Indoor microbial communities: Influence on asthma severity in atopic and nonatopic children

Abstract

Background Allergic and non-allergic asthma severity in children can be affected by microbial exposures. Objective Examine associations between exposures to household microbes and childhood asthma severity stratified by atopic status. Methods Participants (n=196) were selected from a cohort of asthmatic children in Connecticut and Massachusetts, USA. Children were grouped according to asthma severity (mild with no or minimal symptoms and medication, or moderate to severe persistent) and atopic status (determined by serum IgE). Microbial community structure and concentrations in house dust were determined using next-generation DNA sequencing and quantitative Polymerase Chain Reaction. Logistic regression was used to explore associations between asthma severity and exposure metrics, including richness, taxa identification and quantification, community composition, and concentration of total fungi and bacteria. Results Among all children, increased asthma severity was significantly associated with elevated concentration of summed allergenic fungal species, high total fungal concentration, and high bacterial richness by logistic regression, in addition to microbial community composition by distance comparison t-test. Asthma severity in atopic children was associated with fungal community composition (p=0.001). By logistic regression, asthma severity in non-atopic children was associated with total fungal concentration: odds ratio 2.40, 95% confidence interval 1.06–5.44. The fungal genus Volutella was associated with increased asthma severity in atopic children (p=0.0001, q=0.04). Yeast genera Kondoa may be protective; Cryptococcus may also impact asthma severity. Conclusion Asthma severity among this cohort of children was associated with microbial exposure, and associations differed based on atopic status.

Fungal Exposure and Asthma: IgE and Non-IgE-Mediated Mechanisms

“…Dannemiller et al [58•] used quantitative PCR (qPCR) and next-generation sequencing (NGS) to analyze archived dust samples collected from the homes of asthmatic children. Asthma severity was associated with the total concentration of fungi analyzed by the qPCR.…”

Bedroom Allergen Exposure Beyond House Dust Mites

“…In numerous studies, residential fungal exposures have been associated with asthma exacerbations and severity [142, 158, 163, 164•, 166, 167]. Although most of the asthma-related studies have been case-control studies or cross-sectional in nature, supporting data has also emerged from birth cohort studies [142, 158, 164•, 168–170].…”

“…Although most of the asthma-related studies have been case-control studies or cross-sectional in nature, supporting data has also emerged from birth cohort studies [142, 158, 164•, 168–170]. In a recent study, asthma severity in atopic children was associated with fungal community composition, whereas in non-atopic children asthma severity was related to levels of total fungi, suggesting that effects of fungal exposures may differ by asthma subtypes [167]. However, protective effects of early-life fungal exposures have also been reported.…”

The mutual influences of man-made pollutants and allergic manifestations

“…Furthermore, indoor exposure also includes combustion of solid fuels indoors, tobacco smoking and poor ventilation (Jiang, Mei et al, 2016). This poor ventilation can lead to a build-up of another indoor pollutant, house dust, which has been shown to affect people with lung diseases through its' microbial content (Dannemiller, Gent et al, 2016).…”