Human exposure to aluminium

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Evaluation of Aluminum and Magnesium Absorption Following the Oral Administration of an Antacid Suspension Containing Magaldrate in Healthy Women Under Fed Conditions

INTRODUCTION

Antacids are commonly used during pregnancy, and they are approved for the relief of symptoms of gastroesophageal reflux disease (GERD) during pregnancy. However, there are no reports of the quantification of the absorption of aluminum and magnesium in the antacid magaldrate in women. The aim of this study was to quantify the rate and magnitude of absorption of aluminum and magnesium in magaldrate.

METHODS

An open-label, controlled, randomized, one-treatment study with a two-group design was conducted in healthy women in a fed state. The volunteers had a standard breakfast, and 30 min later, they were given a single-medication sachet containing 500 mg of sodium alginate, 267 mg of sodium bicarbonate, 800 mg of magaldrate, and 120 mg of simethicone (group A, n = 8) or no medication (group B, n = 2). Blood samples were obtained 36 h before and up to 12 h after antacid administration. The method used for quantification was inductively coupled plasma-mass spectrometry.

RESULTS

There was no absorption of aluminum in any of the blood samples from the healthy volunteers who received the drug or in those from the control group. Magnesium was detected at normal concentrations.

CONCLUSION

These findings suggest that the use of this antacid is safe and without risk in healthy women, including pregnant women.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov registration: NCT06367452.

Metal Toxicity and Dementia Including Frontotemporal Dementia: Current State of Knowledge

Frontotemporal dementia (FTD) includes a number of neurodegenerative diseases, often with early onset (before 65 years old), characterized by progressive, irreversible deficits in behavioral, linguistic, and executive functions, which are often difficult to diagnose due to their similar phenotypic characteristics to other dementias and psychiatric disorders. The genetic contribution is of utmost importance, although environmental risk factors also play a role in its pathophysiology. In fact, some metals are known to produce free radicals, which, accumulating in the brain over time, can induce oxidative stress, inflammation, and protein misfolding, all of these being key features of FTD and similar conditions. Therefore, the present review aims to summarize the current evidence about the environmental contribution to FTD-mainly dealing with toxic metal exposure-since the identification of such potential environmental risk factors can lead to its early diagnosis and the promotion of policies and interventions. This would allow us, by reducing exposure to these pollutants, to potentially affect society at large in a positive manner, decreasing the burden of FTD and similar conditions on affected individuals and society overall. Future perspectives, including the application of Artificial Intelligence principles to the field, with related evidence found so far, are also introduced.

Epigenetic Mechanisms of Aluminum-Induced Neurotoxicity and Alzheimer's Disease: A Focus on Non-Coding RNAs

Aluminum (Al) is known to induce neurotoxic effects, potentially contributing to Alzheimer's disease (AD) pathogenesis. Recent studies suggest that epigenetic modification may contribute to Al neurotoxicity, although the mechanisms are still debatable. Therefore, the objective of the present study was to summarize existing data on the involvement of epigenetic mechanisms in Al-induced neurotoxicity, especially AD-type pathology. Existing data demonstrate that Al exposure induces disruption in DNA methylation, histone modifications, and non-coding RNA expression in brains. Alterations in DNA methylation following Al exposure were shown to be mediated by changes in expression and activity of DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs). Al exposure was shown to reduce histone acetylation by up-regulating expression of histone deacetylases (HDACs) and impair histone methylation, ultimately contributing to down-regulation of brain-derived neurotrophic factor (BDNF) expression and activation of nuclear factor κB (NF-κB) signaling. Neurotoxic effects of Al exposure were also associated with aberrant expression of non-coding RNAs, especially microRNAs (miR). Al-induced patterns of miR expression were involved in development of AD-type pathology by increasing amyloid β (Aβ) production through up-regulation of Aβ precursor protein (APP) and β secretase (BACE1) expression (down-regulation of miR-29a/b, miR-101, miR-124, and Let-7c expression), increasing in neuroinflammation through NF-κB signaling (up-regulation of miR-9, miR-125b, miR-128, and 146a), as well as modulating other signaling pathways. Furthermore, reduced global DNA methylation, altered histone modification, and aberrant miRNA expression were associated with cognitive decline in Al-exposed subjects. However, further studies are required to evaluate the contribution of epigenetic mechanisms to Al-induced neurotoxicity and/or AD development.

Mitigating aluminum toxicity and promoting plant resilience in acidic soil with Penicillium olsonii TLL1

Aluminum (Al), prevalent in the crust of the Earth, jeopardizes plant health in acidic soils, hindering root growth and overall development. In this study, we first analysed the Al- and pH- tolerance of the Penicillium olsonii TLL1 strain (POT1; NRRL:68252) and investigated the potential for enhancing plant resilience under Al-rich acidic soil conditions. Our research illustrates the extraordinary tolerance of POT1 to both high Al concentrations and acidic conditions, showcasing its potential to alleviate Al-induced stress in plants. Metabolite analysis revealed that POT1 detoxifies Al through organic acid-dependent chelation mechanisms, significantly reducing Al stress in Arabidopsis and Pak Choi plants. Consequently, plant growth conditions improved, and the Al content in plant tissues decreased. Transcriptome analysis indicated that POT1 treatment downregulates genes associated with Al and oxidative stress such as MATE, ALS3, NIP1-2 and several peroxidases, highlighting its effectiveness in lessening Al-induced damage. Comparative assessments highlight the superior performance of POT1 compared to other Al-tolerant Penicillium species, attributed to its ability to thrive in diverse pH levels and effectively detoxify Al. These findings position POT1 as a promising agent for enhancing crop resilience in Al-compromised acidic soils, offering new avenues for promoting plant health and bolstering food security through increased crop yield and safety.

Aluminum Biorecovery from Wastewaters

Aluminum biorecovery is still at an early stage. However, a significant number of studies showing promising results already exist, although they have revealed problems that need to be solved so aluminum biorecovery can have a wider application and industrial upscaling. In this chapter, we revise the existing knowledge on the biorecovery of aluminum from different sources. We discuss the design, overall performance, advantages, technical problems, limitations, and possible future directions of the different biotechnological methods that have been reported so far. Aluminum biorecovery from different sources has been studied (i.e., solid wastes and primary sources of variable origin, wastewater with low concentrations of dissolved aluminum at pH-neutral or weakly acidic conditions, and acidic mine waters with high concentrations of dissolved aluminum and other metal(loid)s) and has shown that the process efficiency strongly depends on factors such as (1) the physicochemical properties of the source materials, (2) the physiological features of the used (micro)organisms, or (3) the biochemical process used. Bioleaching of aluminum from low-grade bauxite or red mud can much be achieved by a diverse range of organisms (e.g., fungi, bacteria) with different metabolic rates. Biorecovery of aluminum from wastewaters, e.g., domestic wastewater, acidic mine water, has also been accomplished by the use of microalgae, cyanobacteria (for domestic wastewater) or by sulfate-reducing bacteria (acidic mine water). In most of the cases, the drawback of the process is the requirement of controlled conditions which involves a continuous supply of oxygen or maintenance of anoxic conditions which make aluminum biorecovery challenging in terms of process design and economical value. Further studies should focus on studying these processes in comparison or in combination to existing economical processes to assess their feasibility.

Increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress

N6-methyladenosine (m6A) RNA modification is a new epigenetic molecular mechanism involved in various biological or pathological processes. Exposure to aluminum (Al) has been considered to promote neuronal apoptosis resulting in cognitive dysfunction, yet whether m6A modification participates in the underlying mechanism remains largely unknown. Here, rats exposed to aluminum-maltolate [Al(mal)3] for 90 days showed impaired learning and memory function and elevated apoptosis, which were related to the increased m6A level and decreased fat mass and obesity-associated protein (FTO, an m6A demethylase) in the hippocampus. Accordingly, similar results presented in PC12 cells following Al(mal)3 treatment and FTO overexpression relieved the increased apoptosis and m6A level in vitro. Next, we identified brain-derived neurotrophic factor (BDNF) as the functional downstream target of FTO in a m6A-dependent manner. Furthermore, it was found that as the onset of aluminum neurotoxicity, oxidative stress may be the upstream regulator of FTO in aluminum-induced apoptosis. Taken together, these results suggest that increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress.

