Relationships among environmental exposures, cord blood cytokine responses, allergy, and wheeze at 1 year of age in an inner-city birth cohort (Urban Environment and Childhood Asthma study)

Abstract

Background: The Urban Environment and Childhood Asthma study was established to investigate the immunologic and environmental causes of asthma in inner-city children.

Objective: We sought to evaluate potential atopic outcomes in the first 12 months and their relationships to environmental exposures and immune development.

Methods: A birth cohort of 560 children with at least 1 parent with allergy or asthma was established in Baltimore, Boston, New York, and St Louis. Wheezing is assessed every 3 months, allergen-specific IgE yearly, and mononuclear cell cytokine responses at birth and yearly; environmental assessments include dust allergen and endotoxin, maternal stress, and indoor nicotine and nitrogen dioxide levels.

Results: Key outcomes in the first year include wheeze in 49%, 2 or more episodes of wheeze in 23%, eczema in 30%, and detectable IgE to milk, egg, and/or peanut in 32% and to cockroach in 4%. Household dust revealed levels of greater than 2 μg/g to cockroach in 40%, mite in 19%, cat in 25%, and mouse in 29%, and 66% of homes housed at least 1 smoker. Positive associations were detected between multiple wheeze and cotinine levels, maternal stress, and maternal depression, whereas cytokine responses to a variety of innate, adaptive, and mitogenic stimuli were inversely related to eczema.

Conclusions: This high-risk cohort of inner-city infants is exhibiting high rates of wheeze, eczema, and allergic sensitization. Low cytokine responses at birth might be a risk factor for eczema, whereas a variety of adverse environmental exposures contribute to the risk of wheezing in infancy. These findings provide evidence of specificity in the interactions between immune development, environmental exposures, and the development of early features that might predict future asthma.

Figure 1

Relationships between the major atopic outcomes. Includes those who have IgE data and EASI scores recorded at 3 or 12 months (n=332). Those who have no atopic outcomes (n=87, 26%) are included in the calculation of the percentages, but are not displayed in the Venn diagram. Significant associations were detected between eczema and sensitization (p=0.005).No associations were found between eczema and any, single, or multiple wheeze or between positive IgE and any, single or multiple episodes of wheeze.

Figure 2

Relationships between atopic outcomes and environmental exposures. Bold lines and filled circles represent statistical significance in models adjusted for site, season of birth, and gender of child. PSS=Perceived Stress Score, EPDS=Edinburgh Postnatal Depression Scale (mean of first-year measurements; OR for 5-level increase). ORs for cotinine and allergens are given for a 1-log increase.

Figure 3

Relationships between atopic outcomes and cord blood cytokine profiles. Bold lines and filled circles represent statistical significance in models adjusted for site, season of birth, and gender of child. Cytokine factors are scaled to 5 levels where 0=non-dectectable, and 1-4 represent quartiles of the detectable levels. ORs are given for a 1-step increase.