Prenatal exposures to persistent and non-persistent organic compounds and effects on immune system development

Parental occupational exposures and autism spectrum disorder

Both self-report and industrial hygienist (IH) assessed parental occupational information were used in this pilot study in which 174 families (93 children with ASD and 81 unaffected children) enrolled in the Childhood Autism Risks from Genetics and Environment study participated. IH results indicated exposures to lacquer, varnish, and xylene occurred more often in the parents of children with ASD compared to the parents of unaffected children. Parents of children with ASD were more likely to report exposures to asphalt and solvents compared to parents of unaffected children. This study was limited by the small sample size, but results suggest that workplace exposures to some chemicals may be important in the etiology of ASD and deserve further investigation.

Early-life environmental determinants of allergic diseases and the wider pandemic of inflammatory noncommunicable diseases

The unparalleled burden of a diverse range of chronic noncommunicable diseases (NCDs) is a major global challenge in the 21st century. Chronic low-grade inflammation is a common feature of virtually all NCDs, indicating a central role of the immune system. Furthermore, as the most common and earliest-onset NCD, the epidemic of allergic diseases points to specific vulnerability of the developing immune system to modern environmental change. Indeed, many environmental risk factors implicated in the rise of other NCDs have been shown to mediate their effects through immune pathways. The innate immune system provides a clear example of this convergence, with evidence that physical activity, nutrition, pollutants, and the microbiome all influence systemic inflammation through Toll-like receptor pathways (notably Toll-like receptor 4), with downstream effects on the risk of insulin resistance, obesity, cardiovascular risk, immune diseases, and even mood and behavior. Common risk factors will likely mean common solutions, and interdisciplinary strategies to promote immune health should be an integral part of NCD prevention, with a greater focus early in the life course before disease processes are established. In this context allergic disease provides a very important early target to assess the effectiveness of environmental strategies to reduce immune dysregulation.

Ambient air pollution and autism in Los Angeles county, California

BACKGROUND

The prevalence of autistic disorder (AD), a serious developmental condition, has risen dramatically over the past two decades, but high-quality population-based research addressing etiology is limited.

OBJECTIVES

We studied the influence of exposures to traffic-related air pollution during pregnancy on the development of autism using data from air monitoring stations and a land use regression (LUR) model to estimate exposures.

METHODS

Children of mothers who gave birth in Los Angeles, California, who were diagnosed with a primary AD diagnosis at 3-5 years of age during 1998-2009 were identified through the California Department of Developmental Services and linked to 1995-2006 California birth certificates. For 7,603 children with autism and 10 controls per case matched by sex, birth year, and minimum gestational age, birth addresses were mapped and linked to the nearest air monitoring station and a LUR model. We used conditional logistic regression, adjusting for maternal and perinatal characteristics including indicators of SES.

RESULTS

Per interquartile range (IQR) increase, we estimated a 12-15% relative increase in odds of autism for ozone [odds ratio (OR) = 1.12, 95% CI: 1.06, 1.19; per 11.54-ppb increase] and particulate matter ≤ 2.5 µm (OR = 1.15; 95% CI: 1.06, 1.24; per 4.68-μg/m3 increase) when mutually adjusting for both pollutants. Furthermore, we estimated 3-9% relative increases in odds per IQR increase for LUR-based nitric oxide and nitrogen dioxide exposure estimates. LUR-based associations were strongest for children of mothers with less than a high school education.

CONCLUSION

Measured and estimated exposures from ambient pollutant monitors and LUR model suggest associations between autism and prenatal air pollution exposure, mostly related to traffic sources.

Placental transfer of persistent organic pollutants: a preliminary study on mother-newborn pairs

The aim of this study was to characterize the placental transfer of some environmental pollutants, and to explore the possibility of quantitatively predicting in utero exposure to these contaminants from concentrations assessed in maternal blood. Levels of toxic substances such as pesticides (p,p'-DDE, β-HCH, and HCB), polychlorinated biphenyls (PCBs), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA) were determined in serum samples of 38 pregnant women living in Rome and in samples of cord blood from their respective newborns. The study was carried out in the years 2008-2009. PCB mean concentrations in maternal serum and cord serum ranged from 0.058 to 0.30, and from 0.018 to 0.064 ng/g · fw respectively. Arithmetic means of PFOS and PFOA concentrations in mothers and newborns were 3.2 and 1.4 ng/g · fw, and 2.9 and 1.6 ng/g · fw. A strong correlation was observed between concentrations in the maternal and the foetal compartment for PFOS (Spearman r = 0.74, p < 0.001), PFOA (Spearman r = 0.70, p < 0.001), PCB 153 (Spearman r = 0.60, p < 0.001), HCB (Spearman r = 0.68, p < 0.001), PCB 180 (Spearman r = 0.55, p = 0.0012), and p,p'-DDE (Spearman r = 0.53, p = 0.0099). A weak correlation (p < 0.1) was observed for PCBs 118 and 138.

The science of early life toxic stress for pediatric practice and advocacy

Young children who experience toxic stress are at high risk for a number of health outcomes in adulthood, including cardiovascular disease, cancers, asthma, and depression. The American Academy of Pediatrics has recently called on pediatricians, informed by research from molecular biology, genomics, immunology, and neuroscience, to become leaders in science-based strategies to build strong foundations for children's life-long health. In this report, we provide an overview of the science of toxic stress. We summarize the development of the neuroendocrine-immune network, how its function is altered by early life adversity, and how these alterations then increase vulnerability to disease. The fact that early environments shape and calibrate the functioning of biological systems very early in life is both a cautionary tale about overlooking critical periods in development and reason for optimism about the promise of intervention. Even in the most extreme cases of adversity, well-timed changes to children's environments can improve outcomes. Pediatricians are in a unique position to contribute to the public discourse on health and social welfare by explaining how factors that seem distal to child health may be the key to some of the most intractable public health problems of our generation. We consider the challenges and opportunities for preventing toxic stress in the context of contemporary pediatric practice.

Health impact of air pollution to children

Health impact of air pollution to children was studied over the last twenty years in heavily polluted parts of the Czech Republic during. The research program (Teplice Program) analyzed these effects in the polluted district Teplice (North Bohemia) and control district Prachatice (Southern Bohemia). Study of pregnancy outcomes for newborns delivered between 1994 and 1998 demonstrated that increase in intrauterine growth retardation (IUGR) was associated with PM10 and c-PAHs exposure (carcinogenic polycyclic aromatic hydrocarbons) in the first month of gestation. Morbidity was followed in the cohort of newborns (N=1492) up to the age of 10years. Coal combustion in homes was associated with increased incidence of lower respiratory track illness and impaired early childhood skeletal growth up to the age of 3years. In preschool children, we observed the effect of increased concentrations of PM2.5 and PAHs on development of bronchitis. The Northern Moravia Region (Silesia) is characterized by high concentrations of c-PAHs due to industrial air pollution. Exposure to B[a]P (benzo[a]pyrene) in Ostrava-Radvanice is the highest in the EU. Children from this part of the city of Ostrava suffered higher incidence of acute respiratory diseases in the first year of life. Gene expression profiles in leukocytes of asthmatic children compared to children without asthma were evaluated in groups from Ostrava-Radvanice and Prachatice. The results suggest the distinct molecular phenotype of asthma bronchiale in children living in polluted Ostrava region compared to children living in Prachatice. The effect of exposure to air pollution to biomarkers in newborns was analyzed in Prague vs. Ceske Budejovice, two locations with different levels of pollution in winter season. B[a]P concentrations were higher in Ceske Budejovice. DNA adducts and micronuclei were also elevated in cord blood in Ceske Budejovice in comparison to Prague. Study of gene expression profiles in the cord blood showed differential expression of 104 genes. Specifically, biological processes related to immune and defense response were down-regulated in Ceske Budejovice. Our studies demonstrate that air pollution significantly affect child health. Especially noticeable is the increase of respiratory morbidity. With the development of molecular epidemiology, we can further evaluate the health risk of air pollution using biomarkers.

