Matcha alleviates sneezing response in a murine model of allergic rhinitis

Matcha, a traditional Japanese tea, has been implicated in various health effects. Herein, we investigated the impact of Matcha on allergic rhinitis by employing an allergen-induced nasal inflammation model in mice. Allergen-induced immediate nasal response, represented by the evocation of sneezing in ovalbumin-immunized mice, and subsequent nasal hyperresponsiveness, assessed by enhanced histamine-triggered sneezes, were significantly suppressed by continuous intragastric administration of hot water-extracted Matcha (250 mg/kg) with its residue. However, accumulation of inflammatory cells, total and allergen-specific IgE production, and intestinal microbiota diversity were unaffected by Matcha. Histamine- and substance P-triggered sneezes, accompanied by c-Fos expression in relevant neurons, tended to be suppressed by Matcha, whereas anti-dinitrophenyl IgE-evoked passive cutaneous anaphylaxis was unaffected. T cell receptor-stimulated CD4⁺ T cell proliferation was slightly enhanced by ethanol-extracted Matcha. Accordingly, RNA-seq analysis demonstrated weak but significant upregulation of iron uptake- and proliferation-related genes in CD4⁺ T cells. Importantly, Matcha treatment nearly abolished histamine-induced c-Fos expression in the ventral spinal trigeminal nucleus caudalis (Sp5C), reducing it to basal levels, suggesting direct suppression of neural mechanisms underlying the sneezing reflex. Matcha potentially alleviates allergic rhinitis symptoms independent of IgE/mast cell- or T-cell-mediated cascades but through a direct down-regulation of the sneezing reflex.