Urban Dust Microbiome: Impact on Later Atopy and Wheezing

Background: Investigations in urban areas have just begun to explore how the indoor dust microbiome may affect the pathogenesis of asthma and allery. Objective: We aimed to investigate the early fungal and bacterial microbiome in house dust with allergic sensitization and wheezing later in childhood. Methods: Individual dust samples from 189 homes of the LISAplus birth cohort study were collected shortly after birth from living room floors and profiled for fungal and bacterial microbiome. Fungal and bacterial diversity was assessed with terminal restriction fragment length polymorphism (tRFLP) and defined by Simpson's Diversity Index. Information on wheezing outcomes and covariates until the age of 10years was obtained by parent questionnaires. Information on specific allergic sensitization was available at child's age 6 and 10years. Logistic regression and general estimation equation (GEE) models were used to examine the relationship between microbial diversity and health outcomes. Results: Adjusted logistic regression analyses revealed a significantly reduced risk of developing sensitization to aero-allergens at 6years and ever wheezing until the age of 10years for exposure to higher fungal diversity [adjusted odds ratio (aOR) = 0.26 (95% CI: 0.10, 0.70), and 0.42 (95% CI: 0.18, 0.96), respectively]. The associations were attenuated for the longitudinal analyses (GEE) until the age of 10years. There was no association between higher exposure to bacterial diversity and the tested health outcomes. Conclusion: Higher early exposure to fungal diversity might help to prevent a child from developing sensitization to aero-allergens in early childhood, but the reasons for attenuated effects in later childhood require further prospective studies.