Expression levels of neuroimmune biomarkers in hypothalamus of allergic mice after phthalate exposure

Previously, we demonstrated that maternal exposure to phthalates enhances atopic dermatitis in male mouse offspring. However, whether phthalate exposure affects neuroimmune biomarkers in allergic mice has not yet been studied. Di-(2-ethylhexyl) phthalate (DEHP) and di-isononyl phthalate (DINP) are environmental chemicals that are commonly used as plasticizers. This study was designed to investigate the expression levels of neuroimmune biomarkers in the hypothalamus of a murine model of allergic asthma after phthalate exposure throughout juvenility until adulthood. Six-week-old C3H/HeJ Jcl male mice were treated with DEHP or DINP (0, 0.02, 0.4 or 8 nmol per body per week) and ovalbumin (OVA; 1 µg per body per 2 weeks) for 7 weeks intratracheally. On the day after the completion of the phthalate and OVA treatment, the hypothalamus from each mouse was collected, and the mRNA expression levels of neuroimmune biomarkers were examined using a real-time RT-PCR analysis. The mRNA expression levels of the proinflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α, the chemokine CCL3, the transcription factor nuclear factor (NF)-κB, the oxidative stress marker heme-oxygenase (HO)1, a nerve growth factor, and the microglia marker Iba1 were remarkably up-regulated in the hypothalami of mice treated with 8 nmol of DEHP in the presence of the allergen. However, no significant changes were observed, except for reductions in the TNF-α and CCL2 mRNA levels, in mice exposed to DINP combined with the allergen. This study is the first report to show that high-dose DEHP exposure throughout juvenility until adulthood may induce neuroinflammation by modulating neuroimmune biomarkers in the hypothalami of allergic mice.

Cultured human peripheral blood mononuclear cells alter their gene expression when challenged with endocrine-disrupting chemicals

Endocrine disrupting chemicals (EDCs) have the potential to interfere with the hormonal system and may negatively influence human health. Microarray analysis was used in this study to investigate differential gene expression in human peripheral blood cells (PBMCs) after in vitro exposure to EDCs. PBMCs, isolated from blood samples of four male and four female healthy individuals, were exposed in vitro for 18h to either a dioxin-like polychlorinated biphenyl (PCB126, 1μM), a non-dioxin-like polychlorinated biphenyl (PCB153, 10μM), a brominated flame retardant (BDE47, 10μM), a perfluorinated alkyl acid (PFOA, 10μM) or bisphenol (BPA, 10μM). ANOVA analysis revealed a significant change in the expression of 862 genes as a result of EDC exposure. The gender of the donors did not affect gene expression. Hierarchical cluster analysis created three groups and clustered: (1) PCB126-exposed samples, (2) PCB153 and BDE47, (3) PFOA and BPA. The number of differentially expressed genes varied per compound and ranged from 60 to 192 when using fold change and multiplicity corrected p-value as filtering criteria. Exposure to PCB126 induced the AhR signaling pathway. BDE47 and PCB153 are known to disrupt thyroid metabolism and exposure influenced the expression of the nuclear receptors PPARγ and ESR2, respectively. BPA and PFOA did not induce significant changes in the expression of known nuclear receptors. Overall, each compound produced a unique gene expression signature affecting pathways and GO processes linked to metabolism and inflammation. Twenty-nine genes were significantly altered in expression under all experimental conditions. Six of these genes (HSD11B2, MMP11, ADIPOQ, CEL, DUSP9 and TUB) could be associated with obesity and metabolic syndrome. In conclusion, microarray analysis identified that PBMCs altered their gene expression response in vitro when challenged with EDCs. Our screening approach has identified a number of gene candidates that warrant further study.

Secondhand smoke in combination with ambient air pollution exposure is associated with increasedx CpG methylation and decreased expression of IFN-γ in T effector cells and Foxp3 in T regulatory cells in children

BACKGROUND

Secondhand smoke (SHS) and ambient air pollution (AAP) exposures have been associated with increased prevalence and severity of asthma and DNA modifications of immune cells. In the current study, we examined the association between SHS and AAP with DNA methylation and expression of interferon-gamma (IFN-γ) and forkhead box protein 3 (Foxp3) in T cell populations.

METHODS

Subjects 7-18 years old were recruited from Fresno (high AAP; n = 62) and Stanford, CA (low AAP; n = 40) and divided into SHS-exposed (Fresno: n = 31, Stanford: n = 6) and non-SHS-exposed (nSHS; Fresno: n = 31, Stanford: n = 34) groups. T cells purified from peripheral blood were assessed for levels of DNA methylation and expression of IFN-γ (in effector T cells) or Foxp3 (in regulatory T cells).

RESULTS

Analysis showed a significant increase in mean % CpG methylation of IFN-γ and Foxp3 associated with SHS exposure (IFN-γ: FSHS 62.10%, FnSHS 41.29%, p < 0.05; SSHS 46.67%, SnSHS 24.85%, p < 0.05; Foxp3: FSHS 74.60%, FnSHS 54.44%, p < 0.05; SSHS 62.40%, SnSHS 18.41%, p < 0.05) and a significant decrease in mean transcription levels of both genes (IFN-γ: FSHS 0.75, FnSHS 1.52, p < 0.05; SHS 2.25, nSHS 3.53, p < 0.05; Foxp3: FSHS 0.75, FnSHS 3.29, p < 0.05; SSHS 4.8, SnSHS 7.2, p < 0.05). AAP was also associated with hypermethylation (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05) and decreased transcription of both genes (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05). Average methylation between AAP- and SHS-only exposures was not significantly different (IFN-γ: p = 0.15; Foxp3: p = 0.27), nor was Foxp3 expression (p = 0.08); IFN-γ expression was significantly decreased in AAP-only subjects (p < 0.05).

CONCLUSIONS

Exposures to SHS and AAP are associated with significant hypermethylation and decreased expression of IFN-γ in Teffs and Foxp3 in Tregs. Relative contributions of each exposure to DNA modification and asthma pathogenesis warrant further investigation.

A new framework for childhood health promotion: the role of policies and programs in building capacity and foundations of early childhood health

Although the connection between early life experiences and later health is becoming increasingly clear, what is needed, now, is a new organizing framework for childhood health promotion, grounded in the latest science. We review the evidence base to identify the steps in the overall pathway to ensuring better health for all children. A key factor in optimizing health in early childhood is building capacities of parents and communities. Although often overlooked, capacities are integral to building the foundations of lifelong health in early childhood. We outline a framework for policymakers and practitioners to guide future decision-making and investments in early childhood health promotion.

Perinatal stress, brain inflammation and risk of autism-review and proposal

BACKGROUND

Autism Spectrum Disorders (ASD) are neurodevelopmental disorders characterized by varying deficits in social interactions, communication, and learning, as well as stereotypic behaviors. Despite the significant increase in ASD, there are few if any clues for its pathogenesis, hampering early detection or treatment. Premature babies are also more vulnerable to infections and inflammation leading to neurodevelopmental problems and higher risk of developing ASD. Many autism "susceptibility" genes have been identified, but "environmental" factors appear to play a significant role. Increasing evidence suggests that there are different ASD endophenotypes.

DISCUSSION

We review relevant literature suggesting in utero inflammation can lead to preterm labor, while insufficient development of the gut-blood-brain barriers could permit exposure to potential neurotoxins. This risk apparently may increase in parents with "allergic" or autoimmune problems during gestation, or if they had been exposed to stressors. The presence of circulating auto-antibodies against fetal brain proteins in mothers is associated with higher risk of autism and suggests disruption of the blood-brain-barrier (BBB). A number of papers have reported increased brain expression or cerebrospinal fluid (CSF) levels of pro-inflammatory cytokines, especially TNF, which is preformed in mast cells. Recent evidence also indicates increased serum levels of the pro-inflammatory mast cell trigger neurotensin (NT), and of extracellular mitochondrial DNA (mtDNA), which is immunogenic. Gene mutations of phosphatase and tensin homolog (PTEN), the negative regulator of the mammalian target of rapamycin (mTOR), have been linked to higher risk of autism, but also to increased proliferation and function of mast cells.

SUMMARY

Premature birth and susceptibility genes may make infants more vulnerable to allergic, environmental, infectious, or stress-related triggers that could stimulate mast cell release of pro-inflammatory and neurotoxic molecules, thus contributing to brain inflammation and ASD pathogenesis, at least in an endophenotype of ASD patients.

Tipping the balance of autism risk: potential mechanisms linking pesticides and autism

BACKGROUND

Autism spectrum disorders (ASDs) have been increasing in many parts of the world and a portion of cases are attributable to environmental exposures. Conclusive replicated findings have yet to appear on any specific exposure; however, mounting evidence suggests gestational pesticides exposures are strong candidates. Because multiple developmental processes are implicated in ASDs during gestation and early life, biological plausibility is more likely if these agents can be shown to affect core pathophysiological features.

OBJECTIVES

Our objectives were to examine shared mechanisms between autism pathophysiology and the effects of pesticide exposures, focusing on neuroexcitability, oxidative stress, and immune functions and to outline the biological correlates between pesticide exposure and autism risk.

METHODS

We review and discuss previous research related to autism risk, developmental effects of early pesticide exposure, and basic biological mechanisms by which pesticides may induce or exacerbate pathophysiological features of autism.

DISCUSSION

On the basis of experimental and observational research, certain pesticides may be capable of inducing core features of autism, but little is known about the timing or dose, or which of various mechanisms is sufficient to induce this condition.

