Nutritional aspects of manganese homeostasis

Long-term relatively high dietary manganese intake could decrease the risk of hyperuricemia: Twelve-year distinct dietary manganese consumption trajectories and the China Health and Nutrition Survey

BACKGROUND AND AIM

Currently, the relationship between dynamic changes in dietary manganese (Mn) intake and risk of hyperuricemia (HU) is still unclear. This study aimed to identify dietary Mn consumption trajectories in the Chinese adults and assess their relation with the risk of HU.

METHODS AND RESULTS

Cohort data from the China Health and Nutrition Survey (CHNS) 1997-2009 were employed in this study. Overall, 6886 adult participants were included. Participants were designated into subgroups based on the trajectories of dietary Mn consumption by sex. Cox proportional hazard models were used to explore the associations between different trajectories and the risk of HU. For men, compared with low stable trajectory group, moderate to high trajectory group was significantly related to reduced risk of HU (HR = 0.61, 95% CI: 0.38 to 0.98) with adjustment for covariates. TC, HDL-C, ApoB, and TG exerted partial regulation function between trajectories and HU. For women, compared with low stable trajectory group, high stable trajectory group was significantly related to reduced risk of HU (HR = 0.76, 95% CI: 0.60 to 0.95) with adjustment for covariates. Similarly, TC, HDL-C, ApoB, and ApoA exerted partial regulation function between trajectories and HU.

CONCLUSIONS

Long-term relatively high dietary Mn consumption may have a protective effect against HU in Chinese adults. The differences in HU-related factors among different dietary Mn intake trajectories partially regulated the association between these trajectories and HU.

Manganese matere bonds in biological systems: PDB inspection and DFT calculations

A Protein Data Bank (PDB) survey has revealed noncovalent contacts involving Mn centres and protein residues. Their geometrical features are in line with the interaction between low electron density sites located along the Mn-O/N coordination bonds (σ-holes) and the lone pairs belonging to TYR, SER or HIS residues, known as a matere bond (MaB). Calculations at the PBE0-D3/def2-TZVP level of theory were used to investigate the strength and shed light on the physical nature of the interaction. We expect the results presented herein will be useful for those scientists working in the fields of bioinorganic chemistry, particulary in protein-metal docking, by providing new insights into transition metal⋯Lewis base interactions as well as a retrospective point of view to further understand the structural and functional implications of this key transition metal ion.

A prospective cohort study of multimetal exposure and risk of gestational diabetes mellitus

The relationship between co-exposure to multiple metals and gestational diabetes mellitus (GDM) and the mechanisms involved are poorly understood. In this nested case-control study, 228 GDM cases and 456 matched controls were recruited, and biological samples were collected at 12-14 gestational weeks. The urinary concentrations of 10 metals and 8-hydroxydeoxyguanosine (8-OHdG) as well as the serum levels of malondialdehyde (MDA) and advanced glycation end products (AGEs) were determined to assess the association of metals with GDM risk and the mediating effects of oxidative stress. Urinary Ti concentration was significantly and positively associated with the risk of GDM (odds ratio [OR]:1.45, 95 % confidence interval [CI]: 1.12, 1.88), while Mn and Fe were negatively associated with GDM risk (OR: 0.67, 95 % CI: 0.50, 0.91 or OR: 0.61, 95 % CI: 0.47, 0.80, respectively). A significant negative association was observed between Mo and GDM risk, specifically in overweight and obese pregnant women. Bayesian kernel machine regression showed a significant negative joint effect of the mixture of 10 metals on GDM risk. The adjusted restricted cubic spline showed a protective role of Mn and Fe in GDM risk (P < 0.05). A significant negative association was observed between essential metals and GDM risk in quantile g-computation analysis (P < 0.05). Mediation analyses showed a mediating effect of MDA on the association between Ti and GDM risk, with a proportion of 8.7 % (P < 0.05), and significant direct and total effects on Ti, Mn, and Fe. This study identified Ti as a potential risk factor and Mn, Fe, and Mo as potential protective factors against GDM, as well as the mediating effect of lipid oxidation.

Heavy Metal Interactions with Neuroglia and Gut Microbiota: Implications for Huntington's Disease

Huntington's disease (HD) is a rare but progressive and devastating neurodegenerative disease characterized by involuntary movements, cognitive decline, executive dysfunction, and neuropsychiatric conditions such as anxiety and depression. It follows an autosomal dominant inheritance pattern. Thus, a child who has a parent with the mutated huntingtin (mHTT) gene has a 50% chance of developing the disease. Since the HTT protein is involved in many critical cellular processes, including neurogenesis, brain development, energy metabolism, transcriptional regulation, synaptic activity, vesicle trafficking, cell signaling, and autophagy, its aberrant aggregates lead to the disruption of numerous cellular pathways and neurodegeneration. Essential heavy metals are vital at low concentrations; however, at higher concentrations, they can exacerbate HD by disrupting glial-neuronal communication and/or causing dysbiosis (disturbance in the gut microbiota, GM), both of which can lead to neuroinflammation and further neurodegeneration. Here, we discuss in detail the interactions of iron, manganese, and copper with glial-neuron communication and GM and indicate how this knowledge may pave the way for the development of a new generation of disease-modifying therapies in HD.

The toxicological analysis and assessment of essential elements (Cu, Fe, Mn, Zn) in Food for Special Medical Purposes (FSMP) dedicated to oncological patients available in Polish pharmacies

Foods for Special Medical Purposes (FSMP) for oncology patients, available in pharmacies, play a crucial role in providing nutrition and supplementation. However, the scientific literature lacks comprehensive research on the safety of essential trace elements in these products. This study aimed to assess Cu, Fe, Mn and Zn levels in commonly prescribed FSMPs (n = 23) from Polish pharmacies. Using ICP-MS after microwave-induced digestion (using concentrated nitric acid and hydrogen peroxide), we evaluated element levels. Our research used three approaches: the raw score for Cu, Fe, Mn, and Zn; single intake per serving; and the daily ration, compared with the reference values of the European Food Safety Authority. Discrepancies were found between the actual and declared product compositions, influenced by the route of administration and the recommended intake. Despite variations, all products were considered safe for oncological patients based on current evidence. However, it is recommended to have clear guidelines for FSMPs in cancer care. This pioneering study evaluates the safety and quality of prescription FSMPs for cancer patients from toxicological and nutritional perspectives, highlighting the need for standardised protocols in pharmacy-dispensed FSMPs.

Regulation of anti-tumor immunity by metal ion in the tumor microenvironment

Metal ions play an essential role in regulating the functions of immune cells by transmitting intracellular and extracellular signals in tumor microenvironment (TME). Among these immune cells, we focused on the impact of metal ions on T cells because they can recognize and kill cancer cells and play an important role in immune-based cancer treatment. Metal ions are often used in nanomedicines for tumor immunotherapy. In this review, we discuss seven metal ions related to anti-tumor immunity, elucidate their roles in immunotherapy, and provide novel insights into tumor immunotherapy and clinical applications.

Vitamins, minerals and their maternal levels' role in brain development: An updated literature-review

One's neurobehavioural and mental health are built during the exact and complex process of brain development. It is thought that fetal development is where neuropsychiatric disorders first emerged. Behavioural patterns can change as a result of neuropsychiatric illnesses. The incidence is rising quickly; nevertheless, providing exceptional care remains a significant challenge for families and healthcare systems. It has been demonstrated that one of the main factors causing the transmission of these diseases is maternal exposure. Through physiologic pathways, maternal health and intrauterine exposures can affect brain development. Our attention has been focused on epigenetic factors, particularly in the gestational environment, which may be responsible for human neurodegenerative diseases since our main mental development occurs during the nine months of intrauterine life. After thoroughly searching numerous databases, this study examined the effect of fat-soluble vitamins, water-soluble vitamins, and minerals and their maternal-level effect on brain development.

The manganese transporter SLC39A8 links alkaline ceramidase 1 to inflammatory bowel disease

The metal ion transporter SLC39A8 is associated with physiological traits and diseases, including blood manganese (Mn) levels and inflammatory bowel diseases (IBD). The mechanisms by which SLC39A8 controls Mn homeostasis and epithelial integrity remain elusive. Here, we generate Slc39a8 intestinal epithelial cell-specific-knockout (Slc39a8-IEC KO) mice, which display markedly decreased Mn levels in blood and most organs. Radiotracer studies reveal impaired intestinal absorption of dietary Mn in Slc39a8-IEC KO mice. SLC39A8 is localized to the apical membrane and mediates 54Mn uptake in intestinal organoid monolayer cultures. Unbiased transcriptomic analysis identifies alkaline ceramidase 1 (ACER1), a key enzyme in sphingolipid metabolism, as a potential therapeutic target for SLC39A8-associated IBDs. Importantly, treatment with an ACER1 inhibitor attenuates colitis in Slc39a8-IEC KO mice by remedying barrier dysfunction. Our results highlight the essential roles of SLC39A8 in intestinal Mn absorption and epithelial integrity and offer a therapeutic target for IBD associated with impaired Mn homeostasis.

