• Susan V Lynch, Robert A Wood, Homer Boushey, Leonard B Bacharier, Gordon R Bloomberg, Meyer Kattan, George T O'Connor, Megan T Sandel, Agustin Calatroni, Elizabeth Matsui, Christine C Johnson, Henry Lynn, Cynthia M Visness, Katy F Jaffee, Peter J Gergen, Diane R Gold, Rosalind J Wright, Kei Fujimura, Marcus Rauch, William W Busse, and James E Gern.
• Department of Medicine, University of California, San Francisco, Calif.
• J. Allergy Clin. Immunol. 2014 Sep 1; 134 (3): 593-601.e12.

BackgroundWheezing illnesses cause major morbidity in infants and are frequent precursors to asthma.ObjectiveWe sought to examine environmental factors associated with recurrent wheezing in inner-city environments.MethodsThe Urban Environment and Childhood Asthma 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 3 years.ResultsCumulative allergen exposure over the first 3 years was associated with allergic sensitization, and sensitization at age 3 years was related to recurrent wheeze. In contrast, first-year exposure to cockroach, mouse, and cat allergens was negatively associated with recurrent wheeze (odds ratio, 0.60, 0.65, and 0.75, respectively; P ≤ .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.ConclusionsIn inner-city environments children with the highest exposure to specific allergens and bacteria during their first year were least likely to have recurrent wheeze and allergic sensitization. These findings suggest that concomitant exposure to high levels of certain allergens and bacteria in early life might be beneficial and suggest new preventive strategies for wheezing and allergic diseases.Copyright © 2014 American Academy of Allergy, Asthma & Immunology. All rights reserved.

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