CONCLUSIONS

In animal studies, we encourage more research on gene × environment interactions, as well as experimental exposure to mixtures of compounds. Similarly, epidemiologic studies in humans with exceptionally high exposures can identify which pesticide classes are of greatest concern, and studies focused on gene × environment are needed to determine if there are susceptible subpopulations at greater risk from pesticide exposures.

Fetal and neonatal endocrine disruptors

Endocrine disruptors are substances commonly encountered in every setting and condition in the modern world. It is virtually impossible to avoid the contact with these chemical compounds in our daily life. Molecules defined as endocrine disruptors constitute an extremely heterogeneous group and include synthetic chemicals used as industrial solvents/lubricants and their by-products. Natural chemicals found in human and animal food (phytoestrogens) also act as endocrine disruptors. Different from adults, children are not exposed only to chemical toxins in the environment but may also be exposed during their intrauterine life. Hundreds of toxic substances, which include neuro-immune and endocrine toxic chemical components that may influence the critical steps of hormonal, neurological and immunological development, may affect the fetus via the placental cord and these substances may be excreted in the meconium. Children and especially newborns are more sensitive to environmental toxins compared to adults. Metabolic pathways are immature, especially in the first months of life. The ability of the newborn to metabolize, detoxify and eliminate many toxins is different from that of the adults. Although exposures occur during fetal or neonatal period, their effects may sometimes be observed in later years. Further studies are needed to clarify the effects of these substances on the endocrine system and to provide evidence for preventive measures.

Differential gene expression and a functional analysis of PCB-exposed children: understanding disease and disorder development

The goal of the present study is to understand the probable molecular mechanism of toxicities and the associated pathways related to observed pathophysiology in high PCB-exposed populations. We have performed a microarray-based differential gene expression analysis of children (mean age 46.1 months) of Central European descent from Slovak Republic in a well-defined study cohort. The subset of children having high blood PCB concentrations (>75 percentile) were compared against their low PCB counterparts (<25 percentile), with mean lipid-adjusted PCB values of 3.02±1.3 and 0.06±0.03 ng/mg of serum lipid, for the two groups, respectively (18.1±4.4 and 0.3±0.1 ng/ml of serum). The microarray was conducted with the total RNA from the peripheral blood mononuclear cells of the children using an Affymetrix platform (GeneChip Human genome U133 Plus 2.0 Array) and was analyzed by Gene Spring (GX 10.0). A highly significant set of 162 differentially expressed genes between high and low PCB groups (p value <0.00001) were identified and subsequently analyzed using the Ingenuity Pathway Analysis tool. The results indicate that Cell-To-Cell Signaling and Interaction, Cellular Movement, Cell Signaling, Molecular Transport, and Vitamin and Mineral Metabolism were the major molecular and cellular functions associated with the differentially altered gene set in high PCB-exposed children. The differential gene expressions appeared to play a pivotal role in the development of probable diseases and disorders, including cardiovascular disease and cancer, in the PCB-exposed population. The analyses also pointed out possible organ-specific effects, e.g., cardiotoxicity, hepatotoxicity and nephrotoxicity, in high PCB-exposed subjects. A few notable genes, such as BCL2, PON1, and ITGB1, were significantly altered in our study, and the related pathway analysis explained their plausible involvement in the respective disease processes, as mentioned. Our results provided insight into understanding the associated molecular mechanisms of complex gene-environment interactions in a PCB-exposed population. Future endeavors of supervised genotyping of pathway-specific molecular epidemiological studies and population biomarker validations are already underway to reveal individual risk factors in these PCB-exposed populations.

The kinetics of cell surface receptor expression in children perinatally exposed to polychlorinated biphenyls

Exposure to polychlorinated biphenyls (PCBs) during pre-natal and early life can alter normal immune system development. Blood specimens from newborns, 6-, and 16-month-old infants were collected in the Michalovce and Svidnik/Stropkov districts, areas with, respectively, high and low environmental PCB contamination, and lymphocyte receptor expression was evaluated by multi-color flow cytometry. The results indicate that the percentage of lymphoid dendritic cells (DC) and naïve/resting T-lymphocytes were significantly increased at 6-months in Michalovce as compared to the same cell types in cord blood samples (p < 0.001), whereas natural regulatory T-lymphocytes and suppressor inducer T-lymphocytes were reduced (p < 0.001). Overall, a positive linear correlation of terminally differentiated effector memory (TEM) T-lymphocyte population with age, but a negative linear correlation for myeloid DC from birth to 6-months in both regions were found. Michalovce samples indicated significantly higher expression of memory T-lymphocytes (birth, 6(th), and 16(th) month), TEM T-lymphocytes (birth and 6(th) month), and lymphoid DC (6(th) month) compared to the Svidnik/Stropkov regions. After adjustment for relevant covariates, such as maternal age, parity, season of birth, breastfeeding, birth weight, and gender, the myeloid DC, suppressor inducer T-lymphocytes, truly naïve helper/inducer T-lymphocytes, and TEM T-lymphocytes remained significantly different between districts in cord blood samples. The multivariate analysis models for 6- and 16-month samples showed district differences in all cellular determinants, except for lymphoid DC and macrophage-like cells. This study provides the first evidence that pre-natal and early post-natal exposure to PCBs affects the dynamics of cell surface receptor expression on lymphoid DC and DC-like cells, suggesting impaired immunologic development following pre-natal and early post-natal PCB exposure.

Brief report: "allergic symptoms" in children with Autism Spectrum Disorders. More than meets the eye?

Many children with Autism Spectrum Disorders (ASD) have either family and/or personal history of "allergic symptomatology", often in the absence of positive skin or RAST tests. These symptoms may suggest mast cell activation by non-allergic triggers. Moreover, children with mastocytosis or mast cell activation syndrome (MCAS), a spectrum of rare diseases characterized by increased number of activated mast cells in many organs, appear to have ASD at a rate tenfold higher (1/10 children) than that of the general population (1/100 children). Mast cell activation by allergic, infectious, environmental and stress-related triggers, especially perinatally, would release pro-inflammatory and neurotoxic molecules. We speculate these could disrupt the gut-blood-brain barriers, thus contributing to brain inflammation and ASD pathogenesis. Increased mast cell responsiveness may define at least a subgroup of ASD subjects, who could benefit from inhibition of mast cell activation.

Long-lived epigenetic interactions between perinatal PBDE exposure and Mecp2308 mutation

The widespread use of persistent organic polybrominated diphenyl ethers (PBDEs) as commercial flame retardants has raised concern about potential long-lived effects on human health. Epigenetic mechanisms, such as DNA methylation, are responsive to environmental influences and have long-lasting consequences. Autism spectrum disorders (ASDs) have complex neurodevelopmental origins whereby both genetic and environmental factors are implicated. Rett syndrome is an X-linked ASD caused by mutations in the epigenetic factor methyl-CpG binding protein 2 (MECP2). In this study, an Mecp2 truncation mutant mouse (Mecp2(308)) with social behavioral defects was used to explore the long-lasting effects of PBDE exposure in a genetically and epigenetically susceptible model. Mecp2(308/+) dams were perinatally exposed daily to 2,2',4,4'-tetrabromodiphenyl ether 47 (BDE-47) and bred to wild-type C57BL/6J males, and the offspring of each sex and genotype were examined for developmental, behavioral and epigenetic outcomes. Perinatal BDE-47 exposure negatively impacted fertility of Mecp2(308/+) dams and preweaning weights of females. Global hypomethylation of adult brain DNA was observed specifically in female offspring perinatally exposed to BDE-47 and it coincided with reduced sociability in a genotype-independent manner. A reversing interaction of Mecp2 genotype on BDE-47 exposure was observed in a short-term memory test of social novelty that corresponded to increased Dnmt3a levels specifically in BDE-47-exposed Mecp2(308/+) offspring. In contrast, learning and long-term memory in the Morris water maze was impaired by BDE-47 exposure in female Mecp2(308/+) offspring. These results demonstrate that a genetic and environmental interaction relevant to social and cognitive behaviors shows sexual dimorphism, epigenetic dysregulation, compensatory molecular mechanisms and specific behavioral deficits.

