rats were divided into five groups; control, BAs-ZnNPs, DSS, DSS+BAs, and DSS + BAs-ZnNPs. The activity of alkaline phosphatase (ALP) was determined colorimetrically, while the concentration of IgM, IgG, TNF-α, IL-1β, and IL-8 were measured by ELISA. Levels of gene expression of NF-κB and COX-2 genes were evaluated by RT-qPCR, while the expression of protein levels of PI3K and STAT-3 were done by western blotting. Finally, histopathological examination of colon tissues of different groups of rats was done.

RESULTS

The depicted ball-like structure of the BAs-ZnNPs in the TEM images ranging in size from 50 to 100 nm in diameter while their formation was confirmed by UV-visible spectroscopy with a sharp peak of maximum absorbance at 266 nm. Our results revealed that BAs-ZnNPs exerted an anti-inflammatory effect in the experimental model of colitis, demonstrated histologically and biochemically as shown by the improvement of ALP, IgM, IgG, and the gene expression levels of NF-κB and COX-2. Also, this beneficial effect was associated with the reduction in the expression of TNF-α, IL-1β, IL-8, PI3K, and STAT-3. Thus, this effect improves the altered immune response associated with the colonic inflammation.

CONCLUSION

BAs-ZnNPs can be proposed as a therapeutic candidate to attenuate UC. The potential underlying mechanism includes suppression of ALP, IgM, IgG, IL-1β, and IL-8 levels via regulation of NF-κB and COX-2 gene expression and STAT-3 and PI3K protein expression in a UC rat model.

Anti-inflammatory mechanisms of polyphenols in adipose tissue: role of gut microbiota, intestinal barrier integrity and zinc homeostasis

Obesity is associated with an imbalance of micro-and macro-nutrients, gut dysbiosis, and a "leaky" gut phenomenon. Polyphenols, such as curcumin, resveratrol, and anthocyanins may alleviate the systemic effects of obesity, potentially by improving gut microbiota, intestinal barrier integrity (IBI), and zinc homeostasis. The essential micronutrient zinc plays a crucial role in the regulation of enzymatic processes, including inflammation, maintenance of the microbial ecology, and intestinal barrier integrity. In this review, we focus on IBI- which prevents intestinal lipopolysaccharide (LPS) leakage - as a critical player in polyphenol-mediated protective effects against obesity-associated white adipose tissue (WAT) inflammation. This occurs through mechanisms that block the movement of the bacterial endotoxin LPS across the gut barrier. Available research suggests that polyphenols reduce WAT and systemic inflammation via crosstalk with inflammatory NF-κB, the mammalian target of rapamycin (mTOR) signaling and zinc homeostasis.

The role of gut microbiota in liver regeneration

The liver has unique regeneration potential, which ensures the continuous dependence of the human body on hepatic functions. As the composition and function of gut microbiota has been gradually elucidated, the vital role of gut microbiota in liver regeneration through gut-liver axis has recently been accepted. In the process of liver regeneration, gut microbiota composition is changed. Moreover, gut microbiota can contribute to the regulation of the liver immune microenvironment, thereby modulating the release of inflammatory factors including IL-6, TNF-α, HGF, IFN-γ and TGF-β, which involve in different phases of liver regeneration. And previous research have demonstrated that through enterohepatic circulation, bile acids (BAs), lipopolysaccharide, short-chain fatty acids and other metabolites of gut microbiota associate with liver and may promote liver regeneration through various pathways. In this perspective, by summarizing gut microbiota-derived signaling pathways that promote liver regeneration, we unveil the role of gut microbiota in liver regeneration and provide feasible strategies to promote liver regeneration by altering gut microbiota composition.

