title: Changes over lactation in breast milk serum proteins involved in the maturation of immune and digestive system of the infant.
abstract: To objective of this study was to better understand the biological functions of breast milk proteins in relation to the growth and development of infants over the first six months of life. Breast milk samples from four individual women collected at seven time points in the first six months after delivery were analyzed by filter aided sample preparation and dimethyl labeling combined with liquid chromatography tandem mass spectrometry. A total of 247 and 200 milk serum proteins were identified and quantified, respectively. The milk serum proteome showed a high similarity (80% overlap) on the qualitative level between women and over lactation. The quantitative changes in milk serum proteins were mainly caused by three groups of proteins, enzymes, and transport and immunity proteins. Of these 21 significantly changed proteins, 30% were transport proteins, such as serum albumin and fatty acid binding protein, which are both involved in transporting nutrients to the infant. The decrease of the enzyme bile salt-activated lipase as well as the immunity proteins immunoglobulins and lactoferrin coincide with the gradual maturation of the digestive and immune system of infants. The human milk serum proteome didn't differ qualitatively but it did quantitatively, both between mothers and as lactation advanced. The changes of the breast milk serum proteome over lactation corresponded with the development of the digestive and immune system of infants.
  
  
  
  Breast milk proteins provide nutrition, but also contribute to healthy development of infants. Despite the previously reported large number of identified breast milk proteins and their changes over lactation, less is known on the changes of these proteins in individual mothers. This study is the first to determine the qualitative and quantitative changes of milk proteome over lactation between individual mothers. The results indicate that the differences in the milk proteome between individual mothers are more related to the quantitative level than qualitative level. The correlation between the changes of milk proteins and the gradual maturation of the gastrointestinal tract and immune system in infants, contributes to a better understanding of the biological functions of human milk proteins for the growth and development of infants.
authors.affiliation: Dairy Science and Technology, Food Quality and Design Group, Wageningen University, The Netherlands. Electronic address: lina.zhang@wur.nl.
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Paediatrics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marita
authors.initials: M
authors.lastname: de Waard
authors.affiliation: Department of Paediatrics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Hester
authors.initials: H
authors.lastname: Verheijen
authors.affiliation: Laboratory of Biochemistry, Wageningen University, The Netherlands.
authors.forename: Sjef
authors.initials: S
authors.lastname: Boeren
authors.affiliation: Biometris-Applied Statistics, Wageningen University, The Netherlands; Centre for BioSystems Genomics, Wageningen University, The Netherlands.
authors.forename: Jos A
authors.initials: JA
authors.lastname: Hageman
authors.affiliation: Dairy Science and Technology, Food Quality and Design Group, Wageningen University, The Netherlands.
authors.forename: Toon
authors.initials: T
authors.lastname: van Hooijdonk
authors.affiliation: Laboratory of Biochemistry, Wageningen University, The Netherlands.
authors.forename: Jacques
authors.initials: J
authors.lastname: Vervoort
authors.affiliation: Department of Paediatrics, VU University Medical Center, Amsterdam, The Netherlands; Academic Medical Center, Emma Children's Hospital, Amsterdam, The Netherlands.
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Goudoever
authors.affiliation: Dairy Science and Technology, Food Quality and Design Group, Wageningen University, The Netherlands. Electronic address: kasper.hettinga@wur.nl.
authors.forename: Kasper
authors.initials: K
authors.lastname: Hettinga
mesh_terms: D000328:Adult; D001942:Breast Feeding; D002853:Chromatography, Liquid; D004064:Digestive System; D005260:Female; D006801:Humans; D007107:Immune System / Q000502:physiology; D007223:Infant; D007231:Infant, Newborn; D007774:Lactation / Q000378:metabolism*; D008894:Milk Proteins / Q000032:analysis*; D020543:Proteome / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D008894:Milk Proteins; D020543:Proteome
keywords: Gastrointestinal tract; Immune system; Milk serum proteome; Protease inhibitors