Mercury as an environmental stimulus in the development of autoimmunity - A systematic review

Association of Exposure to Heavy Metal Mixtures with Systemic Immune-Inflammation Index Among US Adults in NHANES 2011-2016

In reality, people are often co-exposed to multiple heavy metals; however, current research has focused on the association between individual heavy metals and inflammation. Therefore, it is more relevant to explore the combined effects of multiple heavy metal exposure on inflammation. The study included data from the National Health and Nutrition Examination Survey (NHANES), 2011-2016. The systemic immune-inflammation index (SII) was used to reflect systemic immune-inflammation status. In this study, single variable models were used to assess the linear and non-linear relationships between single heavy metal exposures and SII. To analyze the combined effect of mixed heavy metals exposure on SII, we constructed three statistical models, including weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR). The single-exposure analysis found positive associations between multiple heavy metals and SII, while mercury in blood was negatively associated with SII, and U-shaped correlations were observed between blood lead, urine barium and strontium, and SII. In the WQS model, SII increased significantly with increasing concentrations of mixed heavy metals, while consistent results in the qgcomp model, but not statistically significant. In the BKMR model, exposure to heavy metal mixtures was positively associated with SII, with mercury, cadmium, and cobalt in urine contributing the most to the mixed exposure. In addition, synergistic and antagonistic effects between heavy metals on increasing SII were found in our study. In summary, our results reveal that combined exposure to multiple heavy metals is positively associated with SII in the US adults.

Metal mixtures and oral health among children and adolescents in the National Health and Nutrition Examination Survey (NHANES), 2017-2020

INTRODUCTION

Dental caries is the most common non-communicable human disease, yet little is known about the role of environmental metals, despite teeth consisting of a hard matrix of trace elements. We conducted a cross-sectional study of associations between environmental metals and objective assessment of dental caries and subjective assessments of oral health among a representative sample of U.S. children and adolescents.

METHODS

Data were from the 2017-March 2020 pre-pandemic data file of the National Health and Nutrition Examination Survey (NHANES). To account for metal mixtures, we used weighted quantile sum (WQS) regression to estimate the joint impact of multiple trace elements assessed in blood and urine with oral disease outcomes.

RESULTS

The blood metal mixture index was associated with a 32% (95% CI: 1.11, 1.56) increased risk of decayed surfaces while the urine metal mixture index was associated with a 106%, RR (95% CI = 2.06 (1.58, 2.70) increased caries risk. For both blood and urine, Mercury (Hg) had the largest contribution to the mixture index followed by Lead (Pb). The WQS blood metal mixture index was also significantly associated with poorer self-rated oral health, although the magnitude of the association was not as strong as for the objective oral disease measures, RR (95% CI) = 1.04 (1.02, 1.07).

DISCUSSION

Increased exposure to a metal mixture was significantly related to poorer objective and subjective oral health outcomes among U.S. children and adolescents. These are among the first findings showing that metal mixtures are a significant contributor to poor oral health.

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.

Anti-Toxoplasma gondii antibodies as a risk factor for the prevalence and severity of systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by the presence of numerous autoantibodies. The interaction of infectious agents (viruses, bacteria and parasites) and a genetically susceptible host may be a key mechanism for SLE. Toxoplasma gondii is a widespread intracellular parasite that has been implicated in the pathogenesis of autoimmune diseases. However, the relationship between T. gondii infection and the increased risk of SLE in Chinese populations remains unclear.

METHODS

The seroprevalence of T. gondii infection was assessed in 1771 serum samples collected from Chinese individuals (908 healthy controls and 863 SLE patients) from different regions of China using an enzyme-linked immunosorbent assay. Serum autoantibodies and clinical information were obtained and analysed.

RESULTS

Our observations revealed a higher prevalence of anti-T. gondii antibodies (ATxA) immunoglobulin G (IgG) in serum samples from SLE patients (144/863, 16.7%) than in those from the healthy controls (53/917, 5.8%; P < 0.0001), indicating a 2.48-fold increased risk of SLE in the ATxA-IgG+ population, after adjustment for age and sex (95% confidence interval [CI] 1.70-3.62, P < 0.0001). ATxA-IgG+ SLE patients also showed a 1.75-fold higher risk of developing moderate and severe lupus symptoms (95% CI 1.14-2.70, P = 0.011) compared to ATxA-IgG- patients. Relative to ATxA-IgG- patients, ATxA-IgG+ patients were more likely to develop specific clinical symptoms, including discoid rash, oral ulcer, myalgia and alopecia. Seven antibodies, namely anti-ribosomal RNA protein (rRNP), anti-double stranded DNA (dsDNA), anti-cell membrane DNA (cmDNA), anti-scleroderma-70 (Scl-70), anti-cardiolipin (CL), anti-beta2-glycoprotein-I (B2GPI) and rheumatoid factor (RF), occurred more frequently in ATxA-IgG+ patients. When combined with anti-dsDNA and RF/anti-rRNP/anti-cmDNA/ESR, ATxA-IgG significantly increased the risk for severe lupus.

CONCLUSIONS

Our results suggest that ATxA-IgG may be a significant risk factor for SLE prevalence and severity in Chinese populations.

Serum albumin mediates the associations between heavy metals and two novel systemic inflammation indexes among U.S. adults

BACKGROUND

The effects of heavy metal exposure on immunological function have sparked widespread concern, but unequivocal evidence on the association between mixed metal exposure and novel systemic inflammatory indexes remains scarce.

OBJECTIVES

This study aimed to analyze the associations of heavy metals with two novel systemic inflammation indexes and the mediated effects of serum albumin.

METHODS

Nineteen metals were detected among 4082 U.S. adults based on the NHANES. A linear regression, restricted cubic splines (RCS) regression, weighted quantile sum (WQS), Quantile-based Gcomputation (qgcomp), and Bayesian kernel machine regression (BKMR) were conducted to evaluate the associations of single metal and mixed metals with systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI) levels, respectively. A series of subgroup analyses were used to identify potentially vulnerable populations. Furthermore, we conducted mediation analyses to investigate the mediated effects of serum albumin on the associations of metals with SII and SIRI.

RESULTS

In the single-exposure model, exposure to various metals such as urinary Co, As, and serum Zn, Cu was associated with SII and SIRI (PFDR<0.05). Simultaneously, the above metals were linear positively correlated with SII and SIRI. Mixed-exposure analyses consistently showed that overall mixed urinary metal levels were positively pertinent for SII and SIRI levels, and the metal Co played a significant role in the urinary metal mixtures. Subgroup analyses showed that exposure to urinary Cd in men and elderly people increased SII and SIRI levels. The results of mediation analyses suggested the association of urinary metal mixture with SII and SIRI was mediated by albumin, and the proportion of mediation was 14.45% and 9.49%, respectively.

