Pallidal index as biomarker of manganese brain accumulation and associated with manganese levels in blood: a meta-analysis

Trace Elements Levels in Major Depressive Disorder-Evaluation of Potential Threats and Possible Therapeutic Approaches

The multifactorial etiology of major depressive disorder (MDD) includes biological, environmental, genetic, and psychological aspects. Recently, there has been an increasing interest in metallomic studies in psychiatry, aiming to evaluate the role of chosen trace elements in the MDD etiology as well as the progression of symptoms. This narrative review aims to summarize the available literature on the relationship between the concentration of chosen elements in the serum of patients with MDD and the onset and progression of this psychiatric condition. The authors reviewed PubMed, Web of Science, and Scopus databases searching for elements that had been investigated so far and further evaluated them in this paper. Ultimately, 15 elements were evaluated, namely, zinc, magnesium, selenium, iron, copper, aluminium, cadmium, lead, mercury, arsenic, calcium, manganese, chromium, nickel, and phosphorus. The association between metallomic studies and psychiatry has been developing dynamically recently. According to the results of current research, metallomics might act as a potential screening tool for patients with MDD while at the same time providing an assessment of the severity of symptoms. Either deficiencies or excessive amounts of chosen elements might be associated with the progression of depressive symptoms or even the onset of the disease among people predisposed to MDD.

Magnetic resonance spectroscopy and liquid chromatography-mass spectrometry metabolomics study may differentiate pre-eclampsia from gestational hypertension

OBJECTIVE

To investigate the findings of magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and serum metabolomics for differentiating pre-eclampsia (PE) from gestational hypertension (GH).

METHODS

This prospective study enrolled 176 subjects including a primary cohort with healthy non-pregnant women (HN, n = 35), healthy pregnant women (HP, n = 20), GH (n = 27), and PE (n = 39) and a validation cohort with HP (n = 22), GH (n = 22), and PE (n = 11). T1 signal intensity index (T1SI), apparent diffusion coefficient (ADC) value, and the metabolites on MRS were compared. The differentiating performances of single and combined MRI and MRS parameters for PE were evaluated. Serum liquid chromatography-mass spectrometry (LC-MS) metabolomics was investigated by sparse projection to latent structures discriminant analysis.

RESULTS

Increased T1SI, lactate/creatine (Lac/Cr), and glutamine and glutamate (Glx)/Cr and decreased ADC value and myo-inositol (mI)/Cr in basal ganglia were found in PE patients. T1SI, ADC, Lac/Cr, Glx/Cr, and mI/Cr yielded an area under the curves (AUC) of 0.90, 0.80, 0.94, 0.96, and 0.94 in the primary cohort, and of 0.87, 0.81, 0.91, 0.84, and 0.83 in the validation cohort, respectively. A combination of Lac/Cr, Glx/Cr, and mI/Cr yielded the highest AUC of 0.98 in the primary cohort and 0.97 in the validation cohort. Serum metabolomics analysis showed 12 differential metabolites, which are involved in pyruvate metabolism, alanine metabolism, glycolysis, gluconeogenesis, and glutamate metabolism.

CONCLUSIONS

MRS is expected to be a noninvasive and effective tool for monitoring GH patients to avoid the development of PE.

KEY POINTS

• Increased T1SI and decreased ADC value in the basal ganglia were found in PE patients than in GH patients. • Increased Lac/Cr and Glx/Cr, and decreased mI/Cr in the basal ganglia were found in PE patients than in GH patients. • LC-MS metabolomics showed that the major differential metabolic pathways between PE and GH were pyruvate metabolism, alanine metabolism, glycolysis, gluconeogenesis, and glutamate metabolism.

Magnetic resonance imaging T1 indices of the brain as biomarkers of inhaled manganese exposure

Excessive exposure to manganese (Mn) is linked to its accumulation in the brain and adverse neurological effects. Paramagnetic properties of Mn allow the use of magnetic resonance imaging (MRI) techniques to identify it in biological tissues. A critical review was conducted to evaluate whether MRI techniques could be used as a diagnostic tool to detect brain Mn accumulation as a quantitative biomarker of inhaled exposure. A comprehensive search was conducted in MEDLINE, EMBASE, and PubMed to identify potentially relevant studies published prior to 9 May 2022. Two reviewers independently screened identified references using a two-stage process. Of the 6452 unique references identified, 36 articles were retained for data abstraction. Eligible studies used T1-weighted MRI techniques and reported direct or indirect T1 measures to characterize Mn accumulation in the brain. Findings demonstrate that, in subjects exposed to high levels of Mn, deposition in the brain is widespread, accumulating both within and outside the basal ganglia. Available evidence indicates that T1 MRI techniques can be used to distinguish Mn-exposed individuals from unexposed. Additionally, T1 MRI may be useful for semi-quantitative evaluation of inhaled Mn exposure, particularly when interpreted along with other exposure indices. T1 MRI measures appear to have a nonlinear relationship to Mn exposure duration, with R1 signal only increasing after critical thresholds. The strength of the association varied depending on the regions of interest imaged and the method of exposure measurement. Overall, available evidence suggests potential for future clinical and risk assessment applications of MRI as a diagnostic tool.

