Streptococcus agalactiae and Escherichia coli Induce Distinct Effector γδ T Cell Responses During Neonatal Sepsis and Neuroinflammation

Neonates born prematurely are highly vulnerable to life-threatening conditions such as bacterial sepsis. Streptococcus agalactiae, also known as group B Streptococcus (GBS) and Escherichia coli are frequent causative pathogens of neonatal sepsis, however, it remains unclear if distinct sepsis pathogens induce differential adaptive immune responses. In the present study, we find that {gamma}{delta} T cells in neonatal mice rapidly respond to single-organism GBS and E. coli bloodstream infections and that these pathogens induce distinct activation and cytokine production from IFN-{gamma} and IL-17 producing {gamma}{delta} T cells, respectively. We also report differential reliance on {gamma}{delta}TCR signaling to elicit effector cytokine responses during neonatal sepsis, with IL-17 production during E. coli infection being driven by {gamma}{delta}TCR signaling, and IFN-{gamma} production during GBS infection occurring independently of {gamma}{delta}TCR signaling. Furthermore, we report that the divergent effector responses of {gamma}{delta} T cells during GBS and E. coli infections impart distinctive neuroinflammatory phenotypes on the neonatal brain. The present study reveals that the neonatal adaptive immune system differentially responds to distinct bacterial stimuli, resulting in unique neuroinflammatory phenotypes.