Analysis of the toxicogenomic effects of exposure to persistent organic pollutants (POPs) in Slovakian girls: correlations between gene expression and disease risk

The chemical composition of persistent organic pollutants (POPs) in the environment is not uniform throughout the world, and these contaminants contain many structurally different lipophilic compounds. In a well-defined study cohort in the Slovak Republic, the POP chemicals present in the peripheral blood of exposed children were chemically analyzed. The chemical analysis data revealed that the relative concentration and profile of structurally different organic pollutants, including polychlorinated biphenyls (PCBs), 2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), 2,2'-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (p,p'-DDT), hexachlorobenzene (HCB) and β-hexachlorocyclohexane (β-HCH), may vary from individual to individual, even within the same exposure area. These chemicals can be broadly classified into two groups. The first group, the PCB congeners, primarily originated from industrial compounds and their byproducts. The second group of compounds originated from or was commonly used in the agricultural sector (e.g., DDT, HCB). The objective of this study was to examine the effects of the two POP exposure profiles on gene expression. For the study population, we selected pre-pubertal girls (mean age of 46.2±1.4 months) with high POP concentrations in their blood (>75% tile of total POP) and classified them in the high 'PCB' group when the total PCB concentration was significantly higher than the total concentration of other POP components and in the 'Other Than PCB' (OTP) group, when the total PCB concentration was significantly lower than the concentration of the other major POP constituents. A matched control group of girls (<25% tile of total POP) was selected for comparison purpose (n=5 per group). Our aims were to determine whether there were any common effects of high POP exposure at a toxicogenomic level and to investigate how exposure may affect physiological functions of the children in two different exposure scenarios. Global gene expression analysis using a microarray (Affymetrix Gene Chip Human genome U133 Plus 2.0 Array) platform was conducted on the total RNA of peripheral blood mononuclear cells from the girls. The results were analyzed by Partek GS, Louis, MI, which identified twelve genes (ATAD2B, BIVM, CD96, CXorf39, CYTH1 ETNK1, FAM13A, HIRA, INO80B, ODG1, RAD23B, and TSGA14) and two unidentified probe sets, as regulated differentially in both the PCB and OTP groups against the control group. The qRT-PCR method was used to validate the microarray results. The Ingenuity Pathway Analysis (IPA) software package identified the possible molecular impairments and disease risks associated with each gene set. Connective tissue disorders, genetic disorders, skeletal muscular disorders and neurological diseases were associated with the 12 common genes. The data therefore identified the potential molecular effects of POP exposure on a genomic level. This report underscores the importance of further study to validate the results in a random population and to evaluate the use of the identified genes as biomarkers for POP exposure.

Effect of polychlorinated biphenyls 118 and 153 on Th1/Th2 cells differentiation

The objective of this study was evaluate the effect of coplanar polychlorinated biphenyls (PCB) 118-congener (PCB like-dioxin) and noncoplanar PCB 153-congener (PCB no like-dioxin) on differentiation of humans T-CD4+ lymphocytes into Th1 or Th2 subpopulations. Peripheral blood mononuclear cells (PBMC) were isolated from healthy volunteers (aged 25-30 years); T-CD4+ lymphocytes were separated from PBMC. Then, the differentiation of T-CD4+ cells into Th1 or Th2 subpopulation was performed and the intracellular cytokines analyses were assessed. No effect on IFNγ (produced by Th1 cells) production was observed when the cells were treated with both PCBs congeners. However, the PCB 118-congener induced an increase of IL-4-producing T-CD4 cells (produced by Th2 cells), PCB153 not exerted any effect on IL-4 production. The clinical significance of our data is uncertain, therefore, more studies are necessary in order to elucidate the effects generated in exposed human individual.

Maternal diesel inhalation increases airway hyperreactivity in ozone-exposed offspring

Air pollutant exposure is linked with childhood asthma incidence and exacerbations, and maternal exposure to airborne pollutants during pregnancy increases airway hyperreactivity (AHR) in offspring. To determine if exposure to diesel exhaust (DE) during pregnancy worsened postnatal ozone-induced AHR, timed pregnant C57BL/6 mice were exposed to DE (0.5 or 2.0 mg/m(3)) 4 hours daily from Gestation Day 9-17, or received twice-weekly oropharyngeal aspirations of the collected DE particles (DEPs). Placentas and fetal lungs were harvested on Gestation Day 18 for cytokine analysis. In other litters, pups born to dams exposed to air or DE, or to dams treated with aspirated diesel particles, were exposed to filtered air or 1 ppm ozone beginning the day after birth, for 3 hours per day, 3 days per week for 4 weeks. Additional pups were monitored after a 4-week recovery period. Diesel inhalation or aspiration during pregnancy increased levels of placental and fetal lung cytokines. There were no significant effects on airway leukocytes, but prenatal diesel augmented ozone-induced elevations of bronchoalveolar lavage cytokines at 4 weeks. Mice born to the high-concentration diesel-exposed dams had worse ozone-induced AHR, which persisted in the 4-week recovery animals. Prenatal diesel exposure combined with postnatal ozone exposure also worsened secondary alveolar crest development. We conclude that maternal inhalation of DE in pregnancy provokes a fetal inflammatory response that, combined with postnatal ozone exposure, impairs alveolar development, and causes a more severe and long-lasting AHR to ozone exposure.

Dynamics of lymphocyte subsets in children living in an area polluted by polychlorinated biphenyls

Immune system development, particularly in the pre-natal and early post-natal periods, has far-reaching health consequences during childhood, as well as throughout life. Exposure to poly-chlorinated biphenyls (PCBs) during pre-natal and early life has been previously associated with changes in the incidence of infectious and allergic diseases in children, and humoral immunity alterations. Lymphocyte immunophenotyping is an important tool in the diagnosis of immunologic and hematologic disorders. This study used a lysed whole blood method for analysis of lymphocyte sub-populations in samples from children born and living in two districts: a highly-contaminated area (Michalovce) and one (Svidnik/Stropkov) with ≈ 2-fold lower environmental PCB levels. The percentages of B-lymphocytes (CD19(+)), activated HLADR(+)CD19(+) cells, and CD8(+) T-lymphocytes significantly increased at 6- and 16-months-of-age in both selected regions as compared to in cord blood values (p < 0.001). Levels of CD3(+) cells increased significantly (from 61 to 65%) in samples from Michalovce (p < 0.01). Levels of CD4(+) T-lymphocytes declined 10% among 16-month-olds in both regions (Michalovce at p < 0.001 and Svidnik/Stropkov at p < 0.01). Natural killer (NK) cell levels decreased 50% in Michalovce 6- and 16-month-old children and 42% among 6-month-olds in Svidnik/Stropkov (p < 0.001). Compared with the less-contaminated region, Michalovce samples showed significantly higher expression of CD3(+) T-lymphocytes, B-lymphocytes, and activated B-lymphocytes, whereas NK cells were less expressed. Even after adjustment for selected covariates, e.g., maternal cigarette smoking, age, parity, ethnicity, birth weight, and gender of infant, the levels of CD19(+), HLADR(+)CD19(+), and CD3(-)CD(16 + 56)(+) cells were seen to remain significantly different between the districts. These results showed that early-life environmental PCB exposure was associated with fluctuations in major lymphocyte subsets in children, suggesting that there is a post-natal immune system response to PCB exposures.

Mycobacterium paratuberculosis and autism: is this a trigger?

Autism is a heterogeneous group of life-long neurologic problems that begin in childhood. Success in efforts to understand and treat autism has been mostly elusive. The role of autoimmunity in autism has gained recognition both for associated systemic autoimmune disease and the presence of brain autoantibodies in autistic children and their family members. There is an acknowledged genetic susceptibility to autism--most notably allotypes of complement C4. C4 defects are associated with several autoimmune diseases and also confer susceptibility to mycobacterial infections. Mycobacterium avium ss. paratuberculosis (MAP) causes an enteric inflammatory disease in ruminant animals (Johne's disease) and is the putative cause of the very similar Crohn's disease in humans. Humans are widely exposed to MAP in food and water. MAP has been also linked to ulcerative colitis, irritable bowel syndrome, sarcoidosis, Blau syndrome, autoimmune (Type 1) diabetes, Hashimoto's thyroiditis and multiple sclerosis. Environmental agents are thought to trigger autism in the genetically at risk. Molecular mimicry is the proposed mechanism by which MAP is thought to trigger autoantibodies. Autoantibodies to brain myelin basic protein (MBP) is a common feature of autism. This article considers the subset of autoimmunity-related autism patients and postulates that MAP, through molecular mimicry to its heat shock protein HSP65, triggers autism by stimulating antibodies that cross react with myelin basic protein (MBP).

Whole genome expression in peripheral-blood samples of workers professionally exposed to polycyclic aromatic hydrocarbons

This study aims to examine global gene expression profiles before and after the work-shift among coke-oven workers (COWs). COWs work six consecutive days and then take two days off. Two blood and urine samples in each worker were collected before starting to work after two days off and end-of-shift in the sixth day of work in 2009. Altered gene expressions (ratio of gene expression levels between end-of-shift and preshift work) were performed by a Human OneArray expression system which probes ~30,000-transcription expression profiling of human genes. Sixteen workers, all men, were enrolled in this study. Median urinary 1-hydroxypyrene (1OHP) levels (μmol/mol creatinine) in end-of-shift work were significantly higher than those in preshift work (2.58 vs 0.29, p = 0.0002). Among the 20,341 genes which passed experimental quality control, 26 gene expression changes, 7 positive and 19 negative, were highly correlated with across-the-shift urinary 1OHP levels (end-of-shift-preshift 1OHP) (p-value <0.001). The high and low exposure groups of across-the-shift urinary 1OHP levels dichotomized in ~2.00 μmol/mol creatinine were able to be distinguished by these 26 genes. Some of them are known to be involved in apoptosis, chromosome stability/DNA repair, cell cycle control/tumor suppressor, cell adhesion, development/spermatogenesis, immune function, and neuronal cell function. These findings in COWs will be an ideal model to study the relationship of PAH exposure with acute changes of gene expressions.