Central Causation of Autism/ASDs via Excessive [Ca2+]i Impacting Six Mechanisms Controlling Synaptogenesis during the Perinatal Period: The Role of Electromagnetic Fields and Chemicals and the NO/ONOO(-) Cycle, as Well as Specific Mutations

The roles of perinatal development, intracellular calcium [Ca2+]i, and synaptogenesis disruption are not novel in the autism/ASD literature. The focus on six mechanisms controlling synaptogenesis, each regulated by [Ca2+]i, and each aberrant in ASDs is novel. The model presented here predicts that autism epidemic causation involves central roles of both electromagnetic fields (EMFs) and chemicals. EMFs act via voltage-gated calcium channel (VGCC) activation and [Ca2+]i elevation. A total of 15 autism-implicated chemical classes each act to produce [Ca2+]i elevation, 12 acting via NMDA receptor activation, and three acting via other mechanisms. The chronic nature of ASDs is explained via NO/ONOO(-) vicious cycle elevation and MeCP2 epigenetic dysfunction. Genetic causation often also involves [Ca2+]i elevation or other impacts on synaptogenesis. The literature examining each of these steps is systematically examined and found to be consistent with predictions. Approaches that may be sed for ASD prevention or treatment are discussed in connection with this special issue: The current situation and prospects for children with ASDs. Such approaches include EMF, chemical avoidance, and using nutrients and other agents to raise the levels of Nrf2. An enriched environment, vitamin D, magnesium, and omega-3s in fish oil may also be helpful.

Effect of Sempervivum tectorum Extract on Some Biomarkers of Reproductive Function and Levels of Some Trace Elements in Male Rats Exposed to Aluminum

Aluminum, a contentious trace element found in the environment, has been demonstrated to have harmful effects on both humans and animals. In contrast, Sempervivum tectorum, an evergreen plant, has been found to offer numerous beneficial effects for both humans and animals. Therefore, this study aims to assess the protective effect of S. tectorum on certain reproductive biomarkers in male rats exposed to aluminum. Thirty-five Wistar rats were randomly divided into five groups: NTC (no-treatment control) received distilled water; NC (negative control) received drinking water containing 1 mg/L aluminum sulfate (AS); E1 received 1 mg/L AS along with an 8% S. tectorum extract; PC (positive control) received only 8% S. tectorum extract; E2 received 1 mg/L AS for three months followed by 8% extract for one month. The study analyzed testosterone, LH, FSH, body weight, and the histological structure of the testis, epididymis, and prostate, as well as the levels of zinc, manganese, copper, and iron in these organs. Significant decreases in body weight, testis, and epididymis size were observed in the aluminum-exposed groups compared to the control, whereas these decreases were not significant in the S. tectorum-treated groups compared to the control. Aluminum exposure led to significant decreases in testosterone and LH levels, with FSH levels showing a nonsignificant decrease in males, which were mitigated significantly by the administration of the plant extract. Histological analysis revealed alterations in the testis, epididymis, and prostate of the AS-exposed groups, including necrosis of seminiferous tubule epithelium and Leydig cells in the testis, and basal epithelial necrosis in the epididymis and prostate. Aluminum levels increased in all organs studied, while levels of zinc, copper, iron, and manganese decreased, showing a negative and significant correlation with aluminum levels. The aqueous extract of S. tectorum demonstrated a protective effect on certain studied biomarkers in male rats affected by aluminum exposure.

Evaluation of possible neuroprotective effects of virgin coconut oil on aluminum-induced neurotoxicity in an in vitro Alzheimer's disease model

Alzheimer's disease (AD) is a progressive neurological disorder that affects various cognitive functions, behavior, and personality. AD is thought to be caused by a combination of genetic and environmental factors, including exposure to aluminum (Al). Virgin coconut oil (VCO) may have potential as a natural neuroprotectant against AD. Aim of this study was to determine neuroprotective effects of VCO on Al-induced neurotoxicity in an in vitro AD model. SH-SY5Y cells were initially cultured in normal growth medium and then differentiated by reducing fetal bovine serum content and adding retinoic acid (RA). Later, brain-derived neurotrophic factor (BDNF) was added along with RA. The differentiation process was completed on the seventh day. Study groups (n = 3) were designed as control group, VCO group, Al group, Al-VCO group, Alzheimer model (AD) group, AD + Al-exposed group (AD+Al), AD + VCO applied group (AD + VCO) and AD + Al-exposed + VCO applied group (AD + Al + VCO). Specific markers of AD (hyperphosphorylated Tau protein, amyloid beta 1-40 peptide, and amyloid precursor protein) were measured in all groups. In addition, oxidative stress parameters (total antioxidant capacity, lipid peroxidase, protein carbonyl, and reactive oxygen species) and neurotransmitter-related parameters (dopamine, dopamine transporter acetylcholine, and synuclein alpha levels, acetylcholinesterase activity) were measured comparatively in the study groups. VCO reduced amyloid beta and hyperphosphorylated Tau protein levels in the study groups. In addition, oxidative stress levels decreased, and neurotransmitter parameters improved with VCO. Our study shows that VCO may have potential therapeutic effects in Alzheimer's disease and further experiments are needed to determine its efficacy.

Embryonic exposure to aluminum chloride blocks the onset of spermatogenesis through disturbing the dynamics of testicular tight junctions via upregulating Slc25a5 in offspring

Studies have revealed neurotoxicity, hepatotoxicity, and developmental and reproductive toxicity in mice exposed to aluminum. However, relatively few studies have been conducted to clarify the mechanism underlying the impact of embryonic exposure to aluminum on the development of the male reproductive system in offspring. Pregnant mice were administered aluminum chloride (AlCl3) by gavage from day 12.5 of gestation until birth. Our findings demonstrated that embryonic exposure to AlCl3 disrupted testicular development and spermatogenesis by impairing testicular architecture, reducing sperm count, and upregulating the expression of tight junction (TJ) protein between Sertoli cells (SCs). Further in vitro studies revealed that treatment with AlCl3 stabilized TJ proteins Occludin and ZO-1 expression by inhibiting ERK signaling pathway activation, thereby upregulating Slc25a5 expression which induced ATP production leading to disruption of cytoskeletal protein homeostasis. Therefore, the study provided a new mechanistic insight into how AlCl3 exposure interfered with testicular development and spermatogenesis while suggesting that Slc25a5 might be a target affected by AlCl3 influencing cell metabolism.

Nondestructive Evaluation of Metal Bioaccumulation and Biochemical Biomarkers in Blood of Broad-Snouted Caiman (Caiman latirostris) from Northeastern Brasil

Studies on the bioaccumulation and toxicity of contaminants in Crocodylians are scarce. We evaluated alterations in concentrations of the nondestructive biomarkers butyrylcholinesterase (BChE), glutathione-S-transferase (GST), superoxide dismutase (SOD), and reduced glutathione (GSH), together with bioaccumulation of the metals iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), chronium (Cr), aluminium (Al), and lead (Pb) in Caiman latirostris captured in Tapacurá Reservoir (TR; São Lourenço da Mata, Pernambuco, Brasil), in urbanized areas of Pernambuco State (UA; Brasil) and from the AME Brasil caiman farm (AF; Marechal Deodoro, Alagoas, Brasil); the latter was used as a potential reference with low levels of contamination. For metal analysis, 500 µL of blood was digested in 65% HNO3 and 30% H2 O2 . The samples were analyzed by inductively coupled plasma-optical emission spectrometry. For analysis of biomarkers, an aliquot of blood was centrifuged to obtain plasma in which biochemical assays were performed. Blood concentrations of metals analyzed in animals from AF were lower compared with TR and UA, confirming that animals from the caiman farm could be used as references with low levels of contamination. Iron, Cu, Mn, Al, and Pb exceeded toxic levels for other vertebrates in animals from TR and UA. Butyrylcholinesterase activity showed significant reduction in adults from UA and TR compared with AF. An increase in the activity of GST and GSH, in adults of TR and UA in relation to AF, was verified. Superoxide dismutase activity showed a significant reduction in adults of TR in relation to AF, and the concentrations of Cu and Mn were negatively correlated with SOD activity. Animals from UA and TR showed greater concentrations of the analyzed metals compared with reference animals, and changes in biomarkers were seen, confirming the potential of these nondestructive chemical and biological parameters in blood of C. latirostris for biomonitoring of pollution. Environ Toxicol Chem 2024;00:1-18. © 2024 SETAC.

