Manganese Toxicity Upon Overexposure: a Decade in Review

Engineering mesoporous polydopamine-based potentiate STING pathway activation for advanced anti-biofilm therapy

The biofilm-induced "relatively immune-compromised zone" creates an immunosuppressive microenvironment that is a significant contributor to refractory infections in orthopedic endophytes. Consequently, the manipulation of immune cells to co-inhibit or co-activate signaling represents a crucial strategy for the management of biofilm. This study reports the incorporation of Mn2+ into mesoporous dopamine nanoparticles (Mnp) containing the stimulator of interferon genes (STING) pathway activator cGAMP (Mncp), and outer wrapping by M1-like macrophage cell membrane (m-Mncp). The cell membrane enhances the material's targeting ability for biofilm, allowing it to accumulate locally at the infectious focus. Furthermore, m-Mncp mechanically disrupts the biofilm through photothermal therapy and induces antigen exposure through photodynamic therapy-generated reactive oxygen species (ROS). Importantly, the modulation of immunosuppression and immune activation results in the augmentation of antigen-presenting cells (APCs) and the commencement of antigen presentation, thereby inducing biofilm-specific humoral immunity and memory responses. Additionally, this approach effectively suppresses the activation of myeloid-derived suppressor cells (MDSCs) while simultaneously boosting the activity of T cells. Our study showcases the efficacy of utilizing m-Mncp immunotherapy in conjunction with photothermal and photodynamic therapy to effectively mitigate residual and recurrent infections following the extraction of infected implants. As such, this research presents a viable alternative to traditional antibiotic treatments for biofilm that are challenging to manage.

Exposure to Multiple Metal(loid)s and Hypertension in Chinese Older Adults

Evidence about effects of metal(loid)s on hypertension among adults is insufficient. The aim of our study was to evaluate the individual and joint associations between seven selected metal(loid)s and hypertension, including lead (Pb), manganese (Mn), nickel (Ni), arsenic (As), cadmium (Cd), chromium (Cr), and vanadium (V)) in Chinese older adults. This study included 1009 older adults, and the blood concentrations of seven metal(loid)s were evaluated by inductively coupled plasma mass spectrometry (ICP-MS). The following conditions were considered as hypertension: (1) either systolic blood pressure ≥ 140 mm Hg or diastolic blood pressure ≥ 90 mm Hg, (2) a self-reported history of hypertension, or (3) currently taking antihypertensive medications. Logistic regression was utilized to investigate the association between individual metal(loid) and hypertension, while Bayesian kernel machine regression (BKMR) was employed to investigate the association of the metal(loid) mixture with hypertension. Adjusted single-metal(loid) model showed a significant positive association between Pb and hypertension (OR = 1.24, 95%CI = 1.03-1.50). This significant association still existed in multi-metal(loid) model (OR = 1.22, 95%CI = 1.01-1.47). BKMR further indicated a positive linear association of Pb with hypertension. The metal(loid) mixture was positively associated with hypertension in older adults, although not significant. Within the mixture, Pb had the highest posterior inclusion probabilities value (PIP = 0.9192). There were multiplicative interactions of Pb and Mn on hypertension. In addition, Pb and Mn had additive effects on the association of other blood metal(loid)s with hypertension. The associations of multiple metal(loid)s with hypertension are dependent on diabetes, areas, age, and BMI. The metal(loid) mixture exposure may contribute to hypertension in Chinese older adults, mainly driven by Pb and interactions of Pb and Mn. Reducing exposure to these metal(loid)s may prevent hypertension among older adults, which is especially true for those living with diabetes.

Welding techniques and manganese concentrations in blood and brain: Results from the WELDFUMES study

This study used whole-brain mapping to investigate the effect of different welding processes on manganese (Mn) accumulation in the brain. Exposure measurements were performed at the welders' workplaces about 3 weeks before a magnetic resonance imaging (MRI) examination. The welders were categorized into three main groups based on welding method, and the T1-relaxation rate (R1) was measured using quantitative MRI (qMRI). Welders using shielded metal arc welding (SMAW) were found to have lower accumulations of total Mn in clusters encompassing white matter, thalamus, putamen, pallidum, and substantia nigra compared with welders using inert gas tungsten arc welding (GTAW) or continuous consumable electrode arc welding (CCEAW). A positive correlation was found between Mn in red blood cells (Mn-RBC) and R1 in a region encompassing pre-and post-central gyri. The results of this study show that the accumulation of free, bound, or compartmentalized Mn ions in the brain differed depending on the welding method used. These differences were predominately located in the basal ganglia but were also found in regions encompassing white matter. The level of Mn-RBC was correlated to the deposition of Mn in the left primary somatosensory and motor cortex and may therefore be linked to neurological and neurobehavioral symptoms.

A Comparative Study to Explore the Variability of Heavy Metal Concentration in the Teeth of Residents of Non-gated Versus Gated Societies

Human populations face increasing exposure to heavy metals, which pose significant health risks. Dental tissues, such as dentin and enamel, provide a reliable biomarker for assessing long-term heavy metal exposure due to their stable nature. This study aims to explore the variability of heavy metal concentrations in the teeth dentine of residents living in gated versus non-gated societies near the Yamuna River around the Jamia Millia Islamia, New Delhi, India. Sixty-nine participants were enrolled, 27 from gated societies and 42 from non-gated societies. Participants underwent elective dental extraction, following which heavy metal concentrations were measured in extracted tooth dentine using atomic absorption spectrophotometry. Demographic data including age, gender, tooth types, and drinking water sources were recorded. Statistical analysis included Mann-Whitney's test, Spearman correlation heatmap, and principal component analysis (PCA). Residents of non-gated societies exhibited significantly (p < 0.005) higher mean concentrations of heavy metals compared to gated societies except for cadmium (p = 0.495). Subgroup analysis based on drinking water sources revealed significant (p < 0.001) variations in heavy metal concentrations, suggesting the influence of water quality on environmental exposure. PCA provided insights into underlying trends and correlations among heavy metal variables. This study provides valuable insights into heavy metal contamination among residents living near the Yamuna River, highlighting disparities in exposure based on residential environment and drinking water sources. Participants from non-gated societies exhibited higher mean concentrations of heavy metals compared to those from gated societies, emphasizing the influence of socio-economic factors, urban infrastructure and environmental management practices on heavy metal accumulation. The study's findings underscore the need for targeted interventions to address heavy metal exposure across diverse population groups, improve water quality standards, and enhance access to safe drinking water.

