Streptococcus agalactiae and Escherichia coli induce distinct effector γδ T cell responses during neonatal sepsis

Area of Science:

• Immunology
• Neonatal Research
• Microbiology

Background:

• Premature neonates are highly susceptible to life-threatening bacterial sepsis.
• Streptococcus agalactiae (GBS) and Escherichia coli are common causes of neonatal sepsis.
• The differential immune responses to these pathogens in neonates are not well understood.

Purpose of the Study:

• To investigate if GBS and E. coli induce distinct immune responses in neonatal sepsis.
• To characterize the role of gamma delta T cells in neonatal responses to GBS and E. coli.
• To determine the impact of these differential responses on neonatal neuroinflammation.

Main Methods:

• Utilized a neonatal mouse model of bloodstream infection with single organisms (GBS or E. coli).
• Analyzed gamma delta T cell responses, including cytokine production (IFN-γ and IL-17).
• Investigated the involvement of gamma delta T cell receptor (γδTCR) signaling in effector responses.

Main Results:

• Gamma delta T cells rapidly responded to both GBS and E. coli infections in neonatal mice.
• GBS infection induced IFN-γ production from gamma delta T cells, while E. coli induced IL-17.
• IL-17 production was dependent on γδTCR signaling during E. coli infection, whereas IFN-γ production during GBS infection was independent of γδTCR signaling.
• Distinct gamma delta T cell effector responses resulted in unique neuroinflammatory phenotypes in the neonatal brain.

Conclusions:

• The neonatal adaptive immune system mounts differential responses to distinct bacterial pathogens like GBS and E. coli.
• Gamma delta T cells play a crucial role in these differential responses, producing distinct cytokines.
• These pathogen-specific immune responses lead to unique patterns of neuroinflammation in the neonatal brain, highlighting the complexity of neonatal sepsis.