Kinematic alignment versus mechanical alignment in primary total knee arthroplasty: an updated meta-analysis of randomized controlled trials

Background

The purpose of this study was to perform an updated meta-analysis to compare the outcomes of kinematic alignment (KA) and mechanical alignment (MA) in patients undergoing total knee arthroplasty.

Methods

PubMed, EMBASE, Web of Science, Google Scholar, and the Cochrane Library were systematically searched. Eligible randomized controlled trials regarding the clinical outcomes of patients undergoing total knee arthroplasty with KA and MA were included for the analysis.

Results

A total of 1112 participants were included in this study, including 559 participants with KA and 553 patients with MA. This study revealed that the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Society Score (knee and combined), and knee flexion range were better in the patients with kinematic alignment than in the mechanical alignment. In terms of radiological results, the femoral knee angle, mechanical medial proximal tibial angle, and joint line orientation angle were significantly different between the two techniques. Perioperatively, the walk distance before discharge was longer in the KA group than in the MA group. In contrast, other functional outcomes, radiological results, perioperative outcomes, and postoperative complication rates were similar in both the kinematic and mechanical alignment groups.

Conclusions

The KA technique achieved better functional outcomes than the mechanical technique in terms of KSS (knee and combined), WOMAC scores, and knee flexion range.

PROSPERO trial registration number CRD42021264519. Date registration: July 28, 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03097-2.

Welder's lung and brain MRI findings in manganese-exposed welders

BACKGROUND

Biomarkers of manganese (Mn) exposure and manganism are poorly understood. Blood Mn levels are often used to assess exposure, while brain Mn accumulation may be demonstrated by pallidal hyperintensity at magnetic resonance imaging (MRI). Mn-containing electrodes used in manual metal arc welding may be associated with the welder's lungs.

METHODS

A cross-sectional study was set up to compare T1 intensity in basal ganglia at MRI and Mn blood levels in subjects with or without pneumoconiosis. Clinical, radiological, pulmonary function and laboratory parameters were assessed among 154 welders referred to our hospital for suspected pulmonary pathology.

RESULTS

The study group included 123 male welders with pneumoconiosis (79.9%) and 31 welders without pulmonary damage (20.1%). The cases without pneumoconiosis were younger (38.5±6.6 vs 42.1±7.1, p=0.012). Cases with pneumoconiosis had blood lower Mn levels [13.5 (10-21)] as compared to those without pneumoconiosis [18.5 (7.8- 34)], p=0.035. In the same groups, the cases with high blood Mn levels were 49 (39.8%) and 18 (58.1%) p= 0.052, respectively. Brain MRI hyperintensity was found in 86 (55.8%) subjects with welder's lung 63 (51.2) but also in 23 (74.2) individuals without welder's lung. MRI hyperintensity in basal ganglia was significantly related to high blood Mn (p<0.005).

CONCLUSION

This is the first study evaluating blood Mn levels of welders and their correlation with pulmonary and neurological effects. Poor working conditions may be associated with exposure to Mn and fibrogenic fumes leading to chronic lung diseases and hyperintensity in brain MRI suggesting Mn accumulation.

Hypermanganesemia-Induced Cerebral Toxicity Mimicking an Acute Ischemic Stroke: A Case Report and Review of Overlapping Pathologies

