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Mani MS, Kabekkodu SP, Joshi MB, Dsouza HS. Ecogenetics of lead toxicity and its influence on risk assessment. Hum Exp Toxicol 2019; 38:1031-1059. [PMID: 31117811 DOI: 10.1177/0960327119851253] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
Lead (Pb) toxicity is a public health problem affecting millions worldwide. Advances in 'omic' technology have paved the way to toxico-genomics which is currently revolutionizing the understanding of interindividual variations in susceptibility to Pb toxicity and its functional consequences to exposure. Our objective was to identify, comprehensively analyze, and curate all the potential genetic and epigenetic biomarkers studied to date in relation to Pb toxicity and its association with diseases. We screened a volume of research articles that focused on Pb toxicity and its association with genetic and epigenetic signatures in the perspective of occupational and environmental Pb exposure. Due to wide variations in population size, ethnicity, age-groups, and source of exposure in different studies, researchers continue to be skeptical on the topic of the influence of genetic variations in Pb toxicity. However, surface knowledge of the underlying genetic factors will aid in elucidating the mechanism of action of Pb. Moreover, in recent years, the application of epigenetics in Pb toxicity has become a promising area in toxicology to understand the influence of epigenetic mechanisms such as DNA methylation, chromatin remodeling, and small RNAs for the regulation of genes in response to Pb exposure during early life. Growing evidences of ecogenetic understanding (both genetic and epigenetic processes) in a dose-dependent manner may help uncover the mechanism of action of Pb and in the identification of susceptible groups. Such studies will further help in refining uncertainty factors and in addressing risk assessment of Pb poisoning.
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Affiliation(s)
- M S Mani
- 1 Department of Radiation Biology and Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - S P Kabekkodu
- 2 Department of Cellular and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - M B Joshi
- 3 Department of Ageing, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - H S Dsouza
- 1 Department of Radiation Biology and Toxicology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
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Ciesielski TH, Schwartz J, Bellinger DC, Hauser R, Amarasiriwardena C, Sparrow D, Wright RO. Iron-processing genotypes, nutrient intakes, and cadmium levels in the Normative Aging Study: Evidence of sensitive subpopulations in cadmium risk assessment. ENVIRONMENT INTERNATIONAL 2018; 119:527-535. [PMID: 30059941 DOI: 10.1016/j.envint.2018.06.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Because iron and cadmium share common transport mechanisms, iron-processing protein variants such as HFE C282Y, HFE H63D, and Transferrin P570S may influence cadmium metabolism. Our aim was to evaluate associations between common HFE and Transferrin polymorphisms and toenail cadmium levels among older men. METHODS In a longitudinal cohort of men age 51-97, the Normative Aging Study (NAS), we evaluated toenail cadmium concentrations and missense single nucleotide polymorphisms (SNPs) in the HFE and Transferrin genes. We fit age-adjusted models to estimate associations between genotypes and toenail cadmium concentrations. We then considered potential interactions with smoking status, hemoglobin, and nutritional intakes known to modulate cadmium absorption. For the significant interactions, we also evaluated genotype specific effect estimates. RESULTS HFE and Transferrin genotypes were not associated with toenail cadmium concentrations in the main effect analyses, but there were significant interactions between HFE H63D and hemoglobin (pinteraction = 0.021), as well as HFE H63D and vitamin C intake (pinteraction = 0.048). Genotype specific effect estimates suggested: 1) an inverse relationship between hemoglobin and cadmium levels among HFE H63D homozygotes, and 2) an inverse relationship between vitamin C intake and cadmium levels that strengthens with the number of HFE H63D variant alleles a subject carries. CONCLUSIONS These findings suggest that sensitive subpopulations defined by diet, hemoglobin level, and genotype may absorb more cadmium from their environment and thus should be considered in cadmium risk analyses. These findings are particularly relevant given the high prevalence of the H63D variant worldwide.
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Affiliation(s)
| | - Joel Schwartz
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
| | - David C Bellinger
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Neurology, Children's Hospital Boston, Boston, MA, USA.
| | - Russ Hauser
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
| | - Chitra Amarasiriwardena
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - David Sparrow
- VA Normative Aging Study, Veterans Affairs Boston Healthcare System and the Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
| | - Robert O Wright
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Rooney JPK, Woods NF, Martin MD, Woods JS. Genetic polymorphisms of GRIN2A and GRIN2B modify the neurobehavioral effects of low-level lead exposure in children. ENVIRONMENTAL RESEARCH 2018; 165:1-10. [PMID: 29655037 PMCID: PMC5999567 DOI: 10.1016/j.envres.2018.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 03/31/2018] [Accepted: 04/02/2018] [Indexed: 05/10/2023]
Abstract
Lead (Pb) is neurotoxic and children are highly susceptible to this effect, particularly within the context of continuous low-level Pb exposure. A current major challenge is identification of children who may be uniquely susceptible to Pb toxicity because of genetic predisposition. Learning and memory are among the neurobehavioral processes that are most notably affected by Pb exposure, and modification of N-methyl-D-aspartate receptors (NMDAR) that regulate these processes during development are postulated to underlie these adverse effects of Pb. We examined the hypothesis that polymorphic variants of genes encoding glutamate receptor, ionotropic, NMDAR subunits 2A and 2B, GRIN2A and GRIN2B, exacerbate the adverse effects of Pb exposure on these processes in children. Participants were subjects who participated as children in the Casa Pia Dental Amalgam Clinical Trial and for whom baseline blood Pb concentrations and annual neurobehavioral test results over the 7 year course of the clinical trial were available. Genotyping assays were performed for variants of GRIN2A (rs727605 and rs1070503) and GRIN2B (rs7301328 and rs1806201) on biological samples acquired from 330 of the original 507 trial participants. Regression modeling strategies were employed to evaluate the association between genotype status, Pb exposure, and neurobehavioral test outcomes. Numerous significant adverse interaction effects between variants of both GRIN2A and GRIN2B, individually and in combination, and Pb exposure were observed particularly among boys, preferentially within the domains of Learning & Memory and Executive Function. In contrast, very few interaction effects were observed among similarly genotyped girls with comparable Pb exposure. These findings support observations of an essential role of GRIN2A and GRIN2B on developmental processes underlying learning and memory as well as other neurological functions in children and demonstrate, further, modification of Pb effects on these processes by specific variants of both GRIN2A and GRIN2B genes. These observations highlight the importance of genetic factors in defining susceptibility to Pb neurotoxicity and may have important public health implications for future strategies aimed at protecting children and adolescents from potential health risks associated with low-level Pb exposure.
