The Respiratory Commensal Bacterium Dolosigranulum pigrum 040417 Improves the Innate Immune Response to Streptococcus...

Area of Science:

• Immunology
• Microbiology
• Respiratory Medicine

Background:

• The respiratory tract harbors commensal bacteria that can influence host immunity.
• Toll-like receptor 2 (TLR2) activation plays a role in innate immune responses to respiratory pathogens.
• Understanding the interaction between commensal bacteria and the host immune system is crucial for developing novel therapeutic strategies.

Purpose of the Study:

• To evaluate the protective effects of Dolosigranulum pigrum 040417 against Streptococcus pneumoniae infection in infant mice.
• To investigate the role of alveolar macrophages (AMs) in the immunomodulatory mechanisms of D. pigrum 040417.
• To determine if the observed immunomodulatory effects are strain-specific.

Main Methods:

• Nasal administration of D. pigrum 040417 to infant mice.
• Infection with Streptococcus pneumoniae.
• Assessment of respiratory cytokine production and lung injury.
• Depletion of alveolar macrophages (AMs) to evaluate their role.
• Comparison with a non-beneficial D. pigrum strain (030918).

Main Results:

• Nasal D. pigrum 040417 administration significantly increased resistance to pneumococcal infection.
• This protection was associated with modulated respiratory cytokine profiles and reduced lung damage.
• Alveolar macrophages (AMs) were critical for D. pigrum 040417's beneficial effects on pathogen load and lung protection.
• The immunomodulatory effects were strain-specific, with D. pigrum 030918 showing no beneficial impact.

Conclusions:

• Dolosigranulum pigrum 040417 confers protection against Streptococcus pneumoniae infection in infant mice.
• Alveolar macrophages (AMs) are key mediators of the protective and immunomodulatory effects of D. pigrum.
• These findings suggest that specific strains of D. pigrum could be developed as next-generation probiotics for respiratory health.