Objective: To review and consider risk factors associated with the accumulation of and toxicity from manganese in patients receiving total parenteral nutrition (TPN). Case Summary: A 66-year-old female presented to the emergency department with right facial and arm weakness that initiated 1 hour prior to admission. Past medical history includes oral cancer with chronic aspiration and gastroparesis secondary to chemotherapy, TPN for 9 months, and a previous episode of right facial and arm parasthesias due to hypertensive emergency 4 years prior. The patient was assigned a National Institutes of Health Stroke Scale score of 6, cleared of an intracranial hemorrhage on imaging, and was administered tPA (tissue plasminogen activator) for an acute ischemic stroke after managing her hypertension to <185/110 mm Hg. Resolution of symptoms occurred within 24 hours. A magnetic resonance imaging of the patient's brain 24-hours post-tPA indicated an increased signal density in the globus pallidus, which in turn is linked with encephalopathy and has been described as a marker for hypermanganesemia. Discussion: Manganese is an essential trace element with a critical role in numerous physiologic functions. Though readily obtained from dietary sources and rarely causing issue, manganese provided to patients via TPN may result in toxicities. Though the presentation of neurotoxicities associated with TPN-delivered manganese has been previously documented, the clinical presentation of toxicity has never mimicked an acute ischemic stroke. Conclusion: Though an evaluation of overlapping pathologies is warranted, this patient's clinical presentation of manganese toxicity mimicked an acute ischemic stroke and resulted in the administration of a fibrinolytic. A more comprehensive appreciation of the implications of trace elements is demanded of clinicians.

Manganese Toxicity Associated With Total Parenteral Nutrition: A Review

Objective: To review hypermanganesemia-induced toxicities in adult patients receiving parenteral nutrition (PN) therapy. Data Sources: A comprehensive literature review was conducted from June 2020 to May 2021 on PubMED, MEDLINE, Scopus, ProQuest, the Cumulative Index of Nursing and Allied Health Literature (CINAHL), and Web of Science. Study Selection and Data Extraction: Keyword and Boolean phrase searches were conducted using the following terminology: "manganese" OR "manganesemia" OR "manganism" or "hypermanganesemia" AND "total parenteral nutrition" OR "PN" or "parenteral nutrition" AND "toxicity" OR "accumulation." Appropriate filters, including "humans" and "English" and NOT "reviews," were utilized on all databases to improve search outcomes. Data Synthesis: A total of 4 reports detailing hypermanganesemia in 57 patient encounters were included in this review. Significant heterogeneity exists with regard to the duration of manganese supplementation and the dose of manganese. Toxicity associated with manganese was observed in as few as 15 days. The dose of manganese, though likely governed by content in commercially available products, may regularly exceed the recommendations of clinical guidelines and should be limited to 55 µg/day. Select patients with underlying malignancy, those with significant and prolonged Vitamin D deficiency, or those who have acquired a SLC30A10 genetic mutation may be at an increased risk of developing manganese toxicity. Conclusions: Clinicians must be cognizant of the concentration of trace elements added to PN, as manganese, and perhaps other biometals, may accumulate when dosed above the recommended daily allowances.

PdpaMn inhibits fatty acid synthase-mediated glycolysis by down-regulating PI3K/Akt signaling pathway in breast cancer

Novel manganese complex, PdpaMn ([(Pdpa)MnCl2]), was developed to induce apoptosis in breast cancer cells. The impact of phosphoinositide-(3)-kinase pathway onto fatty acid synthase (FASN) has an effect on cellular metabolism in breast cancer. However, reverse actions from FASN towards PI3K/Akt are still indefinable. Perhaps, loss of FASN could regulate glycolysis. Previously we established that PdpaMn inhibits FASN and involve in mitochondrial function. This study investigated the activity of PdpaMn on glycolysis and its mechanism. PdpaMn was used to suppress FASN expression in tumor. Expression of ATP and lactic acid level was measured to investigate the glycolysis variance in cells and animals. MCF-7 and 4T1 cells were treated with G28UCM, an inhibitor of FASN and PdpaMn, western blotting to detect PI3K/Akt signaling pathway. The capacity of proliferation was investigated by western blotting and immunohistochemistry. PdpaMn selectively inhibits cancer cells and tumor growth but also block FASN expression and suppresses the content of free fatty acid. Lactate dehydrogenase (LDHA) protein level was down-regulated as G28UCM and PdpaMn inhibited FASN, glucose transporter (Glut1), and pyruvate kinase (PKM2) proteins level were not affected. PI3K, p-Akt in the experimental group evidently declined compared to the control group. Proliferation was suppressed in FASN-arbitrated glycolysis. Our study supports the hypothesis that loss of FASN by PdpaMn suppressed glycolysis via down-regulating PI3K/Akt signaling pathway revealing the direct link between FASN and glycolysis. The results have paved the way to unravel the mechanisms of FASN and mitochondrial will be useful for designing novel co-targeting strategies for breast cancer.