Functions of the Zinc-Sensing Receptor GPR39 in Regulating Intestinal Health in Animals

G protein-coupled receptor 39 (GPR39) is a zinc-sensing receptor (ZnR) that can sense changes in extracellular Zn2+, mediate Zn2+ signal transmission, and participate in the regulation of numerous physiological activities in living organisms. For example, GPR39 activates the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and phosphatidylinositol3-kinase/protein kinase B (PI3K/AKT) signaling pathways upon Zn2+ stimulation, enhances the proliferation and differentiation of colonic cells, and regulates ion transport, as well as exerting other functions. In recent years, with the increased attention to animal gut health issues and the intensive research on GPR39, GPR39 has become a potential target for regulating animal intestinal health. On the one hand, GPR39 is involved in regulating ion transport in the animal intestine, mediating the Cl− efflux by activating the K+/Cl− synergistic protein transporter, and relieving diarrhea symptoms. On the other hand, GPR39 can maintain the homeostasis of the animal intestine, promoting pH restoration in colonic cells, regulating gastric acid secretion, and facilitating nutrient absorption. In addition, GPR39 can affect the expression of tight junction proteins in intestinal epithelial cells, improving the barrier function of the animal intestinal mucosa, and maintaining the integrity of the intestine. This review summarizes the structure and signaling transduction processes involving GPR39 and the effect of GPR39 on the regulation of intestinal health in animals, with the aim of further highlighting the role of GPR39 in regulating animal intestinal health and providing new directions and ideas for studying the prevention and treatment of animal intestinal diseases.

Effects of Dietary Nutrients on Fatty Liver Disease Associated With Metabolic Dysfunction (MAFLD): Based on the Intestinal-Hepatic Axis

Non-alcoholic fatty liver disease (NAFLD) has recently become the most common liver disease with a global prevalence of over 25% and is expected to increase. Recently, experts have reached a consensus that “fatty liver disease associated with metabolic dysfunction or MAFLD” may be a more appropriate and inclusive definition than NAFLD. Like the former name NAFLD, MAFLD, as a manifestation of multiple system metabolic disorders involving the liver, has certain heterogeneity in its pathogenesis, clinical manifestations, pathological changes and natural outcomes. We found that there is a delicate dynamic balance among intestinal microflora, metabolites and host immune system to maintain a healthy intestinal environment and host health. On the contrary, this imbalance is related to diseases such as MAFLD. However, there are no clear studies on how dietary nutrients affect the intestinal environment and participate in the pathogenesis of MAFLD. This review summarizes the interactions among dietary nutrients, intestinal microbiota and MAFLD in an attempt to provide evidence for the use of dietary supplements to regulate liver function in patients with MAFLD. These dietary nutrients influence the development and progression of MAFLD mainly through the hepatic-intestinal axis by altering dietary energy absorption, regulating bile acid metabolism, changing intestinal permeability and producing ethanol. Meanwhile, the nutrients have the ability to combat MAFLD in terms of enriching abundance of intestinal microbiota, reducing Firmicutes/Bacteroidetes ratio and promoting abundance of beneficial gut microbes. Therefore, family therapy with MAFLD using a reasonable diet could be considered.

Insights into Health-Promoting Effects of Plant MicroRNAs: A Review

Plant-derived microRNAs (miRNAs) play a significant role in human health and are "dark nutrients", as opposed to traditional plant nutrients, as well as important components of food diversification. Studies have revealed that multiple plant-derived miRNA pathways affect human health. First, plant miRNAs regulate plant growth and development and accumulation of metabolites, which alters the food quality and thus indirectly interferes with the health of the host. Moreover, when absorbed in vivo, some miRNAs may target the host cell mRNAs to affect protein expression. In addition, plant miRNAs target and reshape the human gut microbiota (GM), which interferes with the physiology and metabolism of the host. Therefore, miRNAs play a significant role in the cross-kingdom communication of plants, GM, and the host and in maintaining a balance of the three. Future contributions of plant miRNAs can bring new perspectives and opportunities to better understand food nutrition and health care research, which will facilitate the right exploitation of plant resources.

The effect of zinc-biofortified rice on zinc status of Bangladeshi preschool children: a randomized, double-masked, household-based, controlled trial

BACKGROUND

Zinc biofortification of rice could sustainably improve zinc status in countries where zinc deficiency is common and rice is a staple, but its efficacy has not been tested. Fatty acid desaturases (FADS) are putative new zinc status biomarkers.

