(8) Perinatal Antibiotic Exposure Alters Goblet Cell-associated Antigen Passage Regulation in Neonatal Mice

Background: The connection between infection and premature birth is vital since it affects the postnatal health of premature infants. Many extremely low birthweight infants face prenatal and postnatal infections, leading to antibiotic exposure during the perinatal period. While necessary for treating early-onset sepsis (EOS), antibiotic exposure in the first week raises the risk of late-onset sepsis (LOS), necrotizing enterocolitis (NEC), and death in extremely premature infants. These complications may arise from a weakened intestinal barrier function. Intestinal goblet cell-associated antigen passages (GAPs) allow the immune system to interact with luminal antigens, fostering tolerogenic responses. Maternal transfer of epidermal growth factor (EGF) via breast milk inhibits intestinal GAPs through the EGF receptor. Our lab shows that open GAPs in the neonatal period correlate with a higher risk of death in a murine model of LOS. It remains unknown how early-life antibiotics affect GAP regulation in neonatal mice.

Objectives: We hypothesize that perinatal antibiotic exposure causes precocious opening of GAPS in neonatal mice.

Design/Methods: We have developed an early-life antibiotic exposure model for mice that treats the SPF-housed C57BL/6 dams with neomycin and ampicillin for 7 days, starting on pup postnatal day (P) 1. The pups are euthanized on P8. Small and large intestines, stool, and blood were collected for evaluation. GAPS were labeled by injecting 10 kDa rhodamine dextran into the lumen of isolated small intestinal and colonic segments. Segments were incubated for 20 min at 37 °C before fixation.

Results: Our findings indicate that pups exposed to antibiotics during early life show impaired growth and impaired intestinal barrier function. H&E staining revealed epithelial damage and alterations in villi architecture in antibiotic-exposed mice compared to controls. When pups were exposed to antibiotics in early life, they were found to have significantly more GAPS in the small intestine compared to controls. Next, we quantified EGF levels in the stomach contents (as a proxy for breast milk) and the small intestine of control and exposed pups via ELISA. There were no significant decreases in EGF concentration in the antibiotic-exposed pups.

Conclusions: These data suggest that antibiotic-induced GAP availability is not due to decreased breast milk's EGF levels. Our future directions include assessing concentrations of other EGFR ligands in the breast milk and intestine to assess their levels and contributions to GAP regulation in neonatal mice.