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Sampson MM, Morgan RK, Sloan SA, Bakulski KM. Single-cell investigation of lead toxicity from neurodevelopment to neurodegeneration: Current review and future opportunities. CURRENT OPINION IN TOXICOLOGY 2024; 38:100464. [PMID: 39086983 PMCID: PMC11290315 DOI: 10.1016/j.cotox.2024.100464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Human exposure to the metal lead (Pb) is prevalent and associated with adverse neurodevelopmental and neurodegenerative outcomes. Pb disrupts normal brain function by inducing oxidative stress and neuroinflammation, altering cellular metabolism, and displacing essential metals. Prior studies on the molecular impacts of Pb have examined bulk tissues, which collapse information across all cell types, or in targeted cells, which are limited to cell autonomous effects. These approaches are unable to represent the complete biological implications of Pb exposure because the brain is a cooperative network of highly heterogeneous cells, with cellular diversity and proportions shifting throughout development, by brain region, and with disease. New technologies are necessary to investigate whether Pb and other environmental exposures alter cell composition in the brain and whether they cause molecular changes in a cell-type-specific manner. Cutting-edge, single-cell approaches now enable research resolving cell-type-specific effects from bulk tissues. This article reviews existing Pb neurotoxicology studies with genome-wide molecular signatures and provides a path forward for the field to implement single-cell approaches with practical recommendations.
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Affiliation(s)
- Maureen M Sampson
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Rachel K Morgan
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Steven A Sloan
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Kelly M Bakulski
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA
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Yu G, Wu L, Su Q, Ji X, Zhou J, Wu S, Tang Y, Li H. Neurotoxic effects of heavy metal pollutants in the environment: Focusing on epigenetic mechanisms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123563. [PMID: 38355086 DOI: 10.1016/j.envpol.2024.123563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 02/04/2024] [Accepted: 02/11/2024] [Indexed: 02/16/2024]
Abstract
The pollution of heavy metals (HMs) in the environment is a significant global environmental issue, characterized by its extensive distribution, severe contamination, and profound ecological impacts. Excessive exposure to heavy metal pollutants can damage the nervous system. However, the mechanisms underlying the neurotoxicity of most heavy metals are not completely understood. Epigenetics is defined as a heritable change in gene function that can influence gene and subsequent protein expression levels without altering the DNA sequence. Growing evidence indicates that heavy metals can induce neurotoxic effects by triggering epigenetic changes and disrupting the epigenome. Compared with genetic changes, epigenetic alterations are more easily reversible. Epigenetic reprogramming techniques, drugs, and certain nutrients targeting specific epigenetic mechanisms involved in gene expression regulation are emerging as potential preventive or therapeutic tools for diseases. Therefore, this review provides a comprehensive overview of epigenetic modifications encompassing DNA/RNA methylation, histone modifications, and non-coding RNAs in the nervous system, elucidating their association with various heavy metal exposures. These primarily include manganese (Mn), mercury (Hg), lead (Pb), cobalt (Co), cadmium (Cd), nickel (Ni), sliver (Ag), toxic metalloids arsenic (As), and etc. The potential epigenetic mechanisms in the etiology, precision prevention, and target therapy of various neurodevelopmental disorders or different neurodegenerative diseases are emphasized. In addition, the current gaps in research and future areas of study are discussed. From a perspective on epigenetics, this review offers novel insights for prevention and treatment of neurotoxicity induced by heavy metal pollutants.
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Affiliation(s)
- Guangxia Yu
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China; Department of Preventive Medicine, School of Public Health, Fujian Medical University, Fuzhou 350122, China
| | - Lingyan Wu
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China
| | - Qianqian Su
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China
| | - Xianqi Ji
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China
| | - Jinfu Zhou
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China; Fujian Maternity and Child Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fuzhou 350001, China
| | - Siying Wu
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China; Department of Epidemiology and Health Statistics, School of Public Health, Fujian Medical University, Fuzhou 350122, China
| | - Ying Tang
- Fujian Center for Prevention and Control Occupational Diseases and Chemical Poisoning, Fuzhou 350125, China
| | - Huangyuan Li
- Key Lab of Environment and Health, School of Public Health, Fujian Medical University, Fuzhou 350122, China; Department of Preventive Medicine, School of Public Health, Fujian Medical University, Fuzhou 350122, China.
