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    ABSTRACT: This review focuses on how environmental factors through epigenetics modify disease risk and health outcomes. Major epigenetic events, such as histone modifications, DNA methylation, and microRNA expression, are described. The function of dose, duration, composition, and window of exposure in remodeling the individual's epigenetic terrain and disease susceptibility are addressed. The ideas of lifelong editing of early-life epigenetic memories, transgenerational effects through germline transmission, and the potential role of hydroxylmethylation of cytosine in developmental reprogramming are discussed. Finally, the epigenetic effects of several major classes of environmental factors are reviewed in the context of pathogenesis of disease. These include endocrine disruptors, tobacco smoke, polycyclic aromatic hydrocarbons, infectious pathogens, particulate matter, diesel exhaust particles, dust mites, fungi, heavy metals, and other indoor and outdoor pollutants. We conclude that the summation of epigenetic modifications induced by multiple environmental exposures, accumulated over time, represented as broad or narrow, acute or chronic, developmental or lifelong, may provide a more precise assessment of risk and consequences. Future investigations may focus on their use as readouts or biomarkers of the totality of past exposure for the prediction of future disease risk and the prescription of effective countermeasures.
    ILAR journal / National Research Council, Institute of Laboratory Animal Resources 12/2012; 53(3-4):289-305. DOI:10.1093/ilar.53.3-4.289 · 1.05 Impact Factor
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    ABSTRACT: There is increasing evidence that epigenetic regulation of gene expression plays a pivotal role in the orchestration of immune and allergic responses. Such regulatory mechanisms have potentially important implications for the acquisition of sensitization to chemical and drug allergens; and in determining the vigor, characteristics, and longevity of allergic responses. Importantly, the discovery of long-lasting epigenetic alterations in specific immunoregulatory genes provides a mechanistic basis for immune cell memory, and thereby the potential of chemical allergens to influence the subsequent orientation of the adaptive immune system. In this article, we consider the implications of epigenetic mechanisms for the development of sensitization to chemical and drug allergens and the form that allergic reactions will take.
    Toxicological Sciences 06/2012; 130(1):60-9. DOI:10.1093/toxsci/kfs207 · 4.48 Impact Factor
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    ABSTRACT: Recently, a genome wide association study (GWAS) conducted in Korean subjects identified three CTNNA3 (alpha-T catenin) single nucleotide polymorphisms (SNPs) (rs10762058, rs7088181, and rs4378283) associated with diisocyanate induced occupational asthma (DA). The CTNNA3 gene codes for a cadherin involved in formation of stretch-resistant cell-cell adhesions. We conducted a candidate gene association study to replicate these findings in Caucasian workers. Genotyping was performed on DNA using a 5' nuclease PCR assay collected from 410 diisocyanate exposed and predominantly Canadian workers including: 132 workers with DA confirmed by a specific inhalation challenge (DA+); 131 symptomatic workers in whom DA was excluded by a negative challenge (DA-); and 147 HDI-exposed asymptomatic workers (AWs). As in the Korean study, highly linked CTNNA3 rs7088181 and rs10762058 SNPs were significantly associated with DA+ when compared to AWs but not in comparison to DA- workers (p≤ 0.05). After adjusting for potentially confounding variables of age, smoking status and duration of exposure, minor allele homozygotes of rs7088181 and rs10762058 SNPs were at increased risk for DA compared with AWs [OR= 9.05 (95% CI:1.69, 48.54) and OR = 6.82 (95% CI:1.65, 28.24), respectively]. In conclusion, we replicated results from the only reported GWAS study of DA demonstrating an association between two closely linked CTNNA3 gene SNPs and DA. These findings lend further support to the clinical relevance of these genotypes in predicting susceptibility to DA and the potential importance of cadherins in the disease process.
    Toxicological Sciences 09/2012; 131(1). DOI:10.1093/toxsci/kfs272 · 4.48 Impact Factor

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