Lead (Pb) Exposure Enhances Expression of Factors Associated with Inflammation

Diverse mechanisms by which chemical pollutant exposure alters gut microbiota metabolism and inflammation

The human gut microbiome, the host, and the environment are inextricably linked across the life course with significant health impacts. Consisting of trillions of bacteria, fungi, viruses, and other micro-organisms, microbiota living within our gut are particularly dynamic and responsible for digestion and metabolism of diverse classes of ingested chemical pollutants. Exposure to chemical pollutants not only in early life but throughout growth and into adulthood can alter human hosts' ability to absorb and metabolize xenobiotics, nutrients, and other components critical to health and longevity. Inflammation is a common mechanism underlying multiple environmentally related chronic conditions, including cardiovascular disease, multiple cancer types, and mental health. While growing research supports complex interactions between pollutants and the gut microbiome, significant gaps exist. Few reviews provide descriptions of the complex mechanisms by which chemical pollutants interact with the host microbiome through either direct or indirect pathways to alter disease risk, with a particular focus on inflammatory pathways. This review focuses on examples of several classes of pollutants commonly ingested by humans, including (i) heavy metals, (ii) persistent organic pollutants (POPs), and (iii) nitrates. Digestive enzymes and gut microbes are the first line of absorption and metabolism of these chemicals, and gut microbes have been shown to alter compounds from a less to more toxic state influencing subsequent distribution and excretion. In addition, chemical pollutants may interact with or alter the selection of more harmful and less commensal microbiota, leading to gut dysbiosis, and changes in receptor-mediated signaling pathways that alter the integrity and function of the gut intestinal tract. Arsenic, cadmium, and lead (heavy metals), influence the microbiome directly by altering different classes of bacteria, and subsequently driving inflammation through metabolite production and different signaling pathways (LPS/TLR4 or proteoglycan/TLR2 pathways). POPs can alter gut microbial composition either directly or indirectly depending on their ability to activate key signaling pathways within the intestine (e.g., PCB-126 and AHR). Nitrates and nitrites' effect on the gut and host may depend on their ability to be transformed to secondary and tertiary metabolites by gut bacteria. Future research should continue to support foundational research both in vitro, in vivo, and longitudinal population-based research to better identify opportunities for prevention, gain additional mechanistic insights into the complex interactions between environmental pollutants and the microbiome and support additional translational science.

Carbon Dot-Stabilized Hydrogel Composite: A New Adsorbent for Efficient and Sustainable Pb(II) Removal

In this paper, a carbon dot hydrogel composite (CDs-Hy) capable of efficiently removing Pb(II) was prepared by hydrogen bonding self-assembly in combination with carbon dots and a hydrogel. CDs-Hy was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), and the effect of the adsorption conditions on the adsorption efficiency of CDs-Hy was studied. The results of the study showed that the incorporation of carbon dots, on the one hand, significantly increased the adsorption capacity of the material. On the other hand, it can increase the stability of hydrogels in aqueous solution. The possible adsorption mechanisms were further verified as ion exchange and coordination. CDs-Hy is a novel adsorbent material capable of removing Pb2+ efficiently, which can be reused several times with high stability.

Association between exposure to multiple metals and stress urinary incontinence in women: a mixture approach

There is limited evidence linking exposure to heavy metals, especially mixed metals, to stress urinary incontinence (SUI). This study aimed to explore the relationship between multiple metals exposure and SUI in women. The data were derived from the National Health and Nutrition Examination Survey (NHANES), 2007-2020. In the study, a total of 13 metals were analyzed in blood and urine. In addition, 5155 adult women were included, of whom 2123 (41.2%) suffered from SUI. The logistic regression model and restricted cubic spline (RCS) were conducted to assess the association of single metal exposure with SUI risk. The Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) were used to estimate the combined effect of multiple metals exposure on SUI. First, we observed that blood Pb, Hg and urinary Pb, Cd were positively related to SUI risk, whereas urinary W was inversely related by multivariate logistic regression (all p-FDR < 0.05). Additionally, a significant non-linear relationship between blood Hg and SUI risk was observed by RCS analysis. In the co-exposure models, WQS model showed that exposure to metal mixtures in blood [OR (95%CI) = 1.18 (1.06, 1.31)] and urine [OR (95%CI) = 1.18 (1.03, 1.34)] was positively associated with SUI risk, which was consistent with the results of BKMR model. A potential interaction was identified between Hg and Cd in urine. Hg and Cd were the main contributors to the combined effects. In summary, our study indicates that exposure to heavy metal mixtures may increase SUI risk in women.

Combined exposure to multiple metals on abdominal aortic calcification: results from the NHANES study

Exposure to metals increases the risk of many diseases and has become a public health concern. However, few studies have focused on the effect of metal on abdominal aortic calcification (AAC), especially the combined effects of metal mixtures. In this study, we aim to investigate the combined effect of metals on AAC risk and determine the key components in the multiple metals. We tried to investigate the relationship between multiple metal exposure and AAC risk. Fourteen urinary metals were analyzed with five statistical models as follows: generalized linear regression, weighted quantile sum regression (WQS), quantile g-computation (Qgcomp), and Bayesian kernel machine regression (BKMR) models. A total of 838 participants were involved, of whom 241 (28.8%) had AAC. After adjusting for covariates, in multiple metal exposure logistic regression, cadmium (Cd) (OR = 1.364, 95% CI = 1.035-1.797) was positively associated with AAC risk, while cobalt (Co) (OR = 0.631, 95% CI = 0.438-0.908) was negatively associated with AAC risk. A significant positive effect between multiple metal exposure and AAC risk was observed in WQS (OR = 2.090; 95% CI = 1.280-3.420, P < 0.01), Qgcomp (OR = 1.522, 95% CI = 1.012-2.290, P < 0.05), and BKMR models. It was found that the positive association may be driven primarily by Cd, lead (Pb), uranium (U), and tungsten (W). Subgroups analysis showed the association was more significant in participants with BMI ≥ 25 kg/m2, abdominal obesity, drinking, and smoking. Our study shows that exposure to multiple metals increases the risk of AAC in adults aged ≥ 40 years in the USA and that Cd, Pb, U, and W are the main contributors. The association is stronger in participants who are obese, smoker, or drinker.

Insights into the mechanism of transcription factors in Pb2+-induced apoptosis

The health risks associated with exposure to heavy metals, such as Pb2+, are increasingly concerning the public. Pb2+ can cause significant harm to the human body through oxidative stress, autophagy, inflammation, and DNA damage, disrupting cellular homeostasis and ultimately leading to cell death. Among these mechanisms, apoptosis is considered crucial. It has been confirmed that transcription factors play a central role as mediators during the apoptosis process. Interestingly, these transcription factors have different effects on apoptosis depending on the concentration and duration of Pb2+ exposure. In this article, we systematically summarize the significant roles of several transcription factors in Pb2+-induced apoptosis. This information provides insights into therapeutic strategies and prognostic biomarkers for diseases related to Pb2+ exposure.

Influence of lead-induced toxicity on the inflammatory cytokines

Lead (Pb2+) is a hazardous heavy metal that is pervasive in the human environment as a result of anthropogenic activity, and poses serious health risks, particularly in children. Due to its innumerable unique physical and chemical properties, it has various applications; therefore, it has become a common environmental pollutant. Lead may cause oxidative stress, and accumulating evidence indicates that oxidative stress influences the pathophysiology of lead poisoning, also called plumbism. The immune system is continually exposed to various environmental pathogens and xenobiotics, including heavy metals such as lead, and appears to be one of the most vulnerable targets. After being exposed to lead, cells are subjected to oxidative stress as a result of reactive oxygen species (ROS) production. When the generation and consumption of ROS are out of equilibrium, various cell structures, particularly phospholipids are disrupted leading to lipid peroxidation. Various inflammatory signalling pathways are activated as a consequence, along with reduced disease resistance, inflammation, autoimmunity, sensitization and disruption of the cell-mediated and humoral immune systems. Lead negatively affects the metabolism of cytokines, including the interleukins IL-2, IL-1b, IL-6, IL-4, IL-8, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN), as well as the expression and functioning of inflammatory enzymes such as cyclooxygenases. However, the cause of toxicity depends on the kind of lead, dosage, route of entry, exposure period, age, host and genetic predisposition.

Blood Pb levels are associated with prostate cancer prevalence among general adult males: Linking National Cancer Registry (2002-2017) and KNHANES (2008-2017) databases of Korea

BACKGROUND

Exposure to heavy metals may increase the risk of developing prostate cancer. However, these observations are often inconsistent and not based on clinically diagnosed cases.

