Mercury exposure, serum antinuclear/antinucleolar antibodies, and serum cytokine levels in mining populations in Amazonian Brazil: a cross-sectional study

The impact of mercury exposure on male reproduction: Mechanistic insights

Mercury is a pervasive environmental toxin with significant negative effects on human health. In occupational settings, incidents such as the Minamata and Niigata disease in Japan and the large-scale methylmercury poisoning in Iraq have highlighted the severe health impacts of mercury exposure. It is widely accepted that all forms of mercury including methylmercury and mercuric chloride have the potential to induce toxic effects in mammals, and there is increasing concern about the impact of environmentally relevant levels of mercury on reproductive functions. This review summarizes current knowledge on the mechanisms of mercury toxicity, focusing specifically on its impact on male reproductive health across species. We searched the literature and found that mercury exposure is associated with testicular degeneration, altered spermatogenesis, and Leydig cell deformation. In addition, mercury can disrupt sperm motility, steroidogenesis and interfere with the hypothalamic-pituitary-gonadal axis by generation of reactive oxygen species, inducing mitochondrial dysfunction, epigenetic changes, and DNA damage. At the molecular level, mercury has been found to dysregulate the expression of key steroidogenic and spermatogenic genes, significantly reducing overall fertility potential. However, specific mechanisms of action remain to be fully elucidated. Similarly, comprehensive data on the potential transgenerational effects of paternal mercury exposure are lacking. In this review, we discuss both animal and human studies, and highlight the need for further research due to lack of standardization and control for variables such as lifestyle, immune system function, and exposure concentrations.

Exposure to Gold Induces Autoantibodies against Nuclear Antigens in A.TL Mice

To demonstrate causation or/and assess pathogenic mechanisms of environment-induced autoimmunity, various animal models that mimic the characteristics of the human autoimmune diseases need to be developed. Experimental studies in mice reveal the genetic factors that contribute to autoimmune diseases. Here, the immune response of two mouse strains congenic for non-H-2 genes, A.TL (H-2tl) and A.SW (H-2s), was evaluated after 15 weeks' exposure to gold aurothiomalate (AuTM). AuTM-treated A.TL mice showed anti-nuclear antibodies (ANA) with homogenous and/or fine speckled staining patterns and serum autoantibodies to ds-DNA, chromatin, histones, and ribonucleoproteins (RNP). Female A.TL mice showed a stronger immune response than males, as well as an increase of B cells in their spleen after 15 weeks of gold exposure. A.SW exposed for AuTM showed the induction of anti-nucleolar antibodies (ANoA) with a clumpy staining pattern, as well as an increase in splenic B and T cells. The serum autoantibodies levels in A.SW mice were limited compared to those of A.TL mice. Overall, A.TL presents a stronger immune response after gold exposure than A.SW. The immune response developed in A.TL presents similarities with the clinical manifestations in human autoimmune diseases. Thus, gold-exposed A.TL could constitute a potential experimental mouse model for the study of autoimmunity.

Evolving understanding of autoimmune mechanisms and new therapeutic strategies of autoimmune disorders

Autoimmune disorders are characterized by aberrant T cell and B cell reactivity to the body's own components, resulting in tissue destruction and organ dysfunction. Autoimmune diseases affect a wide range of people in many parts of the world and have become one of the major concerns in public health. In recent years, there have been substantial progress in our understanding of the epidemiology, risk factors, pathogenesis and mechanisms of autoimmune diseases. Current approved therapeutic interventions for autoimmune diseases are mainly non-specific immunomodulators and may cause broad immunosuppression that leads to serious adverse effects. To overcome the limitations of immunosuppressive drugs in treating autoimmune diseases, precise and target-specific strategies are urgently needed. To date, significant advances have been made in our understanding of the mechanisms of immune tolerance, offering a new avenue for developing antigen-specific immunotherapies for autoimmune diseases. These antigen-specific approaches have shown great potential in various preclinical animal models and recently been evaluated in clinical trials. This review describes the common epidemiology, clinical manifestation and mechanisms of autoimmune diseases, with a focus on typical autoimmune diseases including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and sjögren's syndrome. We discuss the current therapeutics developed in this field, highlight the recent advances in the use of nanomaterials and mRNA vaccine techniques to induce antigen-specific immune tolerance.

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.

Mercury-induced toxicity: Mechanisms, molecular pathways, and gene regulation

Mercury is a well-known neurotoxicant for humans and wildlife. The epidemic of mercury poisoning in Japan has clearly demonstrated that chronic exposure to methylmercury (MeHg) results in serious neurological damage to the cerebral and cerebellar cortex, leading to the dysfunction of the central nervous system (CNS), especially in infants exposed to MeHg in utero. The occurrences of poisoning have caused a wide public concern regarding the health risk emanating from MeHg exposure; particularly those eating large amounts of fish may experience the low-level and long-term exposure. There is growing evidence that MeHg at environmentally relevant concentrations can affect the health of biota in the ecosystem. Although extensive in vivo and in vitro studies have demonstrated that the disruption of redox homeostasis and microtube assembly is mainly responsible for mercurial toxicity leading to adverse health outcomes, it is still unclear whether we could quantitively determine the occurrence of interaction between mercurial and thiols and/or selenols groups of proteins linked directly to outcomes, especially at very low levels of exposure. Furthermore, intracellular calcium homeostasis, cytoskeleton, mitochondrial function, oxidative stress, neurotransmitter release, and DNA methylation may be the targets of mercury compounds; however, the primary targets associated with the adverse outcomes remain to be elucidated. Considering these knowledge gaps, in this article, we conducted a comprehensive review of mercurial toxicity, focusing mainly on the mechanism, and genes/proteins expression. We speculated that comprehensive analyses of transcriptomics, proteomics, and metabolomics could enhance interpretation of "omics" profiles, which may reveal specific biomarkers obviously correlated with specific pathways that mediate selective neurotoxicity.

Serum Level Alteration of IL-6, IL-1β, and IFN-γ in Groups of Healthy Adults with Oxidative DNA Damage in Najaf Governorate

Background

Najaf governorate was recorded as one of the most polluted Iraqi governorates with increased cancer, autoimmune, and abortion cases. Study Groups. A total of 88 adult volunteers from three test groups were divided based on their inhabitance in different geographical regions in Najaf governorate. Group 1 (G1; n, 29) inhabitants of Al-Ansar, Al-Abbaseyeh, and Al-Manathera districts, Group 2 (G2; n, 27) inhabitants of 22 different scattered districts of the governorate, Group 3 (G3; n, 32) inhabitants of Kufa city and center districts in the old Najaf city. According to previous authors' findings, all participants had uranium contamination in their urine and blood samples, and also, they had DNA damage according to the level of urinary 8-OHdG compound. The control group 4 (G4; n, 25) were adult healthy Iraqi volunteers who were residents of the Sulaimaniyah governorate, which has low-level uranium pollution. The present study aims to determine the effect of uranium pollution and DNA damage on the immune system function in terms of estimating the levels of serum interleukin (IL)-6, interferon-gamma (IFN-γ), and IL-1 beta (β).

Method

Enzyme-linked immunosorbent assay (ELISA) (Sandwich method technique) was used for estimating the serum cytokines levels in test and control groups.

Results

A significant elevation of cytokines levels was reported as compared with the control groups (p ≤ 0.01). The level of IL-6 was 764.64 ± 24.12 pg/ml, 768.87 ± 19.64 pg/ml, and 735.62 ± 18.47 in G1, G2, and G3, respectively. The level of IFN-γ was 264.55 ± 19.17 pg/ml, 259 ± 18.76 pg/ml, and 261.20 ± 12.99 pg/ml for G1, G2, and G3, respectively. The level of IL-1β was 99.85 ± 10.81 pg/ml, 116.8 ± 10.71 pg/ml, and 83 ± 19.24 pg/ml in G1, G2, and G3, respectively. The levels of IL-6, IFN-γ, and IL-1β were 86.5 ± 22.9 pg/ml, 19.4 ± 2.8 pg/ml, and 16.1 ± 3.2 pg/ml in the sera of control (G4). The results showed significant statistical elevation with the corresponding p value cut-off p ≤ 0.01 in IL-6, IFN-γ, and IL-1β in the sera of three test groups as compared with the results of the control group.

Conclusion

The change in the proinflammatory cytokines (IL-6, IFN-γ, and IL-1β) levels indicates a persistent inflammatory response in the participants and may reflect immune system impairment as a consequence of exposure to long-term low-dose ionizing radiation.

