Background Wheezing illnesses cause major morbidity in infants and are frequent precursors to asthma. Objective To examine environmental factors associated with recurrent wheezing in inner-city environments. Methods The Urban Environment and Childhood Asthma (URECA) study examined a birth cohort at high risk for asthma (n=560) in Baltimore, Boston, New York, and St. Louis. Environmental assessments included allergen exposure, and in a nested case-control study of 104 children, the bacterial content of house dust collected in the first year of life. Associations were determined among environmental factors, aeroallergen sensitization, and recurrent wheezing at age three. Results Cumulative allergen exposure over the first three years was associated with allergic sensitization, and sensitization at age three was related to recurrent wheeze. In contrast, first year exposure to cockroach, mouse and cat allergens was negatively associated with recurrent wheeze (OR 0.60, 0.65, and 0.75, p≤0.01). Differences in house-dust bacterial content in the first year, especially reduced exposure to specific Firmicutes and Bacteriodetes, was associated with atopy and atopic wheeze. Exposure to high levels of both allergens and this subset of bacteria in the first year of life was most common among children without atopy or wheeze. Conclusions In inner-city environments, children with the highest exposure to specific allergens and bacteria during their first year were least likely to develop recurrent wheeze and allergic sensitization. These findings suggest that concomitant exposure to high levels of certain allergens and bacteria in early life may be beneficial, and suggest new preventive strategies for wheezing and allergic diseases.

Among high-risk inner-city children, higher indoor levels of pet or pest allergens in infancy were associated with lower risk of asthma. The abundance of a number of bacterial taxa in house dust was associated with increased or decreased asthma risk. Prenatal tobacco smoke exposure and higher maternal stress and depression scores in early life were associated with increased asthma risk.

Rationale Previous data suggest that food allergy may be more common in inner-city children; however, these studies have not collected data on both sensitization and clinical reactivity, or early life exposures. Methods Children in the URECA birth cohort were followed through age 5 years. Household exposures, diet, clinical history, and physical examinations were assessed yearly; specific-IgE to milk, egg, and peanut were measured at 1, 2, 3, and 5 years. Based on sensitization (IgE≥0.35 kU/L) and clinical history over the five-year period, children were classified as food allergic (FA), possibly allergic, sensitized but tolerant, or not allergic/not sensitized. Results 516 children were included. Overall, 55.4% were sensitized (milk 46.7%, egg 31.0%, peanut 20.9%), while 9.9% were categorized as FA (peanut 6.0%, egg 4.3%, milk 2.7%, 2.5% >1 food). The remaining children were categorized as possibly allergic (17.0%), sensitized but tolerant (28.5%), and not sensitized (44.6%). Eighteen (3.5%) reported reactions to foods for which IgE was not measured. Food-specific IgE levels were similar in FA versus sensitized but tolerant children, except for egg, which was higher in FA at ages 1 and 2. FA was associated with recurrent wheeze, eczema, aeroallergen sensitization, male gender, breastfeeding, and lower endotoxin exposure in year 1, but not with race/ethnicity, income, tobacco exposure, maternal stress, or early introduction of solid foods. Conclusions Even given that this was designed to be a high-risk cohort, the cumulative incidence of food allergy is extremely high, especially considering the strict definition of food allergy that was applied and that only 3 common allergens were included.

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Rationale: Maternal depression and prenatal and early life stress may influence childhood wheezing illnesses, potentially through effects on immune development.Objectives: To test the hypothesis that maternal stress and/or depression during pregnancy and early life are associated with recurrent wheezing and aeroallergen sensitivity and altered cytokine responses (enhanced type 2 or reduced virus-induced cytokine responses) from stimulated peripheral blood mononuclear cells at age 3 years.Methods: URECA (Urban Environment and Childhood Asthma) is a birth cohort at high risk for asthma (n = 560) in four inner cities. Maternal stress, depression, and childhood wheezing episodes were assessed by quarterly questionnaires beginning at birth. Logistic and linear regression techniques were used to examine the relation of maternal stress/depression to recurrent wheezing and peripheral blood mononuclear cell cytokine responses at age 3 years.Measurements and Main Results: Overall, 166 (36%) children had recurrent wheeze at age 3 years. Measures of maternal perceived stress at Years 2 and 3 were positively associated with recurrent wheeze (P , 0.05). Maternal depression (any year) was significantly associated with recurrent wheezing (P < 0.01). These associations were also significant when considered in a longitudinal analysis of cumulative stress and depression (P < 0.02). Neither stress nor depression was significantly related to aeroallergen sensitization or antiviral responses. Contrary to our original hypothesis, prenatal and Year 1 stress and depression had significant inverse associations with several type 2 cytokine responses. Conclusions:In urban children at high risk for asthma, maternal perceived stress and depression were significantly associated with recurrent wheezing but not increased atopy or reduced antiviral responses.