Neutrophil and endothelial adhesive function during human fetal ontogeny

Area of Science:

• Immunology
• Neonatalogy
• Developmental Biology

Background:

• Neonatal infections pose a significant threat, especially to premature infants, due to an attenuated immune response.
• While innate immunity in mature neonates is increasingly understood, the developmental trajectory of neutrophil recruitment remains largely unknown.

Purpose of the Study:

• To investigate the ontogeny of neutrophil recruitment and endothelial cell (EC) adhesion functions during gestation.
• To understand how gestational age impacts neutrophil and EC interactions relevant to immune defense.

Main Methods:

• Utilized microflow chambers to assess neutrophil rolling and adhesion functions in relation to gestational age.
• Analyzed the expression of PSGL-1, Mac-1, E-selectin, and ICAM-1 on neutrophils and ECs from infants of varying gestational ages.
• Monitored postnatal neutrophil function to compare with intrauterine development.

Main Results:

• Neutrophil adhesion and rolling capabilities directly correlate with gestational age, being significantly reduced in extremely premature infants (<30 weeks).
• Reduced expression of PSGL-1 and Mac-1 on neutrophils from preterm infants was observed.
• Endothelial cells (ECs) from premature infants showed diminished capacity to mediate neutrophil adhesion and reduced upregulation of E-selectin and ICAM-1.
• Neutrophil recruitment maturation occurs similarly during both intrauterine and postnatal development.

Conclusions:

• Neutrophil recruitment and EC adhesion functions are developmentally regulated in the fetus.
• The ontogenetic regulation of these immune functions may significantly contribute to the high susceptibility to life-threatening infections in premature infants.