Biosorption of copper, nickel, and manganese as well as the production of metal nanoparticles by Bacillus species isolated from soils contaminated with electronic wastes

Improper electronic waste management in the world especially in developing countries such as Iran has resulted in environmental pollution. Copper, nickel, and manganese are from the most concerned soil contaminating heavy metals which found in many electronic devices that are not properly processed. The aim of this study was to investigate the biological removal of copper, nickel, and manganese by Bacillus species isolated from a landfill of electronic waste (Zainal Pass hills located in Isfahan, Iran) which is the and to produce nanoparticles from the studied metals by the isolated bacteria. The amounts of copper, nickel, and manganese in the soil was measured as 1.9 × 104 mg/kg, 0.011 × 104 mg/kg and 0.013 × 104 mg/kg, respectively based on ICP-OES analysis, which was significantly higher than normal (0.02 mg/kg, 0.05 mg/kg, and 2 mg/kg, respectively. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of metals on the bacterial isolates was determined. The biosorption of metals by the bacteria was evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES). The metal nanoparticles were synthetized utilizing the isolates in culture media containing the heavy metals with the concentrations to which the isolates had shown resistance. X ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used for the evaluation of the fabrication of the produced metal nanoparticles. Based on the findings of this study, a total of 15 bacterial isolates were obtained from the soil samples. The obtained MICs of copper, nickel, and manganese on the isolates were 40-300 mM, 4-10 mM, and 60-120 mM, respectively. The most resistant isolates to copper were FM1 and FM2 which were able to bio-remove 79.81% and 68.69% of the metal, respectively. FM4 and FM5 were respectively the most resistant isolate to nickel and manganese and were able to bio-remove 86.74% and 91.96% of the metals, respectively. FM1, FM2, FM4, and FM5 was molecularly identified as Bacillus cereus, Bacillus thuringiensis, Bacillus paramycoides, and Bacillus wiedmannii, respectively. The results of XRD, SEM and EDS showed conversion of the copper and manganese into spherical and oval nanoparticles with the approximate sizes of 20-40 nm. Due to the fact that the novel strains in this study showed high resistance to copper, nickel, and manganese and high adsorption of the metals, they can be used in the future, as suitable strains for the bio-removal of these metals from electronic and other industrial wastes.

Do toenail manganese and iron levels reflect brain metal levels or brain metabolism in welders?

Inhalation of welding fumes can cause metal accumulation in the brain, leading to Parkinsonian-like symptoms. Metal accumulation and altered neurochemical profiles have been observed using magnetic resonance imaging (MRI) in highly exposed welders, being associated with decreased motor function and cognition. While MRI is impractical to use as a health risk assessment tool in occupational settings, toenail metal levels are easier to assess and have been demonstrated to reflect an exposure window of 7-12 months in the past. Yet, it is unclear whether toenail metal levels are associated with brain metal levels or changes in metabolism, which are the root of potential health concerns. This study investigates whether toenail manganese (Mn) and iron (Fe) levels, assessed at several time points, correlate with brain Mn and Fe levels, measured by MRI, as well as brain GABA, glutamate (Glu), and glutathione (GSH) levels, measured by Magnetic Resonance Spectroscopy (MRS), in seventeen Mn-exposed welders. Quantitative T1 and R2* MRI maps of the whole brain, along with GABA, Glu, and GSH MRS measurements from the thalamus and cerebellum were acquired at baseline (T0). Toenail clippings were collected at T0 and every three months after the MRI for a year to account for different exposure periods being reflected by toenail clippings and MRI. Spearman correlations of toenail metal levels were run against brain metal and metabolite levels, but no significant associations were found for Mn at any timepoint. Cerebellar GSH positively correlated with toenail Fe clipped twelve months after the MRI (p = 0.05), suggesting an association with Fe exposure at the time of the MRI. Neither thalamic GABA nor Glu correlated with toenail Fe levels. In conclusion, this study cannot support toenail Mn as a proxy for brain Mn levels or metabolic changes, while toenail Fe appears linked to brain metabolic alterations, underscoring the importance of considering other metals, including Fe, in studying Mn neurotoxicity.

Presence of micronuclei and nuclear abnormalities in Caracara (Polyborus) plancus living in an airport area in southern Brazil

The aviation sector is believed to be responsible for considerable environmental damage attributed to emission of a large number and amount of pollutants. Airports are often surrounded by forest fragments and humid areas that attract birds of prey and hence may potentially serve as useful bioindicators. The aim of the present study was to examine genotoxic potential in raptors exposed to airport pollution using the micronucleus (MN) test and morphological changes as evidenced by bilateral symmetry. This investigation was conducted at Salgado Filho International Airport of Porto Alegre - RS as well as in private and zoological breeding grounds. The presence of metals was measured in the blood cells of the collected birds. Seventeen birds (Caracara (Polyborus) plancus) were used in this study 11 from exposed and 6 from non-exposed group. The nuclear alterations clearly indicate that organisms exposed to airport pollution exhibited a significantly higher frequency of genetic damage compared to non-exposed birds. Further, manganese and chromium were detected exclusively in the blood of the exposed group. In contrast, the analysis of bilateral symmetry did not detect any significant morphologic differences between the two groups. Therefore, data indicate that blood genotoxic stress occurs in birds of prey living in civil aviation areas as evidenced by MN frequency increase and presence of manganese and chromium.

The association of manganese levels with red cell distribution width: A population-based study

OBJECTIVES

Experimental and acute exposure studies imply that manganese affects red blood cell production. Nevertheless, the association between environmental exposure and red blood cell distribution width (RDW) has yet to be explored. This research sought to assess the correlation between blood manganese levels and RDW within the general population of the United States.

MATERIALS AND METHODS

Employing weighted multiple linear regression models, data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) were utilized to assess the correlation between manganese levels in the blood and RDW. Restricted cubic spline plots and two-piecewise linear regression models were also employed.

RESULT

The analysis included a total of 15882 participants in which we determined an independent positive relationship between blood manganese levels and RDW among participants(β = 0.079, P<0.001). Moreover, we identified a J-shaped association between blood manganese levels and RDW in total participants (inflection point for blood manganese: 7.32 ug/L) and distinct subgroups following adjusted covariates. Women exhibited a more pronounced association, even after controlling for adjusted covariates.

CONCLUSIONS

We determined a J-shaped relationship between blood manganese levels and RDW with an inflection point at 7.32 ug/L for blood manganese. Nevertheless, fundamental research and large sample prospective studies are needed to determine the extent to which blood manganese levels correlate with RDW.

Pronounced declines in heavy metal burdens of Minnesotan mammals over the last century

Humans have drastically altered the ecology of heavy metals, which can have negative effects on animal development and neural functioning. Many species have shown the ability to adapt to anthropogenic increases in metal pollution, but such evolutionary responses will depend on the extent of metal variation over space and time. For terrestrial vertebrates, it is unclear how metal exposure has changed over time: some studies suggest metal content peaked with the enactment of policies controlling lead emissions, while other studies suggest metal levels peaked at least a century earlier. We used 162 specimens of four mammal species (a mouse, shrew, bat, and squirrel) to ask how metal content of the fur and skin has changed over a 90-year time period, and impacts on individual performance (body size and cranial capacity). Using ICP-MS, we show that for lead, cadmium, copper, and chromium, there were significant declines in metal content in mammal tissue over the 90-year time period, with lead levels five times lower now than in the early 1900s. Importantly, metal content began to drop well before the pollution regulation of the 1970s. Effects of time greatly outweighed any effects of an individual living near a human population center. Surprisingly, there were no effects of body metal content on body size, and only manganese was negatively related to relative cranial capacity. Taken together, these results suggest that present day populations of mammals are experiencing levels of heavy metal exposure that are less stressful than they were 100 years ago. In addition, temporal decreases in metal loads likely partly reflect global patterns of pollution decline that affect atmospheric metal deposition rather than local point sources of exposure.