[11C]dihydrotetrabenazine Positron Emission Tomography in Manganese-Exposed Workers

OBJECTIVE

To understand the neurotoxic effects of manganese (Mn) exposure on monoaminergic function, utilizing [C]dihydrotetrabenazine (DTBZ) positron emission tomography (PET) to measure vesicular monoamine transporter 2 (VMAT2).

METHODS

Basal ganglia and thalamic DTBZ binding potentials (BPND) were calculated on 56 PETs from 41 Mn-exposed workers. Associations between cumulative Mn exposure, regional BPND, and parkinsonism were examined by mixed linear regression.

RESULTS

Thalamic DTBZ BPND was inversely associated with exposure in workers with less than 3 mg Mn/m-yrs, but subsequently remained stable. Pallidal DTBZ binding increased in workers with less than 2 mg Mn/m-yrs of exposure, but decreased thereafter. Thalamic DTBZ binding was inversely associated with parkinsonism (P = 0.003).

CONCLUSION

Mn-dose-dependent associations with thalamic and pallidal DTBZ binding indicate direct effects on monoaminergic VMAT2. Thalamic DTBZ binding was also associated with parkinsonism, suggesting potential as an early biomarker of Mn neurotoxicity.

Inherited Manganese Disorders and the Brain: What Neurologists Need to Know

Although acquired manganese neurotoxicity has been widely reported since its first description in 1837 and is popularly referred to as "manganism," inherited disorders of manganese homeostasis have received the first genetic signature as recently as 2012. These disorders, predominantly described in children and adolescents, involve mutations in three manganese transporter genes, i.e., SLC30A10 and SLC39A14 which lead to manganese overload, and SLC39A8, which leads to manganese deficiency. Both disorders of inherited hypermanganesemia typically exhibit dystonia and parkinsonism with relatively preserved cognition and are differentiated by the occurrence of polycythemia and liver involvement in the SLC30A10-associated condition. Mutations in SLC39A8 lead to a congenital disorder of glycosylation which presents with developmental delay, failure to thrive, intellectual impairment, and seizures due to manganese deficiency. Chelation with iron supplementation is the treatment of choice in inherited hypermanganesemia. In this review, we highlight the pathognomonic clinical, laboratory, imaging features and treatment modalities for these rare disorders.

MRI Signal Intensity and Parkinsonism in Manganese-Exposed Workers

OBJECTIVE

T1-weighted brain magnetic resonance imaging (MRI) of the basal ganglia provides a noninvasive measure of manganese (Mn) exposure, and may also represent a biomarker for clinical neurotoxicity.

METHODS

We acquired T1-weighted MRI scans in 27 Mn-exposed welders, 12 other Mn-exposed workers, and 29 nonexposed participants. T1-weighted intensity indices were calculated for four basal ganglia regions. Cumulative Mn exposure was estimated from work history data. Participants were examined using the Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3).

RESULTS

We observed a positive dose-response association between cumulative Mn exposure and the pallidal index (PI) (β = 2.33; 95% confidence interval [CI], 0.93 to 3.74). There was a positive relationship between the PI and UPDRS3 (β = 0.15; 95% CI, 0.03 to 0.27).

CONCLUSION

The T1-weighted pallidal signal is associated with occupational Mn exposure and severity of parkinsonism.

Manganese Exposure and Neurologic Outcomes in Adult Populations

A review of published articles examining the effects of manganese exposure to workers and community residents shows adverse neurologic outcomes. Innovative biomarkers, including those from neuroimaging, were incorporated into many of these studies to assess both manganese exposure and neurologic outcomes. A variety of health effects were evaluated, including cognitive and motor impairments. Studies of community participants residing near manganese point sources show variability in outcomes, reflecting the complexities of exposure measurement, individual absorption, and assessment of neurologic effects. The aging population provides insight into the impacts of chronic exposure in younger populations.

Dietary Manganese Exposure in the Adult Population in Germany-What Does it Mean in Relation to Health Risks?

Manganese is both an essential nutrient and a potential neurotoxicant. Therefore, the question arises whether the dietary manganese intake in the German population is on the low or high side. Results from a pilot total diet study in Germany presented here reveal that the average dietary manganese intake in the general population in Germany aged 14-80 years is about 2.8 mg day^-1 for a person of 70 kg body weight. This exposure level is within the intake range of 2-5 mg per person and day as recommended by the societies for nutrition in Germany, Austria, and Switzerland. No information on the dietary exposure of children in Germany can be provided so far. Although reliable information on health effects related to oral manganese exposure is limited, there is no indication from the literature that these dietary intake levels are associated with adverse health effects either by manganese deficiency or excess. However, there is limited evidence that manganese taken up as a highly bioavailable bolus, for example, uptake via drinking water or food supplements, could pose a potential risk to human health-particularly in certain subpopulations-when certain intake amounts, which are currently not well defined, are exceeded.

