The indoor microbiome and childhood asthma outcomes in the Columbia Center for Children's Environmental Health cohort

Sensitization to A. alternata and Alt a 1 is associated with adverse asthma outcomes. However, the influence of built environmental conditions and occupant behaviors on A. alternata and Alt a 1 exposure indoors remains understudied. We hypothesized that concentrations of A. alternata and Alt a 1 genes in house dust will correlate together and with concentrations of taxa in the family Pleosporaceae and order Pleosporales. Further, we hypothesized that concentrations of A. alternata and Alt a 1 genes in house dust will associate most strongly with indoor environmental conditions and occupant behaviors related to increased moisture conditions. We extracted DNA from floor dust samples collected in homes participating in the Columbia Children's Center for Environmental Health birth cohort. We quantified concentrations of fungal taxa through combined next-generation sequencing and quantitative polymerase chain reaction (qPCR). Alt a 1 concentration was quantified through specific qPCR assay. Levels of A. alternata were marginally increased in homes engaging in moisture-rich cleaning practices such as damp mopping (p=0.078) and homes with combined structural and behavioral factors related to higher moisture content, including use of a humidifier (p=0.065). Similar trends were observed for other taxa in the genus Alternaria, the family Pleosporaceae, and the order Pleosporales. Shannon fungal diversity was associated with the presence of bedroom carpet (p<0.001) and cleaning with a vacuum (p=0.032). Alt a 1 concentration did not associate strongly with environmental conditions and appeared to be driven by concentration of A. alternata in comparison to other related fungal taxa (rho=0.16; p=0.0037). Indoor A. alternata concentrations increased indoors with increased moisture content. Cleaning practices had different effects on fungal concentration and fungal diversity, implicating strategic differences for managing fungal exposures indoors. [This sequencing data was also used to examine the effects of indoor fungal exposures on childhood asthma outcomes in separate investigations].