"Manganese-induced neurotoxicity: a review of its behavioral consequences and neuroprotective strategies"

Small extracellular vesicles-derived from 3d cultured human nasal mucosal mesenchymal stem cells during differentiation to dopaminergic progenitors promote neural damage repair via miR-494-3p after manganese exposed mice

Manganese (Mn) exposure is a common environmental risk factor for Parkinson's disease (PD), with pathogenic mechanisms associated with dopaminergic neuron damage and neuroinflammation. Mesenchymal stem cells (MSCs)-derived small extracellular vesicles (sEVs) have emerged as a novel therapeutic approach for neural damage repair. The functional sEVs released from MSCs when they are induced into dopaminergic progenitors may have a better repair effect on neural injury. Therefore, we collected sEVs obtained from primary human nasal mucosal mesenchymal stem cells (hnmMSC-sEVs) or cells in the process of dopaminergic progenitor cell differentiation (da-hnmMSC-sEVs), which were cultured in a 3D dynamic system, and observed their repair effects and mechanisms of Mn-induced neural damage by intranasal administration of sEVs. In Mn-exposed mice, sEVs could reach the site of brain injury after intranasal administration, da-hnmMSC enhanced the repair effects of sEVs in neural damage and behavioral competence, as evidenced by restoration of motor dysfunction, enhanced neurogenesis, decreased microglia activation, up-regulation of anti-inflammatory factors, and down-regulation of pro-inflammatory factors. The transcriptomics of hnmMSC-sEVs and da-hnmMSC-sEVs revealed that miRNAs, especially miR-494-3p in sEVs were involved in neuroprotective and anti-inflammatory effects. Overexpression of miR-494-3p in sEVs inhibited Mn-induced inflammation and neural injury, and its repair mechanism might be related to the down-regulation of CMPK2 and NLRP3 in vitro experiments. Thus, intranasal delivery of da-hnmMSC-sEVs is an effective strategy for the treatment of neural injury repair.

Nutritional profile and risk assessment of inorganic elements in enteral and parenteral nutrition formulas

The contents of essential (Ca, Fe, K, Na, P, and Zn) and potentially toxic inorganic elements (As, Al, Cd, Cr, Cu, Mn, and Pb) in enteral and parenteral nutrition formulas were evaluated by inductively coupled plasma optical emission spectrometry (ICP OES) and graphite furnace atomic absorption spectrometry (GFAAS). A total of 30 enteral formulas, 23 parenteral solution components, and 3 parenteral solutions were analyzed. The elements Ca and K presented the higher contents (72-2918 mg L-1 and 235-2760 mg L-1) while the lowest concentration levels were found for As and Cd (<0.68 µg L-1 and <0.01-0.62 µg L-1) in the studied samples. The validated analytical methods presented an accuracy of 75-116% and RSD values lower than 9.8%. Calcium gluconate and magnesium sulfate, which are used as raw materials in parenteral solution, are potential sources of Al and Mn contamination. A Hazard Quotient (HQ) >1 was obtained for Al (27 ± 1 µg L-1) in one of the parenteral samples, whereas the established limit is 25 µg L-1. Enteral samples were considered safe for consumption regarding the Al, As, and Cd levels. One healing-specific and pediatric formula contained Pb at levels above 0.25 µg kg-day-1, too high for safe consumption. The enteral formulas (pediatric, diabetes-specific, renal-specific, healing-specific, and standard formula with addition of fiber) presented risks in relation to the consumption of Cr and Mn (>250 µg day-1 and >11 mg day-1). The results indicate the need for strict monitoring, considering that these formulations are often the single patient's food source.

Neuroprotective Strategies and Cell-Based Biomarkers for Manganese-Induced Toxicity in Human Neuroblastoma (SH-SY5Y) Cells

Manganese (Mn) is an essential heavy metal in the human body, while excess Mn leads to neurotoxicity, as observed in this study, where 100 µM of Mn was administered to the human neuroblastoma (SH-SY5Y) cell model of dopaminergic neurons in neurodegenerative diseases. We quantitated pathway and gene changes in homeostatic cell-based adaptations to Mn exposure. Utilizing the Gene Expression Omnibus, we accessed the GSE70845 dataset as a microarray of SH-SY5Y cells published by Gandhi et al. (2018) and applied statistical significance cutoffs at p < 0.05. We report 74 pathway and 10 gene changes with statistical significance. ReactomeGSA analyses demonstrated upregulation of histones (5 out of 10 induced genes) and histone deacetylases as a neuroprotective response to remodel/mitigate Mn-induced DNA/chromatin damage. Neurodegenerative-associated pathway changes occurred. NF-κB signaled protective responses via Sirtuin-1 to reduce neuroinflammation. Critically, Mn activated three pathways implicating deficits in purine metabolism. Therefore, we validated that urate, a purine and antioxidant, mitigated Mn-losses of viability in SH-SY5Y cells. We discuss Mn as a hypoxia mimetic and trans-activator of HIF-1α, the central trans-activator of vascular hypoxic mitochondrial dysfunction. Mn induced a 3-fold increase in mRNA levels for antioxidant metallothionein-III, which was induced 100-fold by hypoxia mimetics deferoxamine and zinc.

Magnetic Resonance Imaging and Manganism: A Narrative Review and Laboratory Recommendations

In recent years, a series of articles has been published concerning magnetic resonance imaging (MRI) studies in a group of patients exposed to manganism, specifically factory workers, welders, and individuals with liver diseases, as well as those abusing home-produced ephedrone. Some potential symptoms of manganese toxicity include motor disturbances, neurocognitive problems, sleep disorders, and psychosocial changes. Despite various publications on MRI research in individuals with an elevated risk of manganism, there is a noticeable absence of a comprehensive review in this field. The detection of the accumulation of manganese in the brain through MRI can confirm the diagnosis and guide appropriate treatment. Due to the high cost of determining manganese ion levels in biological material, an additional aim of the manuscript was to identify simple medical laboratory parameters that, when performed concurrently with MRI, could assist in the diagnosis of manganism. Among these types of parameters are the levels of bilirubin, magnesium, liver enzymes, creatinine, hemoglobin, and hematocrit.

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.

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.

Trace Elements in Alzheimer's Disease and Dementia: The Current State of Knowledge

Changes in trace element concentrations are being wildly considered when it comes to neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. This study aims to present the role that trace elements play in the central nervous system. Moreover, we reviewed the mechanisms involved in their neurotoxicity. Low zinc concentrations, as well as high levels of copper, manganese, and iron, activate the signalling pathways of the inflammatory, oxidative and nitrosative stress response. Neurodegeneration occurs due to the association between metals and proteins, which is then followed by aggregate formation, mitochondrial disorder, and, ultimately, cell death. In Alzheimer's disease, low Zn levels suppress the neurotoxicity induced by β-amyloid through the selective precipitation of aggregation intermediates. High concentrations of copper, iron and manganese cause the aggregation of intracellular α-synuclein, which results in synaptic dysfunction and axonal transport disruption. Parkinson's disease is caused by the accumulation of Fe in the midbrain dopaminergic nucleus, and the pathogenesis of multiple sclerosis derives from Zn deficiency, leading to an imbalance between T cell functions. Aluminium disturbs the homeostasis of other metals through a rise in the production of oxygen reactive forms, which then leads to cellular death. Selenium, in association with iron, plays a distinct role in the process of ferroptosis. Outlining the influence that metals have on oxidoreduction processes is crucial to recognising the pathophysiology of neurodegenerative diseases and may provide possible new methods for both their avoidance and therapy.