Exposure to moderate air pollution during late pregnancy and cord blood cytokine secretion in healthy neonates

Background/Objectives

Ambient air pollution can alter cytokine concentrations as shown in vitro and following short-term exposure to high air pollution levels in vivo. Exposure to pollution during late pregnancy has been shown to affect fetal lymphocytic immunophenotypes. However, effects of prenatal exposure to moderate levels of air pollutants on cytokine regulation in cord blood of healthy infants are unknown.

Methods

In a birth cohort of 265 healthy term-born neonates, we assessed maternal exposure to particles with an aerodynamic diameter of 10 µm or less (PM₁₀), as well as to indoor air pollution during the last trimester, specifically the last 21, 14, 7, 3 and 1 days of pregnancy. As a proxy for traffic-related air pollution, we determined the distance of mothers' homes to major roads. We measured cytokine and chemokine levels (MCP-1, IL-6, IL-10, IL-1ß, TNF-α and GM-CSF) in cord blood serum using LUMINEX technology. Their association with pollution levels was assessed using regression analysis, adjusted for possible confounders.

Results

Mean (95%-CI) PM₁₀ exposure for the last 7 days of pregnancy was 18.3 (10.3–38.4 µg/m³). PM₁₀ exposure during the last 3 days of pregnancy was significantly associated with reduced IL-10 and during the last 3 months of pregnancy with increased IL-1ß levels in cord blood after adjustment for relevant confounders. Maternal smoking was associated with reduced IL-6 levels. For the other cytokines no association was found.

Conclusions

Our results suggest that even naturally occurring prenatal exposure to moderate amounts of indoor and outdoor air pollution may lead to changes in cord blood cytokine levels in a population based cohort.

Global gene expression and Ingenuity biological functions analysis on PCBs 153 and 138 induced human PBMC in vitro reveals differential mode(s) of action in developing toxicities

Several reports have indicated that low level of polychlorinated biphenyl (PCB) exposure can adversely affect a multitude of physiological disorders and diseases in in vitro, in vivo, and as reported in epidemiological studies. This investigation is focused on the possible contribution of two most prevalent PCB congeners in vitro in developing toxicities. We used PCBs 138 and 153 at the human equivalence level as model agents to test their specificity in developing toxicities. We chose a global approach using oligonucleotide microarray technology to investigate modulated gene expression for biological effects, upon exposure of PCBs, followed by Ingenuity Pathway Analysis (IPA), to understand the underlying consequence in developing disease and disorders. We performed in vitro studies with human peripheral blood mononuclear cells (PBMC), where PBMC cells were exposed to respective PCBs for 48 h. Overall, our observation on gene expression indicated that PCB produces a unique signature affecting different pathways, specific for each congener. While analyzing these data through IPA, the prominent and interesting disease and disorders were neurological disease, cancer, cardiovascular disease, respiratory disease, as well as endocrine system disorders, genetic disorders, and reproductive system disease. They showed strong resemblances with in vitro, in vivo, and in the epidemiological studies. A distinct difference was observed in renal and urological diseases, organisimal injury and abnormalities, dental disease, ophthalmic disease, and psychological disorders, which are only revealed by PCB 138 exposure, but not in PCB 153. The present study emphasizes the challenges of global gene expression in vitro and was correlated with the results of exposed human population. The microarray results give a molecular mechanistic insight and functional effects, following PCB exposure. The extent of changes in genes related to several possible mode(s) of action highlights the changes in cellular functions and signaling pathways that play major roles. In addition to understanding the pathways related to mode of action for chemicals, these data could lead to the identification of genomic signatures that could be used for screening of chemicals for their potential to cause disease and developmental disorders.

PCDD, PCDF, PCB and PBDE concentrations in breast milk of mothers residing in selected areas of Slovakia

The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polybrominated diphenylethers (PBDEs) in 33 breast milk samples collected in 2006-2007 from primipara mothers close to four industrial areas of Slovak Republic were determined. The total PCDDs/PCDFs and dl-PCBs expressed as TEQ based on WHO TEFs 1998 in breast milk samples varied from 5.0 to 51.8 pg g(-1) fat (median: 13.1 pg g(-1) fat; mean: 18.0 pg g(-1) fat). The measurements of seven PBDE congeners (IUPAC No. 28, 47, 99, 100, 153, 154, and 183) were performed for the first time in human milk from Slovakia. PBDE levels ranged between 0.22 and 1.62 ng g(-1) fat, with median and mean value of 0.43 ng g(-1) fat and 0.57 ng g(-1) fat respectively. No statistically significant differences were observed between studied areas in total PBDE concentrations. Furthermore, this study presents first results concerning the daily intake (DI) of PCDDs/PCDFs and dioxin-like compounds for the most vulnerable breast-fed infant population in Slovakia. The total PCDD/PCDF and dl-PCB DI for an infant during the first 2 months of life was estimated in a range from 14.4 to 230 pg TEQ kg(-1)b.w., with a median value of 58.9 pg TEQ kg(-1)b.w.. The DI values substantially exceeded the tolerable daily intake (TDI) 1-4 pg TEQ kg(-1)b.w. recommended by WHO. The dietary infant intake concerning PBDEs was estimated to be between 0.69 and 7.1 ng kg(-1)b.w.d(-1), with median value of 1.7 ng kg(-1)b.w.d(-1).

Environmental toxicants and the developing immune system: a missing link in the global battle against infectious disease?

There is now compelling evidence that developmental exposure to chemicals from our environment contributes to disease later in life, with animal models supporting this concept in reproductive, metabolic, and neurodegenerative diseases. In contrast, data regarding how developmental exposures impact the susceptibility of the immune system to functional alterations later in life are surprisingly scant. Given that the immune system forms an integrated network that detects and destroys invading pathogens and cancer cells, it provides the body's first line of defense. Thus, the consequences of early life exposures that reduce immune function are profound. This review summarizes available data for pollutants such as cigarette smoke and dioxin-like compounds, which consistently support the idea that developmental exposures critically impact the immune system. These findings suggest that exposure to common chemicals from our daily environment represent overlooked contributors to the fact that infectious diseases remain among the top five causes of death worldwide.

The promise and the pitfalls of autism research: an introductory note for new autism researchers

The last decade has seen an enormous growth in the quantity of research directed at understanding the biological underpinnings of autism spectrum disorders. This increase has been spurred on, in part, by research funding provided through private, parent advocacy groups. While increased funding and entry into autism research by scientists from many disciplines has facilitated the speed of discoveries germane to establishing the etiologies of autism, there remain a number of roadblocks to understanding autism sufficiently well to foster new treatments. This short article provides a brief overview of some of the achievements and some of the difficulties in conducting autism research.

Mast cell activation and autism

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by varying degrees of dysfunctional communication and social interactions, repetitive and stereotypic behaviors, as well as learning and sensory deficits. Despite the impressive rise in the prevalence of autism during the last two decades, there are few if any clues for its pathogenesis, early detection or treatment. Increasing evidence indicates high brain expression of pro-inflammatory cytokines and the presence of circulating antibodies against brain proteins. A number of papers, mostly based on parental reporting on their children's health problems, suggest that ASD children may present with "allergic-like" problems in the absence of elevated serum IgE and chronic urticaria. These findings suggest non-allergic mast cell activation, probably in response to environmental and stress triggers that could contribute to inflammation. In utero inflammation can lead to preterm labor and has itself been strongly associated with adverse neurodevelopmental outcomes. Premature babies have about four times higher risk of developing ASD and are also more vulnerable to infections, while delayed development of their gut-blood-brain barriers makes exposure to potential neurotoxins likely. Perinatal mast cell activation by infectious, stress-related, environmental or allergic triggers can lead to release of pro-inflammatory and neurotoxic molecules, thus contributing to brain inflammation and ASD pathogenesis, at least in a subgroup of ASD patients. This article is part of a Special Issue entitled: Mast cells in inflammation.

