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2.  Diet and Asthma: Vitamins and Methyl Donors 
The lancet. Respiratory medicine  2013;1(10):813-822.
Dietary changes may partly explain the high burden of asthma in industrialized nations. Experimental studies have motivated a significant number of observational studies of the relation between vitamins (A, C, D, and E) or nutrients acting as methyl donors (folate, vitamin B12, and choline) and asthma. Because observational studies are susceptible to several sources of bias, well-conducted randomized controlled trials (RCTs) remain the “gold standard” to determine whether a vitamin or nutrient has an effect on asthma. Evidence from observational studies and/or relatively few RCTs most strongly justify ongoing and future RCTs of: 1) vitamin D to prevent or treat asthma, 2) choline supplementation as adjuvant treatment for asthma, and 3) vitamin E to prevent the detrimental effects of air pollution in subjects with asthma. At this time, there is insufficient evidence to recommend supplementation with any vitamin or nutrient acting as a methyl donor to prevent or treat asthma.
PMCID: PMC3904132  PMID: 24461761
3.  Diagnostic accuracy of the bronchodilator response in children 
The bronchodilator response (BDR) reflects the reversibility of airflow obstruction and is recommended as an adjunctive test to diagnose asthma. The validity of the commonly used definition of BDR, a 12% or greater change in FEV1 from baseline, has been questioned in childhood.
We sought to examine the diagnostic accuracy of the BDR test by using 3 large pediatric cohorts.
Cases include 1041 children with mild-to-moderate asthma from the Childhood Asthma Management Program.
Control subjects (nonasthmatic and nonwheezing) were chosen from Project Viva and Home Allergens, 2 population-based pediatric cohorts. Receiver operating characteristic curves were constructed, and areas under the curve were calculated for different BDR cutoffs.
A total of 1041 cases (59.7% male; mean age, 8.9 ± 2.1 years) and 250 control subjects (46.8% male; mean age, 8.7 ± 1.7 years) were analyzed, with mean BDRs of 10.7% ± 10.2% and 2.7% ± 8.4%, respectively. The BDR test differentiated asthmatic patients from nonasthmatic patients with a moderate accuracy (area under the curve, 73.3%).
Despite good specificity, a cutoff of 12% was associated with poor sensitivity (35.6%). A cutoff of less than 8% performed significantly better than a cutoff of 12% (P = .03, 8% vs 12%).
Our findings highlight the poor sensitivity associated with the commonly used 12% cutoff for BDR. Although our data show that a threshold of less than 8% performs better than 12%, given the variability of this test in children, we conclude that it might be not be appropriate to choose a specific BDR cutoff as a criterion for the diagnosis of asthma.
PMCID: PMC3759549  PMID: 23683464
Asthma; bronchodilator response; diagnosis
4.  A genome-wide association study of bronchodilator response in asthmatics 
The pharmacogenomics journal  2013;14(1):41-47.
Reversibility of airway obstruction in response to β2-agonists is highly variable among asthmatics, which is partially attributed to genetic factors. In a genome-wide association study of acute bronchodilator response (BDR) to inhaled albuterol, 534,290 single nucleotide polymorphisms (SNPs) were tested in 403 white trios from the Childhood Asthma Management Program using five statistical models to determine the most robust genetic associations. The primary replication phase included 1397 polymorphisms in three asthma trials (pooled n=764). The second replication phase tested 13 SNPs in three additional asthma populations (n=241, n=215, and n=592). An intergenic SNP on chromosome 10, rs11252394, proximal to several excellent biological candidates, significantly replicated (p=1.98×10−7) in the primary replication trials. An intronic SNP (rs6988229) in the collagen (COL22A1) locus also provided strong replication signals (p=8.51×10−6). This study applied a robust approach for testing the genetic basis of BDR and identified novel loci associated with this drug response in asthmatics.
PMCID: PMC3706515  PMID: 23508266
pharmacogenetics; asthma; bronchodilator response; genome-wide association study; albuterol
5.  Epigenetic Influences on Associations between Air Pollutants and Lung Function in Elderly Men: The Normative Aging Study 
Environmental Health Perspectives  2014;122(6):566-572.
Background: Few studies have been performed on pulmonary effects of air pollution in the elderly—a vulnerable population with low reserve capacity—and mechanisms and susceptibility factors for potential effects are unclear.
Objectives: We evaluated the lag structure of air pollutant associations with lung function and potential effect modification by DNA methylation (< or ≥ median) at 26 individual CpG sites in nine candidate genes in a well-characterized cohort of elderly men.
Methods: We measured forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and blood DNA methylation one to four times between 1999 and 2009 in 776 men from the Normative Aging Study. Air pollution was measured at fixed monitors 4 hr to 28 days before lung function tests. We used linear mixed-effects models to estimate the main effects of air pollutants and effect modification by DNA methylation.
