Senecio scandens extract alleviates allergic rhinitis by attenuating epithelial inflammation and modulating gut microbiota balance

Background: Senecio scandens Buch.-Ham. ex D.Don (SS) has a history of use in traditional Chinese medicine for the treatment of inflammatory allergic conditions, including allergic rhinitis (AR), although its precise mechanisms of action remain unclear. Objective: This study aims to reveal the effect and the underlying mechanism of SS on treating AR. Materials and methods: An in vivo AR model was established via ovalbumin (OVA) sensitization and challenge. The therapeutic effects of SS were assessed by evaluating symptom scores (sneezing, scratching), nasal mucosal pathology, and inflammatory factor expression. The composition of the intestinal microbiota was analyzed by 16S rRNA sequencing. In vitro nasal epithelial cells inflammation was induced to verify the direct anti-inflammatory effects of SS and the role of short-chain fatty acids. Results: SS treatment significantly alleviated AR symptoms, both eosinophil infiltration and goblet cell hyperplasia in the nasal mucosa were reduced, and lowered levels of key inflammatory factors. It directly suppressed the expression of epithelial-derived alarmins in vitro . Furthermore, SS restored gut microbiota diversity and normalized the perturbed profile of Bacteroidota and Firmicutes, which are critically involved in the potential regulation of SCFA metabolism. The microbial metabolite butyrate was verified to inhibit inflammatory response in nasal epithelial cells in vitro , suggesting that the therapeutic effect of SS may be partially associated with gut microbiota-related SCFA metabolic regulation. Conclusion: This study demonstrates that SS may alleviate AR potentially through a dual mechanism: direct suppression of nasal epithelial inflammation and modulation of the gut microbiota and its associated SCFA metabolism.