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Affiliation(s)
- James P K Rooney
- Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland.
| | - Nancy F Woods
- Department of Biobehavioral Nursing and Health Informatics, University of Washington, Seattle, WA, USA
| | - Michael D Martin
- Departments of Oral Medicine and Epidemiology, University of Washington, Seattle, WA, USA
| | - James S Woods
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
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Mitra P, Sharma S, Purohit P, Sharma P. Clinical and molecular aspects of lead toxicity: An update. Crit Rev Clin Lab Sci 2017; 54:506-528. [DOI: 10.1080/10408363.2017.1408562] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Prasenjit Mitra
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Shailja Sharma
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Purvi Purohit
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Praveen Sharma
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
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Park HR, Oh R, Wagner P, Panganiban R, Lu Q. New Insights Into Cellular Stress Responses to Environmental Metal Toxicants. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 331:55-82. [PMID: 28325215 DOI: 10.1016/bs.ircmb.2016.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Exposures to metal toxicants in the environment disrupt normal physiological functions and have been linked to the development of a myriad of human diseases. While the molecular and cellular mechanisms underlying metal toxicities remain to be fully understood, it is well appreciated that metal toxicants induce cellular stresses and that how cells respond to the stresses plays an important role in metal toxicity. In this review, we focus on how metal exposures induce stresses in the endoplasmic reticulum (ER) to elicit the unfolded protein response (UPR). We document the emerging evidence that induction of ER stress and UPR in the development of human diseases is associated with metal exposures. We also discuss the role of the interplay between ER stress and oxidative stress in metal toxicity. Finally, we review recent advances in functional genomics approaches and discuss how applications of these new tools could help elucidate the molecular mechanisms underlying cellular stresses induced by environmental metal toxicants.
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Affiliation(s)
- H-R Park
- Program in Molecular and Integrative Physiological Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - R Oh
- Program in Molecular and Integrative Physiological Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - P Wagner
- Program in Molecular and Integrative Physiological Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - R Panganiban
- Program in Molecular and Integrative Physiological Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Q Lu
- Program in Molecular and Integrative Physiological Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, United States.
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Prada D, Colicino E, Power MC, Weisskopf MG, Zhong J, Hou L, Spiro A, Vokonas P, Brenan K, Herrera LA, Schwartz J, Wright R, Hu H, Baccarelli AA. APOE ε4 allele modifies the association of lead exposure with age-related cognitive decline in older individuals. ENVIRONMENTAL RESEARCH 2016; 151:101-105. [PMID: 27474937 PMCID: PMC5071136 DOI: 10.1016/j.envres.2016.07.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/01/2016] [Accepted: 07/22/2016] [Indexed: 05/16/2023]
Abstract
BACKGROUND Continuing chronic and sporadic high-level of lead exposure in some regions in the U.S. has directed public attention to the effects of lead on human health. Long-term lead exposure has been associated with faster cognitive decline in older individuals; however, genetic susceptibility to lead-related cognitive decline during aging has been poorly studied. METHODS We determined the interaction of APOE-epsilon variants and environmental lead exposure in relation to age-related cognitive decline. We measured tibia bone lead by K-shell-x-ray fluorescence, APOE-epsilon variants by multiplex PCR and global cognitive z-scores in 489 men from the VA-Normative Aging Study. To determine global cognitive z-scores we incorporated multiple cognitive assessments, including word list memory task, digit span backwards, verbal fluency test, sum of drawings, and pattern comparison task, which were assessed at multiple visits. We used linear mixed-effect models with random intercepts for individual and for cognitive test. RESULTS An interquartile range (IQR:14.23μg/g) increase in tibia lead concentration was associated with a 0.06 (95% confidence interval [95%CI]: -0.11 to -0.01) lower global cognition z-score. In the presence of both ε4 alleles, one IQR increase in tibia lead was associated with 0.57 (95%CI: -0.97 to -0.16; p-value for interaction: 0.03) lower total cognition z-score. A borderline association was observed in presence of one ε4 allele (Estimate-effect per 1-IQR increase: -0.11, 95%CI: -0.22, 0.01) as well as lack of association in individuals without APOE ε4 allele. CONCLUSIONS Our findings suggest that individuals carrying both ε4 alleles are more susceptible to lead impact on global cognitive decline during aging.
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Affiliation(s)
- Diddier Prada
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA; Unidad de Investigación Biomédica en Cáncer, Instituto Nacional de Cancerología - Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City 14080, Mexico
| | - Elena Colicino
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Melinda C Power
- Department of Epidemiology and Biostatistics, George Washington University Milken Institute of Public Health, 950 New Hampshire Avenue NW, Washington, DC 20052, USA
| | - Marc G Weisskopf
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Jia Zhong
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Lifang Hou
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, 420 East Superior St, Chicago, IL 60611, USA
| | - Avron Spiro
- Veterans Affairs Boston Healthcare System, 150 South Huntington Ave, Boston, MA 02130, USA; Department of Epidemiology, Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, USA; Department of Psychiatry, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA
| | - Pantel Vokonas
- Veterans Affairs Boston Healthcare System, 150 South Huntington Ave, Boston, MA 02130, USA; Department of Epidemiology, Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, USA
| | - Kasey Brenan
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Luis A Herrera
- Unidad de Investigación Biomédica en Cáncer, Instituto Nacional de Cancerología - Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City 14080, Mexico
| | - Joel Schwartz
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | | | | | - Andrea A Baccarelli
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA.
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Nigg JT, Elmore AL, Natarajan N, Friderici KH, Nikolas MA. Variation in an Iron Metabolism Gene Moderates the Association Between Blood Lead Levels and Attention-Deficit/Hyperactivity Disorder in Children. Psychol Sci 2015; 27:257-69. [PMID: 26710823 DOI: 10.1177/0956797615618365] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 10/29/2015] [Indexed: 12/12/2022] Open
Abstract
Although attention-deficit/hyperactivity disorder (ADHD) is a heritable neurodevelopmental condition, there is also considerable scientific and public interest in environmental modulators of its etiology. Exposure to neurotoxins is one potential source of perturbation of neural, and hence psychological, development. Exposure to lead in particular has been widely investigated and is correlated with neurodevelopmental outcomes, including ADHD. To investigate whether this effect is likely to be causal, we used a Mendelian randomization design with a functional gene variant. In a case-control study, we examined the association between ADHD symptoms in children and blood lead level as moderated by variants in the hemochromatosis (HFE) gene. The HFE gene regulates iron uptake and secondarily modulates lead metabolism. Statistical moderation was observed: The magnitude of the association of blood lead with symptoms of ADHD was altered by functional HFE genotype, which is consistent with a causal hypothesis.