Nucleic Acid Materials-Mediated Innate Immune Activation for Cancer Immunotherapy

Abnormally localized nucleic acids (NAs) are considered as pathogen associated molecular patterns (PAMPs) in innate immunity. They are recognized by NAs-specific pattern recognition receptors (PRRs), leading to the activation of associated signaling pathways and subsequent production of type I interferons (IFNs) and pro-inflammatory cytokines, which further trigger the adaptive immunity. Notably, NAs-mediated innate immune activation is highly dependent on the conformation changes, especially the aggregation of PRRs. Evidence indicates that the characteristics of NAs including their length, concentration and even spatial structure play essential roles in inducing the aggregation of PRRs. Therefore, nucleic acid materials (NAMs) with high valency of NAs and high-order structures hold great potential for activating innate and adaptive immunity, making them promising candidates for cancer immunotherapy. In recent years, a variety of NAMs have been developed and have demonstrated significant efficacy in achieving satisfactory anti-tumor immunity in multiple mouse models, exhibiting huge potential for clinical application in cancer treatment. This review aims to discuss the mechanisms of NAMs-mediated innate immune response, and summarize their applications in cancer immunotherapy.

In situ bio-mineralized Mn nanoadjuvant enhances anti-influenza immunity of recombinant virus-like particle vaccines

Virus like particles (VLPs) have been well recognized as one of the most important vaccine platforms due to their structural similarity to natural viruses to induce effective humoral and cellular immune responses. Nevertheless, lack of viral nucleic acids in VLPs usually leads the vaccine candidates less efficient in provoking innate immune against viral infection. Here, we constructed a biomimetic dual antigen hybrid influenza nanovaccines THM-HA@Mn with robust immunogenicity via in situ synthesizing a stimulator of interferon genes (STING) agonist Mn3O4 inside the cavity of a recombinant Hepatitis B core antigen VLP (HBc VLP) having fused SpyTag and influenza M2e antigen peptides (Tag-HBc-M2e, THM for short), followed by conjugating a recombinant hemagglutinin (rHA) antigen on the surface of the nanoparticles through SpyTag/SpyCatcher ligating. Such inside Mn3O4 immunostimulator-outside rHA antigen design, together with the chimeric M2e antigen on the HBc skeleton, enabled the synthesized hybrid nanovaccines THM-HA@Mn to well imitate the spatial distribution of M2e/HA antigens and immunostimulant in natural influenza virus. In vitro cellular experiments indicated that compared with the THM-HA antigen without Mn3O4 and a mixture vaccine consisting of THM-HA + MnOx, the THM-HA@Mn hybrid nanovaccines showed the highest efficacies in dendritic cells uptake and in promoting BMDC maturation, as well as inducing expression of TNF-α and type I interferon IFN-β. The THM-HA@Mn also displayed the most sustained antigen release at the injection site, the highest efficacies in promoting the DC maturation in lymph nodes and germinal center B cells activation in the spleen of the immunized mice. The co-delivery of immunostimulant and antigens enabled the THM-HA@Mn nanovaccines to induce the highest systemic antigen-specific antibody responses and cellular immunogenicity in mice. Together with the excellent colloid dispersion stability, low cytotoxicity, as well as good biosafety, the synthetic hybrid nanovaccines presented in this study offers a promising strategy to design VLP-based vaccine with robust natural and adaptive immunogenicity against emerging viral pathogens.

Polystyrene microplastics mitigate lead-induced neurotoxicity by reducing heavy metal uptake in zebrafish larvae

The combined pollution of lead (Pb) and polystyrene microplastics (PS-MPs) is common in aquatic environments. However, the combined neurotoxicity of these two pollutants is still poorly understood. In this study, zebrafish (Danio rerio) larvae were used to assess the combined neurotoxicity and mechanism of Pb and PS-MPs at environmentally relevant concentrations. The results showed that Pb (10 μg/L) induced abnormal behavior including significantly reduced movement distance, maximum acceleration, and average velocity (P < 0.05) along with altered expression of neurodevelopment-related genes (gap43 and α1-tubulin) (P < 0.05). PS-MPs (25 μg/L, 250 μg/L; diameter at 25 μm) co-exposure not only significantly reduced the concentration of Pb in the exposed solution (P < 0.01), but also decreased the uptake of Pb by downregulating the divalent metal transporter 1 gene (dmt1) (P < 0.01), thereby alleviating Pb-induced neurotoxicity. However, to demonstrate that PS-MPs alleviate the neurotoxicity of Pb by reducing Pb uptake, upregulation of dmt1 by addition of deferoxamine (DFO, an efficient iron chelator, 100 μM) significantly increased the Pb uptake and exacerbated neurotoxicity in zebrafish. In summary, our results demonstrated that PS-MPs alleviate Pb neurotoxicity by downregulating the mRNA level of dmt1 and decreasing the Pb uptake. This study provides a new insight into the combined neurotoxicity and underlying mechanisms of PS-MPs and Pb on zebrafish.

Diagnosis of manganism and manganese neurotoxicity: A workshop report

With declining exposures to manganese (Mn) in occupational settings, there is a need for more sensitive exposure assessments and clinical diagnostic criteria for manganism and Mn neurotoxicity. To address this issue, a workshop was held on November 12-13, 2020, with international experts on Mn toxicity. The workshop discussions focused on the history of the diagnostic criteria for manganism, including those developed by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST) in Quebec in 2005 and criteria developed by the Chinese government in 2002 and updated in 2006; the utility of biomarkers of exposure; recent developments in magnetic resonance imaging (MRI) for assessing Mn accumulation in the brain and diagnosing manganism; and potential future applications of metabolomics. The suggestions of the participants for updating manganism diagnostic criteria included the consideration of: i) A history of previous occupational and environmental exposure to Mn; ii) relevant clinical symptoms such as dystonia; iii) MRI imaging to document Mn accumulation in the neural tissues, including the basal ganglia; and iv) criteria for the differential diagnosis of manganism and other neurological conditions. Important research gaps include the characterization of Mn exposure and other co-exposures, exploration of the roles of different brain regions with MRI, understanding the complexity of metal ion transporters involved in Mn homeostasis, and a need for information on other neurotransmitter systems and brain regions underlying the pathophysiology of manganism.