Genetic Disorders of Manganese Metabolism

Purpose of Review

This article provides an overview of the pathogenesis, clinical presentation and treatment of inherited manganese transporter defects.

Recent Findings

Identification of a new group of manganese transportopathies has greatly advanced our understanding of how manganese homeostasis is regulated in vivo. While the manganese efflux transporter SLC30A10 and the uptake transporter SLC39A14 work synergistically to reduce the manganese load, SLC39A8 has an opposing function facilitating manganese uptake into the organism. Bi-allelic mutations in any of these transporter proteins disrupt the manganese equilibrium and lead to neurological disease: Hypermanganesaemia with dystonia 1 (SLC30A10 deficiency) and hypermanganesaemia with dystonia 2 (SLC39A14 deficiency) are characterised by manganese neurotoxicity while SLC39A8 mutations cause a congenital disorder of glycosylation type IIn due to Mn deficiency.

Summary

Inherited manganese transporter defects are an important differential diagnosis of paediatric movement disorders. Manganese blood levels and MRI brain are diagnostic and allow early diagnosis to avoid treatment delay.

Analysis of Trace Elements in Human Brain: Its Aim, Methods, and Concentration Levels

Trace elements play a crucial role in many biochemical processes, mainly as components of vitamins and enzymes. Although small amounts of metal ions have protective properties, excess metal levels result in oxidative injury, which is why metal ion homeostasis is crucial for the proper functioning of the brain. The changes of their level in the brain have been proven to be a risk factor for Alzheimer's, Parkinson's, and Huntington's diseases, as well as amyotrophic lateral sclerosis. Therefore, it is currently an important application of various analytical methods. This review covers the most important of them: inductively coupled ground mass spectrometry (ICP-MS), flame-induced atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (GFAAS), optical emission spectrometry with excitation in inductively coupled plasma (ICP-OES), X-ray fluorescence spectrometry (XRF), and neutron activation analysis (NAA). Additionally, we present a summary of concentration values found by different research groups.

Effect of manganese on neural endocrine hormones in serum of welders and smelters

BACKGROUND

Although manganese (Mn)-induced neurotoxicity effects are well known among occupational Mn exposure, few reports have investigated the effects on endocrine systems among welders and smelters.

OBJECTIVE

To determine the effect of high level occupational manganese (Mn) exposure on neuropsychological parameters and hormonal status.

METHODS

We used a cross-sectional design with 52 welders, 48 smelters and 43 age-matched office workers from the same factory in China. We analyzed serum endocrine hormones level and airborne Mn concentrations. Erythrocyte and urine Mn levels were quantified using inductively-coupled plasma atomic emission spectroscopy.

RESULTS

The geometric mean of air Mn concentrations for the welders and smelters were 19.7 and 273.1 μg/m³, respectively. Mn concentrations in erythrocytes of smelters were markedly greater than those in controls and welders, but there was no difference between the erythrocytes Mn levels of Control and welders. We also found an increase of Mn levels in the urine of both welders and smelters vs. controls; Mn levels in urine of smelters were higher than in welders. Self-reported neurobehavioral symptoms were higher in welders and smelters than in controls. Finally, thyroid-stimulating hormone (TSH) levels of welders were significantly lower than in controls, whereas smelters had lower prolactin (PRL), testosterone (TST) and follicle-stimulating hormone (FSH) concentrations than either controls or welders.

CONCLUSIONS

These results show that smelters have higher Mn exposure than do welders, and that Mn levels in erythrocytes or urine can be a marker for exposure. Moreover, high level occupational Mn exposure increases adverse neurobehavioral effects, and also may disrupt endocrine systems.

Occupational Exposure to Manganese and Fine Motor Skills in Elderly Men: Results from the Heinz Nixdorf Recall Study

Objectives

Exposure to manganese (Mn) may cause movement disorders, but less is known whether the effects persist after the termination of exposure. This study investigated the association between former exposure to Mn and fine motor deficits in elderly men from an industrial area with steel production.