Association and Pathways between Dietary Manganese Intake and Incident Venous Thromboembolism

BACKGROUND

 The association between dietary manganese (Mn) intake and the risk of venous thromboembolism (VTE) remains unknown. We aimed to investigate the associations of dietary Mn intake with incident VTE, and the underlying mediating roles of obesity markers (body mass index [BMI] and waist circumference), hemorheological parameters (red cell distribution width [RDW], platelet count [PLT], and mean platelet volume [MPV]), and inflammatory biomarkers (C-reactive protein [CRP] and white blood cell count [WBC]) in this association.

METHODS

 A total of 202,507 adults from the UK Biobank with complete dietary data and without VTE at baseline were included. Dietary information was collected by the online 24-hour diet recall questionnaires (Oxford WebQ). The primary outcome was incident VTE, a composite of incident deep vein thrombosis (DVT) and pulmonary embolism (PE).

RESULTS

 During a median follow-up of 11.6 years, 4,750 participants developed incident VTE. Overall, there were significantly inverse relationships of dietary Mn intake with incident VTE (per 1 mg/day increment; adjusted hazard ratio [HR]: 0.92; 95% confidence interval [CI]: 0.90-0.95), incident DVT (per 1 mg/day increment; adjusted HR: 0.93; 95% CI: 0. 90-0.96), and incident PE (per 1 mg/day increment; adjusted HR: 0.91; 95% CI: 0.88-0.95). BMI, waist circumference, RDW, CRP, and WBC significantly mediated the association between dietary Mn intake and incident VTE, with the mediated proportions of 36.0, 36.5, 4.2, 4.3, and 1.6%, respectively. However, MPV and PLT did not significantly mediate the association.

CONCLUSION

 Our study shows that dietary Mn intake was inversely associated with incident VTE. The inverse association was mainly mediated by obesity, followed by inflammatory biomarkers and RDW. Our findings are just hypothesis-generating, and further confirmation of our findings in more studies is essential.

Specific of accumulation of manganese in organs and tissues of Hereford cattle

The elemental status of cattle is one of the important factors, which determine its growth, fertility, fetal development, meat and dairy production, etc. Therefore, the study of content of different elements in cattle organs and tissues and its correlation with cattle characteristics and diet is urgent task. It is also important to develop intravital and low-invasive methods to analyze element content in cattle to regulate its diet during lifetime. In the present work, we have studied the content and distribution of manganese in Hereford cattle from an ecologically clean zone of Western Siberia (Russia). 252 samples were taken from 31 bulls aged 15-18 months. They were collected from various livestock farms in the region and analyzed using atomic absorption spectrophotometry (organs and muscle tissue) and inductively coupled plasma atomic emission spectrometry (hair). The median values of manganese concentration obtained in natural moisture for hair, heart, kidneys, liver, lungs, muscles, spleen, testes, and brain were 25, 0.37, 1.0, 2.6, 0.4, 0.2, 0.4, 0.5, and 0.5 ppm. Accordingly, the concentration of manganese differs significantly in the organs and tissues of animals (H = 188.6, df = 8, p <0.0001). Statistically significant associations of manganese were revealed in pairs: liver-testis, hair-testis, spleen-testis, and heart-brain. The classification of organs and tissues of animals according to the level of content and variability of manganese is carried out. The concentration of manganese in the body is not uniform, most of all it is deposited in the hair and excretory organs of the liver and kidneys. In other organs and muscle tissues, the distribution of manganese is more even and is in the range of 0.2-0.5 ppm. The resulting ranges can be used as a guideline for Hereford cattle bred in Western Siberia.

Acute manganese toxicosis related to joint health supplement ingestion in two dogs

Two unrelated dogs residing in the same house including an 11-year-old, female spayed, mixed breed dog and a 7-year-old, female spayed, mixed breed dog ingested approximately 75 capsules of a human joint health supplement (Ligaplex I; Standard Process, WI, USA). A total of 2,062 mg of manganese was ingested between both dogs. Dog 1 developed acute fulminant liver failure and a severe coagulopathy that led to hepatic fractures and exsanguination from hemoabdomen. The estimated maximum time from ingestion of the joint health supplement to death was 36 to 48 h. Histologic examination revealed severe periportal hepatic necrosis with mild evidence of preexisiting liver disease and renal tubular epithelial necrosis. Manganese concentrations in liver and kidney tissue were severely increased. Dog 2 developed a severe acute liver injury and was hospitalized for 6 days. Therapies provided during hospitalization included intravenous fluids, maropitant, pantoprazole, N-acetylcysteine, vitamin C, S-adenosylmethionine, and silybin. The dog was treated long-term with S-adenosylmethionine, silybin, ursodiol, and vitamin C. Clinical and biochemical resolution occurred on the recheck examination that took place on day 44. The veterinary literature is comprised of only 2 reports containing 3 dogs that describe acute manganese intoxication. Here, we provide a detailed description of 2 dogs that developed manganese-induced toxicosis after ingestion of a human joint health supplement.

Associations between seminal plasma metals/metalloids and semen quality: A cross-sectional study

Exposure to metals/metalloids is reported to potentially influence semen quality. While most studies have focused on single metal impacts, the link between exposure to multiple metals and semen quality has remained less explored. The study aimed to investigate the effects of both individual and mixed metal/metalloid exposure on semen quality. A total of 330 men were recruited from three reproductive centers in eastern China. Seminal plasma levels of 25 metals/metalloids and sperm parameters were determined. We used the Generalized Linear Model (GLM) and Restricted Cubic Spline (RCS) to assess the relationships between single metals/metalloids and semen quality. The weighted quantile sum (WQS) models were then applied to evaluate the combined effect of all these metals/metalloids. We observed positive associations of exposure to lithium (Li), zinc (Zn), and magnesium (Mg) with an increased risk of below reference values for progressive motility and total motility using a logistic regression model (P < 0.05). Additionally, our results also revealed a significant inverse relationship between aluminum (Al) and both sperm concentration and count, while cobalt (Co) demonstrated a positive association with sperm concentration (P < 0.05). Notably, the WQS model indicated a significant positive association between exposure to metal/metalloid mixtures and the risk of abnormal progressive motility (OR: 1.57; 95%CI: 1.10, 2.24) and abnormal total motility (OR: 1.53; 95%CI: 1.06, 2.19), with this association primarily driven by Li, Mg, and Zn. In summary, our findings indicate that exposure to metal/metalloid mixtures might have an adverse effect on semen quality.

Associations between blood manganese levels and sarcopenia in adults: insights from the National Health and Nutrition Examination Survey

Background

While increasing concerns arise about the health effects of environmental pollutants, the relationship between blood manganese (Mn) and sarcopenia has yet to be fully explored in the general population.

Objective

This study aims to investigate the association between blood manganese (Mn) levels and sarcopenia in adults.

Methods

In our study, we evaluated 8,135 individuals aged 18-59 years, utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2011 to 2018. We employed generalized additive model (GAM) to discern potential non-linear relationships and utilized the two-piecewise linear regression model to probe the association between blood Mn levels and sarcopenia.

Results

After adjusting for potential confounders, we identified non-linear association between blood Mn levels and sarcopenia, with an inflection point at 13.45 μg/L. The effect sizes and the confidence intervals on the left and right sides of the inflection point were 1.006 (0.996 to 1.048) and 1.082 (1.043 to 1.122), respectively. Subgroup analysis showed that the effect sizes of blood Mn on sarcopenia have significant differences in gender and different BMI groups.

Conclusion

Our results showed that a reverse U-shaped curve between blood Mn levels and sarcopenia, with an identified the inflection point at blood Mn level of 13.45 μg/L.

The protective role of sesame oil against Parkinson's-like disease induced by manganese in rats

Chronic exposure to manganese (Mn) results in motor dysfunction, biochemical and pathological alterations in the brain. Oxidative stress, inflammation, and dysfunction of dopaminergic and GABAergic systems stimulate activating transcription factor-6 (ATF-6) and protein kinase RNA-like ER kinase (PERK) leading to apoptosis. This study aimed to investigate the protective effect of sesame oil (SO) against Mn-induced neurotoxicity. Rats received 25 mg/kg MnCl2 and were concomitantly treated with 2.5, 5, or 8 ml/kg of SO for 5 weeks. Mn-induced motor dysfunction was indicated by significant decreases in the time taken by rats to fall during the rotarod test and in the number of movements observed during the open field test. Also, Mn resulted in neuronal degeneration as observed by histological staining. The striatal levels of lipid peroxides and reduced glutathione (oxidative stress markers), interleukin-6 and tumor necrosis factor-α (inflammatory markers) were significantly elevated. Mn significantly reduced the levels of dopamine and Bcl-2, while GABA, PERK, ATF-6, Bax, and caspase-3 were increased. Interestingly, all SO doses, especially at 8 ml/kg, significantly improved locomotor activity, biochemical deviations and reduced neuronal degeneration. In conclusion, SO may provide potential therapeutic benefits in enhancing motor performance and promoting neuronal survival in individuals highly exposed to Mn.