Pharmacodynamic, pharmacokinetic, toxicity, and recent advances in Eugenol's potential benefits against natural and chemical noxious agents: A mechanistic review

The active biological phytochemicals, crucial compounds employed in creating hundreds of medications, are derived from valuable and medicinally significant plants. These phytochemicals offer excellent protection from various illnesses, including inflammatory disorders and chronic conditions caused by oxidative stress. A phenolic monoterpenoid known as eugenol (EUG), it is typically found in the essential oils of many plant species from the Myristicaceae, Myrtaceae, Lamiaceae, and Lauraceae families. One of the main ingredients of clove oil (Syzygium aromaticum (L.), Myrtaceae), it has several applications in industry, including flavoring food, pharmaceutics, dentistry, agriculture, and cosmeceuticals. Due to its excellent potential for avoiding many chronic illnesses, it has lately attracted attention. EUG has been classified as a nonmutant, generally acknowledged as a safe (GRAS) chemical by the World Health Organization (WHO). According to the existing research, EUG possesses notable anti-inflammatory, antioxidant, analgesic, antibacterial, antispasmodic, and apoptosis-promoting properties, which have lately gained attention for its ability to control chronic inflammation, oxidative stress, and mitochondrial malfunction and dramatically impact human wellness. The purpose of this review is to evaluate the scientific evidence from the most significant research studies that have been published regarding the protective role and detoxifying effects of EUG against a wide range of toxins, including biological and chemical toxins, as well as different drugs and pesticides that produce a variety of toxicities, throughout view of the possible advantages of EUG.

A review of the epidemiological and laboratory evidence of the role of aluminum exposure in pathogenesis of cardiovascular diseases

The objective of the present study was to review the epidemiological and laboratory evidence on the role of aluminum (Al) exposure in the pathogenesis of cardiovascular diseases. Epidemiological data demonstrated an increased incidence of cardiovascular diseases (CVD), including hypertension and atherosclerosis in occupationally exposed subjects and hemodialysis patients. In addition, Al body burden was found to be elevated in patients with coronary heart disease, hypertension, and dyslipidemia. Laboratory studies demonstrated that Al exposure induced significant ultrastructural damage in the heart, resulting in electrocardiogram alterations in association with cardiomyocyte necrosis and apoptosis, inflammation, oxidative stress, inflammation, and mitochondrial dysfunction. In agreement with the epidemiological findings, laboratory data demonstrated dyslipidemia upon Al exposure, resulting from impaired hepatic lipid catabolism, as well as promotion of low-density lipoprotein oxidation. Al was also shown to inhibit paraoxonase 1 activity and to induce endothelial dysfunction and adhesion molecule expression, further promoting atherogenesis. The role of Al in hypertension was shown to be mediated by up-regulation of NADPH-oxidase, inhibition of nitric oxide bioavailability, and stimulation of renin-angiotensin-aldosterone system. It has been also demonstrated that Al exposure targets cerebral vasculature, which may be considered a link between Al exposure and cerebrovascular diseases. Findings from other tissues lend support that ferroptosis, pyroptosis, endoplasmic reticulum stress, and modulation of gut microbiome and metabolome are involved in the development of CVD upon Al exposure. A better understanding of the role of the cardiovascular system as a target for Al toxicity will be useful for risk assessment and the development of treatment and prevention strategies.

Aluminum Concentrations in Breast Milk Samples Obtained from Breastfeeding Women from a Resource-Limited Country: A Study of the Predicting Factors

This study assessed aluminum concentrations in breast milk samples obtained from breastfeeding women in resource-limited countries, estimated daily intake of aluminum by breastfed infants, and identified predictors of higher breast milk aluminum concentrations. A descriptive analytical approach was used in this multicenter study. Breastfeeding women were recruited from different maternity health clinics in Palestine. Aluminum concentrations in 246 breast milk samples were determined using an inductively coupled plasma-mass spectrometric method. The mean breast milk aluminum concentration was 2.1 ± 1.5 mg/L. The mean estimated daily intake of aluminum by infants was 0.37 ± 0.26 mg/kg body weight/day. Multiple linear regression showed that breast milk aluminum concentrations were predicted by living in urban areas, closer to industrial areas, waste disposals, frequent use of deodorants, and less frequent use of vitamins. Breast milk aluminum levels among Palestinian breastfeeding women were comparable to those previously determined in occupationally unexposed women.

Aluminum Concentrations in Male and Female Football Players during the Season

Aluminum (Al) is one of the most abundant trace mineral elements in the earth's crust. Al is considered a potent neurotoxicant. Physical exercise could cause modifications in some trace mineral elements. On the other hand, there could be sex differences in the exposure and deposits of toxic mineral elements. The aim of the present study was to compare sex and seasonal differences in extracellular and intracellular Al concentrations in football players. The study involved 22 male and 24 female football players from the fifth and second national category, respectively. Three assessments were carried out during the season (beginning, middle and end). Al concentrations in plasma, urine, erythrocytes and platelets were determined. Male football players ingested more Al (p < 0.05). Higher plasma Al concentrations were reported in male football players (p < 0.01). On the other hand, in both groups, increases and decreases in Al in the plasma and urine were observed in the second and third assessment, respectively (p < 0.01). There were sex differences in platelet Al concentrations (p < 0.05). Plasma and platelet Al concentrations may be different between the sexes. Al concentrations may change over the course of a season in football players.

Chronic Oral Administration of Aluminum Hydroxide Stimulates Systemic Inflammation and Redox Imbalance in BALB/c Mice

The present study is aimed at investigating the long-term effects of the aluminum hydroxide administration in the small intestine, lung, liver, and kidney of male BALB/c mice. The mice received via orogastric gavage phosphate buffered or 10 mg/kg aluminum hydroxide 3 times a week for 6 months. Administration of aluminum hydroxide decreased hemoglobin, hematocrit, and erythrocyte. In the blood, kidney and liver function markers were evaluated, and long-term administration of aluminum hydroxide led to an increase in AST levels and a decrease in urea levels. The animals exposed to aluminum showed higher lipid and protein oxidation in all the organs analyzed. In relation to the enzymes involved in antioxidant defense, the lungs showed lower superoxide dismutase (SOD) and catalase activity and a lower reduced and oxidized glutathione (GSH/GSSG) ratio. In the liver, aluminum administration led to a decrease in catalase activity and the GSH/GSSG ratio. Lower catalase activity was observed in the small intestine, as well as in the lungs and liver. In addition to alterations in antioxidant defense, increased levels of the chemokine CCL-2 were observed in the lungs, lower levels of IL-10 in the liver and small intestine, and decreased levels of IL-6 in the intestine of the animals that received aluminum hydroxide for 6 months. Long-term exposure to aluminum promoted steatosis in the liver. In the kidneys, mice treated with aluminum presented a decreased glomerular density than in the naive control group. In the small intestine, exposure caused villi shortening. Our results indicate that long-term oral administration of aluminum hydroxide provokes systemic histological damage, inflammation, and redox imbalance.

Neurodegenerative Proteinopathies Induced by Environmental Pollutants: Heat Shock Proteins and Proteasome as Promising Therapeutic Tools

Environmental pollutants' (EPs) amount and diversity have increased in recent years due to anthropogenic activity. Several neurodegenerative diseases (NDs) are theorized to be related to EPs, as their incidence has increased in a similar way to human EPs exposure and they reproduce the main ND hallmarks. EPs induce several neurotoxic effects, including accumulation and gradual deposition of misfolded toxic proteins, producing neuronal malfunction and cell death. Cells possess different mechanisms to eliminate these toxic proteins, including heat shock proteins (HSPs) and the proteasome system. The accumulation and deleterious effects of toxic proteins are induced through HSPs and disruption of proteasome proteins' homeostatic function by exposure to EPs. A therapeutic approach has been proposed to reduce accumulation of toxic proteins through treatment with recombinant HSPs/proteasome or the use of compounds that increase their expression or activity. Our aim is to review the current literature on NDs related to EP exposure and their relationship with the disruption of the proteasome system and HSPs, as well as to discuss the toxic effects of dysfunction of HSPs and proteasome and the contradictory effects described in the literature. Lastly, we cover the therapeutic use of developed drugs and recombinant proteasome/HSPs to eliminate toxic proteins and prevent/treat EP-induced neurodegeneration.