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Xie J, Wu S, Szadowski H, Min S, Yang Y, Bowman AB, Rochet JC, Freeman JL, Yuan C. Developmental Pb exposure increases AD risk via altered intracellular Ca 2+ homeostasis in hiPSC-derived cortical neurons. J Biol Chem 2023; 299:105023. [PMID: 37423307 PMCID: PMC10413359 DOI: 10.1016/j.jbc.2023.105023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023] Open
Abstract
Exposure to environmental chemicals such as lead (Pb) during vulnerable developmental periods can result in adverse health outcomes later in life. Human cohort studies have demonstrated associations between developmental Pb exposure and Alzheimer's disease (AD) onset in later life which were further corroborated by findings from animal studies. The molecular pathway linking developmental Pb exposure and increased AD risk, however, remains elusive. In this work, we used human iPSC-derived cortical neurons as a model system to study the effects of Pb exposure on AD-like pathogenesis in human cortical neurons. We exposed neural progenitor cells derived from human iPSC to 0, 15, and 50 ppb Pb for 48 h, removed Pb-containing medium, and further differentiated them into cortical neurons. Immunofluorescence, Western blotting, RNA-sequencing, ELISA, and FRET reporter cell lines were used to determine changes in AD-like pathogenesis in differentiated cortical neurons. Exposing neural progenitor cells to low-dose Pb, mimicking a developmental exposure, can result in altered neurite morphology. Differentiated neurons exhibit altered calcium homeostasis, synaptic plasticity, and epigenetic landscape along with elevated AD-like pathogenesis markers, including phosphorylated tau, tau aggregates, and Aβ42/40. Collectively, our findings provide an evidence base for Ca dysregulation caused by developmental Pb exposure as a plausible molecular mechanism accounting for increased AD risk in populations with developmental Pb exposure.
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Affiliation(s)
- Junkai Xie
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Shichen Wu
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Hailey Szadowski
- Agriculture and Biological Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Sehong Min
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA
| | - Aaron B Bowman
- Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Jean-Christophe Rochet
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA
| | - Jennifer L Freeman
- Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; School of Health Sciences, Purdue University, West Lafayette, Indiana, USA; Purdue Center of Cancer Research, Purdue University, West Lafayette, Indiana, USA
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; Purdue Center of Cancer Research, Purdue University, West Lafayette, Indiana, USA.
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Jenson TE, Bakulski KM, Wesp L, Dookeran K, Driscoll I, Kalkbrenner AE. Racialized experience, biomarkers of lead exposure, and later-life cognition: a mediation analysis. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.04.22.23288920. [PMID: 37163072 PMCID: PMC10168513 DOI: 10.1101/2023.04.22.23288920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We evaluated the role of the neurotoxicant lead (Pb) in mediating racial disparities in later-life cognition in 1,085 non-Hispanic Black and 2,839 non-Hispanic white participants in NHANES (1999-2002, 2011-2014) 60+ years of age. We operationalized Black race as a marker for the experience of racialization and exposure to systemic racism. We estimated patella bone Pb via predictive models using blood Pb and demographics. Concurrent cognition (processing speed, sustained attention, working memory) was measured by the Digit Symbol Substitution Test (DSST) and a global measure combining four cognitive tests. To obtain the portion mediated, we used regression coefficients (race on Pb * Pb on cognitive score)/(race on cognitive score), adjusting for age, NHANES cycle, and sample weights. Other confounder adjustment (education, poverty income ratio, smoking) was limited to the mediator-outcome (i.e., Pb-cognition) pathway because these factors do not lie upstream of race and so cannot confound associations with race. Pb was estimated to mediate 0.6% of the association between race and global cognition, and 4% of the DSST. Our results suggest that later-life cognitive health disparities may be impacted by avoidable lead exposure driven by environmental injustice, noting that a large proportion of the pathway of systemic racism harming cognition remains.
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Affiliation(s)
- Tara E. Jenson
- Department of Environmental Health Sciences, Zilber School of Public Health, University of Wisconsin – Milwaukee, Milwaukee, WI, USA
| | - Kelly M. Bakulski
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Linda Wesp
- College of Nursing, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | - Keith Dookeran
- Department of Epidemiology, Zilber School of Public Health, University of Wisconsin – Milwaukee, Milwaukee, WI, USA
| | - Ira Driscoll
- Alzheimer's Disease Research Center, University of Wisconsin - Madison, Madison, WI, USA
- Geriatrics, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Amy E. Kalkbrenner
- Department of Environmental Health Sciences, Zilber School of Public Health, University of Wisconsin – Milwaukee, Milwaukee, WI, USA
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Migliore L, Coppedè F. Gene-environment interactions in Alzheimer disease: the emerging role of epigenetics. Nat Rev Neurol 2022; 18:643-660. [PMID: 36180553 DOI: 10.1038/s41582-022-00714-w] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2022] [Indexed: 12/15/2022]
Abstract
With the exception of a few monogenic forms, Alzheimer disease (AD) has a complex aetiology that is likely to involve multiple susceptibility genes and environmental factors. The role of environmental factors is difficult to determine and, until a few years ago, the molecular mechanisms underlying gene-environment (G × E) interactions in AD were largely unknown. Here, we review evidence that has emerged over the past two decades to explain how environmental factors, such as diet, lifestyle, alcohol, smoking and pollutants, might interact with the human genome. In particular, we discuss how various environmental AD risk factors can induce epigenetic modifications of key AD-related genes and pathways and consider how epigenetic mechanisms could contribute to the effects of oxidative stress on AD onset. Studies on early-life exposures are helping to uncover critical time windows of sensitivity to epigenetic influences from environmental factors, thereby laying the foundations for future primary preventative approaches. We conclude that epigenetic modifications need to be considered when assessing G × E interactions in AD.
