Art an 3 as a candidate recombinant antigen for Artemisia pollen immunotherapy: comparative efficacy and mechanistic insights.

BACKGROUND: Artemisia pollen is a major cause of seasonal respiratory allergy, yet allergen-specific immunotherapy (AIT) still relies mainly on crude extracts. Art an 3 is a major Artemisia annua pollen allergen, but its therapeutic and immunological features relative to extracts remain unclear. OBJECTIVE: To compare recombinant Art an 3 (rArt an 3)-based versus extract-based subcutaneous immunotherapy (SCIT) in an A. annua pollen-induced murine asthma model. METHODS: Female BALB/c mice were sensitized and intranasally challenged with A. annua pollen extract, then treated with Extracts-SCIT, rArt an 3-SCIT, or PBS. Airway hyperresponsiveness (AHR), lung histopathology, bronchoalveolar lavage fluid (BALF) cells, splenic cytokines, serum immunoglobulins, and splenic CD4+ T-cell subsets were evaluated. RESULTS: Both SCIT regimens reduced peribronchial inflammation, goblet-cell mucus, and methacholine-induced AHR versus positive controls; histologic improvement tended to be greater with Extracts-SCIT, whereas AHR improvement was comparable. Extracts-SCIT more clearly decreased BALF eosinophils and IL-5/IL-17A. rArt an 3-SCIT preferentially increased IL-10 and IFN-γ and enhanced splenic Treg/Th1 responses. Pollen-specific sIgE decreased most with Extracts-SCIT, while rArt an 3-SCIT showed a modest sIgE reduction but a more pronounced increase in pollen-specific sIgG1. CONCLUSION: rArt an 3-SCIT showed overall protection comparable to Extracts-SCIT, with a regulatory/Th1-associated profile characterized by increased Treg/Th1 responses and pollen-specific sIgG1, supporting rArt an 3 as a molecularly defined AIT candidate for Artemisia pollen allergy.