Anne Donnet

Glycoproteomics of milk: Differences in sugar epitopes on human and bovine milk fat globule membranes

Oligosaccharides from human and bovine milk fat globule membranes were analyzed by LC-MS and LC-MS/MS. Global release of N-linked and O-linked oligosaccharides showed both to be highly sialylated, with bovine peak-lactating milk O-linked oligosaccharides presenting as mono- and disialylated core 1 oligosaccharides (Galbeta1-3GalNAcol), while human milk had core type 2 oligosaccharides (Galbeta1-3(GlcNAcbeta1-6)GalNAcol) with sialylation on the C-3 branch. The C-6 branch of these structures was extended with branched and unbranched N-acetyllactosamine units terminating in blood group H and Lewis type epitopes. These epitopes were also presented on the reducing terminus of the human, but not the bovine, N-linked oligosaccharides. The O-linked structures were found to be attached to the high molecular mass mucins isolated by agarose-polyacrylamide composite gel electrophoresis, where MUC1 and MUC4 were present. Analysis of bovine colostrum showed that O-linked core 2 oligosaccharides are present at the early stage (3 days after birth) but are down-regulated as lactation develops. This data indicates that human milk may provide different innate immune protection against pathogens compared to bovine milk, as evidenced by the presence of Lewis b epitope, a target for the Helicobacter pylori bacteria, on human, but not bovine, milk fat globule membrane mucins. In addition, non-mucin-type O-linked fucosylated oligosaccharides were found (NeuAc-Gal-GlcNAc1-3Fuc-ol in bovine milk and Gal-GlcNAc1-3Fuc-ol in human milk). The O-linked fucose structure in human milk is the first to our knowledge to be found on high molecular mass mucin-type molecules.

Protein quality and quantity in cow's milk-based formula for healthy term infants: past, present and future.

The development of infant formula with optimized protein quality and quantity has been, and still is, the subject of intense investigation. A better understanding of the protein composition of breast milk and infant needs in association with technological breakthroughs in cows milk fractionation, has led to the development of infant formulas with a protein content that is closer to that of human milk. Today, infant formulas with a protein/energy ratio of 1.8 g/100 kcal are commercially available. These formulas have been shown to be safe and nutritionally adequate for term infants. However, the short-term and potentially long-term metabolic benefits of formulas with reduced protein content have still to be elucidated and are currently under investigation. In addition to providing amino acids as building blocks for growth, milk is the source of numerous bioactive factors/hormones which are involved in multiple physiological processes. Continuous efforts are being made to identify new bioactive compounds in human milk. However, a better understanding of their biological functions in suckling infants as well as a comparison with their bovine counterparts are needed. Technological processes, which preserve some bioactive factors in cows milk already exist. These processes could be applied to infant formulas.

The influence of probiotic organisms on the immune response.

Mucosal surfaces represent extensive areas of interface between the host and its external environment. They are the site at which most of the host’s infectious processes begin. Physiologically, they can be relatively sterile (i.e., the distal pulmonary track) or colonized (even highly colonized), as the distal gastrointestinal tract (GIT).

How Can We Impact the Immune System with Pre- and Probiotics?

In recent years there has been a growing interest in understanding the influence of intestinal microbiota on the physiology of the body. Moreover, with the available genomic studies, it is now possible to analyze how components of the intestinal microbiota modulate features of human postnatal development and physiology [1]. An area of major interest has been the relationship between the gut bacteria and the immune system, both at the intestinal and systemic level [2]. Changes in the microbiologic content of the intestine can be induced by the administration of selected bacterial inoculums as part of a normal diet or as dietary supplements. The health-promoting microorganisms are called probiotics. The administration of specific fibers in the diet called prebiotics can also modify the intestinal ecology by promoting the growth of some particular components of the intestinal microbiota, such as bifidobacteria. On the one hand, there is an immune activation which is associated with improved mucosal defenses against pathogens and responses to oral vaccines. On the other, a modified immune reactivity which preserves homeostasis in mucosal tissues confronted with a constantly changing environment. Not only does the latter avoid an excessive reaction and inflammatory damage in the local environment, it also influences the homeostasis of the systemic immune system and prevents the development of allergic or autoimmune diseases. It is difficult to provide a simple mechanistic explanation for the underlying cellular and molecular events that support these apparently opposing effects. However, a brief overview of the evolving models that have been postulated to explain basic immune function, may help us understand how intestinal bacteria effect the mucosal and systemic immune systems [3, 4]. The most important of these are the following. Lochs H, Thomas DR (eds): Home Care Enteral Feeding. Nestlé Nutrition Workshop Series Clinical & Performance Program, vol 10, pp 203–217, Nestec Ltd., Vevey/S. Karger AG, Basel,