Astragaloside IV Ameliorates Allergic Rhinitis Comorbid With Asthma by Inhibiting the Antigen‐Presenting Function of B Cells

Astragaloside IV (AST) is one of the main active components of Astragalus membranaceus (Fisch.) Bunge, possessing definite immunomodulatory properties. However, its efficacy and mechanism remain unclear in allergic rhinitis comorbid with asthma (ARCA). This study aims to investigate whether AST can improve ARCA by inhibiting antigen presentation. An ARCA mouse model was established to assess airway allergic symptoms; serum inflammatory factors were detected by ELISA, airway tissue pathology by HE, PAS and Masson staining and inflammatory factor expression, antigen-presenting cell activation and JAK2/STAT1 pathway activity by WB, IHC and IF. AST improved airway allergic symptoms, downregulated the expression of OVA-sIgE and IL-4 and upregulated the expression of OVA-sIgG. It also alleviated eosinophil infiltration, goblet cell metaplasia and collagen fibre proliferation and inhibited the expression of ECP, CD3e, CD4 and IL-4 in airway tissues. The antigen-presenting function of B cells in the airway tissues of ARCA mice was activated, while AST inhibited this function. Moreover, AST downregulated the expression of p-JAK2, STAT1, p-STAT1 and MHC II in airway tissues. In conclusion, B cells are the key effector cells mediating antigen presentation in the challenge phase of ARCA. AST can inhibit the antigen-presenting function of B cells via regulating the JAK2/STAT1 signalling pathway, thereby alleviating the Th2-type inflammatory response in ARCA.