Can gut bacteria help shape newborn's immune system? Study sheds light

For the study, researchers analyzed neonatal mouse gut and observed that they had much higher levels of neurotransmitters, including serotonin, than the adult gut.

"So far, almost all studies of gut neurotransmitters were conducted in adult animals or human subjects, where a specific gut cell type called enterochromaffin cells produce neurotransmitters," said Dr. Zeng. "However, we discovered that this isn't the case in the newborn gut where most of the serotonin is made by bacteria that are more abundant in the neonatal gut."

The study results suggested that before the neonatal gut is mature enough to make its own neurotransmitters, unique gut bacteria may supply neurotransmitters that are needed for critical biological functions during early development.

"We found that gut bacteria in young mice not only directly produce serotonin but also decrease an enzyme called monoamine oxidase that normally breaks down serotonin, thus keeping gut serotonin levels high," said the study's lead author Dr. Katherine Sanidad, postdoctoral associate in pediatrics at Weill Cornell Medicine.

Reference:Katherine Z. Sanidad, Stephanie L. Rager, Hannah C. Carrow, Aparna Ananthanarayanan, Ryann Callaghan, Lucy R. Hart, Tingting Li, Purnima Ravisankar, Julia A. Brown, Mohammed Amir, Jenny C. Jin, Alexandria Rose Savage, Ryan Luo, Florencia MardorskyRowdo, M. Laura Martin, Randi B. Silver, Chun-Jun Guo, Jan Krumsiek, Naohiro Inohara, Melody Y. Zeng. Gut bacteria–derived serotonin promotes immune tolerance in early life. Science Immunology, 2024; 9 (93) DOI: 10.1126/sciimmunol.adj4775