Asian dust exacerbates cedar pollen-induced allergic conjunctivitis in mice

Asian sand dust (ASD), a type of fine particulate matter originating from arid regions of East Asia, is known to exacerbate respiratory diseases, but its impact on the ocular surface remains poorly understood. Given the increasing prevalence of allergic conjunctivitis in Japan, particularly during the Japanese cedar pollen (JCP) season, we investigated whether ASD exposure aggravates ocular allergic inflammation. Using a mouse model sensitized with JCP, we found that conjunctival instillation of ASD in combination with JCP significantly increased clinical signs such as hyperemia and edema, along with elevated serum IgE levels and enhanced inflammatory cell infiltration compared to JCP alone. Histological analysis revealed epithelial disruption and increased infiltration of CD3-positive T cells and F4/80-positive macrophages in the ASD/JCP group. These findings demonstrate that ASD exacerbates allergic conjunctivitis by amplifying inflammatory responses on the ocular surface. Our study highlights ASD as a potential environmental risk factor for allergic eye diseases and offers novel mechanistic insights into how airborne pollutants interact with allergen-induced ocular inflammation.