Project description:Human serum IgM antibodies are composed of heavily glycosylated polymers with five glycosylation sites on the μ (heavy) chain and one glycosylation site on the J chain. In contrast to IgG glycans, which are vital for a number of biological functions, virtually nothing is known about structure-function relationships of IgM glycans. Natural IgM is the earliest immunoglobulin produced and recognizes multiple antigens with low affinity, whilst immune IgM is induced by antigen exposure and is characterized by a higher antigen specificity. Natural anti-lymphocyte IgM is present in the serum of healthy individuals and increases in inflammatory conditions. It is able to inhibit T cell activation, but the underlying molecular mechanism is not understood. Here we show, for the first time, that sialylated N-linked glycans induce the internalization of IgM by T cells, which in turn causes severe inhibition of T cell responses. The absence of sialic acid residues abolishes these inhibitory activities, showing a key role of sialylated N-glycans in inducing the IgM-mediated immune suppression.
Project description:Bifidobacterium species in the infant gut can metabolize intact human milk oligosaccrides. There is species varation in the types of the olgosaccharides that can bedigested by Bifidobacterium species. B. breve strains have shown digestion of LNT and LNnT oligoscchrides. The objective of te current study was idetification of B. breve strains that can digest sialylated oligosacchrides. The currnet study was designed to idetify the genes that show upregulation when grown in lactose, 3'-siallylactose and Bovine Milk Oligosaccharides
Project description:Activation of murine CD4+ and CD8+ T lymphocytes leads to dramatic remodeling of N-linked glycans. Naïve and activated CD4 T cells, CD8 T cells and B cells were compared for their N-linked glycan structures by MALDI-TOF MS profiling and for expression of glycan transferase genes to assess the biosynthetic basis for any change observed. The major change observed in activated CD4 and CD8 T cells was dramatic reduction of sialylated bi-antennary N-glycans carrying the terminal NeuGc?2-6Gal sequence, and corresponding increase in glycans carrying the Gal?1-3Gal sequence. This change was accounted for by a decrease in the expression of the sialyltransferase ST6Gal, and increase in the expression of the galactosyltransferase ?1-3GalT. Conversely, in B cells no change in terminal sialylation of N-linked glycans was evident, and the expression of the same two glycosyltransferases were increased and decreased, respectively. Keywords = N-linked glycosylation, T cell, B cell, activation, glycosyltransferase, carbohydrate, glycomics, glycan, galactosyltransferase, sialyltransferase Keywords: other
Project description:A comprehensive glycosylation profile of donkey lactoferrin, isolated by ion exchange chromatography from an individual milk sample, was obtained by means of chymotryptic digestion, TiO2 and HILIC enrichment, reversed-phase high performance liquid chromatography, electrospray mass spectrometry, and high collision dissociation fragmentation. The results obtained allowed the identification of 26 different glycan structures, including high mannose, complex and hybrid N-glycans, linked to the protein backbone via an amide bond to asparagine residues located at the positions 137, 281 and 476. Altogether, the N-glycan structures determined revealed that in donkey milk lactoferrin most of the N-glycans identified are neutral complex/hybrid. Actually, 10 neutral non-fucosylated complex/hybrid N-glycans and 4 neutral fucosylated complex/hybrid N-glycans were found. In addition, 2 high mannose N-glycans, 4 sialylated fucosylated complex/hybrid N-glycans and 6 sialylated non-fucosylatedN-glycans, one of which containing N-glycolylneuramin acid (Neu5Gc), were found. A comparison of the glycosylation profile of donkey milk lactoferrin with respect to that of human, bovine and goat milk lactoferrin is reported.
Project description:The majority of babies in the US are formula-fed instead of breast fed. There are major differences in the composition of formulas and breast milk and yet little is known about metabolic differences in babies as the result of feeding these very different diets and how that might affect development or disease risk in later life. One concern is that soy-based formulas might have adverse health effects in babies as a result of the presence of low levels of estrogenic phytochemicals genistein and daidzein which are normally present in soy beans. In the current study, we used a piglet model to look at this question. Piglets were either fed breast milk from the sow or were fed two different infant formulas (cow's milk-based or soy-based) from age 2 days to 21 days when pigs are normally weaned onto solid food. Blood glucose and lipids were measured. Formula-fed pigs were found to have lower cholesterol than breast fed piglets and in addition had larger stores of iron in their liver.Microarray analysis was carried out to see if changes in liver gene expression could explain these effects of formula feeding. It was found that overall gene expression profiles were influenced by formula feeding compared to breast fed neonates. Gender-independent and unique effects of formula influenced cholesterol and iron metabolism. Further, soy formula feeding in comparison to milk-based formula failed to reveal any estrogenic actions on hepatic gene expression in either male or female pigs. Piglets (female, male) were either fed breast milk from the sow or were fed two different infant formulas (cow's milk-based or soy-based) from age 2 days to 21 days when pigs are normally weaned onto solid food.
Project description:Symbiotic bacteria inhabiting the distal human gut have evolved under intense pressure to utilize complex carbohydrates, predominantly plant cell wall glycans abundant in our diets. These substrates are recalcitrant to depolymerization by digestive enzymes encoded in the human genome, but are efficiently targeted by some of the ~103-104 bacterial species that inhabit this niche. These species augment our comparatively narrow carbohydrate digestive capacity by unlocking otherwise unusable sugars and fermenting them into host-absorbable forms, such as short-chain fatty acids. We used phenotype profiling, whole-genome transcriptional analysis and molecular genetic approaches to investigate complex glycan utilization by two fully sequenced and closely related human gut symbionts: Bacteroides thetaiotaomicron and Bacteroides ovatus. Together these species target all of the common glycosidic linkages found in the plant cell wall, as well as host polysaccharides, but each species exhibits a unique ‘glycan niche’: in vitro B. thetaiotaomicron targets plant cell wall pectins in addition to linkages contained in host N- and O-glycans; B. ovatus uniquely targets hemicellulosic polysaccharides along with several pectins, but is deficient in host glycan utilization. Bacteroides ovatus bacteria were grown either in vitro on defined complex glycan sources, or in vivo in the intestinal tract of gnotobiotic mice fed variable diets. Increased in vitro gene expression was used to indicate the genes required for metabolism of complex glycans and compared to in vivo transcriptional activity to determine expression in the mouse gut.
Project description:We want to characterize the glycan moieties on the surface of leukocytes treated with fluorinated analogs of glucosamine. Since these metabolic inhibitors compete with natural-occuring glucosamine used in oligosaccharide chain formation, these compounds have been shown to be effective in lowering Type 2 lactosamine and sialylated Lewis antigens, which results in altered selectin ligand functions. We need to establish specific structural evidence that glycans are indeed blunted/altered. Current research efforts include investigations on how circulating leukocytes traffic to inflamed tissues, how circulating solid tumor cells interact with endothelial linings to enhance metastatic potential, and how treatment with analogs of glucosamine disrupt leukocyte trafficking mechanisms and/or influence effector/regulatory function of T cells.
Project description:We compare the transcriptome of gnotobiotic Ae. aegypti generated by contaminating axenic (bacteria-free) larvae with bacterial isolates found in natural mosquito breeding sites. We focused on four bacterial isolates (Lysobacter, Flavobacterium, Paenibacillus and Enterobacteriaceae) and found that different gnotobiotic treatments resulted in massive transcriptomic changes throughout the mosquito development.