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 α-diversity and taxonomic composition. Methods We investigated structure and characteristics of the microbiota of 40 healthy subjects through metabarcoding analysis of the V3–V4 regions of the 16s rRNA gene. Exposure to PM10and PM2.5was 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 PM10and PM2.5levels of the 3rd day preceding sampling (Day -3) and α-diversity indices (Chao1, 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.