Trans-generational and neonatal humoral immune responses in West Greenland sledge dogs (Canis familiaris) exposed to organohalogenated environmental contaminants

Previous investigations in the Arctic have suggested OHC (organohalogen contaminant) induced immune toxic effects on e.g. polar bears (Ursus maritimus). We therefore studied the dietary impact from minke whale blubber (Balaenoptera acutorostrata), rich in polyunsaturated fatty acids and OHCs, on the humoral immunity of 7 captive West Greenland sledge dog (Canis familiaris) bitches and their 4 pups constituting a sentinel model species for polar bears. A control group was composed of 8 bitches and their 5 pups all fed pork (Suis scrofa) fat. The study included serum IgG measurements (bitches and pups) and specific immune responses towards tetanus toxoid (bitches) and diphtheria toxoid (pups) as well as influenza virus (pups). The analyses showed that IgG concentrations were non-significantly lowest in exposed bitches and pups (t-test: all p>0.05). In addition, significant lower antibody response was detected in exposed pups immunized with influenza virus at age 3 months (t-test: both p<0.05). No clear group differences were found for tetanus toxoid in bitches and diphtheria toxoid in pups. The results suggest that the humoral immune system of sledge dogs may be suppressed by the dietary blubber composition of OHCs and polyunsaturated fatty acids while a larger follow-up study is recommended in order to investigate this relationship further.

Concentrations and determinants of organochlorine levels among pregnant women in Eastern Spain

Persistent organic pollutants (POPs) comprise a large variety of toxic substances with ample distribution. While exposure to these toxins occurs mainly through diet, maternal POP levels may be influenced by certain sociodemographic, environmental, or lifestyle factors. This is important given that these substances may have adverse effects on fetal development. The aim of this study is to examine the sociodemographic, environmental, lifestyle, and dietary determinants of the levels of hexachlorobenzene (HCB), b-hexachlorocyclohexane (b-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), and polychlorinated biphenyls (PCB congeners 118, 138, 153, 180) measured in the blood of pregnant women participating in a mother-child cohort study conducted in Valencia (Spain). The study population consisted of 541 pregnant women who formed part of the INMA (Childhood and the Environment) cohort (2004-2006). POP levels were determined in blood taken during the 12th week of pregnancy with the aid of gas chromatography with electron capture detection. Sociodemographic, environmental, and dietary information was obtained from a questionnaire. Multivariate Tobit regression models were constructed in order to assess the association between POP levels and selected covariates. The results showed that all the women had detectable levels of at least one of these compounds while in 43% of the subjects, all eight compounds were detected. The compounds found in the greatest number of women were 4,4'-DDE (100%) and PCBs 153 and 180 (95%). The most important determinants of high POP levels were the mother's age, country of origin, increased body mass index, and number of weeks of breastfeeding after previous pregnancies. With regard to diet, 4,4'-DDT and 4,4'-DDE levels increased with the intake of meat, fruit, and cereal. PCB 153 levels increased with the intake of seafood. The levels of HCB, b-HCH, 4,4'-DDT, and 4,4'-DDE observed in this study were slightly higher than in other studies, whereas the PCB levels were similar.

Neonatal immune function and inflammatory illnesses in later life: lessons to be learnt from the developing world?

With the emergence of allergic and autoimmune diseases in populations that have started to transit to a western lifestyle, there has been an increasing interest in the role of environmental factors modulating early immune function. Yet, most of the information concerning neonatal immune function has been derived from studies in westernized countries. We postulate that comparative studies of early immune development in children born under conditions that are typical for a westernized vs. that of a still more traditional setting will provide a crucial insight into the environmental-driven immunological mechanisms that are responsible for the world-wide rise in inflammatory disorders. In this review, we summarize the current understanding of early-life immune function in humans in general and the literature on some major lifestyle factors that may influence neonatal immune function and potentially the risk for disease in later life. An understanding of the mechanisms of 'prenatal/early-life programming' in populations living in traditional compared with modern societies is crucial to develop strategies to prevent a further rise in 'western diseases' such as allergic disorders. Indications exist that prenatal conditioning of the innate immune system by low-grade inflammatory responses is key to inducing more tightly regulated postnatal adaptive immune responses.

The impacts of organochlorines and other persistent pollutants on thyroid and metabolic health

High prevalence of thyroid and metabolic disorders has been repeatedly observed in the population living in the area of eastern Slovakia highly polluted by a mixture of PCBs, DDE and HCB since about 50 years ago. Among thyroid disorders, increase of thyroid volume as measured by ultrasound volumetry may be suggested as one of notable findings which appeared possibly related to increased OCs levels and to autoimmunity signs (e.g. positive thyroperoxidase antibodies in blood and/or hypoechogenicity image obtained by ultrasound), while some participation of individual susceptibility and also of immunogenic effect of OCs and iodine in this iodine replete country cannot be excluded. Another notable finding has been the increase of blood FT4 and TT3 positively related to high PCBs level. Such increased FT4 level has been found associated with TSH level in hyperthyroid range in about 2% of examined population from polluted area. High prevalence of thyroid autoimmune disorders strongly supported the assumption on impaired immune system and thus also on presumably increased prevalence of other autoimmune disorders in highly exposed population. In addition, markedly increased prevalence of prediabetes and diabetes significantly related to major OCs (PCBs, DDE and HCB) levels and accompanied by increasing level of cholesterol and triglycerides has been observed. The observations also suggested a role of prenatal exposure to OCs in the development of several adverse health signs (e.g. increased prevalence of thyroid antibodies, impaired fasting glucose level, increased thyroid volume, decreased thymus volume, decreased neurobehavioral performance, increased hearing and dental disorders) in young generation born to highly exposed mothers in polluted area.

Levels of organochlorines and lipids across pregnancy, delivery and postpartum periods in women from Northern Norway

The objective of this study was to investigate changes in the levels of common organochlorines (OCs) and lipids in maternal serum during and after pregnancy. A subset of 50 pregnant women from the North Norwegian Mother-and-Child Study was included in this study. Blood samples were collected during the 2(nd) trimester and postpartum (Day 3 and 6 weeks) in different regions of Northern Norway, and were analyzed for the Arctic Monitoring and Assessment Programme (AMAP) suite of OC contaminants. During the gestational period, both lipids and wet-weight OC levels peaked at birth and were the lowest at 6 weeks postpartum. When the OC concentrations were lipid-adjusted, this peaking was no longer evident. Wet-weight concentrations of OCs appear to be driven by the physiological lipid profiles and are interpreted to constitute biomarkers of lipidemia. It is suggested that this observation may have implications for the biomonitoring of individuals at risk of Type 2 diabetes. Both age and parity were strong predictors for the OCs measured, but no consistent association with body mass index (BMI) was evident. Independent of lipid-adjustment, all compounds were positively and significantly correlated with each other (within and across the three collection time periods). The peaking of OCs during pregnancy suggests that the period spanning the last weeks of the 3(rd) trimester and the early postpartum days constitutes an optimum sampling window purely from the analytical perspective.

Maternal micronutrient supplementation with zinc and β-carotene affects morbidity and immune function of infants during the first 6 months of life

BACKGROUND/OBJECTIVES

Micronutrient deficiencies are prevalent worldwide, and a major cause of infant death. Supplementation with multiple micronutrients during pregnancy might improve micronutrient status of the newborn, thereby reducing morbidity and death. Moreover, maternal supplementation might affect the newborn's immune development. Therefore, this study investigated the effects of maternal zinc and β-carotene supplementation on the infant's morbidity and immune function during the first 6 months of life.

SUBJECTS/METHODS

Mothers were supplemented during pregnancy with β-carotene and/or zinc, in addition to iron and folic acid, in a randomized, double-blind controlled trial. Newborn infants (n=136) were followed up for 6 months.

RESULTS

Infants born from mothers receiving zinc during pregnancy had significantly fewer episodes of diarrhoea than infants born from mothers not receiving zinc (0.2 and 0.4, respectively), but more episodes of cough (1.3 and 0.9 respectively) during the first 6 months. Maternal β-carotene supplementation had no effect on infants' morbidity. Cytokine production in the newborns was affected by maternal zinc and β-carotene supplementation, with zinc supplementation giving higher interleukin-6 production (16% higher), and β-carotene supplementation leading to lower interferon-γ production (36% lower).

CONCLUSIONS

This study shows that maternal supplementation with zinc and β-carotene affected the newborn's immune development in specific ways, but only maternal zinc supplementation significantly affected morbidity in the infants. Addition of zinc to routine iron and folic acid supplements for pregnant women could be an effective way to reduce diarrhoeal disease during the first 6 months of life, albeit at the expense of more episodes of cough.

