THE EFFECT OF INDOOR TOTAL SUSPENDED PARTICLES (TSP) ON THE HUMAN UPPER RESPIRATORY SYSTEM: FROM THE MICROBIOME TO HERV METHYLATION

Air pollution is well known for its adverse effects on human health. Among all air contaminants, particulate matter is one of the most studied because of its effect on the cardiovascular and respiratory system. Almost the entire global population is exposed daily to an unhealthy level of these contaminants and most of the exposure comes from the indoor setting where we spend a large portion of our daily time. The link between particulate matter exposure and human disease is still not fully understood, although inflammation is commonly observed after exposure to particulate matter. For that reason, investigating how the upper respiratory microbiome responds to particulate matter exposure is critical. These microorganisms that inhabit our upper airways play a crucial role in the homeostasis of the immune system and defend against external environmental stimuli. Furthermore, inflammation is also correlated with the activation of human endogenous retroviral elements integrated in our genome, the HERV genes. These genes regulate essential processes, and their dysregulation is associated with various inflammatory and immune-related diseases. The aim of this project is to investigate the effects of indoor Total Suspended Particles (TSP) on the upper respiratory microbiome and the methylation levels of HERV genes. Additionally, this study aims to examine whether the microbiome can influence the effect that indoor TSP has on HERV methylation. To achieve this aim, we recruited 34 healthy office workers from the University of Milan and the University of Como. We monitored them and their workplaces for six weeks total, three weeks during the winter and three weeks during the summer. At the end of every week, we collected both environmental and biological samples. The TSP samples were collected using an active filter-based technique. The biological samples included anterior nares and nasopharynx swabs to evaluate the upper respiratory microbiome, and buccal brushes to measure the HERV methylation. The first part of the ...