Effect of amnionitis on the complement system of preterm infants

Area of Science:

• Immunology
• Neonatal Medicine
• Developmental Biology

Background:

• The complement system is crucial for immune defense but its development in utero and early infancy is not fully understood.
• Understanding complement development is vital for assessing neonatal immune status and susceptibility to infection.

Purpose of the Study:

• To investigate the developmental trajectory of the complement system in human fetuses and neonates.
• To analyze complement component levels in relation to gestational age and neonatal illnesses, particularly amnionitis.

Main Methods:

• Quantitation of total hemolytic complement activity (CH50), C1q, C3, C4, and C3d in cord plasma.
• Analysis of complement levels in relation to gestational age, placental histology (amnionitis), and neonatal conditions like Wilson-Mikity syndrome and respiratory distress syndrome.

Main Results:

• Complement levels showed significant correlations with gestational age in neonates without amnionitis.
• In cases of amnionitis, complement system activation was observed even in fetuses less than 28 weeks gestation.
• Complement levels correlated with placental inflammation, except for C1q, and were elevated in Wilson-Mikity syndrome compared to respiratory distress syndrome.

Conclusions:

• The complement system undergoes significant development during gestation, influenced by intrauterine environment.
• Amnionitis triggers early complement activation, indicating a heightened inflammatory response in preterm neonates.
• Complement profiles can differentiate between certain neonatal respiratory conditions and are linked to the extent of placental inflammation.