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Serum levels of inflammatory cytokines in mercury mining workers in a precarious situation: A preliminary study

Mercury is a ubiquitous environmental xenobiotic; the primary sources of exposure to this metal are artisanal gold mining and the direct production of mercury. In Mexico, artisanal mercury mining continues to be an important activity in different regions of the country. Exposure to mercury vapors releases can have severe health impacts, including immunotoxic effects such as alterations in cytokine profiling. Therefore, in the present work, we evaluated the inflammatory cytokines profile in the blood serum of miners exposed to mercury. A cross-sectional observational study was performed on 27 mining workers (exposed group) and 20 control subjects (nonexposed group) from central Mexico. The mercury urine concentration (U-Hg) was determined by atomic absorption spectrometry, and IL-2, IL-6, IL-8, IL-10, and TNF-α were measured using a Multiplex Assay. The results showed that the U-Hg in the miners had a median value of 552.70 μg/g creatinine. All cytokines showed a significant increase in the miner group compared with the control group, except for TNF-α. In addition, we observed a positive correlation between U-Hg concentration and cytokine levels. In conclusion, mercury exposure correlated with cytokine levels (considered acute inflammatory marker) in miners; therefore, workers exposed to this metal show an acute systemic inflammation that could lead to alterations in other organs and systems.

HgCl2 exposure mediates pyroptosis of HD11 cells and promotes M1 polarization and the release of inflammatory factors through ROS/Nrf2/NLRP3

Mercury (Hg) is a serious metal environmental pollutant. HgCl2 exposure causes pyroptosis. When macrophages are severely stimulated, they often undergo M1 polarization and release inflammatory factors. However, the mechanisms by which mercuric chloride exposure induces macrophage apoptosis, M1 polarization, and inflammatory factors remain unclear. HD11 cells were exposed to different concentrations of Hg chloride (180, 210 and 240 nM HgCl2). The results showed that mercury chloride exposure up-regulated ROS, C-Nrf2 and its downstream factors (NQO1 and HO-1), and down-regulated N-Nrf2. In addition, the expressions of focal death-related indicators (Caspase-1, NLRP3, GSDMD, etc.), M1 polarization marker CD86 and inflammatory factors (TNF-α, IL-1β) increased, and the above changes were related to mercury. Oxidative stress inhibitor (NAC) can block ROS/ NrF2-mediated oxidative stress, inhibit mercury-induced pyroptosis and M1 polarization, and effectively reduce the release of inflammatory factors. The addition of Vx-765 to inhibit pyroptosis can effectively alleviate M1 polarization of HD11 cells and reduce the expression of inflammatory factors. HgCl2 mediates pyroptosis of HD11 cells by regulating ROS/Nrf2/NLRP3, promoting M1 polarization and the release of inflammatory factors.

Association between mercury exposure and lung function in young adults: A prospective cohort study in Shandong, China

BACKGROUND

Mercury has been associated with many adverse health outcomes. However, limited studies have explored the association between blood mercury concentrations and lung function.

OBJECTIVE

To examine the association between blood mercury concentrations and lung function among young adults.

METHODS

We conducted a prospective cohort study among 1800 college students based on the Chinese Undergraduates Cohort in Shandong, China during August 2019 and September 2020. Lung function indicators including forced vital capacity (FVC, ml), forced expiratory volume in 1 s (FEV₁, ml) and peak expiratory flow (PEF, ml) were collected with a spirometers (Chestgraph Jr. HI-101, Chest M.I., Tokyo, Japan). The blood mercury concentration was measured using inductively coupled plasma mass spectrometry. We divided participants into low (≤25 percentiles), intermediate (25-75 percentiles), and high (≥75 percentile) subgroups according to blood mercury concentrations. The multiple linear regression model was used to examine the associations between blood mercury concentrations and lung function changes. Stratification analyses by sex and fish consumption frequency were also conducted.

RESULTS

The results showed that each 2-fold increase in blood mercury concentrations was significantly associated with -70.75 ml [95 % confidence interval (CI): -122.35, -19.15] change in FVC, -72.68 ml (95%CI: -120.36, -25.00) in FEV₁, and -158.06 ml (95%CI: -283.77, -32.35) in PEF. The effect was more pronounced among participants with high blood mercury and male participants. Participants who consumed fish more than once a week more likely to be affected by mercury.

CONCLUSION

Our study indicated that blood mercury was significantly associated with decreased lung function in young adults. It is necessary to implement corresponding measures to reduce the effect of mercury on the respiratory system, especially for men and people who consumed fish more than once a week.

Amelioration of nephritis in receptor for advanced glycation end-products (RAGE)-deficient lupus-prone mice through neutrophil extracellular traps

The receptor for advanced glycation end-products (RAGE) is a pattern recognition receptor that regulates inflammation, cell migration, and cell fate. Systemic lupus erythematosus (SLE) is a chronic multiorgan autoimmune disease. To understand the function of RAGE in SLE, we generated RAGE-deficient (Ager-/-) lupus-prone mice by backcrossing MRL/MpJ-Faslpr/J (MRL-lpr) mice with Ager-/- C57BL/6 mice. In 18-week-old Ager-/- MRL-lpr, the weights of the spleen and lymph nodes, as well as the frequency of CD3+CD4-CD8- cells, were significantly decreased. Ager-/- MRL-lpr mice had significantly reduced urine albumin/creatinine ratios and markedly improved renal pathological scores. Moreover, neutrophil infiltration and neutrophil extracellular trap formation in the glomerulus were significantly reduced in Ager-/- MRL-lpr. Our study is the first to reveal that RAGE can have a pathologic role in immune cells, particularly neutrophils and T cells, in inflammatory tissues and suggests that the inhibition of RAGE may be a potential therapeutic strategy for SLE.

Risk assessment of heavy metals in tuna from Japanese restaurants in the Republic of Korea

Background

Studies on the risk of mercury (Hg) in Korean fishery products focus primarily on total Hg levels as opposed to methylmercury (MeHg) levels. None of the few studies on MeHg in tuna investigated tuna from Japanese restaurants. Few have evaluated lead (Pb), cadmium (Cd) and arsenic (As) in tuna. Thus, this study aimed to conduct a risk assessment by evaluating heavy metal concentrations in tuna from Japanese restaurants.

Methods

Thirty-one tuna samples were collected from Japanese restaurants in the Republic of Korea. They were classified according to region and species. The concentration of heavy metals in the samples was analyzed using the Ministry of Food and Drug Safety Food Code method. The rate of exceedance of maximum residue levels (MRLs) and the risk compared to the provisional tolerable weekly intake (PTWI) set by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (%PTWI) were evaluated for risk assessment.

Results

The mean of MeHg, Pb, Cd and As concentrations were 0.56 ± 1.47 mg/kg, 33.95 ± 3.74 μg/kg, 14.25 ± 2.19 μg/kg and 1.46 ± 1.89 mg/kg, respectively. No sample exceeded the MRLs of Pb and Cd, but 9.7% of the samples exceeded the MRL of MeHg. The %PTWIs of MeHg, Pb, Cd and As were 4.2037, 0.0162, 0.0244 and 1.1627, respectively. The %PTWI of MeHg by age group and sex was highest among men aged 19-29 years (10.6494), followed by men aged 30-49 years (7.2458) and women aged 19-29 years (4.8307).

Conclusions

We found that 3 out of 31 samples exceeded the MRL of MeHg. The %PTWI of MeHg showed significant differences based on age and sex, and the value was likely to exceed a safe level depending on individuals' eating behaviors. Therefore, improved risk management for MeHg is required.

Patterns of Antinuclear Antibodies in a New Variant of Endemic Pemphigus in El Bagre, Colombia, Colocalizing with Antigens against MIZAP, ARVCF, p0071, and Desmoplakins I and II

BACKGROUND

A new variant of endemic pemphigus foliaceus (EPF) has been documented, El Bagre-EPF. We aimed to study antinuclear antibodies (ANAs) in these patients.

METHODS

We performed a case-control study, testing 57 patients affected by this disease and 57 controls from the endemic area matched by work activity and demographics. The participants were evaluated clinically as well as by detection of ANAs utilizing HEp-2 cells. We utilized Triton-induced partial permeabilization of the cell membranes, allowing for the visualization of intracellular and intranuclear antigens. We also immunoadsorbed the ANAs using synthetic peptides to elucidate the nature of the ANA.

