Lectin microarray profiling and monosaccharide analysis of bovine milk immunoglobulin G oligosaccharides during the first 10 days of lactation.

Immunoglobulin G (IgG) in bovine milk is credited with ensuring efficient passive immunity for newborn calves. Bovine milk IgG glycosylation may also have positive impacts on the health of nonbovine consumers of cow's milk. Milk IgG's glycosylation contributes to effector function and may also protect it from protease digestion, allowing IgG to reach the intestine for absorption. However, relatively little is known about changes in milk IgG oligosaccharide presentation and composition over early lactation. In this work, IgG was isolated from milk pooled from three cows at four time points over the first 10 days of lactation postparturition. Purified IgG was labeled with a fluorescent dye and interrogated with a microarray consisting of 48 carbohydrate-binding proteins (lectins) from plant, fungal, and bacterial sources. Lectin microarray profiles suggested that only subtle changes in the glycosylation of IgG occurred during days 2 and 3 of lactation, but by day 10, the lectin profile diverged from the other three time points. Monosaccharide analysis carried out after hydrolysis confirmed that the ratios of oligosaccharide components remained relatively stable through day 3 and also that sialylation was substantially reduced by day 10. The differences that were observed for glycosylation suggest that different functionalities associated with IgG glycosylation may be required in the first days of life.

Glycomacropeptide Reduces Intestinal Epithelial Cell Barrier Dysfunction and Adhesion of Entero-Hemorrhagic and Entero-Pathogenic Escherichia coli in Vitro.

In recent years, the potential of glycosylated food components to positively influence health has received considerable attention. Milk is a rich source of biologically active glycoconjugates which are associated with antimicrobial, immunomodulatory, anti-adhesion, anti-inflammatory and prebiotic properties. Glycomacropeptide (GMP) is the C-terminal portion of kappa-casein that is released from whey during cheese-making by the action of chymosin. Many of the biological properties associated with GMP, such as anti-adhesion, have been linked with the carbohydrate portion of the protein. In this study, we investigated the ability of GMP to inhibit the adhesion of a variety of pathogenic Escherichia coli strains to HT-29 and Caco-2 intestinal cell lines, given the importance of E. coli in causing bacterial gastroenteritis. GMP significantly reduced pathogen adhesion, albeit with a high degree of species specificity toward enteropathogenic E. coli (EPEC) strains O125:H32 and O111:H2 and enterohemorrhagic E. coli (EHEC) strain 12900 O157:H7. The anti-adhesive effect resulted from the interaction of GMP with the E. coli cells and was also dependent on GMP concentration. Pre-incubation of intestinal Caco-2 cells with GMP reduced pathogen translocation as represented by a decrease in transepithelial electrical resistance (TEER). Thus, GMP is an effective in-vitro inhibitor of adhesion and epithelial injury caused by E. coli and may have potential as a biofunctional ingredient in foods to improve gastrointestinal health.