OBJECTIVE

To investigate the association of lead (Pb), cadmium (Cd), and mercury (Hg) exposure with clinically determined prostate cancer cases among adult males in South Korea.

METHODS

Metal biomonitoring data and cancer information from the general Korean population were extracted by linking National Cancer Center (NCC) cancer registration data (2002-2017) with Korea National Health and Nutrition Examination Survey (KNHANES) data (2008-2017). Among them, 46 prostate cancer cases (designated as 'all-prostate'), including 25 diagnosed after heavy metal measurement (designated as 'post-prostate'), and 93 matching controls were chosen. Logistic regression analysis was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) between the heavy metal levels and prostate cancer.

RESULTS

Post-prostate patients exhibited higher blood Pb levels than controls (median 3.1 μg/dL vs. 2.38 μg/dL, p = 0.01). For all-prostate cancer, the OR of prostate cancer increased by 2.04-fold for every doubling of Pb levels (95% CI = 1.08-3.87, p = 0.03). The OR was also significantly elevated when comparing the third quartile (Q3) to the lowest quartile (Q1), with ORs ranging from 3.38 to 7.95, depending on model (p < 0.05). Blood Pb levels maintained a positive association with inconsistent significance for post-prostate cancer patients. For Cd and Hg, no statistically significant association was established.

SIGNIFICANCE

By linking two national health databases for the first time, we constructed an unbiased database of prostate cancer cases and matching controls. We found that blood Pb concentrations were associated with the risk of prostate cancer in Korean men at the current level of exposure.

Could the gut microbiota be capable of making individuals more or less susceptible to environmental toxicants?

Environmental toxicants are chemical substances capable to impair environmental quality and exert adverse effects on humans and other animals. The main routes of exposure to these pollutants are through the respiratory tract, skin, and oral ingestion. When ingested orally, they will encounter trillions of microorganisms that live in a community - the gut microbiota (GM). While pollutants can disrupt the GM balance, GM plays an essential role in the metabolism and bioavailability of these chemical compounds. Under physiological conditions, strategies used by the GM for metabolism and/or excretion of xenobiotics include reductive and hydrolytic transformations, lyase and functional group transfer reactions, and enzyme-mediated functional transformations. Simultaneously, the host performs metabolic processes based mainly on conjugation, oxidation, and hydrolysis reactions. Thus, due to the broad variety of bacterial enzymes present in GM, the repertoire of microbial transformations of chemicals is considered a key component of the machinery involved in the metabolism of pollutants in humans and other mammals. Among pollutants, metals deserve special attention once contamination by metals is a worldwide problem, and their adverse effects can be observed even at very low concentrations due to their toxic properties. In this review, bidirectional interaction between lead, arsenic, cadmium, and mercury and the host organism and its GM will be discussed given the most recent literature, presenting an analysis of the ability of GM to alter the host organism's susceptibility to the toxic effects of heavy metals, as well as evaluating the extent to which interventions targeting the microbiota could be potential initiatives to mitigate the adverse effects resulting from poisoning by heavy metals. This study is the first to highlight the overlap between some of the bacteria found to be altered by metal exposure and the bacteria that also aid the host organism in the metabolism of these metals. This could be a key factor to determine the beneficial species able to minimize the toxicity of metals in future therapeutic approaches.

Maternal prenatal lead levels and neonatal brain volumes: Testing moderations by maternal depressive symptoms and family income

There is considerable evidence that prenatal lead exposure is detrimental to child cognitive and socio-emotional development. Further evidence suggests that the effects of prenatal lead on developmental outcomes may be conditional upon exposure to social stressors, such as maternal depression and low socioeconomic status. However, no studies have examined associations between these co-occurring stressors during pregnancy and neonatal brain volumes. Leveraging a sample of 101 mother-infant dyads followed beginning in mid-pregnancy, we examined the main effects of prenatal urinary lead levels on neonatal lateralized brain volumes (left and right hippocampus, amygdala, cerebellum, frontal lobes) and total gray matter. We additionally tested for moderations between lead and depressive symptoms and between lead and family income relative to the federal poverty level (FPL) on the same neurodevelopmental outcomes. Analyses of main effects indicated that prenatal lead was significantly (ps < 0.05) associated with reduced right and left amygdala volumes (βs = -0.23- -0.20). The testing and probing of cross-product interaction terms using simple slopes indicated that the negative effect of lead on the left amygdala was conditional upon mothers having low depressive symptoms or high income relative to the FPL. We interpret the results in the context of trajectories of prenatal and postnatal brain development and susceptibility to low levels of prenatal lead in the context of other social stressors.

Peiminine alleviate coliti-like phenotype in mice induced by lead exposure

The deleterious impact of lead (Pb) pollution on human health is evident in both domestic and occupational settings, provoking an inflammatory response across multiple tissue, limited attention has been devoted to its adverse effects on colitis and the underlying mechanisms. Peiminine (PMI) has been recognized for its anti-inflammatory properties, yet its specific anti-inflammatory effects in lead-induced colitis models remain elusive. Through the establishment of both in vivo and in vitro lead exposure models, suggests that lead exposure can induce colitis and that PMI regulates lead exposure-induced colitis by inhibiting the NF-kB signaling pathway, and alleviates the ability of lead to apoptosis and inflammation levels in intestinal epithelial cells. Consequently, these results present a promising avenue for further exploration of the molecular mechanisms underlying lead-induced colitis, evaluation of the associated risks linked to lead exposure, and the development of therapeutic interventions for colitis resulting from lead exposure.

Proteome signatures of joint toxicity to arsenic (As) and lead (Pb) in human brain organoids with optic vesicles

Arsenic (As) and lead (Pb) are toxins found in the natural surroundings, and the harmful health outcomes caused by the co-exposure of such toxins have become a considerable problem. However, the joint neurotoxicity of As and Pb to neurodevelopment and the underlying mechanisms remain unclear. Pluripotent stem cell-derived human brain organoids are emerging animal model alternatives for understanding neurological-related diseases. Therefore, we utilized brain organoids with optic vesicles (OVB-organoids) to systematically analyze the neurotoxicity of As and Pb. After 24 h of As and/or Pb exposure, hematoxylin-eosin staining revealed that As and Pb exposure could cause disorders in the structure of the ventricular zone and general cell disarrangement in OVB-organoids. Immunostaining displayed that OVB-organoids are more susceptible to As and Pb co-exposure than independent exposure in apoptosis, proliferation, and cell differentiation. Meanwhile, even though As and Pb could both hinder cell proliferation, contrary to Pb, As could induce an increasing proportion of mitotic (G2/M) cells. The proteome landscape of OVB-organoids illustrated that Pb synergized with As in G2/M arrest and the common role of As and Pb in carcinogenesis. Besides, proteomics analyses suggested the consequential role of autophagy and Wnt pathway in the neurotoxicity of As and Pb co-exposure. Overall, our findings provide penetrating insights into the cell cycle, carcinogenesis, autophagy, and Wnt pathway underlying the As and Pb binary exposure scenarios, which could enhance our understanding of the mixture neurotoxicity mechanisms.

Investigating the Effectiveness of Exopolysaccharide-Producing Lactic Acid Bacteria in Biosorbing Lead (II), Attaching to Caco-2 Cells, and Provoking Antiinflammatory Responses

Lead is a common toxic heavy metal with harmful effects on the human body and is widely used in several industries. It can contaminate the environment by air and water emissions and can enter the human body through the respiratory tract, ingestion, or skin contact. Lead is considered as a persistent environmental pollutant, with a half-life of 30 days in the blood, and exists in the skeletal system for decades and causes damage to other systems. Biosorption is receiving increasing attention. Due to its high efficiency and economic value in removing heavy metals from the environment, a variety of biosorption methods can be used for the removal of heavy metals. Lactic acid bacteria (LAB) strains were capable of attaching to both human skin stratum corneum HaCaT cells and human rectal cancer Caco-2 cells. NBM-04-10-001 and NBM-01-07-003 significantly reduced the secretion of IL-6 and IL-8 after coculture with HaCaT cells. In the immune response of RAW264.7 mouse macrophages, high bacterial counts reduced the concentrations of IL-6 and TNF-α in a dose-dependent manner. The results of animal experiments revealed that feeding lead solution exerted no effect on the animal's food intake, and feeding PURE LAC NBM11 powder could effectively remove lead content in the blood. The group fed with PURE LAC NBM11 powder showed significantly less damage and lesions to liver cells. The LAB powder developed in this study has the potential to bind metals, preventing them from entering the body and protecting the host. LAB can be an ideal strain for future bioadsorption chelators.