Health effects from long-range transported contaminants in Arctic top predators: An integrated review based on studies of polar bears and relevant model species

The aim of this review is to provide a thorough overview of the health effects from the complexed biomagnified mixture of long-range transported industrial organochlorines (OCs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs) and mercury (Hg) on polar bear (Ursus maritimus) health. Multiple scientific studies of polar bears indicate negative relationships between exposure to these contaminants and health parameters; however, these are all of a correlative nature and do not represent true cause-and-effects. Therefore, information from controlled studies of farmed Norwegian Arctic foxes (Vulpes lagopus) and housed East and West Greenland sledge dogs (Canis familiaris) were included as supportive weight of evidence in the clarification of contaminant exposure and health effects in polar bears. The review showed that hormone and vitamin concentrations, liver, kidney and thyroid gland morphology as well as reproductive and immune systems of polar bears are likely to be influenced by contaminant exposure. Furthermore, exclusively based on polar bear contaminant studies, bone density reduction and neurochemical disruption and DNA hypomethylation of the brain stem seemed to occur. The range of tissue concentration, at which these alterations were observed in polar bears, were ca. 1-70,000 ng/g lw for OCs (blood plasma concentrations of some PCB metabolites even higher), ca. 1-1000 ng/g lw for PBDEs and for PFCs and Hg 114-3052 ng/g ww and 0.1-50 microg/g ww, respectively. Similar concentrations were found in farmed foxes and housed sledge dogs while the lack of dose response designs did not allow an estimation of threshold levels for oral exposure and accumulated tissue concentrations. Nor was it possible to pinpoint a specific group of contaminants being more important than others nor analyze their interactions. For East Greenland polar bears the corresponding daily SigmaOC and SigmaPBDE oral exposure was estimated to be 35 and 0.34 microg/kg body weight, respectively. Furthermore, PFC concentrations, at which population effect levels could occur, are likely to be reached around year 2012 for the East Greenland polar bear subpopulation if current increasing temporal trends continue. Such proposed reproductive population effects were supported by physiological based pharmacokinetic (PBPK) modelling of critical body residues (CBR) with risk quotients >or=1 for SigmaPCB, dieldrin, SigmaPFC and SigmaOHC (organohalogen contaminant). The estimated daily TEQ for East Greenland polar bears and East Greenland sledge dogs were 32-281-folds above WHO SigmaTEQ guidelines for humans. Compared to human tolerable daily intake (TDI), these were exceeded for PCBs, dieldrin, chlordanes and SigmaHCH in East Greenland polar bears. Comparisons like these should be done with caution, but together with the CBR modelling and T-score estimations, these were the only available tools for polar bear risk evaluation. In conclusion, polar bears seem to be susceptible to contaminant induced stress that may have an overall sub-clinical impact on their health and population status via impacts on their immune and reproductive systems.

Allergic disease: understanding how in utero events set the scene

Events and exposures in pregnancy can have critical effects on fetal development with lasting implications for subsequent health and disease susceptibility. There is growing interest in how modern environmental changes influence fetal immune development and contribute to the recent epidemic of allergy and other immune disorders. Rising rates of allergic disease in early infancy, together with pre-symptomatic differences in immune function at birth, suggest that antenatal events play a predisposing role in the development of disease. A number of environmental exposures in pregnancy can modify neonatal immune function including diet, microbial exposure and maternal smoking, and there is emerging evidence from animal models that these factors may have epigenetic effects on immune gene expression and disease susceptibility. Furthermore, functional genetic polymorphisms also alter individual vulnerability to the effects of these environmental exposures, highlighting the complexity of gene-environmental interactions in this period. All these observations underscore the need for ongoing research to understand the pathogenesis and rising incidence of disease in the hope of better strategies to reverse this.

A nested case-control study of intrauterine exposure to persistent organochlorine pollutants in relation to risk of type 1 diabetes

BACKGROUND

The incidence of type 1 diabetes in Europe is increasing at a rate of about 3% per year and there is also an increasing incidence throughout the world. Type 1 diabetes is a complex disease caused by multiple genetic and environmental factors. Persistent organochlorine pollutants (POPs) have been suggested as a triggering factor for developing childhood type 1 diabetes. The aim of this case-control study was to assess possible impacts of in utero exposure to POPs on type 1 diabetes.

METHODOLOGY/ PRINCIPAL FINDINGS

The study was performed as a case-control study within a biobank in Malmö, a city located in the Southern part of Sweden. The study included 150 cases (children who had their diagnosis mostly before 18 years of age) and 150 controls, matched for gender and day of birth. 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153) and the major DDT metabolite 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) were used as a biomarkers for POP exposure. When comparing the quartile with the highest maternal serum concentrations of PCB-153 with the other quartiles, an odds ratio (OR) of 0.73 (95% confidence interval [CI] 0.42, 1.27) was obtained. Similar results was obtained for p,p'-DDE (OR 0.56, 95% CI 0.29, 1.08).

CONCLUSIONS

The hypothesis that in utero exposure to POPs will trigger the risk for developing type 1 diabetes was not supported by the results. The risk estimates did, although not statistically significant, go in the opposite direction. However, it is not reasonable to believe that exposure to POPs should protect against type 1 diabetes.

Effects of mixtures of polychlorinated biphenyls, methylmercury, and organochlorine pesticides on hepatic DNA methylation in prepubertal female Sprague-Dawley rats

DNA methylation is one of the epigenetic mechanisms that regulates gene expression, chromosome structure, and stability. Our objective was to determine whether the DNA methylation system could be a target following in utero and postnatal exposure to human blood contaminants. Pregnant rats were dosed daily from gestation day 1 until postnatal day 21 with 2 dose levels of either organochlorine pesticides (OCP; 0.019 or 1.9 mg/kg/day), methylmercury chloride (MeHg; 0.02 or 2 mg/kg/day), polychlorinated biphenyls (PCBs; 0.011 or 1.1 mg/kg/day), or a mixture (Mix; 0.05, or 5 mg/kg/day) including all 3 groups of chemicals. Livers from 1 female offspring per litter were collected at postnatal day 29. Hepatic analysis revealed that the mRNA abundance for DNA methyltransferase (DNMT)-1, -3a, and -3b were significantly reduced by the high dose of PCB, that the high dose of MeHg also reduced mRNA levels for DNMT-1, and -3b, but that OCP had no significant effects compared with control. The high dose of PCB and Mix reduced the abundance of the universal methyl donor S-adenosylmethionine, and Mix also reduced global genome DNA methylation (5-methyl-deoxycytidine/5-methyl-deoxycytidine + deoxycytidine). The latter is consistent with pyrosequencing methylation analysis, revealing that the high-dose groups (except OCP) generally decreased the methylation of CpG sites (position -63 to -29) in the promoter of the tumor suppressor gene p16(INK4a). Overall, these hepatic results suggest that the DNA methylation system can be affected by exposure to high doses of blood contaminants, and that OCP is the least potent chemical group from the investigated mixtures.

Gene expression in the placenta: maternal stress and epigenetic responses

Successful placental development is crucial for optimal growth, development, maturation and survival of the embryo/fetus into adulthood. Numerous epidemiologic and experimental studies have demonstrated the profound influence of intrauterine environment on life, and the diseases to which one is subject as an adult. For the most part, these invidious influences, whether maternal hypoxia, protein or caloric deficiency or excess, and others, represent types of maternal stress. In the present review, we examine certain aspects of gene expression in the placenta as a consequence of maternal stressors. To examine these issues in a controlled manner, and in a species in which the genome has been sequenced, most of these reported studies have been performed in the mouse. Although each individual maternal stress is characterized by up- or down-regulation of specific genes in the placenta, functional analysis reveals some patterns of gene expression common to the several forms of stress. Of critical importance, these genes include those involved in DNA methylation and histone modification, cell cycle regulation, and related global pathways of great relevance to epigenesis and the developmental origins of adult health and disease.

Asthma and pregnancy: emerging evidence of epigenetic interactions in utero

PURPOSE OF REVIEW

Pregnancy is arguably the most critical period of developmental programming. Here, we particularly focus on the emerging paradigm that disease propensity is epigenetically determined by maternal exposures that have the capacity to activate or silence fetal genes through alterations in DNA and histone methylation, histone acetylation, and chromatin structure.

RECENT FINDINGS

The most notable recent candidate to emerge in this role has been dietary folate, a methyl donor clearly associated with changes in gene expression and disease susceptibility through gene hypermethylation. Animal studies also provide the first evidence that the allergy protective effects of microbial exposure in pregnancy may be mediated by changes in methylation of Th1 genes of the offspring. There is also emerging evidence that perinatal differences in immune function of allergy-prone newborns extend beyond previously recognized differences in effector T cell (Th1/Th2) function, to also include differences in neonatal regulatory T cell (Treg) and Th17 function, and moreover, that these pathways are also epigenetically regulated.

SUMMARY

New studies reinforce the importance of in-utero exposures (including dietary nutrients, microbial products, cigarette smoking, and certain maternal mediations) in fetal immune development and in programming the susceptibility to asthma and allergic disease.

