Short-term particulate matter exposure influences nasal microbiota in a population of healthy subjects

Background: Exposure to air pollutants, such as particulate matter (PM), represents a growing health problem. The aim of our study was to investigate whether PM could induce a dysbiosis in the nasal microbiota in terms of alpha-diversity and taxonomic composition. Methods: We investigated structure and characteristics of the microbiota of 40 healthy subjects through meta-barcoding analysis of the V3-V4 regions of the 16s rRNA gene. Exposure to PM10 and PM2.5 was assessed with a personal sampler worn for 24 h before sample collection (Day -1) and with measurements from monitoring stations (from Day -2 to Day -7). Results: We found an inverse association between PM10 and PM2.5 levels of the 3rd day preceding sampling (Day -3) and alpha-diversity indices (Chaol, Shannon and PD_whole_tree). Day -3 PM was inversely associated also with the majority of analyzed taxa, except for Moraxella, which showed a positive association. In addition, subjects showed different structural profiles identifying two groups: one characterized by an even community and another widely dominated by the Moraxella genus. Conclusions: Our findings support the role of PM exposure in influencing microbiota and altering the normal homeostasis within the bacterial community. Whether these alterations could have a role in disease development and/or exacerbation needs further research.