OBJECTIVES

Our objective was to test the efficacy of zinc-biofortified rice (BFR) in preschool-aged children with zinc deficiency. Our hypothesis was that consumption of BFR would increase plasma zinc concentration (PZC).

METHODS

We conducted a 9-mo, double-masked intervention trial in 12-36-mo-old rural Bangladeshi children, most of whom were zinc-deficient (PZC <70 µg/dL) and stunted (n = 520). The children were randomly assigned to receive either control rice (CR) or BFR provided in cooked portions to their households daily, with compliance monitoring. The primary outcome was PZC. Secondary outcomes were zinc deficiency, linear growth, infection-related morbidity, FADS activity indices, intestinal fatty acid binding protein (I-FABP) and fecal calprotectin. We applied sparse serial sampling for midpoint measures and analyzed data by intention-to-treat using mixed-effects models.

RESULTS

At baseline, median (IQR) PZC was 60.4 (56.3-64.3) µg/dL, 78.1% of children were zinc deficient, and 59.7% were stunted. Mean ± SD daily zinc intakes from the CR and BFR during the trial were 1.20 ± 0.34 and 2.22 ± 0.47 mg/d, respectively (P < 0.001). There were no significant time-by-treatment effects on PZC, zinc deficiency prevalence, FADS activity, I-FABP, or fecal calprotectin (all P > 0.05). There was a time-treatment interaction for height-for-age z-scores (P < 0.001) favoring the BFR group. The morbidity longitudinal prevalence ratio was 1.08 (95% CI: 1.05, 1.12) comparing the BFR and CR groups, due to more upper respiratory tract illness in the BFR group.

CONCLUSIONS

Consumption of BFR for 9 mo providing ∼1 mg of additional zinc daily to Bangladeshi children did not significantly affect PZC, prevalence of zinc deficiency, or FADS activity.The trial was registered at clinicaltrials.gov as NCT03079583.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

A folliculocentric perspective of dandruff pathogenesis: Could a troublesome condition be caused by changes to a natural secretory mechanism?

Dandruff is a common scalp condition, which frequently causes psychological distress in those affected. Dandruff is considered to be caused by an interplay of several factors. However, the pathogenesis of dandruff remains under-investigated, especially with respect to the contribution of the hair follicle. As the hair follicle exhibits unique immune-modulatory properties, including the creation of an immunoinhibitory, immune-privileged milieu, we propose a novel hypothesis taking into account the role of the hair follicle. We hypothesize that the changes and imbalance of yeast and bacterial species, along with increasing proinflammatory sebum by-products, leads to the activation of immune response and inflammation. Hair follicle keratinocytes may then detect these changes in scalp microbiota resulting in the recruitment of leukocytes to the inflammation site. These changes in the scalp skin immune-microenvironment may impact hair follicle immune privilege status, which opens new avenues into exploring the role of the hair follicle in dandruff pathogenesis. Also see the video abstract here: https://youtu.be/mEZEznCYtNs.

Therapeutic supplementation with zinc in the management of COVID-19-related diarrhea and ageusia/dysgeusia: mechanisms and clues for a personalized dosage regimen

Zinc supplementation is indicated for diarrhea and taste disorders, which are both features of COVID-19. Nevertheless, this strategy has not been tested for the treatment of these secondary complications in the current pandemic. Through an updated review, a practical appraisal was considered as a means of providing a medical nexus of therapeutic zinc regimens as an adjunct in the management of COVID-19–related diarrhea and ageusia/dysgeusia. While diarrhea and taste disorders are consequences of COVID-19, zinc supplementation is useful for non–COVID-19 patients with these clinical problems. The overwhelming evidence for supplementing with zinc in diarrhea and pneumonia is associated with the treatment of children, while for taste disorders the use of supplementing with zinc is more examined in adults. Whereas COVID-19 is more prevalent in adults, precautions should be exercised not to translate the zinc dosage used for children with diarrhea and taste disorders into the current pandemic. Therapeutic doses of zinc used for adults (∼50–150 mg/day of elemental zinc) could be included in the treatment strategies for COVID-19, but this proposal should be examined through randomized studies.

