Effect of Bacillus subtilis strain Z15 secondary metabolites on immune function in mice

Previous studies have shown that secondary metabolites of Bacillus subtilis strain Z15 (BS-Z15) are effective in treating fungal infections in mice. To evaluate whether it also modulates immune function in mice to exert antifungal effects, we investigated the effect of BS-Z15 secondary metabolites on both the innate and adaptive immune functions of mice, and explored its molecular mechanism through blood transcriptome analysis. The study showed that BS-Z15 secondary metabolites increased the number of monocytes and platelets in the blood, improved NK cell activity and phagocytosis of monocytes-macrophages, increased the conversion rate of lymphocytes in the spleen, the number of T lymphocytes and the antibody production capacity of mice, and increased plasma levels of IFN-γ, IL-6, IgG and IgM. The blood transcriptome analysis revealed 608 differentially expressed genes following treatment with BS-Z15 secondary metabolites, all of which were significantly enriched in the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms for immune-related entries and pathways such as TNF and TLR signaling pathways, and upregulated expression levels of immune-related genes such as C1qb, C4b, TCR and RFX5. BS-Z15 secondary metabolites were shown to enhance innate and adaptive immune function in mice, laying a theoretical foundation for its development and application in the field of immunity.