Results: An interquartile range (IQR) increase in subchronic exposure (3 to 28 days cumulated), but not in acute exposure (during the previous 4 hr, or the current or previous day), to black carbon, total and nontraffic particles with aerodynamic diameter ≤ 2.5 μm (PM2.5), carbon monoxide, and nitrogen dioxide was associated with a 1–5% decrease in FVC and FEV1 (p < 0.05). Slope estimates were greater for FVC than FEV1, and increased with cumulative exposure. The estimates slopes for air pollutants (28 days cumulated) were higher in participants with low (< median) methylation in TLR2 at position 2 and position 5 and high (≥ median) methylation in GCR.
Conclusions: Subchronic exposure to traffic-related pollutants was associated with significantly reduced lung function in the elderly; nontraffic pollutants (particles, ozone) had weaker associations. Epigenetic mechanisms related to inflammation and immunity may influence these associations.
Citation: Lepeule J, Bind MAC, Baccarelli AA, Koutrakis P, Tarantini L, Litonjua A, Sparrow D, Vokonas P, Schwartz JD. 2014. Epigenetic influences on associations between air pollutants and lung function in elderly men: the Normative Aging Study. Environ Health Perspect 122:566–572;
PMCID: PMC4050500  PMID: 24602767
6.  Dissecting direct and indirect genetic effects on chronic obstructive pulmonary disease (COPD) susceptibility 
Human genetics  2013;132(4):431-441.
Cigarette smoking is the major environmental risk factor for chronic obstructive pulmonary disease (COPD). Genome-wide association studies have provided compelling associations for three loci with COPD. In this study, we aimed to estimate direct, i.e., independent from smoking, and indirect effects of those loci on COPD development using mediation analysis. We included a total of 3,424 COPD cases and 1,872 unaffected controls with data on two smoking-related phenotypes: lifetime average smoking intensity and cumulative exposure to tobacco smoke (pack years). Our analysis revealed that effects of two linked variants (rs1051730 and rs8034191) in the AGPHD1/CHRNA3 cluster on COPD development are significantly, yet not entirely, mediated by the smoking-related phenotypes. Approximately 30 % of the total effect of variants in the AGPHD1/CHRNA3 cluster on COPD development was mediated by pack years. Simultaneous analysis of modestly (r2 = 0.21) linked markers in CHRNA3 and IREB2 revealed that an even larger (~42 %) proportion of the total effect of the CHRNA3 locus on COPD was mediated by pack years after adjustment for an IREB2 single nucleotide polymorphism. This study confirms the existence of direct effects of the AGPHD1/CHRNA3, IREB2, FAM13A and HHIP loci on COPD development. While the association of the AGPHD1/CHRNA3 locus with COPD is significantly mediated by smoking-related phenotypes, IREB2 appears to affect COPD independently of smoking.
PMCID: PMC3600068  PMID: 23299987
7.  Allergen sensitization is associated with increased DNA methylation in older men 
Variation in epigenetic modifications, arising from either environmental exposures or internal physiological changes, can influence gene expression, and may ultimately contribute to complex diseases such as asthma and allergies. We examined the association of asthma and allergic phenotypes with DNA methylation levels of retrotransposon-derived elements.
We used data from 704 men (mean age 73) in the longitudinal Normative Aging Study to assess the relationship between asthma, allergic phenotypes and DNA methylation levels of the retrotransposon derived elements Alu and LINE-1. Retrotransposons represent a large fraction of the genome (> 30%), and are heavily methylated to prevent expression. Percent methylation of Alu and LINE-1 elements in peripheral white blood cells was quantified using PCR pyrosequencing. Data on sensitization to common allergens by skin prick testing, asthma, and methacholine responsiveness was gathered approximately 8 years prior to DNA methylation analysis.
Prior allergen sensitization was associated with increased methylation of Alu (β=0.32 [sensitized vs. non-sensitized], p value 0.003), in models adjusted for pack-years, BMI, smoking, air pollutants, percent eosinophils, white blood cell count and age. Of the men interviewed, 5 % of subjects reported diagnosis of asthma. Neither Alu, nor LINE-1 methylation was associated with asthma.
These data suggest that increased DNA methylation of repetitive elements may be associated with allergen sensitization, but does not appear to be associated with asthma. Future work is needed to identify potential underlying mechanisms for these relationships.
PMCID: PMC3730837  PMID: 23257623
allergen sensitization; DNA methylation; Alu; and LINE-1
8.  Genome-Wide Association Analysis of Blood Biomarkers in Chronic Obstructive Pulmonary Disease 
Rationale: A genome-wide association study (GWAS) for circulating chronic obstructive pulmonary disease (COPD) biomarkers could identify genetic determinants of biomarker levels and COPD susceptibility.
