An interactomics overview of the human and bovine milk proteome over lactation

Abstract

BackgroundMilk is the most important food for growth and development of the neonate, because of its nutrient composition and presence of many bioactive proteins. Differences between human and bovine milk in low abundant proteins have not been extensively studied. To better understand the differences between human and bovine milk, the qualitative and quantitative differences in the milk proteome as well as their changes over lactation were compared using both label-free and labelled proteomics techniques. These datasets were analysed and compared, to better understand the role of milk proteins in development of the newborn.MethodsHuman and bovine milk samples were prepared by using filter-aided sample preparation (FASP) combined with dimethyl labelling and analysed by nano LC LTQ-Orbitrap XL mass spectrometry.ResultsThe human and bovine milk proteome show similarities with regard to the distribution over biological functions, especially the dominant presence of enzymes, transport and immune-related proteins. At a quantitative level, the human and bovine milk proteome differed not only between species but also over lactation within species. Dominant enzymes that differed between species were those assisting in nutrient digestion, with bile salt-activated lipase being abundant in human milk and pancreatic ribonuclease being abundant in bovine milk. As lactation advances, immune-related proteins decreased slower in human milk compared to bovine milk. Notwithstanding these quantitative differences, analysis of human and bovine co-expression networks and protein-protein interaction networks indicated that a subset of milk proteins displayed highly similar interactions in each of the different networks, which may be related to the general importance of milk in nutrition and healthy development of the newborn.ConclusionsOur findings promote a better understanding of the differences and similarities in dynamics of human and bovine milk proteins, thereby also providing guidance for further improvement of infant formula.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-016-0110-0) contains supplementary material, which is available to authorized users.

Protective factors in mature human milk: a look into the proteome and peptidome of adolescent mothers’ breast milk

“…These proteins play important roles in the immune system, especially the innate immune system. In particular, SERPINA1 protects the proteins related to the immune system from degradation during digestion (36)(37)(38) .…”

“…Analysis of the early mature milk group showed the presence of CD14 peptides that are related to the immune system. Lipopolysaccharide binding protein binds to monomeric lipopolysaccharide and delivers it to the LY96/TLR4 complex, thereby mediating the immune response to bacterial lipopolysaccharide (38) . These results show that milk components, especially those of skimmed early mature breast milk, participate in the innate and adaptive immunity, thereby conferring immune defence to the newborn.…”

“…Another important function of MFGE8 is to bind to rotaviruses and inhibit their replication (39) . SPP1 has also been associated with inflammatory processes (38) . The GAPDH protein is a key regulator of energy metabolism and has additionally been reported as being essential for the maintenance of normal secretory function; it is a multifunctional protein in mammalian cells, and it may influence the activity of other proteins (40,41) .…”

The Impact of Dietary Fucosylated Oligosaccharides and Glycoproteins of Human Milk on Infant Well-Being

“…In the context of mixtures based on cow's milk, differences regarding not only oligosaccharides and proteins but also the glycosylation profile of milk glycoproteins should be taken into consideration [165,166]. The comparison of the N-glycan pattern of the whey milk fraction [167] and milk fat globule membrane [168] of both human and bovine colostrum and mature milk elicited significant qualitative and quantitative differences and the N-glycosylation profile was strongly affected by the stage of lactation.…”

Lactic acid‐mediated isolation of alpha‐, beta‐ and kappa‐casein fractions by isoelectric precipitation coupled with cold extraction from defatted cow milk

“…Milk is considered as a complete or ultimate food for mammals, as it contains rich proteins (20% casein and 80% whey protein), fat, minerals and vitamins. It also serves as a potential source of bioactive peptides (Korhonen and Pihlanto ; Nielsen et al ; Zhang et al ). Casein is a hydrophobic, thermostable (62–71 ºC) and serine‐rich phosphoprotein with limited alpha‐helix and beta‐sheet structure.…”