Reproductive performance in East Greenland polar bears (Ursus maritimus) may be affected by organohalogen contaminants as shown by physiologically-based pharmacokinetic (PBPK) modelling

Polar bears (Ursus maritimus) feed mainly on ringed seal (Phoca hispida) and consume large quantities of blubber and consequently have one of the highest tissue concentrations of organohalogen contaminants (OHCs) worldwide. In East Greenland, studies of OHC time trends and organ system health effects, including reproductive, were conducted during 1990-2006. However, it has been difficult to determine the nature of the effects induced by OHC exposures on wild caught polar bears using body burden data and associated changes in reproductive organs and systems. We therefore conducted a risk quotient (RQ) evaluation to more quantitatively evaluate the effect risk on reproduction (embryotoxicity and teratogenicity) based on the critical body residue (CBR) concept and using a physiologically-based pharmacokinetic (PBPK) model. We applied modelling approaches to PCBs, p,p'-DDE, dieldrin, oxychlordane, HCHs, HCB, PBDEs and PFOS in East Greenland polar bears based on known OHC pharmacokinetics and dynamics in laboratory rats (Rattus rattus). The results showed that subcutaneous adipose tissue concentrations of dieldrin (range: 79-1271 ng g(-1) lw) and PCBs (range: 4128-53,923 ng g(-1) lw) reported in bears in the year 1990 were in the range to elicit possible adverse health effects on reproduction in polar bears in East Greenland (all RQs > or = 1). Similar results were found for PCBs (range: 1928-17,376 ng g(-1) lw) and PFOS (range: 104-2840 ng g(-1) ww) in the year 2000 and for dieldrin (range: 43-640 ng g(-1) lw), PCBs (range: 3491-13,243 ng g(-1) lw) and PFOS (range: 1332-6160 ng g(-1) ww) in the year 2006. The concentrations of oxychlordane, DDTs, HCB and HCHs in polar bears resulted in RQs<1 and thus appear less likely to be linked to reproductive effects. Furthermore, sumRQs above 1 suggested risk for OHC additive effects. Thus, previous suggestions of possible adverse health effects in polar bears correlated to OHC exposure are supported by the present study. This study also indicates that PBPK models may be a supportive tool in the evaluation of possible OHC-mediated health effects for Arctic wildlife.

Chronic dietary exposure to environmental organochlorine contaminants induces thyroid gland lesions in Arctic foxes (Vulpes lagopus)

The impact of dietary organochlorine (OC) exposure on thyroid gland pathology was studied in farmed male Arctic foxes (Vulpes lagopus). The exposed group (n=16) was fed a diet based on wild minke whale (Balaenoptera acutorostrata) blubber as a main fat source in order to mimic the exposure to OC cocktails in the Artic environment. This resulted in an exposure of approximately 17 microg Sigma OC/kg day and a Sigma OC residue adipose tissue and liver concentration of 1700 and 4470 ng/gl.w., respectively, after 16 months of exposure. Control foxes (n=13) were fed a diet with pork (Sus scrofa) fat as a main fat source containing significantly lower OC concentrations. The food composition fed to the control and exposed group was standardized for nutrient contents. Four OC-related histopathological changes were found: (1) flat-epithelial-cell true thyroid cysts (TC) characterized by neutral content; (2) remnants of simple squamous epithelial-cell embryonic ducts containing neutral debris (EDN); (3) remnants of stratified squamous epithelial-cell embryonic ducts containing acid mucins often accompanied with debris of leukocyte inflammatory nature (EDM) and (4) disseminated thyroid C-cell hyperplasia (HPC). Of these, the prevalence of TC, EDN and HPC was significantly highest in the exposed group (chi(2) test: all p<0.04). The study shows that the OC mixture in minke whale blubber may cause development of thyroid gland cysts, C-cell hyperplasia and increase the prevalence of cystic remnants of embryonic ducts. The mechanism causing these effects could include endocrine disruption of the hypothalamus-pituitary-thyroid (HPT) axis, a disturbance of the calcium homeostasis/metabolism or energy metabolism or immune suppression. Because concentrations of OCs are higher in wild Arctic foxes, it is likely that these animals could suffer from similar OC-induced thyroid gland pathological and functional changes.

Developmental immunotoxicology (DIT): windows of vulnerability, immune dysfunction and safety assessment

Developmental immunotoxicity (DIT) is an increasing health concern since DIT outcomes predispose children to those diseases that have been on the rise in recent decades (e.g., childhood asthma, allergic diseases, autoimmune conditions, childhood infections). The enhanced vulnerability of the developing immune system for environmental insult is based on unique immune maturational events that occur during critical windows of vulnerability in early life. The semi-allogeneic pregnancy state, with suppression of graft rejection and associated skewing of the fetal and neonatal immune system, also influences the specific nature of DIT outcomes. In the exposed offspring, targeted immunosuppression can co-exist with an increased risk of allergic and/or autoimmune disease. Because with DIT immune dysfunction rather than profound immunosuppression is the greater concern, testing approaches should emphasize multi-functional assessment. Beyond T-cells, dendritic cells and macrophages are sensitive targets. The last-trimester fetus and the neonate are normally depressed in T(H)1-dependent functions and postnatal acquisition of needed T(H)1 capacity is a major concern with DIT. With this in mind, assessment should include a measure of T(H)1-dependent cell-mediated immunity [cytotoxic T-lymphocyte (CTL) activity or delayed-type hypersensitivity (DTH) response] in conjunction with a multi-isotype T-dependent antibody response (TDAR) and evaluation of innate immunity (e.g., NK activity). Other parameters such as immune histology, immunophenotyping, cytokine responses, and organ weights can be useful when included with immune functional evaluation. A multifunctional DIT protocol using influenza challenge is presented as one example of an approach that permits dysfunction and misregulation to be evaluated.

Residential exposure to polychlorinated biphenyls and organochlorine pesticides and risk of childhood leukemia

BACKGROUND

Incidence of childhood leukemia in industrialized countries rose significantly during 1975-2004, and the reasons for the increase are not understood.

OBJECTIVES

We used carpet dust as an exposure indicator to examine the risk of childhood leukemia in relation to residential exposure to persistent organochlorine chemicals: six polychlorinated biphenyl (PCB) congeners and the pesticides alpha- and gamma-chlordane, p,p'-DDT (dichlorodiphenyltrichloroethane), p,p'-DDE (dichlorodiphenyldichloroethylene), methoxychlor, and pentachlorophenol.

METHODS

We conducted a population-based case-control study in 35 counties in northern and central California in 2001-2006. The study included 184 acute lymphocytic leukemia (ALL) cases 0-7 years of age and 212 birth certificate controls matched to cases by birth date, sex, race, and Hispanic ethnicity. We collected carpet dust samples from the room where the child spent the most time before diagnosis (similar date for controls) using a specialized vacuum.

RESULTS

Detection of any PCB congener in the dust conferred a 2-fold increased risk of ALL [odds ratio (OR) = 1.97; 95% confidence interval (CI), 1.22-3.17]. Compared with those in the lowest quartile of total PCBs, the highest quartile was associated with about a 3-fold risk (OR = 2.78; 95% CI, 1.41-5.48), and the positive trend was significant (p = 0.017). Significant positive trends in ALL risk were apparent with increasing concentrations of PCB congeners 118, 138, and 153. We observed no significant positive associations for chlordane, DDT, DDE, methoxychlor, or pentachlorophenol. The associations with PCBs were stronger among non-Hispanic whites than among Hispanics despite similar distributions of PCB levels among controls in each racial/ethnic group.

CONCLUSIONS

Our findings suggest that PCBs, which are considered probable human carcinogens and cause perturbations of the immune system, may represent a previously unrecognized risk factor for childhood leukemia.

Association between thyroid hormone levels and 4,4'-DDE concentrations in pregnant women (Valencia, Spain)

INTRODUCTION

Several epidemiological studies have reported that some organochlorine compounds (OCs), such as polychlorobiphenyls (PCBs) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), may alter thyroid function.

OBJECTIVE

The aim of the present study was to investigate the association of maternal serum OC concentrations of 4,4'-DDE and the sum of seven PCB congeners (PCB 28, 52, 101, 118, 138, 153, and 180) with thyroid hormone (TH) status.

METHODS

We measured OC concentrations in 157 maternal serum samples at 12 weeks of pregnancy in a cohort from Valencia (Spain). Thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), and free thyroxine (FT4) were measured as biomarkers of thyroid function in the same samples. Linear and logistic regression analyses were performed between OCs and TH levels, and variables were log transformed.

RESULTS

Mothers with higher levels of 4,4'-DDE had higher odds of having TSH levels >2.5 mIU/L (OR=2.53; 95% CI=1.36; 4.73; p=0.004), and we found a significant negative association between serum 4,4'-DDE concentrations and FT4 levels (beta=-0.03; 95% CI=-0.05; 0.00; p=0.050) after adjustment for covariates and total lipids. No association was found between sum of PCBs and TH levels.

CONCLUSION

Serum concentrations of 4,4'-DDE were associated with increased TSH and reduced FT4 but not TT3 levels. Our results suggest that some environmental chemicals may interfere with the thyroid system of pregnant women. The major role that maternal THs may play in fetal neurodevelopment makes these findings especially relevant.