Immunonutrition effects on coping with COVID-19

COVID-19 implications are still a threat to global health. In the face of this pandemic, food and nutrition are key issues that can boost the immune system. The bioactivity of functional foods and nutrients (probiotics, prebiotics, water- and fat-soluble vitamins, minerals, flavonoids, glutamine, arginine, nucleotides, and PUFAs) contributes to immune system modulation, which establishes the status of nutrients as a factor of immune competence. These foods can contribute, especially during a pandemic, to the minimization of complications of SARS-CoV-2 infection. Therefore, it is important to support the nutritional strategies for strengthening the immune status, associated with good eating habits, as a way to confront COVID-19.

Zinc is an important inter-kingdom signal between the host and microbe

Zinc (Zn) is an essential trace element in living organisms and plays a vital role in the regulation of both microbial virulence and host immune responses. A growing number of studies have shown that zinc deficiency or the internal Zn concentration does not meet the needs of animals and microbes, leading to an imbalance in zinc homeostasis and intracellular signalling pathway dysregulation. Competition for zinc ions (Zn²⁺) between microbes and the host exists in the use of Zn²⁺ to maintain cell structure and physiological functions. It also affects the interplay between microbial virulence factors and their specific receptors in the host. This review will focus on the role of Zn in the crosstalk between the host and microbe, especially for changes in microbial pathogenesis and nociceptive neuron-immune interactions, as it may lead to new ways to prevent or treat microbial infections.

The Prevalence of Zinc Deficiency in Crohn's Disease Patients

Objective: Zinc is a trace element, which has been related to inflammatory diseases such as inflammatory bowel disease (IBD). We aimed to evaluate the serum zinc levels in Iranian patients with Crohn's disease (CD). Materials and methods:The present study was conducted on 65 CD patients and 65 healthy controls. Serum zinc levels were measured in both patients and controls and compared by age, sex, and site of inflammation between groups. Results: Mean serum zinc level in the study population was 86.2±17.0 ng/dL. The serum zinc level was 88.1±16.7 ng/dL in CD patients and 86.2±17.0 ng/dL in the control group. The difference between groups was not statistically significant (P=0.191). No significant differences were observed in serum zinc levels of males and females (P=0.087). Zinc deficiency was observed in 21.5% and 7.7% of cases and controls, respectively. Compared to the control group, low serum zinc levels were significantly higher in CD patients (P=0.025). Regarding the site of inflammation, neither the concentration of serum zinc (P=0.058) nor zinc deficiency prevalence (P=0.864) were significantly different in cases compared to controls. Conclusion: The prevalence of zinc deficiency was higher in CD patients compared to controls. However, serum zinc concentrations were not significantly different between groups. Age, sex, and site of inflammation were not found to be predictors of zinc deficiency. Evaluating the zinc status of CD patients for possible supplementation in cases of deficiency is recommended.

Metallothionein-3 is a clinical biomarker for tissue zinc levels in nasal mucosa

OBJECTIVE

Recently, depleted tissue zinc levels were found in nasal mucosa from patients with chronic rhinosinusitis (CRS) in correlation with tissue eosinophilia, however, no clinical biomarkers for tissue zinc levels have been identified. Metallothionein-3 (MT3) is an intracellular zinc chelator and previous data showed MT3 mRNA levels to be reduced in CRS patients with nasal polyps (CRSwNP). In this study, we examined the correlation between MT3 expression and zinc levels in nasal mucosa and primary human nasal epithelial cells (HNECs) to investigate whether MT3 could be a clinical biomarker for tissue zinc levels.

METHOD

Tissue was harvested from 36 patients and mounted on tissue micro-array (TMA) slides. MT3 expression and tissue zinc fluorescence intensity were measured at different areas within the mucosa (surface epithelium and lamina propria) and compared between controls, CRSwNP and CRS without nasal polyps (CRSsNP) patients. MT3 mRNA and protein expression were examined in zinc-depleted HNECs by qPCR and immunofluorescence microscopy.

