Purified polysaccharides of Tetrastigma hemsleyanum diels et gilg alleviate allergic rhinitis by regulating Th17 cell differentiation and suppressing pro-inflammatory cytokines.

Allergic rhinitis (AR) is a chronic, non-infectious inflammatory disease of the nasal mucosa mediated by immunoglobulin E (IgE) and involves various immune cells and factors. Previous studies have demonstrated that THP5, an active component isolated from the crude polysaccharides of Tetrastigma hemsleyanum Diels et Gilg, exhibits immunomodulatory effects. This study investigated the therapeutic efficacy and underlying mechanisms of nebulized THP5 in the treatment of AR using an ovalbumin (OVA)-induced AR mouse model and compared its effects with oral administration. Comparative analysis indicates that nebulized and orally administered THP5 show comparable efficacy in the treatment of AR through evaluation of various parameters. Results showed that nebulized THP5 significantly alleviated nasal symptoms and pathological changes in AR mice, reduced serum levels of IgE, IL-17 A, and IL-1β, and suppressed the mRNA expression of inflammatory cytokines such as IL-6, IL-1β, and TNF-α in the nasal mucosa. Furthermore, THP5 inhibited Th17 cell differentiation while promoting Treg cell differentiation, accompanied by significant downregulation of JAK2-STAT3 signaling activation. Consistently, in an OVA-induced RAW264.7 and BMDMs cell model in vitro, THP5 similarly attenuated inflammatory cytokine production and diminished JAK2-STAT3 pathway activation. In conclusion, as a natural plant polysaccharide, the therapeutic effect of nebulized THP5 in alleviating AR is achieved through a multi-target mechanism involving suppression of pro-inflammatory cytokines and modulation of Th17 cell differentiation, potentially mediated via JAK2-STAT3 signaling activation. These findings highlight THP5 as a promising candidate for the treatment of AR.