Early-life environmental exposures and development of childhood asthma

In Canada, a striking 13% of children (~500,000) have asthma. It is the leading cause of absenteeism from school, and accounts for more than 30% of Canadian health care billings for children. Asthma is also the leading cause of hospital admissions in both children and the general Canadian population. Given that asthma typically begins in childhood and lasts throughout life, the high prevalence, combined with significant related morbidity, make asthma the most common and burdensome chronic non-communicable disease affecting young Canadians. 

Asthma is a complex disease dependent on the interactions of genetic predisposition with environmental factors including physical, microbial, and social environments. The Canadian Healthy Longitudinal Development (CHlLD), a cohort study funded by CIHR, has recruited over 3,500 pregnant mothers to collect such environmental and biological data from pregnancy up to age five in four Canadian cities: Vancouver, Edmonton, Toronto and Winnipeg. The proposed project will use biological and environmental data from the CHILD cohort and will focus on traffic-related air pollution and natural spaces. These two modifiable environmental exposures have been shown to be associated with asthma exacerbation.

The novelty of this research lies in the study of joint exposures and their interactions over time; their impact likely depends not only on individual genetic profiles, but also on the critical timing of exposure. Early life period, including in utero, is a critical influence on health in later life. Likewise, changes in gene function in relation to environmental influences provide evidence to explain how and why asthma and allergies exist and progress. 

Dr. Sbihi’s research will examine how these changes, called epigenetic modifications, are affected by the early-life environmental exposures, including the body’s microbial milieu. By examining how the environmental exposures (traffic air pollutants, natural spaces, gut microbes) impact DNA methylation and consequently how these epigenetics modifications lead to asthma, we will be able to better understand the mechanisms of asthma development and subsequently provide better targeted prevention measures.