The Association Between Blood Lead Levels and Coronary Artery Calcium Score Determined by Using Coronary Computed Tomography Angiography

BACKGROUND

Lead exposure is a known risk factor for cardiovascular disease (CVD), and coronary artery calcification (CAC) is a biomarker for diagnosing atherosclerotic CVD. This study investigated the association between blood lead level (BLL) and CAC using coronary computed tomography (CT) angiography.

METHODS

This study enrolled 2,189 participants from the general population with no history or symptoms of CVD. All participants underwent coronary CT angiography, health examination, and BLL testing. The association between coronary artery calcium score (CACS) and BLL was analyzed.

RESULTS

The arithmetic mean of BLL was 2.71 ± 1.26 μg/dL, and the geometric mean was 2.42 (1.64) μg/dL, ranging from 0.12 to 10.14 μg/dL. There was a statistically significant positive correlation between CACS and BLL (r = 0.073, P < 0.001). Mean BLLs among predefined CACS categories were as follows: absent grade (CACS = 0), 2.67 ± 1.23 μg/dL; minimal grade (> 0, < 10), 2.81 ± 1.25 μg/dL; mild grade (≥ 10, < 100), 2.74 ± 1.29 μg/dL; moderate grade (≥ 100, < 400), 2.88 ± 1.38 μg/dL; severe grade (≥ 400): 3.22 ± 1.68 μg/dL. The odds ratio for severe CAC was 1.242 in association with an 1 μg/dL increase in BLL (P = 0.042).

CONCLUSION

Using coronary CT angiography, we determined a positive correlation between BLL and CAC among participants without CVD from the general population. To reduce the burden of CVD, efforts and policies should be geared toward minimizing environmental lead exposure.

Microglia and Astroglia-The Potential Role in Neuroinflammation Induced by Pre- and Neonatal Exposure to Lead (Pb)

Neuroinflammation is one of the postulated mechanisms for Pb neurotoxicity. However, the exact molecular mechanisms responsible for its pro-inflammatory effect are not fully elucidated. In this study, we examined the role of glial cells in neuroinflammation induced by Pb exposure. We investigated how microglia, a type of glial cell, responded to the changes caused by perinatal exposure to Pb by measuring the expression of Iba1 at the mRNA and protein levels. To assess the state of microglia, we analyzed the mRNA levels of specific markers associated with the cytotoxic M1 phenotype (Il1b, Il6, and Tnfa) and the cytoprotective M2 phenotype (Arg1, Chi3l1, Mrc1, Fcgr1a, Sphk1, and Tgfb1). Additionally, we measured the concentration of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). To assess the reactivity and functionality status of astrocytes, we analyzed the GFAP (mRNA expression and protein concentration) as well as glutamine synthase (GS) protein level and activity. Using an electron microscope, we assessed ultrastructural abnormalities in the examined brain structures (forebrain cortex, cerebellum, and hippocampus). In addition, we measured the mRNA levels of Cxcl1 and Cxcl2, and their receptor, Cxcr2. Our data showed that perinatal exposure to Pb at low doses affected both microglia and astrocyte cells' status (their mobilization, activation, function, and changes in gene expression profile) in a brain-structure-specific manner. The results suggest that both microglia and astrocytes represent a potential target for Pb neurotoxicity, thus being key mediators of neuroinflammation and further neuropathology evoked by Pb poisoning during perinatal brain development.

Hepatoprotective effect of avicularin on lead-induced steatosis, oxidative stress, and inflammation in mice associated with the MAPK/HSP60/NLRP3 and SREBP1c pathway

Lead (Pb), an environmental hazard, causes severe diseases in the liver, kidney, cardiovascular system, hematopoietic system, reproductive system, and nervous system. Avicularin (AVI), the main dietary flavonoid found in many citrus fruits, exhibited potential protective properties on organs. However, the molecular mechanisms of these protective actions are currently not clear. In our study, the effects of AVI on Pb-induced hepatotoxicity were evaluated using ICR mice. Changes in oxidative stress, inflammation, lipid metabolism, and related signaling were evaluated. We found for the first time that treatment with AVI significantly reduced hepatic steatosis, inflammation, and oxidative stress induced by Pb. AVI attenuated Pb-induced liver dysfunction and lipid metabolism disorder in mice. AVI decreased the serum biochemical indicators of lipid metabolism. AVI decreased the expression levels of lipid metabolism-related protein SREBP-1c, acetyl-CoA carboxylase (ACC), and FAS. AVI suppressed Pb-induced inflammation in livers, as indicated by decreasing the TNF-α and IL-1β levels. AVI suppressed oxidative stress by increasing the activation of SOD, CAT, and GPx. Furthermore, AVI inhibited the activities of JNK, ERK, p38, and NF-κB. AVI further decreased the levels of HSP60, NLRP3, p-IκBα, and p-p65 in the livers of mice. Collectively, this study indicated that AVI mitigated Pb-induced hepatic steatosis, oxidative stress, and inflammation by regulating the SREBP-1c and MAPK/HSP60/NLRP3 signaling pathways.

Bifunctional collagen fiber/carbon quantum dot fluorescent adsorbent for efficient adsorption and detection of Pb2

In this work, fluorescent adsorbents that can efficiently detect and remove Pb²⁺ were developed by integrating the designed amino-modified carbon quantum dots and carboxyl-modified collagen. The adsorption properties of the fluorescent adsorbent were further optimized and analyzed using a series of response surface experiments. The maximum adsorption concentration for Pb²⁺ was 183 mg.g^-1. The adsorption isotherms fit well with the Langmuir model, and the adsorption kinetics fit with the pseudo-second-order model. The emission intensity of the fluorescent adsorbent gradually decreased with the increase of the concentration of Pb²⁺, and had a good linear correlation. In addition, the mechanism of detection and removal of Pb²⁺ by fluorescent adsorbents was further demonstrated. The novel three-dimensional structured fluorescent aerogel can be used as a promising adsorbent with good adsorption concentration and sensing ability for Pb²⁺, which shows great prospects in wastewater.

Cadmium, Lead, Chronic Physiological Stress and Endometrial Cancer: How Environmental Policy Can Alter the Exposure of At-Risk Women in the United States

The health and life outcomes of individuals are intertwined with the context in which they grow and live. The totality of exposures one experiences affects health in the short term and throughout the life course. Environmental exposure to multiple contaminants can increase stress levels in individuals and neighborhoods with psychosocial stressors such as crime, drug and alcohol misuse, and violence also taking a toll on individual and neighborhood wellbeing. In addition, the availability, organization, and quality of local institutions and infrastructure all affect health in the short and long term. The role of these factors in endometrial cancer will be explored in this paper. In addition, policy implications regarding lead, chronic physiological stress, and endometrial cancer will be explored to ascertain the impact of these factors on at-risk women.

In silico identification of molecular mechanisms for stroke risk caused by heavy metals and their mixtures: sponges and drugs involved

This study used various approaches and databases to evaluate the molecular processes and identify miRNA sponges and drugs associated with the development of stroke caused by heavy metals and their combinations. We found that the genes ALB (albumin), IL1B (Interleukin-1β), F2 (coagulation factor II), APOA1 (apolipoprotein A1), IL6 (Interleukin 6), and NOS2 (nitric oxide synthase 2) were linked to the development of strokes by 18 chemicals and a combination of cadmium, copper, and lead. These results may point to the significance of detoxification and neuroinflammation in stroke as well as the potential for targeting these genes in future stroke therapies. ALB and IL1B were the most common and significant genes. The "selenium micronutrient network," "vitamin B12 metabolism," and "folate metabolism" were shown to be the most significant pathways connected to the risk of stroke brought on by combined heavy metals. The two main cellular elements that may increase the risk of stroke caused by heavy metals were discovered to be "blood microparticle" and "endoplasmic reticulum lumen." We also observed an important chromosome (chr7p15.3), two transcription factors (NFKB2 [nuclear factor kappa B subunit 2] and NR1I2 [nuclear receptor subfamily 1 group, member 2]), and four microRNAs (hsa-miR-26a-5p, hsa-miR-9-5p, hsa-miR-124-3p, and hsa-miR-155-5p) associated with stroke caused by combined heavy metals. Additionally, for these miRNAs, we created and examined in silico microRNA sponge sequences. Triflusal and andrographolide have been identified as potential treatments for heavy metal-induced stroke. Taken together, heavy metals may be a significant contributor to the pathophysiology of stroke, but further investigation into the precise molecular pathways implicated in stroke pathophysiology is required to corroborate these findings.