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Affiliation(s)
- Joel T Nigg
- Department of Psychiatry, Oregon Health & Science University Department of Behavioral Neuroscience, Oregon Health & Science University
| | - Alexis L Elmore
- Department of Psychological & Brain Sciences, University of Iowa
| | - Neil Natarajan
- Department of Psychiatry, Oregon Health & Science University
| | - Karen H Friderici
- Department of Microbiology and Molecular Genetics, Michigan State University
| | - Molly A Nikolas
- Department of Microbiology and Molecular Genetics, Michigan State University
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Kayaalti Z, Kaya-Akyüzlü D, Söylemez E, Söylemezoğlu T. Maternal hemochromatosis gene H63D single-nucleotide polymorphism and lead levels of placental tissue, maternal and umbilical cord blood. ENVIRONMENTAL RESEARCH 2015; 140:456-461. [PMID: 25981872 DOI: 10.1016/j.envres.2015.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 06/04/2023]
Abstract
Human hemochromatosis protein (HFE), a major histocompatibility complex class I-like integral membrane protein, participates in the down regulation of intestinal iron absorption by binding to transferrin receptor (TR). HFE competes with transferrin-bound iron for the TR and thus reduces uptake of iron into cells. On the other hand, a lack of HFE increases the intestinal absorption of iron similarly to iron deficiency associated with increasing in absorption and deposition of lead. During pregnancy, placenta cannot prevent transfer lead to the fetus; even low-level lead poisoning causes neurodevelopmental toxicity in children. The aim of this study was to determine the association between the maternal HFE H63D single-nucleotide polymorphism and lead levels in placental tissue, maternal blood and umbilical cord bloods. The study population comprised 93 mother-placenta pairs. Venous blood from mother was collected to investigate lead levels and HFE polymorphism that was detected by standard PCR-RFLP technique. Cord bloods and placentas were collected for lead levels which were analyzed by dual atomic absorption spectrometer system. The HFE H63D genotype frequencies of mothers were found as 75.3% homozygote typical (HH), 23.6% heterozygote (HD) and 1.1% homozygote atypical (DD). Our study results showed that the placental tissue, umbilical cord and maternal blood lead levels of mothers with HD+DD genotypes were significantly higher than those with HH genotype (p<0.05). The present study indicated for the first time that mothers with H63D gene variants have higher lead levels of their newborn's placentas and umbilical cord bloods.
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Affiliation(s)
- Zeliha Kayaalti
- Ankara University, Institute of Forensic Sciences, Ankara, Turkey.
| | | | - Esma Söylemez
- Ankara University, Institute of Forensic Sciences, Ankara, Turkey; Middle Black Sea Passage Generation of Agricultural Research Station Director, Tokat, Turkey
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Grashow R, Sparrow D, Hu H, Weisskopf MG. Cumulative lead exposure is associated with reduced olfactory recognition performance in elderly men: The Normative Aging Study. Neurotoxicology 2015; 49:158-64. [PMID: 26121922 DOI: 10.1016/j.neuro.2015.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 06/05/2015] [Accepted: 06/23/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Olfactory dysfunction has been identified as an early warning sign for Alzheimer's disease, Parkinson's disease, dementia and more. A few occupational and environmental exposures have also been associated with reduced olfactory function, although the effects of long term environmental exposure to lead on olfactory dysfunction have not been explored. Here we performed olfactory recognition testing in elderly men in a community-dwelling cohort and examined the association with cumulative lead exposure, as assessed by lead in tibial and patellar bone. METHODS Olfactory recognition was measured in 165 men from the Normative Aging Study (NAS) who had previously taken part in bone lead measurements using K-X-ray fluorescence (KXRF). Olfactory recognition was measured using the University of Pennsylvania Smell Identification Test (UPSIT). Associations between olfactory recognition, global cognition and cumulative lead exposure were estimated using linear regression, with additional adjustment for age, smoking, and functional polymorphism status for hemochromatosis (HFE), transferrin (TfC2), glutathione-s-transferase Pi1 (GSTP1) and apolipoprotein E (APOE) genotypes. Sensitivity analyses explored olfactory recognition in men with high global cognitive function as measured using the Mini-Mental Status Exam (MMSE). RESULTS The average age of the NAS participants at the time of olfactory recognition testing was 80.3 (standard deviation or SD=5.7) years. Mean tibia lead was 16.3 (SD=12.0) μg/g bone, mean patella lead was 22.4 (SD=14.4)μg/g bone, and mean UPSIT score was 26.9 out of 40 (SD=7.0). Consistent with previous findings, age at olfaction testing was negatively associated with UPSIT score. Tibia (but not patella) bone lead was negatively associated with olfaction recognition (per 15 μg/g tibia lead: β=-1.57; 95% CI: -2.93, -0.22; p=0.02) in models adjusted for smoking and age. Additional adjustment for education did not significantly change results. Of all the genes explored, only the presence of one or more HFE variant alleles was significantly associated with olfaction recognition (HFE β=2.26; 95% CI: 0.09, 4.43; p=0.04). In a model containing the HFE term and a lead term, the tibia lead parameter estimate dropped by 21% (per 15 μg/g tibia lead: β=-1.25; 95% CI: -2.64, 0.14; p=0.08) while the HFE term dropped 15% (β=1.91; 95% CI: -0.28, 4.10; p=0.09). None of the other gene terms were associated with olfactory recognition in this cohort, nor were any gene-lead interaction terms significant. Additional sensitivity analysis in men with MMSE scores of 25 or higher (n=149) showed a similar but slightly attenuated association between lead and olfactory recognition (per 15 μg/g tibia lead β=-1.39; 95% CI: -3.00, 0.22; p=0.09). CONCLUSION Cumulative exposure to lead is associated with reduced olfactory recognition in a cohort of elderly men. The association was similar but not significant in men with better cognitive function as measured by the MMSE. Iron metabolism gene status may also affect olfactory function.
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Affiliation(s)
- Rachel Grashow
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA.
| | - David Sparrow
- VA Boston Healthcare System, Boston University Schools of Public Health and Medicine, Boston, MA, USA; Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Howard Hu
- Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
| | - Marc G Weisskopf
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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von Stackelberg K, Guzy E, Chu T, Henn BC. Exposure to Mixtures of Metals and Neurodevelopmental Outcomes: A Multidisciplinary Review Using an Adverse Outcome Pathway Framework. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2015; 35:971-1016. [PMID: 26096925 PMCID: PMC5108657 DOI: 10.1111/risa.12425] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Current risk assessment guidance calls for an individual chemical-by-chemical approach that fails to capture potential interactive effects of exposure to environmental mixtures and genetic variability. We conducted a review of the literature on relationships between prenatal and early life exposure to mixtures of lead (Pb), arsenic (As), cadmium (Cd), and manganese (Mn) with neurodevelopmental outcomes. We then used an adverse outcome pathway (AOP) framework to integrate lines of evidence from multiple disciplines based on evolving guidance developed by the Organization for Economic Cooperation and Development (OECD). Toxicological evidence suggests a greater than additive effect of combined exposures to As-Pb-Cd and to Mn with any other metal, and several epidemiologic studies also suggest synergistic effects from binary combinations of Pb-As, Pb-Cd, and Pb-Mn. The exposure levels reported in these epidemiologic studies largely fall at the high-end (e.g., 95th percentile) of biomonitoring data from the National Health and Nutrition Examination Survey (NHANES), suggesting a small but significant potential for high-end exposures. This review integrates multiple data sources using an AOP framework and provides an initial application of the OECD guidance in the context of potential neurodevelopmental toxicity of several metals, recognizing the evolving nature of regulatory interpretation and acceptance.