Manganese-induced miR-125b-2-3p promotes anxiety-like behavior via TFR1-mediated ferroptosis

The toxic effects of excessive manganese (Mn) levels in the environment have led to a severe public health concern. Ferroptosis is a newly form of cell death relying on iron, inherent to pathophysiological processes of psychiatric disorders, such as anxiety and depression-like behaviors. Excessive Mn exposure causes various neurological effects, including neuronal death and mood disorders. Whether Mn exposure causes anxiety and depression-like behaviors, and the underlying mechanisms of Mn-induced ferroptosis have yet to be determined. Here, Mn-exposed mice showed anxiety-like behavior. We also confirmed the accumulation of ferrous ion (Fe2+), lipid peroxidation, and depletion of antioxidant defense system both in vitro and in vivo Mn-exposed models, suggesting that Mn exposure can induce ferroptosis. Furthermore, Mn exposure downregulated the expression of miR-125b-2-3p. In turn, overexpression of miR-125b-2-3p alleviated the Mn-induced ferroptosis by targeting Transferrin receptor protein 1 (TFR1). In summary, this novel study established the propensity of Mn to cause anxiety-like behavior, an effect that was regulated by miR-125b-2-3p and ensuing ferroptosis secondary to the targeting of TFR1. These results offer promising targets for the prevention and treatment of Mn-induced neurotoxicity.

Accumulation characteristics of metals in human breast milk and association with dietary intake in northeastern China

The trace elements present in breast milk play a vital role in the growth and development of infants. Nevertheless, numerous studies have reported the presence of toxic metal contamination in breast milk from various countries and regions, which poses potential risks to breastfed infants. This article aimed to investigate the characteristics of trace elements in breast milk and explore the relationship between breast milk and diet in Dalian, a coastal city in northeastern China. Breast milk samples and representative local food samples were collected from Dalian for research. The results revealed that 57 % of breast milk samples significantly exceeded the WHO safety limit (0.6 μg/L) for arsenic, with a measured mean value of 0.96 μg/L. Moreover, the levels of chromium (mean value: 2.63 μg/L) in 34 % of breast milk samples exceed the WHO recommended safety level (chromium: 1.5 μg/L). Aquatic foods accounted for 60 % to 90 % of the total intake of arsenic, cadmium, vanadium, mercury, and lead. The Spearman correlation analysis demonstrated strong positive correlations among breast milk metal elements, including copper-zinc (r = 0.68) and nickel‑chromium (r = 0.89). Furthermore, the food-to-milk accumulation factors (FMAF) of strontium, nickel, arsenic, vanadium, cadmium, and mercury were relatively low (median values <0.005). While the FMAF values for chromium and lead were higher, with median values of 0.038 and 0.07, respectively. The results indicated potential risks of the toxic metal arsenic in breast milk from Dalian, China for breastfed infants. Therefore, continuous monitoring of breast milk for toxic metals and foodborne contamination is necessary.

Single-cell transcriptomics analysis of zebrafish brain reveals adverse effects of manganese on neurogenesis

Manganese (Mn) is considered as an important environmental risk factor for Parkinson's disease. Excessive exposure to Mn can damage various neural cells and affect the neurogenesis, resulting in neurological dysfunction. However, the specific mechanisms of Mn exposure affecting neurogenesis have not been well understood, including compositional changes and heterogeneity of various neural cells. Zebrafish have been successfully used as a neurotoxicity model due to its homology with mammals in several key regions of the brain, as well as its advantages such as small size. We performed single-cell RNA sequencing of zebrafish brains from normal and Mn-exposed groups. Our results suggested that low levels of Mn exposure activated neurogenesis in the zebrafish brain, including promoting the proliferation of neural progenitor cells and differentiation to newborn neurons and oligodendrocytes, while high levels of Mn exposure inhibited neurogenesis and neural function. Mn could affect neurogenesis through specific molecular pathways. In addition, Mn regulated intercellular communication and affected cellular communication in neural cells through specific signaling pathways. Taken together, our study elucidates the cellular composition of the zebrafish brain and adds to the understanding of the mechanisms involved in Mn-induced neurogenesis damage.

Selenium and zinc protect against heavy metal mixture-induced, olfactory bulb and hippocampal damage by augmenting antioxidant capacity and activation of Nrf2-Hmox-1 signaling in male rats

PURPOSE/AIM OF THE STUDY

Heavy metals and metalloids have been implicated in neurodenerative diseases. Present study has evaluated the potential protective effects of Se and Zn on heavy metals and metalloids mixture-induced (Cd, Pb, Hg and As) toxicity in the hippocampus and olfactory bulb in male rats.

MATERIALS AND METHODS

Five groups of Wistar rats were randomly divided in to: controls, toxic metals mixture (TMM) exposed rats (PbCl2, 20 mg·kg-1; CdCl2, 1.61 mg·kg-1; HgCl2, 0.40 mg·kg-1 and NaAsO3, 10 mg·kg-1)), TMM + Zn, TMM + Se and TMM-+Zn + Se groups and were orally treated for 60 days.

RESULTS

We found that in hippocampus and olfactory bulb, TMM generated increased lipid peroxidation and diminished antioxidant capacity. These adverse effects induced by TMM were alleviated by Zn and Se co-treatment; moreover, essential trace elements (Zn and Se) decreased activity of acetylcholinesterase, reduced Cd, Pb, Hg and As bioaccumulation in hippocampus and olfactory bulb and decreased levels of TNF-α in the hippocampus. TMM treated rats had lower levels of Hmox-1 (hippocampus), higher levels of Nrf2 (olfactory bulb and hippocampus) and NF-kB (olfactory bulb). TMM treated rats showed significantly highest time in locating the escape hole. Histopathological examination revealed hypertrophied granule cells in OB of TMM exposed rats.

CONCLUSION

Zn and Se supplementation can reverse quaternary mixture-induced (Cd, Pb, Hg and As) toxicity in hippocampus and OB in male albino rats.

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.

Early life manganese exposure and reported attention-related behaviors in Italian adolescents

Background

Manganese (Mn) is an essential nutrient and neurotoxicant, and the neurodevelopmental effects of Mn may depend on exposure timing. Less research has quantitatively compared the impact of Mn exposure on neurodevelopment across exposure periods.

Methods

We used data from 125 Italian adolescents (10-14 years) from the Public Health Impact of Metals Exposure Study to estimate prospective associations of Mn in three early life exposure periods with adolescent attention-related behaviors. Mn was quantified in deciduous teeth using laser ablation-inductively coupled plasma-mass spectrometry to represent prenatal (2nd trimester-birth), postnatal (birth ~1.5 years), and childhood (~1.5-6 years) exposure. Attention-related behavior was evaluated using the Conners Behavior Rating Scales in adolescence. We used multivariable linear regression models to quantify associations between Mn in each exposure period, and multiple informant models to compare associations across exposure periods.

Results

Median tooth Mn levels (normalized to calcium) were 0.4 area under the curve (AUC) 55Mn:43Ca × 104, 0.1 AUC 55Mn:43Ca × 104, and 0.0006 55Mn:43Ca for the prenatal, postnatal, and childhood periods. A doubling in prenatal tooth Mn levels was associated with 5.3% (95% confidence intervals [CI] = -10.3%, 0.0%) lower (i.e., better) teacher-reported inattention scores, whereas a doubling in postnatal tooth Mn levels was associated with 4.5% (95% CI = -9.3%, 0.6%) and 4.6% (95% CI = -9.5%, 0.6%) lower parent-reported inattention and attention deficit/hyperactivity disorder index scores, respectively. Childhood Mn was not beneficially associated with reported attention-related behaviors.

Conclusion

Protective associations in the prenatal and postnatal periods suggest Mn is beneficial for attention-related behavior, but not in the childhood period.