Objectives: To identify genetic variants of circulating protein biomarkers and novel genetic determinants of COPD.
Methods: GWAS was performed for two pneumoproteins, Clara cell secretory protein (CC16) and surfactant protein D (SP-D), and five systemic inflammatory markers (C-reactive protein, fibrinogen, IL-6, IL-8, and tumor necrosis factor-α) in 1,951 subjects with COPD. For genome-wide significant single nucleotide polymorphisms (SNPs) (P < 1 × 10−8), association with COPD susceptibility was tested in 2,939 cases with COPD and 1,380 smoking control subjects. The association of candidate SNPs with mRNA expression in induced sputum was also elucidated.
Measurements and Main Results: Genome-wide significant susceptibility loci affecting biomarker levels were found only for the two pneumoproteins. Two discrete loci affecting CC16, one region near the CC16 coding gene (SCGB1A1) on chromosome 11 and another locus approximately 25 Mb away from SCGB1A1, were identified, whereas multiple SNPs on chromosomes 6 and 16, in addition to SNPs near SFTPD, had genome-wide significant associations with SP-D levels. Several SNPs affecting circulating CC16 levels were significantly associated with sputum mRNA expression of SCGB1A1 (P = 0.009–0.03). Several SNPs highly associated with CC16 or SP-D levels were nominally associated with COPD in a collaborative GWAS (P = 0.001–0.049), although these COPD associations were not replicated in two additional cohorts.
Conclusions: Distant genetic loci and biomarker-coding genes affect circulating levels of COPD-related pneumoproteins. A subset of these protein quantitative trait loci may influence their gene expression in the lung and/or COPD susceptibility.
Clinical trial registered with (NCT 00292552).
PMCID: PMC3622441  PMID: 23144326
biomarker; chronic obstructive pulmonary disease; genome-wide association study
9.  Nitric oxide synthase polymorphisms, gene expression and lung function in chronic obstructive pulmonary disease 
Due to the pleiotropic effects of nitric oxide (NO) within the lungs, it is likely that NO is a significant factor in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of this study was to test for association between single nucleotide polymorphisms (SNPs) in three NO synthase (NOS) genes and lung function, as well as to examine gene expression and protein levels in relation to the genetic variation.
One SNP in each NOS gene (neuronal NOS (NOS1), inducible NOS (NOS2), and endothelial NOS (NOS3)) was genotyped in the Lung Health Study (LHS) and correlated with lung function. One SNP (rs1800779) was also analyzed for association with COPD and lung function in four COPD case–control populations. Lung tissue expression of NOS3 mRNA and protein was tested in individuals of known genotype for rs1800779. Immunohistochemistry of lung tissue was used to localize NOS3 expression.
For the NOS3 rs1800779 SNP, the baseline forced expiratory volume in one second in the LHS was significantly higher in the combined AG + GG genotypic groups compared with the AA genotypic group. Gene expression and protein levels in lung tissue were significantly lower in subjects with the AG + GG genotypes than in AA subjects. NOS3 protein was expressed in the airway epithelium and subjects with the AA genotype demonstrated higher NOS3 expression compared with AG and GG individuals. However, we were not able to replicate the associations with COPD or lung function in the other COPD study groups.
Variants in the NOS genes were not associated with lung function or COPD status. However, the G allele of rs1800779 resulted in a decrease of NOS3 gene expression and protein levels and this has implications for the numerous disease states that have been associated with this polymorphism.
PMCID: PMC3827989  PMID: 24192154
Chronic obstructive pulmonary disease; Nitric oxide synthase; Polymorphism; Gene expression
10.  A polymorphism in the thyroid hormone receptor gene is associated with bronchodilator response in asthmatics 
The pharmacogenomics journal  2012;13(2):130-136.
A pro-asthmatic culture milieu and β2-agonist (isoproterenol) were previously shown to regulate the expression of select transcription factors (TFs) within human airway epithelial and smooth muscle cells. This study tests 1116 single nucleotide polymorphisms (SNPs) across 98 of these TF genes for association with bronchodilator response (BDR) in asthma patients. Genotyping was conducted using the Illumina HumanHap550v3 Beadchip in 403 non-Hispanic White asthmatic children and their parents. SNPs were evaluated for association with BDR using family and population-based analyses. Forty-two SNPs providing p values < 0.1 in both analyses were then genotyped in three adult asthma trials. One SNP 5’ of the thyroid hormone receptor beta gene was associated with BDR in the childhood population and two adult populations (p value = 0.0012). This investigation identified a novel locus for inter-individual variability in BDR and represents a translation of a cellular drug-response study to potential personalization of clinical asthma management.
