Stereotypic expansion of Tregulatory and Th17 cells during infancy is disrupted by HIV exposure and gut epithelial damage.

Few studies have investigated immune cell ontogeny throughout the period of increased vulnerability to infections in early life. Here, we evaluated the dynamics of two critical T cell populations, regulatory T (Treg) cells and Th17 cells, over the first 9 months of life. We observed that Treg and Th17 cells developed in a synchronous fashion. Infants exposed to HIV in utero (iHEU), who are more likely to develop infections, had a lower frequency of Tregs at birth and 36 weeks compared to HIV unexposed infants. This increased Th17/Treg ratio in iHEU was associated with impaired gut integrity at birth. These findings suggest that gut damage disrupts the Th17/Treg ratio during infant immune development, likely by attracting Treg cells to regulate inflammation occurring in the gut, so revealing an immune-gut nexus influenced by HIV exposure.