Urban Dust Microbiome: Impact on Later Atopy and Wheezing

Abstract

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 10 years was obtained by parent questionnaires. Information on specific allergic sensitization was available at child’s age 6 and 10 years. 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 6 years and ever wheezing until the age of 10 years 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 10 years. 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.Citation:Tischer C, Weikl F, Probst AJ, Standl M, Heinrich J, Pritsch K. 2016. Urban dust microbiome: impact on later atopy and wheezing. Environ Health Perspect 124:1919–1923; http://dx.doi.org/10.1289/EHP158

Environmental determinants of allergy and asthma in early life

“…However, while increased levels of β-1,3-glucan may certainly indicate greater fungal concentrations, it may also represent a more diverse fungal population. In fact, exposure to greater fungal diversity offered protection against sensitization to aeroallergens and early childhood wheeze in a German longitudinal birth cohort, mirroring the protective effects of microbial diversity in the human microbiome 102 . Importantly, the predictive effect of fungal exposure on asthma development seems to occur independently of fungal sensitization.…”

Indoor bacterial microbiota and development of asthma by 10.5 years of age

“…We have previously shown in this cohort that the quantity of exposure to bacterial and fungal cell-wall components in early life has a bell-shaped association with asthma at the age of 6 years. 9 Studies with DNA-based methods have indicated that the asthmaprotective characteristics might include diversity [10][11][12][13] or, more specifically, diversity within certain taxa and a lack of predisposing microbes. [14][15][16][17] However, it remains unclear whether there are specific individual taxa in the indoor microbiome that are independently associated with reduced asthma risk.…”

Indoor allergen exposure and asthma outcomes

“…For example, Tischer et al [32 ▪▪ ] found that exposure to higher fungal diversity shortly after birth was associated with a decreased risk of developing wheezing and aeroallergen sensitization in later childhood. Future work should continue to evaluate the role of fungal diversity on the development of atopic conditions.…”