Effects of synbiotic Pediococcus sp. KB1 and red perilla leaves on alleviation of allergic inflammation associated with alterations in gut microbiota in murine cedar pollinosis

Aim: Lactic acid bacteria are widely recognized for their health-promoting effects, including allergy prevention and immune activation through gut microbiota modulation. Red perilla leaves possess anti-inflammatory properties and are rich in polyphenols and dietary fibers, exerting prebiotic effects. However, the combined effects of lactic acid bacteria and red perilla leaf extract (RPE) on Japanese cedar pollinosis (JCP) have not been fully elucidated. Therefore, this study investigated the effects of the combined of Pediococcus sp. KB1 (KB1) and RPE, and their anti-inflammatory effects associated with gut microbiota modulation in a JCP mouse model. Methods: A JCP mouse model was established using 5-week-old BALB/c mice sensitized with cedar pollen extract 1 (Cry j1) and aluminum hydroxide. Mice were divided into five groups: Sham, Control, KB1, RPE, and KB1 with RPE. Sneezing and nasal rubbing were evaluated on the final day. Serum IgE and cytokines were measured by ELISA, and splenic mRNA expression was analyzed by RT-qPCR. Gut microbiota was analyzed using 16S rRNA gene sequencing with QIIME 2. Results: Combined KB1 and RPE significantly suppressed sneezing and nasal rubbing in JCP mice. The combination reduced serum IgE. Compared with single treatments, the KB1 with RPE group showed increased IL-10 and IL-27 levels in serum and splenic mRNA expression. In addition, gut microbiota composition was altered, with increased butyrate-producing bacteria such as Lachnospiraceae and Oscillospirales and decreased inflammation-associated bacteria including Enterorhabdus, Bacteroides, and Gastranaerophilales. Fecal pH was also reduced in the combination group. Conclusions: Combined administration of KB1 and RPE was suggested to alleviate Cry j1-induced pollinosis symptoms and was associated with increased serum IL-10 levels and improved gut microbiota composition, including increased butyrate-producing bacteria. These findings suggest that lactic acid bacteria combined with RPE may serve as a complementary approach for cedar pollinosis management.