Sex-specific associations of a ferroalloy metal mixture with motor function in Italian adolescents

Background

Motor function is critical for children's health, yet remains an understudied neurodevelopmental domain. Exposure to metals has been linked with motor function, but no study has examined the joint effects of metal mixtures.

Methods

We evaluated cross-sectional associations between a metal mixture and motor function among 569 adolescents (10-14 years old) living near the ferroalloy industry. Concentrations of blood lead, hair manganese, hair copper, and hair chromium were quantified using inductively coupled plasma mass spectrometry. Neuropsychologists administered multiple fine motor function assessments: pursuit aiming, finger tapping, visual reaction time (VRT), and subtests from the Luria Nebraska battery. We estimated associations between motor function and the metal mixture using quantile-based g-computation and multivariable linear regression, adjusting for child age, sex, and socioeconomic status. We explored sex-specific associations in stratified models.

Results

Associations between the metal mixture and motor function were mostly null but were modified by sex. We observed a beneficial association among females: a quartile increase in all metals in the mixture was associated with a 2.6% faster average response time on the VRT (95% confidence interval [CI] = -4.7%, -0.5%), driven by Cu and Cr. In contrast, this association was adverse among males (ß = 1.5% slower response time [95% CI = -0.7%, 3.9%]), driven by Cu and Mn.

Conclusions

Results suggest that males may be more susceptible to the adverse effects of metal exposure on motor function during adolescence than females. Future studies, particularly prospective study designs, are warranted to further understand the associations of metal mixtures with motor function.

Frequencies of chromosomal aberrations and related biochemical parameters in welders

Stainless steel welders are exposed to heavy filler metals. We evaluated the concentration of these metals in whole blood and urine, and the relevant biochemical parameters in relation to the total chromosomal aberrations (CAs), chromatid-type (CTA-type, CTAs) and chromosome-type (CSA-type, CSAs), in 117 welders and control individuals. Statistically higher concentrations of the total Cr, Ni and Mn were observed in whole blood and urine of welders, and the concentrations were higher in welders who smoked. On the contrary, concentrations of urinary heavy metals Cr and Mn adjusted for creatinine were significantly higher in the control groups. A statistically higher frequency of total CAs was observed in the whole group of welders, and also in the non-smoking welders, as compared to controls. The frequency of total CAs significantly correlated with the concentration of Cr, Ni and Mn in whole blood (R=0.61, P˂0.0001, R=0.33, P˂0.0001 and R=0.66, P˂0.0001, respectively), with urinary concentrations of Ni and Mn (R=0.27, P=0.003 and R=0.28, P=0.003, respectively) and with urinary concentrations of Cr, Ni and Mn adjusted for creatinine (R=0.22, P=0.029, R=0.26, P=0.005 and R=0.20, P=0.030, respectively). Likewise, the frequency of CTA-types significantly correlated with the concentration of Cr and Mn in whole blood (R=0.31, P=0.0007 and R=0.34, P=0.0002). The frequency of CSA-types significantly correlated with concentrations of Cr, Ni and Mn in whole blood (R=0.43, P˂0.0001, R=0.38, P˂0.0001 and R=0.46, P˂0.0001, respectively). The statistically higher values of serum creatinine and total bilirubin were detected in all welders, as well as in smokers when compared to the corresponding controls. The exposure to heavy metals in welders increased the frequencies of CAs and altered the balance between urinary excretion of heavy metals and their possible accumulation.

Metabolic Derangement of Essential Transition Metals and Potential Antioxidant Therapies

Essential transition metals have key roles in oxygen transport, neurotransmitter synthesis, nucleic acid repair, cellular structure maintenance and stability, oxidative phosphorylation, and metabolism. The balance between metal deficiency and excess is typically ensured by several extracellular and intracellular mechanisms involved in uptake, distribution, and excretion. However, provoked by either intrinsic or extrinsic factors, excess iron, zinc, copper, or manganese can lead to cellular damage upon chronic or acute exposure, frequently attributed to oxidative stress. Intracellularly, mitochondria are the organelles that require the tightest control concerning reactive oxygen species production, which inevitably leaves them to be one of the most vulnerable targets of metal toxicity. Current therapies to counteract metal overload are focused on chelators, which often cause secondary effects decreasing patients' quality of life. New therapeutic options based on synthetic or natural antioxidants have proven positive effects against metal intoxication. In this review, we briefly address the cellular metabolism of transition metals, consequences of their overload, and current therapies, followed by their potential role in inducing oxidative stress and remedies thereof.

A water-soluble, cell-permeable Mn(ii) sensor enables visualization of manganese dynamics in live mammalian cells

Central roles of Mn2+ ions in immunity, brain function, and photosynthesis necessitate probes for tracking this essential metal ion in living systems. However, developing a cell-permeable, fluorescent sensor for selective imaging of Mn2+ ions in the aqueous cellular milieu has remained a challenge. This is because Mn2+ is a weak binder to ligand-scaffolds and Mn2+ ions quench fluorescent dyes leading to turn-off sensors that are not applicable for in vivo imaging. Sensors with a unique combination of Mn2+ selectivity, μM sensitivity, and response in aqueous media are necessary for not only visualizing labile cellular Mn2+ ions live, but also for measuring Mn2+ concentrations in living cells. No sensor has achieved this combination thus far. Here we report a novel, completely water-soluble, reversible, fluorescent turn-on, Mn2+ selective sensor, M4, with a K d of 1.4 μM for Mn2+ ions. M4 entered cells within 15 min of direct incubation and was applied to image Mn2+ ions in living mammalian cells in both confocal fluorescence intensity and lifetime-based set-ups. The probe was able to visualize Mn2+ dynamics in live cells revealing differential Mn2+ localization and uptake dynamics under pathophysiological versus physiological conditions. In a key experiment, we generated an in-cell Mn2+ response curve for the sensor which allowed the measurement of the endogenous labile Mn2+ concentration in HeLa cells as 1.14 ± 0.15 μM. Thus, our computationally designed, selective, sensitive, and cell-permeable sensor with a 620 nM limit of detection for Mn2+ in water provides the first estimate of endogenous labile Mn2+ levels in mammalian cells.

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.

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.

Heavy metals and metalloids exposure and liver function in Chinese adults - A nationally representative cross-sectional study

BACKGROUND

In China, the effects of heavy metals and metalloids (HMMs) on liver health are not consistently documented, despite their prevalent environmental presence.

OBJECTIVE

Our research assessed the association between HMMs and liver function biomarkers in a comprehensive sample of Chinese adults.

METHODS

We analyzed data from 9445 participants in the China National Human Biomonitoring survey. Blood and urine were evaluated for HMM concentrations, and liver health was gauged using serum albumin (ALB), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) metrics. Various statistical methods were employed to understand the relationship between 11 HMMs and liver function, adjusting for multiple factors. We also explored interactions with alcohol intake, gender, and age.

RESULTS

Among HMMs, selenium in blood [weighted geometric mean (GM) = 95.56 μg/L] and molybdenum in urine (GM = 46.44 μg/L) showed the highest concentrations, while lead in blood (GM = 21.92 μg/L) and arsenic in urine (GM = 19.80 μg/L) had the highest levels among risk HMMs. Manganese and thallium consistently indicated potential risk factor to liver in both sample types, while selenium displayed potential liver protection. Blood HMM mixtures were negatively associated with ALB (β = -0.614, 95% CI: -0.809, -0.418) and positively with AST (β = 0.701, 95% CI: 0.290, 1.111). No significant associations were found in urine HMM mixtures. Manganese, tin, nickel, and selenium were notable in blood mixture associations, with selenium and cobalt being significant in urine. The relationship of certain HMMs varied based on alcohol consumption.