RESULTS

MT3 expression in CRSwNP was significantly decreased in both surface epithelium (p<0.001 to controls) and lamina propria (p = 0.0491 to controls). There was a significant positive correlation between tissue zinc levels and MT3 expression in nasal mucosa (r = 0.45, p = 0.007). In zinc-deplete HNECs, MT3 expression was significantly decreased at mRNA (p = 0.02) and protein level (p<0.01). There was a significant positive correlation between tissue zinc levels and MT3 expression within individual HNECs (r = 0.59, p<0.001).

CONCLUSIONS

MT3 expression reflects intramucosal zinc levels in both nasal mucosa and HNECs indicating MT3 could be used as a clinical biomarker for monitoring intracellular zinc levels in the nasal mucosa.

The role of labile Zn2+ and Zn2+-transporters in the pathophysiology of mitochondria dysfunction in cardiomyocytes

An important energy supplier of cardiomyocytes is mitochondria, similar to other mammalian cells. Studies have demonstrated that any defect in the normal processes controlled by mitochondria can lead to abnormal ROS production, thereby high oxidative stress as well as lack of ATP. Taken into consideration, the relationship between mitochondrial dysfunction and overproduction of ROS as well as the relation between increased ROS and high-level release of intracellular labile Zn²⁺, those bring into consideration the importance of the events related with those stimuli in cardiomyocytes responsible from cellular Zn²⁺-homeostasis and responsible Zn²⁺-transporters associated with the Zn²⁺-homeostasis and Zn²⁺-signaling. Zn²⁺-signaling, controlled by cellular Zn²⁺-homeostatic mechanisms, is regulated with intracellular labile Zn²⁺ levels, which are controlled, especially, with the two Zn²⁺-transporter families; ZIPs and ZnTs. Our experimental studies in mammalian cardiomyocytes and human heart tissue showed that Zn²⁺-transporters localizes to mitochondria besides sarco(endo)plasmic reticulum and Golgi under physiological condition. The protein levels as well as functions of those transporters can re-distribute under pathological conditions, therefore, they can interplay among organelles in cardiomyocytes to adjust a proper intracellular labile Zn²⁺ level. In the present review, we aimed to summarize the already known Zn²⁺-transporters localize to mitochondria and function to stabilize not only the cellular Zn²⁺ level but also cellular oxidative stress status. In conclusion, one can propose that a detailed understanding of cellular Zn²⁺-homeostasis and Zn²⁺-signaling through mitochondria may emphasize the importance of new mitochondria-targeting agents for prevention and/or therapy of cardiovascular dysfunction in humans.

Increase in Epithelial Permeability and Cell Metabolism by High Mobility Group Box 1, Inflammatory Cytokines and TPEN in Caco-2 Cells as a Novel Model of Inflammatory Bowel Disease

High mobility group box 1 protein (HMGB1) is involved in the pathogenesis of inflammatory bowel disease (IBD). Patients with IBD develop zinc deficiency. However, the detailed roles of HMGB1 and zinc deficiency in the intestinal epithelial barrier and cellular metabolism of IBD remain unknown. In the present study, Caco-2 cells in 2D culture and 2.5D Matrigel culture were pretreated with transforming growth factor-β (TGF-β) type 1 receptor kinase inhibitor EW-7197, epidermal growth factor receptor (EGFR) kinase inhibitor AG-1478 and a TNFα antibody before treatment with HMGB1 and inflammatory cytokines (TNFα and IFNγ). EW-7197, AG-1478 and the TNFα antibody prevented hyperpermeability induced by HMGB1 and inflammatory cytokines in 2.5D culture. HMGB1 affected cilia formation in 2.5D culture. EW-7197, AG-1478 and the TNFα antibody prevented the increase in cell metabolism induced by HMGB1 and inflammatory cytokines in 2D culture. Furthermore, ZnSO₄ prevented the hyperpermeability induced by zinc chelator TPEN in 2.5D culture. ZnSO₄ and TPEN induced cellular metabolism in 2D culture. The disruption of the epithelial barrier induced by HMGB1 and inflammatory cytokines contributed to TGF-β/EGF signaling in Caco-2 cells. The TNFα antibody and ZnSO₄ as well as EW-7197 and AG-1478 may have potential for use in therapy for IBD.

