Time-Dependent Differences in the Human Milk Proteome After Preterm Birth: A Paired Two-Stage Proteomic Study

Area of Science:

• Human milk proteomics
• Infant nutrition
• Lactation biology

Background:

• Human milk composition varies with gestational age and lactation stage.
• Proteomic differences between milk from mothers of preterm and term infants are not fully understood.
• Temporal patterns of these proteomic differences require further characterization.

Purpose of the Study:

• To characterize proteomic differences in human milk between mothers of preterm and term infants.
• To investigate the temporal patterns of these protein differences during early and later lactation.
• To identify key proteins and functional categories affected by infant prematurity.

Main Methods:

• Prospective study of 40 lactating mothers (20 preterm, 20 term infants).
• Milk samples collected in early (postpartum days 1-10) and later (week 5) lactation.
• Quantitative data-independent acquisition mass spectrometry and Gene Ontology analysis.

Main Results:

• 662 proteins identified per sample on average; 169 consistently quantified.
• Early lactation: 10 differentially abundant proteins. Later lactation: 19 differentially abundant proteins, mostly higher in preterm milk.
• Immune-related proteins were prominent; immunoglobulin heavy constant gamma 4 was downregulated in preterm milk, while calprotectin subunits were upregulated later.

Conclusions:

• Proteomic profiles of human milk differ significantly between preterm and term infants.
• Lactation stage is a critical factor influencing these proteomic differences.
• Specific proteins, particularly immune-related ones, show dynamic changes throughout lactation in response to infant prematurity.