Is there a fast track ("Darmstrasse") for fluids in the small intestine? Evidence from magnetic resonance imaging

BACKGROUND

The transit and distribution pattern of fluids in the small intestine is a key parameter for the dissolution and absorption of drugs. Although some information is known about the small intestinal water content after administration of fluid volumes and meals, the intestinal transit of orally ingested fluids and solutions has been barely investigated. The aim of this three-arm, cross-over, 9-subject human study was to investigate the transit of orally ingested water in the small intestine under fasting and postprandial conditions using MRI. To identify the ingested water, manganese gluconate, which can be identified with T1-weighted MRI sequences, was added as a marker. Using Horos (DICOM software), quantification of the distribution of Mn2+ ions in the gastrointestinal tract in fasted versus fed state (standard meal by FDA guidance and a light meal) was possible. The distribution and approximate wetted intestinal length was very similar in the fasting and postprandial states, suggesting rapid transport of water ingested after a meal through the chyme-filled small intestine in continuation of the "Magenstrasse" (stomach road). In some subjects, manganese gluconate reached deeper parts of the small intestine even more quickly in the postprandial state than in the fasting arm of the study. A deeper understanding of the behaviour of solutes in the gastrointestinal tract is fundamental to a mechanistic explanation for the kinetic interaction between food and drug intake (food effects).

Association between serum trace element, mineral, and amino acid levels with non-alcoholic fatty liver disease (NAFLD) in adult women

The objective of the present study is assessment of serum trace element and amino acid levels in non-alcoholic fatty liver disease (NAFLD) patients with subsequent evaluation of its independent associations with markers of liver injury and metabolic risk.

MATERIALS AND METHODS

140 women aged 20-90 years old with diagnosed NAFLD and 140 healthy women with a respective age range were enrolled in the current study. Analysis of serum and hair levels of trace elements and minerals was performed with inductively-coupled plasma mass-spectrometry (ICP-MS). Serum amino acid concentrations were evaluated by high-pressure liquid chromatography (HPLC) with UV-detection. In addition, routine biochemical parameters including liver damage markers, alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT), were assessed spectrophotometrically.

RESULTS

The findings demonstrated that patients with NAFLD were characterized by higher ALT, GGT, lactate dehydrogenase (LDH) and cholinesterase (CE) activity, as well as increased levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and uric acid. NAFLD patients were characterized by reduced serum and hair Co, Se, and Zn levels, as well as hair Cu content and serum Mn concentrations in comparison to controls. Circulating Ala, Cit, Glu, Gly, Ile, Leu, Phe, and Tyr levels in NAFLD patients exceeded those in the control group. Multiple linear regression demonstrated that serum and hair trace element levels were significantly associated with circulating amino acid levels after adjustment for age, BMI, and metabolic parameters including liver damage markers.

CONCLUSION

It is proposed that altered trace element handling may contribute to NAFLD pathogenesis through modulation of amino acid metabolism.

Manganese Overexposure Alters Neurogranin Expression and Causes Behavioral Deficits in Larval Zebrafish

Manganese (Mn), a cofactor for various enzyme classes, is an essential trace metal for all organisms. However, overexposure to Mn causes neurotoxicity. Here, we evaluated the effects of exposure to Mn chloride (MnCl2) on viability, morphology, synapse function (based on neurogranin expression) and behavior of zebrafish larvae. MnCl2 exposure from 2.5 h post fertilization led to reduced survival (60%) at 5 days post fertilization. Phenotypical changes affected body length, eye and olfactory organ size, and visual background adaptation. This was accompanied by a decrease in both the fluorescence intensity of neurogranin immunostaining and expression levels of the neurogranin-encoding genes nrgna and nrgnb, suggesting the presence of synaptic alterations. Furthermore, overexposure to MnCl2 resulted in larvae exhibiting postural defects, reduction in motor activity and impaired preference for light environments. Following the removal of MnCl2 from the fish water, zebrafish larvae recovered their pigmentation pattern and normalized their locomotor behavior, indicating that some aspects of Mn neurotoxicity are reversible. In summary, our results demonstrate that Mn overexposure leads to pronounced morphological alterations, changes in neurogranin expression and behavioral impairments in zebrafish larvae.

The relationship between serum manganese concentration with all-cause and cause-specific mortality: a retrospective and population-based cross-sectional study

BACKGROUND

The study aimed to explore the association between manganese concentration and all-cause, cardiovascular disease (CVD)-related, and cancer-related mortality in the general population of the United States.

METHODS

We integrated the data from the National Health and Nutrition Examination Survey from 2011 to 2018. A total of 9,207 subjects were selected based on the inclusion and exclusion criteria. The relationship between manganese concentration and all-cause, CVD-related, and cancer-related mortality was analyzed by constructing a Cox proportional hazard regression model and a restricted cubic spline (RCS) plot. Additionally, subgroup analyses stratified by age, sex, race/ethnicity, hypertension, diabetes mellitus (DM), chronic heart disease, chronic heart failure, angina pectoris, heart attack, stroke, and BMI were further performed.

RESULTS

In the full adjusted model, compared with the lowest quartile, the adjusted hazard ratios with 95% confidence intervals (CIs) for all-cause, CVD-related, and cancer-related mortality across manganese quartiles were (1.11 (0.87,1.41), 0.96 (0.74, 1.23), and 1.23 (0.96, 1.59); P-value for trend =0.041), (0.86 (0.54, 1.37), 0.87 (0.55, 1.40), and 1.07 (0.67, 1.72); P-value for trend =0.906), and (1.45 (0.92, 2.29), 1.14 (0.70, 1.88), and 1.26 (0.75, 2.11); P-value for trend =0.526), respectively. The RCS curve shown a U-shaped association between manganese concentration and all-cause mortality and CVD-related mortality (P-value for nonlinear <0.05). However, there was an increase and then a decrease in the link between manganese concentration and cancer-related mortality (P-value for nonlinear <0.05). Manganese exposure was positively correlated with sex (correlation coefficient, r =0.19, P-value <0.001) and negatively correlated with age (correlation coefficient, r =-0.11, P-value <0.001) and serum creatinine (correlation coefficient, r =-0.12, P-value <0.001), respectively.

CONCLUSIONS

Our findings suggest that elevated serum manganese concentrations are associated with all-cause and CVD-related mortality in the U.S. population and that maintenance of serum manganese between 8.67-9.23 µg/L may promote public health.

Probabilistic risk assessment of residential exposure to electric arc furnace steel slag using Bayesian model of relative bioavailability and PBPK modeling of manganese

Electric arc furnace (EAF) slag is a coproduct of steel production used primarily for construction purposes. Some applications of EAF slag result in residential exposures by incidental ingestion and inhalation of airborne dust. To evaluate potential health risks, an EAF slag characterization program was conducted to measure concentrations of metals and leaching potential (including oral bioaccessibility) in 38 EAF slag samples. Arsenic, hexavalent chromium, iron, vanadium, and manganese (Mn) were identified as constituents of interest (COIs). Using a probabilistic risk assessment (PRA) approach, estimated distributions of dose for COIs were assessed, and increased cancer risks and noncancer hazard quotients (HQs) at the 50th and 95th percentiles were calculated. For the residents near slag-covered roads, cancer risk and noncancer HQs were <1E - 6 and 1, respectively. For residential driveway or landscape exposure, at the 95th percentile, cancer risks were 1E - 6 and 7E - 07 based on oral exposure to arsenic and hexavalent chromium, respectively. HQs ranged from 0.07 to 2 with the upper bound due to ingestion of Mn among children. To expand the analysis, a previously published physiologically based pharmacokinetic (PBPK) model was used to estimate Mn levels in the globus pallidus for both exposure scenarios and further evaluate the potential for Mn neurotoxicity. The PBPK model estimated slightly increased Mn in the globus pallidus at the 95th percentile of exposure, but concentrations did not exceed no-observed-adverse-effect levels for neurological effects. Overall, the assessment found that the application of EAF slag in residential areas is unlikely to pose a health hazard or increased cancer risk.

Zinc and manganese homeostasis closely interact in mammalian cells

Understanding the homeostatic interactions among essential trace metals is important for explaining their roles in cellular systems. Recent studies in vertebrates suggest that cellular Mn metabolism is related to Zn metabolism in multifarious cellular processes. However, the underlying mechanism remains unclear. In this study, we examined the changes in the expression of proteins involved in cellular Zn and/or Mn homeostatic control and measured the Mn as well as Zn contents and Zn enzyme activities to elucidate the effects of Mn and Zn homeostasis on each other. Mn treatment decreased the expression of the Zn homeostatic proteins metallothionein (MT) and ZNT1 and reduced Zn enzyme activities, which were attributed to the decreased Zn content. Moreover, loss of Mn efflux transport protein decreased MT and ZNT1 expression and Zn enzyme activity without changing extracellular Mn content. This reduction was not observed when supplementing with the same Cu concentrations and in cells lacking Cu efflux proteins. Furthermore, cellular Zn homeostasis was oppositely regulated in cells expressing Zn and Mn importer ZIP8, depending on whether Zn or Mn concentration was elevated in the extracellular milieu. Our results provide novel insights into the intricate interactions between Mn and Zn homeostasis in mammalian cells and facilitate our understanding of the physiopathology of Mn, which may lead to the development of treatment strategies for Mn-related diseases in the future.

