Effect of Bacillus Subtilis BN Strain on M1 Macrophage Antiviral Response

Area of Science:

• Immunology
• Microbiology
• Molecular Biology

Background:

• M1 macrophages are crucial in combating pathogenic microorganism infections.
• Natto, a fermented soybean food, is traditionally recognized for its infection-preventive properties.
• Bacillus subtilis BN strain, isolated from natto, is a known probiotic for gut health and immune modulation.

Purpose of the Study:

• To investigate the impact of Bacillus subtilis BN strain on the antiviral immune function of human M1 macrophages.
• To elucidate the molecular mechanisms underlying the immunomodulatory effects of the BN strain.

Main Methods:

• Human M1 macrophages were derived from the THP-1 monocytic cell line.
• Cells were treated with Bacillus subtilis BN strain, with or without resiquimod stimulation, in a model mimicking single-stranded RNA virus infection.
• Gene expression analysis of cytokines and key signaling molecules, including toll-like receptor pathway components and NFκB, was performed.
• NFκB knockdown was utilized to assess its role in BN strain-induced cytokine expression.

Main Results:

• Bacillus subtilis BN strain significantly enhanced the gene expression of antiviral and anti-inflammatory cytokines in M1 macrophages.
• The BN strain promoted gene expression and phosphorylation of key molecules within toll-like receptor signaling pathways.
• Knockdown of NFκB reduced the BN strain-induced expression of certain cytokine mRNAs, indicating its involvement.

Conclusions:

• Bacillus subtilis BN strain exhibits potent antiviral and anti-inflammatory effects on human M1 macrophages.
• Toll-like receptor signaling pathways are implicated in mediating the immunomodulatory actions of the BN strain.
• The findings support the potential of Bacillus subtilis BN strain as a probiotic for enhancing innate antiviral immunity.