RESULTS

We detected the presence of a new pattern of ANAs. The new pattern of ANAs was seen in 24% of the El Bagre-EPF patients, compared to our controls (P < 0.001). The new ANA pattern consisted of a thin nuclear and nucleolar rim, finely speckled nucleolar, nuclear membrane pores stains, and a positive intranuclear stain directed against small nuclear components, as well as cytoplasmic deposits of autoantibodies were also observed. The new ANAs pattern perfectly colocalized with commercial antibodies to miocardium-enriched zonula occlusans-1 associated protein (MIZAP), armadillo repeat gene deleted in velo-cardio-facial syndrome (ARVCF), p0071 and desmoplakins I-II (all from Progen Biotechnik). Additionally in 14% of patients with El Bagre-EPF forme fruste and hyperpigmented clinical presentations, a classic homogeneous ANA pattern was observed with autoantibodies specific for Ro, La, Sm, and double-stranded DNA antigens. Immunoadsorption with peptide-based sequences from MIZAP, ARVCF, p0071 and desmoplakins I-II removed the new ANA pattern.

CONCLUSIONS

We describe a new pattern of ANAs in El Bagre-EPF, colocalizing with autoantibodies directed against MIZAP, ARVCF, p0071, and desmoplakins I-II.

Mercury exposure, neopterin profile, and tryptophan degradation in dental technicians

Amalgam has been widely used as a restorative dental material for over 150 years. Most standard dental amalgam formulations contain approximately 50% elemental mercury in a mixture of copper, tin, silver, and zinc. Mercury is a highly volatile metal, which can easily vaporize to a colorless and odorless gas. It has been demonstrated that mercury is released from dental amalgam, which is increased by chewing, eating, brushing, and drinking hot liquids. Besides this, amalgam is the main occupational exposure source of mercury for dental workers. It is known that mercury exposure causes immune modulation in humans. In this study, it was aimed to evaluate the changes in neopterin levels and tryptophan (Trp) degradation in dental technicians. It was observed that low levels of occupational mercury exposure resulted in decreased neopterin, kynurenine (Kyn), and Kyn/Trp levels. Moreover, mercury and neopterin levels had a significant positive correlation in workers. The lower neopterin levels and Kyn/Trp in dental technicians compared to an unexposed group indicates a possible immune suppression with low level of occupational mercury exposure during amalgam preparation. The relationship between urinary mercury levels as an indicator of occupational mercury exposure and neopterin reminded an effect on T-cell-mediated immune response.

A Bibliometric Analysis of the Scientific Research on Artisanal and Small-Scale Mining

Mineral resource exploitation is one of the activities that contribute to economic growth and the development of society. Artisanal and small-scale mining (ASM) is one of these activities. Unfortunately, there is no clear consensus to define ASM. However, its importance is relevant in that it represents, in some cases, the only employment alternative for millions of people, although it also significantly impacts the environment. This work aims to investigate the scientific information related to ASM through a bibliometric analysis and, in addition, to define the new lines that are tending to this field. The study comprises three phases of work: (i) data collection, (ii) data processing and software selection, and (iii) data interpretation. The results reflect that the study on ASM developed intensively from 2010 to the present. In general terms, the research addressed focuses on four interrelated lines: (i) social conditioning factors of ASM, (ii) environmental impacts generated by ASM, (iii) mercury contamination and its implication on health and the environment, and (iv) ASM as a livelihood. The work also defines that geotourism in artisanal mining areas is a significant trend of the last decade, explicitly focusing on the conservation and use of the geological and mining heritage and, in addition, the promotion of sustainable development of ASM.

Serum cytokines are associated with n-3 polyunsaturated fatty acids and not with methylmercury measured in infant cord blood in the Seychelles child development study

BACKGROUND

Maternal fish consumption increases infant methylmercury (MeHg) exposure and polyunsaturated fatty acid (PUFA) concentrations. The n-3 PUFA are regulators of inflammation while MeHg may impact the cord cytokine profile and, subsequently, contribute to immune mediated outcomes. This study aimed to investigate associations between infant MeHg exposure and cord cytokine concentrations while adjusting for cord PUFA.

METHODS

We studied participants in the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2), a large birth cohort in a high fish-eating population. Whole blood MeHg, serum PUFA and serum cytokine concentrations (IFN-γ, IL-1β, IL-2, IL-12p70, TNF-α, IL-4, IL-10, IL-13, IL-6 and IL-8) were measured in cord blood collected at delivery (n = 878). Linear regression examined associations between infant MeHg exposure and cord cytokines concentrations, with and without adjustment for cord PUFA. An interaction model examined cord MeHg, cytokines and tertiles of the n-6:n-3 ratio (low/medium/high).

RESULTS

There was no overall association between cord MeHg (34.08 ± 19.98 μg/L) and cytokine concentrations, with or without adjustment for PUFA. Increased total n-3 PUFA (DHA, EPA and ALA) was significantly associated with lower IL-10 (β = -0.667; p = 0.007) and lower total Th2 (IL-4, IL-10 and IL-13) (β = -0.715; p = 0.036). In the interaction model, MeHg and IL-1β was positive and significantly different from zero in the lowest n-6:n-3 ratio tertile (β = 0.002, p = 0.03).

CONCLUSION

Methylmercury exposure from fish consumption does not appear to impact markers of inflammation in cord blood. The association of cord n-3 PUFA with lower IL-10 and total Th2 cytokines suggests that they may have a beneficial influence on the regulation of the inflammatory milieu. These findings are important for public health advice and deserve to be investigated in follow up studies.

Potential mechanisms of some selected heavy metals in the induction of inflammation and autoimmunity

Inflammation is a physiological event that protects tissues from infection and injury. Chronic inflammation causes immune cell over activation and sustained release of inflammatory cytokines and chemokines cause pathologic conditions including autoimmune diseases. Heavy metals exposure affects innate and adaptive immune systems through triggering inflammatory responses. It seems that extended inflammatory responses could accelerate heavy metal-induced autoimmunity. In the present review we discuss the exposure route and toxicity of Cadmium (Cd), Lead (Pb), Mercury (Hg), Vanadium (V) and Platinum (Pt) and their effects on inflammatory responses by innate and adaptive immune system and autoimmunity.

[The role of mercury and arsenic in the etiology and pathogenesis of Parkinson's and Alzheimer's diseases]

A critical review of literature data on the toxic effects of mercury and arsenic on the human brain and their relationship with the etiology and pathogenesis of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases is presented. In the first case, the toxic effect of mercury and arsenic on the brain stimulates oxidative stress, which leads to the formation of free oxygen species and a decrease in the antioxidant defense of neurons. In the second case, the harmful effect of mercury changes the structure and properties of β-amyloid, and the toxic effect of arsenic contributes to its accumulation. In the pathogenesis of the diseases under consideration, particular importance is attached to the reaction of astrocytes that initiate neuroinflammation, which is also characteristic of mercury and arsenic intoxication. Considering that the symptoms recorded during intoxication with mercury and arsenic are in many respects similar to those of Parkinson's and Alzheimer's diseases, and their pathogenetic mechanisms (oxidative stress and neuroinflammation) coincide, then the toxic effects of mercury and arsenic in neurodegenerative diseases analyzed in this review can be characterized as the influence of the most significant risk factors.

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases I: Toxic Chemicals and Food

Autoimmune diseases affect 5–9% of the world’s population. It is now known that genetics play a relatively small part in the pathophysiology of autoimmune disorders in general, and that environmental factors have a greater role. In this review, we examine the role of the exposome, an individual’s lifetime exposure to external and internal factors, in the pathophysiology of autoimmune diseases. The most common of these environmental factors are toxic chemicals, food/diet, and infections. Toxic chemicals are in our food, drink, common products, the air, and even the land we walk on. Toxic chemicals can directly damage self-tissue and cause the release of autoantigens, or can bind to human tissue antigens and form neoantigens, which can provoke autoimmune response leading to autoimmunity. Other types of autoimmune responses can also be induced by toxic chemicals through various effects at the cellular and biochemical levels. The food we eat every day commonly has colorants, preservatives, or packaging-related chemical contamination. The food itself may be antigenic for susceptible individuals. The most common mechanism for food-related autoimmunity is molecular mimicry, in which the food’s molecular structure bears a similarity with the structure of one or more self-tissues. The solution is to detect the trigger, remove it from the environment or diet, then repair the damage to the individual’s body and health.

