Developmental Immaturity of Siglec Receptor Expression on Neonatal Alveolar Macrophages Predisposes to Severe Group B Streptococcal Infection

IScience
Sean J LundLawrence S Prince

Abstract

Streptococcus agalactiae (Group B Streptococcus, GBS) is the most common neonatal pathogen. However, the cellular and molecular mechanisms for neonatal susceptibility to GBS pneumonia and sepsis are incompletely understood. Here we optimized a mouse model of GBS pneumonia to test the role of alveolar macrophage (ΑΜΦ) maturation in host vulnerability to disease. Compared with juvenile and adult mice, neonatal mice infected with GBS had increased mortality and persistence of lung injury. In addition, neonatal mice were defective in GBS phagocytosis and killing. ΑΜΦ depletion and disruption of ΑΜΦ differentiation in Csf2-/- mice both impaired GBS clearance. AMΦ engage the heavily sialylated GBS capsule via the cell surface Siglec receptors Sn and Siglec-E. Although both newborn and adult ΑΜΦ expressed Siglec-E, newborn ΑΜΦ expressed significantly lower levels of Sn. We propose that a developmental delay in Sn expression on ΑΜΦ may prevent effective killing and clearing of GBS from the newborn lung.

Citations

Sep 9, 2021·International Reviews of Immunology·Shane PrenzlerThomas Haselhorst
Oct 14, 2021·American Journal of Respiratory Cell and Molecular Biology·Umar SalimiVenkatesh Sampath

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Methods Mentioned

BETA
PCR
Flow cytometry
FACS

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