“Divergent TLR2 and TLR4 activation by fungal spores and species diversity in dust from waste-sorting plants”

1. This manuscript presents the results of an exploratory study on the relationships between NFkB (Nuclear Factor Kappa Chain Enhancer of B-cells) response through TLRs activation by dust characterized by fungal spore concentrations and species diversity. Personal total dust samples were collected from Norwegian waste sorting plants and then characterized for fungal spores and fungal species diversity, as well as for other bioaerosol components, including endotoxins and actinobacteria. The ability of the dust to induce an NFkB response by activating Toll-like receptors 2 (TLR2) and 4 (TLR4) in vitro was evaluated as well as the relationship between such responses and quantifiable bioaerosol components. The average concentrations of bioaerosols were 7.23 mg total dust m −3 , 4.49×10 5 fungal spores m −3 , 814 endotoxin units m −3 , and 0.6×10 5 actinobacteria m −3 . The mean diversity measurements were 326; 0.59 and 3.39 for fungal richness, evenness, and Shannon Index, respectively. Overall, fungal OTUs belonging to the Ascomycotina phylum were most abundant (55%), followed by Basidiomycota (33%) and Mucormycota (3%). All samples induced significant NFkB responses through TLR2 and TLR4 activation. While fungal spore levels were positively associated with TLR2 and TLR4 activation, there was a trend that fungal species richness was negatively associated with the activation of these receptors. This observation supports the existence of divergent immunological responses relationship between fungal spore levels and fungal species diversity. Such relationships seem to be described for the first time for dust from waste facilities.