PMCID: PMC3349771  PMID: 22212731
Bronchodilator response; transcription factor; association; thyroid hormone receptor β; asthma; pharmacogenetics
11.  Vitamin D Deficiency, Smoking, and Lung Function in the Normative Aging Study 
Rationale: Vitamin D has immunomodulatory and antiinflammatory effects that may be modified by cigarette smoke and may affect lung function.
Objectives: To examine the effect of vitamin D deficiency and smoking on lung function and lung function decline.
Methods: A total of 626 men from the Normative Aging Study had 25-hydroxyvitamin D levels measured at three different times between 1984 and 2003 with concurrent spirometry. Vitamin D deficiency was defined as serum level ≤ 20 ng/ml. Statistical analysis was performed using multivariable linear regression and mixed effects models.
Measurements and Main Results: In the overall cohort, there was no significant effect of vitamin D deficiency on lung function or on lung function decline. In both cross-sectional and longitudinal multivariable models, there was effect modification by vitamin D status on the association between smoking and lung function. Cross-sectional analysis revealed lower lung function in current smokers with vitamin D deficiency (FEV1, FVC, and FEV1/FVC; P ≤ 0.0002), and longitudinal analysis showed more rapid rates of decline in FEV1 (P = 0.023) per pack-year of smoking in subjects with vitamin D deficiency as compared with subjects who were vitamin D sufficient.
Conclusions: Vitamin D deficiency was associated with lower lung function and more rapid lung function decline in smokers over 20 years in this longitudinal cohort of elderly men. This suggests that vitamin D sufficiency may have a protective effect against the damaging effects of smoking on lung function. Future studies should seek to confirm this finding in the context of smoking and other exposures that affect lung function.
PMCID: PMC3480523  PMID: 22822023
vitamin D; vitamin D deficiency; lung function decline; smoking; effect modification
12.  Very important pharmacogene summary for VDR 
Pharmacogenetics and genomics  2012;22(10):758-763.
PMCID: PMC3678550  PMID: 22588316
drug response; genetic variants; pharmacogenomics; vitamin D receptor
13.  Effect of Vitamin D and Inhaled Corticosteroid Treatment on Lung Function in Children 
Rationale: Low vitamin D levels are associated with asthma and decreased airway responsiveness. Treatment with inhaled corticosteroids improves airway responsiveness and asthma control.
Objectives: To assess the effect of vitamin D levels on prebronchodilator FEV1, bronchodilator response, and responsiveness to methacholine (PC20, provocative concentration of methacholine producing a 20% decline in FEV1) in patients with asthma treated with inhaled corticosteroids.
Methods: We measured 25-hydroxyvitamin D levels in the serum of children with persistent asthma at the time of enrollment in the Childhood Asthma Management Program. We divided subjects into the vitamin D sufficiency (>30 ng/ml), insufficiency (20–30 ng/ml), and deficiency (<20 ng/ml) groups. Covariates included age, treatment, sex, body mass index, race, history of emergency department visits, hospitalizations, and season that vitamin D specimen was drawn. Our main outcome measures were change in prebronchodilator FEV1, bronchodilator response, and PC20 from enrollment to 8–12 months.
Measurements and Main Results: Of the 1,024 subjects, 663 (65%) were vitamin D sufficient, 260 (25%) were insufficient, and 101 (10%) were deficient. Vitamin D–deficient subjects were more likely to be older, African American, and have a higher body mass index compared with the vitamin D–sufficient and insufficient subjects. In the inhaled corticosteroid treatment group, prebronchodilator FEV1 increased from randomization to 12 months by 140 ml in the vitamin D–deficient group and prebronchodilator FEV1 increased by 330 ml in the vitamin D insufficiency group and by 290 ml in the vitamin D sufficiency group (P = 0.0072), in adjusted models.
Conclusions: In children with asthma treated with inhaled corticosteroids, vitamin D deficiency is associated with poorer lung function than in children with vitamin D insufficiency or sufficiency.
PMCID: PMC3480528  PMID: 22798322
asthma; vitamin D; lung function; forced expiratory volume; children
14.  Vitamin D Deficiency in Pregnancy and Gestational Diabetes 
We examined the association of second trimester maternal plasma 25-hydroxyvitamin D (25[OH]D) during pregnancy with gestational diabetes mellitus(GDM).
Study Design
Among 1314 pregnant women participating in Project Viva, a birth cohort study, we measured 25(OH)D levels at 26–28 weeks’ gestation during GDM screening using a 1-hour 50g glucose challenge test.