CONCLUSION

This research highlights the complex relationship between HMM exposure and liver health in Chinese adults, particularly emphasizing metals like manganese, thallium, and selenium. The results suggest a need for public health attention to low dose HMM exposure and underscore the potential benefits of selenium for liver health. Further studies are essential to establish causality.

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.

Heavy metal and trace element alterations in patients during a migraine attack

OBJECTIVE

The aim of the study was to determine the heavy metal and trace element (HMTE) profile in patients with migraine (PwM) and to compare it to that of healthy individuals without migraine.

BACKGROUND

Migraine is a universal disease that affects more than 10% of the world's population; however, its pathophysiology is still obscure.

METHODS

A total of 100 participants were included in this prospective matched case-control study (50 PwM during acute attack and 50 age- and sex-matched healthy controls). The study was conducted in the university hospital in Yozgat, Turkey, where the inductively coupled plasma mass spectrometry system was used to measure the HMTE profile. The calibration curve was created with 11 points for heavy metals (arsenic [As], cadmium [Cd], cobalt [Co], lead [Pb], mercury [Hg], nickel [Ni], and tin [Sn]) and trace elements (antimony [Sb], chromium [Cr], copper [Cu], iron [Fe], magnesium [Mg], manganese [Mn], molybdenum [Mo], and zinc [Zn]).

RESULTS

The median age was 27 (23-37) years, and the female/male ratio was 37/13 for both groups. The PwM group had significantly higher As, Co, Pb, and Ni levels among the heavy metals (p = 0.033, 0.017, 0.022, and 0.021, respectively). Also, PwM had significantly lower Cr, Mg, and Zn levels among the trace elements (p = 0.007, 0.024, and < 0.001, respectively). The only trace element that was elevated in the PwM group was Mn (p = 0.001). The PwM and control groups did not differ in terms of Cd, Sn, Sb, Cu, Fe, and Mo (p = 0.165, 0.997, 0.195, 0.408, 0.440, and 0.252, respectively).

CONCLUSION

Some HMTE parameters are altered in PwM, which may provide additional insight into understanding migraine etiology.

Metal mixture exposures and serum lipid levels in childhood: the Rhea mother-child cohort in Greece

BACKGROUND

Growing evidence suggests that cardiovascular disease develops over the lifetime, often beginning in childhood. Metal exposures have been associated with cardiovascular disease and important risk factors, including dyslipidemia, but prior studies have largely focused on adult populations and single metal exposures.

OBJECTIVE

To investigate the individual and joint impacts of multiple metal exposures on lipid levels during childhood.

METHODS

This cross-sectional study included 291 4-year-old children from the Rhea Cohort Study in Heraklion, Greece. Seven metals (manganese, cobalt, selenium, molybdenum, cadmium, mercury, and lead) were measured in whole blood using inductively coupled plasma mass spectrometry. Serum lipid levels included total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol. To determine the joint and individual impacts of child metal exposures (log2-transformed) on lipid levels, Bayesian kernel machine regression (BKMR) was employed as the primary multi-pollutant approach. Potential effect modification by child sex and childhood environmental tobacco smoke exposure was also evaluated.

RESULTS

BKMR identified a positive association between the metal mixture and both total and LDL cholesterol. Of the seven metals examined, selenium (median 90.6 [IQR = 83.6, 96.5] µg/L) was assigned the highest posterior inclusion probability for both total and LDL cholesterol. A difference in LDL cholesterol of 8.22 mg/dL (95% CI = 1.85, 14.59) was observed when blood selenium was set to its 75th versus 25th percentile, holding all other metals at their median values. In stratified analyses, the positive association between selenium and LDL cholesterol was only observed among boys or among children exposed to environmental tobacco smoke during childhood.

IMPACT STATEMENT

Growing evidence indicates that cardiovascular events in adulthood are the consequence of the lifelong atherosclerotic process that begins in childhood. Therefore, public health interventions targeting childhood cardiovascular risk factors may have a particularly profound impact on reducing the burden of cardiovascular disease. Although growing evidence supports that both essential and nonessential metals contribute to cardiovascular disease and risk factors, such as dyslipidemia, prior studies have mainly focused on single metal exposures in adult populations. To address this research gap, the current study investigated the joint impacts of multiple metal exposures on lipid concentrations in early childhood.

Pharmaceutical Quality by Design Approach to Develop High-Performance Nanoparticles for Magnetic Hyperthermia

Magnetic hyperthermia holds significant therapeutic potential, yet its clinical adoption faces challenges. One obstacle is the large-scale synthesis of high-quality superparamagnetic iron oxide nanoparticles (SPIONs) required for inducing hyperthermia. Robust and scalable manufacturing would ensure control over the key quality attributes of SPIONs, and facilitate clinical translation and regulatory approval. Therefore, we implemented a risk-based pharmaceutical quality by design (QbD) approach for SPION production using flame spray pyrolysis (FSP), a scalable technique with excellent batch-to-batch consistency. A design of experiments method enabled precise size control during manufacturing. Subsequent modeling linked the SPION size (6-30 nm) and composition to intrinsic loss power (ILP), a measure of hyperthermia performance. FSP successfully fine-tuned the SPION composition with dopants (Zn, Mn, Mg), at various concentrations. Hyperthermia performance showed a strong nonlinear relationship with SPION size and composition. Moreover, the ILP demonstrated a stronger correlation to coercivity and remanence than to the saturation magnetization of SPIONs. The optimal operating space identified the midsized (15-18 nm) Mn0.25Fe2.75O4 as the most promising nanoparticle for hyperthermia. The production of these nanoparticles on a pilot scale showed the feasibility of large-scale manufacturing, and cytotoxicity investigations in multiple cell lines confirmed their biocompatibility. In vitro hyperthermia studies with Caco-2 cells revealed that Mn0.25Fe2.75O4 nanoparticles induced 80% greater cell death than undoped SPIONs. The systematic QbD approach developed here incorporates process robustness, scalability, and predictability, thus, supporting the clinical translation of high-performance SPIONs for magnetic hyperthermia.