The postulated innocuity of lifetime exposure to aluminium should be reappraised

Because of its chemical versatility and abundance in nature, aluminium is employed in a myriad of frequently used products - including cosmetics and food additives - and applications - drinking water purification procedures being an example. Despite what its widespread use might suggest, aluminium's harmlessness is a matter of debate in the scientific community. In this article we trace the lines of a growing questioning about the potential mutagenic effects of this metal, due to the data produced over the recent years, and with an eye to the discussions currently underway in this regard between the scientific community, industry, and regulatory bodies.

Assessing Leaching of Potentially Hazardous Elements from Cookware during Cooking: A Serious Public Health Concern

The intake of toxic metals from cooking utensils through food is of growing concern to the medical community. This intake poses serious risk to human health. In many developing countries, different types of contaminated metals scraps are used to make cooking utensils. The leaching of both nutritionally essential and toxic metals in significant quantities from cookware during the cooking process results in food contamination and poses a substantial health risk. In the present study, the leaching of some toxic and potentially toxic metals from cooking utensils into different solutions and food was investigated. A preliminary survey indicated that the majority of individuals tend to use aluminum cookware due to its affordability, overlooking the potential health risks associated with these inexpensive and lower-quality cooking utensils. XRF analysis revealed that aluminum, steel, and copper cookware had K, Ca, Pb, Cd, Ni, V, Sn Mo, Zn, Bi, and Tb as contaminants. In addition, aluminum (3.2 ± 0.25 to 4.64 ± 0.20 g/kg) and copper cookware (2.90 ± 0.12 g/kg) were highly contaminated with lead. The time and pH-dependent study revealed that leaching of metals (Al, Pb, Ni, Cr, Cd, Cu, and Fe, etc.) into food was predominantly from anodized and non-anodized aluminum cookware. More metal leaching was observed from new aluminum cookware compared to old. Acidic food was found to cause more metals to leach during cooking. Blood metal analysis of the local population revealed the presence of high concentrations of Al, Pb, Cd, and Ni. In conclusion, leaching of toxic or potentially toxic metals from cookware into food, especially from anodized and non-anodized aluminum cookware, poses a potential public health risk. Practical applications: Cooking utensils are routinely used for the preparation of food. However, the harmful impact posed by these essential items is largely unknown. The current research briefly explains the toxic metals leaching from cookware in a pH-dependent manner and leaves a message to the public, especially in developing countries like Pakistan, regarding the type of cookware suitable for cooking purposes.

Recent insights into autophagy and metals/nanoparticles exposure

Some anthropogenic pollutants, such as heavy metals and nanoparticles (NPs), are widely distributed and a major threat to environmental safety and public health. In particular, lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and mercury (Hg) have systemic toxicity even at extremely low concentrations, so they are listed as priority metals in relation to their significant public health burden. Aluminum (Al) is also toxic to multiple organs and is linked to Alzheimer's disease. As the utilization of many metal nanoparticles (MNPs) gradually gain traction in industrial and medical applications, they are increasingly being investigated to address potential toxicity by impairing certain biological barriers. The dominant toxic mechanism of these metals and MNPs is the induction of oxidative stress, which subsequently triggers lipid peroxidation, protein modification, and DNA damage. Notably, a growing body of research has revealed the linkage between dysregulated autophagy and some diseases, including neurodegenerative diseases and cancers. Among them, some metals or metal mixtures can act as environmental stimuli and disturb basal autophagic activity, which has an underlying adverse health effect. Some studies also revealed that specific autophagy inhibitors or activators could modify the abnormal autophagic flux attributed to continuous exposure to metals. In this review, we have gathered recent data about the contribution of the autophagy/mitophagy mediated toxic effects and focused on the involvement of some key regulatory factors of autophagic signaling during exposure to selected metals, metal mixtures, as well as MNPs in the real world. Besides this, we summarized the potential significance of interactions between autophagy and excessive reactive oxygen species (ROS)-mediated oxidative damage in the regulation of cell survival response to metals/NPs. A critical view is given on the application of autophagy activators/inhibitors to modulate the systematic toxicity of various metals/MNPs.

Correlation between daily life aluminium exposure and breast cancer risk: A systematic review

BACKGROUND

Epidemiological data indicate that the role of environmental factors on breast cancer (BC) incidence remains undetermined. Our daily life exposure to aluminium (Al) is suspected to influence BC development. This review proposes a state of the art on the association between Al and BC risk combined with a critical point of view on the subject.

METHODS

We searched the PubMed database using terms related to Al and BC up to November 18, 2022. Reports were eligible if they were cohort or case-control studies or meta-analyses.

FINDINGS

Six studies focused on the relationship between deodorant and antiperspirant use and BC incidence and didn't produce consistent results. Among 13 studies relating Al content in mammary tissues and BC risk, results are not unanimous to validate higher Al content in tumor tissues compared to healthy ones. We detail parameters that could explain this conclusion: the absence of statistical adjustments on BC risk factors in studies, the confusion between deodorant and antiperspirant terms, the non-assessment of global Al exposure, and the focus on Al in mammary tissues whereas a profile of several metals seems more appropriate. The clinical studies are retrospective. They were carried out on small cohorts and without a long follow-up. On the other hand, studies on cell lines have shown the carcinogenic potential of aluminum. Moreover, studies considered BC as a unique group whereas BC is a heterogeneous disease with multiple tumor subtypes determining the tumor aggressiveness.

CONCLUSION

In light of the precautionary principle and based on the data obtained, it is better to avoid antiperspirants that contain Al. Deodorants without aluminum are not implicated in breast cancer, either clinically or fundamentally.

Clinical Outcomes of the Deleterious Effects of Aluminum on Neuro-Cognition, Inflammation, and Health: A Review

Introduction: In the scenario of metal toxicity, aluminum (Al) stands out as a ubiquitous type of metal that can be combined with other elements and form different compounds. Al is widely used daily as an adjuvant in vaccines, antacids, food additives (as components of AI-containing food additives), skin care products, cosmetics, and kitchenware, and can be an element or contaminant present in our daily life. Objective: To present a review of the main deleterious effects of Al on human health. Methods: The search was carried out from September 2022 to February 2023 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases, using scientific articles from 2012 to 2023. The quality of the studies was based on the GRADE instrument, and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusions: A total of 115 files were search returned. Further, 95 articles were evaluated, and 44 were included in this review. Based on the results, measuring Al's relevance to health is essential in medicine. Several studies have demonstrated clinical outcomes and metabolic alterations with Al exposure. The tolerable weekly intake established by the European Food Safety Authority (EFSA) of 1 mg Al/kg body weight can be achieved through dietary exposure alone. Proven neurotoxicity in humans is the critical adverse effect of Al. A carcinogenic effect of Al has not been proven so far. Preventive medicine advocates that exposure to Al should be kept as low as possible. Chelating agents, such as calcium disodium ethylene diamine tetraacetic acid and deferoxamine, are options for acute poisoning, and monomethysilanetriol supplementation may be a long-term strategy with chelation potential. Further studies are needed to assess the impacts of Al on human health.

Aluminum hydroxide exposure induces neurodevelopmental impairment in hESC-derived cerebral organoids

Aluminum (Al) has been classified as a cumulative environmental pollutant that endangers human health. There is increasing evidence to suggest the toxic effects of Al, but the specific action on human brain development remains unclear. Al hydroxide (Al(OH)₃), the most common vaccine adjuvant, is the major source of Al and poses risks to the environment and early childhood neurodevelopment. In this study, we explored the neurotoxic effect of 5 μg/ml or 25 μg/ml Al(OH)₃ for six days on neurogenesis by utilizing human cerebral organoids from human embryonic stem cells (hESCs). We found that early Al(OH)₃ exposure in organoids caused a reduction in the size, deficits in basal neural progenitor cell (NPC) proliferation, and premature neuron differentiation in a time and dose-dependent manner. Transcriptomes analysis revealed a markedly altered Hippo-YAP1 signaling pathway in Al(OH)₃ exposed cerebral organoid, uncovering a novel mechanism for Al(OH)₃-induced detrimental to neurogenesis during human cortical development. We further identified that Al(OH)₃ exposure at day 90 mainly decreased the production of outer radial glia-like cells(oRGs) but promoted NPC toward astrocyte differentiation. Taken together, we established a tractable experimental model to facilitate a better understanding of the impact and mechanism of Al(OH)₃ exposure on human brain development.