We found 25(OH)D levels <25nmol/L in 44/1087(4.0%) women with normal glucose tolerance, 9/159(5.7%) women with impaired glucose tolerance and 9/68(13.2%) women with GDM. Analyses adjusted for sociodemographics, season, maternal BMI, gestational weight gain and dietary factors, suggested that women with 25(OH)D levels <25 vs. ≥25 nmol/L may have higher odds of GDM (2.2 [0.8, 5.5]). Glucose levels after the glucose challenge test were inversely associated with 25(OH)D levels(P <0.01).
Second trimester 25(OH)D levels were inversely associated with glucose levels after 1-hour 50g glucose challenge test and low 25(OH)D levels may be associated with increased risk of GDM.
PMCID: PMC3432741  PMID: 22717271
Vitamin D; Gestational Diabetes Mellitus; 25-hydroxyvitamin D; GDM; pregnancy
15.  Genome-wide association analysis of circulating vitamin D levels in children with asthma 
Human genetics  2012;131(9):1495-1505.
Vitamin D deficiency is becoming more apparent in many populations. Genetic factors may play a role in the maintenance of vitamin D levels. The objective of this study was to perform a genome-wide analysis (GWAS) of vitamin D levels, including replication of prior GWAS results. We measured 25-hydroxyvitamin D (25(OH)D) levels in serum collected at the time of enrollment and at year 4 in 572 Caucasian children with asthma, who were part of a multi-center clinical trial, the Childhood Asthma Management Program. Replication was performed in a second cohort of 592 asthmatics from Costa Rica and a third cohort of 516 Puerto Rican asthmatics. In addition, we attempted replication of three SNPs that were previously identified in a large GWAS of Caucasian individuals. The setting included data from a clinical trial of childhood asthmatics and two cohorts of asthmatics recruited for genetic studies of asthma. The main outcome measure was circulating 25(OH)D levels. The 25(OH)D levels at the two time-points were only modestly correlated with each other (intraclass correlation coefficient = 0.33) in the CAMP population. We identified SNPs that were nominally associated with 25(OH)D levels at two time-points in CAMP, and replicated four SNPs in the Costa Rican cohort: rs11002969, rs163221, rs1678849, and rs4864976. However, these SNPs were not significantly associated with 25(OH)D levels in a third population of Puerto Rican asthmatics. We were able to replicate the SNP with the strongest effect, previously reported in a large GWAS: rs2282679 (GC), and we were able to replicate another SNP, rs10741657 (CYP2R1), to a lesser degree. We were able to replicate two of three prior significant findings in a GWAS of 25(OH)D levels. Other SNPs may be additionally associated with 25(OH)D levels in certain populations.
PMCID: PMC3648789  PMID: 22673963
16.  Forced Expiratory Volume in 1 Second and Cognitive Aging in Men 
To evaluate forced expiratory volume in 1 second (FEV1, a measure of overall lung function), long-term average FEV1, and rate of decline in FEV1 in relation to cognition and cognitive decline in older men.
Prospective observational study.
Community-based population.
Eight hundred sixty-four older men from the Normative Aging Study.
Starting in 1984, participants underwent triennial clinical evaluations. Lung function assessments provided estimates of FEV1. Cognitive assessments entailing tests of several cognitive abilities began in 1993. FEV1 measured approximately 12 years before baseline cognitive testing, average FEV1 over the 12-year period, and rate of change in FEV1 were all evaluated in relation to baseline and change in performance on the cognitive tests.
In multivariable-adjusted analyses, associations between FEV1 and baseline cognitive scores were mixed, although average FEV1 predicted significantly better performance on tests of visuospatial ability (P =.04) and general cognition (P =.03). Higher FEV1 was more consistently associated with slower cognitive decline, but only the association between historical FEV1 and attention was significant (difference per standard deviation in FEV1 = 0.056, P =.05). Rate of FEV1 decline was not consistently associated with cognitive function or decline. Findings were generally similar or stronger in men who had never smoked. To account for potential bias due to selective attrition, inverse probability of censoring weights were applied to the cognitive decline analyses, yielding slightly larger estimates; the inadequate prognostic power of the censoring models limited this approach.
Overall, the data provide limited evidence of an inverse association between FEV1 and cognitive aging.
PMCID: PMC3758858  PMID: 21718272
lung function; cognition; cognitive decline; epidemiology; aging
17.  Repetitive element hypomethylation in blood leukocyte DNA and cancer incidence, prevalence and mortality in elderly individuals: the Normative Aging Study 
Cancer causes & control : CCC  2010;22(3):437-447.
Global genomic hypomethylation is a common epigenetic event in cancer that mostly results from hypomethylation of repetitive DNA elements. Case-control studies have associated blood leukocyte DNA hypomethylation with several cancers. Because samples in case-control studies are collected after disease development, whether DNA hypomethylation is causal or just associated with cancer development is still unclear.
