Can Early-Life Indoor Microbial Diversity Increase the Risk of Allergic Rhinitis and Inhalant Atopy?

13 Jul, 21

Introduction

Allergic rhinitis (AR) and inhalant atopy during childhood increase the risk of asthma in later life. Epidemiological studies have shown that growing up in farming environment is inversely associated with risk of asthma and allergy. The link between indoor microbial exposure and asthma and atopy has been investigated. However, the data on microbial exposures in early childhood and development of AR and inhalant atopy later in childhood is lacking.

Aim

This study assesses whether early-life indoor microbial diversity in house dust can lead to development of AR and inhalant atopy later in childhood.

Methods

Study Design

Analyses of 2 birth cohort studies – LUKAS and LISA.

Patient Profile

Children within 2 birth cohorts
- LUKAS, a Finnish rural-suburban birth cohort (n=312)
- LISA, a German urban birth cohort from Munich and Leipzig study centers (n=248)

Treatment Strategy

Floor dust samples were collected at the age of 2 and 3 months in the LUKAS and LISA cohorts respectively.
Questionnaires on socioeconomic factors and environmental exposures were collected from parents at the child’s birth and at regular intervals up to the age of 10.5 and 15 years in the LUKAS and LISA cohorts respectively.
The indoor bacterial and fungal richness was analyzed.
Logistic regression analysis was done to determine AR and inhalant atopy at the age of 10 years.

Endpoints

Microbial diversity

Results

AR and atopy was prevalent in 11.5% and 46% in LUKAS and 10% and 42% in LISA respectively
Bacterial richness and Shannon entropy were significantly lower in the homes of children with AR as compared to those without AR in LISA. This trend was similar in LUKAS.
Significant correlations between bacterial and fungal diversity and the risk of inhalant atopy were observed. However, the correlations were inconsistent between the two cohorts.
Bacterial diversity was associated with an increased risk of inhalant atopy in rural areas, but with a lower risk in more urban areas.
Fungal richness and Shannon entropy was positively associated with inhalant atopy only in LISA.

Conclusion

The findings of this study revealed that a higher indoor bacterial diversity in early life might lower the risk of allergic rhinitis later in childhood.
This analysis demonstrates environment-dependent heterogeneity in the associations with inhalant atopy and suggests that specific constituents of the diversity might be relevant.

Environ Res. 2021 May; 196:110835.