Aluminium in the Human Brain: Routes of Penetration, Toxicity, and Resulting Complications

Aluminium (Al) is the most ubiquitous metal in the Earth's crust. Even though its toxicity is well-documented, the role of Al in the pathogenesis of several neurological diseases remains debatable. To establish the basic framework for future studies, we review literature reports on Al toxicokinetics and its role in Alzheimer's disease (AD), autism spectrum disorder (ASD), alcohol use disorder (AUD), multiple sclerosis (MS), Parkinson's disease (PD), and dialysis encephalopathy (DE) from 1976 to 2022. Despite poor absorption via mucosa, the biggest amount of Al comes with food, drinking water, and inhalation. Vaccines introduce negligible amounts of Al, while the data on skin absorption (which might be linked with carcinogenesis) is limited and requires further investigation. In the above-mentioned diseases, the literature shows excessive Al accumulation in the central nervous system (AD, AUD, MS, PD, DE) and epidemiological links between greater Al exposition and their increased prevalence (AD, PD, DE). Moreover, the literature suggests that Al has the potential as a marker of disease (AD, PD) and beneficial results of Al chelator use (such as cognitive improvement in AD, AUD, MS, and DE cases).

Determination by ICP-MS of Essential and Toxic Trace Elements in Gums and Carrageenans Used as Food Additives Commercially Available in the Portuguese Market

Gums and carrageenans are food additives widely used in food preparations to improve texture and as viscosifiers. Although they are typically added in small amounts, nowadays people tend to use more and more pre-prepared food. In this work, the content of a wide panel of trace elements in commercial products were analyzed. Carrageenans and gums (n = 13) were purchased in the Portuguese market and were from European suppliers. Samples were solubilized by closed-vessel microwave-assisted acid digestion and analyzed by ICP-MS. Globally, the content of essential trace elements decreased in the following order: Fe (on average, on the order of several tens of µg/g) > Mn > Zn > Cr > Cu > Co > Se > Mo (typically < 0.1 µg/g), while the content of non-essential/toxic trace elements decreased in the following order: Al > Sr > Rb > As > Li > Cd > Pb > Hg. The consumption of these food additives can significantly contribute to the daily requirements of some essential trace elements, namely Cr and Mo. The toxic trace elements Cd, As, Pb, and Hg were below the EU regulatory limits in all analyzed samples. Additional research is needed to define the potential risk of introducing toxic trace elements into food products through the use of these additives.

Taurine and deferiprone against Al-linked apoptosis in rat hippocampus

BACKGROUND

Aluminium (Al) overload has toxic effects on multiple organ systems, especially the nervous system. Al accumulation in the brain, especially the hippocampus, is an important factor contributing to Alzheimer's disease (AD). Deferiprone (DFP), a metal chelator, is used as a potential treatment for AD. In this study, we investigated the combined effect of taurine and DFP on Al chelation and hippocampal apoptosis in Al-exposed rats, as well as the underlying mechanisms of these effects to explore a possible therapy for AD.

METHODS

Male Wistar rats were divided into seven groups: negative control group (administered saline), Al-exposure group (administered AlCl₃ and saline), and five experimental groups (administered AlCl₃ and taurine, varying doses of DFP, or taurine with varying doses of DFP). After 8 weeks of treatment, the rats were sacrificed, and the terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) assay was used to detect hippocampal apoptotic cells. Real-time quantitative PCR was used to assess the expression of the Bcl2 and Bax genes, and a western blotting assay was used to evaluate BCL2, BAX, and cleaved caspase-3 levels.

RESULTS

Compared to the negative control group, the number of apoptotic cells in the hippocampus increased, Bcl2 expression significantly decreased, and BAX and cleaved caspase-3 levels increased in the Al-exposure group. The combination of taurine and DFP exerted a protective effect by inhibiting hippocampal cell apoptosis through the BCL2, BAX, and caspase-3 signalling pathways. Compared with the taurine-administered group, the group administered taurine with DFP showed a significantly increased Bcl2 and decreased Bax expression.

CONCLUSION

The combination of taurine and DFP is a potential candidate for the treatment of AD induced by Al exposure.

Exposure to tolerable concentrations of aluminum triggers systemic and local oxidative stress and global proteomic modulation in the spinal cord of rats

The tolerable aluminum (Al) intake levels for humans are constantly under review by regulatory agencies due to novel pre-clinical evidence on the neurotoxicity of prolonged Al exposure; however, little is known about the effects of Al on the spinal cord. This study aimed to investigate potential adverse effects on both spinal cord and systemic biochemical balance after prolonged exposure to a low dose of Al. Twenty adult rats were distributed in the control (distilled water) and exposed group (8.3 mg of AlCl₃/kg/day). After 60 days, both blood and spinal cord samples were collected for oxidative stress and proteomic analyses. In plasma and erythrocytes, glutathione level was not different between groups; however, exposure to AlCl₃ significantly decreased glutathione level in the spinal cord. Thiobarbituric acid reactive substances levels in the plasma and spinal cord of animals from the control group were significantly lower than those animals exposed to AlCl₃. Exposure to AlCl₃ significantly modulated the expression of proteins associated with the cell cycle, stimulus-response, cytoskeleton, nervous system regulation, protein activity, and synaptic signaling. Therefore, prolonged exposure to a low dose of Al triggered oxidative stress and proteomic changes that may affect spinal cord homeostasis.

Magnesium alleviates aluminum-induced growth inhibition by enhancing antioxidant enzyme activity and carbon-nitrogen metabolism in apple seedlings

Previous studies have determined that magnesium (Mg) in appropriate concentrations prevents plants from suffering from abiotic stress. To better understand the mechanism of Mg alleviation of aluminum (Al) stress in apple, we investigated the effect of Mg on plant growth, photosynthetic fluorescence, antioxidant system, and carbon (C) and nitrogen (N) metabolism of apple seedlings under Al toxicity (1.5 mmol/L) via a hydroponic experiment. Al stress induced the production of reactive oxygen in the leaves and roots and reduced the total dry weight (DW) by 52.37 % after 20 days of treatment relative to plants grown without Al, due to hindered photosynthesis and alterations in C and N metabolism. By contrast, total DW decreased by only 11.07 % in the Mg-treated plants under Al stress. Supplementation with 3.0 mmol/L Mg in the Al treatment decreased Al accumulation in the apple plants and reduced Al-induced oxidative damage by enhancing the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) and reducing the production of H₂O₂ and malondialdehyde (MDA). Under Al stress, the Mg-treated plants showed a 46.17 % higher photosynthetic rate than the non-treated plants. Supplementation with Mg significantly increased the sucrose content by increasing sucrose synthase (SS) and sucrose-phosphate synthase (SPS) activities. Moreover, Mg facilitated the transport of ¹³C-carbohydrates from the leaves to roots. Regarding N metabolism, the nitrate reductase (NR), glutamine synthase (GS), and glutamate synthase (GOGAT) activities in the roots and leaves of the Mg-treated plants were significantly higher than those of the non-treated plants under Al stress. Compared with the non-treated plants under Al stress, the Mg-treated plants exhibited a significantly high level of NO₃^- and soluble protein content in the leaves, roots, and stems, but a low level of free amino acids. Furthermore, Mg significantly improved nitrogen accumulation and enhanced the transport of ¹⁵N from the roots to leaves. Overall, our results revealed that Mg alleviates Al-induced growth inhibition by enhancing antioxidant capacity and C-N metabolism in apple seedlings.

Centella asiatica Alleviates AlCl3-induced Cognitive Impairment, Oxidative Stress, and Neurodegeneration by Modulating Cholinergic Activity and Oxidative Burden in Rat Brain

Aluminum (Al) is linked to the development of many neurological disorders such as Alzheimer's disease (AD), Parkinson's disease, and autism. Centella asiatica (CA) is a regenerating herb traditionally used to stimulate memory. This study was designed to assess the neuroprotective role of ethanolic extract of CA (CAE) in AlCl₃-induced neurological conditions in rats. Adult rats were chronically treated with AlCl₃ (100 mg/kg b.w./day) for 60 days to establish the dementia model, and co-administration of CAE was evaluated for its ability to attenuate the toxic effect of AlCl₃. CAE was given orally at a dose of 150 and 300 mg/kg b.w./day, for 60 days. The behavioral performances of rats were tested through Y-maze and open field tests. Lipid peroxidation, superoxide dismutase, and catalase activity were evaluated to measure oxidative stress; and acetylcholinesterase (AChE) activity was assessed to evaluate cholinergic dysfunction in the rat brain. H&E staining was used to assess structural abnormalities in the cortex and hippocampus. The result showed that AlCl₃ induces cognitive dysfunction (impaired learning and memory, anxiety, diminished locomotor activity), oxidative stress, cholinergic impairment, and histopathological alteration in the rat brain. Co-administration of CAE with AlCl₃ markedly protects the brain from AlCl₃-induced cognitive dysfunction, oxidative stress, AChE activity, and cytoarchitectural alterations. Furthermore, 15 days CAE treatment after 45 days AlCl₃ administration markedly ameliorates the AlCl₃-induced neurotoxicity indicating its potential for therapeutic use.