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Affiliation(s)
- Katherine von Stackelberg
- Harvard Center for Risk Analysis, Boston, MA 02215;
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02215
| | - Elizabeth Guzy
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02215
| | - Tian Chu
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02215
| | - Birgit Claus Henn
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02215
- Now at the Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118
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The relationship between selected VDR, HFE and ALAD gene polymorphisms and several basic toxicological parameters among persons occupationally exposed to lead. Toxicology 2015; 334:12-21. [PMID: 25963508 DOI: 10.1016/j.tox.2015.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/04/2015] [Accepted: 05/06/2015] [Indexed: 02/06/2023]
Abstract
UNLABELLED The aim of this study was to find a relationship between polymorphisms of ALAD rs1805313, rs222808, rs1139488, VDR FokI and HFE C282Y and H63D and basic toxicological parameters (lead and ZnPP blood concentration) in people occupationally exposed to lead. We collected data of 101 workers (age 25-63 years) directly exposed to lead. The toxicological lab tests included blood lead, cadmium and ZnPP concentration measurement and arsenic urine concentration measurement. Workers were genotyped for ALAD (rs1805313, rs222808, rs1139488), HFE (C282Y, H63D) and VDR (FokI). Individuals with the lead exposure and coexisting F allel in the locus Fok-I of VDR gene are suspected of higher zinc protoporphyrins concentrations. Workers exposed to the lead with the Y allel in the locus C282Y of the HFE gene are predisposed to lower ZnPP levels and individuals with coexisting H allel in the locus H63D HFE gene are predisposed to lower Pb-B levels. The T allel in the locus rs1805313 of the ALAD gene determines lower Pb-B and ZnPP levels in lead-exposed individuals. The heterozigosity of the locus rs2228083 of the ALAD gene has a strong predilection to higher Pb-B levels. The carriage of the C allel in the locus rs1139488 of the ALAD gene might determine higher Pb-B levels and the heterozigosity of the locus rs1139488 of the ALAD gene might result in higher ZnPP levels. CONCLUSION The study revealed relationship between VDR, HFE and ALAD genes polymorphism and basic toxicological parameters in occupationally exposed workers.
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Karwowski MP, Just AC, Bellinger DC, Jim R, Hatley EL, Ettinger AS, Hu H, Wright RO. Maternal iron metabolism gene variants modify umbilical cord blood lead levels by gene-environment interaction: a birth cohort study. Environ Health 2014; 13:77. [PMID: 25287020 PMCID: PMC4271345 DOI: 10.1186/1476-069x-13-77] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 09/26/2014] [Indexed: 05/06/2023]
Abstract
BACKGROUND Given the relationship between iron metabolism and lead toxicokinetics, we hypothesized that polymorphisms in iron metabolism genes might modify maternal-fetal lead transfer. The objective of this study was to determine whether maternal and/or infant transferrin (TF) and hemochromatosis (HFE) gene missense variants modify the association between maternal blood lead (MBL) and umbilical cord blood lead (UCBL). METHODS We studied 476 mother-infant pairs whose archived blood specimens were genotyped for TF P570S, HFE H63D and HFE C282Y. MBL and UCBL were collected within 12 hours of delivery. Linear regression models were used to examine the association between log-transformed MBL and UCBL, examine for confounding and collinearity, and explore gene-environment interactions. RESULTS The geometric mean MBL was 0.61 μg/dL (range 0.03, 3.2) and UCBL 0.42 (<0.02, 3.9). Gene variants were common with carrier frequencies ranging from 12-31%; all were in Hardy-Weinberg equilibrium. In an adjusted linear regression model, log MBL was associated with log UCBL (β = 0.92, 95% CI: 0.82, 1.03; p < 0.01) such that a 1% increase in MBL was associated with a 0.92% increase in UCBL among infants born to wild-type mothers. In infants born to C282Y variants, however, a 1% increase in MBL is predicted to increase UCBL 0.65% (β(Main Effect) = -0.002, 95% CI: -0.09, -0.09; p = 0.97; β(Interaction) = -0.27, 95% CI: -0.52, -0.01; p = 0.04), representing a 35% lower placental lead transfer among women with MBL 5 μg/dL. CONCLUSIONS Maternal HFE C282Y gene variant status is associated with greater reductions in placental transfer of lead as MBL increases. The inclusion of gene-environment interaction in risk assessment models may improve efforts to safeguard vulnerable populations.
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Affiliation(s)
- Mateusz P Karwowski
- />Division of General Pediatrics, Pediatric Environmental Health Center, Boston Children’s Hospital, Boston, MA USA
- />Department of Environmental Health, Harvard School of Public Health, Boston, MA USA
| | - Allan C Just
- />Department of Environmental Health, Harvard School of Public Health, Boston, MA USA
| | - David C Bellinger
- />Department of Environmental Health, Harvard School of Public Health, Boston, MA USA
- />Department of Neurology, Boston Children’s Hospital, Boston, MA USA
| | - Rebecca Jim
- />Local Environmental Action Demanded Agency, Inc, Miami, OK USA
| | - Earl L Hatley
- />Local Environmental Action Demanded Agency, Inc, Miami, OK USA
| | - Adrienne S Ettinger
- />Department of Chronic Disease Epidemiology, Center for Perinatal, Pediatric, and Environmental Epidemiology, Yale School of Public Health, New Haven, CT USA
| | - Howard Hu
- />Divisions of Clinical Public Health, Epidemiology, Global Health, and Occupational and Environmental Health, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario Canada
| | - Robert O Wright
- />Departments of Preventive Medicine and Pediatrics, Icahn School of Medicine at Mt. Sinai, New York, NY USA
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Changing blood lead levels and oxidative stress with duration of residence among Taiwan immigrants. J Immigr Minor Health 2014; 15:1048-56. [PMID: 23558972 DOI: 10.1007/s10903-013-9820-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Immigrants lack appropriate health care access and other resources needed to reduce their exposure to preventable environmental health risks. Little is known about the impact of lead exposure and oxidative stress among immigrants. Thus, this study was to examine the differences between the blood lead levels (BLLs) and oxidative stress levels of immigrants and non-immigrants, and to investigate the determinants of increased BLLs or oxidative stress levels among immigrants. We collected demographic data of 239 immigrant women and 189 non-immigrant women who resettled in the central area of Taiwan. Each study participant provided blood samples for genotyping and for measuring blood metal levels and oxidative stress. Recent immigrants were at risk for elevated BLLs. Decreased BLLs, malondialdehyde (MDA), and increased blood selenium levels were significantly associated with duration of residence in Taiwan. Elevated BLLs and MDA in recent immigrants may serve as a warning sign for the health care system. The nation's health will benefit from improved regulation of living environments, thereby improving the health of immigrants.