CONCLUSIONS

Our findings suggested that metal exposure is strongly associated with the levels of system inflammation indexes and that serum albumin is, in part, a mediator of this association.

Proteomic analysis of the hepatic response to a pollutant mixture in mice. The protective action of selenium

Metals and pharmaceuticals contaminate water and food worldwide, forming mixtures where they can interact to enhance their individual toxicity. Here we use a shotgun proteomic approach to evaluate the toxicity of a pollutant mixture (PM) of metals (As, Cd, Hg) and pharmaceuticals (diclofenac, flumequine) on mice liver proteostasis. These pollutants are abundant in the environment, accumulate in the food chain, and are toxic to humans primarily through oxidative damage. Thus, we also evaluated the putative antagonistic effect of low-dose dietary supplementation with the antioxidant trace element selenium. A total of 275 proteins were affected by PM treatment. Functional analyses revealed an increased abundance of proteins involved in the integrated stress response that promotes translation, the inflammatory response, carbohydrate and lipid metabolism, and the sustained expression of the antioxidative response mediated by NRF2. As a consequence, a reductive stress situation arises in the cell that inhibits the RICTOR pathway, thus activating the early stage of autophagy, impairing xenobiotic metabolism, and potentiating lipid biosynthesis and steatosis. PM exposure-induced hepato-proteostatic alterations were significantly reduced in Se supplemented mice, suggesting that the use of this trace element as a dietary supplement may at least partially ameliorate liver damage caused by exposure to environmental mixtures.

Methylmercury induces ectopic expression of complement components and apoptotic cell death in the retina of the zebrafish embryo

Methylmercury (MeHg) is a well-known neurotoxin of humans and wildlife. Visual impairments, including blindness, are frequently present in human patients with MeHg poisoning and in affected animals. It is widely assumed that MeHg-induced damage to the visual cortex is the sole or primary cause of vision loss. MeHg has been shown to accumulate in the outer segments of photoreceptor cells, and to alter the thickness of the inner nuclear layer of the fish retina. However, it is unclear whether the bioaccumulated MeHg has direct deleterious effects on the retina. Herein we report that the genes encoding complement components 5 (c5), c7a, c7b, and c9 were ectopically expressed in the inner nuclear layer of the retinas of zebrafish embryos exposed to MeHg (6-50 μg/L). The numbers of apoptotic cell deaths scored in the retinas of MeHg-treated embryos significantly increased in a concentration-dependent manner. In comparison with cadmium and arsenic, ectopic expression of c5, c7a, c7b, and c9, and the observed apoptotic cell death in the retina were specific to MeHg exposure. Our data provide evidence supporting the hypothesis that MeHg has deleterious impacts on the retinal cells, especially the inner nuclear layer. We propose that MeHg-induced retinal cell death may trigger the activation of the complement system.

EtHg is more toxic than MeHg to human peripheral blood mononuclear cells: Involvement of apoptotic, mitochondrial, oxidative and proliferative parameters

BACKGROUND

Methylmercury (MeHg) and ethylmercury (EtHg) are potent toxicants affecting the environment and human healthy. In this way, the present study aimed to investigate and compare the effects of MeHg and EtHg exposure on human peripheral blood mononuclear cells (PBMCs), which are critical components of the mammalian immune system.

METHODS

PBMCs were exposed to 2.5 μM MeHg or 2.5 μM EtHg. The number of cells and incubation times varied according to each assay. After exposures, the PBMCs were subjected to different evaluations, including cell viability, morphological aspects, cell cycle phases, indices of apoptosis and necrosis, reactive species (RS) production, and mitochondrial functionality.

RESULTS

PBMCs exposed to EtHg were characterized by decreased viability and size, increased granularity, RS production, and apoptotic indexes accompanied by an intensification of Sub-G1 and reduction in G0-G1 cell cycle phases. Preceding these effects, we found mitochondrial dysfunctions, namely a reduction in the electron transport system related to mitochondrial complex I. In contrast, PBMCs exposed to MeHg showed only reduced viability. By ICP-MS, we found that PBMCs treated with EtHg accumulated Hg + levels ∼1.8-fold greater than MeHg-exposed cells.

CONCLUSIONS AND SIGNIFICANCE

Taken together, our findings provide important insights about mercury immunotoxicity, showing that EtHg is more immunotoxic to human PBMCs than MeHg.

Origin, dietary exposure, and toxicity of endocrine-disrupting food chemical contaminants: A comprehensive review

Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.

Mercury-associated neural epidermal growth factor-like 1 protein (NELL-1) positive membranous nephropathy after use of skin lightening creams

INTRODUCTION

Membranous nephropathy, one of the common causes of glomerulonephritis worldwide, is reported in association with mercury exposure. Neural epidermal growth factor-like 1 protein is a recently described target antigen in membranous nephropathy.

CASE SERIES

Three woman (ages 17, 39, and 19 years old) presented sequentially for our evaluation with complaints consistent with nephrotic syndrome. All three had nephrotic range proteinuria, hypoalbuminemia, hypercholesterolemia, hypothyroidism, and inactive urinary sediments. Kidney biopsies were performed in the first two patients, which demonstrated findings consistent with membranous nephropathy and positive staining for neural epidermal growth factor-like 1 protein. On discovery that they were all using the same skin-lightening cream, samples of the cream were tested and found to contain between 2,180 parts per million and 7,698 parts per million of mercury. Elevated urine and blood mercury concentrations were also found in the first two patients. All three patients improved following cessation of use and treatment with levothyroxine (all three patients) and corticosteroids and cyclophosphamide in patients one and two.

DISCUSSION

We hypothesize the role of autoimmunity triggered by mercury exposure in the pathogenesis of neural epidermal growth factor-like 1 protein membranous nephropathy.

CONCLUSION

Mercury exposure should be carefully assessed as a part of the evaluation of patients with neural epidermal growth factor-like 1 protein positive membranous nephropathy.

Methylmercury effects on avian brains

Methylmercury (MeHg) is a concerning contaminant due to its ubiquity and harmful effects on organisms. Although birds are important models in the neurobiology of vocal learning and adult neuroplasticity, the neurotoxic effects of MeHg are less understood in birds than mammals. We surveyed the literature on MeHg effects on biochemical changes in the avian brain. Publication rates of papers related to neurology and/or birds and/or MeHg increased with time and can be linked with historical events, regulations, and increased understanding of MeHg cycling in the environment. However, publications on MeHg effects on the avian brain remain relatively low across time. The neural effects measured to evaluate MeHg neurotoxicity in birds changed with time and researcher interest. The measures most consistently affected by MeHg exposure in birds were markers of oxidative stress. NMDA, acetylcholinesterase, and Purkinje cells also seem sensitive to some extent. MeHg exposure has the potential to affect most neurotransmitter systems but more studies are needed for validation in birds. We also review the main mechanisms of MeHg-induced neurotoxicity in mammals and compare it to what is known in birds. The literature on MeHg effects on the avian brain is limited, preventing full construction of an adverse outcome pathway. We identify research gaps for taxonomic groups such as songbirds, and age- and life-stage groups such as immature fledgling stage and adult non-reproductive life stage. In addition, results are often inconsistent between experimental and field studies. We conclude that future neurotoxicological studies of MeHg impacts on birds need to better connect the numerous aspects of exposure from molecular physiological effects to behavioural outcomes that would be ecologically or biologically relevant for birds, especially under challenging conditions.