Biocompatible and bioactivable terpolymer-lipid-MnO2 Nanoparticle-based MRI contrast agent for improving tumor detection and delineation

Early and precise detection of solid tumor cancers is critical for improving therapeutic outcomes. In this regard, magnetic resonance imaging (MRI) has become a useful tool for tumor diagnosis and image-guided therapy. However, its effectiveness is limited by the shortcomings of clinically available gadolinium-based contrast agents (GBCAs), i.e. poor tumor penetration and retention, and safety concerns. Thus, we have developed a novel nanoparticulate contrast agent using a biocompatible terpolymer and lipids to encapsulate manganese dioxide nanoparticles (TPL-MDNP). The TPL-MDNP accumulated in tumor tissue and produced paramagnetic Mn2+ ions, enhancing T1-weight MRI contrast via the reaction with H2O2 rich in the acidic tumor microenvironment. Compared to the clinically used GBCA, Gadovist®1.0, TPL-MDNP generated stronger T1-weighted MR signals by over 2.0-fold at 30 % less of the recommended clinical dose with well-defined tumor delineation in preclinical orthotopic tumor models of brain, breast, prostate, and pancreas. Importantly, the MRI signals were retained for 60 min by TPL-MDNP, much longer than Gadovist®1.0. Biocompatibility of TPL-MDNP was evaluated and found to be safe up to 4-fold of the dose used for MRI. A robust large-scale manufacturing process was developed with batch-to-batch consistency. A lyophilization formulation was designed to maintain the nanostructure and storage stability of the new contrast agent.

Bioaccumulation of Potentially Toxic Elements in Commercially Important Food Fish Species from Lower Gangetic Stretch: Food Security and Human Health Risk Assessment

Ganga river is the inhabitant of more than 190 fish species and important river system of India. Potentially toxic elements (PTEs) in the Gangetic riverine ecosystem are a hot environmental issue. A detailed evaluation of PTEs bioaccumulation in Gangetic fishes is required to safeguard human health. The present study investigated the bioaccumulation of PTEs (Cd, Co, Cr, Cu, Li, Ni, Pb, Se, Zn, and Mn) within 12 economic fish species (n = 72) collected from the lower Gangetic stretch. The mean concentrations of PTEs followed the order Zn > Cu > Mn > Ni > Se > Cr > Pb > Co ~ Li > Cd. Li and Se bioaccumulation were studied first time from Gangetic fishes. Results demonstrated that all the selected PTEs were below the maximum permissible limit recommended by reference standards except for Zn in L. catla and L. rohita. For all PTEs, the metal pollution index (MPI), hazard quotient (THQ), and hazard index (HI) were < 1, indicating that these PTEs do not pose a health risk to the public through the dietary intake of fish in this study area. All studied fish were acceptable in terms of carcinogenic risk (CR) from exposure to Cd, Cr, and Pb. Multivariate statistical analysis suggests that inter-correlated metals have similar dispersion properties and bioaccumulation homology within the body. This study provides a scientific basis for food safety assessment and continuous monitoring of PTEs in Gangetic fishes is suggested in the future to safeguard human health.

Positive association between dietary manganese intake and new-onset hypertension: A nationwide cohort study in China

BACKGROUND AND AIM

To date, few studies have investigated the association between dietary manganese intake and the risk of hypertension, so the prospective relationship of dietary manganese intake and new-onset hypertension remains uncertain. We aimed to investigate the association between dietary manganese intake and the risk of new-onset hypertension in the general Chinese population.

METHODS AND RESULTS

This prospective cohort study included 12,177 participants who were free of hypertension at baseline from China Health and Nutrition Survey (CHNS). Dietary intake was measured by 3 consecutive 24-h dietary recalls combined with a household food inventory. The study outcome was new-onset hypertension, defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg or diagnosed by a physician or under antihypertensive treatment during the follow-up. During a median follow-up duration of 6.1 years, 4269 (44.9 per 1000 person-years) participants developed new-onset hypertension. Overall, there was a positive association between dietary manganese intake and new-onset hypertension. The adjusted HRs (95%CIs) of new-onset hypertension were 1.00 (reference), 0.97 (0.87, 1.08), 1.24 (1.10, 1.39) and 1.75 (1.52, 2.01) across the quartiles of dietary manganese intake, respectively. Accordingly, a significantly higher risk of new-onset hypertension (HR, 1.38; 95%CI: 1.27, 1.50) was found in participants in quartiles 3-4 of dietary manganese intake (≥6.0 mg/day), compared with those in quartiles 1-2 (<6.0 mg/day).

CONCLUSIONS

In the general Chinese population, dietary manganese intake was positively associated with the risk of new hypertension, independent of sodium intake and other important covariates.

Associations of intrauterine exposure to manganese with fetal and early-childhood growth: a prospective prenatal cohort study

Prenatal manganese (Mn) exposure may be related to poor birth outcomes; however, there are few relevant epidemiological reports on the effects of intrauterine Mn levels on intrauterine fetal and early childhood growth. From 2013 to 2016, 2082 pairs of mothers and infants were recruited in Wuhan, China, who provided an entire set of urine samples during their first, second, and third trimesters. Fetal head circumference (HC), abdominal circumference (AC), femoral length (FL), and estimated fetal weight (EFW) were obtained by ultrasound at the 16, 24, and 31 weeks of pregnancy. When the children were born, 6 months old, 12 months old, and 24 months old, their weight, height, weight-for-height, and BMI were measured. We used generalized linear models, generalized estimated equations, and restricted cubic spline curves (RCS) to investigate the linear and nonlinear relationships between antenatal Mn levels and fetal and early childhood growth. In all fetuses, Mn exposure during the 1st and 2nd gestation was associated with decreased fetal AC, FL, and EFW at 24 weeks (e.g., for each doubling of urinary Mn concentrations during the 1st and 2nd gestation, the SD score of EFW at 24 weeks decreased by - 4.16% (95% CI, - 6.22%, - 2.10%) and - 3.78% (95% CI, - 5.86%, - 1.70%)). Mn concentrations in the highest tertile group of the 1st and 2nd gestation were related to decreased fetus growth parameters compared to the lowest tertile group. For each doubling of the average Mn concentrations during pregnancy, the z-scores of weight, weight-for-height, and BMI at 12 months decreased, with percentage changes of - 2.93% (95% CI, - 5.08%, - 0.79%), - 3.25% (95% CI, - 5.56%, - 0.94%), and - 3.09% (95% CI, - 5.44%, - 0.73%). In the RCS model, we found a reverse U-shaped association between 1st trimester Mn concentration and fetal FL at 16 weeks and HC at 31 weeks in male fetuses and a non-linear association between mean Mn concentration during pregnancy and girls' weight-for-height and BMI at 6 months. Intrauterine exposure to Mn may be related to restricted growth in the fetus and early childhood, especially in fetuses at 24 weeks of gestation and children at 12 months of age. Also, meaningful curvilinear relationships were found in the sex stratification.

Manganese - a scoping review for Nordic Nutrition Recommendations 2023

Manganese is an essential trace element that is required for multiple enzymes in the human body. The general population is mainly exposed to manganese via food intake, in particular plant foods. In areas with elevated concentrations of manganese in groundwater, drinking water can also be an important source of exposure. The gastrointestinal absorption of manganese is below 10%, and it appears to be influenced by the amount of manganese in the diet and by the nutritional status of the individual, especially the iron status. In blood, most of the manganese is found in the cellular fractions. Manganese is primarily eliminated via the bile followed by excretion via faeces. To date, no specific biomarkers of manganese intake have been identified. The dietary intake of manganese in the Nordic countries has been reported to be within the range that has been reported for other European countries (2-6 mg/day). Since manganese is found in nutritionally adequate amounts in food, deficiency is not of public health concern. On the other hand, there is emerging epidemiological evidence that various suggested manganese biomarkers may be negatively associated with children's neurodevelopment. However, the limited number of prospective studies, the lack of appropriate exposure biomarkers, and validated neurodevelopmental outcomes render data uncertain and inconclusive. In 2013, the European Food Safety Authority considered the evidence to be insufficient to derive an average requirement or a population reference intake, and instead an adequate intake for adults was set at 3.0 mg/day.

Manganese and Sleep Outcomes in United States Adults: Results from the 2017-2020 National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Manganese (Mn) is an essential micronutrient, but inadequate or excess Mn intake can have a detrimental impact on human health. Despite the essentiality, little is known about the relationship between Mn and sleep.

OBJECTIVE

This study aimed to examine the relationship between blood Mn concentrations and sleep outcomes in US adults.

METHODS

This cross-sectional study used data on blood Mn and sleep from the 2017-2020 National Health and Nutrition Examination Survey (NHANES) (n = 8356, age ≥18 y). Multivariable logistic regression was used to examine associations between quintiles of blood Mn concentrations and subjective sleep outcomes (short sleep duration, late sleep midpoint, trouble sleeping, and obstructive sleep apnea [OSA] symptoms), adjusting for age, gender, body mass index, race/ethnicity, income, smoking, inflammation-adjusted serum ferritin concentration (iron status), caffeine, and alcohol intake. Gender-stratified models were used due to interactions with gender.