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Kim J, Lee Y, Yang M. Environmental exposure to lead (Pb) and variations in its susceptibility. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2014; 32:159-85. [PMID: 24875442 DOI: 10.1080/10590501.2014.907461] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Based on exposure frequency and intrinsic toxicity, lead (Pb) ranks one of the highest priority toxic materials. Continuous regulation of environmental Pb exposure has contributed to dramatically diminished exposure levels of Pb, for example, blood level of Pb. However, the safety level of Pb is not established, as low-level exposure to Pb still shows severe toxicity in high susceptible population and late onset of some diseases from early exposure. In the present study, we focused on food-borne Pb exposure and found broad variations in Pb exposure levels via food among countries. In addition, there are genetic or ethnical variations in Pb-targeted and protective genes. Moreover, various epigenetic alterations were induced by Pb poisoning. Therefore, we suggest a systemic approach including governmental (public) and individual prevention from Pb exposure with continuous biological monitoring and genetic or epigenetic consideration.
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Affiliation(s)
- Jina Kim
- a Research Center for Cell Fate Control, College of Pharmacy , Sookmyung Women's University , Seoul , Republic of Korea
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Modifying roles of glutathione S-transferase polymorphisms on the association between cumulative lead exposure and cognitive function. Neurotoxicology 2013; 39:65-71. [PMID: 23958642 DOI: 10.1016/j.neuro.2013.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/05/2013] [Accepted: 08/06/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND Glutathione-S-transferase gene (GST) polymorphisms can result in variable ability of these enzymes to remove electrophilic substrates. We investigated whether the GSTP1 Val105 and GSTM1 deletion polymorphisms modify the lead-cognitive function association. METHODS We used repeated measures analysis to compare the association between cumulative lead biomarkers-bone lead measured using K-shell X-Ray Fluorescence-and Mini-Mental State Exam (MMSE) score by GST variants, adjusted for covariates, among Normative Aging Study participants, a Boston-based prospective cohort of men. We had complete data for 698 men (providing 1292 observations) for GSTM1 analyses and 595 men (providing 1142 observations) for GSTP1 analyses. RESULTS A 15μg/g higher tibia lead concentration (interquartile range of tibia lead) was associated with a 0.24 point decrement in MMSE score among GSTP1 Val105 variant carriers, which was significantly stronger than the association among men with only wild-type alleles (p=0.01). The association among GSTP1 Val105 carriers was comparable to that of 3 years of age in baseline MMSE scores. The association between tibia lead and MMSE score appeared progressively steeper in participants with increasingly more GSTP1 Val105 alleles. A modest association between tibia lead and lower MMSE score was seen among participants with the GSTM1 deletion polymorphism. Neither of the glutathione S-transferase variants was independently associated with cognitive function, nor with lead biomarker measures. The results pertaining to patella lead were similar to those observed for tibia lead. CONCLUSION Our results suggest that the GSTP1 Val105 polymorphism confers excess susceptibility to the cognitive effects of cumulative lead exposure.
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Roy A, Ettinger AS, Hu H, Bellinger D, Schwartz J, Modali R, Wright RO, Palaniappan K, Balakrishnan K. Effect modification by transferrin C2 polymorphism on lead exposure, hemoglobin levels, and IQ. Neurotoxicology 2013; 38:17-22. [PMID: 23732512 DOI: 10.1016/j.neuro.2013.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/07/2013] [Accepted: 05/09/2013] [Indexed: 01/31/2023]
Abstract
BACKGROUND Iron deficiency and lead exposure remain significant public health issues in many parts of the world and are both independently associated with neurocognitive deficits. Polymorphisms in iron transport pathways have been shown to modify the absorption and toxicity of lead. OBJECTIVE We hypothesized that the transferrin (TF) C2 polymorphism modifies the effects of lead and hemoglobin on intelligence. METHODS Children aged 3-7 years (N=708) were enrolled from 12 primary schools in Chennai, India. The Binet-Kamath Scale of Intelligence were administered to ascertain intelligence quotient (IQ). Venous blood was analyzed for lead and hemoglobin levels. Genotyping for the TF C2 polymorphism (rs1049296) was carried out using a MassARRAY iPLEXTM platform. Stratified analyses and interaction models, using generalized estimating equations, were examined to explore interactions between lead, hemoglobin, and TF C2 categories. RESULTS A one-unit increase in log blood lead and 1g/dl higher hemoglobin was associated with -77 (95% CI: -136, -18) and 17 (95% CI 14, 21) IQ points, respectively, among children carrying the C2 variant. In comparison, among children who had the homozygous wildtype allele, the same increment of lead and hemoglobin were associated with -21(95% CI: -65, 24) and 28 (95% CI: 15, 40) IQ points, respectively. There was a significant interaction between lead (p=0.04) and hemoglobin (p=0.07) with the C2 variant. CONCLUSION Children who carry the TF C2 variant may be more susceptible to the neurotoxic effects of lead exposure and less protected by higher levels of hemoglobin.
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Affiliation(s)
- Ananya Roy
- Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, CT, United States.
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Alfred T, Ben-Shlomo Y, Cooper R, Hardy R, Deary IJ, Elliott J, Harris SE, Hyppönen E, Kivimaki M, Kumari M, Maddock J, Power C, Starr JM, Kuh D, Day IN. Genetic variants influencing biomarkers of nutrition are not associated with cognitive capability in middle-aged and older adults. J Nutr 2013; 143:606-12. [PMID: 23468552 PMCID: PMC3738233 DOI: 10.3945/jn.112.171520] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Several investigations have observed positive associations between good nutritional status, as indicated by micronutrients, and cognitive measures; however, these associations may not be causal. Genetic polymorphisms that affect nutritional biomarkers may be useful for providing evidence for associations between micronutrients and cognitive measures. As part of the Healthy Ageing across the Life Course (HALCyon) program, men and women aged between 44 and 90 y from 6 UK cohorts were genotyped for polymorphisms associated with circulating concentrations of iron [rs4820268 transmembrane protease, serine 6 (TMPRSS6) and rs1800562 hemochromatosis (HFE)], vitamin B-12 [(rs492602 fucosyltransferase 2 (FUT2)], vitamin D ([rs2282679 group-specific component (GC)] and β-carotene ([rs6564851 beta-carotene 15,15'-monooxygenase 1 (BCMO1)]. Meta-analysis was used to pool within-study effects of the associations between these polymorphisms and the following measures of cognitive capability: word recall, phonemic fluency, semantic fluency, and search speed. Among the several statistical tests conducted, we found little evidence for associations. We found the minor allele of rs1800562 was associated with poorer word recall scores [pooled β on Z-score for carriers vs. noncarriers: -0.05 (95% CI: -0.09, -0.004); P = 0.03, n = 14,105] and poorer word recall scores for the vitamin D-raising allele of rs2282679 [pooled β per T allele: -0.03 (95% CI: -0.05, -0.003); P = 0.03, n = 16,527]. However, there was no evidence for other associations. Our findings provide little evidence to support associations between these genotypes and cognitive capability in older adults. Further investigations are required to elucidate whether the previous positive associations from observational studies between circulating measures of these micronutrients and cognitive performance are due to confounding and reverse causality.
