Bishop, C. R.; Rawle, D. J.; Yan, K.; Tang, B.; Larcher, T.; Suhrbier, A.

Global microplastic (MP) pollution is now well recognized, with humans and animals consuming and inhaling MPs on a daily basis. Herein we described the effects of azide-free, 1 um polystyrene MP beads co-delivered into lungs with a SARS-CoV-2 omicron BA.5 inoculum using a mouse model of mild COVID-19. Lung virus titres and viral RNA levels were not significantly affected by MPs, with overt clinical or histopathological changes also not observed. However, RNA-Seq of infected lungs revealed that MP exposure suppressed innate immune responses at 2 days post infection (dpi) and increased pro-inflammatory signatures at 6 dpi. The cytokine profile at 6 dpi showed a significant correlation with the cytokine release syndrome signature seen in some severe COVID-19 patients. This study adds to a growing body of literature suggesting that MPs can dysregulate inflammation in specific disease settings.