Adaptive changes in redox response and decreased platelet aggregation in lead-exposed workers

Chronic lead exposure can generate pro-oxidative and pro-inflammatory conditions in the blood, related to high platelet activation and aggregation, altering cell functions. We studied ADP-stimulated aggregation and the oxidant/antioxidant system of platelets from chronically lead-exposed workers and non-exposed workers. Platelet aggregation was low in lead-exposed workers (62 vs. 97%), who had normal platelet counts and showed no clinical manifestations of hemostatic failure. ADP-activated platelets from lead-exposed workers failed to increase superoxide release (3.3 vs. 6.6 µmol/g protein), had low NADPH concentration (60 vs. 92 nmol/mg protein), high concentration of hydrogen peroxide (224 vs. 129 nmol/mg protein) and high plasma PGE₂ concentration (287 vs. 79 pg/mL). Altogether, those conditions, on the one hand, could account for the low platelet aggregation and, on the other, indicate an adaptive mechanism for the oxidative status of platelets and anti-aggregating molecules to prevent thrombotic problems in the pro-oxidant and pro-inflammatory environment of chronic lead exposure.

Association between Chronic Environmental Lead (Pb) Exposure and Cytokines in Males and Females of Reproductive Age from Kabwe, Zambia

Lead (Pb) poisoning remains a great public health challenge globally known to induce a wide range of ailments in both children and adults. The current study investigated the association of chronic environmental Pb exposure and immunomodulatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) in adult males and females living in Kabwe, Zambia. The standard human cytokine/chemokine Milliplex assay was used to quantify plasma cytokines from four groups categorized as low (<10 μg/dL) and high (>10 μg/dL) blood lead level (BLL) groups, namely, low BLL female (n = 47; BLL = 3.76 μg/dL), low BLL Male (n = 43; BLL = 4.13 μg/dL), high BLL female (n = 21; BLL = 23.5 μg/dL), and high BLL male (n = 18; BLL = 23.7 μg/dL), respectively. The low BLL group was associated with increased TNF-α levels, and the high BLL group was associated with reduced TNF-α levels in female subjects. No associations between BLL and the levels of IL-8 and TNF-α cytokines were observed in either females or males, respectively. A negative correlation between BLL and TNF-α was found in female subjects, suggesting that an increase in BLL accompanied by a reduction in TNF-α. The reduced levels of circulating TNF-α in female subjects suggest that chronic Pb exposure could predispose females to immune and inflammation-related disorders than their male counterparts. Further studies are recommended to ascertain the impact of chronic Pb exposure on immunomodulatory cytokines, especially in females.

High-fat diet in mice led to increased severity of spermatogenesis impairment by lead exposure: perspective from gut microbiota and the efficacy of probiotics

BACKGROUND

The mechanism of multifactorial spermatogenesis impairment is unclear. This study aimed to investigate the reproductive toxicity of lead (Pb) in mice fed a high-fat diet (HFD) and to delineate the important role of gut microbiota.

RESULTS

Results showed that, compared with mice fed a normal diet (ND), Pb exposure caused more severe spermatogenesis impairment in HFD-fed mice, including decreased sperm count and motility, seminiferous tubule injury, serum and intratesticular testosterone decline, and downregulated expression level of spermatogenesis-related genes. Besides, 16S sequencing indicated that HFD-fed mice had increased severity of gut microbiota dysbiosis by Pb exposure compared to ND-fed mice. With fecal microbiota transplantation, the same trend of spermatogenesis impairment occurred in recipient mice, which confirmed the important role of gut microbiota. Moreover, probiotics supplementation restored the gut microbial ecosystem, and thus improved spermatogenic function.

CONCLUSION

Our work suggested that a population with HFD might face more reproductive health risks upon Pb exposure, and revealed an intimate linkage between microbiota dysbiosis and spermatogenesis impairment, accompanied by the potential usefulness of probiotics as prophylactic and therapeutic. © 2022 Society of Chemical Industry.

Comparative analysis of Acomys cahirinus and Mus musculus responses to genotoxicity, oxidative stress, and inflammation

The Egyptian spiny mouse, Acomys cahirinus, is a recently described model organism for regeneration studies. It has surprising powers of regeneration with relatively fast repairing mechanisms and reduced inflammation form compared to other mammals. Although several studies have documented the exceptional capabilities of Acomys to regenerate different tissues after injury, its response to different cellular and genetic stresses is not yet investigated. Therefore, the current study aimed to investigate Acomys abilities to resist genotoxicity, oxidative stress and inflammation induced by acute and subacute treatments with lead acetate. Responses of Acomys were compared with those of the lab mouse (Mus musculus), which displays signatures of the "typical" mammalian response to various stressors. Cellular and genetic stresses were induced by using acute and subacute doses of Lead acetate (400 mg/kg and 50 mg/kg for 5 days, respectively). The assessment of genotoxicity was carried out by using comet assay, while oxidative stress was evaluated by measuring the biomarkers; MDA, GSH and antioxidant enzymes CAT and SOD. Moreover, inflammation was assessed by analyzing the expression of some inflammatory-regeneration-related genes: CXCL1, IL1-β, and Notch 2 and immunohistochemical staining of TNF-α protein in brain tissue, in addition to histopathological examination of brain, liver, and kidneys. The obtained results revealed a unique resistance potency of Acomys to genotoxicity, oxidative stress, and inflammation in certain tissues in comparison to Mus. Altogether, the results revealed an adaptive and protective response to cellular and genetic stresses in Acomys.

The combined effect of heavy metals and polycyclic aromatic hydrocarbons on arthritis, especially osteoarthritis, in the U.S. adult population

The evaluation of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) impact on arthritis is usually limited to the analysis of the arthritis subtype (rheumatoid arthritis, RA), whereas studies on osteoarthritis (OA) are relatively sparse. Furthermore, the combined effect of HMs and PAHs co-exposure on arthritis also has rarely been analyzed. Herein, we aimed to comprehensively estimate the association between HMs and PAHs (three blood HMs and six urinary PAHs metabolites) co-exposure and arthritis. Using data from the National Health and Nutrition Examination Survey (NHANES), 2003-2016, we included 9735 adults, of whom 2464 had total arthritis, 1371 had OA, and 468 had RA. The logistic regression model was conducted to estimate the single effect of HMs and PAHs on arthritis. Moreover, weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR) were separately performed to assess the combined effect of HMs and PAHs co-exposure on arthritis. In the single-exposure analyses, cadmium (Cd) and lead (Pb) statistically grew the risk of total arthritis, OA, and RA. Among PAHs, 1-hydroxynaphthalene (1-NAP) and 3-hydroxyfluorene (3-FLU) showed a positive association with total arthritis, OA, and RA. Meanwhile, 2-NAP also was significantly associated with total arthritis. 2-NAP, 2-FLU, and 1-hydroxyphenanthrene (1-PHE) also were significantly associated with RA. Furthermore, the three complementary models consistently demonstrated that co-exposure to high levels of HMs and PAHs was positively associated with total arthritis, OA, and RA risk. The above associations were more obvious in young and medium-aged people. Interestingly, BKMR analyses indicated that 1-NAP might interact with Cd and 3-FLU in total arthritis, while Pb might interact with Cd in OA. Therefore, this study provided novel evidence that co-exposure to HMs and PAHs positively correlated with arthritis, especially OA, and these results were worthy of further prospective studies.

Pb(II) coordination to the nonclassical zinc finger tristetraprolin: retained function with an altered fold

Tristetraprolin (TTP) is a nonclassical CCCH zinc finger (ZF) that plays a crucial role in regulating inflammation. TTP regulates cytokine mRNAs by specific binding of its two conserved ZF domains (CysX₈CysX₅CysX₃His) to adenylate-uridylate-rich sequences (AREs) at the 3'-untranslated region, leading to degradation of the RNA. Dysregulation of TTP in animal models has demonstrated several cytokine-related syndromes, including chronic inflammation and autoimmune disorders. Exposure to Pb(II), a prevalent environmental toxin, is known to contribute to similar pathologies, in part by disruption of and/or competition with cysteine-rich metalloproteins. TTP's role during stress as a ubiquitous translational regulator of cell signaling (and dysfunction), which may underpin various phenotypes of Pb(II) toxicity, highlights the importance of understanding the interaction between TTP and Pb(II). The impact of Pb(II) binding on TTP's fold and RNA-binding function was analyzed via UV-Vis spectroscopy, circular dichroism, X-ray absorption spectroscopy, nuclear magnetic resonance spectroscopy, and fluorescence anisotropy. A construct containing the two ZF domains of TTP (TTP-2D) bound to Pb(II) with nanomolar affinity and exhibited a different geometry and fold in comparison to Zn₂-TTP-2D. Despite the altered secondary structure, Pb(II)-substituted TTP-2D bound a canonical ARE sequence more selectively than Zn₂-TTP-2D. Taken together, these data suggest that Pb(II) may interfere with proper TTP regulation and hinder the cell's ability to respond to inflammation.