Transdisciplinary Online Health Assessment of an Artisanal and Small-Scale Gold Mining Community during the COVID-19 Pandemic in the Mandalay Region of Myanmar

Artisanal and small-scale gold mining (ASGM) has a known negative effect on the community's health; therefore, assessment to monitor community health is essential to detect any issues and enable early treatment. Because ASGM-related health issues are complex and cannot be addressed effectively with a traditional one-time health assessment alone, both long-term and regular health assessments using a transdisciplinary approach should be considered. In response to this need, we designed an online health assessment tool as a reference for a future long-term health assessment system. An online video interview was conducted with 54 respondents living in the ASGM area of Chaung Gyi Village, Thabeikkyin Township, Mandalay Region, Myanmar, via a social networking service application. The tool was used to evaluate community health during the coronavirus 2019 pandemic, including mercury intoxication symptoms, mining-related diseases, and other diseases. Results show that persons working in mining versus non-mining occupations had a greater prevalence of pulmonary diseases, such as pulmonary tuberculosis, silicosis, and bronchial asthma, in addition to malaria. Based on these findings, online health assessment using a transdisciplinary approach can be recommended as an effective tool for sustainable and long-term health assessment of ASGM-related disease and should be performed regularly following physical health surveys.

Airborne pollutants as potential triggers of systemic autoimmune rheumatic diseases: a narrative review

The pathogenesis of systemic autoimmune rheumatic diseases (SARDs) is complex and remains insufficiently understood. It is commonly accepted that both intrinsic and extrinsic environmental factors interact to induce a self-reactive immune response. Case reports and observational studies have revealed an association between SARDs and specific airborne environmental factors, but the heterogeneity of the published studies hampers clear conclusions. The aim of this review is to provide an overview of the available epidemiological evidence on the relationship between airborne pollutants and SARDs. We performed a narrative review using the PubMed database. Observational studies have shown significant associations between airborne pollutants and SARDs. Cigarette smoking is strongly associated with the development of rheumatoid arthritis (RA) while the association between cigarette smoke and the development of other SARDs remains controversial. For decades, silica exposure has been linked to systemic sclerosis (SSc), RA and systemic lupus erythematosus (SLE). There is also strong evidence for a link between solvents and SSc. Recent observations even suggest that ambient air pollution is associated with the development of SARDs. Some studies have shown associations between asbestos, organic dust, metals and pesticides and SARDs, but more studies are needed to confirm these findings. Increasing evidence has linked airborne pollutants to SARDs. Although more studies are needed to understand the potential mechanisms by which these environmental agents contribute to disease pathogenesis, awareness of the link between environmental agents and SARDs is important to recognize and prevent work-related and environmentally induced diseases.

In Utero Exposure to Mercury Is Associated With Increased Susceptibility to Liver Injury and Inflammation in Childhood

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent cause of liver disease in children. Mercury (Hg), a ubiquitous toxic metal, has been proposed as an environmental factor contributing to toxicant-associated fatty liver disease.

APPROACH AND RESULTS

We investigated the effect of prenatal exposure to Hg on childhood liver injury by combining epidemiological results from a multicenter mother-child cohort with complementary in vitro experiments on monocyte cells that are known to play a key role in liver immune homeostasis and NAFLD. We used data from 872 mothers and their children (median age, 8.1 years; interquartile range [IQR], 6.5-8.7) from the European Human Early-Life Exposome cohort. We measured Hg concentration in maternal blood during pregnancy (median, 2.0 μg/L; IQR, 1.1-3.6). We also assessed serum levels of alanine aminotransferase (ALT), a common screening tool for pediatric NAFLD, and plasma concentrations of inflammation-related cytokines in children. We found that prenatal Hg exposure was associated with a phenotype in children that was characterized by elevated ALT (≥22.1 U/L for females and ≥25.8 U/L for males) and increased concentrations of circulating IL-1β, IL-6, IL-8, and TNF-α. Consistently, inflammatory monocytes exposed in vitro to a physiologically relevant dose of Hg demonstrated significant up-regulation of genes encoding these four cytokines and increased concentrations of IL-8 and TNF-α in the supernatants.

CONCLUSIONS

These findings suggest that developmental exposure to Hg can contribute to inflammation and increased NAFLD risk in early life.

Mercury and Alzheimer's disease: a look at the links and evidence

This review paper investigates a specific environmental-disease interaction between mercury exposure and Alzheimer's disease hallmarks. Alzheimer's disease is a neurodegenerative disorder affecting predominantly the memory of the affected individual. It prevails mostly in the elderly, rendering many factors as possible causative agents, which potentially contribute to the disease pathogenicity cumulatively. Alzheimer's disease affects nearly 50 million people worldwide and is considered one the most devastating diseases not only for the patient, but also for their families and caregivers. Mercury is a common environmental toxin, found in the atmosphere mostly due to human activity, such as coal burning for heating and cooking. Natural release of mercury into the atmosphere occurs by volcanic eruptions, in the form of vapor, or weathering rocks. The most toxic form of mercury to humans is methylmercury, to which humans are exposed to by ingestion of fish. Methylmercury was found to exert its toxic effects on different parts of the human body, with predominance on the brain. There is no safe concentration for mercury in the atmosphere, even trace amounts can elicit harm to humans in the long term. Mercury's effect on Alzheimer's disease hallmarks formation, extracellular senile plaques and intracellular neurofibrillary tangles, has been widely studied. This review demonstrates the involvement of mercury, in its different forms, in the pathway of amyloid beta deposition and tau tangles formation. It aims to understand the link between mercury exposure and Alzheimer's disease so that, in the future, prevention strategies can be applied to halt the progression of this disease.

Health Studies in the Context of Artisanal and Small-Scale Mining: A Scoping Review

Artisanal and small-scale mining (ASM) is an important livelihood activity in many low- and middle-income countries. It is widely acknowledged that there are a myriad of health risk and opportunities associated with ASM. However, little is known with regard to which aspects of health have been studied in ASM settings. We conducted a scoping review of peer-reviewed publications, using readily available electronic databases (i.e., PubMed, Scopus, and Web of Science) from inception to 14 July 2020. Relevant information was synthesized with an emphasis on human and environmental exposures and health effects in a context of ASM. Our search yielded 2764 records. After systematic screening, 176 health studies from 38 countries were retained for final analysis. Most of the studies (n = 155) focused on health in ASM extracting gold. While many of the studies included the collection of environmental and human samples (n = 154), only few (n = 30) investigated infectious diseases. Little attention was given to vulnerable groups, such as women of reproductive age and children. Our scoping review provides a detailed characterisation of health studies in ASM contexts. Future research in ASM settings should address health more comprehensively, including the potential spread of infectious diseases, and effects on mental health and well-being.

Neurotoxicity of mercury: an old issue with contemporary significance

Mercury exerts a variety of toxic effects, depending on the specific compound and route of exposure. However, neurotoxicity in virtue of its consequence to health causes the greatest concern for toxicologists. This is particularly true regarding fetal development, where neurotoxic effects are much more severe than in adults, and the toxicity threshold is lower. Here, we review the major concepts regarding the neurotoxicity of mercury compounds (mercury vapor; methylmercury and ethylmercury), from exposure routes to toxicokinetic particularities leading to brain deposition and the development of neurotoxic effects. Albeit research on the neurotoxicity of mercury compounds has significantly advanced from the second half of the twentieth century onwards, several grey areas regarding the mechanism of toxicity still exist. Thus, we emphasize research advances during the last two decades concerning the molecular interactions of mercury which cause neurotoxic effects. Highlights include the disruption of glutamate signaling and excitotoxicity resulting from exposure to mercury and the interaction with redox active residues such as cysteines and selenocysteines which are the premise accounting for the disruption of redox homeostasis caused by mercurials. We also address how immunotoxic effects at the CNS, namely microglia and astrocyte activation modulate developmental neurotoxicity, a major topic in contemporary research.

