Metallomics Applied to the Study of Neurodegenerative and Mental Diseases

Multivariate Assessment of Lipoxidative Metabolites, Trace Biometals, and Antioxidant and Detoxifying Activities in the Cerebrospinal Fluid Define a Fingerprint of Preclinical Stages of Alzheimer’s Disease

Background: There exists considerable interest in the identification of molecular traits during early stages of Alzheimer’s disease (AD). Mild cognitive impairment (MCI) is considered the closest prodromal stage of AD, and to develop gradually from earlier stages although not always progresses to AD. Classical cerebrospinal fluid (CSF) AD biomarkers, amyloid-β peptides and tau/p-tau proteins, have been measured in prodromal stages yet results are heterogeneous and far from conclusive. Therefore, there exists a pressing need to identify a neurochemical signature for prodromal stages and to predict which cases might progress to AD. Objective: Exploring potential CSF biomarkers related to brain oxidative and inorganic biochemistry during prodromal stages of the disease. Methods: We have analyzed CSF levels of lipoxidative markers (MDA and 8-isoF2α), biometals (Cu, Zn, Se, Mn, and Fe), iron-transport protein transferrin (TFER), antioxidant enzymes (SOD and GPx4), detoxifying enzymes (GST and BuChE), as well as classical amyloid-β and total and phosphorylated tau, in cognitively healthy controls, patients with MCI, and subjects exhibiting subjective memory complaints (SMC). Results: Inter-group differences for several variables exhibit differentiable trends along the HC ⟶ SMC ⟶ MCI sequence. More interestingly, the combination of Se, Cu, Zn, SOD, TFER, and GST variables allow differentiable fingerprints for control subjects and each prodromal stage. Further, multivariate scores correlate positively with neurocognitive In-Out test, hence with both episodic memory decline and prediction to dementia. Conclusion: We conclude that changes in the CSF biochemistry related to brain oxidative defense and neurometallomics might provide more powerful and accurate diagnostic tools in preclinical stages of AD.

Exposure to e-cigarette aerosol over two months induces accumulation of neurotoxic metals and alteration of essential metals in mouse brain

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

Unravelling neurological disorders through metallomics-based approaches

Understanding the biological process involving metals and biomolecules in the brain is essential for establishing the origin of neurological disorders, such as neurodegenerative and psychiatric diseases. From this perspective, this critical review presents recent advances in this topic, showing possible mechanisms involving the disruption of metal homeostasis and the pathogenesis of neurological disorders. We also discuss the main challenges observed in metallomics studies associated with neurological disorders, including those related to sample preparation and analyte quantification.

Understanding the relationship between viral infections and trace elements from a metallomics perspective: implications for COVID-19

Recently, the World Health Organization (WHO) declared a pandemic situation due to a new viral infection (COVID-19) caused by a novel virus (Sars-CoV-2). COVID-19 is today the leading cause of death from viral infections in the world. It is known that many elements play important roles in viral infections, both in virus survival, and in the activation of the host's immune system, which depends on the presence of micronutrients to maintain the integrity of its functions. In this sense, the metallome can be an important object of study for understanding viral infections. Therefore, this work presents an overview of the role of trace elements in the immune system and the state of the art in metallomics, highlighting the challenges found in studies focusing on viral infections.

Disease Ionomics: Understanding the Role of Ions in Complex Disease

Ionomics is a novel multidisciplinary field that uses advanced techniques to investigate the composition and distribution of all minerals and trace elements in a living organism and their variations under diverse physiological and pathological conditions. It involves both high-throughput elemental profiling technologies and bioinformatic methods, providing opportunities to study the molecular mechanism underlying the metabolism, homeostasis, and cross-talk of these elements. While much effort has been made in exploring the ionomic traits relating to plant physiology and nutrition, the use of ionomics in the research of serious diseases is still in progress. In recent years, a number of ionomic studies have been carried out for a variety of complex diseases, which offer theoretical and practical insights into the etiology, early diagnosis, prognosis, and therapy of them. This review aims to give an overview of recent applications of ionomics in the study of complex diseases and discuss the latest advances and future trends in this area. Overall, disease ionomics may provide substantial information for systematic understanding of the properties of the elements and the dynamic network of elements involved in the onset and development of diseases.