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Affiliation(s)
- Lucia Migliore
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy. .,Department of Laboratory Medicine, Pisa University Hospital, Pisa, Italy.
| | - Fabio Coppedè
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
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Li C, Zhang Y, Liang J, Wu C, Zou X. Assessing the Association Between Lead Pollution and Risk of Alzheimer’s Disease by Integrating Multigenomics. Front Neurosci 2022; 16:880105. [PMID: 35937890 PMCID: PMC9353516 DOI: 10.3389/fnins.2022.880105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/30/2022] [Indexed: 12/04/2022] Open
Abstract
Alzheimer’s disease (AD) is a life-threatening neurodegenerative disease of the elderly. In recent observations, exposure to heavy metals environmental may increase the risk of AD. However, there are few studies on the causal relationship between heavy metal exposure and AD. In this study, we integrated two large-scale summaries of AD genome-wide association study (GWAS) datasets and a blood lead level GWAS dataset and performed the two-sample Mendelian randomization analysis to assess the causality of blood lead level and AD risk. The results showed that there is a significantly positive causality between blood lead level and AD risk both in the inverse-variance weighted (IVW) model and the weighted median estimator (WME) model. An independent additional verification also reached a consistent conclusion. These findings further confirm the conclusions of previous studies and improve the understanding of the relationship between AD pathogenesis and the toxicity of lead in environmental pollution.
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Affiliation(s)
- Chunying Li
- Institute of Fungus Resources, College of Life Sciences, Guizhou University, Guiyang, China
- Department of Environmental Engineering, Chongqing Vocational College of Resources and Environmental Protection, Chongqing, China
| | - Yuwei Zhang
- Institute of Fungus Resources, College of Life Sciences, Guizhou University, Guiyang, China
| | - Jiandong Liang
- Basic Medical School, Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Changyan Wu
- Basic Medical School, Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Xiao Zou
- Institute of Fungus Resources, College of Life Sciences, Guizhou University, Guiyang, China
- *Correspondence: Xiao Zou,
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Laouali N, Benmarhnia T, Lanphear BP, Weuve J, Mascari M, Boutron-Ruault MC, Oulhote Y. Association between blood metals mixtures concentrations and cognitive performance, and effect modification by diet in older US adults. Environ Epidemiol 2022; 6:e192. [PMID: 35169670 PMCID: PMC8835643 DOI: 10.1097/ee9.0000000000000192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 12/14/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Chronic exposure to heavy metals has been associated with adverse neurological outcomes in older adults. Inflammatory processes are suspected as an underlying pathway by which metals exert their neurotoxicity. In parallel, a diet rich in antioxidant and anti-inflammatory components may protect against chronic inflammation. OBJECTIVES We examined the associations of blood concentrations of lead, cadmium, and manganese as a mixture with cognitive performance in older US adults and potential modification of these associations by diet as measured by the Healthy Eating Index 2015 (HEI-2015) and the Adapted Dietary Inflammatory Index (ADII). METHODS We used data on 1,777 adults ≥60 years old from the US National Health and Nutrition Examination Survey (NHANES; 2011-2014). We derived the ADII and the HEI-2015 from two nonconsecutive 24-hour diet recalls. Cognitive performance was measured by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning subtest, the animal fluency test, and the Digit Symbol Substitution Test (DSST). We also constructed a composite z-score reflecting overall cognitive performance. We used quantile g-computation to evaluate the joint associations of a mixture of metals with cognitive performance test scores. We also evaluated effect modification by sex and diet quality indices using Cochran Q tests. RESULTS The median (interquartile range) of blood metals were 0.38 μg/L (0.35), 14.70 μg/L (11.70), and 8.74 μg/L (4.06) for cadmium, lead, and manganese, respectively. Increasing blood concentrations of all metals by one quartile was associated with a decrease in overall cognitive performance (-0.04; 95% confidence interval [CI] = -0.09, 0.02), CERAD (-0.04; 95% CI = -0.12, 0.03), animal fluency (-0.02; 95% CI, -0.11, 0.06), and DSST (-0.05; 95% CI = -0.11, 0.02) test scores. These associations were more pronounced in adults with high pro-inflammatory or low-diet quality and null or positive though imprecise associations in participants with a high anti-inflammatory. These associations also varied by sex with inverse associations in men and positive associations in women. CONCLUSIONS Our findings suggest that adherence to an antioxidant and anti-inflammatory diet may prevent blood metals adverse cognitive effects among older adults. If confirmed, strategies based on diet could provide a potential complementary and efficient approach to counteract effects of environmental pollutants.
