Allergic rhinitis (AR) has reached epidemic proportions globally, with environmental factors driving its increasing prevalence and substantial disease burden. Current pharmacotherapies often provide incomplete symptom relief while failing to address underlying immune dysfunction. Growing recognition of the gut-lung axis highlights the therapeutic potential of probiotics in modulating systemic immunity through microbial metabolites. In this randomized, double-blind, placebo-controlled trial, we investigated the efficacy of Weizmannia coagulans BC99 (2 × 10 9 CFU/day) in 78 adult AR patients (40 intervention, 38 placebo) over 8 weeks. Comprehensive assessments included validated symptom metrics (VAS, TNNSS), serum biomarkers (ELISA quantification of IgE, TNF-α, IFN-γ, IL-4/5/10/13), fecal Short-chain fatty acids (SCFA) profiling (gas chromatography), and gut microbiome analysis (16S rRNA sequencing). The BC99 intervention group demonstrated significant clinical and physiological improvements with VAS and TNNSS scores ( p < 0.0001). Furthermore, BC99 supplementation significantly decreased serum IgE, TNF-α while enhancing anti-inflammatory IL-10 levels and SCFAs concentrations (all p < 0.05). Gut microbiota analysis indicated increased abundance of beneficial Prevotella alongside decreased levels of pathogenic Escherichia-Shigella (both p < 0.05). BC99 supplementation produced clinically meaningful improvements, reducing VAS (24.87 ± 7.46 to 7.74 ± 5.69) and TNNSS (3.81 ± 1.08 to 1.61 ± 1.63) scores ( p < 0.0001). The intervention effectively attenuated type 2 inflammatory markers, as evidenced by reduced IgE and TNF-α levels, while simultaneously boosting immunoregulatory IL-10 production. The intervention significantly attenuated type 2 inflammation (decrease in IgE and TNF-α) while enhancing immunoregulatory responses (increase in IL-10). Microbial metabolite analysis revealed an elevation in total SCFAs (1893.28 ± 186.85 to 2237.25 ± 535.34 mg/L). Gut microbiota profiling revealed a significant shift in bacterial composition, characterized by elevated abundance of beneficial Prevotella species and reduced levels of pathogenic Escherichia-Shigella ( p < 0.05). W. coagulans BC99 demonstrates multimodal efficacy in AR management, simultaneously improving clinical symptoms, rebalancing immune responses, and restoring gut microbial homeostasis. These findings position BC99 as a novel microbiome-targeted therapeutic for allergic airway disease. • W. coagulans BC99 gummies can alleviate clinical symptoms of allergic rhinitis in adults. • W. coagulans BC99 gummies can effectively regulate the level of inflammatory factors in the body and enhance immune regulation. • W. coagulans BC99 gummies can improve intestinal microbiota and promote the secretion of short-chain fatty acids.
Jiang et al. (Fri,) studied this question.