Gleditsia sinensis Lam. aqueous extract attenuates nasal inflammation in allergic rhinitis by inhibiting MUC5AC production through suppression of the STAT3/STAT6 pathway

Allergic rhinitis (AR), a chronic respiratory inflammatory disease, is among the most common chronic diseases reported worldwide. Mucus hypersecretion is a critical feature of AR pathogenesis. Although the Gleditsia sinensis extract has several beneficial effects on human health, its effects on allergic inflammation have not yet been investigated. In this study, we examined the effects of G. sinensis aqueous extract (GSAE) on nasal inflammation in an ovalbumin (OVA)-induced AR mouse model. GSAE was administered orally for 1 week and then the clinical nasal symptoms were evaluated. The levels of histamine, OVA-specific immunoglobulin (Ig) E, and interleukin (IL)-13 were measured in the serum using an enzyme-linked immunosorbent assay (ELISA). Inflammatory cells were then counted in the nasal lavage fluid (NALF) and histopathology in the nasal epithelium was evaluated. STAT3/STAT6 phosphorylation was examined in primary human nasal epithelial cells (HNEpCs) using western blot analysis. Oral administration of GSAE to OVA-induced AR mice alleviated nasal clinical symptoms and reduced OVA-specific immunoglobulin E, interleukin (IL)-13, and histamine levels. The accumulation of eosinophils in nasal lavage fluid, nasal mucosa, mast cells, goblet cells, and mucin 5AC (MUC5AC) in the nasal epithelium was also inhibited by GSAE. Treatment with GSAE inhibited the production of MUC5AC in IL-4/IL-13-stimulated primary human nasal epithelial cells through the signal transducer and activator of transcription (STAT)3/STAT6 signaling pathway. These results indicated that GSAE reduces nasal inflammation suggesting that it is a potential treatment option for AR.