Fungi in Early-Life House Dust Samples and the Development of Asthma: A Birth Cohort Study

RATIONALE: Fungal exposure has been associated with predisposing and protective effects on the development of childhood asthma. OBJECTIVE: To study whether early-life house dust mycobiota composition is associated with the development of asthma. METHODS: Mycobiota was determined by amplicon sequencing from 382 dust samples collected from living room floors, two months after birth in homes of the LUKAS cohort. Asthma status by 10.5 years of age was defined from questionnaires and assigned as ever (n=68) or current asthma (n=27). Inhalant atopy was clinically determined at the same age. Beta-composition was analysed using PERMANOVA-S, and asthma and atopy analyses were performed using discrete time hazard models and logistic regression, respectively. RESULTS: The house dust mycobiota composition based on Bray-Curtis (BC) distance was different in the homes of children who later did or did not develop asthma. The first and the fourth axes scores of Principal Coordinates Analysis (PCoA) based on BC were associated with ever asthma. Of the genera with the strongest correlation with these axes, the relative abundance of Boeremia, Cladosporium, Microdochium, Mycosphaerella and Pyrenochaetopsis showed protective associations with asthma. None of these associations remained significant after mutual adjustment among the five genera, or when mutually adjusted for other microbial cell wall markers and previously identified asthma protective bacterial indices. Neither fungal alpha-diversity nor load were associated with asthma in the whole population, but higher fungal richness was a risk factor among children in farms. Higher fungal loads (measured via qPCR) in house dust were associated with the risk of inhalant atopy. CONCLUSIONS: The results of our analyses from this well-characterized birth cohort suggest that the early life house dust mycobiota in Finnish homes, characterized via DNA amplicon sequencing, do not have strong predisposing or protective effects on asthma development.

• Täubel, M.
• Jalanka, J.
• Kirjavainen, P. V.
• Tuoresmäki, P.
• Hyvärinen, A.
• Skevaki, C.
• Piippo-Savolainen, E.
• Pekkanen, J.
• Karvonen, A. M.