RESULTS

The mean (SE) blood Mn concentration was 9.7 (0.1) μg/L in US adults. In males, a nonlinear association was noted in the relationship between blood Mn levels and short sleep duration on weekdays and weekends. The third Mn quintile (Q3) group had lower odds of short sleep duration (<7 h) on weekdays (odds ratio [OR]=0.6, 95% confidence interval [CI]: 0.4, 0.9) than the lowest Mn quintile (Q1, reference) after adjusting for covariates in males. The second Mn quintile (Q2) group had lower odds of late sleep midpoint on weekdays than Q1 (OR=0.6, 95% CI: 0.4, 0.8). In females, Q2 group had lower odds of OSA symptoms than Q1 (OR: 0.6, 95% CI: 0.4, 0.9). No relationship was noted between Mn and trouble sleeping.

CONCLUSIONS

Gender differences exist in the association between Mn and sleep in adults. Q1 group had the poorest sleep outcomes, including higher odds of short sleep duration (in males), late sleep midpoint (in males), and OSA symptoms (in females).

Vitamin E protects dopaminergic neurons against manganese-induced neurotoxicity through stimulation of CHRM1 and KCNJ4

BACKGROUND

Manganese (Mn) overexposure can induce neurotoxicity and lead to manganism. Vitamin E (Vit E) has neuroprotective effects by acting as an ROS scavenger, preventing mitochondrial dysfunction and neuronal apoptosis. However, the effects of Vit E on Mn-induced nigrostriatal system lesions remains unknown.

OBJECTIVES

We aim to investigate whether Vit E has protective effects on Mn-induced nigrostriatal system lesions and mRNA expression profiles in the SN of mice.

METHODS

Sixty 8-week-old C57BL/6 male mice were randomly divided into the Control, MnCl2, MnCl2 +Vit E, and Vit E group. Twenty-four hours after the last injection, the behaviour test was performed. The numbers of dopaminergic neurons in Substantia nigra (SN), the contents of dopamine and its metabolite levels in striatium, and the morphology of mitochondria and nuclei in the dopaminergic neurons in SN were detected by immunofluorescence staining, high-performance liquid chromatography, and transmission electron microscopy. Transcriptome analysis was used to analyze the signaling pathways and RT-PCR was used to verify the mRNA levels.

RESULTS

Vit E ameliorates behavioral disorders and attenuates the loss of nigral dopaminergic neurons in the Mn-induced mouse model. In addition, Vit E antagonized Mn-induced toxicity by restoring mitochondrial function. The results of transcriptome sequencing and RTPCR show that the protective effect of Vit E was related to the upregulation of CHRM1 and KCNJ4 mRNA in the SN.

CONCLUSIONS

Vit E has neuroprotective effects on Mn-induced neurodegeneration in the nigrostriatal system. This effect may be related to the upregulation of CHRM1 and KCNJ4 mRNA stimulated by Vit E in the SN.

Exposure to the environmentally relevant fungicide Maneb: Studying toxicity in the soil nematode Caenorhabditis elegans

Maneb is a manganese-containing ethylene bisdithiocarbamate fungicide and is still commonly used as no cases of resistance have been documented. However, studies have shown that Maneb exposure has neurodegenerative potential in mammals, resulting in symptoms affecting the motor system. Despite its extensive use, structural elucidation of Maneb has only recently been accomplished by our group. This study aimed to examine the bioavailability of Maneb, the quantification of oxidative stress-related endpoints and neurotransmitters employing pure Maneb, its metabolites and structural analogues, in the model organism Caenorhabditis elegans. Exposure to Maneb did not increase the bioavailability of Mn compared to manganese chloride, although Maneb was about 8 times more toxic with regard to lethality. Maneb generated not significantly reactive oxygen and nitrogen species (RONS) but decreased the ATP level while increasing the amount of glutathione and its oxidized form in a dose-dependent manner. Nevertheless, an alteration in the neurotransmitter homeostasis of dopamine, acetylcholine, and gamma-butyric acid (GABA) was observed as well as morphological changes in the dopaminergic neurons upon Maneb exposure, which underlines the assumption of the neurotoxic potential of Maneb. This study showed that Maneb exhibits effects based on a combined interaction of the ligand and manganese.

MnO2 nanoparticles trigger hepatic lipotoxicity and mitophagy via mtROS-dependent Hsf1Ser326 phosphorylation

Manganese (Mn) is an essential element for maintaining normal metabolism in vertebrates. Mn dioxide nanoparticles (MnO2 NPs), a novel Mn source, have shown great potentials in biological and biomedical applications due to their distinct physical and chemical properties. However, little is known about potential adverse effects on animal or cellular metabolism. Here, we investigated whether and how dietary MnO2 NPs affect hepatic lipid metabolism in vertebrates. We found that, excessive MnO2 NPs intake increased hepatic and mitochondrial Mn content, promoted hepatic lipotoxic disease and lipogenesis, and inhibited hepatic lipolysis and fatty acid β-oxidation. Moreover, excessive MnO2 NPs intake induced hepatic mitochondrial oxidative stress, damaged mitochondrial function, disrupted mitochondrial dynamics and activated mitophagy. Importantly, we uncovered that mtROS-activated phosphorylation of heat shock factor 1 (Hsf1) at Ser326 residue mediated MnO2 NPs-induced hepatic lipotoxic disease and mitophagy. Mechanistically, MnO2 NPs-induced lipotoxicity and mitophagy were via mtROS-induced phosphorylation and nucleus translocation of Hsf1 and its DNA binding capacity to plin2/dgat1 and bnip3 promoters, respectively. Overall, our findings uncover novel mechanisms by which mtROS-mediated mitochondrial dysfunction and phosphorylation of Hsf1S326 contribute to MnO2 NPs-induced hepatic lipotoxicity and mitophagy, which provide new insights into the effects of metal oxides nanoparticles on hepatotoxicity in vertebrates.

Manganese in residential drinking water from a community-initiated case study in Massachusetts

BACKGROUND

Manganese (Mn) is a metal commonly found in drinking water, but the level that is safe for consumption is unknown. In the United States (U.S.), Mn is not regulated in drinking water and data on water Mn concentrations are temporally and spatially sparse.

OBJECTIVE

Examine temporal and spatial variability of Mn concentrations in repeated tap water samples in a case study of Holliston, Massachusetts (MA), U.S., where drinking water is pumped from shallow aquifers that are vulnerable to Mn contamination.

METHODS

We collected 79 residential tap water samples from 21 households between September 2018 and December 2019. Mn concentrations were measured using inductively coupled plasma mass spectrometry. We calculated descriptive statistics and percent of samples exceeding aesthetic (secondary maximum containment level; SMCL) and lifetime health advisory (LHA) guidelines of 50 µg/L and 300 µg/L, respectively. We compared these concentrations to concurrent and historic water Mn concentrations from publicly available data across MA.

RESULTS

The median Mn concentration in Holliston residential tap water was 2.3 µg/L and levels were highly variable (range: 0.03-5,301.8 µg/L). Mn concentrations exceeded the SMCL and LHA in 14% and 12% of samples, respectively. Based on publicly available data across MA from 1994-2022, median Mn concentration was 17.0 µg/L (N = 37,210; range: 1-159,000 µg/L). On average 40% of samples each year exceeded the SMCL and 9% exceeded the LHA. Samples from publicly available data were not evenly distributed between MA towns or across sampling years.

IMPACT STATEMENT

This study is one of the first to examine Mn concentrations in drinking water both spatially and temporally in the U.S. Findings suggest that concentrations of Mn in drinking water frequently exceed current guidelines and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible subpopulations like children. Future studies that comprehensively examine exposure to Mn in drinking water and its associations with children's health are needed to protect public health.

Butyrate Protects and Synergizes with Nicotine against Iron- and Manganese-induced Toxicities in Cell Culture

Toxic exposures to heavy metals, such as iron (Fe) and manganese (Mn), can result in long-range neurological diseases and are therefore of significant environmental and medical concerns. We have previously reported that damage to neuroblastoma-derived dopaminergic cells (SH-SY5Y) by both Fe and Mn could be prevented by pre-treatment with nicotine. Moreover, butyrate, a short chain fatty acid (SCFA) provided protection against salsolinol, a selective dopaminergic toxin, in the same cell line. Here, we broadened the investigation to determine whether butyrate might also protect against Fe and/or Mn, and whether, if combined with nicotine, an additive or synergistic effect might be observed. Both butyrate and nicotine concentration-dependently blocked Fe and Mn toxicities. Ineffective concentrations of nicotine and butyrate, when combined, provided full protection against both Fe and Mn. Moreover, the effects of nicotine but not butyrate could be blocked by mecamylamine, a non-selective nicotinic antagonist. On the other hand, the effects of butyrate, but not nicotine, could be blocked by beta-hydroxy butyrate, a fatty acid-3 receptor antagonist. These results not only provide further support for neuroprotective effects of both nicotine and butyrate but also indicate distinct mechanisms of action for each one. Furthermore, potential utility of butyrate and nicotine combination against heavy metal toxicities is suggested.

Metals in Cow Milk and Soy Beverages: Is There a Concern?

