Elevated Th17 response in infants undergoing respiratory viral infection

Area of Science:

• Immunology
• Pediatrics
• Virology

Background:

• Interleukin-17 (IL-17) and T-helper 17 (Th17) cells are implicated in viral airway pathology in newborns.
• Umbilical cord blood T cells typically fail to differentiate into Th17 cells with autologous antigen-presenting cells.

Purpose of the Study:

• To investigate the presence and role of Th17 cells in young infants experiencing respiratory viral infections, specifically respiratory syncytial virus (RSV).

Main Methods:

• Analysis of tracheal aspirate samples from infants with acute RSV infection and healthy infant controls.
• Assessment of IL-17 levels, CD161(+) T cell accumulation, and Th17-polarizing cytokines.
• Investigation of Th17 cell generation by infant dendritic cells (DCs) upon TLR4 and TLR7 stimulation.

Main Results:

• Acute RSV infection in infants is associated with elevated IL-17 and increased CD161(+) T cells in the airways.
• Th17 cells are absent in healthy 1-month-old infants but detected in infants with acute RSV.
• Pathogen-associated pattern receptor triggering of infant DCs promotes a Th17-polarizing cytokine environment.

Conclusions:

• Th17 cells are absent in healthy newborns but are present in the peripheral blood and airways of infants with viral infections.
• The emergence of Th17 cells during RSV infection contributes to airway immunopathology in infants.