Dietary Egg White Hydrolysate Prevents Male Reproductive Dysfunction after Long-Term Exposure to Aluminum in Rats

Aluminum (Al) is a non-essential metal omnipresent in human life and is considered an environmental toxicant. Al increases reactive oxygen production and triggers immune responses, contributing to chronic systemic inflammation development. Here, we have tested whether an egg white hydrolysate (EWH) with potential bioactive properties can protect against changes in reproductive function in rats exposed to long-term Al dietary levels at high and low doses. Male Wistar rats received orally: low aluminum level group-AlCl₃ at 8.3 mg/kg b.w. for 60 days with or without EWH (1 g/kg/day); high aluminum level group-AlCl₃ at 100 mg/kg b.w. for 42 days with or without EWH (1 g/kg/day). The co-administration of EWH prevented the increased Al deposition surrounding the germinative cells, reducing inflammation and oxidative stress in the reproductive organs. Furthermore, the daily supplementation with EWH maintained sperm production and sperm quality similar to those found in control animals, even after Al exposure at a high dietary contamination level. Altogether, our results suggest that EWH could be used as a protective agent against impairment in the reproductive system produced after long-term exposure to Al at low or high human dietary levels.

Neurobehavioral and Immunohistochemical Studies of the Cerebral Cortex Following Treatment with Ethyl Acetate Leaf Fraction of Tamarindus indica During Prenatal Aluminum Chloride Exposure in Wistar Rats

Purpose

The recent increase in aluminum exposure and its effect on the development of the brain call for serious attention. The study investigated the behavioral and immunohistochemical changes in the cerebral cortex of Wistar rats following prenatal co-administration of ethyl acetate leaf fraction of Tamarindus indica (EATI) and aluminum chloride (AlCl3).

Methods

Pregnant Wistar rats were divided into 5 groups (n=4). Group I (negative control), Group II-V were experimental groups treated with 200 mg/kg of AlCl3 s/c. Group III and IV received an additional 400 mg/kg and 800 mg/kg of EATI respectively, while Group V received an additional 300 mg/kg of Vitamin E for 14 days (prenatal days 7-21) via the oral route. The pups were then exposed to cliff avoidance, negative geotaxis, and elevated plus maze (EPM) test on the post-natal day (PoND) 4-6, 7-10, and 18 respectively. On PoND 21 pups were sacrificed, and the skull dissected to remove the brain. The harvested brain tissues were processed for Cresyl fast (CF) and glial fibrillary acid protein (GFAP).

Results

The study showed that EATI administration during AlCl3 exposure was associated with significant improvement in sensory-motor development. The EPM, CF, and GFAP results revealed significant improvement in anxiety-like behavior, motor activities, GFAP expression, pyramidal cell count, and Nissl staining following prenatal EATI administration during AlCl3 exposure.

Conclusion

The present study concludes that EATI was associated with some protective potential during prenatal AlCl3 exposure in Wistar rats.

In Vitro and In Vivo Neuroprotective Effects of Sarcosine

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by behavioral and psychological symptoms in addition to cognitive impairment and loss of memory. The exact pathogenesis and genetic background of AD are unclear and there remains no effective treatment option. Sarcosine, an n-methyl derivative of glycine, showed a promising therapeutic strategy for some cognitive disorders. To our knowledge, the impacts of sarcosine supplementation against AD have not yet been elucidated. Therefore, we aimed to determine the neuroprotective potential of sarcosine in in vitro and in vivo AD model. In vitro studies have demonstrated that sarcosine increased the percentage of viable cells against aluminum induced neurotoxicity. In AlCl₃-induced rat model of AD, the level of antioxidant capacity was significantly decreased and expression levels of APP, BACE1, TNF-α, APH1A, and PSENEN genes were elevated compared to the control group. Additionally, histopathological examinations of the hippocampus of AlCl₃-induced rat brains showed the presence of neurofibrillary tangles (NFTs). However, the administration of sarcosine produced marked improvement and protection of AD-associated pathologies induced by AlCl₃ in experimental rats. Therefore, this investigation may contribute to design novel therapeutic strategies using sarcosine for the management of AD pathologies.

Exposure of aluminium to C6 glioma cells modulates molecular and functional neurotoxic markers

The risk of aluminium exposure to humans is very high as it may get into the human body through excessive dietary contaminants, inhalation of fine particulate matter, or through parenteral routes as a vaccine adjuvant and so forth. The increased level of aluminium in brain tissue has been shown to be associated with several neurodegenerative and neurotoxic adverse effects, including AD. However, the exact mechanism of aluminium-induced neurotoxicity is still unclear. Therefore, our study aimed to investigate the mechanism of neurotoxic and neurodegenerative effects through in vitro exposure of aluminium in rat glioma C6 cell line. The findings of our study have indicated that aluminium chloride exposure may lead to alteration in acetylcholine levels, increased oxidative imbalance and induction of molecular structural and functional markers of neuronal inflammation. This study also demonstrated that aluminium exposure may lead to the induction of caspase-3 along with apoptotic cell death and a significant increase in amyloid-beta and hyperphosphorylated tau levels in C6 cells. Thus, this study may provide a mechanistic understanding of the regulation of neuroinflammatory and neurodegenerative biomarkers due to aluminium exposure.

Inflammation and Autophagy: A Convergent Point between Autism Spectrum Disorder (ASD)-Related Genetic and Environmental Factors: Focus on Aluminum Adjuvants

Autism spectrum disorder (ASD), schizophrenia, and bipolar disorder are genetically complex and heterogeneous neurodevelopmental disorders (NDDs) resulting from genetic factors and gene-environment (GxE) interactions for which onset occurs in early brain development. Recent progress highlights the link between ASD and (i) immunogenetics, neurodevelopment, and inflammation, and (ii) impairments of autophagy, a crucial neurodevelopmental process involved in synaptic pruning. Among various environmental factors causing risk for ASD, aluminum (Al)-containing vaccines injected during critical periods have received special attention and triggered relevant scientific questions. The aim of this review is to discuss the current knowledge on the role of early inflammation, immune and autophagy dysfunction in ASD as well as preclinical studies which question Al adjuvant impacts on brain and immune maturation. We highlight the most recent breakthroughs and the lack of epidemiological, pharmacokinetic and pharmacodynamic data constituting a "scientific gap". We propose additional research, such as genetic studies that could contribute to identify populations at genetic risk, improving diagnosis, and potentially the development of new therapeutic tools.

A simple "turn-on" fluorescent sensor for reversible recognition of aluminum ion in living cell

A simple and reliable "turn-on" fluorescent sensor (E)-1-[((2-hydroxyethyl)imino) methyl] naphthalen-2-ol (HNP) has been designed, synthesized, and characterized by ¹H-NMR, ¹³C-NMR, FT-IR, and EI-MS analysis. The binding property of HNP was examined employing UV-Vis and fluorescence spectroscopy. HNP exhibited high selectivity towards Al³⁺ among other cations and anions. The fluorescence titration experiment has established binding stoichiometry of HNP with Al³⁺ is 2:1, which can be further verified by HR-MS. The detection limit of HNP is 2.9 μM, and it can be reversible five-to-seven times to detect Al³⁺ without losing much efficiency which indicates that it can be a reliable probe for Al³⁺. Additionally, HNP was successfully applied for the detection of Al³⁺ in living cells. To achieve the detection of aluminum ion across a simple, reliable, and precise method, we have investigated the reversible detection (which can reversible response to Al³⁺ for five-to-seven times) of Al³⁺ through an extremely simple (requires only one-step reaction) "turn-on" fluorescent probe which enables us to visualize and analyze Al³⁺ with low detection limit (2.9 μM) and high selectivity in living cell without interference from the high abundant small biological molecules.

Monitoring mild cognitive impairment of workers exposed to occupational aluminium based on quantitative susceptibility mapping

AIM

To investigate the diagnostic value of quantitative susceptibility mapping (QSM) in mild cognitive impairment (MCI) of aluminium (Al) workers.