Nowadays, there is an increased consumption of plant-based protein beverages like soy beverages (SBs) as substitutes for cow milk (CM). Both accumulate toxic metals like lead (Pb), cadmium (Cd), and manganese (Mn), which, although essential, are neurotoxic at high levels. Metals can also perturb the normal development of children. This work aimed to evaluate these metal concentrations in CM and SB purchased on the Portuguese market. After validation of the method, linearity of calibration curves, work range, detection and quantification limits, and selectivity, metals were determined in 14 CM and 14 SB brands using atomic absorption spectrometry. The values were compared between CM and SB and with permissible limit values. Soy beverages had significantly (p < 0.05) higher concentrations of Cd (5.6 ± 4.2 µg/L) and Mn (117.4 ± 30.3) µg/L) than CM (2.15 ± 1.84 µg/L and 5.93 ± 1.21 µg/L, respectively); the Pb concentrations in CM (19.3 ± 12.1 µg/L) were not significantly (p > 0.05) higher than in SB (13.4 ± 9.6 µg/L). These values were similar to other studies and close to but under permissible limit values. Nevertheless, due to the toxicity and bioaccumulation of metals, the fact that these foods are routinely ingested by all ages, mainly children, and represent key ingredients in many processed foods, including baby foods, we suggest strict surveying of metal levels in CM and SBs.

Use of physiologically based pharmacokinetic modeling to support development of an acute (24-hour) health-based inhalation guideline for manganese

The toxicokinetics of manganese (Mn) are controlled through homeostasis because Mn is an essential element. However, at elevated doses, Mn is also neurotoxic and has been associated with respiratory, reproductive, and developmental effects. While health-based criteria have been developed for chronic inhalation exposure to ambient Mn, guidelines for short-term (24-h) environmental exposure are also needed. We reviewed US state, federal, and international health-based inhalation toxicity criteria, and conducted a literature search of recent publications. The studies deemed most appropriate to derive a 24-h guideline have a LOAEL of 1500 μg/m3 for inflammatory airway changes and biochemical measures of oxidative stress in the brain following 90 total hours of exposure in monkeys. We applied a cumulative uncertainty factor of 300 to this point of departure, resulting in a 24-h guideline of 5 μg/m3. To address uncertainty regarding potential neurotoxicity, we used a previously published physiologically based pharmacokinetic model for Mn to predict levels of Mn in the brain target tissue (i.e., globus pallidus) for exposure at 5 μg/m3 for two short-term human exposure scenarios. The PBPK model predictions support a short-term guideline of 5 μg/m3 as protective of both respiratory effects and neurotoxicity, including exposures of infants and children.

Associations of plasma manganese with adverse pregnancy outcomes: Nested case-control studies in a Chinese birth cohort

Both insufficient and excessive manganese exposure are associated with adverse pregnancy outcomes. However, no systematic research has established a standardized reference range for manganese levels with the consideration of the associated health risks during pregnancy. To verify the associations of prenatal manganese exposure with adverse outcomes and to identify a proper reference range for manganese based on health risks, we designed three nested case-control studies on three adverse outcomes including hypertensive disorders of pregnancy (HDP), preterm birth (PTB), and low birth weight (LBW) to investigate the associations with manganese levels. Plasma manganese concentrations in early pregnancy were measured. Conditional logistic regression analyses were used to estimate the associations of manganese levels with adverse outcomes. Restricted cubic spline (RCS) models were used to characterize the dose-response relationship of manganese and each outcome. Nonlinear associations were observed for manganese and adverse outcomes. Compared with women in the middle tertile of plasma manganese, we found that those in the highest tertile had a significantly higher risk of HDP (OR = 1.72, 95% CI: 1.02 to 2.89), that women in the lowest tertile had almost a tripled risk of delivering LBW infants (OR = 2.93, 95% CI: 1.67 to 5.17), and that women both in the lowest and the highest tertiles had significantly higher risks of PTB [OR = 1.83 (95% CI: 1.14 to 2.95); OR = 1.70 (95% CI: 1.05 to 2.76)]. U-shaped associations were found between plasma manganese and risk of PTB and infant LBW. Based on the results of RCS models, we identified a proper plasma manganese range of 1.72-3.18 μg/L, with relatively lower risks of adverse pregnancy outcomes. In conclusion, our study found U-shaped associations between manganese exposure and adverse pregnancy outcomes, and provided an optimal range of manganese concentration for pregnant women, based on health risk considerations.

Targeting ferroptosis by poly(acrylic) acid coated Mn3O4 nanoparticles alleviates acute liver injury

Ferroptosis, a newly characterized form of regulated cell death, is induced by excessive accumulation of lipid peroxidation catalyzed by intracellular bioactive iron. Increasing evidence has suggested that ferroptosis is involved in the pathogenesis of several human diseases, including acute liver injury. Targeted inhibition of ferroptosis holds great promise for the clinical treatment of these diseases. Herein, we report a simple and one-pot synthesis of ultrasmall poly(acrylic) acid coated Mn3O4 nanoparticles (PAA@Mn3O4-NPs, PMO), which perform multiple antioxidant enzyme-mimicking activities and can scavenge broad-spectrum reactive oxygen species. PMO could potently suppress ferroptosis. Mechanistically, after being absorbed mainly through macropinocytosis, PMO are largely enriched in lysosomes, where PMO detoxify ROS, inhibit ferritinophagy-mediated iron mobilization and preserve mTOR activation, which collectively confer the prominent inhibition of ferroptosis. Additionally, PMO injection potently counteracts lipid peroxidation and alleviates acetaminophen- and ischaemia/reperfusion-induced acute liver injury in mice. Collectively, our results reveal that biocompatible PMO act as potent ferroptosis inhibitors through multifaceted mechanisms, which ensures that PMO have great translational potential for the clinical treatment of ferroptosis-related acute liver injury.

Improvement of nutritional properties of regular and gluten-free cakes with composite flour

This study was carried out to develop regular and gluten-free cakes with the high nutritional and functional value from composite flours. Composite flour was prepared by blending of equal amounts of chestnut, lupine and pumpkin flour. Wheat flour (for regular cake) and corn starch: rice flour blend (for gluten-free cake) used in cake formulation were replaced with composite flour in ratios of 9, 18, 27 and 36%, respectively. Composite flour had a significant (p < 0.05) effect on all color parameters of the crust and crumb of regular and gluten-free cake samples. Cake weight and hardness values increased with the use of composite flour in regular and gluten-free cake samples, and higher weight and hardness values were determined in gluten-free cakes. High composite flour ratios (27-36%) resulted in the lowest cake volume in both cakes. The gluten-free cake had lower ash, protein, antioxidant activity and total phenolic content (TPC) compared to the regular cake. The composite flour usage increased the ash, protein, antioxidant activity, TPC, and mineral contents of both cake samples. When the nutritional, functional, technological and sensory properties of cakes were evaluated together, it was concluded that the use of 9% composite flour was the most appropriate ratio for both cake types.

Therapeutic application of manganese-based nanosystems in cancer radiotherapy

Radiotherapy is an important therapeutic modality in the treatment of cancers. Nevertheless, the characteristics of the tumor microenvironment (TME), such as hypoxia and high glutathione (GSH), limit the efficacy of radiotherapy. Manganese-based (Mn-based) nanomaterials offer a promising prospect for sensitizing radiotherapy due to their good responsiveness to the TME. In this review, we focus on the mechanisms of radiosensitization of Mn-based nanosystems, including alleviating tumor hypoxia, increasing reactive oxygen species production, increasing GSH conversion, and promoting antitumor immunity. We further illustrate the applications of these mechanisms in cancer radiotherapy, including the development and delivery of radiosensitizers, as well as their combination with other therapeutic modalities. Finally, we summarize the application of Mn-based nanosystems as contrast agents in realizing precision therapy. Hopefully, the present review will provide new insights into the biological mechanisms of Mn-based nanosystems, as well as their applications in radiotherapy, in order to address the difficulties and challenges that remain in their clinical application in the future.

Early-life manganese exposure during multiple developmental periods and adolescent verbal learning and memory

BACKGROUND

Manganese (Mn) is both an essential and toxic metal, and associations with neurodevelopment depend on exposure timing. Prospective data examining early life Mn with adolescent cognition are sparse.

METHODS

We enrolled 140 Italian adolescents (10-14 years old) from the Public Health Impact of Metals Exposure study. Mn in deciduous teeth was measured using laser ablation-mass spectrometry to represent prenatal, postnatal and early childhood exposure. The California Verbal Learning Test for Children (CVLT-C) was administered to assess adolescent verbal learning and memory. Multivariable regression models estimated changes in CVLT-C scores and the odds of making an error per doubling in dentine Mn in each exposure period. Multiple informant models tested for differences in associations across exposure periods.

RESULTS

A doubling in prenatal dentine Mn levels was associated with lower odds of making an intrusion error (OR = 0.23 [95% CI: 0.09, 0.61]). This beneficial association was not observed in other exposure periods. A doubling in childhood Mn was beneficially associated with short delay free recall: (ß = 0.47 [95% CI: -0.02, 0.97]), which was stronger in males (ß = 0.94 [95% CI: 0.05, 1.82]). Associations were null in the postnatal period.

CONCLUSION

Exposure timing is critical for understanding Mn-associated changes in cognitive function.