Prevalence rates of neurodegenerative diseases versus human exposures to heavy metals across the United States

Novel means are needed to identify individuals and subpopulations susceptible to and afflicted by neurodegenerative diseases (NDDs). This study aimed to utilize geographic distribution of heavy metal sources and sinks to investigate a potential human health risk of developing NDDs. Known or hypothesized environmental factors driving disease prevalence of Alzheimer's Disease (AD), Parkinson's Disease (PD), and amyotrophic lateral sclerosis (ALS) are heavy metals, including arsenic (As), cadmium (Cd), manganese (Mn) and mercury (Hg). Lead (Pb) has been associated with AD and ALS. Analyzable mediums of human exposure to heavy metals (i.e., toxic metals and metalloids), or proxies thereof, include infant blood, topsoil, sewage sludge, and well water. U.S. concentrations of heavy metals in topsoil, sewage sludge, well water, and infant blood were mapped and compared to prevalence rates of major NDDs. Data from federal and state agencies (i.e., CDC, EPA, and the US Geological Survey) on heavy metal concentrations, age distribution, and NDD prevalence rates were geographically represented and statistically analyzed to quantify possible correlations. Aside from an expected significant association between NDD prevalence and age (p < 0.0001), we found significant associations between the prevalence of the sum of three major NDDs with: Pb in topsoil (p = 0.0433); Cd (p < 0.0001) and Pb (p < 0.0001) in sewage sludge; Pb in infant blood (p < 0.0001). Concentrations in sewage sludge of Cd and Pb were significantly correlated with NDD prevalence rates with an odds ratio of 2.91 (2.04, 4.225 95%CI) and 4.084 (3.14, 5.312 95%CI), respectively. The presence of toxic metals in the U.S. environment in multiple matrices, including sewage sludge, was found to be significantly associated with NDD prevalence. This is the first use of sewage sludge as an environmental proxy matrix to infer risk of developing NDDs.

Neurotoxicology of dopamine: Victim or assailant?

Since the identification of dopamine as a neurotransmitter in the mid-20th century, investigators have examined the regulation of dopamine homeostasis at a basic biological level and in human disorders. Genetic animal models that manipulate the expression of proteins involved in dopamine homeostasis have provided key insight into the consequences of dysregulated dopamine. As a result, we have come to understand the potential of dopamine to act as an endogenous neurotoxin through the generation of reactive oxygen species and reactive metabolites that can damage cellular macromolecules. Endogenous factors, such as genetic variation and subcellular processes, and exogenous factors, such as environmental exposures, have been identified as contributors to the dysregulation of dopamine homeostasis. Given the variety of dysregulating factors that impact dopamine homeostasis and the potential for dopamine itself to contribute to further cellular dysfunction, dopamine can be viewed as both the victim and an assailant of neurotoxicity. Parkinson's disease has emerged as the exemplar case study of dopamine dysregulation due to the genetic and environmental factors known to contribute to disease risk, and due to the evidence of dysregulated dopamine as a pathologic and pathogenic feature of the disease. This review, inspired by the talk, "Dopamine in Durham: location, location, location" presented by Dr. Miller for the Jacob Hooisma Memorial Lecture at the International Neurotoxicology Association meeting in 2023, offers a primer on dopamine toxicity covering endogenous and exogenous factors that disrupt dopamine homeostasis and the actions of dopamine as an endogenous neurotoxin.

Assessment of Human Health Risk Indices Due to Metal Contamination in the Surface Water of the Negro River Sub-Basin, Áncash

The accelerated loss of glacial cover in the Cordillera Blanca in Áncash, Peru, exposes the underlying rocks with high concentrations of sulfides from the Chicama Formation to oxidation and leaching processes, generating acid rock drainage (ARD) in glacial and periglacial areas. These are transported by surface runoff, contaminating the surface water with high concentrations of metals and sulfates, as well as increasing the acidity, which poses a risk to human health and the ecosystem. Therefore, the risk indices for human health due to metal contamination were evaluated at 19 surface water sampling points distributed in the Río Negro sub-basin. Hydrochemical analyses revealed average metal concentrations in the following order: Fe (28.597 mg/L), Al (3.832 mg/L), Mn (1.085 mg/L), Zn (0.234 mg/L), Ni (0.085 mg/L), Co (0.053 mg/L), Li (0.036 mg/L), Cu (0.005 mg/L), and Pb (0.002 mg/L). The risk was determined by calculating the Heavy Metal Pollution Index (HPI) and the Hazard Index (HI). The average HPI value was 360.959, indicating a high level of contamination (HPI ≥ 150). The human health risk assessment indicated that adverse effects caused by iron, lithium, and cobalt in children and adults should be considered. Through the use of Pearson correlation analysis, principal component analysis, and cluster analysis, it was identified that SO42-, Fe, S, Al, Co, Mn, Ni, Zn, and Li originate from natural sources, associated with the generation of ARD in glacial and periglacial areas.

Variability of the Ionome of Wild Boar (Sus scrofa) and Red Deer (Cervus elaphus) in a Dutch National Park, with Implications for Biomonitoring

The ionome-an important expression of the physiological state of organisms-is poorly known for mammals. The focus on particular tissues-such as liver, kidney, and bones-in biomonitoring of environmental pollution and potential deficiencies is based on widely held assumptions rather than solid knowledge of full mammalian ionomes. We examined the full ionome of Red deer (Cervus elaphus) and Wild boar (Sus scrofa), two commonly used mammals for biomonitoring, in a Dutch protected nature reserve (Veluwezoom). We used four individuals per species. We dissected 13 tissues and organs from each individuals (eight in total) of each species and measured 22 elemental concentrations in each. We assessed, for each element, how concentrations varied across tissues within and between individuals. Based on existing literature, we put our findings in the context of their function in the mammalian body. We found that the ionome was highly variable between as well as within the two species. For most elements, tissues containing the highest and lowest concentration differed between individuals. No single tissue accurately represented the accumulation of toxic elements or potential deficiencies in the bodies. Our assessment of the element's biological roles revealed a serious lack of reference values. Our findings imply that analyses of commonly used tissues in biomonitoring do not necessarily capture bioaccumulation of toxins or potential deficiencies. We recommend establishing a centralized database of mammalian ionomes to derive reference values in future. To our knowledge, our study is one of the most complete assessments of mammalian ionomes to date.

Role of antioxidants in the neurobiology of drug addiction: An update

Relationships between protective enzymatic and non-enzymatic pro-antioxidant mechanisms and addictive substances use disorders (SUDs) are analyzed here, based on the results of previous research, as well as on the basis of our current own studies. This review introduces new aspects of comparative analysis of associations of pro-antixidant and neurobiological effects in patients taking psychoactive substances and complements very limited knowledge about relationships with SUDs from different regions, mainly Europe. In view of the few studies on relations between antioxidants and neurobiological processes acting in patients taking psychoactive substances, this review is important from the point of view of showing the state of knowledge, directions of diagnosis and treatment, and further research needed explanation. We found significant correlations between chemical elements, pro-antioxidative mechanisms, and lipoperoxidation in the development of disorders associated with use of addictive substances, therefore elements that show most relations (Pr, Na, Mn, Y, Sc, La, Cr, Al, Ca, Sb, Cd, Pb, As, Hg, Ni) may be significant factors shaping SUDs. The action of pro-antioxidant defense and lipid peroxidation depends on the pro-antioxidative activity of ions. We explain the strongest correlations between Mg and Sb, and lipoperoxidation in addicts, which proves their stimulating effect on lipoperoxidation and on the induction of oxidative stress. We discussed which mechanisms and neurobiological processes change susceptibility to SUDs. The innovation of this review is to show that addicted people have lower activity of dismutases and peroxidases than healthy ones, which indicates disorders of antioxidant system and depletion of enzymes after long-term tolerance of stressors. We explain higher level of catalases, reductases, ceruloplasmin, bilirubin, retinol, α-tocopherol and uric acid of addicts. In view of poorly understood factors affecting addiction, analysis of interactions allows for more effective understanding of pathogenetic mechanisms leading to formation of addiction and development the initiation of directed, more effective treatment (pharmacological, hormonal) and may be helpful in the diagnosis of psychoactive changes.