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Affiliation(s)
- Nasser Laouali
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts at Amherst, Amherst, Massachusetts
- Department of Family Medicine and Public Health & Scripps Institution of Oceanography, University of California, San Diego, California
- CESP UMR1018, Université Paris-Saclay, UVSQ, Inserm, Gustave Roussy, Villejuif, Paris, France
| | - Tarik Benmarhnia
- Department of Family Medicine and Public Health & Scripps Institution of Oceanography, University of California, San Diego, California
| | - Bruce P. Lanphear
- Child and Family Research Institute, BC Children’s Hospital, Vancouver, British Columbia, Canada
- Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jennifer Weuve
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - Michael Mascari
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts at Amherst, Amherst, Massachusetts
| | | | - Youssef Oulhote
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts at Amherst, Amherst, Massachusetts
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8
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Salkov VN, Khudoerkov RM. [The role of aluminum and lead in the development of Alzheimer's and Parkinson's diseases]. Arkh Patol 2021; 83:56-61. [PMID: 34041898 DOI: 10.17116/patol20218303156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The article summarizes the data available in the literature on the toxic effects of aluminum and lead on the human brain and assesses the relationship of these effects to the etiopathogenesis of the most common neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. The accumulation of ions of these metals in the brain structures leads to chronic intoxication that is manifested by the morphological signs that are typical for Alzheimer's disease, such as deposits of β-amyloid and τ-protein mainly in the frontal and temporal regions of the cortex, and for Parkinson's disease, such as degeneration of dopamine neurons in the substantia nigra and their accumulation of α-synuclein. The most likely forms of participation of aluminum and lead ions in the mechanisms of neurodegeneration are the replacement of bivalent metal ions necessary for brain functioning, oxidative stress initiation, epigenetic modifications of histones, and increased expression of noncoding ribonucleic acids.
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Affiliation(s)
- V N Salkov
- Research Center of Neurology, Moscow, Russia
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9
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Syeda T, Cannon JR. Environmental exposures and the etiopathogenesis of Alzheimer's disease: The potential role of BACE1 as a critical neurotoxic target. J Biochem Mol Toxicol 2021; 35:e22694. [PMID: 33393683 DOI: 10.1002/jbt.22694] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/18/2020] [Accepted: 12/22/2020] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) is a major public health crisis due to devastating cognitive symptoms, a lack of curative treatments, and increasing prevalence. Most cases are sporadic (>95% of cases) after the age of 65 years, implicating an important role of environmental factors in disease pathogenesis. Environmental neurotoxicants have been implicated in neurodegenerative disorders including Parkinson's Disease and AD. Animal models of AD and in vitro studies have shed light on potential neuropathological mechanisms, yet the biochemical and molecular underpinnings of AD-relevant environmental neurotoxicity remain poorly understood. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is a potentially critical pathogenic target of environmentally induced neurotoxicity. BACE1 clearly has a critical role in AD pathophysiology: It is required for amyloid beta production and expression and activity of BACE1 are increased in the AD brain. Though the literature on BACE1 in response to environmental insults is limited, current studies, along with extensive AD neurobiology literature suggest that BACE1 deserves attention as an important neurotoxic target. Here, we critically review research on environmental neurotoxicants such as metals, pesticides, herbicides, fungicides, polyfluoroalkyl substances, heterocyclic aromatic amines, advanced glycation end products, and acrolein that modulate BACE1 and potential mechanisms of action. Though more research is needed to clearly understand whether BACE1 is a critical mediator of AD-relevant neurotoxicity, available reports provide convincing evidence that BACE1 is altered by environmental risk factors associated with AD pathology, implying that BACE1 inhibition and its use as a biomarker should be considered in AD management and research.