Aggregation-Induced Emission Luminogen-Encapsulated Fluorescent Hydrogels Enable Rapid and Sensitive Quantitative Detection of Mercury Ions

Hg²⁺ contamination in sewage can accumulate in the human body through the food chains and cause health problems. Herein, a novel aggregation-induced emission luminogen (AIEgen)-encapsulated hydrogel probe for ultrasensitive detection of Hg²⁺ was developed by integrating hydrophobic AIEgens into hydrophilic hydrogels. The working mechanism of the multi-fluorophore AIEgens (TPE-RB) is based on the dark through-bond energy transfer strategy, by which the energy of the dark tetraphenylethene (TPE) derivative is completely transferred to the rhodamine-B derivative (RB), thus resulting in intense photoluminescent intensity. The spatial networks of the supporting hydrogels further provide fixing sites for the hydrophobic AIEgens to enlarge accessible reaction surface for hydrosoluble Hg²⁺, as well create a confined reaction space to facilitate the interaction between the AIEgens and the Hg²⁺. In addition, the abundant hydrogen bonds of hydrogels further promote the Hg²⁺ adsorption, which significantly improves the sensitivity. The integrated TPE-RB-encapsulated hydrogels (TR hydrogels) present excellent specificity, accuracy and precision in Hg²⁺ detection in real-world water samples, with a 4-fold higher sensitivity compared to that of pure AIEgen probes. The as-developed TR hydrogel-based chemosensor holds promising potential as a robust, fast and effective bifunctional platform for the sensitive detection of Hg²⁺.

Benzo[a]pyrene Exposure Reduces Cell-Type Diversity and Stimulates Sex-Biased Damage Pathways in End Organs of Lupus-Prone Mice

Studies indicate that genetic factors only account for approximately thirty percent of all autoimmune diseases, while the rest of autoimmune pathogenesis is attributed to environmental factors including toxic chemicals. To understand if and how environmental pollutants trigger autoimmunity, we investigated the effect of benzo[a]pyrene (BaP) exposure on the development of autoimmune phenotypes in the lupus-prone MRL strain. The exposure of MRL mice to BaP over the course of 8 weeks before lupus onset resulted in total body weight loss in males, while marginal changes in anti-dsDNA levels occurred. Multi-organ analyses of BaP-treated and control MRL mice suggested that the kidney is a major organ directly affected by the metabolism of benzene-containing compounds, with increased expression of BaP-target genes including Cyp4b1 and Hao2. Intriguingly, spatial transcriptomic data showed that BaP caused a drastic reduction in cell-type diversity in both the kidneys and spleen of MRL mice. Further analysis of the molecular pathways affected suggested a sex-biased effect of BaP treatment, with the upregulated expression of angiogenesis genes in the lungs and an increased deposition of C3 in the kidneys of male mice. While SLE is more common in women, the disease is more severe in male patients, with an increased risk of disease progression to renal failure and lung cancer. Our results reveal sex-biased molecular pathways stimulated by BaP which may help explain the increased likelihood of end organ damage in males with lupus.

Sample Preparation and Analytical Techniques in the Determination of Trace Elements in Food: A Review

Every human being needs around 20 essential elements to maintain proper physiological processes. However, trace elements are classified as beneficial, essential, or toxic for living organisms. Some trace elements are considered essential elements for the human body in adequate quantities (dietary reference intakes, DRIs), while others have undetermined biological functions and are considered undesirable substances or contaminants. Pollution with trace elements is becoming a great concern since they can affect biological functions or accumulate in organs, causing adverse effects and illnesses such as cancer. These pollutants are being discarded in our soils, waters, and the food supply chain due to several anthropogenic factors. This review mainly aims to provide a clear overview of the commonly used methods and techniques in the trace element analysis of food from sample preparations, namely, ashing techniques, separation/extraction methods, and analytical techniques. Ashing is the first step in trace element analysis. Dry ashing or wet digestion using strong acids at high pressure in closed vessels are used to eliminate the organic matter. Separation and pre-concentration of elements is usually needed before proceeding with the analytical techniques to eliminate the interferences and ameliorate the detection limits.

Long-range transport of atmospheric speciated mercury from the eastern waters of Taiwan Island to northern South China Sea

This study explored the temporospatial distribution, gas-particle partition, and pollution sources of atmospheric speciated mercury (ASM) from the eastern offshore waters of the Taiwan Island (TI) to the northern South China Sea (SCS). Both gaseous and particulate mercury were simultaneously sampled at three remote sites in four seasons. The average concentrations of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate bound mercury (PBM) were 2.05 ± 0.45 ng/m³, 19.17 ± 5.39 pg/m³, and 0.11 ± 0.06 ng/m³, respectively. The concentrations of GEM and PBM in the cold seasons were higher than those in the warm seasons, but those of GOM had an opposite trend. In terms of gas-solid partition, ASM was apportioned as 91.3-97.3% of GEM and 2.7-8.7% of GOM and PBM. The average concentrations of GEM, GOM, and PBM at the Green Island (GI) were 2.21 ± 0.47 ng/m³, 22.31 ± 5.35 pg/m³, and 0.12 ± 0.06 ng/m³; those at the Kenting Peninsula (KT) were 2.11 ± 0.43 ng/m³, 20.57 ± 4.38 pg/m³, and 0.11 ± 0.06 ng/m³; and those at the Dongsha Islands (DS) were 1.84 ± 0.40 ng/m³, 15.19 ± 3.58 pg/m³, and 0.08 ± 0.05 ng/m³, respectively. Overall, the spatial distribution of ASM concentrations showed the order as: GI > KT > DS. Air masses blown mainly from the West Pacific Ocean (WPO) and SCS in summer showed the lowest ASM concentrations. Oppositely, high ASM concentrations were commonly observed in spring and winter when polluted air masses were blown by Asian Northeastern Monsoons (ANMs). The transport routes of polluted air masses were originated mainly from North China, Central China, Northeast China, Korea and Japan, and mostly passed through the urban and industrial regions in the northeastern Asian countries.