MATERIALS AND METHODS

The basic data of 53 workers in an Al factory were collected and divided into the MCI group and normal control (NC) group by Montreal Cognitive Assessment (MoCA) scores. All participants were tested for plasma Al concentration and had magnetic resonance imaging (MRI). The QSM values of many areas of the brain were delineated and measured. Independent two-sample t-tests or non-parametric tests were used to compare the parameter values between the two groups. Spearman's correlation analysis was performed between QSM values, MoCA scores, and plasma Al concentration. The receiver operating characteristic curve and z test were performed to assess diagnostic efficacy and the best parameter.

RESULTS

There was no difference in age and educational level. Plasma Al concentration of the MCI group was higher than that of NC group (p=0.057). QSM values of the left hippocampus, left dentate nucleus, right substantia nigra, and left putamen in MCI group were higher than that of NC group (p<0.05), and the left hippocampus had the best diagnostic efficacy. QSM values correlated negatively with MoCA scores. No correlation was found between QSM values and plasma Al concentration (p>0.05).

CONCLUSION

QSM might be a neuroimaging marker for the diagnosis of MCI. The left hippocampus showed the best diagnostic efficacy. Plasma Al concentration of the MCI group was higher than that of the NC group. A correlation between QSM and plasma Al concentration was not found.

Clearance, biodistribution, and neuromodulatory effects of aluminum-based adjuvants. Systematic review and meta-analysis: what do we learn from animal studies?

Aluminum (Al) salts are commonly used as adjuvants in human and veterinary vaccines for almost a century. Despite this long history of use and the very large number of exposed individuals, data in the literature concerning the fate of these molecules after injection and their potential effects on the nervous system is limited. In the context of (i) an increase of exposure to Al salts through vaccination; (ii) the absence of safety values determined by health regulators; (iii) the lack of robustness of the studies used as references to officially claim Al adjuvant innocuity; (iv) the publication of several animal studies investigating Al salts clearance/biopersistence and neurotoxicity; we have examined in this review all published studies performed on animals and assessing Al adjuvants kinetics, biodistribution, and neuromodulation since the first work of A. Glenny in the 1920s. The diversity of methodological approaches, results, and potential weaknesses of the 31 collected studies are exposed. A large range of protocols has been used, including a variety of exposure schedule and analyses methods, making comparisons between studies uneasy. Nevertheless, published data highlight that when biopersistence, translocation, or neuromodulation were assessed, they were documented whatever the different in vivo models and methods used. Moreover, the studies pointed out the crucial importance of the different Al adjuvant physicochemical properties and host genetic background on their kinetics, biodistribution, and neuromodulatory effects. Regarding the state of the art on this key public health topic, further studies are clearly needed to determine the exact safety level of Al salts.

Second Sphere Interactions in Amyloidogenic Diseases

Amyloids are protein aggregates bearing a highly ordered cross β structural motif, which may be functional but are mostly pathogenic. Their formation, deposition in tissues and consequent organ dysfunction is the central event in amyloidogenic diseases. Such protein aggregation may be brought about by conformational changes, and much attention has been directed toward factors like metal binding, post-translational modifications, mutations of protein etc., which eventually affect the reactivity and cytotoxicity of the associated proteins. Over the past decade, a global effort from different groups working on these misfolded/unfolded proteins/peptides has revealed that the amino acid residues in the second coordination sphere of the active sites of amyloidogenic proteins/peptides cause changes in H-bonding pattern or protein-protein interactions, which dramatically alter the structure and reactivity of these proteins/peptides. These second sphere effects not only determine the binding of transition metals and cofactors, which define the pathology of some of these diseases, but also change the mechanism of redox reactions catalyzed by these proteins/peptides and form the basis of oxidative damage associated with these amyloidogenic diseases. The present review seeks to discuss such second sphere modifications and their ramifications in the etiopathology of some representative amyloidogenic diseases like Alzheimer's disease (AD), type 2 diabetes mellitus (T2Dm), Parkinson's disease (PD), Huntington's disease (HD), and prion diseases.

Chronic oral exposure of aluminum chloride in rat modulates molecular and functional neurotoxic markers relevant to Alzheimer's disease

Aluminum is an environmentally abundant potential neurotoxic agent that may result in oxidative damage to a range of cellular biomarkers. The potential sources of aluminum accumulation in body include drinking water, food, medicines, vaccines, and aluminum cookware utensils etc. The accumulation of aluminum in brain is reported to be associated with cholinergic dysfunction, oxidative stress and neuronal damage, that may ultimately cause Alzheimer's disease. Since chronic exposure of aluminum leads to its accumulation in brain, so this study was done by a long-term (24 weeks) low dose (20 mg/kg) oral exposure of aluminum chloride in rats. In this chronic model, we have evaluated the major hallmarks of Alzheimer's disease including amyloid beta (Aβ_1-42) and phosphorylated-tau (p231-tau) protein in brain tissue. Furthermore, we evaluated the level of acetyl cholinesterase activity, inflammatory cytokines such as TNF-α, IL-6 and IL-1β, and oxidative stress biomarkers in rat brain in this model. The neurobehavioral parameters were also assessed in animals by using spontaneous locomotor activity, passive avoidance, rotarod test and novel object recognition test to evaluate alteration in learning, memory and muscle co-ordination. We found that chronic oral exposure of aluminum chloride causes a significant increase in structural hallmarks such as Aβ_1-42 and p231-tau levels along with proinflammatory cytokines (TNF-α and IL-6), oxidative stress, and a decrease in antioxidant markers such as GSH and catalase. in the brain tissue. These biomarkers significantly affected neurobehavioral parameters in animals. This study provides a mechanistic understanding of chronic aluminum-induced neuronal toxicity in brain with relevance to Alzheimer's disease.

Subacute exposure to aluminum chloride causes prolonged morphological insults in the ventral male prostate and in the female prostate of adult gerbils

Aluminum (Al) is a widespread metal in the environment, and is found in fresh or processed foods, household utensils, packaging, and medicines. In addition to its high toxicity, Al can also have estrogenic agonistic effects on target organs. Considering that the Al effects on the prostate are little known, the aim of this study was to evaluate the impact of aluminum chloride (AlCl₃ ) subacute exposure on the morphophysiology of the male ventral prostate and the female prostate of adult gerbils. Furthermore, the glandular restoration capacity in face of the Al insults was evaluated in gerbils that were submitted to 30 days of recovery. Male and female gerbils were orally exposed to AlCl₃ (10 mg/kg) for 30 consecutive days. The animals were euthanized 1 day (Al1D) or 30 days (Al30D) after the end of treatment. Prostates were dissected out and processed for structural, ultrastructural and immunohistochemical analyses. Male ventral prostates and female prostates of the Al1D group showed increased cell proliferation, glandular hyperplasia, increased secretory activity and greater androgen receptor immunoreactivity. In males, Al withdrawal (Al30D) allowed a partial recovery of the prostate, as the glandular secretory activity, and frequency of androgen receptor positive cells were similar to the control group. In females, the recuperation interval (Al30D) was not enough to restore the prostatic morphology, since the gland remained hyperplastic, proliferative, and with greater androgen and estrogen receptor immunoreactivity. These data alert to the importance of avoiding Al exposure, since this metal can have a harmful and prolonged action on the prostate.

Neurotoxic effects of aluminium exposure as a potential risk factor for Alzheimer's disease

Aluminium is one of the most widely distributed elements of the Earth's crust. Its routine use has resulted in excessive human exposure and due to the potential neurotoxic effects has attained a huge interest in recent years. Despite its ubiquitous abundance, aluminium has no crucial biological functions in the human body. Oxidative stress and neuroinflammatory effects are attributed to its neurotoxic manifestations implicated in Alzheimer's disease. In this review, we have discussed the neuroinflammatory and neurodegenerative events in the brain induced by aluminium exposure. We have highlighted the neurotoxic events caused by aluminium, such as oxidative stress, apoptosis, inflammatory events, calcium dyshomeostasis, Aβ deposition, and neurofibrillary tangle formation in the brain. In addition, the protective measures needed for prevention of aluminium-induced neuronal dysregulations have also been discussed.