Epigenome-wide DNA methylation in leukocytes and toenail metals: The normative aging study

BACKGROUND

Environmental metal exposures have been associated with multiple deleterious health endpoints. DNA methylation (DNAm) may provide insight into the mechanisms underlying these relationships. Toenail metals are non-invasive biomarkers, reflecting a medium-term time exposure window.

OBJECTIVES

This study examined variation in leukocyte DNAm and toenail arsenic (As), cadmium (Cd), lead (Pb), manganese (Mn), and mercury (Hg) among elderly men in the Normative Aging Study, a longitudinal cohort.

METHODS

We repeatedly collected samples of blood and toenail clippings. We measured DNAm in leukocytes with the Illumina HumanMethylation450 K BeadChip. We first performed median regression to evaluate the effects of each individual toenail metal on DNAm at three levels: individual cytosine-phosphate-guanine (CpG) sites, regions, and pathways. Then, we applied a Bayesian kernel machine regression (BKMR) to assess the joint and individual effects of metal mixtures on DNAm. Significant CpGs were identified using a multiple testing correction based on the independent degrees of freedom approach for correlated outcomes. The approach considers the effective degrees of freedom in the DNAm data using the principal components that explain >95% variation of the data.

RESULTS

We included 564 subjects (754 visits) between 1999 and 2013. The numbers of significantly differentially methylated CpG sites, regions, and pathways varied by metals. For example, we found six significant pathways for As, three for Cd, and one for Mn. The As-associated pathways were associated with cancer (e.g., skin cancer) and cardiovascular disease, whereas the Cd-associated pathways were related to lung cancer. Metal mixtures were also associated with 47 significant CpG sites, as well as pathways, mainly related to cancer and cardiovascular disease.

CONCLUSIONS

This study provides an approach to understanding the potential epigenetic mechanisms underlying observed relations between toenail metals and adverse health endpoints.

High-density lipoprotein cholesterol modifies the association between blood lead and uric acid: results from NHANES 2005-2016

BACKGROUND

The association between blood lead (PbB) and uric acid (SUA) remains unclear in US adults without a high level of lead exposure. Additionally, the effects of high-density lipoprotein cholesterol (HDL-C) modifying this association are still unclear. Therefore, this study aims to assess the effect of modification of high-density lipoprotein cholesterol on the association between PbB and SUA.

METHOD

This research analyzed National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2016. Through several screenings, 18,578 participants over the age of 20 were eligible for the analysis. Multivariable linear regression was used to evaluate the association between PbB and SUA. By having stratified participants based on the HDL-C intake category (low HDL-C intake < 50 mg/dl; high HDL-C intake ≥ 50 mg/dl), effect modification by HDL-C was assessed through a likelihood ratio test between PbB and SUA.

RESULT

Multivariable linear regression indicated that PbB positively affects SUA (β = 0.19, 95% CI 0.16-0.22). The relationship between PbB and SUA was different in the low and high HDL-C intake group (β 0.12 95% Cl 0.08-0.16 vs. β 0.26 95% Cl 0.22 ~ - 0.30). Furthermore, high-density lipoprotein cholesterol significantly modified the relationship between PbB and SUA in all models which indicates that the interaction of lead exposure and HDL-C is more dangerous than the sum of the individual effects.

CONCLUSIONS

Our study shows that high-density lipoprotein cholesterol and blood lead have an interactive effect on increasing uric acid, which may have great importance for clinical medication.

Assessment of Some Heavy Metals and Their Relationship with Oxidative Stress and Immunological Parameters in Aquatic Animal Species

Heavy metal accumulation changes the immune system and leads to oxidative damage in aquatic animals. The present study evaluated the correlation between heavy metal accumulation, with immunological and oxidative stress parameters, in various species in the aquatic environment of Western Iran. Fresh samples included fish (trout and carp) and shrimp obtained from Sanandaj aquaculture. After blood sampling and serum isolation for immunological study, meat sections of these animals were used to measure heavy metal concentrations to determine the oxidative stress and immunological parameters. The highest concentrations of Pb (0.82 ± 0.10), As (0.53 ± 0.18), Hg (0.47 ± 0.08), and Zn (28.77 ± 1.88) (µg/g) were found in trout, while the lowest accumulation of heavy metals except for Cd (0.24 ± 0.11) and Se (1.57 ± 0.42) (µg/g) were observed in shrimp. The antioxidant enzymes glutathione peroxidase (GPx) (1.89 ± 0.13) and superoxide dismutase (SOD) (1.96 ± 0.62) U/mg showed the highest concentrations in shrimp and lowest in the trout. Significant negative correlations were found between these enzymes with As and Pb in trout and carp. A significant positive correlation was determined between Se and Zn with GPx and a negative correlation with malondialdehyde (MDA) in shrimp. Immunological biomarkers indicated the concentrations of IL-6, TNF-α, and IFN-Ƴ were higher in fish than in shrimp, and the lowest IgM level was obtained in Shrimp. Increased Pb and Cd showed a significant relationship with increased IL-6 and TNF-α in trout compared to shrimp and carp. An increase in As and Se concentration beyound maximum permissible limits (MPL) were recorded in fish and shrimp, while a Zn level less than MPL was recorded. The target hazard quotients (THQ) and target cancer risk (TR) values of non-essential heavy metals were obtained under acceptable ranges. We suggest reducing the As and Pb content under aquaculture farms and increase in the amount of Zn through diets to keep healthy immunological and physiological conditions for aquatic species in the west of Iran.

Heavy Metal(loid) Body Burden in Environmentally Exposed Children With and Without Internalizing Behavior Problems

The prevalence of internalizing behavior disorders in children is increasing. Reasons for increasing anxiety and depression include several factors with a less studied consideration being the potential neurotoxic effects of environmental exposures. One group at risk for environmental exposures is children living near coal-burning power plants with coal ash storage facilities. Multivariate logistic regression was used to assess the relationship between metal(loid) exposures and internalizing behaviors in children aged 6-14 years. Metal(loid)s in nail samples were determined by Proton-Induced X-ray Emission and internalizing behavior problems were obtained from the parent ratings on the Child Behavior Checklist. Results indicated that concentrations of metal(loid)s in nails differ between children with internalizing behaviors and without internalizing behaviors. Logistic regression models suggested that exposure to zinc and imputed zirconium were associated with internalizing behaviors in children. However, when a sex-metal(loid) interaction term was included, none of the metal(loid)s were associated with internalizing behaviors indicating a role of sex differences in neurotoxicity with zinc and copper showing effects only for males. In all models, greater exposure to traffic was associated with internalizing behaviors. Zinc has previously been shown to increase risk for mental health problems, while zirconium has received less attention. Out findings indicate that environmental exposures of zinc and zirconium deserve further attention in studies of childhood internalizing disorders.

Dietary fiber ameliorates lead-induced gut microbiota disturbance and alleviates neuroinflammation

Dietary fiber (DF) is a carbohydrate from the edible part of plants and has the functions of promoting gastrointestinal motility, regulating gut microbiota (GM) and improving health. Lead is a non-essential toxic heavy metal that can accumulate in the environment over time and enter the body through the respiratory tract, skin and gastrointestinal tract. Lead not only causes disturbances in GM but also leads to loss of homeostasis of immune functions, causes neuronal damage and results in neuroinflammation. The scientific literature has reported that DF had anti-inflammatory activity as a natural product. This review highlights the role of DF and its metabolic products in alleviating lead-induced neuroinflammation by inducing changes in the species and quantity of GM and regulating the immune system, providing a potential dietary protective strategy for lead-induced disease. © 2022 Society of Chemical Industry.

