These results add to the growing evidence that the optimal conditions to promote tolerance may be early life exposure to those allergens and bacteria identified in the study.”
– James Gern
The study, funded by the National Institutes of Health (NIH), was published today in the Journal of Allergy and Clinical Immunology.
Their observations are part of the Urban Environment and Childhood Asthma (URECA) study, which aims to identify factors responsible for asthma development in children from inner-city settings, where the disease is more prevalent and severe.
Since 2005, the URECA study has enrolled 560 children from four cities – Baltimore, Boston, New York and St. Louis. These children have at least one parent with asthma or allergies, placing them at high risk for developing asthma. The study is following the children from birth, and the current publication evaluates the group through three years of age.
“Our observations suggest that children in inner-city environments with the highest exposure to specific allergens and bacteria during their first year of life were less likely to develop recurrent wheeze and allergic disease,” says Dr. James Gern, principal investigator for the University of Wisconsin Asthma and Allergic Diseases Clinical Research Center. “These results add to the growing evidence that the optimal conditions to promote tolerance may be early life exposure to those allergens and bacteria identified in the study.”
During early life, recurrent wheezing and sensitivity to common allergens are risk factors for developing asthma. In the current study, the researchers measured the frequency of wheezing episodes and levels of exposure to five common inner-city allergens – cat, cockroach, dog, dust mite and mouse.
Surprisingly, they found that exposure to cockroach, mouse and cat during the first three years of life was associated with a lower risk of recurrent wheezing by age three.
A smaller study within the URECA group tested whether bacteria, measured in house dust, influence the risk of wheezing and allergy. Researchers separated 104 children into four groups: no wheezing or sensitivity to allergens, wheezing only, sensitivity to allergens only, or both wheezing and sensitivity to allergens.
They found that children with no wheezing or sensitivity to allergens were more likely to have encountered high levels of allergens and a greater variety of bacteria, particularly those belonging to the Bacteriodes and Firmicutes groups, during their first year of life. The study, which was conducted by investigators at numerous institutions, is the first to consider exposures to both allergens and bacteria in the same population.
The URECA study was funded by NIH’s National Institute of Allergy and Infectious Disease, through its Inner-City Asthma Consortium (grant numbers NO1-AI-25496, NO1-AI-25482, HHSN272200900052C, and HHSN272201000052I. Additional support was provided by NIH’s National Center for Advancing Translational Sciences, under grants RR00052, M01RR00533, 1UL1RR025771, M01RR00071, 1UL1RR024156, and 5UL1RR024992-02.