Aluminum Poisoning with Emphasis on Its Mechanism and Treatment of Intoxication

Aluminum poisoning has been reported in some parts of the world. It is one of the global health problems that affect many organs. Aluminum is widely used daily by humans and industries. Residues of aluminum compounds can be found in drinking water, food, air, medicine, deodorants, cosmetics, packaging, many appliances and equipment, buildings, transportation industries, and aerospace engineering. Exposure to high levels of aluminum compounds leads to aluminum poisoning. Aluminum poisoning has complex and multidimensional effects, such as disruption or inhibition of enzymes activities, changing protein synthesis, nucleic acid function, and cell membrane permeability, preventing DNA repair, altering the stability of DNA organization, inhibition of the protein phosphatase 2A (PP2A) activity, increasing reactive oxygen species (ROS) production, inducing oxidative stress, decreasing activity of antioxidant enzymes, altering cellular iron homeostasis, and changing NF-kB, p53, and JNK pathway leading to apoptosis. Aluminum poisoning can affect blood content, musculoskeletal system, kidney, liver, and respiratory and nervous system, and the extent of poisoning can be diagnosed by assaying aluminum compounds in blood, urine, hair, nails, and sweat. Chelator agents such as deferoxamine (DFO) are used in the case of aluminum poisoning. Besides, combination therapies are recommended.

Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations

Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.

Damage to Olfactory Organs of Adult Zebrafish Induced by Diesel Particulate Matter

Particulate matter (PM) is an environmental hazard that is associated with various human health risks. The olfactory system is directly exposed to PM; therefore, the influence of PM exposure on olfactory function must be investigated. In this study, we propose a zebrafish olfactory model to evaluate the effects of exposure to diesel particulate matter (DPM), which was labeled Korean diesel particulate matter (KDP20). KDP20 comprises heavy metals and polycyclic aromatic hydrocarbons (PAHs). KDP20 exposed olfactory organs exhibited reduced cilia and damaged epithelium. Olfactory dysfunction was confirmed using an odor-mediated behavior test. Furthermore, the olfactory damage was analyzed using Alcian blue and anti-calretinin staining. KDP20 exposed olfactory organs exhibited histological damages, such as increased goblet cells, decreased cell density, and calretinin level. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed that PAHs exposure related genes (AHR2 and CYP1A) were upregulated. Reactive oxidation stress (ROS) (CAT) and inflammation (IL-1B) related genes were upregulated. Furthermore, olfactory sensory neuron (OSN) related genes (OMP and S100) were downregulated. In conclusion, KDP20 exposure induced dysfunction of the olfactory system. Additionally, the zebrafish olfactory system exhibited a regenerative capacity with recovery conditions. Thus, this model may be used in future investigating PM-related diseases.

A geostatistical approach to estimating source apportionment in urban and peri-urban soils using the Czech Republic as an example

Unhealthy soils in peri-urban and urban areas expose individuals to potentially toxic elements (PTEs), which have a significant influence on the health of children and adults. Hundred and fifteen (n = 115) soil samples were collected from the district of Frydek Mistek at a depth of 0-20 cm and measured for PTEs content using Inductively coupled plasma-optical emission spectroscopy. The Pearson correlation matrix of the eleven relevant cross-correlations suggested that the interaction between the metal(loids) ranged from moderate (0.541) correlation to high correlation (0.91). PTEs sources were calculated using parent receptor model positive matrix factorization (PMF) and hybridized geostatistical based receptor model such as ordinary kriging-positive matrix factorization (OK-PMF) and empirical Bayesian kriging-positive matrix factorization (EBK-PMF). Based on the source apportionment, geogenic, vehicular traffic, phosphate fertilizer, steel industry, atmospheric deposits, metal works, and waste disposal are the primary sources that contribute to soil pollution in peri-urban and urban areas. The receptor models employed in the study complemented each other. Comparatively, OK-PMF identified more PTEs in the factor loadings than EBK-PMF and PMF. The receptor models performance via support vector machine regression (SVMR) and multiple linear regression (MLR) using root mean square error (RMSE), R square (R2) and mean square error (MAE) suggested that EBK-PMF was optimal. The hybridized receptor model increased prediction efficiency and reduced error significantly. EBK-PMF is a robust receptor model that can assess environmental risks and controls to mitigate ecological performance.

Whole-transcriptome analysis of aluminum-exposed rat hippocampus and identification of ceRNA networks to investigate neurotoxicity of Al

Aluminum is a known neurotoxin that can induce Aβ deposition and abnormal phosphorylation of tau protein, leading to Alzheimer disease (AD)-like damages such as neuronal damage and decreased learning and memory functions. In this study, we constructed a rat model of subchronic aluminum maltol exposure, and the whole-transcriptome sequencing was performed on the hippocampus of the control group and the middle-dose group. A total of 167 miRNAs, 37 lncRNAs, 256 mRNAs, and 64 circRNAs expression changed. The Kyoto Encyclopedia of Genes and Genomes showed that PI3K/AKT pathway was the most enriched pathway of DEGs, and IRS1 was the core molecule in the PPI network. circRNA/lncRNA-miRNA-mRNA networks of all DEGs, DEGs in the PI3K/AKT pathway, and IRS1 were constructed by Cytoscape. Molecular experiment results showed that aluminum inhibited the IRS1/PI3K/AKT pathway and increased the content of Aβ and tau. In addition, we also constructed an AAV intervention rat model, proving that inhibition of miR-96-5p expression might resist aluminum-induced injury by upregulating expression of IRS1. In general, these results suggest that the ceRNA networks are involved in the neurotoxic process of aluminum, providing a new strategy for studying the toxicity mechanism of aluminum and finding biological targets for the prevention and treatment of AD.

Was amorphous aluminium hydroxyphosphate sulfate adequately evaluated before authorisation in Europe?

The Merck Sharp & Dohme Corp aluminium adjuvant 'amorphous aluminium hydroxyphosphate sulfate' (AAHS), primarily used in the Gardasil vaccines against human papilloma virus, has been criticised for lack of evidence for its safety. Documentation from Danish authorities and answers from the European Medicines Agency (EMA) suggest that AAHS may not have been sufficiently evaluated. Documentation from the Danish Medicines Agency shows discrepancies in the trial documents of two prelicensure clinical trials with Gardasil in 2002 and 2003. For both trials, the Agency seems to have authorised potassium aluminium sulfate as the adjuvant and not AAHS. In addition, the participants in the trial launched in 2002 were informed that the comparator was saline, even though the comparator was AAHS in an expedient consisting of L-histidine, polysorbate-80, sodium borate and sodium chloride. According to the EMA, AAHS was first introduced in Europe in 2004 as the adjuvant in Procomvax, a vaccine against the hepatitis B virus and Haemophilus influenza type b. The EMA reports that AAHS was introduced without any prelicensure safety evaluation. The adjuvant is described by the company to be both physically and functionally distinct from all other previously used aluminium adjuvants. There is a need for rigorous evaluation of benefits and harms of the adjuvant AAHS.

Combination of donepezil and gallic acid improves antioxidant status and cholinesterases activity in aluminum chloride-induced neurotoxicity in Wistar rats

The present study compared the effect of donepezil only and combination of donepezil and gallic acid on oxidative status and cholinesterase activity in the brain of Wistar rats administered AlCl₃ for 60 days. Twenty-eight rats (180 - 200 g) were arbitrarily distributed into four groups of seven animals apiece. Group 1 served as normal control and received distilled water throughout the study. Group 2 animals received only AlCl₃ throughout the study while animals in groups 3 and 4 were administered donepezil only (10 mg/kg) and combination of donepezil (10 mg/kg) and gallic acid (50 mg/kg), respectively, in addition to AlCl₃. Treatments were administered orally by gavage. At the end of the study, animals were sacrificed and activities of acetylcholinesterase, butyrylcholinesterase, superoxide dismutase (SOD) and catalase as well as levels of malondialdehyde (MDA), total thiol and nitric oxide (NO) were evaluated in the brain. Histopathological study was conducted on the hippocampus of experimental animals. Results showed that AlCl₃ significantly (p < 0.05) increased brain activities of cholinesterases and levels of MDA and NO with a concomitant decrease in total thiol level as well as activities of SOD and catalase. Donepezil only and combination of donepezil and gallic acid reversed these alterations. Also, combination of donepezil and gallic acid significantly (p < 0.05) improved antioxidant status better than donepezil only. It could be concluded that a synergy might exist between gallic acid and donepezil especially in ameliorating oxidative stress associated with AlCl₃-induced neurotoxicity.