Autoantibodies in outbred Swiss Webster mice following exposure to gold and mercury

Exposure to heavy metals may have toxic effects on several human organs causing morbidity and mortality. Metals may trigger or exacerbate autoimmunity in humans. Inbred mouse strains with certain H-2 haplotypes are susceptible to xenobiotic-induced autoimmunity; and their immune response to metals such as mercury, gold, and silver have been explored. Serum antinuclear antibodies (ANA), polyclonal B-cell activation, hypergammaglobulinemia and tissue immune complex deposition are the main features of metal-induced autoimmunity in inbred mice. However, inbred mouse strains do not represent the genetic heterogeneity in humans. In this study, outbred Swiss Webster (SW) mice exposed to gold or mercury salts showed immune and autoimmune responses. Intramuscular injection of 22.5 mg/kg.bw aurothiomalate (AuTM) induced IgG ANA in SW mice starting after 5 weeks that persisted until week 15 although with a lower intensity. This was accompanied by elevated serum levels of total IgG antibodies against chromatin and total histones. Exposure to gold led to development of serum IgG autoantibodies corresponding to H1 and H2A histones, and dsDNA. Both gold and mercury induced polyclonal B-cell activation. Eight mg/L mercuric chloride (HgCl₂) in drinking water, caused IgG antinucleolar antibodies (ANoA) after 5 weeks in SW mice accompanied by immune complex deposition in kidneys and spleen. Serum IgG antibodies corresponding to anti-fibrillarin, and anti-PM/Scl-100 antibodies, were observed in mercury-exposed SW mice. Gold and mercury trigger systemic autoimmune response in genetically heterogeneous outbred SW mice and suggest them as an appropriate model to study xenobiotic-induced autoimmunity.

The Relationship between Cytokine Profile and Hypertension among the Mercury-Exposed Residents of Temirtau Region in Central Kazakhstan

Background:

Mercury is a common environmental contaminant and it is also harmful to human health. Among reported toxicities, its harmful effect on hypertension is poorly documented. In Kazakhstan, Temirtau city has been reported to have a high level of mercury contamination from an acetaldehyde production factory. Therefore, we aimed to investigate the association between serum profile of cytokines and the development of hypertension among the exposed citizens.

Methods:

We selected 81 individuals for study, out of them, 41 exposed ones suffered hypertension and 40 – unexposed healthy controls in villages Chkalovo, Samarkand, Gagarinskoye, Tegiszhol, Rostovka in 2016. Mercury content in urine was studied by inversion voltammetry. Cytokine levels of IL-2, IL-6, IL-10 and TNF-α were determined by ELISA.

Results:

Mercury-exposed citizens, especially those with hypertension, had significantly higher concentrations of inflammatory cytokines TNF-α, IL-2, IL-6 and anti-inflammatory cytokine IL-10 as compared to the unexposed population. The dependence of the mercury level in urine on IL-2 content was also detected. Therefore, chronic low doses of exposure to mercury were associated with an increase in serum levels of immune markers and with the increased risk of hypertension.

Conclusion:

The presence of mercury in the body probably affected the expression of interleukin-2, one of the main cytokines that coordinate immune response.

Biomonitoring of Mercury, Cadmium and Selenium in Fish and the Population of Puerto Nariño, at the Southern Corner of the Colombian Amazon

Heavy metals threaten communities near biodiversity hotspots, as their protein sources come from the environment. This study assessed Hg, Cd, and Se concentrations in fish, as well as the magnitude of exposure and hematological conditions of adult citizens from Puerto Nariño (Colombian Amazon). Among fish samples, greater Hg concentrations were found in higher trophic level species, including Rhaphiodon vulpinus (880 ± 130 ng/g) and Pseudoplatystoma tigrinum (920 ± 87 ng/g). These species presented the highest hazard quotients and lowest Se:Hg molar ratios among those studied, showing their consumption represents a health risk to consumers. Moreover, some samples of Mylossoma duriventre and Prochilodus magdalenae had Cd levels greater than the regulated limit (100 ng/g). The average total Hg (T-Hg) concentrations in human hair and blood were 5.31 µg/g and 13.7 µg/L, respectively. All hair samples exceeded the 1.0 μg/g threshold set by the USEPA, whereas 93% of the volunteers had T-Hg blood levels greater than 5 μg/L, suggesting elevated exposure. The mean Cd level was 3.1 µg/L, with 21% of samples surpassing 5 µg/L, value at which mitigating actions should be taken. Eighty-four percent of participants presented Se deficiencies (<100 μg/L). There was a significant association between fish consumption and T-Hg in hair (ρ = 0.323; p = 0.032) and blood (ρ = 0.381; p = 0.011). In this last matrix, Se correlated with Cd content, whereas lymphocytes were inversely linked to Hg concentrations. The results of this study show that there is  extensive exposure to Hg in fish, the consumption of which may promote detrimental impacts on hematology parameters within the community.

Health Impact Assessment of Artisanal and Small-Scale Gold Mining Area in Myanmar, Mandalay Region: Preliminary Research

Increasing artisanal and small-scale gold mining (ASGM) in developing countries has raised health concerns in mining communities. A preliminary health survey was conducted in Thabeikkyin Township, Mandalay Region, Myanmar, in February 2020 to assess the health conditions of an ASGM community. Respiratory function and other clinical assessments were evaluated in miners and non-miners, and participants’ hair was analyzed for heavy metals. Respiratory function of miners was similar to that of non-miners. However, miners’ respiratory function declined with longer mining activity duration. In total, 3 out of 18 miners showed neurological signs and symptoms of chronic mercury intoxication. The median concentration of the hair mercury was significantly higher in miners than non-miners (P = 0.01), and 9 out of 18 miners and 2 out of 11 non-miners showed the warning level of mercury. We found that, despite an association between declining respiratory function and length of time mining, only a minority of miners showed clinical features of chronic mercury intoxication. Further clinical surveys with a larger sample size are necessary to determine the broader health status of this community. In addition, clinical indicators such as pulmonary function tests are recommended as additional criteria for the diagnosis of mercury intoxication.

Inflammasome/NF-κB translocation inhibition via PPARγ agonist mitigates inorganic mercury induced nephrotoxicity

Mercury (Hg) pollution poses global human health and environmental risks. However, still knowledge gaps exist on both exposures and health effects. Here, we combined transcriptome sequencing technique to further investigate the specific mechanisms of inorganic Hg toxicity in the kidney. Strikingly, transcriptomic analysis revealed that 4174 unigenes (including 2646 upregulated and 1528 downregulated unigenes) were differentially expressed under acute HgCl₂ (5 mg/kg) exposure in the kidney. Additionally, we observed that HgCl₂ selectively induced tumor necrosis factor superfamily (TNFSF) to participate in renal damage, which was consistent with the high-throughput sequencing data. The phenomenon is accompanied by NLRP3 inflammasome and NF-κB signal activation in the kidney. Simultaneously, ELISA results shown that TNF-α, IL-1β and IL-6 concentrations in the kidney were significant increased. KEGG enrichment analysis showed that peroxisome proliferators-activated receptors (PPAR) signaling pathway might be vital toxic mechanism of Hg in the kidney. Then, our data showed that PPARγ agonist (GW 1929) attenuated HgCl₂ (15 μg/ml)-induced apoptosis and NLRP3 inflammasome activation via decreasing translocation of NF-κB and increasing Bcl2 levels in vitro. Along with this, we demonstrated that PPARγ antagonists (GW9662) effectively aggravated HgCl₂-induced nephrotoxicity. Overall, our results suggested that PPARγ signaling pathway is considered to be a protective mechanism to combat against HgCl₂-triggered NLRP3 inflammasome activation and apoptosis.

Mechanisms of Environment-Induced Autoimmunity

Although numerous environmental exposures have been suggested as triggers for preclinical autoimmunity, only a few have been confidently linked to autoimmune diseases. For disease-associated exposures, the lung is a common site where chronic exposure results in cellular toxicity, tissue damage, inflammation, and fibrosis. These features are exacerbated by exposures to particulate material, which hampers clearance and degradation, thus facilitating persistent inflammation. Coincident with exposure and resulting pathological processes is the posttranslational modification of self-antigens, which, in concert with the formation of tertiary lymphoid structures containing abundant B cells, is thought to promote the generation of autoantibodies that in some instances demonstrate major histocompatibility complex restriction. Under appropriate gene-environment interactions, these responses can have diagnostic specificity. Greater insight into the molecular and cellular requirements governing this process, especially those that distinguish preclinical autoimmunity from clinical autoimmunedisease, may facilitate determination of the significance of environmental exposures in human autoimmune disease.

