Profiling murine gut influence on peripheral tolerance

Antibiotic exposure early in life, and other practices impacting the vertical transmission and ordered assembly of a diverse and balanced gut microbiota, are associated with a higher risk of immunological and metabolic disorders such as asthma and allergy, autoimmunity, obesity, and susceptibility to opportunistic infections. Here, we use a model of perinatal exposure to the broad-spectrum antibiotic ampicillin to examine how the acquisition of a dysbiotic microbiota affects neonatal immune system development. We find that the resultant dysbiosis imprints in a manner that is irreversible after weaning, leading to specific and selective alteration of the colonic CD4+ T-cell compartment. In contrast, colonic granulocyte and myeloid lineages, and other mucosal T-cell compartments are unaffected. Amongst colonic CD4+ T-cells, we observe the most pronounced effects on neuropilin negative, Rorgt- and Foxp3-positive regulatory T-cells, which are largely absent in antibiotic-exposed mice even as they reach adulthood. Immunomagnetically isolated dendritic cells from antibioticexposed mice fail to support the generation of Foxp3+ Tregs from naïve T-cells ex vivo. The perinatally acquired dysbiotic microbiota predisposes to dysregulated effector T-cell responses to Citrobacter rodentium or ovalbumin challenge. The transfer of the antibiotic-impacted, but not healthy fecal microbiota into germ-free recipients recapitulates the selective loss of colonic neuropilin-negative, Rorgt- and Foxp3-positive Tregs. The combined data indicate that the early-life acquisition of a dysbiotic microbiota has detrimental effects on the diversity and microbial community composition of offspring that persist into adulthood, and predisposes to inappropriate T-cell responses that are linked to compromised immune tolerance.