Influence of Gestational Age on the Level of Functional Peptides (Peptidome) in Breast Milk

Human milk provides essential nutrients and immune factors with beneficial impact on term, but especially preterm infants' development. Therefore, this study focuses on the quantification of differences in the peptidome composition of breast milk from mothers of preterm and term infants, keeping in mind that this could reflect different biological needs of these infants or indicate nutritional gaps for healthy development.

In a prospective observational study, breast milk samples were collected from 10 mothers of preterm infants (29-36 weeks gestational age,) and 13 mothers of term infants (37-41 weeks) at day 4 to 6 postnatally. A non-targeted tandem mass spectrometry approach was employed to analyze the milk peptidome.

In total, 4570 peptides were quantified. Adjusting the results for maternal age, weight, and height revealed a significant difference for 130 peptides derived from 19 different proteins between preterm and term milk. Proteins comprised high abundant proteins (e.g., α_S1-casein, κ- casein, or ß-casein), but also proteins that are less prominent in milk but of high functional importance (e.g., Hypoxia-inducible factor 1-alpha, Olfactory receptor 4M1). The differentially abundant peptides included peptides derived from ß-casein, which have already been described as being involved in antimicrobial functions as well as proliferation stimulating. For another 32 peptides, bioactivity was predicted.

The current study provides a comprehensive overview on the differences in the milk peptidome at different gestational ages independent from common maternal phenotypes and improved the database for future peptide functionality studies.