Exposure to higher indoor levels of pet or pest allergens during infancy may be associated with a lower risk of asthma in children at high risk, according to the 7-year results from the ongoing Urban Environment and Childhood Asthma (URECA) study, published in the Journal of Allergy and Clinical Immunology.
Over 8% of children in the United States currently have asthma, according to the Centers of Disease Control and Prevention.
“We are learning more and more about how the early-life environment can influence the development of certain health conditions,” said Anthony S. Fauci, MD, director of the National Institutes of Health’s National Institute of Allergy and Infectious Diseases (NIAID). “If we can develop strategies to prevent asthma before it develops, we will help alleviate the burden this disease places on millions of people, as well as on their families and communities.”
Since 2005, researchers of the URECA study have enrolled 560 newborns in Baltimore, Boston, New York City, and St. Louis who were at high risk for developing asthma due to at least one parent having asthma or allergies. These children have been followed since birth. With this study, researchers sought to identify early-life environmental risk factors for childhood asthma.
For this current analysis, they included 7-year data from 442 children, in whom they assessed the relationship of prenatal and early-life environmental factors on the incidence of asthma at 7 years of age.
Researchers found that higher house dust concentrations of cockroach, mouse, and cat allergens during the first 3 years of life were associated with a lower risk of asthma.
Using 16S ribosomal RNA sequencing, they also analyzed house dust microbiomes, and identified 202 and 171 bacterial taxa that were significantly more or less abundant in the homes of children with asthma. Most of these bacteria were significantly correlated with one or more allergen concentrations.
These results support those from a previous assessment of URECA, in which researchers concluded that exposure to certain bacteria during infancy may protect 3-year-olds from recurrent wheezing, which is a risk factor for asthma.
Also bolstering findings from this previous URECA analysis, results from the current analysis showed a significantly positive association between maternal stress and depression scores and asthma, as were umbilical cord plasma cotinine concentration, which are a marker for smoking (OR per geometric SD increase in concentration: 1.76; 95% CI: 1.00-3.09; P=0.048).
“Our observations imply that exposure to a broad variety of indoor allergens, bacteria and bacterial products early in life may reduce the risk of developing asthma,” said senior author and principal investigator James E. Gern, MD, professor, University of Wisconsin-Madison, Madison, WI. “Additional research may help us identify specific targets for asthma prevention strategies.”
Dr. Gern and colleagues will continue to monitor these children, and further study which early-life factors may affect the development of allergic and non-allergic asthma.
This work was funded by NIAID under award numbers AI025496, AI25482, HHSN272200900052C, HHSN272201000052I, AI114271-01 and AI117870. NIH’s National Center for Advancing Translational Science provided additional support under award numbers RR00052, RR00533, RR025771, RR00071, RR024156, and RR024992-02, TR001079 and UL1TR000040.
The URECA study is no longer recruiting, but more information is available at ClinicalTrials.gov using identifier NCT00114881.