In 722 elderly subjects from the Normative Aging Study cohort, we examined whether DNA methylation in repetitive elements (Alu, LINE-1) was associated with cancer incidence (30 new cases, median follow-up: 89 months), prevalence (205 baseline cases), and mortality (28 deaths, median follow-up: 85 months). DNA methylation was measured by bisulfite pyrosequencing.
Individuals with low LINE-1 methylation (
These findings suggest that individuals with lower repetitive element methylation are at high risk of developing and dying from cancer.
PMCID: PMC3752839  PMID: 21188491
Repetitive elements; DNA methylation; Epigenetics; Blood; Cancer risk
There has been no longitudinal study of the relation between concurrent exposure to dust mite allergen and endotoxin in early life and asthma and atopy at school age.
To examine the relation between exposure to dust mite allergen and endotoxin at age 2 to 3 months and asthma, wheeze, and atopy in high-risk children.
Birth cohort study of 440 children with parental history of atopy in the Boston metropolitan area.
In multivariate analyses, early exposure to high levels of dust mite allergen (≥10 μg/g) was associated with increased risks of asthma at age 7 years (odds ratio [OR], 3.0; 95% CI, 1.1-7.9) and late-onset wheeze (OR, 5.0; 95% CI, 1.5-16.4). Exposure to endotoxin levels above the lowest quartile at age 2 to 3 months was associated with reduced odds of atopy at school age (OR, 0.5; 95% CI, 0.2-0.9). In contrast with its inverse association with atopy, endotoxin exposure in early life was associated with an increased risk of any wheeze between ages 1 and 7 years that did not change significantly with time (hazard ratio for each quartile increment in endotoxin levels, 1.23; 95% CI, 1.07-1.43).
Among children at risk of atopy, early exposure to high levels of dust mite allergen is associated with increased risks of asthma and late-onset wheeze. In these children, endotoxin exposure is associated with a reduced risk of atopy but an increased risk of wheeze.
Clinical implications
Early endotoxin exposure may be a protective factor against atopy but a risk factor for wheeze in high-risk children.
PMCID: PMC3737770  PMID: 17507083
Endotoxin; dust mite; wheeze; atopy; asthma
Annals of Epidemiology  2012;22(8):581-586.
In a prospective prenatal cohort study, we examined associations of second trimester and cord plasma 25-hydroxyvitamin D (25[OH]D) with small-for-gestational age (SGA), and the extent to which vitamin D might explain black/white differences in SGA.
We studied 1067 white and 236 black mother-infant pairs recruited from 8 obstetrical offices early in pregnancy in Massachusetts. We analyzed 25(OH)D levels using an immunoassay and performed multivariable logistic models to estimate the odds of SGA by category of 25(OH)D level.
Mean (standard deviation [SD]) second trimester 25(OH)D level was 60 nmol/L (21) and was lower for black (46 nmol/L [22]) than white (62 nmol/L [20]) women. 59 infants were SGA (4.5%) and more black than white infants were SGA (8.5% vs. 3.7%). The odds of SGA were higher with maternal 25(OH)D levels <25 vs. ≥25 nmol/L (adjusted odds ratio [OR] 3.17; 95% confidence interval [CI]:1.16, 8.63). The increased odds of SGA among black vs. white participants decreased from an OR of 2.04(1.04, 4.04) to 1.68(0.82, 3.46) after adjusting for 25(OH)D.
Second trimester 25(OH)D levels <25 nmol/L were associated with higher odds of SGA. Our data raise the possibility that Vitamin D status may contribute to racial disparities in SGA.
PMCID: PMC3396717  PMID: 22658824
Vitamin D; Infant; Small for Gestational Age; African Continental Ancestry Group; Health Status Disparities; Pregnancy
Experimental animal data on the gram-negative bacterial biomarker endotoxin suggest that persistence, dose and timing of exposure are likely to influence its effects on allergy and wheeze. In epidemiologic studies, endotoxin may be a sentinel marker for a microbial milieu, including gram-positive as well as gram-negative bacteria, that may influence allergy and asthma through components (pathogen-associated molecular patterns) that signal through innate Toll-like receptor pathways.
To determine the influence of current gram-negative and gram-positive bacterial exposures on asthma and allergic sensitization in school-aged children.
We examined the relationship between bacterial biomarkers and current asthma and allergic sensitization in 377 school-aged children in a birth-cohort study. We then evaluated the effects of school-age endotoxin, after controlling for exposure in early life.