Dental caries and risk of newly-onset systemic lupus erythematosus: a nationwide population-based cohort study

OBJECTIVE

This study investigated whether patients with history of dental caries are associated with an increased risk of newly-onset systemic lupus erythematosus (SLE).

METHODS

A total of 501,461 carious patients and 258,918 controls without carious teeth were enrolled between 1997 and 2013 from the National Health Insurance Research Database. Subgroup analyses were conducted based on restorative materials including amalgam, composite resins, or both. The cumulative incidence and hazard ratios (HRs) of SLE development were derived after adjusting for age, sex, socioeconomic status, income, insured classification, comorbidities, and frequency of dental visit in a multivariable model.

RESULTS

The risk of SLE was significantly higher in carious patients (HR = 1.98, 95% confidence interval [CI] = 1.65-2.38) compared to controls. Dose-dependent relationship between caries and risk of SLE was identified. The risk of SLE was higher among those who had dental visits ≧11 (HR = 2.53, 95% CI = 1.86-3.43), followed by those with 3-10 dental visits (HR = 1.86, 95% CI = 1.36-2.54), when compared to those with 1-2 visits, and was higher among those who had carious teeth extractions ≧5 (HR = 1.88, 95% CI = 1.19-2.97), followed by those with 1-4 carious teeth extractions (HR = 1.36, 95% CI = 1.17-1.59) than those without extraction. The risk of SLE for dental caries management among different restorative materials, including amalgam, composite resins, or both, was not statistically different.

CONCLUSIONS

Patients with dental caries were associated with higher SLE risks. The relationship between dental caries and risk of SLE was dose-dependent, regardless of the material used for the restoration.

Mercury Contamination in Fish and Its Effects on the Health of Pregnant Women and Their Fetuses, and Guidance for Fish Consumption-A Narrative Review

As a principal source of long-chain omega-3 fatty acids (3FAs), which provide vital health benefits, fish consumption also comes with the additional benefit of being rich in diverse nutrients (e.g., vitamins and selenium, high in proteins and low in saturated fats, etc.). The consumption of fish and other seafood products has been significantly promoted universally, given that fish is an important part of a healthy diet. However, many documents indicate that fish may also be a potential source of exposure to chemical pollutants, especially mercury (Hg) (one of the top ten chemicals or groups of chemicals of concern worldwide), and this is a grave concern for many consumers, especially pregnant women, as this could affect their fetuses. In this review, the definition of Hg and its forms and mode of entrance into fish are introduced in detail and, moreover, the bio-accumulation of Hg in fish and its toxicity and action mechanisms on fish and humans, especially considering the health of pregnant women and their fetuses after the daily intake of fish, are also reviewed. Finally, some feasible and constructive suggestions and guidelines are recommended for the specific group of pregnant women for the consumption of balanced and appropriate fish diets in a rational manner.

Dietary Selenomethionine Reduce Mercury Tissue Levels and Modulate Methylmercury Induced Proteomic and Transcriptomic Alterations in Hippocampi of Adolescent BALB/c Mice

Methylmercury (MeHg) is a well-known environmental contaminant, particularly harmful to the developing brain. The main human dietary exposure to MeHg occurs through seafood consumption. However, seafood also contains several nutrients, including selenium, which has been shown to interact with MeHg and potentially ameliorate its toxicity. The aim of this study was to investigate the combined effects of selenium (as selenomethionine; SeMet) and MeHg on mercury accumulation in tissues and the effects concomitant dietary exposure of these compounds exert on the hippocampal proteome and transcriptome in mice. Adolescent male BALB/c mice were exposed to SeMet and two different doses of MeHg through their diet for 11 weeks. Organs, including the brain, were sampled for mercury analyses. Hippocampi were collected and analyzed using proteomics and transcriptomics followed by multi-omics bioinformatics data analysis. The dietary presence of SeMet reduced the amount of mercury in several organs, including the brain. Proteomic and RNA-seq analyses showed that both protein and RNA expression patterns were inversely regulated in mice receiving SeMet together with MeHg compared to MeHg alone. Several pathways, proteins and RNA transcripts involved in conditions such as immune responses and inflammation, oxidative stress, cell plasticity and Alzheimer’s disease were affected inversely by SeMet and MeHg, indicating that SeMet can ameliorate several toxic effects of MeHg in mice.

Immunomodulation, Toxicity, and Therapeutic Potential of Nanoparticles

Altered immune responses associated with human disease conditions, such as inflammatory and infectious diseases, cancers, and autoimmune diseases, are among the primary causes of morbidity across the world. A wealth of studies has demonstrated the efficiency of nanoparticles (NPs)-based immunotherapy strategies in different laboratory model systems. Nanoscale dimensions (<100 nm) enable NPs to have increased surface area to volume ratio, surface charge, and reactivity. Physicochemical properties along with the shapes, sizes, and elasticity influence the immunomodulatory response induced by NPs. In recent years, NPs-based immunotherapy strategies have attained significant focus in the context of cancers and autoimmune diseases. This rapidly growing field of nanomedicine has already introduced ~50 nanotherapeutics in clinical practices. Parallel to wide industrial applications of NPs, studies have raised concerns about their potential threat to the environment and human health. In past decades, a wealth of in vivo and in vitro studies has demonstrated the immunotoxicity potential of various NPs. Given that the number of engineered/designed NPs in biomedical applications is continuing to increase, it is pertinent to establish the toxicity profile for their safe and intelligent use in biomedical applications. The review is intended to summarize the NPs-induced immunomodulation pertaining to toxicity and therapeutic development in human health.

Non-destructive mercury exposure assessment in the Brandt's hedgehog (Paraechinus hypomelas): spines as indicators of endogenous concentrations

Due to its persistence, bioaccumulation characteristics, and toxicity, environmental contamination with mercury (Hg) is of high concern for human health, living organisms, and ecosystems, and its biological monitoring is highly relevant. In this study, the levels of total Hg were measured in organs, tissues, and spines of 50 individuals of Brandt's hedgehog collected in Iran in 2019. The Hg median levels in kidneys, liver, muscle, and spines were 156, 47, 47, and 20 ng/g dry weight, respectively. The results showed a significant positive correlation between the levels of Hg in kidneys and liver (r = 0.519; p < 0.01) and in spines and muscle (r = 0.337, p < 0.01) and kidneys (r = 0.309, p < 0.05). Significant differences (p < 0.05) in Hg levels in organs and tissues were also observed depending on the sex, weight, length, and age of the individuals. In addition, the median levels of total Hg in kidneys of Brandt's hedgehogs from an agricultural ecotype (median 190 ± 65) were significantly higher (p < 0.05) than those collected from a forest ecotype (median 126 ± 50), suggesting that the habitat could have a significant impact on animal contamination.

