Pollen-derived extracellular vesicles promotes allergic airway inflammation

Asthma remains a global health burden, affecting over 300 million individuals worldwide, with its pathogenesis involving complex interactions between genetic predisposition and environmental allergens. Pollen is a well-established trigger of allergic asthma. However, the precise mechanisms underlying its allergenic activity remain incompletely understood. Recent advances have highlighted the emerging role of plant-derived extracellular vesicles in immune modulation. Notably, pollen-derived extracellular vesicles (PDEVs) have been identified as carriers of allergenic proteins. Therefore, this study investigates whether pollen contains extracellular vesicles(EVs) and whether these vesicles can induce allergic airway inflammation.

We isolated extracellular vesicles from Artemisia annua pollen using differential centrifugation and sucrose density gradient ultracentrifugation. The biological activity of PDEVs was evaluated in vitro using human airway epithelial cells (BEAS-2B) and in vivo using a murine asthma model.

PDEVs are nanoscale lipid bilayer structures containing diverse allergenic proteins and exhibiting structural stability. PDEVs induced significantly stronger pro-inflammatory responses compared to pollen supernatant (Sup) in vitro. PDEVs enhanced inflammatory cytokine production IL-4, IL-5, IL-13, IL-33 expression, and promoted eosinophilic, neutrophilic infiltration in murine.

Our findings suggest extracellular vesicles present in pollen grains, which may represent a critical mechanism underlying pollen-induced airway inflammation. Targeting PDEVs may offer new therapeutic strategies for allergic airway diseases prevention and treatment.