Manganese regulation of COPII condensation controls circulating lipid homeostasis

Precise control of circulating lipids is instrumental in health and disease. Bulk lipids, carried by specialized lipoproteins, are secreted into the circulation, initially via the coat protein complex II (COPII). How the universal COPII machinery accommodates the abundant yet unconventional lipoproteins remains unclear, let alone its therapeutic translation. Here we report that COPII uses manganese-tuning, self-constrained condensation to selectively drive lipoprotein delivery and set lipid homeostasis in vivo. Serendipitously, adenovirus hijacks the condensation-based transport mechanism, thus enabling the identification of cytosolic manganese as an unexpected control signal. Manganese directly binds the inner COPII coat and enhances its condensation, thereby shifting the assembly-versus-dynamics balance of the transport machinery. Manganese can be mobilized from mitochondria stores to signal COPII, and selectively controls lipoprotein secretion with a distinctive, bell-shaped function. Consequently, dietary titration of manganese enables tailored lipid management that counters pathological dyslipidaemia and atherosclerosis, implicating a condensation-targeting strategy with broad therapeutic potential for cardio-metabolic health.

Environmental tobacco smoke exposure is associated with increased levels of metals in children's saliva

BACKGROUND

Exposure to environmental tobacco smoke (ETS) has been associated with detectable levels of cotinine (a nicotine metabolite) in children's saliva. However, tobacco smoke also contains toxic and essential trace metals, including chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn).

OBJECTIVE

The current study examines whether there is a relationship between ETS exposure, as gauged by salivary cotinine, and salivary levels of these metals in a subset (n = 238) of children from the Family Life Project.

METHODS

Using inductively-coupled-plasma optical emission spectrophotometry, we measured levels of metals in saliva from children at ~90 months of age. Salivary cotinine was measured using a commercial immunoassay.

RESULTS

We found that Cr, Cu, Mn, and Zn were detected in most samples (85-99%) with lower levels of detection for Pb and Ni (9.3% and 13.9% respectively). There were no significant differences in any of the metal concentrations between males and females, nor were levels associated with body mass index, although significant differences in salivary Cr and Mn by race, state and income-to-needs ratio were observed. Children with cotinine levels >1 ng/ml had higher levels of Zn (b = 0.401, 95% CI: 0.183 to 0.619; p = 0.0003) and Cu (b = 0.655, 95% CI: 0.206 to 1.104; p = 0.004) compared to children with levels <1 ng/ml, after controlling for multiple confounders, including sex, race, BMI and income-to-needs ratio. Further, we show that children whose cotinine levels were >1 μg/L were more likely to have detectable levels of Pb in their saliva (b = 1.40, 95% CI: 0.424 to 2.459; p = 0.006) compared to children with cotinine levels <1 ng/ml, also considering confounders.

IMPACT STATEMENT

This is the first study to demonstrate significant associations between salivary cotinine and salivary levels of Cu, Zn and Pb, suggesting that environmental tobacco smoke exposure my be one source of increased children's exposure to heavy metals. This study also demonstrates that saliva samples can be used to measure heavy metal exposure, and thus serve as a non-invasive tool for assessing a broader range of risk indicators.

Common and Trace Metals in Alzheimer's and Parkinson's Diseases

Trace elements and metals play critical roles in the normal functioning of the central nervous system (CNS), and their dysregulation has been implicated in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). In a healthy CNS, zinc, copper, iron, and manganese play vital roles as enzyme cofactors, supporting neurotransmission, cellular metabolism, and antioxidant defense. Imbalances in these trace elements can lead to oxidative stress, protein aggregation, and mitochondrial dysfunction, thereby contributing to neurodegeneration. In AD, copper and zinc imbalances are associated with amyloid-beta and tau pathology, impacting cognitive function. PD involves the disruption of iron and manganese levels, leading to oxidative damage and neuronal loss. Toxic metals, like lead and cadmium, impair synaptic transmission and exacerbate neuroinflammation, impacting CNS health. The role of aluminum in AD neurofibrillary tangle formation has also been noted. Understanding the roles of these elements in CNS health and disease might offer potential therapeutic targets for neurodegenerative disorders. The Codex Alimentarius standards concerning the mentioned metals in foods may be one of the key legal contributions to safeguarding public health. Further research is needed to fully comprehend these complex mechanisms and develop effective interventions.

Association between Mineral Intake and Cognition Evaluated by Montreal Cognitive Assessment (MoCA): A Cross-Sectional Study

BACKGROUND

Mineral intake may protect against cognitive impairment (CI) and all-cause dementia, which affects a large number of adults worldwide. The aim of this study was to investigate the association between mineral intake and Montreal Cognitive Assessment (MoCA), which is a sensitive and specific test.

METHODS

In total, 201 adults were included in a cross-sectional study. They completed a three-day dietary record to estimate their average daily intake of minerals. Contributions to dietary reference intakes (DRIs) were also calculated. The participants were divided into tertiles according to their mineral intake. CI classifications were determined via the MoCA (score < 26). Apolipoprotein E (APOE) genotyping was carried out, and the patients' anthropometric measurements and physical activity, health and personal data were collected.

RESULTS

The prevalence of CI in this selective sample was 54.2% (34.3% females and 19.9% males). In women, being in the third tertiles of iron and manganese intake was associated with lower odds of having CI (OR [95% CI]: 0.32 [0.11 ± 0.93]; 0.33 [0.12 ± 0.93], p < 0.05). No significant differences were observed for any of the nutrients studied in men.

CONCLUSIONS

These findings suggest that a low mineral intake, especially low iron and manganese intake in women, is associated with a worse cognition as assessed by MoCA.

Essential Trace Elements Status in Portuguese Pregnant Women and Their Association with Maternal and Neonatal Outcomes: A Prospective Study from the IoMum Cohort

Cobalt (Co), copper (Cu), manganese (Mn), molybdenum (Mo), and zinc (Zn) are essential trace elements (ETEs) and important cofactors for intermediary metabolism or redox balance. These ETEs are crucial during pregnancy, their role on specific pregnancy outcomes is largely unknown. This prospective study (#NCT04010708) aimed to assess urinary levels of these ETEs in pregnancy and to evaluate their association with pregnancy outcomes. First trimester pregnant women of Porto and Lisbon provided a random spot urine sample, and sociodemographic and lifestyle data. Clinical data were obtained from clinical records. Urinary ETEs were quantified by inductively coupled plasma mass spectrometry (ICP-MS). A total of 635 mother:child pairs were included. Having urinary Zn levels above the 50th percentile (P50) was an independent risk factor for pre-eclampsia (PE) (aOR [95% CI]: 5.350 [1.044-27.423], p = 0.044). Urinary Zn levels above the P50 decreased the risk of small for gestational age (SGA) birth head circumference (aOR [95% CI]: 0.315 [0.113-0.883], p = 0.028), but it increased the risk SGA length (aOR [95% CI]: 2.531 [1.057-6.062], p = 0.037). This study may provide valuable information for public health policies related to prenatal nutrition, while informing future efforts to de-fine urinary reference intervals for ETEs in pregnant women.

Consequences of Disturbing Manganese Homeostasis

Manganese (Mn) is an essential trace element with unique functions in the body; it acts as a cofactor for many enzymes involved in energy metabolism, the endogenous antioxidant enzyme systems, neurotransmitter production, and the regulation of reproductive hormones. However, overexposure to Mn is toxic, particularly to the central nervous system (CNS) due to it causing the progressive destruction of nerve cells. Exposure to manganese is widespread and occurs by inhalation, ingestion, or dermal contact. Associations have been observed between Mn accumulation and neurodegenerative diseases such as manganism, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. People with genetic diseases associated with a mutation in the gene associated with impaired Mn excretion, kidney disease, iron deficiency, or a vegetarian diet are at particular risk of excessive exposure to Mn. This review has collected data on the current knowledge of the source of Mn exposure, the experimental data supporting the dispersive accumulation of Mn in the brain, the controversies surrounding the reference values of biomarkers related to Mn status in different matrices, and the competitiveness of Mn with other metals, such as iron (Fe), magnesium (Mg), zinc (Zn), copper (Cu), lead (Pb), calcium (Ca). The disturbed homeostasis of Mn in the body has been connected with susceptibility to neurodegenerative diseases, fertility, and infectious diseases. The current evidence on the involvement of Mn in metabolic diseases, such as type 2 diabetes mellitus/insulin resistance, osteoporosis, obesity, atherosclerosis, and non-alcoholic fatty liver disease, was collected and discussed.

Butyrate protects and synergizes with nicotine against iron- and manganese-induced toxicities in cell culture: Implications for neurodegenerative diseases

Toxic exposures to heavy metals, such as iron (Fe) and manganese (Mn), can result in long-range neurological diseases and are therefore of significant environmental and medical concerns. We have previously reported that damage to neuroblastoma-derived dopaminergic cells (SH-SY5Y) by both Fe and Mn could be prevented by pre-treatment with nicotine. Moreover, butyrate, a short chain fatty acid (SCFA) provided protection against salsolinol, a selective dopaminergic toxin, in the same cell line. Here, we broadened the investigation to determine whether butyrate might also protect against Fe and/or Mn, and whether, if combined with nicotine, an additive or synergistic effect might be observed. Both butyrate and nicotine concentration-dependently blocked Fe and Mn toxicities. The ineffective concentrations of nicotine and butyrate, when combined, provided full protection against both Fe and Mn. Moreover, the effects of nicotine but not butyrate could be blocked by mecamylamine, a non-selective nicotinic antagonist. On the other hand, the effects of butyrate, but not nicotine, could be blocked by beta-hydroxy butyrate, a fatty acid-3 receptor antagonist. These results not only provide further support for neuroprotective effects of both nicotine and butyrate but indicate distinct mechanisms of action for each one. Furthermore, potential utility of the combination of butyrate and nicotine against heavy metal toxicities is suggested.