How Do Different Physical Stressors' Affect the Mercury Release from Dental Amalgam Fillings and Microleakage? A Systematic Review

BACKGROUND

Approximately 50% of dental amalgam is elemental mercury by weight. Accumulating body of evidence now shows that not only static magnetic fields (SMF) but both ionizing and non-ionizing electromagnetic radiations can increase the rate of mercury release from dental amalgam fillings. Iranian scientists firstly addressed this issue in 2008 but more than 10 years later, it became viral worldwide.

OBJECTIVE

This review was aimed at evaluating available data on the magnitude of the effects of different physical stressors (excluding chewing and brushing) on the release of toxic mercury from dental amalgam fillings and microleakage.

MATERIAL AND METHODS

The papers reviewed in this study were searched from PubMed, Google Scholar, and Scopus (up to 1 December 2019). The keywords were identified from our initial research matching them with those existing on the database of Medical Subject Headings (MeSH). The non-English papers and other types of articles were not included in this review.

RESULTS

Our review shows that exposure to static magnetic fields (SMF) such as those generated by MRI, electromagnetic fields (EMF) such as those produced by mobile phones; ionizing electromagnetic radiations such as X-rays and non- Ionizing electromagnetic radiation such as lasers and light cure devices can significantly increase the release of mercury from dental amalgam restorations and/or cause microleakage.

CONCLUSION

The results of this review show that a wide variety of physical stressors ranging from non-ionizing electromagnetic fields to ionizing radiations can significantly accelerate the release of mercury from amalgam and cause microleakage.

Effect of inorganic mercury exposure on reproductive system of male mice: Immunosuppression and fibrosis in testis

Mercury as a toxic heavy metal will accumulate in the body and induce various diseases through the food chain. However, it is unknown that the detailed mechanism of reproductive disorder induced by inorganic mercury in male mice to date. This study investigated the toxicological effect of mercuric chloride (HgCl₂ ) exposure on reproductive system in male mice. Male Kunming mice received normal saline daily or HgCl₂ (3 mg/kg bodyweight) by intraperitoneal injection for a week. The reproductive function was evaluated, and the HgCl₂ exposure induced the decline of sperm quality, pregnancy rate, mean litter size, and survival rate. Notably, we firstly found the HgCl₂ -induced immunosuppression and fibrosis in mice testis according to the results of RNA sequencing. Collectively, these findings demonstrate that HgCl₂ exposure disrupts the reproductive system and induces testicular immunosuppression and fibrosis via inhibition of the CD74 signaling pathway in male mice.

Electrochemical detection of mercuric(ii) ions in aqueous media using glassy carbon electrode modified with synthesized tribenzamides and silver nanoparticles

This study reports the synthesis, characterization, and mercuric ion detection ability of novel tribenzamides having flexible and rigid moieties.

Fish and the Thyroid: A Janus Bifrons Relationship Caused by Pollutants and the Omega-3 Polyunsaturated Fatty Acids

Benefits of the omega-3 polyunsaturated fatty acids (PUFA) on a number of clinical disorders, including autoimmune diseases, are widely reported in the literature. One major dietary source of PUFA are fish, particularly the small oily fish, like anchovy, sardine, mackerel and others. Unfortunately, fish (particularly the large, top-predator fish like swordfish) are also a source of pollutants, including the heavy metals. One relevant heavy metal is mercury, a known environmental trigger of autoimmunity that is measurable inside the thyroid. There are a number of interactions between the omega-3 PUFA and thyroid hormones, even at the level of the thyroid hormone transport proteins. Concerning the mechanisms behind the protection from/amelioration of autoimmune diseases, including thyroiditis, that are caused by the omega-3 PUFA, one can be the decreased production of chemokines, a decrease that was reported in the literature for other nutraceuticals. Recent studies point also to the involvement of resolvins. The intracellular increase in resolvins is associated with the tissue protection from inflammation that was observed in experimental animals after coadministration of omega-3 PUFA and thyroid hormone. After having presented data on fish consumption at the beginning, we conclude our review by presenting data on the market of the dietary supplements/nutraceuticals. The global omega-3 products market was valued at USD 2.10 billion in 2020, and was projected to go up at a compound annual growth rate of 7.8% from 2020 to 2028. Among supplements, fish oils, which are derived mainly from anchovies, are considered the best and generally safest source of omega-3. Taking into account (i) the anti-autoimmunity and anti-cancer properties of the omega-3 PUFA, (ii) the increasing incidence of both autoimmune thyroiditis and thyroid cancer worldwide, (iii) the predisposing role for thyroid cancer exerted by autoimmune thyroiditis, and (iv) the risk for developing metabolic and cardiovascular disorders conferred by both elevated/trendwise elevated serum TSH levels and thyroid autoimmunity, then there is enough rationale for the omega-3 PUFA as measures to contrast the appearance and/or duration of Hashimoto's thyroiditis as well as to correct the slightly elevated serum TSH levels of subclinical hypothyroidism.

Gut Microbiota-Modulated Metabolomic Profiling Shapes the Etiology and Pathogenesis of Autoimmune Diseases

Autoimmunity is a complex and multifaceted process that contributes to widespread functional decline that affects multiple organs and tissues. The pandemic of autoimmune diseases, which are a global health concern, augments in both the prevalence and incidence of autoimmune diseases, including type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. The development of autoimmune diseases is phenotypically associated with gut microbiota-modulated features at the molecular and cellular levels. The etiology and pathogenesis of autoimmune diseases comprise the alterations of immune systems with the innate and adaptive immune cell infiltration into specific organs and the augmented production of proinflammatory cytokines stimulated by commensal microbiota. However, the relative importance and mechanistic interrelationships between the gut microbial community and the immune system during progression of autoimmune diseases are still not well understood. In this review, we describe studies on the profiling of gut microbial signatures for the modulation of immunological homeostasis in multiple inflammatory diseases, elucidate their critical roles in the etiology and pathogenesis of autoimmune diseases, and discuss the implications of these findings for these disorders. Targeting intestinal microbiome and its metabolomic associations with the phenotype of autoimmunity will enable the progress of developing new therapeutic strategies to counteract microorganism-related immune dysfunction in these autoimmune diseases.

