Project description:Here we studied the glycation of bovine milk proteins by lactose as dominant sugar in milk and hexoses using tandem mass spectrometry (CID and ETD mode). In a bottom-up proteomics approach after enriching glycated peptides by boronate affinity chromatography, first we could identify 260 lactosylated peptides corresponding to 124 lactosylation sites in 28 bovine milk proteins in raw milk, raw colostrum, three brands of pasteurized milk, three brands of UHT milk, and five brands of infant formula. The same regular and additionally two lactose-free milk products (pasteurized and UHT milk) where lactose is enzymatically cleaved into the more reactive hexoses were analyzed in terms of hexosylation sites that resulted in identification of 124 hexosylated tryptic peptides corresponding to 86 glycation sites in 17 bovine milk proteins. In quantitative terms glycation increased from raw milk to pasteurized milk to UHT milk and infant formula, i.e., with the harsher processing conditions. Lactose-free milk contained significantly higher hexosylation degrees than the corresponding regular milk product.
Project description:Intake of high-fat foods raises postprandial plasma triglycerides and inflammatory markers, which may depend on the type of fat ingested. Dairy products are commonly consumed, but not much is known about the impact of milk fat and the milk fat globule membrane on postprandial inflammation. Here, we aimed to study the effect of milk fat with and without milk fat globule membrane and vegetable blend fat on post-prandial inflammation, with a focus on blood monocyte gene expression. We performed a randomized, double-blind cross-over trial in middle-aged healthy male and female volunteers (BMI 22–27 kg/m2). The participants consumed a meal shake containing 95.5 g of fat consisting of either a vegetable fat blend (VEGE), anhydrous milk fat (AMF, without milk fat globule membrane), or cream (CREAM, containing milk fat globule membrane). Blood monocytes were collected at 0 and 6 hours postprandially and used for bulk RNA sequencing and ex vivo stimulation with LPS. Consumption of all three shakes significantly decreased the percentage of classical monocytes and increased the percentages of intermediate monocytes and non-classical monocytes. No differences in these measures were observed between shakes. Using a threshold of p < 0.01, 787 genes were differentially regulated postprandially between the three shakes. 89 genes were differentially regulated postprandially between AMF and VEGE, 373 genes between AMF and CREAM, and 667 genes between VEGE and CREAM, indicating that the effect of CREAM on monocyte gene expression was distinct from AMF and VEGE. Pathway analyses showed that VEGE significantly increased the expression of genes involved in inflammatory pathways, whereas this was less pronounced after AMF and not observed after CREAM. In addition, CREAM significantly down-regulated the expression of genes involved in energy metabolism-related pathways, such as glycolysis, TCA cycle, and oxidative phosphorylation, as well as HIF1 signaling. Compared to the consumption of an anhydrous milk fat without milk fat globule membrane and a vegetable fat blend, the consumption of cream with milk fat globule membrane downregulated inflammatory pathways in blood monocytes, thus suggesting a potential inflammation inhibitory effect of milk fat globule membrane.
Project description:Previous work has demonstrated that elevated maternal lipid intake (particularly from dairy products) is associated with increased lipids and altered fatty acid profile in milk produced by healthy lactating women. We investigate our primary hypothesis that a maternal diet rich in full-fat dairy products would simultaneously increase milk lipid percent and expression of genes related to the uptake and/or de novo biosynthesis of milk lipids.