Induction of cytochrome P450 1A by cow milk-based formula: a comparative study between human milk and formula

Area of Science:

• Pharmacology and Toxicology
• Biochemistry
• Neonatal Medicine

Background:

• Neonatal apnea treatment involves caffeine, with formula-fed infants showing faster clearance than breastfed infants.
• Human milk contains environmental pollutants that are potent inducers of cytochrome P450 1A (CYP1A), seemingly contradicting observed caffeine metabolism differences.

Purpose of the Study:

• To investigate the mechanisms behind differential caffeine metabolism in formula-fed versus breastfed infants.
• To characterize the induction of CYP1A and CYP3A4 by human milk and infant formula.

Main Methods:

• HepG2 cells were used to assess mRNA and protein expression of CYP1A1/1A2 and CYP3A4.
• Luciferase reporter assays evaluated aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR) activation.
• Experiments included cotreatment with an AhR antagonist and activation with a known AhR agonist.

Main Results:

• Cow milk-based infant formula significantly induced CYP1A1/1A2 mRNA and protein expression in HepG2 cells, while human milk did not.
• Infant formula activated the AhR pathway, whereas human milk did not.
• AhR activation by a potent agonist was suppressed by both infant formula and human milk.
• CYP3A4 expression and PXR activation were only mildly affected by both formula and human milk.

Conclusions:

• Infant formula, not human milk, enhances CYP1A expression in vitro via an AhR-mediated pathway.
• This AhR-dependent induction by formula provides a potential explanation for increased caffeine elimination in formula-fed neonates.
• The findings highlight differences in how infant nutrition impacts drug-metabolizing enzyme activity.