Early-life microbiota direct an epithelial S100 program required for neonatal immunity.

Summary

Using neonatal mouse models, this study identified commensal microbiota exposure at birth as a trigger for intestinal epithelial S100A8/S100A9 calprotectin production. Loss of microbiota colonization or calprotectin expression increased susceptibility to sepsis and death, whereas exogenous calprotectin rescued microbiota-depleted pups, providing a causal link between early microbial colonization and neonatal antimicrobial defense.

Key Findings

• Initial commensal microbiota exposure induced S100A9 expression and calprotectin production by neonatal intestinal epithelial cells.
• Impaired microbiota colonization or calprotectin expression increased neonatal susceptibility to sepsis and postinfection death.
• Calprotectin administration rescued microbiota-depleted neonatal mice from lethal infection.

Clinical Implications

The findings support investigation of microbiota-preserving strategies, epithelial antimicrobial supplementation, or calprotectin-based interventions for high-risk neonates. Translation requires confirmation in human neonates and careful assessment of developmental safety, dosing, and effects on microbiome composition.

Limitations

• The principal mechanistic evidence was generated in neonatal mice, and species differences may limit direct translation to human infants.
• The provided abstract does not report the complete cohort size, duration of follow-up, or detailed dose-response and safety data for calprotectin administration.

Future Directions

Future studies should validate the epithelial S100–calprotectin pathway in human neonatal tissues and prospective infant cohorts, define the responsible microbial taxa and metabolites, and test microbiota-based or calprotectin-based interventions in carefully controlled translational models.