Methods

Data on the occupational history and fine motor tests were obtained from the second follow-up of the prospective Heinz Nixdorf Recall Study (2011-2014). The study population included 1232 men (median age 68 years). Mn in blood (MnB) was determined in archived samples (2000-2003). The association between Mn exposure (working as welder or in other at-risk occupations, cumulative exposure to inhalable Mn, MnB) with various motor functions (errors in line tracing, steadiness, or aiming and tapping hits) was investigated with Poisson and logistic regression, adjusted for iron status and other covariates. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated for substantially impaired dexterity (errors >90th percentile, tapping hits <10th percentile).

Results

The median of cumulative exposure to inhalable Mn was 58 µg m-3 years in 322 men who ever worked in at-risk occupations. Although we observed a partly better motor performance of exposed workers at group level, we found fewer tapping hits in men with cumulative Mn exposure >184.8 µg m-3 years (OR 2.15, 95% CI 1.17-3.94). MnB ≥ 15 µg l-1, serum ferritin ≥ 400 µg l-1, and gamma-glutamyl transferase ≥74 U l-1 were associated with a greater number of errors in line tracing.

Conclusions

We found evidence that exposure to inhalable Mn may carry a risk for dexterity deficits. Whether these deficits can be exclusively attributed to Mn remains to be elucidated, as airborne Mn is strongly correlated with iron in metal fumes, and high ferritin was also associated with errors in line tracing. Furthermore, hand training effects must be taken into account when testing for fine motor skills.

Alterations of serum macro-minerals and trace elements are associated with major depressive disorder: a case-control study

BACKGROUND

Major depressive disorder (MDD) is a mixed disorder with the highly irregular course, inconsistent response to treatment and has no well-known mechanism for the pathophysiology. Major causes of depression are genetic, neurobiological, and environmental. However, over the past few years, altered serum levels of macro-minerals (MM) and trace elements (TE) have been recognized as major causative factors to the pathogenesis of many mental disorders. The purpose of this study was to determine the serum levels of MM (calcium and magnesium) and TE (copper, iron, manganese, selenium, and zinc) in MDD patients and find out their associations with depression risk.

METHODS

This prospective case-control study recruited 247 patients and 248 healthy volunteers matched by age and sex. The serum levels of MM and TE were analyzed by atomic absorption spectroscopy (AAS). Statistical analysis was performed with independent sample t-tests and Pearson's correlation test.

RESULTS

We found significantly decreased concentrations of calcium and magnesium, iron, manganese, selenium, and zinc in MDD patients compared with control subjects (p < 0.05). But the concentration of copper was significantly increased in the patients than control subjects (p < 0.05). Data obtained from different inter-element relations in MDD patients and control subjects strongly suggest that there is a disturbance in the element homeostasis.

CONCLUSION

Our study suggests that altered serum concentrations of MM and TE are major contributing factors for the pathogenesis of MDD. Alterations of these elements in serum levels of MDD patients arise independently and they may provide a prognostic tool for the assessment of depression risk.

Hypermanganesemia due to mutations in SLC39A14: further insights into Mn deposition in the central nervous system

Background

The SLC39A14, SLC30A10 and SLC39A8 are considered to be key genes involved in manganese (Mn) homeostasis in humans. Mn levels in plasma and urine are useful tools for early recognition of these disorders. We aimed to explore further biomarkers of Mn deposition in the central nervous system in two siblings presenting with acute dystonia and hypermanganesemia due to mutations in SLC39A14. These biomarkers may help clinicians to establish faster and accurate diagnosis and to monitor disease progression after chelation therapy is administered.

Results

A customized gene panel for movement disorders revealed a novel missense variant (c.311G > T; p.Ser104Ile) in SLC39A14 gene in two siblings presenting at the age of 10 months with acute dystonia and motor regression. Mn concentrations were analyzed using inductively coupled mass spectrometry in plasma and cerebrospinal fluid, disclosing elevated Mn levels in the index case compared to control patients. Surprisingly, Mn values were 3-fold higher in CSF than in plasma. We quantified the pallidal index, defined as the ratio between the signal intensity in the globus pallidus and the subcortical frontal white matter in axial T1-weighted MRI, and found significantly higher values in the SLC39A14 patient than in controls. These values increased over a period of 10 years, suggesting the relentless pallidal accumulation of Mn. Following genetic confirmation, a trial with the Mn chelator Na₂CaEDTA led to a reduction in plasma Mn, zinc and selenium levels. However, parents reported worsening of cervical dystonia, irritability and sleep difficulties and chelation therapy was discontinued.