Immune Responses to COVID-19 Vaccines in Patients with Chronic Kidney Disease and Lead Exposure

Literature data regarding the response rate to COVID-19 vaccination in chronic kidney disease (CKD) patients remain inconclusive. Furthermore, studies have reported a relationship between lead exposure and susceptibility to viral infections. This study examined immune responses to COVID-19 vaccines in patients with CKD and lead exposure. Between October and December 2021, 50 lead-exposed CKD patients received two doses of vaccination against COVID-19 at Chang Gung Memorial Hospital. Patients were stratified into two groups based on the median blood lead level (BLL): upper (≥1.30 μg/dL, n = 24) and lower (<1.30 μg/dL, n = 26) 50th percentile. The patients were aged 65.9 ± 11.8 years. CKD stages 1, 2, 3, 4 and 5 accounted for 26.0%, 20.0%, 22.0%, 8.0% and 24.0% of the patients, respectively. Patients in the lower 50th percentile of BLL had a lower proportion of CKD stage 5 than patients in the upper 50th percentile BLL group (p = 0.047). The patients in the lower 50th percentile BLL group also received a higher proportion of messenger RNA vaccines and a lower proportion of adenovirus-vectored vaccines than the patients in the upper 50th percentile BLL group (p = 0.031). Notably, the neutralizing antibody titers were higher in the lower 50th percentile than in the upper 50th percentile BLL group. Furthermore, the circulating levels of granulocyte-colony stimulating factor, interleukin-8, monocyte chemoattractant protein-1 and macrophage inflammatory protein-1α were higher in the upper 50th percentile than in the lower 50th percentile BLL group. Therefore, it was concluded that lead-exposed CKD patients are characterized by an impaired immune response to COVID-19 vaccination with diminished neutralizing antibodies and augmented inflammatory reactions.

Chronic Community Exposure to Environmental Metal Mixtures Is Associated with Selected Cytokines in the Navajo Birth Cohort Study (NBCS)

Many tribal populations are characterized by health disparities, including higher rates of infection, metabolic syndrome, and cancer-all of which are mediated by the immune system. Members of the Navajo Nation have suffered chronic low-level exposure to metal mixtures from uranium mine wastes for decades. We suspect that such metal and metalloid exposures lead to adverse health effects via their modulation of immune system function. We examined the relationships between nine key metal and metalloid exposures (in blood and urine) with 11 circulating biomarkers (cytokines and CRP in serum) in 231 pregnant Navajo women participating in the Navajo Birth Cohort Study. Biomonitored levels of uranium and arsenic species were considerably higher in participants than NHANES averages. Each biomarker was associated with a unique set of exposures, and arsenic species were generally immunosuppressive (decreased cellular and humoral stimulating cytokines). Overall, our results suggest that environmental metal and metalloid exposures modulate immune status in pregnant Navajo women, which may impact long-term health outcomes in mothers and their children.

Circulating metals, leukocyte microRNAs and microRNA networks: A profiling and functional analysis in Chinese adults

BACKGROUND

Metals in the human body represent both environmental exposure and nutritional status. Little is known about the miRNA signature in relation to circulating metals in humans.

OBJECTIVES

To characterize metal-associated miRNAs in leukocytes, individually and collectively as networks.

METHODS

In a panel of 160 Chinese adults, we measured 23 metals/metalloids in plasma, and sequenced miRNAs and mRNAs in leukocytes. We used linear regression to model the associations between ln-transformed metal concentrations and normalized miRNA levels adjusting for potential confounders. We inferred the enriched leukocyte subtypes for the identified miRNAs using an association approach. We utilized mRNA sequencing data to explore miRNA functions. We also constructed modules to identify metal-associated miRNA networks.

RESULTS

We identified 55 metal-associated miRNAs at false discovery rate-adjusted P < 0.05. In particular, we found that lead, nickel, and vanadium were positively associated with potentially lymphocyte-enriched miR-142-3p, miR-150-3p, miR-28-5p, miR-361-3p, and miR-769-5p, and were inversely associated with potentially granulocyte-enriched let-7a/c/d-5p and miR-1294. Interestingly, the five lymphocyte-enriched miRNAs inhibited, whereas miR-1294 activated, ROS and DNA repair pathways. We further confirmed the findings using oxidative damage biomarkers. Next, we clustered co-expressed miRNAs into modules, and identified four miRNA modules that were associated with different metals. The identified modules represented miRNAs enriched in different leukocyte subtypes, and were involved in biological processes including hematopoiesis and immune response, mitochondrial functions, and response to the stimulus.

CONCLUSIONS

At commonly exposed low levels, circulating metals were associated with distinct miRNA signatures in leukocytes. The identified miRNAs, individually or as regulatory networks, may provide a mechanistic link between metal exposure and pathophysiological changes in the immune system.

Alhagi maurorum Ethanolic Extract Rescues Hepato-Neurotoxicity and Neurobehavioral Alterations Induced by Lead in Rats via Abrogating Oxidative Stress and the Caspase-3-Dependent Apoptotic Pathway

This work investigated the probable protective effect of an Alhagi maurorum ethanolic extract on the hepatotoxicity and neurotoxicity accompanied by neurobehavioral deficits caused by lead in rats. Rats in four groups were orally administered distilled water, ethanolic extract of A. maurorum (300 mg/kg BW daily), lead (100 mg/kg BW daily for 3 months), and lead + A. maurorum extract. The results demonstrated that lead exposure resulted in elevated locomotor activities and sensorimotor deficits associated with a decrease in brain dopamine levels. Moreover, lead exposure significantly increased liver function markers. In addition, the lead-treated rats exhibited extensive liver and brain histological changes and apoptosis. The lead treatment also triggered oxidative stress, as demonstrated by the increase in malondialdehyde (MDA) concentrations with a remarkable reduction in the activities of antioxidant enzymes, reduced glutathione (GSH) levels, and transcriptional mRNA levels of antioxidant genes in the liver and brain. Nevertheless, co-treatment with the A. maurorum extract significantly ameliorated the lead-induced toxic effects. These findings indicate that the A. maurorum extract has the ability to protect hepatic and brain tissues against lead exposure in rats through the attenuation of apoptosis and oxidative stress.

Neuron Protection by EDTA May Explain the Successful Outcomes of Toxic Metal Chelation Therapy in Neurodegenerative Diseases

Many mechanisms have been related to the etiopathogenesis of neurodegenerative diseases (NDs) such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson’s disease, and Alzheimer’s disease. In this context, the detrimental role of environmental agents has also been highlighted. Studies focused on the role of toxic metals in the pathogenesis of ND demonstrate the efficacy of treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (EDTA) in eliminating toxic metal burden in all ND patients, improving their symptoms. Lead, cadmium, aluminum, nickel, and mercury were the most important toxic metals detected in these patients. Here, I provide an updated review on the damage to neurons promoted by toxic metals and on the impact of EDTA chelation therapy in ND patients, along with the clinical description of a representative case.

Lead-exposure associated miRNAs in humans and Alzheimer’s disease as potential biomarkers of the disease and disease processes

Alzheimer’s disease (AD) is a neurodegenerative disease that eventually affects memory and behavior. The identification of biomarkers based on risk factors for AD provides insight into the disease since the exact cause of AD remains unknown. Several studies have proposed microRNAs (miRNAs) in blood as potential biomarkers for AD. Exposure to heavy metals is a potential risk factor for onset and development of AD. Blood cells of subjects that are exposed to lead detected in the circulatory system, potentially reflect molecular responses to this exposure that are similar to the response of neurons. In this study we analyzed blood cell-derived miRNAs derived from a general population as proxies of potentially AD-related mechanisms triggered by lead exposure. Subsequently, we analyzed these mechanisms in the brain tissue of AD subjects and controls. A total of four miRNAs were identified as lead exposure-associated with hsa-miR-3651, hsa-miR-150-5p and hsa-miR-664b-3p being negatively and hsa-miR-627 positively associated. In human brain derived from AD and AD control subjects all four miRNAs were detected. Moreover, two miRNAs (miR-3651, miR-664b-3p) showed significant differential expression in AD brains versus controls, in accordance with the change direction of lead exposure. The miRNAs’ gene targets were validated for expression in the human brain and were found enriched in AD-relevant pathways such as axon guidance. Moreover, we identified several AD relevant transcription factors such as CREB1 associated with the identified miRNAs. These findings suggest that the identified miRNAs are involved in the development of AD and might be useful in the development of new, less invasive biomarkers for monitoring of novel therapies or of processes involved in AD development.