The Antioxidant Efficacy of Wheatgrass (Triticum Aestivum) on Mercuric Chloride (HgCl2) - Induced Oxidative Stress in Rat Model

Mercury is a harmful toxic pollutant, which has hepato-nephrotoxic, hematotoxic, genotoxic and neurotoxic, effects. The aim of the study was to evaluate the protective efficacy of wheatgrass on mercuric chloride (HgCl2) induced oxidative stress and associated complications in rat model. Albino rats were divided into four groups (three rats per group). Group I normal control group. Group II oxidative stressed group received mercuric chloride (0.5 mg/kg/day). Group III only received wheatgrass extract (100 mg/kg/day), whereas Group IV received wheatgrass (100 mg/kg/day) after one hour, followed by mercuric chloride (0.5 mg/kg/day) for 30 days. The results of the study showed that wheatgrass supplementation significantly decreased the HgCl2 induced elevated oxidative stress parameters Plasma Malondialdehyde (MDA) content, Plasma membrane redox system (PMRS), Advanced oxidation protein products (AOPP), simultaneously elevated lipid profile (Total Cholesterol, Triglycerides, Low-density lipoprotein (LDL), liver enzymes as, Plasma Alkaline phosphatase (ALP), Aspartate aminotransferase (AST), and Alanine aminotransferase (ALT), Serum Urea, and Creatinine levels in rats. In addition, wheatgrass treatment improved the antioxidant status in terms of intracellular Reduced Glutathione (GSH), Ferric reducing antioxidant power (FRAP) and 2, 2- diphenyl -1- picrylhydrazyl (DPPH). Therefore it can be concluded that wheatgrass has great potential to diminish the stress-mediated complications and improve the antioxidant status.

Chronological Trends and Mercury Bioaccumulation in an Aquatic Semiarid Ecosystem under a Global Climate Change Scenario in the Northeastern Coast of Brazil

Simple Summary

Managing aquatic systems is becoming increasingly complex due to human impacts, multiple and competing water needs and climate variability. Considering the Hg concentration present in the top layers of sediment (~20 cm around 30 to 40 years) with the outer layers in the tree cores tree rings cores and in the sediment’s cores from Pacoti estuary and the Ceará estuary, overall data indicate an increase in mercury in recent years. A positive and significant correlation (p < 0.05) was revealed between Hg trends in sediments and Hg trends in annular tree rings. This shared Hg pattern reflects local environmental conditions. The results of this work reinforce the indicators previously described in the semiarid NE region of Brazil, showing that global climate change and some anthropogenic factors are key drivers to Hg exposure and biomagnification for wildlife and humans. Possible climate-induced shifts in these aquatic systems highlight the need for accurate and regionally specific metrics of change in the past in response to climate and for improved understanding of response to climate factors. These processes are inducing a greater mobilization of bioavailable Hg, which could allow an acceleration of the biogeochemical transformation of Hg.

Abstract

Due to global warming, in the northeastern semiarid coastal regions of Brazil, regional and global drivers are responsible for decreasing continental runoff and increasing estuarine water residence time, which promotes a greater mobilization of bioavailable mercury (Hg) and allows increasing fluxes and/or bioavailability of this toxic trace element and an acceleration of biogeochemical transformation of Hg. In this work, an application of dendrochemistry analysis (annular tree rings analysis) was developed for the reconstruction of the historical pattern of mercury contamination in a contaminated area, quantifying chronological Hg contamination trends in a tropical semiarid ecosystem (Ceará River Estuary, northeastern coast of Brazil) through registration of mercury concentration on growth rings in specimens of Rhizophora mangle L. and using the assessment in sediments as a support for the comparison of profiles of contamination. The comparison with sediments from the same place lends credibility to this type of analysis, as well as the relationship to the historical profile of contamination in the region, when compared with local data about industries and ecological situation of sampling sites. In order to evaluate the consequences of the described increase in Hg bioavailability and bioaccumulation in aquatic biota, and to assess the biological significance of Hg concentrations in sediments to fish and wildlife, muscle and liver from a bioindicator fish species, S. testudineus, were also analyzed. The results of this work reinforce the indicators previously described in the semiarid NE region of Brazil, which showed that global climate change and some anthropogenic factors are key drivers of Hg exposure and biomagnification for wildlife and humans. Considering the Hg concentration present in the top layers of sediment (~20 cm around 15 to 20 years) with the outer layers in the tree ring cores and in the sediment’s cores from Pacoti estuary and the Ceará estuary, overall the data indicate an increase in mercury in recent years in the Hg surface sediments, especially associated with the fine sediment fraction, mainly due to the increased capacity of small particles to adsorb Hg. There was revealed a positive and significant correlation (p < 0.05) between Hg trends in sediments and Hg trends in annular tree rings. This shared Hg pattern reflects local environmental conditions. The Hg concentration values in S. testudineus from both study areas are not restrictive to human consumption, being below the legislated European limit for Hg in foodstuffs. The results from S. testudineus muscles analysis suggest a significant and linear increase in Hg burden with increasing fish length, indicating that the specimens are accumulating Hg as they grow. The results from both rivers show an increase in BSAF with fish growth. The [Hg] liver/[Hg] muscles ratio >1, which indicates that the S. testudineus from both study areas are experiencing an increase in Hg bioavailability. Possible climate-induced shifts in these aquatic systems processes are inducing a greater mobilization of bioavailable Hg, which could allow an acceleration of the biogeochemical transformation of Hg.

Impacts of heavy metals and medicinal crops on ecological systems, environmental pollution, cultivation, and production processes in China

Heavy metals are widely distributed in the environment due to the natural processes and anthropogenic human activities. Their migration into no contaminated areas contributing towards pollution of the ecosystems e.g. soils, plants, water and air. It is recognized that heavy metals due to their toxicity, long persistence in nature can accumulate in the trophic chain and cause organism dysfunction. Although the popularity of herbal medicine is rapidly increasing all over the world heavy metal toxicity has a great impact and importance on herbal plants and consequently affects the quality of herbal raw materials, herbal extracts, the safety and marketability of drugs. Effective control of heavy metal content in herbal plants using in pharmaceutical and food industries has become indispensable. Therefore, this review describes various important factors such as ecological and environmental pollution, cultivation and harvest of herbal plants and manufacturing processes which effects on the quality of herbal plants and then on Chinese herbal medicines which influence human health. This review also proposes possible management strategies to recover environmental sustainability and medication safety. About 276 published studies (1988-2021) are reviewed in this paper.

A novel coumarin-based colorimetric and fluorescent probe for detecting increasing concentrations of Hg2+ in vitro and in vivo

Mercury has complex biological toxicity and can cause a variety of physiological diseases and even death, so it is of great importance to develop novel strategies for detecting trace mercury in environmental and biological samples. In this work, we designed a new coumarin-based colorimetric and fluorescent probe CNS, which could be obtained from inexpensive starting materials with high overall yield in three steps. Probe CNS could selectively respond to Hg²⁺ with obvious color and fluorescence changes, and the presence of other metal ions had no effect on the fluorescence changes. Probe CNS also exhibited high sensitivity against Hg²⁺, with a detection limit as low as 2.78 × 10^-8 M. More importantly, the behavioral tracks of zebrafish had no obvious changes upon treatment with 10 μM probe CNS, thus indicating its low toxicity. The probe showed potential application value and was successfully used for detecting Hg²⁺ in a test strip, HeLa cells and living zebrafish larvae.

