Decreased anti-inflammatory responses to vitamin D in neonatal neutrophils

Area of Science:

• Immunology
• Neonatal Medicine
• Endocrinology

Background:

• Neutrophil activity is prolonged in newborns.
• This suggests reduced responses to immunosuppressive factors like 1,25-dihydroxyvitamin D3 (1,25-vit D3).

Purpose of the Study:

• To investigate if 1,25-vit D3 suppresses neutrophil activation.
• To determine if this response is impaired in neonatal neutrophils.

Main Methods:

• Compared 1,25-vit D3 effects on lipopolysaccharide (LPS)-induced neutrophil activation in adult and neonatal cells.
• Measured expression of vitamin D receptor (VDR) and 1α-hydroxylase in neutrophils.
• Assessed inflammatory mediator and enzyme expression (MIP-1β, VEGF, COX-2, 5-LOX).

Main Results:

• 1,25-vit D3 decreased inflammatory markers in adult neutrophils but not neonatal ones.
• Neonatal neutrophils showed reduced VDR and 1α-hydroxylase expression.
• 1,25-vit D3 induced VDR expression in adult neutrophils, but not neonatal.
• Vitamin D insensitivity did not affect respiratory burst in either group.

Conclusions:

• Neonatal neutrophils exhibit impaired anti-inflammatory responses to 1,25-vit D3.
• Reduced VDR and 1α-hydroxylase expression likely underlies this insensitivity.
• This neonatal vitamin D insensitivity may contribute to chronic inflammation.