Probucol neuroprotection against manganese-induced damage in adult Wistar rat brain slices

Manganese (Mn) is an abundant element used for commercial purposes and is essential for the proper function of biological systems. Chronic exposure to high Mn concentrations causes Manganism, a Parkinson's-like neurological disorder. The pathophysiological mechanism of Manganism remains unknown; however, it involves mitochondrial dysfunction and oxidative stress. This study assessed the neuroprotective effect of probucol, a hypolipidemic agent with anti-inflammatory and antioxidant properties, on cell viability and oxidative stress in slices of the cerebral cortex and striatum from adult male Wistar rats. Brain structure slices were kept separately and incubated with manganese chloride (MnCl2) and probucol to evaluate the cell viability and oxidative parameters. Probucol prevented Mn toxicity in the cerebral cortex and striatum, as evidenced by the preservation of cell viability observed with probucol (10 and 30 μM) pre-treatment, as well as the prevention of mitochondrial complex I inhibition in the striatum (30 μM). These findings support the protective antioxidant action of probucol, attributed to its ability to prevent cell death and mitigate Mn-induced mitochondrial dysfunction.

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.

Heavy metal deposition and parameter change of soft contact lenses by exposure to particulate matter : Parameter change of SCL due to exposure to PM and heavy metal deposition

BACKGROUND

Particulate matter (PM) is known to contain heavy metals and be harmful to the tissues and organs of the human body including the eyes. As such, in this study, the deposition of heavy metals from PM on soft contact lenses was examined, and changes in the lens parameters were further investigated.

METHODS

Six types of soft contact lenses were exposed to captured PM10 for eight hours. The central thickness, water content, refractive power, and oxygen transmissibility of each contact lens were measured after analyzing the amounts of six heavy metals adsorbed on the contact lenses.

RESULTS

Lead, manganese, barium, arsenic, vanadium, and cadmium were detected in the captured PM, and only lead was adsorbed on all soft contact lenses except senofilcon C. The largest deposition was 23.21 ± 0.70 (10- 3)µg/lens of the lead on lotrafilcon B. The oxygen transmissibility of nelfilcon A exhibited statistically significant changes, however, it was within the ISO standard tolerance. Nevertheless, changes in the central thickness, water content, and refractive power of each soft contact lens were not statistically significant.

CONCLUSIONS

This study revealed that a considerable amount of lead in PM10 was adsorbed on soft contact lenses. Amongst lens parameters, only oxygen transmissibility changed significantly. Thus, wearing soft contact lenses under high PM10 concentration might affect the physiology of the eyes.

Compositional variations in metal nanoparticle components of welding fumes impact lung epithelial cell toxicity

Welding fumes contain harmful metals and gas by-products associated with development of lung dysfunction, asthma, bronchitis, and lung cancer. Two prominent welding fume particulate metal components are nanosized iron (Fe) and manganese (Mn) which might induce oxidative stress and inflammation resulting in pulmonary injury. Welding fume toxicity may be dependent upon metal nanoparticle (NP) components. To examine toxicity of welding fume NP components, a system was constructed for controlled and continuous NP generation from commercial welding and customized electrodes with varying proportions of Fe and Mn. Aerosols generated consisted of nanosized particles and were compositionally consistent with each electrode. Human alveolar lung A459 epithelial cells were exposed to freshly generated metal NP mixtures at a target concentration of 100 µg/m3 for 6 hr and then harvested for assessment of cytotoxicity, generation of reactive oxygen species (ROS), and alterations in the expression of genes and proteins involved in metal regulation, inflammatory responses, and oxidative stress. Aerosol exposures decreased cell viability and induced increased ROS production. Assessment of gene expression demonstrated variable up-regulation in cellular mechanisms related to metal transport and storage, inflammation, and oxidative stress based upon aerosol composition. Specifically, interleukin-8 (IL-8) demonstrated the most robust changes in both transcriptional and protein levels after exposure. Interleukin-8 has been determined to serve as a primary cytokine mediating inflammatory responses induced by welding fume exposures in alveolar epithelial cells. Overall, this study demonstrated variations in cellular responses to metal NP mixtures suggesting compositional variations in NP content within welding fumes may influence inhalation toxicity.

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.

The Structure of Maneb, An Important Manganese-Containing Bis(dithiocarbamate) Fungicide

Maneb is a manganese(II)-containing fungicide with a multi-site effect and no resistance, therefore it is widely applied in many parts of the world. There is, however, mounting evidence for neurotoxic effects with Parkinson-like symptoms (manganism) related to usage of Maneb. Due to its insolubility in most solvents and its paramagnetism, structural elucidation is not trivial, and thus its exact molecular structure remains unknown. We report herein a synthesis procedure to prepare Maneb reproducibly in pure form and the use of various analytical techniques including X-ray diffraction, X-ray absorption spectroscopy and electron diffraction to determine the molecular structure of Maneb in the solid state and also in solution.

Hybrids of manganese oxide and lipid liquid crystalline nanoparticles (LLCNPs@MnO) as potential magnetic resonance imaging (MRI) contrast agents

Due to the health risks associated with the use of Gd-chelates and the promising effects of using nanoparticles as T1 contrast agents (CAs) for MRI, Mn-based nanoparticles are considered a highly competitive alternative. The use of hybrid constructs with paramagnetic functionality of Mn-based nanoparticles is an effective approach, in particular, the use of biocompatible lipid liquid crystalline nanoparticles (LLCNPs) as a carrier of MnO nanoparticles. LLCNPs possess a unique internal structure ensuring a payload of different polarity MnO nanoparticles. In view of MRI application, the surface properties including the polarity of MnO are crucial factors determining their relaxation rate and thus the MRI efficiency. Two novel hybrid constructs consisting of LLCNPs loaded with hydrophobic MnO-oleate and hydrophilic MnO-DMSA NPs were prepared. These nanosystems were studied in terms of their physico-chemical properties, positive T1 contrast enhancement properties (in vitro and in vivo) and biological safety. LLCNPs@MnO-oleate and LLCNPs@MnO-DMSA hybrids exhibited a heterogeneous phase composition, however with differences in the inner periodic arrangement and structural parameters, as well as in the preferable localization of MnO NPs within the LLCNPs. Also, these hybrids differed in terms of particle size-related parameters and colloidal stability, which was found to be strongly dependent on the addition of differently functionalized MnO NPs. Embedding both types of MnO NPs into LLCNPs resulted in high relaxivity parameters, in comparison to bare MnO-DMSA NPs and also commercially developed CAs (e.g. Dotarem and Teslascan). Further biosafety studies revealed that cell internalization pathways were dependent on the prepared hybrid type, while viability, effects on the mitochondria membrane potential and cytoskeletal networks were rather related to the susceptibility of the particular cell line. The high relaxation rates achieved with the developed hybrid LLCNPs@MnO enable them to be possibly used as novel and biologically safe MRI T1-enhancing CAs in in vivo imaging.