Exposure to gram-negative bacteria was inversely associated with asthma and allergic sensitization at school-age (for > median endotoxin: prevalence odds ratio [POR] =0.34 [95% CI=0.2 to 0.7] for current asthma and prevalence ratio [PR]=0.77 [95% CI=0.6 to 0.97] for allergic sensitization). In contrast, elevated gram-positive bacteria in the bed was inversely associated with current asthma (POR= 0.41, 95% CI=0.2 to 0.9) but not with allergic sensitization (POR=1.07, 95% CI=0.8 to 1.4). School-age endotoxin exposure remained protective in models for allergic disease adjusted for early-life endotoxin.
Both gram-negative and gram-positive bacterial exposures are associated with decreased asthma symptoms, but may act through different mechanisms to confer protection. Endotoxin exposure in later childhood is not simply a surrogate of early life exposure; it has independent protective effects on allergic disease.
PMCID: PMC3730840  PMID: 20412140
childhood asthma; allergic sensitization; endotoxin; peptidoglycan
Rationale: Vitamin D insufficiency (a serum 25(OH)D <30 ng/ml) has been associated with severe asthma exacerbations, but this could be explained by underlying racial ancestry or disease severity. Little is known about vitamin D and asthma in Puerto Ricans.
Objectives: To examine whether vitamin D insufficiency is associated with severe asthma exacerbations in Puerto Rican children, independently of racial ancestry, atopy, and time outdoors.
Methods: A cross-sectional study was conducted of 560 children ages 6–14 years with (n = 287) and without (n = 273) asthma in San Juan, Puerto Rico. We measured plasma vitamin D and estimated the percentage of African racial ancestry among participants using genome-wide genotypic data. We tested whether vitamin D insufficiency is associated with severe asthma exacerbations, lung function, or atopy (greater than or equal to one positive IgE to allergens) using logistic or linear regression. Multivariate models were adjusted for African ancestry, time outdoors, atopy, and other covariates.
Measurements and Main Results: Vitamin D insufficiency was common in children with (44%) and without (47%) asthma. In multivariate analyses, vitamin D insufficiency was associated with higher odds of greater than or equal to one severe asthma exacerbation in the prior year (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.5–4.9; P = 0.001) and atopy, and a lower FEV1/FVC in cases. After stratification by atopy, the magnitude of the association between vitamin D insufficiency and severe exacerbations was greater in nonatopic (OR, 6.2; 95% CI, 2–21.6; P = 0.002) than in atopic (OR, 2; 95% CI, 1–4.1; P = 0.04) cases.
Conclusions: Vitamin D insufficiency is associated with severe asthma exacerbations in Puerto Rican children, independently of racial ancestry, atopy, or markers of disease severity or control.
PMCID: PMC3406083  PMID: 22652028
vitamin D; asthma exacerbations; Puerto Ricans; childhood
The adverse effects of corticosteroids on bone mineral accretion (BMA) have been well documented. Vitamin D insufficiency, a prevalent condition in the pediatric population, has also been associated with decreased bone mineral density (BMD).
To determine whether children with asthma who have lower vitamin D levels are more susceptible to the negative effects of corticosteroids on BMD over time.
Children aged 5–12 years with mild-to-moderate asthma who participated in the Childhood Asthma Management Program were followed for a mean of 4.3 years. Total doses of inhaled and oral corticosteroids (OCS) were recorded, serum 25-hydroxyvitamin D3 levels were measured at the beginning of the trial and serial DEXA scans of the lumbar spine were performed. Annual BMA rates were defined as: [(BMD at 4 years follow-up − BMD at baseline)/4 years].
BMA was calculated for 780 subjects. In boys, baseline vitamin D levels significantly modified the relationship between OCS and BMA (vitamin D x OCS interaction, p=0.023). Stratification by vitamin D levels showed a decrease in BMA with increased use of OCS in vitamin D insufficient boys only (p<0.001). Compared to vitamin D sufficient boys, vitamin D insufficient boys exposed to more than 2 courses of oral corticosteroids per year had twice the decrease in BMA rate (relative to boys who were OCS-unexposed).
Vitamin D levels significantly modified the effect of oral corticosteroids on bone mineral accretion in boys. Further research is needed to examine whether vitamin D supplementation in children with poorly controlled asthma may confer benefits to bone health.
PMCID: PMC3387323  PMID: 22608570
Asthma; vitamin D; bone mineral density; corticosteroids
Epidemiology (Cambridge, Mass.)  2010;21(6):819-828.
Epigenetic features such as DNA hypomethylation have been associated with conditions related to cardiovascular risk. We evaluated whether lower blood DNA methylation in heavily methylated repetitive sequences predicts the risk of ischemic heart disease and stroke.
We quantified blood DNA methylation of LINE-1 repetitive elements through PCR-pyrosequencing in 712 elderly individuals from the Boston-area Normative Aging Study. We estimated risk-factor adjusted relative risks (RRs) for ischemic heart disease and stroke at baseline (242 prevalent cases); as well as in incidence (44 new cases; median follow-up, 63 months); and subsequent mortality from ischemic heart disease (86 deaths; median follow-up, 75 months).