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Affiliation(s)
- Tamuno Alfred
- School of Social and Community Medicine, University of Bristol, Bristol, UK.
| | - Yoav Ben-Shlomo
- School of Social and Community Medicine, University of Bristol, Bristol, UK
| | - Rachel Cooper
- MRC Unit for Lifelong Health and Ageing and Division of Population Health, University College London, London, UK
| | - Rebecca Hardy
- MRC Unit for Lifelong Health and Ageing and Division of Population Health, University College London, London, UK
| | - Ian J. Deary
- Centre for Cognitive Ageing and Cognitive Epidemiology, and,Department of Psychology, University of Edinburgh, Edinburgh, UK
| | - Jane Elliott
- Centre for Longitudinal Studies, Department of Quantitative Social Sciences, Institute of Education, London, UK
| | - Sarah E. Harris
- Centre for Cognitive Ageing and Cognitive Epidemiology, and,Medical Genetics Section, University of Edinburgh, Edinburgh, UK
| | - Elina Hyppönen
- MRC Centre of Epidemiology for Child Health/Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, London, UK
| | - Mika Kivimaki
- Department of Epidemiology and Public Health, University College London, London, UK
| | - Meena Kumari
- Department of Epidemiology and Public Health, University College London, London, UK
| | - Jane Maddock
- MRC Centre of Epidemiology for Child Health/Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, London, UK
| | - Chris Power
- MRC Centre of Epidemiology for Child Health/Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, London, UK
| | - John M. Starr
- Centre for Cognitive Ageing and Cognitive Epidemiology, and,Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK; and
| | - Diana Kuh
- MRC Unit for Lifelong Health and Ageing and Division of Population Health, University College London, London, UK
| | - Ian N.M. Day
- School of Social and Community Medicine, University of Bristol, Bristol, UK,MRC Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK
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Bakulski KM, Rozek LS, Dolinoy DC, Paulson HL, Hu H. Alzheimer's disease and environmental exposure to lead: the epidemiologic evidence and potential role of epigenetics. Curr Alzheimer Res 2012; 9:563-73. [PMID: 22272628 PMCID: PMC3567843 DOI: 10.2174/156720512800617991] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 10/20/2011] [Accepted: 01/20/2012] [Indexed: 11/22/2022]
Abstract
Several lines of evidence indicate that the etiology of late-onset Alzheimer's disease (LOAD) is complex, with significant contributions from both genes and environmental factors. Recent research suggests the importance of epigenetic mechanisms in defining the relationship between environmental exposures and LOAD. In epidemiologic studies of adults, cumulative lifetime lead (Pb) exposure has been associated with accelerated declines in cognition. In addition, research in animal models suggests a causal association between Pb exposure during early life, epigenetics, and LOAD. There are multiple challenges to human epidemiologic research evaluating the relationship between epigenetics, LOAD, and Pb exposure. Epidemiologic studies are not well-suited to accommodate the long latency period between exposures during early life and onset of Alzheimer's disease. There is also a lack of validated circulating epigenetics biomarkers and retrospective biomarkers of Pb exposure. Members of our research group have shown bone Pb is an accurate measurement of historical Pb exposure in adults, offering an avenue for future epidemiologic studies. However, this would not address the risk of LOAD attributable to early-life Pb exposures. Future studies that use a cohort design to measure both Pb exposure and validated epigenetic biomarkers of LOAD will be useful to clarify this important relationship.
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Affiliation(s)
- Kelly M. Bakulski
- University of Michigan, School of Public Health, Department of Environmental Health Sciences
| | - Laura S. Rozek
- University of Michigan, School of Public Health, Department of Environmental Health Sciences
- University of Michigan, Medical School, Department of Otolaryngology
| | - Dana C. Dolinoy
- University of Michigan, School of Public Health, Department of Environmental Health Sciences
| | | | - Howard Hu
- University of Michigan, School of Public Health, Department of Environmental Health Sciences
- University of Michigan, Department of Epidemiology
- University of Michigan, Medical School, Department of Internal Medicine
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20
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Loef M, Mendoza LF, Walach H. Lead (Pb) and the Risk of Alzheimer’s disease or cognitive decline: A systematic review. TOXIN REV 2011. [DOI: 10.3109/15569543.2011.624664] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Zhang A, Park SK, Wright RO, Weisskopf MG, Mukherjee B, Nie H, Sparrow D, Hu H. HFE H63D polymorphism as a modifier of the effect of cumulative lead exposure on pulse pressure: the Normative Aging Study. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:1261-6. [PMID: 20478760 PMCID: PMC2944087 DOI: 10.1289/ehp.1002251] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2010] [Accepted: 05/14/2010] [Indexed: 05/06/2023]
Abstract
BACKGROUND Cumulative lead exposure is associated with a widened pulse pressure (PP; the -difference between systolic and diastolic blood pressure), a marker of arterial stiffness and a predictor of cardiovascular disease. Polymorphisms in the hemochromatosis gene (HFE) have been shown to modify the impact of cumulative lead exposure on measures of adult cognition and cardiac function. OBJECTIVES We examined whether the HFE mutations modify the impact of lead on PP in -community-dwelling older men. METHODS We examined 619 participants with a total of 1,148 observations of PP from a substudy of bone lead levels (a measure of cumulative exposure, measured by in vivo K-shell X-ray fluorescence) and health in the Normative Aging Study between 1991 and 2001. Linear mixed-effects regression models with random intercepts were constructed. RESULTS Of the 619 subjects, 138 and 72 carried the HFE H63D and C282Y variants, respectively. After adjusting for age; education; alcohol intake; smoking; daily intakes of calcium, sodium, and potassium; total calories; family history of hypertension; diabetes; height; heart rate; high-density lipoprotein (HDL); total cholesterol:HDL ratio; and waist circumference, baseline bone lead levels were associated with steeper increases in PP in men with at least one H63D allele (p-interaction = 0.03 for tibia and 0.02 for patella) compared with men with only the wild types or C282Y variant. CONCLUSIONS The HFE H63D polymorphism, but not the C282Y mutation, appears to enhance susceptibility to the deleterious impact of cumulative lead on PP, possibly via prooxidative or pro-inflammatory mechanisms.