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.

RGD targeted magnetic ferrite nanoparticles enhance antitumor immunotherapeutic efficacy by activating STING signaling pathway

Manganese has been used in tumor imaging for their ability to provide T1-weighted MRI signal. Recent research find Mn2+ can induce activation of the stimulator of interferon gene (STING) pathway to create an active and favorable tumor immune microenvironment. However, the direct injection of Mn2+ often results in toxicity. In this study, we developed an RGD targeted magnetic ferrite nanoparticle (RGD-MnFe2O4) to facilitate tumor targeted imaging and improve tumor immunotherapy. Magnetic resonance imaging and fluorescence molecular imaging were performed to monitor its in vivo biodistribution. We found that RGD-MnFe2O4 showed active tumor targeting and longer accumulation at tumor sites. Moreover, RGD-MnFe2O4 can activate STING pathway with low toxicity to enhance the PD-L1 expression. Furthermore, combining RGD-MnFe2O4 and anti-PD-L1 antibody (aPD-L1) can treat several types of immunogenic tumors through promoting the accumulation of tumor-infiltrating cytotoxic T cells. In general, our study provides a promising new strategy for the targeted and multifunctional theranostic nanoparticle for the improvement of tumor immunotherapy.

Manganese and Vanadium Co-Exposure Induces Severe Neurotoxicity in the Olfactory System: Relevance to Metal-Induced Parkinsonism

Chronic environmental exposure to toxic heavy metals, which often occurs as a mixture through occupational and industrial sources, has been implicated in various neurological disorders, including Parkinsonism. Vanadium pentoxide (V2O5) typically presents along with manganese (Mn), especially in welding rods and high-capacity batteries, including electric vehicle batteries; however, the neurotoxic effects of vanadium (V) and Mn co-exposure are largely unknown. In this study, we investigated the neurotoxic impact of MnCl2, V2O5, and MnCl2-V2O5 co-exposure in an animal model. C57BL/6 mice were intranasally administered either de-ionized water (vehicle), MnCl2 (252 µg) alone, V2O5 (182 µg) alone, or a mixture of MnCl2 (252 µg) and V2O5 (182 µg) three times a week for up to one month. Following exposure, we performed behavioral, neurochemical, and histological studies. Our results revealed dramatic decreases in olfactory bulb (OB) weight and levels of tyrosine hydroxylase, dopamine, and 3,4-dihydroxyphenylacetic acid in the treatment groups compared to the control group, with the Mn/V co-treatment group producing the most significant changes. Interestingly, increased levels of α-synuclein expression were observed in the substantia nigra (SN) of treated animals. Additionally, treatment groups exhibited locomotor deficits and olfactory dysfunction, with the co-treatment group producing the most severe deficits. The treatment groups exhibited increased levels of the oxidative stress marker 4-hydroxynonenal in the striatum and SN, as well as the upregulation of the pro-apoptotic protein PKCδ and accumulation of glomerular astroglia in the OB. The co-exposure of animals to Mn/V resulted in higher levels of these metals compared to other treatment groups. Taken together, our results suggest that co-exposure to Mn/V can adversely affect the olfactory and nigral systems. These results highlight the possible role of environmental metal mixtures in the etiology of Parkinsonism.

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.

Manganese accumulation in red blood cells as a biomarker of manganese exposure and neurotoxicity

Although overexposure to manganese (Mn) is known to cause neurotoxic damage, effective exposure markers for assessing Mn loading in Mn-exposed workers are lacking. Here, we construct a Mn-exposed rat model to perform correlation analysis between Mn-induced neurological damage and Mn levels in various biological samples. We combine this analysis with epidemiological investigation to assess whether Mn concentrations in red blood cells (MnRBCs) and urine (MnU) can be used as valid exposure markers. The results show that Mn exposure resulted in neurotoxic damage in rats and that MnRBCs correlated well with neurological damage, showing potential as a novel Mn exposure biomarker. These findings provide a basis for health monitoring of Mn-exposed workers and the development of more appropriate biological exposure limits.

Manganese-based nanomaterials promote synergistic photo-immunotherapy: green synthesis, underlying mechanisms, and multiple applications

Single phototherapy and immunotherapy have individually made great achievements in tumor treatment. However, monotherapy has difficulty in balancing accuracy and efficiency. Combining phototherapy with immunotherapy can realize the growth inhibition of distal metastatic tumors and enable the remote monitoring of tumor treatment. The development of nanomaterials with photo-responsiveness and anti-tumor immunity activation ability is crucial for achieving photo-immunotherapy. As immune adjuvants, photosensitizers and photothermal agents, manganese-based nanoparticles (Mn-based NPs) have become a research hotspot owing to their multiple ways of anti-tumor immunity regulation, photothermal conversion and multimodal imaging. However, systematic studies on the synergistic photo-immunotherapy applications of Mn-based NPs are still limited; especially, the green synthesis and mechanism of Mn-based NPs applied in immunotherapy are rarely comprehensively discussed. In this review, the synthesis strategies and function of Mn-based NPs in immunotherapy are first introduced. Next, the different mechanisms and leading applications of Mn-based NPs in immunotherapy are reviewed. In addition, the advantages of Mn-based NPs in synergistic photo-immunotherapy are highlighted. Finally, the challenges and research focus of Mn-based NPs in combination therapy are discussed, which might provide guidance for future personalized cancer therapy.

Associations of essential metals with the risk of aortic arch calcification: a cross-sectional study in a mid-aged and older population of Shenzhen, China

Vascular calcification is a strong predictor of cardiovascular events. Essential metals play critical roles in maintaining human health. However, the association of essential metal levels with risk of aortic arch calcification (AoAC) remains unclear. We measured the plasma concentrations of nine essential metals in a cross-sectional population and evaluated their individual and combined effects on AoAC risk using multiple statistical methods. We also explored the mediating role of fasting glucose. In the logistic regression model, higher quartiles of magnesium and copper were associated with the decreased AoAC risk, while higher quartile of manganese was associated with higher AoAC risk. The least absolute shrinkage and selection operator penalized regression analysis identified magnesium, manganese, calcium, cobalt, and copper as key metals associated with AoAC risk. The weighted quantile sum regression suggested a combined effect of metal mixture. A linear and positive dose-response relationship was found between manganese and AoAC in males. Moreover, blood glucose might mediate a proportion of 9.38% of the association between manganese exposure and AoAC risk. In summary, five essential metal levels were associated with AoAC and showed combined effect. Fasting glucose might play a significant role in mediating manganese exposure-associated AoAC risk.

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.