Neurodevelopmental disorders: Metallomics studies for the identification of potential biomarkers associated to diagnosis and treatment

BACKGROUND

Diagnosis and treatment of complex diseases such as Neurodevelopmental Disorders (NDDs) can be resolved through the identification of biomarkers. Metallomics (research on biometals) and metallomes (metalloproteins/metalloenzymes/chaperones) along with genomics, proteomics and metabolomics, can contribute to accelerate and improve this process.

AIM

This review focused on four NDDs pathologies (Schizophrenia, SZ; Attention Deficit Hyperactivity Disorder, ADHD; Autism, ADS; Epilepsy), and we reported, for the first time, different studies on the role played by the principal six essential trace elements (Cobalt, Co; Copper, Cu; Iron, Fe; Manganese, Mn; Selenium, Se; Zinc, Zn) that can influence diagnosis/treatment.

RESULTS

in light of the literature presented, based on meta-analyses, we suggest that Zn (glutamatergic neurotransmission, inflammation, neurodegeneration, autoimmunity alterations), could be a potential diagnostic biomarker associated to SZ. Moreover, considering the single association studies going in the same direction, increased Cu (catecholamine alterations, glucose intolerance, altered lipid metabolism/oxidative stress) and lower Fe (dopaminergic dysfunctions) levels were associated with a specific negative symptomatology. Lower Mn (lipid metabolism/oxidative stress alterations), and lower Se (metabolic syndrome) were linked to SZ. From the meta-analyses in ADHD, it is evidenced that Fe (and ferritin in particular), Mn, and Zn (oxidative stress dysfunctions) could be potential diagnostic biomarkers, mainly associated to severe hyperactive or inattentive symptoms; as well as Cu, Fe, Zn in ADS and Zn in Epilepsy. Fe, Zn and Mn levels seem to be influenced by antipsychotics treatment in SZ; Mn and Zn by methylphenidate treatment in ADHD; Cu and Zn by antiepileptic drugs in Epilepsy.

CONCLUSIONS

Although there is controversy and further studies are needed, this work summarizes the state of art of the literature on this topic. We claim to avoid underreporting the impact of essential trace elements in paving the way for biomarkers research for NDDs.

Association between trace elements in serum from bipolar disorder and schizophrenia patients considering treatment effects

BACKGROUND

Imbalances in metal concentrations have been suggested to contribute to the pathophysiology of different brain disorders, such as bipolar disorder (BD) and schizophrenia (SCZ).

OBJECTIVES

The aim of this exploratory study is to evaluate the association between the concentrations of macro/trace elements in serum from BD and SCZ patients considering the effects from different treatments.

METHODS

Eleven subjects with SCZ, seven with BD treated with lithium (BDL) and eight subjects with BD treated with other medications except lithium (BDN) were recruited for the study, as well as eleven healthy controls (HC). Serum concentrations of eleven macro/trace elements (Se, Zn, Fe, K, Ca, Mg, P, Al, Cu, Mn, and Ni) were determined using inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Se and Zn concentrations were significantly lower for patients with SCZ and BD in comparison to HC by one-way ANOVA test. Moreover, serum concentrations for Fe were significantly higher (p < 0.05) in BDN (548 ± 92 μg L^-1) and SCZ (632 ± 279 μg L^-1) in comparison to HC (421 ± 121 μg L^-1). A significant negative correlation was reported between Se and Fe in BDL group (r = -0.935, p < 0.05). In addition, a significantly higher Cu/Zn ratio was determined in SCZ group against HC (ratio = 2.4, p = 0.028).

CONCLUSIONS

The obtained results suggest that the imbalance in Fe concentrations is an effect of BD treatment. Lithium is supposed to have an antagonist effect for Se in BDL patients. A negative correlation reported between Fe and BMI in SCZ group could be related to antipsychotic treatment and the Cu/Zn ratio reported could be considered as a suggesting parameter to relate oxidative stress to SCZ. Future studies including larger number of patients with SCZ and BD before and after treatment are necessary to confirm the investigative results presented herein.