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Affiliation(s)
- Aimin Zhang
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
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Cantonwine D, Hu H, Téllez-Rojo MM, Sánchez BN, Lamadrid-Figueroa H, Ettinger AS, Mercado-García A, Hernández-Avila M, Wright RO. HFE gene variants modify the association between maternal lead burden and infant birthweight: a prospective birth cohort study in Mexico City, Mexico. Environ Health 2010; 9:43. [PMID: 20659343 PMCID: PMC2916893 DOI: 10.1186/1476-069x-9-43] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 07/26/2010] [Indexed: 05/11/2023]
Abstract
BACKGROUND Neonatal growth is a complex process involving genetic and environmental factors. Polymorphisms in the hemochromatosis (HFE) iron regulatory genes have been shown to modify transport and toxicity of lead which is known to affect birth weight. METHODS We investigated the role of HFE C282Y, HFE H63 D, and transferrin (TF) P570 S gene variants in modifying the association of lead and infant birthweight in a cohort of Mexican mother-infant pairs. Subjects were initially recruited between 1994-1995 from three maternity hospitals in Mexico City and 411 infants/565 mothers had archived blood available for genotyping. Multiple linear regression models, stratified by either maternal/infant HFE or TF genotype and then combined with interaction terms, were constructed examining the association of lead and birthweight after controlling for covariates. RESULTS 3.1%, 16.8% and 17.5% of infants (N=390) and 1.9%, 14.5% and 18.9% of mothers (N=533) carried the HFE C282Y, HFE H63D, and TF P570 S variants, respectively. The presence of infant HFE H63 D variants predicted 110.3 g (95% CI -216.1, -4.6) decreases in birthweight while maternal HFE H63 D variants predicted reductions of 52.0 g (95% CI -147.3 to 43.2). Interaction models suggest that both maternal and infant HFE H63 D genotype may modify tibia lead's effect on infant birthweight in opposing ways. In our interaction models, maternal HFE H63 D variant carriers had a negative association between tibia lead and birthweight. CONCLUSIONS These results suggest that the HFE H63 D genotype modifies lead's effects on infant birthweight in a complex fashion that may reflect maternal-fetal interactions with respect to the metabolism and transport of metals.
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Affiliation(s)
- David Cantonwine
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Howard Hu
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Martha Maria Téllez-Rojo
- Division of Statistics, Center for Evaluation Research and Surveys, National Institute of Public Health, Cuernavaca, Morelos, México
| | - Brisa N Sánchez
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Héctor Lamadrid-Figueroa
- Division of Statistics, Center for Evaluation Research and Surveys, National Institute of Public Health, Cuernavaca, Morelos, México
| | - Adrienne S Ettinger
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Adriana Mercado-García
- Division of Environmental Health, Center for Population Health Research, National Institute of Public Health, Cuernavaca, Morelos, México
| | | | - Robert O Wright
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Gundacker C, Gencik M, Hengstschläger M. The relevance of the individual genetic background for the toxicokinetics of two significant neurodevelopmental toxicants: mercury and lead. Mutat Res 2010; 705:130-140. [PMID: 20601101 DOI: 10.1016/j.mrrev.2010.06.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/07/2010] [Accepted: 06/10/2010] [Indexed: 11/25/2022]
Abstract
The heavy metals mercury and lead are well-known and significant developmental neurotoxicants. This review summarizes the genetic factors that modify their toxicokinetics. Understanding toxicokinetics (uptake, biotransformation, distribution, and elimination processes) is a key precondition to understanding the individual health risks associated with exposure. We selected candidate susceptibility genes when evidence was available for (1) genes/proteins playing a significant role in mercury and lead toxicokinetics, (2) gene expression/protein activity being induced by these metals, and (3) mercury and lead toxicokinetics being affected by gene knockout/knockdown or (4) by functional gene polymorphisms. The genetic background is far better known for mercury than for lead toxicokinetics. Involved are genes encoding L-type amino acid transporters, organic anion transporters, glutathione (GSH)-related enzymes, metallothioneins, and transporters of the ABC family. Certain gene variants can influence mercury toxicokinetics, potentially explaining part of the variable susceptibility to mercury toxicity. Delta-aminolevulinic acid dehydratase (ALAD), vitamin D receptor (VDR) and hemochromatosis (HFE) gene variants are the only well-established susceptibility markers of lead toxicity in humans. Many gaps remain in our knowledge about the functional genomics of this issue. This calls for studies to detect functional gene polymorphisms related to mercury- and lead-associated disease phenotypes, to demonstrate the impact of functional polymorphisms and gene knockout/knockdown in relation to toxicity, to confirm the in vivo relevance of genetic variation, and to examine gene-gene interactions on the respective toxicokinetics. Another crucial aspect is knowledge on the maternal-fetal genetic background, which modulates fetal exposure to these neurotoxicants. To completely define the genetically susceptible risk groups, research is also needed on the genes/proteins involved in the toxicodynamics, i.e., in the mechanisms causing adverse effects in the brain. Studies relating the toxicogenetics to neurodevelopmental disorders are lacking (mercury) or very scarce (lead). Thus, the extent of variability in susceptibility to heavy metal-associated neurological outcomes is poorly characterized.
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Affiliation(s)
- Claudia Gundacker
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, A-1090 Vienna, Austria.
| | - Martin Gencik
- Praxis fur Humangenetik, Brünnlbadgasse 15, A-1090 Vienna, Austria
| | - Markus Hengstschläger
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, A-1090 Vienna, Austria
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Abstract
SummaryThis review discusses the role that the APOE gene plays in cognitive dysfunction both in demented and non-demented elderly people. The increasing problem of cognitive impairment in developed countries makes finding new and effective treatments a research priority. Understanding the biological basis of this impairment is therefore paramount. APOE has received much attention in the field of cognitive genetics due to it being a major susceptibility gene for Alzheimer's disease, which itself is characterized by a rapid and irreversible loss in memory function. Over the past 14 years this has generated a considerable number of publications that have produced conflicting findings, making it difficult for the reader to interpret whether the APOE gene regulates cognition or not. This review attempts to summarize the mass of information on this gene in relation to cognition, by weighting the pros and cons of the methodologies used, and offers suggestions for future study designs.