Regional variations and relationships among cytokine profiles, white blood cell counts, and blood mercury concentrations in Steller sea lion (Eumetopias jubatus) pups

The Steller sea lion (SSL) population west of 144°W longitude experienced a significant population decline. While there appears to be a stable or increasing population trend in rookeries in the Gulf of Alaska (GOA) and Southeast Alaska (SEA), some rookeries within the Aleutian Islands (AI) have failed to recover. Previous studies found regional differences in whole blood total mercury concentrations ([THg]) showing more than 20% of AI pups had [THg] above critical thresholds for increased risk of immunological effects and other adverse outcomes. Measurements of immune cell-signaling proteins can be used to evaluate the immune status of marine mammals in relation to [THg]. We compared serum cytokine and chemokine concentrations in pups among regions (AI, eastern GOA, SEA), and examined associations among cytokines, chemokines, white blood cell (WBC) counts, and [THg]. Considering liver is an important target organ for mercury and immune protein synthesis we additionally examined the relationship of [THg] with liver-related enzymes serum aspartate (AST) and alanine aminotransferase (ALT). We observed regional differences in cytokine and chemokine measurements and immune protein associations. There was a positive association between total WBC counts and [THg] in AI pups, whereas a negative association between lymphocytes and [THg] in SEA pups. These findings may indicate regional variation in proliferation and differentiation of hematopoietic cells, differences in immune system development, and/or a difference in antigenic stimuli. No associations between [THg] and cytokines, chemokines, AST or ALT were found. Observed regional differences in cytokine and chemokine milieu during gestational and early development in SSL pups could lead to an imbalance in cell differentiation that could impact immunological resiliency in juvenile and adult life stages. We report concentration ranges of a suite of cytokines and chemokines which may prove to be a useful metric for ecotoxicology and risk assessment studies in SSLs and other wildlife.

RNA sequencing and proteomic profiling reveal different alterations by dietary methylmercury in the hippocampal transcriptome and proteome in BALB/c mice

Methylmercury (MeHg) is a highly neurotoxic form of mercury (Hg) present in seafood. Here, we recorded and compared proteomic and transcriptomic changes in hippocampus of male BALB/c mice exposed to two doses of MeHg. Mice were fed diets spiked with 0.28 mg MeHg kg-1, 5 mg MeHg kg-1, or an unspiked control diet for 77 days. Total mercury content was significantly (P < 0.05) increased in brain tissue of both MeHg-exposed groups (18 ± 2 mg Hg kg-1 and 0.56 ± 0.06 mg Hg kg-1). Hippocampal protein and ribonucleic acid (RNA) expression levels were significantly altered both in tissues from mice receiving a low dose MeHg (20 proteins/294 RNA transcripts) and a high dose MeHg (61 proteins/876 RNA transcripts). The majority but not all the differentially expressed features in hippocampus were dose dependent. The combined use of transcriptomic and proteomic profiling data provided insight on the influence of MeHg on neurotoxicity, energy metabolism, and oxidative stress through several regulated features and pathways, including RXR function and superoxide radical degradation.

Cadmium, lead and mercury in the blood of psoriatic and vitiligo patients and their possible associations with dietary habits

BACKGROUND

Psoriasis and vitiligo are common, autoimmune skin diseases, their etiology is still unclear. The relationship between environmental factors including diet and various skin diseases has been studied. The general mechanism of cadmium (Cd), lead (Pb) and mercury (Hg) toxicity is through the production of reactive oxygen species which are known to play a role in etiopathogenesis of skin disorders.

OBJECTIVE

The aim of this study was to estimate the influence of dietary habits on the concentration of Cd, Pb and Hg in the peripheral blood samples of patients with psoriasis and vitiligo.

METHODS

In this case-control study, sixty patients with psoriasis, fifty patients with vitiligo and fifty eight healthy people were examined. Blood levels of Cd, Pb and Hg were determined by atomic absorption spectrometry. Food-frequency questionnaires were implemented to collect the dietary data.

RESULTS

Significant differences (p < 0.05) of Cd levels were found between women and men with psoriasis and women and men in the control group. The concentration of Pb was significantly higher among vitiligo patients (50.04 ± 26.54 μg/L) than in healthy controls (36.04 ± 27.35 μg/L). Significantly lower ratio of Se/Pb, Zn/Pb and Cu/Pb was found among psoriatic men. Significantly (p < 0.05) lower values of Se/Hg ratio were observed among vitiligo patients compared to controls.

CONCLUSIONS

The elevated levels of toxic elements could increase oxidative stress which may partly contribute to inflammation in the pathogenesis of psoriasis and vitiligo, which requires further research. Analysis of the influence of frequent consumption of food products on toxic metals concentration showed that the dietary habits have impact on the content of examined toxic metals in the blood of patients. The obtained results may be useful for composing the diet and could be helpful in prevention of psoriasis and vitiligo.

[Environment and immunity-Allergies and autoimmune diseases from epidemiological perspective]

Immunity, which denotes the protection of multicellular organisms against various bacterial and viral infections, is an essential protective mechanism for living organisms. Allergy is a reaction to a foreign substance existing in the environment that is basically not a component of the self. Additionally, autoimmune diseases are associated with the dysfunction in the recognition of self and non-self, and are pathological conditions caused by immune cells attacking their own tissues and cells. In this paper, we outline the current status of immunity with respect to the environment from the epidemiological perspective with regard to the following: (1) evolution and immunity, (2) allergy, (3) autoantibodies, (4) autoimmune diseases, (5) relationships of immunity with the environment, allergy, autoantibodies, and autoimmune diseases, and (6) celiac disease.

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.

Distribution and risk of mercury in the sediments of mangroves along South China Coast

The importance of mangrove was widely reported. However, the potential risks of pollutants (e.g., Hg) accumulated in the mangroves are often ignored. Thus, the present study aimed to explore the distribution and risk of mercury (Hg) in the sediments of mangroves along South China Coast. Results showed that concentrations of total Hg ranged from 0.0815 to 0.6377 mg/kg, with an arithmetic mean value of 0.2503 mg/kg. The contamination index (P_i) showed mild pollution toxicity risks in NS, slight toxicity risks in DZG, QZ, SY, ND, GQ, TLG, and free pollutions in BMW, SJ, ZJK and BLHK. NS, DZG and SY scored the highest values of I_geo among the eleven mangrove regions studied, indicating moderate to heavy pollution inputs in these regions. As for the distribution of Hg in the sediments along tidal gradient, concentrations of Hg in the sediments sharply increased from seaward mudflat to landward mangrove, corresponding with the increases of TOC. In summary, the present data indicated that mangrove ecosystem is efficient in Hg reservoir. However, the potential ecological risks of Hg, especially in some mangrove regions easily affected by human activities, should be noted.

