Probiotic Lactobacillus Strains Stimulate the Inflammatory Response and Activate Human Macrophages

Area of Science:

• Immunology
• Microbiology
• Probiotics

Background:

• Lactobacilli are known for their health-promoting properties.
• Understanding their impact on innate immunity is crucial for harnessing their therapeutic potential.

Purpose of the Study:

• To investigate the immunomodulatory mechanisms of four specific Lactobacillus strains.
• To analyze their effects on reactive oxygen species (ROS), cytokine profiles, phagocytosis, bactericidal activity, NF-κB signaling, and TLR2 activation.

Main Methods:

• Treatment of human macrophages with four Lactobacillus strains: L. rhamnosus GG, L. rhamnosus KLSD, L. helveticus IMAU70129, and L. casei IMAU60214.
• Assays to measure ROS production, cytokine expression (IL-8, TNF-α, IL-12p70, IL-6, IL-1β), phagocytosis, bactericidal activity, NF-κB pp65 translocation, and TLR2 activation.

Main Results:

• ROS production varied based on Lactobacillus species and concentration.
• Probiotic strains induced early pro-inflammatory cytokines (IL-8, TNF-α, IL-12p70, IL-6).
• L. helveticus and L. casei specifically induced IL-1β after 24h.
• Enhanced macrophage phagocytosis and bactericidal activity against S. aureus, S. typhimurium, and E. coli.
• Increased NF-κB pp65 nuclear translocation and TLR2-dependent signaling.

Conclusions:

• Lactobacillus probiotic strains demonstrate early immunostimulatory effects on human macrophages.
• These effects are linked to the initial inflammatory response, suggesting a role in modulating innate immunity.