Conclusions

Our study expands the very few descriptions of patients with SLC39A14 mutations. We report for the first time the elevation of Mn in CSF of SLC39A14 mutated patients, supporting the hypothesis that brain is an important organ of Mn deposition in SLC39A14-related disease. The pallidal index is an indirect and non-invasive method that can be used to rate disease progression on follow-up MRIs. Finally, we propose that patients with inherited defects of manganese transport should be initially treated with low doses of Na₂CaEDTA followed by gradual dose escalation, together with a close monitoring of blood trace elements in order to avoid side effects.

Mitochondrial dysfunction is responsible for fatty acid synthase inhibition-induced apoptosis in breast cancer cells by PdpaMn

Targeting cellular metabolism is becoming a hallmark to overcome drug resistance in breast cancer treatment. Activation of fatty acid synthase (FASN) has been shown to promote breast cancer cell growth. However, there is no concrete report underlying the mechanism associated with mitochondrial dysfunction in relation to fatty acid synthase inhibition-induced apoptosis in breast cancer cells. The current study is aimed at exploring the effect of the novel manganese (Mn) complex, labeled as PdpaMn, on lipid metabolism and mitochondrial function in breast cancer cells. Herein, we observed that PdpaMn displayed strong cytotoxicity on breast cancer cell lines and selectively targeted the tumor without affecting the normal organs or cells in vivo. We also observed that PdpaMn could bind to TE domain of FASN and decrease the activity and the level of expression of FASN, which is an indication that FASN could serve as a target of PdpaMn. In addition, we demonstrated that PdpaMn increased intrinsic apoptosis in breast cancer cells relayed by a suppressed the level of expression of FASN, followed by the release of mitochondrial cytochrome c and the activation of caspases-9. Instigated by the above observations, we hypothesized that PdpaMn-induced apoptosis events are dependent on mitochondrial dysfunction. Indeed, we found that mitochondrial membrane potential (MMP) collapse, mitochondrial oxygen consumption reduction and adenosine triphosphate (ATP) release were deeply repressed. Furthermore, our results showed that PdpaMn significantly increased the reactive oxygen species (ROS) production, and the protection conferred by the free radical scavenger N-acetyl-cysteine (NAC) indicates that PdpaMn-induced apoptosis through an oxidative stress-associated mechanism. More so, the above results have demonstrated that mitochondrial dysfunction participated in FASN inhibition-induce apoptosis in breast cancer cells by PdpaMn. Therefore, PdpaMn may be considered as a good candidate for anti-breast cancer therapeutic option.

Sodium P-aminosalicylic acid inhibits sub-chronic manganese-induced neuroinflammation in rats by modulating MAPK and COX-2

Excessive manganese (Mn) accumulation in the brain may induce an extrapyramidal disorder known as manganism. Inflammatory processes play a critical role in neurodegenerative diseases. Therapeutically, non-steroidal anti-inflammatory drugs or analogous anti-inflammatory therapies have neuroprotective effects. As a non-steroidal anti-inflammatory drug, p-aminosalicylic acid (PAS) has anti-inflammatory effects, which are mediated by decreased prostaglandins E2 (PGE2) levels. The aim of the current study was to investigate whether PAS-Na treatment prevents Mn-induced behavioral changes and neuroinflammation in vivo. Male Sprague-Dawley rats were intraperitoneally (i.p.) injected with MnCl₂·4H₂O (15mg/kg) for 12 weeks, followed by 6 weeks PAS-Na treatment. Sub-chronic Mn exposure increased Mn levels in the whole blood, cortex, hippocampus and thalamus, and induced learning and memory deficits, concomitant with astrocytes activation in the cortex, hippocampus and thalamus. Moreover inflammatory cytokine levels in serum and brain of Mn-treated group were increased, including IL-1β, IL-6, TNF-αand PGE2, especially in the hippocampus and thalamus. Furthermore, sub-chronic Mn exposure also increased inflammatory cytokines and COX-2 in transcription levels concomitant with increased MAPK signaling and COX-2 in the same selected brain regions. PAS-Na treatment at the highest doses also decreased Mn levels in the whole blood and selected brain tissues, and reversed the Mn-induced learning and memory deficits. PAS-Na inhibited astrocyte activation as well as the Mn-induced increase in inflammatory cytokine levels, reducing p38, ERK MAPK pathway and COX-2 activity. In contrast PAS-Na had no effects on the JNK MAPK pathway. These data establish the efficacy of PAS-Na not only as a chelating agent to mobilize whole blood Mn, but also as an anti-inflammatory agent.