Evaluating effects of zinc hydroxychloride on biomarkers of inflammation and intestinal integrity during feed restriction

Objectives were to evaluate effects of supplemental zinc hydroxychloride (HYD; Micronutrients, Indianapolis, IN) on gut permeability, metabolism, and inflammation during feed restriction (FR). Holstein cows (n = 24; 159 ± 8 d in milk; parity 3 ± 0.2) were enrolled in a 2 × 2 factorial design and randomly assigned to 1 of 4 treatments: (1) ad libitum fed (AL) and control diet (ALCON; 75 mg/kg Zn from zinc sulfate; n = 6); (2) ad libitum fed and HYD diet (ALHYD; 75 mg/kg Zn from HYD; n = 6); (3) 40% of ad libitum feed intake and control diet (FRCON; n = 6); or (4) 40% of ad libitum feed intake and HYD diet (FRHYD; n = 6). Prior to study initiation, cows were fed their respective diets for 21 d. The trial consisted of 2 experimental periods (P) during which cows continued to receive their respective dietary treatments. Period 1 (5 d) served as the baseline for P2 (5 d), during which cows were fed ad libitum or restricted to 40% of P1 feed intake. In vivo total-tract permeability was evaluated on d 4 of P1 and on d 2 and 5 of P2, using the paracellular permeability marker chromium (Cr)-EDTA. All cows were euthanized at the end of P2 to assess intestinal architecture. As anticipated, FR cows lost body weight (∼46 kg), entered into calculated negative energy balance (-13.86 Mcal/d), and had decreased milk yield. Circulating glucose, insulin, and glucagon decreased, and nonesterified fatty acids and β-hydroxybutyrate increased in FR relative to AL cows. Relative to AL cows, FR increased lipopolysaccharide-binding protein, serum amyloid A (SAA), and haptoglobin (Hp) concentrations (2-, 4-, and 17-fold, respectively); and peak SAA and Hp concentrations were observed on d 5. Circulating SAA and Hp from FRHYD tended to be decreased (47 and 61%, respectively) on d 5 relative to FRCON. Plasma Cr area under the curve increased (32%) in FR treatments on d 2 and tended to be increased (17%) on d 5 of P2 relative to AL treatments. No effects of diet were observed on Cr appearance. Relative to AL cows, FR increased jejunum villus width and decreased jejunum crypt depth and ileum villus height and crypt depth. Relative to FRCON, ileum villus height tended to increase in FRHYD cows. Feed restriction tended to decrease jejunum and ileum mucosal surface area, but the decrease in the ileum was ameliorated by dietary HYD. In summary, FR induced gut hyperpermeability to Cr-EDTA, and feeding HYD appeared to benefit some key metrics of barrier integrity.

The Znt7-null mutation has sex dependent effects on the gut microbiota and goblet cell population in the mouse colon

Cellular homeostasis of zinc, an essential element for living organisms, is tightly regulated by a family of zinc transporters. The zinc transporter 7, ZnT7, is highly expressed on the membrane of the Golgi complex of intestinal epithelial cells and goblet cells. It has previously been shown that Znt7 knockout leads to zinc deficiency and decreased weight gain in C57BL/6 mice on a defined diet. However, effects within the colon are unknown. Given the expression profile of Znt7, we set out to analyze the changes in mucin density and gut microbial composition in the mouse large intestine induced by Znt7 knockout. We fed a semi-purified diet containing 30 mg Zn/kg to Znt7^-/- mice with their heterozygous and wild type littermates and found a sex specific effect on colonic mucin density, goblet cell number, and microbiome composition. In male mice Znt7 knockout led to increased goblet cell number and mucin density but had little effect on gut microbiome composition. However, in female mice Znt7 knockout was associated with decreased goblet cell number and mucin density, with increased proportions of the microbial taxa, Allobaculum, relative to wild type. The gut microbial composition was correlated with mucin density in both sexes. These findings suggest that a sex-specific relationship exists between zinc homeostasis, mucin production and the microbial community composition within the colon.