Association of blood lead exposure with frailty and its components among the Chinese oldest old

Lead (Pb) is a widespread environmental contaminant, associated with a higher risk of functional impairment that can lead to frailty in older adults. However, few studies focused on the association of Pb exposure with frailty among the oldest old (aged ≥ 80 years). In this study, we aimed to assess the associations of Pb with frailty and its components in the oldest old. The included individuals were the oldest old aged ≥ 80 years who participated in a 2017 cross-sectional survey of the Healthy Aging and Biomarkers Cohort Study. Frailty was ascertained by the frailty index, which was created based on health deficits. We used logistic regression models to estimate the association of blood Pb with frailty and its components. The geometric mean and median of blood Pb were 38.51 μg/L and 36.27 μg/L among the oldest old, respectively. Compared with the first quartile of blood Pb, participants in the fourth quartile had higher risk of frailty and its components, the ORs are 1.71 (1.22-2.41), 1.99 (1.35-2.94), 1.91 (1.25-2.93), 1.57 (1.13-2.17) and 1.43 (1.05-1.96), for frailty, ADL disability, IADL disability, functional limitations, and hearing loss in the oldest old, respectively. There was a significant interaction between blood Pb and frailty in different age groups. In conclusion, our findings provide preliminary evidence that higher blood Pb may increase the risk of frailty among the oldest old by increasing the risk of disability in four physical functions: disability in ADL, disability in IADL, functional limitations, and hearing loss.

Alterations of the gut microbiota and metabolomics in children with e-waste lead exposure

BACKGROUND

A lead (Pb) exposure can alter the composition and metabolites of gut microbiota. However, few studies investigated this association in the children.

METHODS

A total of 551 children aged 3-7 years were recruited from Guiyu (the e-waste dismantling area) and Haojiang (the reference area). There were finally 70 subjects met the inclusive criteria. Blood and urinary Pb concentrations were detected by GFAAS and ICP-MS techniques. The microbiota and metabolites were measured in stool samples using 16 S rRNA MiSeq sequencing technology and gas chromatography-mass spectrometry (GC-MS), respectively.

RESULTS

Average Pb concentrations in the blood and urine of children were higher in Guiyu than in Haojiang. There were 58 kinds of differential genera and 19 types of discrepant metabolites between the two groups, and wide and significant correlations were found between them. Exposure to Pb caused the most significant differences in microbiota, metabolites, and physical development parameters between the two groups in terms of microbiota, metabolites, and physical development indicators. Sphingolipid metabolism and ion transport may also be altered by Pb exposure.

CONCLUSIONS

Exposure to Pb is associated with significant alterations in the gut microbiota and metabolome in children. More research is needed to confirm the findings of this study.

Maternal blood metal concentrations are associated with C-reactive protein and cell adhesion molecules among pregnant women in Puerto Rico

Studies have revealed a link between aberrant levels of maternal C-reactive protein (CRP) and cell adhesion molecules (CAMs) with adverse birth outcomes. Some epidemiologic studies have indicated that long-term metal exposures can modulate the levels of CRP and CAMs, but the associations between prenatal metal exposures and the levels of CRP and CAMs have yet to be studied more extensively. In this study, we assessed associations between maternal blood metal levels and CRP/CAMs among 617 pregnant women in the Puerto Rico PROTECT birth cohort.

Serum lead levels and its association with overweight and obesity

BACKGROUND

Lead (Pb) exposure has been associated with cardiovascular diseases and metabolic syndrome, nevertheless its association with obesity, type 2 diabetes, and dyslipidemia markers has been little explored in Mexico. Therefore, we evaluated the association of serum Pb levels (Pb-S), with body mass index (BMI), fasting plasma glucose (FPG), total cholesterol (TC), and triglycerides (TG).

METHODS

A cross-sectional study was performed on 85 Mexican adults (57 women and 28 men). BMI was calculated, while FPG, TC, and TG were measured by the enzymatic colorimetric method. Total Pb-S levels were measured using inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

The study population was 20.3 ± 1.9 years old, showed an average of Pb-S of 0.0982 ± 0.068 μg dL^-1, and presented a frequency of overweight (OW) and obesity (OB) of 50.5% and 18.8%, respectively. Men had higher average FPG than women (Women= 83.930 ± 5.662 vs Men= 84.953 ± 6.495; p = 0.037). When we analyzed anthropometric and clinical variables, Pb-S and frequency of OW and OB were observed to increase within the categories of Pb-S tertiles (<0.001). The averages of Pb-S were 0.051 ± 0.035 µg dL^-1, 0.107 ± 0.067 µg dL^-1, and 0.151 ± 0.063 µg dL^-1 for individuals with normal weight (NW), OW, and OB, respectively. In addition, an analysis adjusted for age and sex shows Pb-S is positively associated with BMI (β = 2.76 ± 0.498, p = <0.001).

CONCLUSION

Our results evidence a significant association between Pb-S and the increase of BMI in Mexican adults and highlight the important health impact that may represent environmental Pb exposure.

An evaluation of the effects of ascorbic acid on the endothelium of coronary and aorta arteries in lead-intoxicated rabbits

Objectives:

Lead exposure has destructive effects on some organs. It may produce a variety of toxic effects on endothelial cells of the vascular system. Any changes or damages to endothelial cells may lead to cardiovascular diseases, particularly the formation of atherosclerotic plaques. The aim of this study was to determine the ameliorative effects of ascorbic acid on the endothelium of coronary and aorta arteries in lead-exposed rabbits.

Methods:

In this study, 30 white male rabbits of New Zealand race (weighing about 1.6–2 kg and 5 months old) were used and divided randomly into three groups: Group 1 (N = 10) that served as the control and received water and normal diet, Group 2 (N = 10) was exposed to lead acetate 547 ppm (5 mg/L) daily for 40 days, and Group 3 (N = 10) received vitamin C (500 mg/kg) and underwent the same duration of lead exposure (5 mg/L) daily for 40 days. The levels of cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein were measured using spectrophotometry, and the level of blood lead was calculated using a lead analyzer (Magellan Diagnostics, USA). The animals were anesthetized by pentobarbital (50 mg/kg). Subsequently, they were sacrificed, and their thoracic aortas and coronary arteries were removed. Then fixation, tissue processing, histological sectioning, and H & E staining were carried out. Finally, the sections were studied using light microscopy. The results were analyzed using the Mann–Whitney test.

Results:

The results indicated that ascorbic acid could reduce the destructive effects of lead on vascular endothelial cells and prevent the formation of atherosclerotic plaques in coronary and aorta arteries.

Conclusion:

The results of this study confirm the beneficial effects of ascorbic acid against the destructive effects of lead on vascular endothelial cells. Hence, it could be proposed as a potential prophylactic treatment for the amelioration of lead toxicity, prevention of atherosclerosis, and improvement of endothelial cells dysfunction.

Blood Lead Levels and Risk of Deaths from Cardiovascular Disease

Environmental exposure could be an important modifiable risk factor for cardiovascular disease (CVD). In this study, we investigated the relation between lead exposure, measured as blood lead levels (BLLs) and CVD mortality in a national cohort. A total of 15,036 adults aged ≥19 who participated in the National Health and Nutrition Examination Survey (1988 to 1994) as the baseline examination were followed up through December 31, 2010. Adjusted hazard ratios (HRs) derived from Cox proportional hazard regressions were used to estimate the risk of dying from CVD in association with BLLs. Cardiovascular mortality was 3.76, 8.11, and 14.77 per 1,000 person-years for patients in low, moderate, and high BLLs, respectively. After adjusting for potential confounders, patients in the high lead level had a significantly increased risk of death from all CVD (HR 1.35, 95% confidence interval 1.03 to 1.77), compared with those with low level. Participants in both moderate and high lead levels showed a significantly increased risk of death from heart disease, with an HR of 1.37 (1.04 to 1.81) and 1.60 (1.21 to 2.13), respectively. A significant linear association with all CVD and heart disease deaths was also seen with an HR of 1.08 (1.00 to 1.16) and 1.09 (1.02 to 1.16), respectively, per 1-unit increase in BLLs. In conclusion, the study demonstrates that increasing BLLs were associated with an increased risk of cardiovascular deaths, especially from heart disease. This further supports the possible cardiovascular effects that lead poses on patients at low levels of exposure and the importance of further reducing lead exposure in the general population.

