Inflammatory Effects of Particulate Matter Exposure on the Nasal and Paranasal Sinus Mucosa in Rats

Particulate matter (PM) is a major environmental pollutant implicated in various respiratory diseases. However, its impact on the upper respiratory tract, particularly the nasal and paranasal sinus mucosa, remains poorly understood. This study aimed to investigate the acute inflammatory effects of PM exposure on the sinonasal mucosa and evaluate the natural recovery process in a controlled rat model. Ten-week-old male Sprague Dawley rats were exposed to incense-derived PM in a custom-designed exposure chamber for 2 h daily for seven consecutive days. Rats were sacrificed at 3, 7, and 14 days post-exposure. Histopathologic changes were assessed using hematoxylin and eosin and Alcian blue staining, and mucosal gene expression of inflammatory cytokines including interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and IL-5 and MUC5AC was quantified using real-time reverse transcription polymerase chain reaction. PM exposure induced significant histological alterations, including epithelial thickening, inflammatory cell infiltration, and goblet cell hyperplasia, which peaked at 7 days post-exposure. Expression levels of TNF-α and IFN-γ were significantly elevated at 7 days compared to controls. The sinonasal mucosa in the 14-day post-exposure groups exhibited a remarkable decrease in goblet cell numbers, and IL-1β and TNF-α expression. Short-term exposure to high concentrations of PM resulted in acute inflammatory changes in the sinonasal mucosa of rats, including epithelial thickening and goblet cell hyperplasia. These changes were partially resolved after exposure ended, indicating that PM-induced sinonasal inflammation may be at least partially reversible.