Emerging medical therapies for severe alcoholic hepatitis

Severe alcoholic hepatitis (AH) is an acute and often devastating form of alcohol-associated liver disease. Clinically, AH is characterized by elevated bilirubin, model for end stage liver disease scores >20, and nonspecific symptoms that are caused by underlying inflammation, hepatocyte injury, and impaired intestinal barrier function. Compromised immune defense in AH contributes to infections, sepsis and organ failure. To date, corticosteroids are the only recommended treatment for severe AH, however it does not provide survival benefits beyond 1 month. Recent preclinical and early clinical studies in AH aided understanding of the disease and presented opportunities for new therapeutic options targeting inflammation, oxidative stress, liver regeneration and modification of intestinal microbiota. In this comprehensive review, we discuss promising preclinical results and ongoing clinical trials evaluating novel therapeutic agents for the treatment of severe AH.

Zinc Deficiency Induces Oxidative Damage and Causes Spleen Fibrosis

Zinc (Zn) is an essential trace element for animals. Zn controls the action of more than 300 enzymes and plays an important role in the regulation of gene expression. Evidence has shown that Zn has an antioxidant function, and oxidative damage can occur with Zn deficiency. To assess the effect of Zn deficiency-induced spleen fibrosis, Zn-deficient mice, normal mice, and high-Zn mice were generated and assessed. The Zn content of the spleen in each group was determined, and histopathological examination of the spleens of each group was performed. In the film, we found that the spleens of the Zn-deficient group had high levels of proteinaceous material exudation, interstitial broadening, and lymphocyte reduction, with increased collagen, α-SMA expression, antioxidants, and oxygen free radicals. Zn deficiency inhibited the expression of antioxidants in mice, and the activity of oxygen free radicals in Zn-deficient mice was increased. The detection of α-SMA, collagen 1, and TGF-β by fluorescence quantitative PCR revealed that the expression index increased in Zn-deficient mice. In addition, to verify the effect of Zn deficiency on the extracellular matrix (ECM) regulatory system, MMPs were determined by real-time PCR, and the expression in the Zn deficiency group was lower than that in the normal group and high-Zn group. The MMP-2 and MMP-13 analyses showed that the expression of the high-Zn group was significantly higher than that of the normal group, indicating that Zn plays an important role in its expression. The above experimental analysis showed that Zn deficiency induces oxygen free radical damage, which further leads to spleen fibrosis.

Role of Dietary Nutrients in the Modulation of Gut Microbiota: A Narrative Review

Understanding how dietary nutrients modulate the gut microbiome is of great interest for the development of food products and eating patterns for combatting the global burden of non-communicable diseases. In this narrative review we assess scientific studies published from 2005 to 2019 that evaluated the effect of micro- and macro-nutrients on the composition of the gut microbiome using in vitro and in vivo models, and human clinical trials. The clinical evidence for micronutrients is less clear and generally lacking. However, preclinical evidence suggests that red wine- and tea-derived polyphenols and vitamin D can modulate potentially beneficial bacteria. Current research shows consistent clinical evidence that dietary fibers, including arabinoxylans, galacto-oligosaccharides, inulin, and oligofructose, promote a range of beneficial bacteria and suppress potentially detrimental species. The preclinical evidence suggests that both the quantity and type of fat modulate both beneficial and potentially detrimental microbes, as well as the Firmicutes/Bacteroides ratio in the gut. Clinical and preclinical studies suggest that the type and amount of proteins in the diet has substantial and differential effects on the gut microbiota. Further clinical investigation of the effect of micronutrients and macronutrients on the microbiome and metabolome is warranted, along with understanding how this influences host health.