Analysis of allergen components and identification of bioactivity of HSP70 in pollen of Populus deltoides.

Background: Allergies caused by pollen from Populus deltoides are common, but the allergic components are still unclear.

Methods: The total proteins in pollen of P. deltoides were analyzed by proteomics, and the potential allergens were identified via the WHO/IUIS database and the allergenOnline database retrieval. One target protein was screened by bioinformatics and expressed in Escherichia coli. The biological activity of the expressed product was verified by animal experiments.

Results: The total of 3929 proteins in pollen of P. deltoides were identified, and 46 potential allergens belonging to 10 protein families were recognized by database retrieval. B9N9W6 protein of Hsp70 family was screened by bioinformatics analysis and expressed successfully. ELISA showed that B9N9W6 can stimulate the immune system to produce specific IgE and promote the generation of IL-4. Flow cytometry showed that B9N9W6 can significantly stimulate the proliferation of CD4⁺ T cells and promote the polarization of Th2 cells. The pathological sections of mice lung tissues indicated that alveolar destruction was more severe in the B9N9W6 group than that of extract group, and there were more inflammatory cells infiltration, mucus exudation and bleeding.

Conclusion: B9N9W6 is an important antigenic substance in the pollen of P. deltoides. Due to the conserved structure of Hsp70 family, more attention should be paid to the possibility of sensitization when Hsp70 from any pathogenic species is administered.