title: Effects of early-life exposure to allergens and bacteria on recurrent wheeze and atopy in urban children.
abstract: BACKGROUND
  Wheezing illnesses cause major morbidity in infants and are frequent precursors to asthma.
  
  
  OBJECTIVE
  We sought to examine environmental factors associated with recurrent wheezing in inner-city environments.
  
  
  METHODS
  The 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.
  
  
  RESULTS
  Cumulative 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.
  
  
  CONCLUSIONS
  In 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.
authors.affiliation: Department of Medicine, University of California, San Francisco, Calif.
authors.forename: Susan V
authors.initials: SV
authors.lastname: Lynch
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md. Electronic address: rwood@jhmi.edu.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wood
authors.affiliation: Department of Medicine, University of California, San Francisco, Calif.
authors.forename: Homer
authors.initials: H
authors.lastname: Boushey
authors.affiliation: Department of Pediatrics, Washington University School of Medicine and St Louis Children's Hospital, St Louis, Mo.
authors.forename: Leonard B
authors.initials: LB
authors.lastname: Bacharier
authors.affiliation: Department of Pediatrics, Washington University School of Medicine and St Louis Children's Hospital, St Louis, Mo.
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Bloomberg
authors.affiliation: Division of Pediatric Allergy and Immunology, Columbia University Medical Center, New York, NY.
authors.forename: Meyer
authors.initials: M
authors.lastname: Kattan
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Mass.
authors.forename: George T
authors.initials: GT
authors.lastname: O'Connor
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Mass.
authors.forename: Megan T
authors.initials: MT
authors.lastname: Sandel
authors.affiliation: Rho, Inc, Chapel Hill, NC.
authors.forename: Agustin
authors.initials: A
authors.lastname: Calatroni
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Matsui
authors.affiliation: Division of Allergy and Immunology Henry Ford Health System, Detroit, Mich.
authors.forename: Christine C
authors.initials: CC
authors.lastname: Johnson
authors.affiliation: Rho, Inc, Chapel Hill, NC.
authors.forename: Henry
authors.initials: H
authors.lastname: Lynn
authors.affiliation: Rho, Inc, Chapel Hill, NC.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Visness
authors.affiliation: Rho, Inc, Chapel Hill, NC.
authors.forename: Katy F
authors.initials: KF
authors.lastname: Jaffee
authors.affiliation: National Institute of Allergy and Infectious Diseases, Bethesda Md.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Gergen
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass.
authors.forename: Diane R
authors.initials: DR
authors.lastname: Gold
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass.
authors.forename: Rosalind J
authors.initials: RJ
authors.lastname: Wright
authors.affiliation: Department of Medicine, University of California, San Francisco, Calif.
authors.forename: Kei
authors.initials: K
authors.lastname: Fujimura
authors.affiliation: Department of Medicine, University of California, San Francisco, Calif.
authors.forename: Marcus
authors.initials: M
authors.lastname: Rauch
authors.affiliation: Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wis.
authors.forename: William W
authors.initials: WW
authors.lastname: Busse
authors.affiliation: Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wis.
authors.forename: James E
authors.initials: JE
authors.lastname: Gern
mesh_terms: D000485:Allergens / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D001249:Asthma / Q000209:etiology / Q000276:immunology* / Q000517:prevention & control; D001419:Bacteria / Q000276:immunology* / Q000302:isolation & purification; D016022:Case-Control Studies; D002675:Child, Preschool; D015331:Cohort Studies; D004391:Dust / Q000032:analysis; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012008:Recurrence; D012135:Respiratory Sounds / Q000209:etiology / Q000276:immunology*; D012306:Risk; D014481:United States; D014505:Urban Population
chemical_list: D000485:Allergens; D000942:Antigens, Bacterial; D004391:Dust
keywords: Asthma; allergen exposure; atopy; inner city; microbial exposure