Neonatal acquisition of Clostridia species protects against colonization by bacterial pathogens

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Neonates exhibit high susceptibility to infections, often attributed to an immature immune system.
• The precise mechanisms underlying this vulnerability and the role of the gut microbiota remain incompletely understood.

Purpose of the Study:

• To investigate the role of the gut microbiota composition in neonatal colonization resistance against bacterial pathogens.
• To identify specific bacterial taxa responsible for protection in early life.

Main Methods:

• Colonization of adult germ-free mice with neonatal and adult mouse cecal microbiota.
• Challenging colonized mice with specific bacterial pathogens known to cause neonatal mortality.
• Administering specific bacterial orders (Clostridiales, Bacteroidales) to assess protective effects.
• Depleting Clostridiales in adult mice to evaluate its necessity for colonization resistance.

Main Results:

• Neonatal microbiota failed to prevent pathogen colonization, unlike adult microbiota.
• Absence of Clostridiales in neonatal microbiota correlated with lack of colonization resistance.
• Administration of Clostridiales, but not Bacteroidales, protected neonatal mice from infection and reduced intestinal pathology.
• Depletion of Clostridiales in adult mice abolished their colonization resistance.
• Neonatal gut bacteria promoted the colonization of protective Clostridiales.

Conclusions:

• The gut microbiota plays a critical role in neonatal colonization resistance, independent of immune system maturity.
• Clostridiales are essential for establishing colonization resistance in both neonatal and adult mice.
• Targeted administration of Clostridiales may offer a therapeutic strategy to prevent or treat neonatal infections.