Blood LINE-1 hypomethylation was associated with baseline ischemic heart disease (RR=2.1 [95% confidence interval = 1.2 to 4.0] for lowest vs. highest methylation quartile) and for stroke (2.5 [0.9 to 7.5]). Among participants free of baseline disease, individuals with methylation below the median also had higher risk of developing ischemic heart disease (4.0 [1.8 to 8.9]) or stroke (5.7 [0.8 to 39.5]). In the entire cohort, persons with methylation below the median had higher mortality from ischemic heart disease (3.3 [1.3 to 8.4]) and stroke (2.8 [0.6 to 14.3]). Total mortality was also increased (2.0 [1.2 to 3.3]). These results were confirmed in additional regression models using LINE-1 methylation as a continuous variable.
Subjects with prevalent IHD and stroke exhibited lower LINE-1 methylation. In longitudinal analyses, persons with lower LINE-1 methylation were at higher risk for incident ischemic heart disease and stroke, and for total mortality.
PMCID: PMC3690659  PMID: 20805753
The innate immune pathway is important in the pathogenesis of asthma and eczema. However, only a few variants in these genes have been associated with either disease. We investigate the association between polymorphisms of genes in the innate immune pathway with childhood asthma and eczema. In addition, we compare individual associations with those discovered using a multivariate approach.
Using a novel method, case control based association testing (C2BAT), 569 single nucleotide polymorphisms (SNPs) in 44 innate immune genes were tested for association with asthma and eczema in children from the Boston Home Allergens and Asthma Study and the Connecticut Childhood Asthma Study. The screening algorithm was used to identify the top SNPs associated with asthma and eczema. We next investigated the interaction of innate immune variants with asthma and eczema risk using Bayesian networks.
After correction for multiple comparisons, 7 SNPs in 6 genes (CARD25, TGFB1, LY96, ACAA1, DEFB1, and IFNG) were associated with asthma (adjusted p-value<0.02), while 5 SNPs in 3 different genes (CD80, STAT4, and IRAKI) were significantly associated with eczema (adjusted p-value < 0.02). None of these SNPs were associated with both asthma and eczema. Bayesian network analysis identified 4 SNPs that were predictive of asthma and 10 SNPs that predicted eczema. Of the genes identified using Bayesian networks, only CD80 was associated with eczema in the single-SNP study. Using novel methodology that allows for screening and replication in the same population, we have identified associations of innate immune genes with asthma and eczema. Bayesian network analysis suggests that additional SNPs influence disease susceptibility via SNP interactions.
Our findings suggest that innate immune genes contribute to the pathogenesis of asthma and eczema, and that these diseases likely have different genetic determinants.
PMCID: PMC3412627  PMID: 22192168
asthma; Bayesian network; genetic association; eczema; innate immunity
Puerto Ricans and African Americans share a significant proportion of African ancestry. Recent findings suggest that African ancestry influences lung function in African American adults.
To examine whether a greater proportion of African ancestry is associated with lower FEV1 and FVC in Puerto Rican children, independently of socioeconomic status (SES), healthcare access or key environmental/lifestyle (EL) factors.
Cross-sectional case-control study of 943 Puerto Rican children ages 6 to 14 years with (n=520) and without (n=423) asthma (defined as physician-diagnosed asthma and wheeze in the prior year) living in Hartford (CT, n=383) and San Juan (PR, n=560). We estimated the percentage of African racial ancestry in study participants using genome-wide genotypic data. We tested whether African ancestry is associated with FEV1 and FVC using linear regression. Multivariate models were adjusted for indicators of SES and healthcare, and selected EL exposures.
After adjustment for household income and other covariates, each 20% increment in African ancestry was significantly associated with lower pre-bronchodilator(BD) FEV1 (−105 ml, 95% confidence interval [CI] = −159 ml to −51 ml, P <0.001) and FVC (−133 ml, 95% CI −197 ml to −69 ml, P <0.001), and post-BD FEV1 (−152 ml, 95% CI=−210 ml to −94 ml, P <0.001) and FVC (−145 ml, 95% CI= −211 to −79 ml, P <0.001) in children with asthma. Similar but weaker associations were found for pre- and post-BD FEV1 (change for each 20% increment in African ancestry= −78 ml, 95% CI= −131 to −25 ml, P=0.004), and for post-BD FVC among children without asthma.
Genetic and/or EL factors correlated with African ancestry may influence childhood lung function in Puerto Ricans.
PMCID: PMC3367038  PMID: 22560959
ancestry; FEV1; FVC; Puerto Ricans; childhood

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