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Affiliation(s)
- Tauqeerunnisa Syeda
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana, USA
| | - Jason R Cannon
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, Indiana, USA
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Werder EJ, Engel LS, Curry MD, Sandler DP. Selenium modifies associations between multiple metals and neurologic symptoms in Gulf states residents. Environ Epidemiol 2020; 4:e115. [PMID: 33336134 PMCID: PMC7727467 DOI: 10.1097/ee9.0000000000000115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/23/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Metals have been shown to have a wide range of neurologic effects across the life course, but most studies consider neurodevelopment or neurodegenerative diseases in older adults. We investigated exposure to metals during adulthood in association with subclinical neurologic endpoints, considering the metals individually and as a mixture, and potential interactions among exposures. METHODS We measured blood levels of cadmium, lead, mercury, manganese, and selenium in 1007 Gulf state residents and estimated cross-sectional associations between ranked levels of blood metals and the presence of self-reported neurologic symptoms. Single pollutant models were mutually adjusted for other metals and we used quantile g-computation to evaluate associations with exposure to the combined mixture. In stratified analyses, we assessed heterogeneity by smoking and blood selenium. RESULTS The highest quartile of cadmium was associated with a higher prevalence of central nervous system symptoms (prevalence ratio [PR] = 1.50; 95% confidence interval [CI] = 1.13, 1.99), with stronger associations among nonsmokers (PR = 1.63; 95% CI = 1.11, 2.38) and those with low selenium (PR = 2.29, 95% CI = 1.50, 3.49). Selenium also modified associations between lead and peripheral nervous system symptoms, with increased symptoms in the low selenium group at all quartiles of exposure (P-trend = 0.07). Conversely, those with the highest co-exposure to mercury and selenium had reduced neurologic symptoms (PR = 0.73, 95% CI = 0.55, 0.96). Results of the mixture analysis were consistent with single chemical results. CONCLUSIONS Cadmium exhibited the most consistent relationship with increased neurologic symptoms, though lead was an important exposure in subgroup analyses. Selenium may modify subclinical neurotoxic effects of metals at non-occupational levels in adults.
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Affiliation(s)
- Emily J. Werder
- Epidemiology Branch, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina
| | - Lawrence S. Engel
- Epidemiology Branch, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina
- Department of Epidemiology, UNC Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | | | - Dale P. Sandler
- Epidemiology Branch, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina
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Wang T, Zhang J, Xu Y. Epigenetic Basis of Lead-Induced Neurological Disorders. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17134878. [PMID: 32645824 PMCID: PMC7370007 DOI: 10.3390/ijerph17134878] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/01/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023]
Abstract
Environmental lead (Pb) exposure is closely associated with pathogenesis of a range of neurological disorders, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), attention deficit/hyperactivity disorder (ADHD), etc. Epigenetic machinery modulates neural development and activities, while faulty epigenetic regulation contributes to the diverse forms of CNS (central nervous system) abnormalities and diseases. As a potent epigenetic modifier, lead is thought to cause neurological disorders through modulating epigenetic mechanisms. Specifically, increasing evidence linked aberrant DNA methylations, histone modifications as well as ncRNAs (non-coding RNAs) with AD cases, among which circRNA (circular RNA) stands out as a new and promising field for association studies. In 23-year-old primates with developmental lead treatment, Zawia group discovered a variety of epigenetic changes relating to AD pathogenesis. This is a direct evidence implicating epigenetic basis in lead-induced AD animals with an entire lifespan. Additionally, some epigenetic molecules associated with AD etiology were also known to respond to chronic lead exposure in comparable disease models, indicating potentially interlaced mechanisms with respect to the studied neurotoxic and pathological events. Of note, epigenetic molecules acted via globally or selectively influencing the expression of disease-related genes. Compared to AD, the association of lead exposure with other neurological disorders were primarily supported by epidemiological survey, with fewer reports connecting epigenetic regulators with lead-induced pathogenesis. Some pharmaceuticals, such as HDAC (histone deacetylase) inhibitors and DNA methylation inhibitors, were developed to deal with CNS disease by targeting epigenetic components. Still, understandings are insufficient regarding the cause–consequence relations of epigenetic factors and neurological illness. Therefore, clear evidence should be provided in future investigations to address detailed roles of novel epigenetic factors in lead-induced neurological disorders, and efforts of developing specific epigenetic therapeutics should be appraised.
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Affiliation(s)
| | | | - Yi Xu
- Correspondence: ; Tel.: +86-183-2613-5046
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12
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Early-life Pb exposure as a potential risk factor for Alzheimer’s disease: are there hazards for the Mexican population? J Biol Inorg Chem 2019; 24:1285-1303. [DOI: 10.1007/s00775-019-01739-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/25/2019] [Indexed: 12/30/2022]
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