Urinary Metals Concentrations and Biomarkers of Autoimmunity among Navajo and Nicaraguan Men

Metals are suspected contributors of autoimmune disease among indigenous Americans. However, the association between metals exposure and biomarkers of autoimmunity is under-studied. In Nicaragua, environmental exposure to metals is also largely unexamined with regard to autoimmunity. We analyzed pooled and stratified exposure and outcome data from Navajo (n = 68) and Nicaraguan (n = 47) men of similar age and health status in order to characterize urinary concentrations of metals, compare concentrations with the US National Health and Nutrition Examination Survey (NHANES) male population, and examine the associations with biomarkers of autoimmunity. Urine samples were analyzed for metals via inductively coupled plasma mass spectrometry (ICP-MS) at the US Centers for Disease Control and Prevention. Serum samples were examined for antinuclear antibodies (ANA) at 1:160 and 1:40 dilutions, using an indirect immunofluorescence assay and for specific autoantibodies using enzyme-linked immunosorbent assay (ELISA). Logistic regression analyses evaluated associations of urinary metals with autoimmune biomarkers, adjusted for group (Navajo or Nicaraguan), age, and seafood consumption. The Nicaraguan men had higher urinary metal concentrations compared with both NHANES and the Navajo for most metals; however, tin was highest among the Navajo, and uranium was much higher in both populations compared with NHANES. Upper tertile associations with ANA positivity at the 1:160 dilution were observed for barium, cesium, lead, strontium and tungsten.

Methylmercury and long chain polyunsaturated fatty acids are associated with immune dysregulation in young adults from the Seychelles child development study

BACKGROUND

Exposure to the environmental toxicant mercury (Hg) has been associated with immune dysregulation, including autoimmune disease, but few human studies have examined methylmercury (MeHg) exposure from fish consumption.

OBJECTIVES

We examined associations between MeHg exposure and biological markers of autoimmunity and inflammation while adjusting for long chain polyunsaturated fatty acids (LCPUFA).

METHOD

At age 19 years, hair total Hg (Y19Hg), LCPUFA status, a panel of 13 antinuclear antibodies (ANA), total serum immunoglobulins (Ig) IgG, IgA, and IgM and serum markers of inflammation (IL-1, IL-2, IL-6, IL-10, C-reactive protein (CRP), IFN-γ, TNF-α) were measured in the Seychelles Child Development Study (SCDS) Main Cohort (n = 497). Multivariable regression models investigated the association between Y19Hg and biomarkers, adjusting for prenatal total hair Hg (MatHg) and other relevant covariates, and with and without adjustment for LCPUFA.

RESULTS

With each 1 ppm increase in Y19Hg (mean 10.23 (SD 6.02) ppm) we observed a 4% increased odds in a positive Combined ANA following adjustment for the n6:n3 LCPUFA ratio (β = 0.036, 95%; CI: 0.001, 0.073). IgM was negatively associated with Y19Hg (β = -0.016, 95%CI: 0.016, -0.002) in models adjusted for n-3, n-6 LCPUFA and when separately adjusted for the n-6:n-3 LCPUFA ratio. No associations were observed with MatHg. Total n-3 LCPUFA status was associated with reduced odds of a positive anti-ribonuclear protein (RNP) A. The n-3 LCPUFA were negatively associated with IL-6, IL-10, CRP, IFN-γ, TNF-α and positively with TNF-α:IL-10. There were positive associations between the n-6:n-3 ratio and IL-6, IL-10, CRP, IFN-γ, TNF-α and a negative association with TNF-α:IL-10.

DISCUSSION

The Y19Hg exposure was associated with higher ANA and lower IgM albeit only following adjustment for the n-3 LCPUFA or the n-6:n-3 LCPUFA ratio. The clinical significance of these findings is unclear, but warrant follow up at an older age to determine any relationship to the onset of autoimmune disease.

Toxicity of mercury: Molecular evidence

Minamata disease in Japan and the large-scale poisoning by methylmercury (MeHg) in Iraq caused wide public concerns about the risk emanating from mercury for human health. Nowadays, it is widely known that all forms of mercury induce toxic effects in mammals, and increasing evidence supports the concern that environmentally relevant levels of MeHg could impact normal biological functions in wildlife. The information of mechanism involved in mercurial toxicity is growing but knowledge gaps still exist between the adverse effects and mechanisms of action, especially at the molecular level. A body of data obtained from experimental studies on mechanisms of mercurial toxicity in vivo and in vitro points to that disruption of the antioxidant system may play an important role in the mercurial toxic effects. Moreover, the accumulating evidence indicates that signaling transduction, protein or/and enzyme activity, and gene regulation are involving in mediating toxic and adaptive response to mercury exposure. We conducted here a comprehensive review of mercurial toxic effects on wildlife and human, in particular synthesized key findings of molecular pathways involved in mercurial toxicity from the cells to human. We discuss the molecular evidence related mercurial toxicity to the adverse effects, with particular emphasis on the gene regulation. The further studies relying on Omic analysis connected to adverse effects and modes of action of mercury will aid in the evaluation and validation of causative relationship between health outcomes and gene expression.

Association of Fish Consumption and Mercury Exposure During Pregnancy With Metabolic Health and Inflammatory Biomarkers in Children

Importance

The balance of mercury risk and nutritional benefit from fish intake during pregnancy for the metabolic health of offspring to date is unknown.

Objective

To assess the associations of fish intake and mercury exposure during pregnancy with metabolic syndrome in children and alterations in biomarkers of inflammation in children.

Design, Setting, and Participants

This population-based prospective birth cohort study used data from studies performed in 5 European countries (France, Greece, Norway, Spain, and the UK) between April 1, 2003, and February 26, 2016, as part of the Human Early Life Exposome (HELIX) project. Mothers and their singleton offspring were followed up until the children were aged 6 to 12 years. Data were analyzed between March 1 and August 2, 2019.

Exposures

Maternal fish intake during pregnancy (measured in times per week) was assessed using validated food frequency questionnaires, and maternal mercury concentration (measured in micrograms per liter) was assessed using maternal whole blood and cord blood samples.

Main Outcomes and Measures

An aggregate metabolic syndrome score for children was calculated using the z scores of waist circumference, systolic and diastolic blood pressures, and levels of triglyceride, high-density lipoprotein cholesterol, and insulin. A higher metabolic syndrome score (score range, -4.9 to 7.5) indicated a poorer metabolic profile. Three protein panels were used to measure several cytokines and adipokines in the plasma of children.

Results

The study included 805 mothers and their singleton children. Among mothers, the mean (SD) age at cohort inclusion or delivery of their infant was 31.3 (4.6) years. A total of 400 women (49.7%) had a high educational level, and 432 women (53.7%) were multiparous. Among children, the mean (SD) age was 8.4 (1.5) years (age range, 6-12 years). A total of 453 children (56.3%) were boys, and 734 children (91.2%) were of white race/ethnicity. Fish intake consistent with health recommendations (1 to 3 times per week) during pregnancy was associated with a 1-U decrease in metabolic syndrome score in children (β = -0.96; 95% CI, -1.49 to -0.42) compared with low fish consumption (<1 time per week) after adjusting for maternal mercury levels and other covariates. No further benefit was observed with fish intake of more than 3 times per week. A higher maternal mercury concentration was independently associated with an increase in the metabolic syndrome score of their offspring (β per 2-fold increase in mercury concentration = 0.18; 95% CI, 0.01-0.34). Compared with low fish intake, moderate and high fish intake during pregnancy were associated with reduced levels of proinflammatory cytokines and adipokines in children. An integrated analysis identified a cluster of children with increased susceptibility to metabolic disease, which was characterized by low fish consumption during pregnancy, high maternal mercury levels, decreased levels of adiponectin in children, and increased levels of leptin, tumor necrosis factor α, and the cytokines interleukin 6 and interleukin 1β in children.

Conclusions and Relevance

Results of this study suggest that moderate fish intake consistent with current health recommendations during pregnancy was associated with improvements in the metabolic health of children, while high maternal mercury exposure was associated with an unfavorable metabolic profile in children.

Mercury-induced autoimmunity: Drifting from micro to macro concerns on autoimmune disorders

Mercury (Hg) is widely recognized as a neurotoxic metal, besides it can also act as a proinflammatory agent and immunostimulant, depending on individual exposure and susceptibility. Mercury exposure may arise from internal body pathways, such as via dental amalgams, preservatives in drugs and vaccines, and seafood consumption, or even from external pathways, i.e., occupational exposure, environmental pollution, and handling of metallic items and cosmetics containing Hg. In susceptible individuals, chronic low Hg exposure may trigger local and systemic inflammation, even exacerbating the already existing autoimmune response in patients with autoimmunity. Mercury exposure can trigger dysfunction of the autoimmune responses and aggravate immunotoxic effects associated with elevated serum autoantibodies titers. The purpose of the present review is to provide a critical overview of the many issues associated with Hg exposure and autoimmunity. In addition, the paper focuses on individual susceptibility and other health effects of Hg.