Prenatal lead exposure and childhood lung function: Influence of maternal cortisol and child sex

INTRODUCTION

Maternal hypothalamic-pituitary-adrenal (HPA) axis disruption in pregnancy may contribute to the programming of childhood respiratory disease and may modify the effect of chemical toxins, like lead (Pb), on lung development. Child sex may further modify these effects. We sought to prospectively examine associations between maternal HPA axis disruption, prenatal Pb and childhood lung function and explore potential effect modification by maternal cortisol and child sex on the association between prenatal Pb and lung function outcomes.

MATERIALS AND METHODS

Analyses included 222 mothers and children enrolled in a longitudinal birth cohort study in Mexico City. Maternal diurnal salivary cortisol was assessed in pregnancy; cortisol awakening response (CAR) and diurnal slope were calculated. Blood Pb was measured during the second trimester of pregnancy. Post-bronchodilator lung function was tested at ages 8-11 years. Associations were modeled using generalized linear models with interaction terms, adjusting for covariates.

RESULTS

A higher (flatter) diurnal slope was associated with lower FEV₁/FVC ratio (β: 0.433, 95%CI [-0.766, -0.101]). We did not find any main effect associations between prenatal Pb and lung function outcomes. We report an interaction between Pb and cortisol in relation to FEV₁/FVC and FEF_25-75% (p_interaction<0.05 for all). Higher prenatal Pb was associated with reduced FEV₁/FVC only in children whose mothers had a high CAR. Higher prenatal Pb was also associated with reduced FEV₁/FVC and FEF_25-75% in mothers with a flatter diurnal slope. A 3-way interaction between prenatal Pb, CAR and sex on FEV₁/FVC, indicated that boys born to women with high CAR and higher prenatal Pb levels had lower FEV₁/FVC ratios (p_interaction = 0.067).

CONCLUSIONS

Associations between prenatal Pb and childhood lung function were modified by disrupted maternal cortisol in pregnancy and child sex. These findings underscore the need to consider complex interactions to fully elucidate effects of prenatal Pb exposure on childhood lung function.

Associations of blood and urinary heavy metals with rheumatoid arthritis risk among adults in NHANES, 1999-2018

Heavy metals exposure has been widely recognized as a risk factor for human health. However, limited information is available about the impacts of heavy metals on rheumatoid arthritis (RA). Herein, we estimated the associations of 3 blood and 11 urinary metals with the risk of RA among 49830 U.S. adults from the National Health and Nutrition Examination Survey (NHANES), 1999-2018. In the single-exposure model, blood cadmium (Cd) and lead (Pb), urinary Cd, Pb, antimony (Sb), tungsten (Tu), and uranium (Ur) were identified to be positively associated with RA risk. Furthermore, weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR) analyses consistently showed that both blood and urinary metals-mixed exposure were positively correlated with the risk of RA, and highlighted that Cd and Pb were responsible for the outcomes. Such associations were more evident in the young and middle-aged population. These findings indicated that exposure to heavy metals increased RA risk, and advanced the identification of risk factors for RA.

Association between occupational lead exposure and immunotoxicity markers: A systematic review and meta-analysis

Recent evidences suggest the role of chronic lead (Pb) exposure in altering immunological parameters. Present study aimed to systematically review existing literature and synthesize quantitative evidence on the association between chronic Pb exposure and changes in immunological markers. Observational studies reporting immunological markers such as leukocyte derivative counts (CD3⁺, CD4⁺, CD8⁺, CD45⁺, CD56⁺, lymphocyte, and total leukocyte), cytokine, Immunoglobulin (Igs), C-reactive protein (CRP) among Pb-exposed and unexposed controls were systematically searched from PubMed, Scopus and Embase digital databases from inception to January 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adhered during systematic review. Mean differences in the immunological markers between Pb-exposed and control groups were pooled using random-effects model. The heterogeneity was assessed using Cochran-Q test and I² statistic. The review included forty studies reporting immunological markers in Pb-exposed and unexposed control groups. The occupational Pb-exposed group exhibited significantly higher BLL, impaired immunological markers, characterized by a marginal lowering in lymphocyte count, lymphocyte subsets (CD3⁺, CD4⁺, CD4⁺/CD8⁺ ratio), IFN-γ and IgG levels, while CD8⁺, IgM, IgA, IgE, and cytokines (IL-4, IL-6, IL-10, and TNF-α) exhibited a trend of higher values in comparison to the control group. Further, inflammatory marker viz., total leukocyte count was significantly higher among Pb-exposed. The included studies exhibited high levels of heterogeneity. In conclusion, Occupational Pb exposure alters the immunological markers such as the circulating cytokines and leukocyte counts. However, high-quality, multicentered studies are required to strengthen present observations and further understand the Pb's role on the immune system. Prospero Registration ID: CRD42021228252.

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.

Genetically determined blood lead is associated with reduced renal function amongst individuals with type 2 diabetes mellitus: insight from Mendelian Randomisation

Some observational studies indicate a link between blood lead and kidney function although results remain controversial. In this study, Mendelian randomisation (MR) analysis was applied to obtain unconfounded estimates of the casual association of genetically determined blood lead with estimated glomerular filtration rate (eGFR) and the risk of chronic kidney disease (CKD). Data from the largest genome-wide association studies (GWAS) on blood lead, eGFR and CKD, from predominantly ethnically European populations, were analysed in total, as well as separately in individuals with or without type 2 diabetes mellitus. Inverse variance weighted (IVW) method, weighted median (WM)-based method, MR-Egger, MR-Pleiotropy RESidual Sum and Outlier (PRESSO) as well as the leave-one-out method were applied. In a general population, lifetime blood lead levels had no significant effect on risk of CKD (IVW: p = 0.652) and eGFR (IVW: p = 0.668). After grouping by type 2 diabetes status (no diabetes vs. diabetes), genetically higher levels of blood lead had a significant negative impact among subjects with type 2 diabetes (IVW = Beta: -0.03416, p = 0.0132) but not in subjects without (IVW: p = 0.823), with low likelihood of heterogeneity for any estimates (IVW p > 0.158). MR-PRESSO did not highlight any outliers. Pleiotropy test, with very negligible intercept and insignificant p-value, indicated a low likelihood of pleiotropy for all estimations. The leave-one-out method demonstrated that links were not driven by a single SNP. Our results show, for the first time, that among subjects with type 2 diabetes, higher blood lead levels are potentially related to less favourable renal function. Further studies are needed to confirm our results. KEY MESSAGES: What is already known about this subject? Chronic kidney disease is associated with unfavourable lifestyle behaviours and conditions such as type 2 diabetes. Observational studies have reported an association between blood lead and reduced estimated glomerular filtration rate, but the relationship between lead exposure and renal function remains controversial. What is the key question? Using Mendelian randomisation with data from 5433 individuals from the UK and Australian populations, does genetically determined blood lead have a potentially causal effect on estimated glomerular filtration rate and the risk of chronic kidney disease? What are the new findings? Blood lead levels have a potentially causal effect on reduced renal function in individuals with type 2 diabetes. In subjects without diabetes, no such causal relationship was identified. How might this impact on clinical practice in the foreseeable future? This highlights the risk of elevated blood lead, for example, due to environmental exposure, amongst those with type 2 diabetes, which may predispose them to impaired renal function.

Effect of occupational co-exposure to lead and cadmium on selected immunomodulatory cytokines

Occupational exposure to heavy metals like lead (Pb) and cadmium (Cd) is associated with the development of several diseases. The objective of this study was to determine the effect of occupational co-exposure to Pb and Cd on the blood levels of selected immune-modulatory cytokines related to T helper (Th), that is, Th1, interleukin-2 (IL-2), Th2, (IL-4 and IL-10), and Th17, (IL-17) cells. The study comprised 207 individuals divided into two groups: exposed (n = 110) and nonexposed (n = 97). Blood Pb and Cd were determined using Graphite Furnace Atomic Absorption Spectroscopy, and serum levels of cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The study revealed significantly higher blood Pb and Cd levels in the exposed group. A significant decrease in Th1 cytokine-IL-2 and Th2 cytokine-IL-10 was found, while IL-4 (Th2 cytokine) and IL-17 (Th17) levels were higher in the exposed group. In the mixed exposure analysis, among all the selected cytokines, IL-4 levels were significantly different between individuals having higher levels of both Pb and Cd versus lower levels of Pb and Cd. While IL-2 levels were highest among the low Pb and Cd group, the IL-17 levels were highest among individuals with higher Cd levels. The study demonstrated that co-exposure to low levels of Pb and Cd might have an immune-modulatory effect. The data suggested a metal-induced pro-inflammatory immune response.