Heavy Metal Concentrations of Beeswax (Apis mellifera L.) at Different Ages

Beeswax is a naturally occurring product that worker bees produce. Beeswax is used in a variety of industries and pharmaceuticals. Humans utilize it extensively in cosmetics, medicinal formulations, and food manufacturing. Beeswax is an essential component of advanced contemporary beekeeping. Beekeepers, in particular, utilize significant amounts of beeswax to make beeswax comb foundation. In its natural condition, beeswax is white, but it becomes yellow then dark in color when it comes into touch with honey and pollen. The ongoing use of wax comb in bee activities (such as brood rearing, storage honey and bee bread), combined with environmental factors such as heavy metal and pesticide residues, resulted in a black color. Because of heavy metals can accumulate in wax for decades, beeswax can be a helpful tool for gathering data on hazardous contaminants in the environment. Because of their lipid-based chemical composition, beeswax combs act as a sink for numerous ambient pollutants as well as poisons when in the hive. The current study aims to measure nine heavy metals and important elements, including iron (Fe), chromium (Cr), zinc (Zn), copper (Cu), nickel (Ni), manganese (Mn), lead (Pb), cadmium (Cd), and cobalt (Co) in beeswax collected in the Behaira governorate region of Egypt between 2018 and 2022. Sample collection was conducted each year in triplicate. The samples were analyzed using an atomic absorption spectrophotometer. The quantity of metals in beeswax at different ages differed significantly. Depending on the wax age, Fe has the highest concentration in the range of 2.068 to 5.041 ppm, while Cd has the lowest ratio at 0.024 to 0.054 ppm from the first to fifth years old of comb age. The findings showed that as beeswax combs aged, the concentration of heavy metals rose. According to the study, it should gradually recycle beeswax combs each year and also adding new foundations.

Fenugreek seed powder protects mice against arsenic-induced neurobehavioral changes

The current study was designed to evaluate the protective effect of fenugreek seed powder against As-induced neurobehavioral and biochemical perturbations using a mouse model. Mice exposed to arsenic at 10 mg/kg body weight showed development of anxiety-like behavior and memory impairment compared to control mice in elevated plus maze and Morris water maze tests, respectively. A significantly decreased acetyl and butyrylcholinesterase, superoxide dismutase and glutathione reductase activities and brain-derived neurotrophic factor levels were found in the brain of arsenic-exposed mice compared to control mice. Interestingly, supplementation of fenugreek seed powder to arsenic-treated mice significantly restored the activity of cholinesterase and antioxidant enzymes (e.g. superoxide dismutase, glutathione reductase) as well as brain-derived neurotrophic factor levels in the brain tissue of arsenic-exposed mice. Consequently, reduced anxiety-like behavior, improved learning and memory were observed in fenugreek supplemented arsenic treated mice compared to only arsenic-exposed mice group. Thus, this study suggests that fenugreek seed powder reduces arsenic-induced neurotoxicity in mice.

Impact of Manganese and Chromate on Specific DNA Double-Strand Break Repair Pathways

Manganese is an essential trace element; nevertheless, on conditions of overload, it becomes toxic, with neurotoxicity being the main concern. Chromate is a well-known human carcinogen. The underlying mechanisms seem to be oxidative stress as well as direct DNA damage in the case of chromate, but also interactions with DNA repair systems in both cases. However, the impact of manganese and chromate on DNA double-strand break (DSB) repair pathways is largely unknown. In the present study, we examined the induction of DSB as well as the effect on specific DNA DSB repair mechanisms, namely homologous recombination (HR), non-homologous end joining (NHEJ), single strand annealing (SSA), and microhomology-mediated end joining (MMEJ). We applied DSB repair pathway-specific reporter cell lines, pulsed field gel electrophoresis as well as gene expression analysis, and investigated the binding of specific DNA repair proteins via immunoflourescence. While manganese did not seem to induce DNA DSB and had no impact on NHEJ and MMEJ, HR and SSA were inhibited. In the case of chromate, the induction of DSB was further supported. Regarding DSB repair, no inhibition was seen in the case of NHEJ and SSA, but HR was diminished and MMEJ was activated in a pronounced manner. The results indicate a specific inhibition of error-free HR by manganese and chromate, with a shift towards error-prone DSB repair mechanisms in both cases. These observations suggest the induction of genomic instability and may explain the microsatellite instability involved in chromate-induced carcinogenicity.

Nanoformulations targeting immune cells for cancer therapy: mRNA therapeutics

The approved worldwide use of two messenger RNA (mRNA) vaccines (BNT162b2 and mRNA-1273) in late 2020 has proven the remarkable success of mRNA therapeutics together with lipid nanoformulation technology in protecting people against coronaviruses during COVID-19 pandemic. This unprecedented and exciting dual strategy with nanoformulations and mRNA therapeutics in play is believed to be a promising paradigm in targeted cancer immunotherapy in future. Recent advances in nanoformulation technologies play a prominent role in adapting mRNA platform in cancer treatment. In this review, we introduce the biologic principles and advancements of mRNA technology, and chemistry fundamentals of intriguing mRNA delivery nanoformulations. We discuss the latest promising nano-mRNA therapeutics for enhanced cancer immunotherapy by modulation of targeted specific subtypes of immune cells, such as dendritic cells (DCs) at peripheral lymphoid organs for initiating mRNA cancer vaccine-mediated antigen specific immunotherapy, and DCs, natural killer (NK) cells, cytotoxic T cells, or multiple immunosuppressive immune cells at tumor microenvironment (TME) for reversing immune evasion. We highlight the clinical progress of advanced nano-mRNA therapeutics in targeted cancer therapy and provide our perspectives on future directions of this transformative integrated technology toward clinical implementation.

Nanovaccines Fostering Tertiary Lymphoid Structure to Attack Mimicry Nasopharyngeal Carcinoma

Tertiary lymphoid structures (TLSs) are formed in inflamed tissues, and recent studies demonstrated that the appearance of TLSs in tumor sites is associated with a good prognosis for tumor patients. However, the process of natural TLSs' formation was slow and uncontrollable. Herein, we developed a nanovaccine consisting of Epstein-Barr virus nuclear antigen 1 (EBNA1) and a bi-adjuvant of Mn²⁺ and cytosine-phosphate-guanine (CpG) formulated with tannic acid that significantly inhibited the development of mimicry nasopharyngeal carcinoma by fostering TLS formation. The nanovaccine activated LT-α and LT-β pathways, subsequently enhancing the expression of downstream chemokines, CCL19/CCL21, CXCL10 and CXCL13, in the tumor microenvironment. In turn, normalized blood and lymph vessels were detected in the tumor tissues of the nanovaccine group, correlated with increased infiltration of lymphocytes. Especially, the proportion of the B220⁺ CD8⁺ T, which was produced via trogocytosis between T and B cells during activation of T cells, was increased in tumors of the nanovaccine group. Furthermore, the intratumoral effector memory T cells (Tem), CD45⁺, CD3⁺, CD8⁺, CD44⁺, and CD62L^-, did not decrease after blocking the egress of T cells from tumor-draining lymph nodes by FTY-720. These results demonstrated that the nanovaccine can foster TLS formation, which thus enhances local immune responses significantly, delays tumor outgrowth, and prolongs the median survival time of murine models of mimicry nasopharyngeal carcinoma, demonstrating a promising strategy for nanovaccine development.