Hazardous heavy metals contamination of vegetables and food chain: Role of sustainable remediation approaches - A review

This review emphasizes the role of toxic metal remediation approaches due to their broad sustainability and applicability. The rapid developmental processes can incorporate a large quantity of hazardous and unseen heavy metals in all the segments of the environment, including soil, water, air and plants. The released hazardous heavy metals (HHMs) entered into the food chain and biomagnified into living beings via food and vegetable consumption and originate potentially health-threatening effects. The physical and chemical remediation approaches are restricted and localized and, mainly applied to wastewater and soils and not the plant. The nanotechnological, biotechnological and genetical approaches required to more rectification and sustainability. A cellular, molecular and nano-level understanding of the pathways and reactions are responsible for potentially toxic metals (TMs) accumulation. These approaches can enable the development of crop varieties with highly reduced concentrations of TMs in their consumable foods and vegetables. As a critical analysis by authors observed that nanoparticles could provide very high adaptability for both in-situ and ex-situ remediation of hazardous heavy metals (HHMs) in the environment. These methods could be used for the improvement of the inbuilt genetic potential and phytoremediation ability of plants by developing transgenic. These biological processes involve the transfer of gene of interest, which plays a role in hazardous metal uptake, transport, stabilization, inactivation and accumulation to increased host tolerance. This review identified that use of nanoremediation and combined biotechnological and, transgenic could help to enhance phytoremediation efficiency in a sustainable way.

Mercury Is Taken Up Selectively by Cells Involved in Joint, Bone, and Connective Tissue Disorders

Background: The causes of most arthropathies, osteoarthritis, and connective tissue disorders remain unknown, but exposure to toxic metals could play a part in their pathogenesis. Human exposure to mercury is common, so to determine whether mercury could be affecting joints, bones, and connective tissues we used a histochemical method to determine the cellular uptake of mercury in mice. Whole neonatal mice were examined since this allowed histological assessment of mercury in joint, bone, and connective tissue cells. Materials and Methods: Pregnant mice were exposed to a non-toxic dose of 0.5 mg/m3 of mercury vapor for 4 h a day on gestational days 14-18. Neonates were sacrificed at postnatal day 1, fixed in formalin, and transverse blocks of the body were processed for paraffin embedding. Seven micrometer sections were stained for inorganic mercury using silver nitrate autometallography, either alone or combined with CD44 immunostaining to detect progenitor cells. Control neonates were not exposed to mercury during gestation. Results: Uptake of mercury was marked in synovial cells, articular chondrocytes, and periosteal and tracheal cartilage cells. Mercury was seen in fibroblasts in the dermis, aorta, esophagus and striated muscle, some of which were CD44-positive progenitor cells, and in the endothelial cells of small blood vessels. Mercury was also present in renal tubules and liver periportal cells. Conclusions: Mercury is taken up selectively by cells that are predominantly affected in rheumatoid arthritis and osteoarthritis. In addition, fibroblasts in several organs often involved in multisystem connective tissue disorders take up mercury. Mercury provokes the autoimmune, inflammatory, genetic, and epigenetic changes that have been described in a range of arthropathies and bone and connective tissue disorders. These findings support the hypothesis that mercury exposure could trigger some of these disorders, particularly in people with a genetic susceptibility to autoimmunity.

Heavy metals in fish and its association with autoimmunity in the development of juvenile idiopathic arthritis: a prospective birth cohort study

BACKGROUND

The etiology of Juvenile Idiopathic Arthritis (JIA) is poorly understood. The purpose of this study was to examine the possible influence of early nutrition on later development of JIA.

METHODS

In a population-based prospective birth cohort of 15,740 children we collected nutritional data, including fish consumption, and biological samples during pregnancy, at birth and at different ages. 16 years after study inclusion we identified 42 children with JIA, of whom 11 were positive for Antinuclear Antibodies (ANA). Heavy metals were analysed in cord blood of all 42 JIA patients and 40 age and sex-matched controls. A multivariable logistic regression model, adjusted for relevant factors, was used as well as Mann-Whitney U-test.

RESULTS

Fish consumption more than once a week during pregnancy as well as during the child's first year of life was associated with an increased risk of JIA (aOR 4.5 (1.95-10.4); p < 0.001 and aOR 5.1 (2.1-12.4) p < 0.001) and of ANA-positivity (aOR 2.2 (1.4-3.6); p = 0.002 and p < 0.001). Concentrations of Al, Cd, Hg and Li in cord blood were significantly higher in the JIA-group than in controls. The ANA-positive, all of whom had consumed fish >once/week their first year, had significantly higher concentrations of Al (p < 0.001), Cd (p = 0.003), and Li (p < 0.001) in cord blood than controls. Frequency of fish consumption correlated with concentrations of Cd (p = 0.003), Li (p = 0.015) and Hg (p = 0.011).

CONCLUSIONS

Moderate exposure to heavy metals, associated with fish consumption, during pregnancy and early childhood may cause effects on the immune system of the offspring, resulting in ANA positivity and JIA.

Association Between Exposure to Heavy Metals and Systemic Sclerosis: the Levels of Al, Cd, Hg, and Pb in Blood and Urine of Patients

Systemic sclerosis (SSc) is a multisystem connective tissue disease; exogenous factors-including heavy metals-may have a role in the disease pathogenesis. In this context, a study on the quantification of Al, Cd, Hg, and Pb in blood and urine of 27 SSc patients and 30 controls was carried out. Main findings were that Al was significantly depleted in blood and increased in urine of SSc patients respect to controls; and Pb was found slightly increased in blood and significantly decreased in SSc group. In addition, higher Hg levels in urine were found in SSc subjects with the higher severity of the disease. Females showed the most marked differences in the levels of blood Al, blood Pb, and urine Cd between patients and controls. Smoking, hobby, ingestion of contaminated food, job exposure may contribute to the bodily levels of Al, Hg, Pb in SSc patients. The results indicated that low, chronic, and multiple exposures to heavy metals-also through habits, diet, and environment-may influence the risk for SSc.

The Clinical Importance of the Mercury Problem in Artisanal Small-Scale Gold Mining

Artisanal small-scale mining is widely operated in various countries serving as a livelihood to many rural communities. However, it is a significant source of environmental mercury contamination which affects human health. Amalgamation and amalgam smelting, two significant steps in the artisanal small-scale mining operations generate lots of mercury vapors, leading to chronic exposure among miners. Thus, this article seeks to provide a topical review of recent findings on organ damage and metabolic disorders among mercury-exposed artisanal small-scale miners with emphasis on the contributing factors such as personal protective equipment usage and artisanal small-scale gold mining-specific occupational activities. Also, insights into the effect of mercury intoxication and mechanisms of action on organ and metabolic systems among exposed individuals are provided.

Developmental exposure to mercury chloride impairs social behavior in male offspring dependent on genetic background and maternal autoimmune environment

To date, the connection between inorganic mercury (Hg) and social behavior remains incompletely understood. The aim of this study was to investigate the influence of maternal autoimmunity by inorganic Hg (Hg²⁺) exposure on social behavior of offspring. Wild-type (WT) and immunoglobulin deficient (Ig^-/-) B10.S dams fertilized by male WT B10.S or SJL mice were treated with 50 μM Hg chloride (HgCl₂). Non-pregnant female WT B10.S mice were used to investigate factors regulating HgCl₂-induced autoimmunity to brain. HgCl₂ selectively impaired social behavior in male offspring, but not female offspring from WT B10.S dams × male SJL, in that only male offspring displayed reduced time distribution with the stranger mouse, decreased sniffing to the stranger mouse and increased self-grooming. HgCl₂ did not disrupt social behavior of male or female offspring from WT B10.S dams × male WT B10.S or Ig^-/- B10.S dams × male SJL. The offspring from WT and Ig^-/- B10.S dams × male SJL had equivalent autoimmunity to brain antigens during HgCl₂ exposure, indicating that maternal, but not offspring-derived anti-brain antibodies (Ab) impaired social behavior of the offspring. Non-pregnant WT B10.S mice treated with HgCl₂ had increased anti-brain Ab dependent on increase in CD4 T cell activation and IFNγ signaling to macrophages. IFNγ interaction with macrophages drove B cells and plasma cells to produce IgG. Therefore, HgCl₂ selectively impaired social behavior in males with certain genetic background via maternally derived anti-brain Ab production, thus providing a novel insight into our current understanding of Hg toxicity.

