D1.425 - Impact of Early Postnatal Administration of Escherichia coli O83:K24:H31 on Immune System Maturation and Gut Barrier Function

The early postnatal period is critical for immune system maturation and the establishment of host–microbiota interactions. Early microbial colonization influences immune tolerance and intestinal barrier development. Probiotic supplementation during this period may modulate immune responses and provide long-term protection against inflammatory diseases. This study evaluated the effects of early postnatal administration of Escherichia coliO83:K24:H31 on immune maturation, gut barrier function, and susceptibility to intestinal inflammation.

A neonatal mouse model was used to investigate the impact of early-life supplementation with E. coli O83:K24:H31. Colonization capacity in the gastrointestinal tract was assessed during the early postnatal period. The maturation and functional properties of dendritic cells were analyzed using bone marrow-derived and cord blood-derived dendritic cells. Cytokine production and T-cell polarization were evaluated by in vitro and in vivo assays. Gut barrier function was assessed by measuring intestinal permeability. In adulthood, susceptibility to inflammation was examined using a TNBS-induced colitis model, with evaluation of weight loss and macroscopic and histological disease scores.

Early postnatal administration of E. coli O83 resulted in efficient intestinal colonization and promoted dendritic cell maturation. Treated animals exhibited increased production of the immunoregulatory cytokine interleukin-10 and a shift toward a tolerogenic immune profile. Probiotic supplementation improved gut barrier integrity and reduced inflammatory responses. In the TNBS-induced colitis model, supplemented animals showed significantly reduced weight loss and lower macroscopic and histological scores compared with controls, indicating attenuated disease severity.

Early-life supplementation with E. coli O83:K24:H31 supports immune system maturation, enhances intestinal barrier function, and reduces susceptibility to inflammatory bowel disease in adulthood. These findings suggest that early probiotic intervention may represent an effective strategy for long-term modulation of immune homeostasis and prevention of immune-mediated disorders.