Protein and Lipid Content of Milk Extracellular Vesicles: A Comparative Overview

Abstract

The characterization of the protein and lipid cargo of milk extracellular vesicles from different mammal species is crucial for understanding their biogenesis and biological functions, as well as for a comprehensive description of the nutritional aspects of animal milk for human diet. In fact, milk EVs have been reported to possess relevant biological effects, but the molecules/biochemical pathways underlying these effects have been poorly investigated. The biochemical characterization is an important initial step for the potential therapeutic and diagnostic use of natural or modified milk EVs. The number of studies analysing the protein and lipid composition of milk EVs is limited compared to that investigating the nucleic acid cargo. Here, we revised the literature regarding the protein and lipid content of milk EVs. Until now, most investigations have shown that the biochemical cargo of EVs is different with respect to that of other milk fractions. In addition, even if these studies derived mostly from bovine and human milk EVs, comparison between milk EVs from different animal species and milk EVs biochemical composition changes due to different factors including lactation stages and health status is also beginning to be reported.

Study on the preparation of bovine milk exosomes and the stability of lyophilized powder

“…It can be added to products without heat treatment processes. AndMK-exo are rich in milk fat globule membrane (MFGM) proteins and other nutrients (Reinhardt et al 2012, Buratta et al 2023, so adding lyophilized MK-exo to milk powder can help babies develop their brains. Adding it to health supplements can improve the body's metabolic pattern, strengthen immune function, and improve intestinal flora.…”

Advances in separation and identification of biologically important milk proteins and peptides

“…Milk contains high amount of EVs [19,[56][57][58][59], which are the nanoparticles enclosed by phospholipids bilayers. EVs are naturally secreted by all cell types into extracellular space and in addition to milk, they can be found in cell cultures and various body fluids, such as plasma, saliva, spinal fluid, and urea.…”

“…EVs contain and carry biologically active molecules, such as RNAs, DNAs, proteins, and lipids. EVs are essential for intercellular communication and signaling, modulate a variety of biological processes [19,59,61,64,65], and play crucial roles in immunity transfer and neonate development [60,63]. Milk EVs can deliver RNA and protein cargo to recipient cells, which can be taken up by various cell types and affect their functions [61,66].…”

“…The reviews have been published about protein content of milk EVs [19] as well as other information about methodological approaches used in human small EVs proteomics [142].…”

“…In addition, milk proteins are present in various genetic/splicing variants [16] and are abundantly posttranslationally modified [17,18]. As well, milk contains extracellular vesicles (EVs) of various sizes which carry, in addition to other bioactive components, their own specific proteome cargo [19][20][21]. EVs have distinct roles in biological processes and they are involved in activities crucial for cell-cell communication.…”