Manganese Nanoparticles: Synthesis, Mechanisms of Influence on Plant Resistance to Stress, and Prospects for Application in Agricultural Chemistry

Manganese (Mn) is an important microelement for the mineral nutrition of plants, but it is not effectively absorbed from the soil and mineral salts added thereto and can also be toxic in high concentrations. Mn nanoparticles (NPs) are less toxic, more effective, and economical than Mn salts due to their nanosize. This article critically reviews the current publications on Mn NPs, focusing on their effects on plant health, growth, and stress tolerance, and explaining possible mechanisms of their effects. This review also provides basic information and examples of chemical, physical, and ecological ("green") methods for the synthesis of Mn NPs. It has been shown that the protective effect of Mn NPs is associated with their antioxidant activity, activation of systemic acquired resistance (SAR), and pronounced antimicrobial activity against phytopathogens. In conclusion, Mn NPs are promising agents for agriculture, but their effects on gene expression and plant microbiome require further research.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Minerals and the Menstrual Cycle: Impacts on Ovulation and Endometrial Health

The role of minerals in female fertility, particularly in relation to the menstrual cycle, presents a complex area of study that underscores the interplay between nutrition and reproductive health. This narrative review aims to elucidate the impacts of minerals on key aspects of the reproductive system: hormonal regulation, ovarian function and ovulation, endometrial health, and oxidative stress. Despite the attention given to specific micronutrients in relation to reproductive disorders, there is a noticeable absence of a comprehensive review focusing on the impact of minerals throughout the menstrual cycle on female fertility. This narrative review aims to address this gap by examining the influence of minerals on reproductive health. Each mineral's contribution is explored in detail to provide a clearer picture of its importance in supporting female fertility. This comprehensive analysis not only enhances our knowledge of reproductive health but also offers clinicians valuable insights into potential therapeutic strategies and the recommended intake of minerals to promote female reproductive well-being, considering the menstrual cycle. This review stands as the first to offer such a detailed examination of minerals in the context of the menstrual cycle, aiming to elevate the understanding of their critical role in female fertility and reproductive health.

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.

Expression levels of key immune indicators and immune checkpoints in manganese-exposed rats

Manganese is essential trace elements, to participate in the body a variety of biochemical reactions, has important physiological functions, such as stimulate the immune cell proliferation, strengthen the cellular immunity, etc. However, excessive manganese exposure can cause damage to multiple systems of the body.The immune system is extremely vulnerable to external toxicants, however manganese research on the immune system are inadequate and biomarkers are lacking. Therefore, here we applied a manganese-exposed rat model to make preliminary observations on the immunotoxic effects of manganese. We found that manganese exposure inhibited humoral immune function in rats by decreasing peripheral blood IgG (ImmunoglobulinG, IgG), IgM (ImmunoglobulinM, IgM) and complement C3 levels; It also regulates rat cellular immune activity by influencing peripheral blood, spleen, and thymus T cell numbers and immune organ ICs (Immune Checkpoints, ICs) and cytokine expression. Furthermore, it was revealed that the impact of manganese exposure on the immune function of rats exhibited a correlation with both the dosage and duration of exposure. Notably, prolonged exposure to high doses of manganese had the most pronounced influence on rat immune function, primarily manifesting as immunosuppression.The above findings suggest that manganese exposure leads to impaired immune function and related changes in immune indicators, or may provide clues for the discovery of its biomarkers.

Breast cancer risk for the joint exposure to metals and metalloids in women: Results from the EPIC-Spain cohort

Environmental factors play a role in breast cancer development. While metals and metalloids (MMs) include some carcinogens, their association with breast cancer depends on the element studied. Most studies focus on individual MMs, but the combined effects of metal mixtures remain unclear. The aim of this study was to analyze the relationship between the joint exposure to MMs and the risk of developing female breast cancer. We conducted a case-control study within the multicenter prospective EPIC-Spain cohort. Study population comprised 292 incident cases and 286 controls. Plasma concentrations of 16 MMs were quantified at recruitment. Potential confounders were collected using a questionnaire and anthropometric measurements. Mixed-effects logistic regression models were built to explore the effect of individual MMs. Quantile-based g computation models were applied to identify the main mixture components and to estimate the joint effect of the metal mixture. The geometric means were highest for Cu (845.6 ng/ml) and Zn (604.8 ng/ml). Cases had significantly higher Cu concentrations (p = 0.010) and significantly lower Zn concentrations (p < 0.001). Cu (+0.42) and Mn (+0.13) showed the highest positive weights, whereas Zn (-0.61) and W (-0.16) showed the highest negative weights. The joint effect of the metal mixture was estimated at an OR = 4.51 (95%CI = 2.32-8.79), suggesting a dose-response relationship. No evidence of non-linearity or non-additivity was found. An unfavorable exposure profile, primarily characterized by high Cu and low Zn levels, could lead to a significant increase in the risk of developing female breast cancer. Further studies are warranted to confirm these findings.

Neuroprotective Effect of Resveratrol against Manganese-Induced Oxidative Stress and Matrix Metalloproteinase-9 in an "In Vivo" Model of Neurotoxicity

Chronic exposure to manganese (Mn) leads to its accumulation in the central nervous system (CNS) and neurotoxicity with not well-known mechanisms. We investigated the involvement of matrix metalloproteinase (MMP)-2 and -9 in Mn neurotoxicity in an in vivo model of rats treated through an intraperitoneal injection, for 4 weeks, with 50 mg/kg of MnCl2 in the presence or in the absence of 30 mg/kg of resveratrol (RSV). A loss of weight was observed in Mn-treated rats compared with untreated and RSV-treated rats. A progressive recovery of body weight was detected in rats co-treated with Mn and RSV. The analysis of brain homogenates indicated that RSV counteracted the Mn-induced increase in MMP-9 levels and reactive oxygen species production as well as the Mn-induced decrease in superoxide dismutase activity and glutathione content. In conclusion, Mn exposure, resulting in MMP-9 induction with mechanisms related to oxidative stress, represents a risk factor for the development of CNS diseases.

Metalloproteins and metalloproteomics in health and disease

Metalloproteins represents more than one third of human proteome, with huge variation in physiological functions and pathological implications, depending on the metal/metals involved and tissue context. Their functions range from catalysis, bioenergetics, redox, to DNA repair, cell proliferation, signaling, transport of vital elements, and immunity. The human metalloproteomic studies revealed that many families of metalloproteins along with individual metalloproteins are dysregulated under several clinical conditions. Also, several sorts of interaction between redox- active or redox- inert metalloproteins are observed in health and disease. Metalloproteins profiling shows distinct alterations in neurodegenerative diseases, cancer, inflammation, infection, diabetes mellitus, among other diseases. This makes metalloproteins -either individually or as families- a promising target for several therapeutic approaches. Inhibitors and activators of metalloenzymes, metal chelators, along with artificial metalloproteins could be versatile in diagnosis and treatment of several diseases, in addition to other biomedical and industrial applications.

Manganese Exacerbates ConA-Induced Liver Inflammation via the cGAS-STING Signaling Pathway

There is a potential association between the dysregulation of trace elements and impaired liver function. Elevated levels of manganese, an essential metal ion, have been observed in liver-related diseases, and excessive intake of manganese can worsen liver damage. However, the specific mechanisms underlying manganese-induced liver injury are not well understood. The aim of our study was to investigate the effects of excess manganese on autoimmune hepatitis (AIH) and elucidate its mechanisms. Our findings revealed that manganese exacerbates liver damage under ConA-induced inflammatory conditions. Transcriptomic and experimental data suggested that manganese enhances inflammatory signaling and contributes to the inflammatory microenvironment in the liver of AIH mice. Further investigations demonstrated that manganese exacerbates liver injury by activating the cGAS-STING signaling pathway and its downstream pro-inflammatory factors such as IFN[Formula: see text], IFN[Formula: see text], TNF[Formula: see text], and IL-6 in the liver of AIH mice. These results suggest that manganese overload promotes the progression of AIH by activating cGAS-STING-mediated inflammation, providing a new perspective for the treatment and prognosis of AIH.