Seafood, wine, rice, vegetables, and other food items associated with mercury biomarkers among seafood and non-seafood consumers: NHANES 2011-2012

Fish/seafood consumption is a source of mercury; other dietary sources are not well described. This cross-sectional study used National Health and Nutrition Examination Survey (NHANES) 2011-2012 data. Participants self-reported consuming fish/seafood (N = 5427) or not (N = 1770) within the past 30 days. Whole blood total mercury (THg), methylmercury (MeHg), and urinary mercury (UHg) were determined. Diet was assessed using 24 h recall. Adjusted regression models predicted mercury biomarker concentrations with recent food consumption, while controlling for age, sex, education, and race/ethnicity. Geometric mean THg was 0.89 µg/L (95% confidence interval (CI): 0.78, 1.02) (seafood consumers) and 0.31 µg/L (95% CI: 0.28, 0.34) (non-seafood consumers); MeHg and UHg concentrations follow similar patterns. In adjusted regressions among seafood consumers, significant associations were observed between mercury biomarkers with multiple foods, including fish/seafood, wine, rice, vegetables/vegetable oil, liquor, and beans/nuts/soy. Among non-seafood consumers, higher THg was significantly associated with mixed rice dishes, vegetables/vegetable oil, liquor, and approached statistical significance with wine (p < 0.10); higher MeHg was significantly associated with wine and higher UHg was significantly associated with mixed rice dishes. Fish/seafood consumption is the strongest dietary predictor of mercury biomarker concentrations; however, consumption of wine, rice, vegetables/vegetable oil, or liquor may also contribute, especially among non-seafood consumers.

Update on Autoimmune Diseases Pathogenesis

BACKGROUND

Autoimmune diseases result from the interplay of cellular effectors like T and B cells, regulatory cells in addition to molecular factors like cytokines and regulatory molecules.

METHODS

Different electronic databases were searched in a non-systematic way to find out the literature of interest.

RESULTS

Pathogenesis of autoimmune diseases involves typical factors such as genetic background including HLA and non HLA system genes, environmental factors such as infectious agents and inflammatory cells mainly T and B lymphocytes abnormally activated leading to immune dysfunction. Other recently reported less typical factors such as micro-RNAs, circular RNAs, myeloperoxidase, vimentine and microbiome dysbiosis seem to be potential target therapies.

CONCLUSION

We aimed in this manuscript to review common factors in the pathogenesis of autoimmune diseases.

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.

Mercury-induced autoimmunity: Report of two adolescent siblings with Morvan syndrome "plus" and review of the literature

Heavy metal toxicity is a global health concern. Mercury intoxication has been implicated in the etiology and pathogenesis of autoimmune disease, including Morvan syndrome. We describe two siblings with overlapping features of distinct autoimmune syndromes following accidental exposure to elemental mercury. Morvan syndrome was the predominant clinical phenotype. In addition to the characteristic anti-leucine-rich glioma-inactivated protein 1 (LGI1) and anti-contactin-associated protein-like 2 (Caspr2) autoantibodies, glutamic acid decarboxylase 65-kilodalton isoform (GAD65), and N-type and P/Q-type voltage-gated calcium channel (VGCC) antibodies were detected. Treatment with chelation therapy, glucocorticoids, and intravenous immunoglobulin was unsuccessful, but complete resolution of symptoms was achieved following treatment with rituximab. Herein, we perform an extensive review of the literature with a focus on the emerging concepts of mercury-induced autoimmunity and the role of mercury in the etiopathogenesis of autoimmune diseases of the nervous system.

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.

Environmental Exposures and Autoimmune Diseases: Contribution of Gut Microbiome

Environmental agents have been gaining more attention in recent years for their role in the pathogenesis of autoimmune diseases (ADs). Increasing evidence has linked environmental exposures, including trichloroethene (TCE), silica, mercury, pristane, pesticides, and smoking to higher risk for ADs. However, potential mechanisms by which these environmental agents contribute to the disease pathogenesis remains largely unknown. Dysbiosis of the gut microbiome is another important environmental factor that has been linked to the onset of different ADs. Altered microbiota composition is associated with impaired intestinal barrier function and dysregulation of mucosal immune system, but it is unclear if gut dysbiosis is a causal factor or an outcome of ADs. In this review article, we first describe the recent epidemiological and mechanistic evidences linking environmental/occupational exposures with various ADs (especially SLE). Secondly, we discuss how changes in the gut microbiome composition (dysbiosis) could contribute to the disease pathogenesis, especially in response to exposure to environmental chemicals.

Human Papillomavirus Epitope Mimicry and Autoimmunity: The Molecular Truth of Peptide Sharing

OBJECTIVE

To define the cross-reactivity potential and the consequent autoimmunity intrinsic to viral versus human peptide sharing.

METHODS

Using human papillomavirus (HPV) infection/active immunization as a research model, the experimentally validated HPV L1 epitopes catalogued at the Immune Epitope DataBase were analyzed for peptide sharing with the human proteome.

RESULTS

The final data show that the totality of the immunoreactive HPV L1 epi-topes is mostly composed by peptides present in human proteins.

CONCLUSIONS

Immunologically, the high extent of peptide sharing between the HPV L1 epitopes and human proteins invites to revise the concept of the negative selection of self-reactive lymphocytes. Pathologically, the data highlight a cross-reactive potential for a spectrum of autoimmune diseases that includes ovarian failure, systemic lupus erythematosus (SLE), breast cancer and sudden death, among others. Therapeutically, analyzing already validated immunoreactive epitopes filters out the peptide sharing possibly exempt of self-reactivity, defines the effective potential for pathologic autoimmunity, and allows singling out peptide epitopes for safe immunotherapeutic protocols.

Mercury in aquatic fauna contamination: A systematic review on its dynamics and potential health risks

Mercury is an important pollutant, released into aquatic ecosystems both naturally and by anthropogenic action. This element is transferred to aquatic organisms in different ways, causing potential health risks. In addition, mercury can be accumulated by humans, especially through the consumption of contaminated food. This systematic review aims to present mercury pathways, the major routes through which this element reaches the aquatic environment and its transformations until becoming available to living animals, leading to bioaccumulation and biomagnification phenomena. The key biotic and abiotic factors affecting such processes, the impact of mercury on animal and human health and the issue of seafood consumption as a source of chronic mercury contamination are also addressed. A total of 101 articles were retrieved from a standardized search on three databases (PubMed, Emabse, and Web of Science), in addition to 28 other studies not found on these databases but considered fundamental to this review (totaling 129 articles). Both biotic and abiotic factors display fundamental importance in mediating mercurial dynamics, i.e., muscle tropism, and salinity, respectively. Consequently, mercurial contamination in aquatic environments affects animal health, especially the risk of extinction species and also on human health, with methylmercury the main mercury species responsible for acute and chronic symptomatology.