Association of Serum Manganese Levels with Alzheimer's Disease and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

Manganese (Mn) is one of the most studied environmental heavy metals linked to Alzheimer’s disease (AD). However, it remains unclear whether serum Mn levels are associated with AD and mild cognition impairment (MCI, a prodromal stage of AD). We conducted a meta-analysis to analyze the serum Mn levels in patients with AD and MCI. A systematic database search of PubMed, Web of Science, and the China National Knowledge Infrastructure (CNKI) identified 17 studies, including 836 cases and 1254 health controls (HC). Random-effects meta-analysis showed that patients with AD had significantly reduced serum Mn levels compared with HC subjects (SMD = −0.39; 95% CI (−0.71, −0.08); p = 0.015). MCI individuals had a tendency toward reduced serum Mn levels compared with HC subjects (SMD = −0.31; 95% CI (−0.70, 0.08); p = 0.117). A significant decrease in serum Mn levels was found in patients with cognitive impairment (including both AD patients and MCI patients) (SMD = −0.37, 95% CI (−0.60; −0.13); p = 0.002). Finally, no significant differences were observed between AD and MCI patients in serum levels (SMD = 0.24; 95% CI (−0.23, 0.72); p = 0.310). Our findings show that the serum Mn levels are lower in AD patients, and Mn deficiency may be a risk factor for AD.

A novel manganese complex selectively induces malignant glioma cell death by targeting mitochondria

Despite advances in treatment, malignant glioma commonly exhibits recurrence, subsequently leading to a poor prognosis. As manganese (Mn) compounds can be transported by the transferrin-transferrin receptor system, the present study synthesized and examined the potential use of Adpa-Mn as a novel antitumor agent. Adpa-Mn time and dose-dependently inhibited U251 and C6 cell proliferation; however, it had little effect on normal astrocytes. Apoptosis was significantly elevated following treatment with Adpa-Mn, as detected by chromatin condensation, Annexin V/propidium iodide staining, cytochrome c release from mitochondria to the cytoplasm, and the activation of caspases-9, -7 and -3 and poly (ADP-ribose) polymerase. In addition, Adpa-Mn enhanced fluorescence intensity of monodansylcadaverine and elevated the expression levels of the autophagy-related protein microtubule-associated protein 1 light chain 3. Pretreatment with the autophagy inhibitors 3-methyladenine and chloroquine enhanced Adpa-Mn-induced cell inhibition, thus indicating that autophagy has an essential role in this process. Furthermore, evidence of mitochondrial dysfunction was detected in the Adpa-Mn-treated group, including disrupted membrane potential, elevated levels of reactive oxygen species (ROS) and depleted adenosine triphosphate. Conversely, treatment with the mitochondrial permeability transition inhibitor cyclosporin A reversed Adpa-Mn-induced ROS production, mitochondrial damage and cell apoptosis, thus suggesting that Adpa-Mn may target the mitochondria. Taken together, these data suggested that Adpa-Mn may be considered for use as a novel anti-glioma therapeutic option.

Altered metal metabolism in patients with HCV-related cirrhosis and hepatic encephalopathy

Dysfunctional metal homeostasis contributes to oxidative stress and neuronal damage. These have been implicated in hepatic encephalopathy pathogenesis. To investigate whether altered metal metabolism is associated with hepatic encephalopathy. Twenty-one controls and 34 HCV-cirrhotic patients (ENC/NEC patients according to presence/absence of previous overt episodes of hepatic encephalopathy) and a control group were studied. Serum iron, copper, ceruloplasmin, ceruloplasmin activity, transferrin, and ceruloplasmin/transferrin ratio were determined. Neuropsychological tests were performed by the repeatable battery of neuropsychological status. Magnetic resonance assessed basal ganglia volumes and metal deposition (pallidal index and T2*). Cirrhotic patients performed worse than controls at cognitive tests, especially ENC patients,. At biochemical analysis copper concentrations, ceruloplasmin activity and transferrin levels were lower in ENC than in NEC patients and controls (p < 0.05 and p < 0.01, respectively). Ceruloplasmin/transferrin ratio was higher in ENC compared to NEC patients (p < 0.05), and controls (p < 0.01). By brain magnetic resonance, ENC patients showed reduced caudate and globus pallidus volumes compared to controls (p < 0.05), and ENC and NEC patients an increased pallidal index compared to controls (p < 0.01). In ENC patients, ceruloplasmin activity correlated with caudate volume and pallidal index (ρ = 0.773 and ρ = -0.683, p < 0.05). Altered metal metabolism likely contributes to cirrhotic hepatic encephalopathy.