Insights into the Potential Role of Mercury in Alzheimer's Disease

Mercury (Hg), which is a non-essential element, is considered a highly toxic pollutant for biological systems even when present at trace levels. Elevated Hg exposure with the growing release of atmospheric pollutant Hg and rising accumulations of mono-methylmercury (highly neurotoxic) in seafood products have increased its toxic potential for humans. This review aims to highlight the potential relationship between Hg exposure and Alzheimer's disease (AD), based on the existing literature in the field. Recent reports have hypothesized that Hg exposure could increase the potential risk of developing AD. Also, AD is known as a complex neurological disorder with increased amounts of both extracellular neuritic plaques and intracellular neurofibrillary tangles, which may also be related to lifestyle and genetic variables. Research reports on AD and relationships between Hg and AD indicate that neurotransmitters such as serotonin, acetylcholine, dopamine, norepinephrine, and glutamate are dysregulated in patients with AD. Many researchers have suggested that AD patients should be evaluated for Hg exposure and toxicity. Some authors suggest further exploration of the Hg concentrations in AD patients. Dysfunctional signaling pathways in AD and Hg exposure appear to be interlinked with some driving factors such as arachidonic acid, homocysteine, dehydroepiandrosterone (DHEA) sulfate, hydrogen peroxide, glucosamine glycans, glutathione, acetyl-L carnitine, melatonin, and HDL. This evidence suggests the need for a better understanding of the relationship between AD and Hg exposure, and potential mechanisms underlying the effects of Hg exposure on regional brain functions. Also, further studies evaluating brain functions are needed to explore the long-term effects of subclinical and untreated Hg toxicity on the brain function of AD patients.

Elevated autoimmunity in residents living near abandoned uranium mine sites on the Navajo Nation

Specific autoantibodies were assessed among residents of the Navajo Nation in New Mexico chronically exposed to metal mixtures from uranium mine wastes and in drinking water supplies. Age and the extent of exposure to legacy waste from 100 abandoned uranium mine and mill sites were associated with antibodies to denatured DNA, previously known to be an early indicator of medication-induced autoimmunity. Surprisingly, autoantibodies to native DNA and/or chromatin were also linked to environmental exposure, specifically uranium consumption through drinking water for both men and women, while urinary arsenic was negatively associated with these autoantibodies in women. These findings suggest that contaminants derived from uranium mine waste enhanced development of autoantibodies in some individuals, while arsenic may be globally immunosuppressive with gender-specific effects. Specific autoantibodies may be a sensitive indicator of immune perturbation by environmental toxicants, an adverse effect not considered in current drinking water standards or regulatory risk assessment evaluations.

The relationship between mercury exposure and epigenetic alterations regarding human health, risk assessment and diagnostic strategies

BACKGROUND

Exposure to the environmental toxicants poses a serious threat to human health. The extent of exposure and the development of diseases are interrelated with each other. Chronic exposure to mercury (Hg) increases the risk of developing serious human disorders from embryo to adulthood.

OBJECTIVES

The purpose of this review is to highlight the most common human disorders induced by Hg exposure on the basis of epigenetic mechanisms. A growing body of evidence shows that Hg exposure leads to alterations in the epigenetic markers.

METHODS

We performed an organized search of the available literature using PubMed, Google Scholar, Medline, Reaxys, EMBASE and Scopus databases. All the relevant citations, including research and review articles in English were evaluated. The search terms included mercury, Hg, epigenetics, epigenetic alterations, DNA methylation, histone modifications, microRNAs (miRNAs), and risk assessment.

RESULTS

Data on human toxicity due to Hg exposure shows broad variations in terms of chemical nature, doses, and the rate of exposure. Hg consumption either via foods or environmental sources may create deleterious health effects on various physiological systems at least partially through an epigenetic mechanism.

CONCLUSION

Hg exposure could trigger epigenetic alterations, hence leading to various human disorders including reduced newborn cerebellum size, adverse behavioral outcomes, atherosclerosis and myocardial infarction. Similarly, in adults, occupational Hg exposure has been associated with an increased risk of autoimmunity. It has been revealed that miRNAs in the woman's cervix are a novel responder to maternal Hg exposure during pregnancy. Hg-induced epigenetic alterations analysis of kidney tissues showed a significant interruption in renal function. DNA methylation and histone post-translation modifications are predominant types of Hg epigenetic alterations.

Mercury-induced inflammation and autoimmunity

BACKGROUND

Human exposure to mercury leads to a variety of pathologies involving numerous organ systems including the immune system. A paucity of epidemiological studies and suitable diagnostic criteria, however, has hampered collection of sufficient data to support a causative role for mercury in autoimmune diseases. Nevertheless, there is evidence that mercury exposure in humans is linked to markers of inflammation and autoimmunity. This is supported by experimental animal model studies, which convincingly demonstrate the biological plausibility of mercury as a factor in the pathogenesis of autoimmune disease.

SCOPE OF THE REVIEW

In this review, we focus on ability of mercury to elicit inflammatory and autoimmune responses in both humans and experimental animal models.

MAJOR CONCLUSIONS

Although subtle differences exist, the inflammatory and autoimmune responses elicited by mercury exposure in humans and experimental animal models show many similarities. Proinflammatory cytokine expression, lymphoproliferation, autoantibody production, and nephropathy are common outcomes. Animal studies have revealed significant strain dependent differences in inflammation and autoimmunity suggesting genetic regulation. This has been confirmed by the requirement for individual genes as well as genome wide association studies. Importantly, many of the genes required for mercury-induced inflammation and autoimmunity are also required for idiopathic systemic autoimmunity. A notable difference is that mercury-induced autoimmunity does not require type I IFN. This observation suggests that mercury-induced autoimmunity may arise by both common and specific pathways, thereby raising the possibility of devising criteria for environmentally associated autoimmunity.

GENERAL SIGNIFICANCE

Mercury exposure likely contributes to the pathogenesis of autoimmunity.

From the Cover: Interplay Between IFN-γ and IL-6 Impacts the Inflammatory Response and Expression of Interferon-Regulated Genes in Environmental-Induced Autoimmunity

IFN-γ has been found to be robustly important to disease pathogenesis in both idiopathic and induced models of murine lupus. In transgenic mice, over production of IFN-γ in the skin results in an inflammatory response and autoimmunity. This suggests that localized exposure to environmental factors that induce autoimmunity may be associated with expression of an IFN-γ-dependent inflammatory response. Using murine mercury-induced autoimmunity (mHgIA), the severity of inflammation and proinflammatory cytokine expression, including the cellular source of IFN-γ, were assessed at the site of subcutaneous exposure and in secondary lymphoid organs. Exposure induced a localized chronic inflammation comprising both innate and adaptive immune cells but only CD8+ T and NK cells were reduced in the absence of IFN-γ. IFN-γ+ cells began to appear as early as day 1 and comprised both resident (γδ T) and infiltrating cells (CD8+ T, NKT, CD11c+). The requirements for inflammation were examined in mice deficient in genes required (Ifng, Il6) or not required (Casp1) for mHgIA. None of these genes were essential for induction of inflammation, however IFN-γ and IL-6 were required for exacerbation of other proinflammatory cytokines. Additionally, lack of IFN-γ or IL-6 impacted expression of genes regulated by either IFN-γ or type I IFN. Significantly, both IFN-γ and IL-6 were required for increased expression of IRF-1 which regulates IFN stimulated genes and is required for mHgIA. Thus IRF-1 may be at the nexus of the interplay between IFN-γ and IL-6 in exacerbating a xenobiotic-induced inflammatory response, regulation of interferon responsive genes and autoimmunity.

Modulators of mercury risk to wildlife and humans in the context of rapid global change

Environmental mercury (Hg) contamination is an urgent global health threat. The complexity of Hg in the environment can hinder accurate determination of ecological and human health risks, particularly within the context of the rapid global changes that are altering many ecological processes, socioeconomic patterns, and other factors like infectious disease incidence, which can affect Hg exposures and health outcomes. However, the success of global Hg-reduction efforts depends on accurate assessments of their effectiveness in reducing health risks. In this paper, we examine the role that key extrinsic and intrinsic drivers play on several aspects of Hg risk to humans and organisms in the environment. We do so within three key domains of ecological and human health risk. First, we examine how extrinsic global change drivers influence pathways of Hg bioaccumulation and biomagnification through food webs. Next, we describe how extrinsic socioeconomic drivers at a global scale, and intrinsic individual-level drivers, influence human Hg exposure. Finally, we address how the adverse health effects of Hg in humans and wildlife are modulated by a range of extrinsic and intrinsic drivers within the context of rapid global change. Incorporating components of these three domains into research and monitoring will facilitate a more holistic understanding of how ecological and societal drivers interact to influence Hg health risks.