Dietary Trace Elements and the Pathogenesis of Neurodegenerative Diseases

Trace elements such as iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) are absorbed from food via the gastrointestinal tract, transported into the brain, and play central roles in normal brain functions. An excess of these trace elements often produces reactive oxygen species and damages the brain. Moreover, increasing evidence suggests that the dyshomeostasis of these metals is involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, prion diseases, and Lewy body diseases. The disease-related amyloidogenic proteins can regulate metal homeostasis at the synapses, and thus loss of the protective functions of these amyloidogenic proteins causes neurodegeneration. Meanwhile, metal-induced conformational changes of the amyloidogenic proteins contribute to enhancing their neurotoxicity. Moreover, excess Zn and Cu play central roles in the pathogenesis of vascular-type senile dementia. Here, we present an overview of the intake, absorption, and transport of four essential elements (Fe, Zn, Cu, Mn) and one non-essential element (aluminum: Al) in food and their connections with the pathogenesis of neurodegenerative diseases based on metal-protein, and metal-metal cross-talk.

The pollutome-connectome axis: a putative mechanism to explain pollution effects on neurodegeneration

The study of pollutant effects is extremely important to address the epochal challenges we are facing, where world populations are increasingly moving from rural to urban centers, revolutionizing our world into an urban world. These transformations will exacerbate pollution, thus highlighting the necessity to unravel its effect on human health. Epidemiological studies have reported that pollution increases the risk of neurological diseases, with growing evidence on the risk of neurodegenerative disorders. Air pollution and water pollutants are the main chemicals driving this risk. These chemicals can promote inflammation, acting in synergy with genotype vulnerability. However, the biological underpinnings of this association are unknown. In this review, we focus on the link between pollution and brain network connectivity at the macro-scale level. We provide an updated overview of epidemiological findings and studies investigating brain network changes associated with pollution exposure, and discuss the mechanistic insights of pollution-induced brain changes through neural networks. We explain, in detail, the pollutome-connectome axis that might provide the functional substrate for pollution-induced processes leading to cognitive impairment and neurodegeneration. We describe this model within the framework of two pollutants, air pollution, a widely recognized threat, and polyfluoroalkyl substances, a large class of synthetic chemicals which are currently emerging as new neurotoxic source.

Clerodendrum viscosum leaves attenuate lead-induced neurotoxicity through upregulation of BDNF-Akt-Nrf2 pathway in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Clerodendrum viscosum is an important medicinal plant in Ayurveda in Bangladesh and its leaves are used as a remedy for various diseases such as anti-inflammatory, antibacterial, hyperglycemic, hepatoprotective effects.

AIM OF THE STUDY

The present study aimed to evaluate the protective effect of aqueous extract of C. viscosum leaves against Pb-induced neurobehavioral and biochemical changes in mice.

MATERIALS AND METHODS

Swiss albino mice were divided as a) control, b) lead treated (Pb) and c) C. viscosum leaves (Cle) d) Pb plus Cle groups. Pb-acetate (10 mg/kg body weight) was given to Pb and Pb + Cle groups mice, and water extract of leaves (50 mg/kg body weight) was provided as supplementation to Cle and Pb + Cle groups mice for 30 days. Elevated plus maze and Morris water maze tests were used for evaluating anxiety, spatial memory and learning, respectively. Status of cholinesterase, SOD, GSH enzyme activity and neurotoxicity markers such BDNF and Nrf2 levels were analyzed in the brain tissue of experimental mice.

RESULTS

Poorer learning, inferior spatial memory, and increased anxiety-like behavior in Pb-exposure mice were noted when compared to control mice in Morris water maze and elevated plus maze test, respectively. In addition, expression of BDNF and Nrf2, cholinesterase activity along with antioxidant activity were significantly reduced compared to control group (p < 0.01). Interestingly, C. viscosum leaves' aqueous extract supplementation in Pb-exposed mice provide a significant improved neurochemical and antioxidant properties through the augmentation of activity of cholinergic enzymes, and upregulation of BDNF and Nrf2 levels in the brain tissue compared to Pb-exposed mice.

CONCLUSIONS

This study suggested that C. viscosum leaves restore the cognitive dysfunction and reduce anxiety-like behavior through upregulation of BDNF mediated Akt-Nrf2 pathway in Pb-exposure mice.

Evaluating Water bitter leaf (Struchium sparganophora) and Scent Leaf (Ocimum gratissimum) extracts as sources of nutraceuticals against manganese-induced toxicity in fruit fly model

Tropical vegetables remain one of the major sources of functional foods and nutraceuticals, while their constituent phytochemicals, especially alkaloids, have been reported to exhibit neuroprotective properties. Here, the protective effect of alkaloid extracts from Scent leaf (Ocimum gratissimum) and Water bitter leaf (Struchium sparganophora) on manganese (Mn)- induced toxicity in wild type fruit fly (Drosophila melanogaster) model was investigated. Flies were exposed to 30 mM of Mn, the alkaloid extracts (20 and 200 µg/g) and co-treatment of Mn plus extracts, respectively. The survival rate and locomotor performance of the flies were assessed 7 days post-treatment, after which the flies were homogenized and assayed for activities of acetylcholinesterase (AChE), monoamine oxidase (MAO), glutathione-S transferase (GST), catalase, superoxide dismutase SOD), as well as total thiol, reactive oxygen species (ROS) and neural L-DOPA levels. Results showed that the extract significantly reversed Mn-induced reduction in the survival rate and locomotor performance of the flies. Furthermore, both extracts counteracted the Mn-induced elevation in AChE and MAO activities, as well as reduced antioxidant enzyme activities, with a concomitant mitigation of Mn-induced elevated ROS and neural L-DOPA level. The HPLC characterization of the extracts revealed the presence of N-propylamine, Vernomine and Piperidine as predominant in Water bitter leaf extract, while 2, 6-dimethylpyrazine and sesbanimide were found in scent leaf extract. Therefore, the alkaloid extract of these leaves may thus be sources of useful nutraceuticals for the management of pathological conditions associated with manganese toxicity.

Goose Meat as a Source of Dietary Manganese-A Systematic Review

Manganese is a trace element with essential physiological functions that should be supplied to animals and humans through diet. Goose meat is prevalent in many regions of the world. Therefore, the aim of the study was a systematic review (PRISMA statement, 1980-2022) of the content of Mn in raw and cooked goose meat and their relation to the recommended intake at the level of adequate intake (AI) and the nutrient reference values-requirements (NRV-R). The literature analysis shows that the content of Mn in goose meat depends on the breed, type of muscles, the presence of skin, and the cooking method used. AI level recommendations for Mn intake range from 0.003 to 5.50 mg/day, depending on the country, age, and gender. Consumption by adults (regardless of sex) of 100 g of domestic or wild goose meat covers the daily AI per Mn in various percentages, depending on the type of muscles (more Mn in leg muscles), presence of skin (more Mn in skinless muscles), and thermal treatment (pan fried with oil, grilled, and cooked meat contains more). Placing information on the Mn content in goose meat and the percentage of NRV-R on the packaging may be valuable information for the consumer in making food choices to diversify the diet. There are few studies on the content of Mn in goose meat. Therefore, it is reasonable to conduct research in this area.