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.

Preparation, characterization, and adsorption kinetics of graphene oxide/chitosan/carboxymethyl cellulose composites for the removal of environmentally relevant toxic metals

This study attempted to develop a low-cost and eco-friendly bio-based composite adsorbent that is highly efficient in capturing potential toxic metals. The bio-composite adsorbent was prepared using graphene oxide (GO), carboxymethyl cellulose (CMC) and chitosan (CS); and characterized using FTIR, SEM-EDX and WAXD techniques. Metal-ion concentration in an aqueous solution was measured by ICP-OES. This article reveals that the adsorption of heavy metal ions varied according to the adsorbent quantity, initial metal concentration, pH, and interaction time. The metal ions' adsorption capacity (mg/g) was observed to increase when the interaction time and metal concentration increased. Conversely, metal ions adsorption was decreased with an increase in adsorbent dosages. The effect of pH on metal ions' adsorption was ion-specific. The substantial adsorption by GO/CMC/CS composite for Co2+, CrO42-, Mn2+ and Cd2+, had the respective values of 43.55, 77.70, 57.78, and 91.38 mg/g under acidic conditions. The metal ions experimental data were best fitted with pseudo-second-order (PSO) kinetics, and Freundlich isotherm model (except Co2+). The separation factors (RL) value in the present investigation were found between 0 and 1, meaning that the metal ions adsorption onto GO/CS/CMC composite is favorable. The RL and sorption intensity (1/n) values fitted well to the adsorption isotherm.

Advances in the Involvement of Metals and Metalloids in Plant Defense Response to External Stress

Plants, as sessile organisms, uptake nutrients from the soil. Throughout their whole life cycle, they confront various external biotic and abiotic threats, encompassing harmful element toxicity, pathogen infection, and herbivore attack, posing risks to plant growth and production. Plants have evolved multifaceted mechanisms to cope with exogenous stress. The element defense hypothesis (EDH) theory elucidates that plants employ elements within their tissues to withstand various natural enemies. Notably, essential and non-essential trace metals and metalloids have been identified as active participants in plant defense mechanisms, especially in nanoparticle form. In this review, we compiled and synthetized recent advancements and robust evidence regarding the involvement of trace metals and metalloids in plant element defense against external stresses that include biotic stressors (such as drought, salinity, and heavy metal toxicity) and abiotic environmental stressors (such as pathogen invasion and herbivore attack). We discuss the mechanisms underlying the metals and metalloids involved in plant defense enhancement from physiological, biochemical, and molecular perspectives. By consolidating this information, this review enhances our understanding of how metals and metalloids contribute to plant element defense. Drawing on the current advances in plant elemental defense, we propose an application prospect of metals and metalloids in agricultural products to solve current issues, including soil pollution and production, for the sustainable development of agriculture. Although the studies focused on plant elemental defense have advanced, the precise mechanism under the plant defense response still needs further investigation.

Divalent metal content in diet affects severity of manganese toxicity in Drosophila

Dysregulation of manganese (Mn) homeostasis is a contributing factor in many neuro-degenerative diseases. Adult Drosophila are sensitive to excessive levels of dietary Mn, dying relatively early, and exhibiting biochemical and mobility changes reminiscent of Parkinsonian conditions. To further study Mn homeostasis in Drosophila, we sought to test lower levels of dietary Mn (5 mM) and noted a striking difference in Canton-S adult survivorship on different food. On a cornmeal diet, Mn-treated flies live only about half as long as untreated siblings. Yet, with the same Mn concentration in a molasses diet, adults survive about 80% as long as untreated siblings, and adults raised on a sucrose-yeast diet are completely insensitive to this low dose of dietary Mn. By manipulating metal ion content in the cornmeal diet, and measuring the metal content in each diet, we traced the difference in lifespan to the levels of calcium and magnesium in the food, suggesting that these ions are involved in Mn uptake and/or use. Based on these findings, it is recommended that the total dietary load of metal ions be considered when assessing Mn toxicity.

Associations between plasma metal/metalloid mixtures and the risk of central obesity: A prospective cohort study of Chinese adults

Central obesity has increased rapidly over the past decade and posed a substantial disease burden worldwide. Exposure to metals/metalloids has been acknowledged to be involved in the development of central obesity through regulation of cortisol, insulin resistance, and glucocorticoid receptor reduction. Despite the importance, it is lack of prospective study which comprehensively evaluate the relations between multiple metals exposure and central obesity. We explored the prospective associations of plasma metal concentrations with central obesity in a prospective study of the Dongfeng-Tongji cohort. The present study included 2127 participants with a 6.87-year mean follow-up duration. We measured 23 plasma metal/metalloid concentrations at baseline. The associations between metals and incident central obesity were examined utilizing the Cox proportional hazard regression in single and multiple metals models. Additionally, we applied elastic net (ENET), Bayesian kernel machine regression (BKMR), plasma metal score (PMS), and quantile-based g-computation (Qgcomp) models to explore the joint associations of metal mixtures with central obesity. After adjusting potential confounders, we found significant associations of plasma manganese (Mn) and thallium (Tl) concentrations with a higher risk of central obesity, whereas plasma rubidium (Rb) concentration was associated with a lower risk of central obesity both in single and multiple metals models (all FDR <0.05). The ENET and Qqcomp models verified similar metals (Mn, Rb, and Tl) as important predictors for central obesity. The results of both BKMR model and PMS suggested cumulative exposure to metal mixtures was associated with a higher risk of central obesity. Our findings suggested that co-exposure to metals was associated with a higher risk of central obesity. This study expands our knowledge that the management of metals/metalloids exposure may be beneficial for the prevention of new-onset central obesity, which may subsequently alleviate the disease burden of late-life health outcomes.

A comparison of field portable X-ray fluorescence (FP XRF) and inductively coupled plasma mass spectrometry (ICP-MS) for analysis of metals in the soil and ambient air

When analyzing metal concentrations in the soil and ambient air, accurate and reliable results are essential. Inductively coupled plasma mass spectrometry (ICP-MS) is considered the benchmark analytical method for environmental soil and air filter samples containing metals. Field portable X-ray fluorescence (FP XRF) can provide more timely results with lower ongoing costs, but the results are not as accurate as ICP-MS. The primary goal of this study was to find an optimal method to maximize the level of agreement between FP XRF results and ICP-MS results when analyzing metal concentrations in soil and ambient air samples in a U.S. Superfund community. Two different correction factor methods were tested to improve the prediction of ICP-MS concentrations using FP XRF for arsenic and lead in soil and ambient air. Ninety-one residential soil samples and 42 ambient air filter samples were analyzed in a split-half design, where half the samples were used to create the correction factors and the other half to evaluate the level of agreement between the analytical methods following FP XRF correction. Paired t-tests, linear regression plots, and Bland-Altman plots were utilized to examine which correction factor provided the highest level of agreement between the two methods. Based on the results from this study, it was determined that a ratio correction factor method provided the best fit for this FP XRF analytical device.

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.