Manganese overexposure induces Parkinson-like symptoms, altered lipid signature and oxidative stress in C57BL/6 J mouse

Although adequate intake of manganese (Mn) is essential to humans, Mn in excess is neurotoxic. Exposure to extremely high doses of Mn results in "manganism", a condition that exhibits Parkinson-like symptoms. However, the mechanisms underlying its neurotoxic effects in Mn-induced parkinsonism pathogenesis are unclear. In this study, 8-week-old male C57BL/6 J mice were injected intraperitoneally with saline and 50 mg/kg MnCl2 respectively once daily for 14 days to produce an acute Mn neurotoxicity model. Accumulation of Mn in the midbrain, motor dysfunction and loss of dopaminergic neurons in the substantia nigra evidenced Mn neurotoxicity. Untargeted lipidomic analysis demonstrated that Mn overexposure altered lipidome profiles. A significant modulation of 12 lipid subclasses belonging to 5 different categories were found in the midbrain and among the most abundant lipids were sphingolipids, glycerophospholipids, and glycerides. The levels of sphingomyelin (SM) were significantly decreased after Mn treatment. The expression of SM biosynthesis genes was decreased dramatically while sphingomyelinase was up-regulated. In addition, we observed oxidative stress in both the midbrain of mice and MN9D cells, indicated by the increase of MDA level, the decrease of reduced GSH level and the inhibition of SOD and GPx enzyme activities. There was a correlation between these changes and motor dysfunctions. Overall, our study is the first to use lipidomics techniques to explore the pathogenesis of Mn-induced parkinsonism in C57BL/6 J mice. Mn induced molecular events in the midbrain, such as lipid metabolism disorders, oxidative stress and dopaminergic neurons injury, may mechanistically play important roles in the pathogenesis of Parkinson-like symptoms. Moreover, these findings emphasize the necessity for reducing the health risk of environmental neurotoxic pollutants in relation to parkinsonism.

Trace metal elements: a bridge between host and intestinal microorganisms

Trace metal elements, such as iron, copper, manganese, and zinc, are essential nutrients for biological processes. Although their intake demand is low, they play a crucial role in cell homeostasis as the cofactors of various enzymes. Symbiotic intestinal microorganisms compete with their host for the use of trace metal elements. Moreover, the metabolic processes of trace metal elements in the host and microorganisms affect the organism's health. Supplementation or the lack of trace metal elements in the host can change the intestinal microbial community structure and function. Functional changes in symbiotic microorganisms can affect the host's metabolism of trace metal elements. In this review, we discuss the absorption and transport processes of trace metal elements in the host and symbiotic microorganisms and the effects of dynamic changes in the levels of trace metal elements on the intestinal microbial community structure. We also highlight the participation of trace metal elements as enzyme cofactors in the host immune process. Our findings indicate that the host uses metal nutrition immunity or metal poisoning to resist pathogens and improve immunity.

A State-of-the-Science Review on Metal Biomarkers

PURPOSE OF REVIEW

Biomarkers are commonly used in epidemiological studies to assess metals and metalloid exposure and estimate internal dose, as they integrate multiple sources and routes of exposure. Researchers are increasingly using multi-metal panels and innovative statistical methods to understand how exposure to real-world metal mixtures affects human health. Metals have both common and unique sources and routes of exposure, as well as biotransformation and elimination pathways. The development of multi-element analytical technology allows researchers to examine a broad spectrum of metals in their studies; however, their interpretation is complex as they can reflect different windows of exposure and several biomarkers have critical limitations. This review elaborates on more than 500 scientific publications to discuss major sources of exposure, biotransformation and elimination, and biomarkers of exposure and internal dose for 12 metals/metalloids, including 8 non-essential elements (arsenic, barium, cadmium, lead, mercury, nickel, tin, uranium) and 4 essential elements (manganese, molybdenum, selenium, and zinc) commonly used in multi-element analyses.

RECENT FINDINGS

We conclude that not all metal biomarkers are adequate measures of exposure and that understanding the metabolic biotransformation and elimination of metals is key to metal biomarker interpretation. For example, whole blood is a good biomarker of exposure to arsenic, cadmium, lead, mercury, and tin, but it is not a good indicator for barium, nickel, and uranium. For some essential metals, the interpretation of whole blood biomarkers is unclear. Urine is the most commonly used biomarker of exposure across metals but it should not be used to assess lead exposure. Essential metals such as zinc and manganese are tightly regulated by homeostatic processes; thus, elevated levels in urine may reflect body loss and metabolic processes rather than excess exposure. Total urinary arsenic may reflect exposure to both organic and inorganic arsenic, thus, arsenic speciation and adjustment for arsebonetaine are needed in populations with dietary seafood consumption. Hair and nails primarily reflect exposure to organic mercury, except in populations exposed to high levels of inorganic mercury such as in occupational and environmental settings. When selecting biomarkers, it is also critical to consider the exposure window of interest. Most populations are chronically exposed to metals in the low-to-moderate range, yet many biomarkers reflect recent exposures. Toenails are emerging biomarkers in this regard. They are reliable biomarkers of long-term exposure for arsenic, mercury, manganese, and selenium. However, more research is needed to understand the role of nails as a biomarker of exposure to other metals. Similarly, teeth are increasingly used to assess lifelong exposures to several essential and non-essential metals such as lead, including during the prenatal window. As metals epidemiology moves towards embracing a multi-metal/mixtures approach and expanding metal panels to include less commonly studied metals, it is important for researchers to have a strong knowledge base about the metal biomarkers included in their research. This review aims to aid metals researchers in their analysis planning, facilitate sound analytical decision-making, as well as appropriate understanding and interpretation of results.

Hepatobiliary manganese homeostasis is dynamic in the setting of inflammation or infection in mice

Manganese is a diet-derived micronutrient that is essential for critical cellular processes like redox homeostasis, protein glycosylation, and lipid and carbohydrate metabolism. Control of Mn availability, especially at the local site of infection, is a key component of the innate immune response. Less has been elucidated about Mn homeostasis at the systemic level. In this work, we demonstrate that systemic Mn homeostasis is dynamic in response to inflammation and infection in mice. This phenomenon is evidenced in male and female mice, mice of two genetic backgrounds (C57BL/6 and BALB/c), in multiple models of acute (dextran sodium sulfate-induced) and chronic (enterotoxigenic Bacteroides fragilis) colitis, and systemic infection with Candida albicans. When mice were fed a standard corn-based chow with excess Mn (100 ppm), liver Mn decreased and biliary Mn increased threefold in response to infection or colitis. Liver iron, copper, and zinc were unchanged. When dietary Mn was restricted to minimally adequate amounts (10 ppm), baseline hepatic Mn levels decreased by approximately 60% in the liver, and upon induction of colitis, liver Mn did not decrease further, however, biliary Mn still increased 20-fold. In response to acute colitis, hepatic Slc39a8 mRNA (gene encoding the Mn importer, Zip8) and Slc30a10 mRNA (gene encoding the Mn exporter, Znt10) are decreased. Zip8 protein is decreased. Inflammation/infection-associated dynamic Mn homeostasis may represent a novel host immune/inflammatory response that reorganizes systemic Mn availability through differential expression of key Mn transporters with down-regulation of Zip8.

Exposure to manganese during sertoli cell formation and proliferation disturbs early testicular development in rats

Manganese (Mn) is a metal and important micronutrient. However, exposure to supraphysiological levels of Mn, which occur through fungicides, atmospheric emissions, drainages, and spills, has been related to health risks, including morphometric changes in the male reproductive organs and impairment on gametogenesis and sperm quality, impacting the fertile ability of adult animals. Despite the relevance of the fetal/perinatal period for toxicological studies on Mn, previous data only deal with the physical and neurological development of the offspring, without mentioning their reproductive development. The present study investigated whether exposure to Mn during fetal/perinatal phase, specifically during the period of formation and proliferation of Sertoli cells, impairs the reproductive development of male offspring in early postnatal life. Therefore, pregnant Wistar rats were randomly distributed into 3 experimental groups: Ctl (received saline solution), Mn-9 (received 9 mg/kg of MnCl2), and Mn-90 (received 90 mg/kg of MnCl2). The female rats received the experimental treatment by gavage from gestational day 13 to lactational day 15, i.e., postnatal day (PND) 15 of the pups. Oxidative damage to the genetic material of germ and Sertoli cells, together with a decrease in connexin 43 immunolabeling were observed in the testis of male pups evaluated at PND 15. In addition, an increase in the seminiferous tubules presenting slight epithelium vacuolization and cells with eosinophilic cytoplasm were observed, without apparent epididymal changes. In conclusion, it was demonstrated that Mn perturbed the initial testicular development by altering Sertoli cell integrity through oxidative insult, which may compromise the spermatogenesis in the long-term.