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Payton A. The Impact of Genetic Research on our Understanding of Normal Cognitive Ageing: 1995 to 2009. Neuropsychol Rev 2009; 19:451-77. [DOI: 10.1007/s11065-009-9116-z] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 08/17/2009] [Indexed: 12/11/2022]
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Gundacker C, Wittmann KJ, Kukuckova M, Komarnicki G, Hikkel I, Gencik M. Genetic background of lead and mercury metabolism in a group of medical students in Austria. ENVIRONMENTAL RESEARCH 2009; 109:786-796. [PMID: 19515364 DOI: 10.1016/j.envres.2009.05.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 05/14/2009] [Accepted: 05/19/2009] [Indexed: 05/27/2023]
Abstract
BACKGROUND Information on the impact of genetic predisposition on metal toxicokinetics in the human body is limited. There is increasing evidence that certain genetic polymorphisms modify lead and mercury toxicokinetics. This called for analysis of further candidate genes. OBJECTIVES Medical students (N=324) were examined in order to detect potential associations between lead exposure and polymorphisms in HFE, VDR, ALAD, and MT genes, as well as between mercury exposure and GSTT1, GSTM1, GSTA1, GSTP1, GCLC, and MT polymorphisms. METHODS The levels of lead and mercury exposure of students were determined by blood, urine, and hair analyses (ICP-MS, CV-AAS). Genotyping of common polymorphisms was examined by MALDI-TOF MS and the TaqMan methodology. Associations between lead and mercury exposures and genetic background were examined by bivariate analysis, and by categorical regression analysis (CATREG) controlled by metal- and matrix-specific variables. RESULTS Lead and mercury levels in urine, blood, and hair indicated low exposures. VDR polymorphism and joint presence of VDR/ALAD polymorphisms were significantly and independently associated with urine lead concentrations (CATREG P<0.05). Polymorphisms in GSTP1-114 and MT4 genes as well as dual gene combinations including GSTP1, GCLC, GSTT1, and GSTM1 polymorphisms were independent variables related to mercury body burdens (CATREG P<0.05). GSTP1-114/GSTT1 and GSTP1-105/GCLC combinations showed synergistic effects on hair mercury levels compared to single-gene variants. CONCLUSIONS We found evidence that certain genetic backgrounds were associated with lead and mercury metabolism, suggesting gene-environment and gene-gene-environment interactions. The modes of interaction remain to be evaluated.
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Affiliation(s)
- Claudia Gundacker
- Medical University of Vienna, Center for Public Health, Lab Ecotoxicology, Waehringer Strasse 10, A-1090 Vienna, Austria.
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Bellinger DC. Interpreting epidemiologic studies of developmental neurotoxicity: conceptual and analytic issues. Neurotoxicol Teratol 2009; 31:267-74. [PMID: 19595760 DOI: 10.1016/j.ntt.2009.06.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 06/20/2009] [Accepted: 06/25/2009] [Indexed: 11/25/2022]
Abstract
This paper discusses issues pertaining to the validity, precision, and interpretation of epidemiologic studies of neurotoxicity. With regard to validity, the critical issues pertain to the appropriate strategy for confounder adjustment, particularly when confounders are complex, multi-faceted constructs, and to the need for greater clarity and transparency in articulating the causal relationships implicit in the analytic approach applied. With regard to precision, the critical issue is a need to identify the contributors to the substantial variability observed in the effect estimates that describe dose-response and dose-effect relationships. In addition to methodological sources, such as imprecision in estimating dose at the critical organ site(s), true inter-individual differences in susceptibility to a neurotoxicant could also contribute to the variability. Variability might be reduced by taking full account of factors such as co-exposures or health co-morbidities, genetic polymorphisms, and the social ecology of exposure. With regard to interpretation, we need to do a better job as a field conveying to risk assessors and others the ecological significance of the types of performance deficits observed following neurotoxicant exposure, emphasizing the distinction between individual and population risk. A final issue discussed is the need to define standards for the conduct, analysis, and reporting of epidemiologic studies of neurotoxicity, similar to those developed for other fields.
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Affiliation(s)
- David C Bellinger
- Children's Hospital Boston, Harvard Medical School, Harvard School of Public Health, Farley Basement Box 127, Children's Hospital, Boston, MA 02115, USA.
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Park SK, Hu H, Wright RO, Schwartz J, Cheng Y, Sparrow D, Vokonas PS, Weisskopf MG. Iron metabolism genes, low-level lead exposure, and QT interval. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:80-5. [PMID: 19165391 PMCID: PMC2627870 DOI: 10.1289/ehp.11559] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 08/22/2008] [Indexed: 05/22/2023]
Abstract
BACKGROUND Cumulative exposure to lead has been shown to be associated with depression of electrocardiographic conduction, such as QT interval (time from start of the Q wave to end of the T wave). Because iron can enhance the oxidative effects of lead, we examined whether polymorphisms in iron metabolism genes [hemochromatosis (HFE), transferrin (TF) C2, and heme oxygenase-1 (HMOX-1)] increase susceptibility to the effects of lead on QT interval in 613 community-dwelling older men. METHODS We used standard 12-lead electrocardiograms, K-shell X-ray fluorescence, and graphite furnace atomic absorption spectrometry to measure QT interval, bone lead, and blood lead levels, respectively. RESULTS A one-interquartile-range increase in tibia lead level (13 mug/g) was associated with a 11.35-msec [95% confidence interval (CI), 4.05-18.65 msec] and a 6.81-msec (95% CI, 1.67-11.95 msec) increase in the heart-rate-corrected QT interval among persons carrying long HMOX-1 alleles and at least one copy of an HFE variant, respectively, but had no effect in persons with short and middle HMOX-1 alleles and the wild-type HFE genotype. The lengthening of the heart-rate-corrected QT interval with higher tibia lead and blood lead became more pronounced as the total number (0 vs. 1 vs. >/=2) of gene variants increased (tibia, p-trend = 0.01; blood, p-trend = 0.04). This synergy seems to be driven by a joint effect between HFE variant and HMOX-1 L alleles. CONCLUSION We found evidence that gene variants related to iron metabolism increase the impacts of low-level lead exposure on the prolonged QT interval. This is the first such report, so these results should be interpreted cautiously and need to be independently verified.
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Affiliation(s)
- Sung Kyun Park
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan 48109, USA.
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Bellinger DC. Late neurodevelopmental effects of early exposures to chemical contaminants: reducing uncertainty in epidemiological studies. Basic Clin Pharmacol Toxicol 2008; 102:237-44. [PMID: 18226079 DOI: 10.1111/j.1742-7843.2007.00164.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Early exposures to environmental chemicals are reliably associated with late neurotoxicities in children. However, substantial scatter of observations exists around the estimated dose-effect relationships. This variability has many potential sources, one of which is interindividual differences in susceptibility. Such differences imply that the long-term impacts of exposure will not the same for all individuals, but will vary depending on a variety of factors that might either aggravate or mitigate contaminant effects. These include co-exposures, genetic polymorphisms and characteristics of the social environment. The context dependence of contaminant effects has implications both for study designs and analytical approaches. In addition, a systems approach to understanding the associations among contaminant exposures, covariates and health outcomes is necessary.
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Affiliation(s)
- David C Bellinger
- Department of Neurology, Children's Hospital Boston, Boston, MA 02115, USA.
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