Type I interferons protect neonates from acute inflammation through interleukin 10-producing B cells

Area of Science:

• Immunology
• Neonatal immunology

Background:

• Newborns and infants exhibit heightened susceptibility to infections, with underlying immune mechanisms not fully elucidated.
• Understanding neonatal immune responses is critical for managing infections and inflammatory conditions in early life.

Purpose of the Study:

• To investigate the role of neonatal B cells in regulating inflammatory responses mediated by Toll-like receptors (TLRs).
• To elucidate the mechanisms by which neonatal B cells control cytokine production and influence susceptibility to infection.

Main Methods:

• Utilized neonatal mouse models to study B cell function after TLR triggering with various agonists (e.g., CpG, Pam3CSK4, lipopolysaccharide, R848).
• Assessed cytokine production (e.g., IL-10, IFN-alpha/beta) and inflammatory responses in the presence or absence of B cells and specific B cell subsets.
• Investigated the impact of type I interferons (IFNs) on neonatal B cell function and inflammatory control.

Main Results:

• Neonatal B cells suppress proinflammatory cytokine production by dendritic cells in an IL-10-dependent manner following TLR9 activation.
• Absence of B cells or CD5+ B cell subsets in neonatal mice leads to exacerbated inflammatory responses and lethal susceptibility to CpG challenge.
• Type I IFNs enhance IL-10 secretion by neonatal B cells, promoting anti-inflammatory effects and controlling acute inflammation, contrasting with their role in adult mice.

Conclusions:

• Neonatal B cells play a vital regulatory role in controlling TLR-mediated inflammation through IL-10 production.
• Type I IFNs contribute to this protective function of neonatal B cells, highlighting a unique aspect of neonatal immunity.
• These findings have significant implications for understanding and managing neonatal inflammation and infections.