17 Effects of Indoor Air Pollution on Both a Healthy and “an Inflamed” Model of the Alveolar Barrier in Vitro.

Abstract Exposure to indoor air pollutants (IAP) has increased recently, with people spending more time indoors. Increased exposures of IAP on a healthy population are poorly understood, and those with allergic respiratory conditions less so. The objective of this study, therefore, was to implement a well-characterised in vitro model of the human alveolar epithelial barrier (A549+PMA differentiated THP-1 incubated with/without IL-13, IL-5 and IL-4) to determine the effects of a standardised indoor particulate (NIST2583) on both a healthy lung model and modelling a type-II inflammatory response. Using concentrations from the literature, and an environmentally appropriate exposure we investigated 232, 464 and 608ng/cm2 of NIST2583 respectively. Membrane integrity (blue dextran), viability (trypan blue), genotoxicity (micronucleus (Mn) assay) and (pro-) and (anti-)inflammatory effects (IL-6, IL-8, IL-33, and IL-10) were then assessed 24hours post exposure to both models. No changes in Mn frequency or membrane integrity in either model was noted when exposed to any concentration of NIST2583 tested. Though, a significant decrease (p<0.05) in viability at the highest concentration was observed in the healthy model. Whilst cell viability in the “inflamed” model significantly decreased (p<0.05) at the lower concentrations. A significant reduction (p<0.05) in IL-10 and increase in IL-33 was seen after exposure to NIST2583 in the “inflamed” model. Collectively, the results indicate the potential for IAP to cause the onset of an allergic response as well as exacerbating pre-existing allergic conditions. Furthermore, the data imposes the importance of considering unhealthy individuals when investigating the potential health effects of IAP.