The association of early-life household endotoxin exposure with asthma, recurrent wheeze, and allergic sensitization in Canadian children 3 years of age

Asthma and allergies are the leading chronic illnesses among children in Canada, causing a significant burden on healthcare systems and negatively impacting the quality of life of children and their families. Currently, the association between asthma, wheeze, and atopy development and early-life exposure to endotoxin is not fully understood. Data from the CHILD Cohort Study were analyzed using multivariate logistic regression modelling to determine whether an association exists between household early-life endotoxin exposure measured in house dust and asthma, wheeze, and allergy development at 3 years of age. The models were adjusted for covariates relating to the child’s home environment, demographics and socioeconomic status. Those with higher household endotoxin concentrations showed lower odds of allergic sensitization at 3 years of age (OR 0.49, p=0.07 and OR 0.54, p=0.11) than those with the lowest household exposure. Sex stratification found that this relationship was specific to boys. No relationship was found between endotoxin exposure and recurrent wheeze at 3 years of age. Girls in homes with the highest exposure had lower odds of developing asthma by age 3 (p=0.10). These findings suggest endotoxin exposure in early life may protect against allergy at age 3 in Canadian children, particularly boys. Endotoxin is a measure of gram-negative bacteria but may be associated with the presence of ‘good’ microbes in the home environment as well. These findings are consistent with the hygiene hypothesis and encourage more research on early-life microbiome abundance and diversity.