Essential Trace Elements Prevent the Impairment in the Retention Memory, Cerebral Cortex, and Cerebellum Damage in Male Rats Exposed to Quaternary Metal Mixture by Up-regulation, of Heme Oxygynase-1 and Down-regulation of Nuclear Factor Erythroid 2-related Factor 2-NOs Signaling Pathways

In the present study, we examined adverse effects of metals and metalloids in the Cerebral cortex (CC) and Cerebellum (CE). Group 1 comprised from the controls while other four groups of male Wistar rats were treated with following pattern: Group II (Heavy Metal Mixture HMM only: PbCl₂, 20 mg·kg^-1; CdCl₂, 1.61 mg·kg^-1; HgCl₂, 0.40 mg·kg^-1, and NaAsO₃,10 mg·kg^-1), Groups III (HMM + ZnCl₂); Group IV (HMM + Na₂SeO₃) and Group V (HMM + ZnCl₂ + Na₂SeO₃) for 60 days per os. HMM promoted oxidative stress in the CC and CE of treated rats compared to controls; moreover, exposure to HMM led to increased activity of the AChE and pro-inflammatory cytokines; also, HMM promoted accumulation of caspase 3 and other transcriptional factors such as Nrf2 and decreased levels of Hmox-1. Essential metals reduced increased bioaccumulation of Pb, Cd, As and Hg in CC and CE caused by HMM exposure. Also, all mentioned adverse effects were diminished by essential metals treatment (Se and Zn). HMM exposed rats had considerably less escape dormancy than controls. Histopathological analysis revealed moderate cell loss at the intermediate (Purkinje cell) and granular layer. Zinc and selenium supplementations could reverse adverse effects of heavy metals at various cellular levels in neurons.

Sesamol alleviates manganese-induced neuroinflammation and cognitive impairment via regulating the microglial cGAS-STING/NF-κB pathway

Toxic effects of excessive manganese (Mn) from occupational or environmental exposure cause harm to human health. Excessive Mn exposure is intimately associated with neurodegeneration and cognitive dysfunction. Inflammatory responses mediated by microglia are essential contributors to the pathogenesis of Mn-induced neurotoxicity. Inhibition of microglia-mediated inflammation has been shown to alleviate Mn-induced neurotoxicity. Sesamol, derived from sesame, has neuroprotective properties in various disease models, including neurological diseases. Whether sesamol protects against Mn-induced neurological injuries has not been determined. Here, both in vivo and in vitro Mn exposure models were established to address the beneficial effects of sesamol on Mn-induced neurotoxicity. We showed that administration of sesamol mitigated learning and memory deficits of mice treated by Mn. Furthermore, sesamol reduced Mn-induced microglial activation and the expression of proinflammatory mediators (TNF-α, iNOS, and Cxcl10), while exerting a marginal effect on anti-inflammation and microglial phagocytosis. Mn exposure activated the microglial cGAS-STING pathway and sesamol inhibited this pathway by reducing the phosphorylation of STING and NF-κB, concomitantly decreasing IFN-α and IFN-β synthesis. In summary, our novel results indicated that sesamol exerted its protective effects on Mn-induced neuroinflammation and cognitive impairment via the microglial cGAS-STING/NF-κB pathway, providing evidence that sesamol may serve as an effective therapeutic for preventing and treating Mn-induced neurotoxicity.

pH-Sensitive and Biodegradable Mn3(PO4)2·3H2O Nanoparticles as an Adjuvant of Protein-Based Bivalent COVID-19 Vaccine to Induce Potent and Broad-Spectrum Immunity

Developing a novel and potent adjuvant with great biocompatibility for immune response augmentation is of great significance to enhance vaccine efficacy. In this work, we prepared a long-term stable, pH-sensitive, and biodegradable Mn3(PO4)2·3H2O nanoparticle (nano-MnP) by simply mixing MnCl2/NaH2PO4/Na2HPO4 solution for the first time and employed it as an immune stimulant in the bivalent COVID-19 protein vaccine comprised of wild-type S1 (S1-WT) and Omicron S1 (S1-Omicron) proteins as antigens to elicit a broad-spectrum immunity. The biological experiments indicated that the nano-MnP could effectively activate antigen-presenting cells through the cGAS-STING pathway. Compared with the conventional Alum-adjuvanted group, the nano-MnP-adjuvanted bivalent vaccine elicited approximately 7- and 8-fold increases in IgG antibody titers and antigen-specific IFN-γ secreting T cells, respectively. Importantly, antisera of the nano-MnP-adjuvanted group could effectively cross-neutralize the SARS-CoV-2 and its five variants of concern (VOCs) including Alpha, Beta, Gamma, Delta, and Omicron, demonstrating that this bivalent vaccine based on S1-WT and S1-Omicron proteins is an effective vaccine design strategy to induce broad-spectrum immune responses. Collectively, this nano-MnP material may provide a novel and efficient adjuvant platform for various prophylactic and therapeutic vaccines and provide insights for the development of the next-generation manganese adjuvant.

Drinking Water From Private Wells and Risks to Children

Drinking water for approximately 23 million US households is obtained from private wells. These wells can become contaminated by pollutant chemicals or pathogenic organisms, leading to significant illness. Although the US Environmental Protection Agency and all states offer guidance for construction, maintenance, and testing of private wells, most states only regulate the construction of new private water wells. With a few exceptions, there is little regulation after construction. Well owners are responsible for their own wells. Children may also drink well water at child care or when traveling. Illness resulting from children’s ingestion of contaminated water can be severe. This report reviews relevant aspects of groundwater and wells; describes the common chemical and microbiologic contaminants; gives an algorithm with recommendations for inspection, testing, and remediation for wells providing drinking water for children; and provides references and Internet resources for more information.

Recent progress toward understanding the role of ZIP14 in regulating systemic manganese homeostasis

ZIP14 is a metal transporter essential for the regulation of body manganese homeostasis. The physiological functions of ZIP14 have been uncovered mainly through two lines of in vivo studies that examined the phenotypes of ZIP14 loss, including studies of humans with ZIP14 mutations and animals with ZIP14 deficiency. This mini review aims at presenting an updated view of the important advances made towards understanding the genetic and pathological mechanisms of brain manganese overload caused by ZIP14 deficiency.

An Insight into the Molecular Mechanism of Mitochondrial Toxicant-induced Neuronal Apoptosis in Parkinson's Disease

Parkinson's disease (PD) is one of the most common progressive neurodegenerative disorders affecting approximately 1% of the world's population at the age of 50 and above. Majority of PD cases are sporadic and show symptoms after the age of 60 and above. At that time, most of the dopaminergic neurons in the region of substantia nigra pars compacta have been degenerated. Although in past decades, discoveries of genetic mutations linked to PD have significantly impacted our current understanding of the pathogenesis of this devastating disorder, it is likely that the environment also plays a critical role in the etiology of sporadic PD. Recent epidemiological and experimental studies indicate that exposure to environmental agents, including a number of agricultural and industrial chemicals, may contribute to the pathogenesis of several neurodegenerative disorders, including PD. Furthermore, there is a strong correlation between mitochondrial dysfunction and several forms of neurodegenerative disorders, including Alzheimer's disease (AD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS) and PD. Interestingly, substantia nigra of patients with PD has been shown to have a mild deficiency in mitochondrial respiratory electron transport chain NADH dehydrogenase (Complex I) activity. This review discusses the role of mitochondrial toxicants in the selective degeneration of dopaminergic neurons targeting the electron transport system that leads to Parkinsonism.

