Platycodin D inhibits interleukin-13-induced the expression of inflammatory cytokines and mucus in nasal epithelial cells.

Allergic rhinitis (AR) is a common chronic inflammatory condition of the nasal mucosal tissue. Platycodin D (PLD), a triterpenoid saponin isolated from the root of Platycodon grandiflorum, has anti-inflammatory effects in a mouse model of allergic asthma. However, the anti-inflammatory effects of PLD in the nasal mucosa have not been deeply investigated. The objective was to investigate the effect of PLD on inflammatory cytokines and mucus production from nasal epithelial cells. Our study showed that PLD inhibited the levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and eotaxin in interleukin (IL)-13-stimulated RPMI2650 cells. PLD also suppressed IL-13-induced mucin 5AC (MUC5AC) expression in RPMI2650 cells. Moreover, PLD treatment prevented IL-13-induced p-NF-κB p65 expression in RPMI2650 cells, as well as MAPK signaling pathway activation. Taken together, our results provided evidence that PLD inhibits IL-13-induced the expression of inflammatory cytokines and mucus in nasal epithelial cells by inhibiting the activation of NF-κB and MAPK signaling pathways.