Association Between the Ratios of Selenium to Several Elements and Mild Cognitive Impairment in the Elderly

To investigate the relationship between the correlation ratios of selenium (Se) and other elements and mild cognitive impairment (MCI) among older adults. A total of 1000 individuals participated in our research analysis. The concentrations of elements in whole blood were determined using inductively coupled plasma mass spectrometry to reflect their exposure levels. Participants' cognitive function was assessed using the Mini-Mental State Examination. Logistic regression analysis was used to evaluate the relationship between elemental ratios and MCI. Se concentration was positively correlated with red blood cell count (r = 0.219, p < 0.001), haemoglobin level (r = 0.355, p < 0.001), haematocrit (r = 0.215, p < 0.001), mean corpuscular haemoglobin (r = 0.294, p < 0.001) and mean corpuscular haemoglobin concentration (r = 0.428, p < 0.001) and negatively correlated with red cell volume distribution width-standard deviation (r = -0.232, p < 0.001) and platelet distribution width (r = -0.382, p < 0.001). Compared with the normal group, the ratios of Se/vanadium (V), Se/lead (Pb) and Se/cadmium (Cd) in the whole blood of the MCI group were significantly lower (all p < 0.001), while the ratios of manganese (Mn)/Se and iron (Fe)/Se were higher (all p < 0.001). The increase in the ratios of Se/V, Se/Pb and Se/Cd is related to a decreased risk of MCI among older adults; contrarily, an increase in the ratios of Mn/Se and Fe/Se may be a risk factor for MCI.

Comparative toxicological assessment of three soils polluted with different levels of hydrocarbons and heavy metals using in vitro and in vivo approaches

The biological effects induced by the pollutants present in soils, together with the chemical and physical characterizations, are good indicators to provide a general overview of their quality. However, the existence of studies where the toxicity associated to soils contaminated with mixtures of pollutants applying both in vitro and in vivo models are scarce. In this work, three soils (namely, Soil 001, Soil 002 and Soil 013) polluted with different concentrations of hydrocarbons and heavy metals were evaluated using different organisms representative of human (HepG2 human cell line) and environmental exposure (the yeast Saccharomyces cerevisiae, the Gram-negative bacterium Pseudomonas putida and, for the in vivo evaluation, the annelid Enchytraeus crypticus). In vitro assays showed that the soluble fraction of the Soil 001, which presented the highest levels of heavy metals, represented a great impact in the viability of the HepG2 cells and S. cerevisiae, while organic extracts from Soils 002 and 013 caused a slight decrease in the viability of HepG2 cells. In addition, in vivo experiments showed that Soils 001 and 013 affected the survival and the reproduction of E. crypticus. Altogether, these results provide a general overview of the potential hazards associated to three specific contaminated sites in a variety of organisms, showing how different concentrations of similar pollutants affect them, and highlights the relevance of testing both organic and soluble extracts when in vitro safety assays of soils are performed.

Manganese Stress Tolerance Depends on Yap1 and Stress-Activated MAP Kinases

Understanding which intracellular signaling pathways are activated by manganese stress is crucial to decipher how metal overload compromise cellular integrity. Here, we unveil a role for oxidative and cell wall stress signaling in the response to manganese stress in yeast. We find that the oxidative stress transcription factor Yap1 protects cells against manganese toxicity. Conversely, extracellular manganese addition causes a rapid decay in Yap1 protein levels. In addition, manganese stress activates the MAPKs Hog1 and Slt2 (Mpk1) and leads to an up-regulation of the Slt2 downstream transcription factor target Rlm1. Importantly, Yap1 and Slt2 are both required to protect cells from oxidative stress in mutants impaired in manganese detoxification. Under such circumstances, Slt2 activation is enhanced upon Yap1 depletion suggesting an interplay between different stress signaling nodes to optimize cellular stress responses and manganese tolerance.

A Longitudinal Study of Exposure to Manganese and Incidence of Metabolic Syndrome

The association between manganese (Mn) and metabolic syndrome (MetS) is unclear, and no prior study has studied this association longitudinally. The aim of this study was to assess longitudinal associations of Mn exposure with MetS and metabolic outcomes. We used data from the San Luis Valley Diabetes Study (SLVDS), a prospective cohort from rural Colorado with data collected from 1984−1998 (n = 1478). Urinary Mn was measured at baseline (range = 0.20−42.5 µg/L). We assessed the shape of the cross-sectional association between Mn and MetS accounting for effect modification by other metals at baseline using Bayesian kernel machine regression. We assessed longitudinal associations between baseline quartiles of Mn and incident MetS using Fine and Gray competing risks regression models (competing risk = mortality) and between quartiles of Mn and metabolic outcomes using linear mixed effects models. We did not observe evidence that quartiles of Mn were associated with incident MetS (p-value for trend = 0.52). Quartiles of Mn were significantly associated with lower fasting glucose (p-value for trend < 0.01). Lead was found to be a possible effect modifier of the association between Mn and incident MetS. Mn was associated with lower fasting glucose in this rural population. Our results support a possible beneficial effect of Mn on diabetic markers.

An Overview of Essential Microelements and Common Metallic Nanoparticles and Their Effects on Male Fertility

Numerous factors affect reproduction, including stress, diet, obesity, the use of stimulants, or exposure to toxins, along with heavy elements (lead, silver, cadmium, uranium, vanadium, mercury, arsenic). Metals, like other xenotoxins, can cause infertility through, e.g., impairment of endocrine function and gametogenesis or excess production of reactive oxygen species (ROS). The advancement of nanotechnology has created another hazard to human safety through exposure to metals in the form of nanomaterials (NMs). Nanoparticles (NPs) exhibit a specific ability to penetrate cell membranes and biological barriers in the human body. These ultra-fine particles (<100 nm) can enter the human body through the respiratory tract, food, skin, injection, or implantation. Once absorbed, NPs are transported to various organs through the blood or lymph. Absorbed NPs, thanks to ultrahigh reactivity compared to bulk materials in microscale size, disrupt the homeostasis of the body as a result of interaction with biological molecules such as DNA, lipids, and proteins; interfering with the functioning of cells, organs, and physiological systems; and leading to severe pathological dysfunctions. Over the past decades, much research has been performed on the reproductive effects of essential trace elements. The research hypothesis that disturbances in the metabolism of trace elements are one of the many causes of infertility has been unquestionably confirmed. This review examines the complex reproductive risks for men regarding the exposure to potentially harmless xenobiotics based on a series of 298 articles over the past 30 years. The research was conducted using PubMed, Web of Science, and Scopus databases searching for papers devoted to in vivo and in vitro studies related to the influence of essential elements (iron, selenium, manganese, cobalt, zinc, copper, and molybdenum) and widely used metallic NPs on male reproduction potential.