Background: Many enteric pathogens bind fucosylated glycans of host cell receptors, which include... more Background: Many enteric pathogens bind fucosylated glycans of host cell receptors, which includes the H-2 epitope. These glycans, synthesized by fucosyltransferases encoded by the ABO/Lewis histo-blood group genes, may determine innate risk of diarrhea. Methods: A cohort of 297 Mexican children was followed from birth to 2 years of age with weekly surveillance for diarrhea; cases were diagnosed and characterized by a study physician. Saliva and blood samples were analyzed to define histo-blood group genotypes and phenotypes, and their relationship to risk of diarrhea. Results: Children with O Lewis a-b- blood group type, who express Fucα1,2 (H-2) epitopes, had the highest risk of diarrhea, 3.0 episodes/child-yr. Non-secretor children (O Lewis a+b- blood group, who do not express H-2 epitopes) had the lowest risk, 1.5 diarrhea episodes/child-yr (P=0.002). Those of A and B blood groups, who express H-2, but with an additional sugar at the terminus that partially masks binding, had in...
Late onset sepsis (LOS) contributes to mortality and morbidity in preterm infants. We tested the ... more Late onset sepsis (LOS) contributes to mortality and morbidity in preterm infants. We tested the hypotheses that microbes causing LOS originate from the gut, and that distortions in the gut microbial community increases subsequent risk of LOS. We examined the gut microbial community in prospectively collected stool samples from preterm infants with LOS and an equal number of age-matched controls at two sites (Cincinnati, OH and Birmingham, AL), by sequencing the bacterial 16S rDNA. We confirmed our findings in a subset of infants by whole genome shotgun sequencing, and analyzed the data using R and LEfSe. Infants with LOS in Cincinnati, as compared to controls, had less abundant Actinobacteria in the first samples after birth (median 18 days before sepsis onset), and less abundant Pseudomonadales in the last samples collected prior to LOS (median 8 days before sepsis onset). Infants with LOS in Birmingham, as compared to controls, had no differences identified in the first sample mi...
Journal of human lactation : official journal of International Lactation Consultant Association, Jan 13, 2015
Most protective components in human milk are stable during prolonged storage at 4ºC; however, pas... more Most protective components in human milk are stable during prolonged storage at 4ºC; however, pasteurization reduces some microbicidal activities responsible for suppressing microbial growth and protecting against infection. Donor milk used by neonatal intensive care units (NICUs) is frozen pasteurized donor human milk (PDHM) defrosted and stored at 4ºC. Current Human Milk Banking Association of North America (HMBANA) Best Practice guidelines recommend that milk be discarded 24 hours after being thawed, but experimental data on the duration of microbiological purity in thawed PDHM are sparse. This study evaluates microbiological purity of thawed PDHM during prolonged storage at 4ºC. A total of 42 independent, randomly selected PDHM samples were thawed at 4ºC. As is typical in NICUs, each bottle was opened at 3-hour intervals and 3 mL was withdrawn with a sterile syringe and transferred into a sterile tube. The 3 mL samples removed at 0, 24, 48, 72, 96 hours, and 9 days were tested f...
Breast-feeding is a highly effective strategy for preventing morbidity and mortality in infancy. ... more Breast-feeding is a highly effective strategy for preventing morbidity and mortality in infancy. The human-milk glycans, which include oligosaccharides in their free and conjugated forms, constitute a major and an innate immunologic mechanism by which human milk protects breast-fed infants against infections. The glycans found in human milk function as soluble receptors that inhibit pathogens from adhering to their target receptors on the mucosal surface of the host gastrointestinal tract. The alpha1,2-linked fucosylated glycans, which require the secretor gene for expression in human milk, are the dominant glycan structure found in the milk of secretor mothers, who constitute the majority ( approximately 80%) of mothers worldwide. In vitro and in vivo binding studies have demonstrated that alpha1,2-linked fucosylated glycans inhibit binding by campylobacter, stable toxin of enterotoxigenic Escherichia coli, and major strains of caliciviruses to their target host cell receptors. Con...
Several pathogenic agents of pediatric gastroenteritis are inhibited by fucosylated oligosacchari... more Several pathogenic agents of pediatric gastroenteritis are inhibited by fucosylated oligosaccharides of human milk. Biosynthesis and degradation of fucosyloligosaccharides is controlled by fucosyltransferase and alpha-L-fucosidase. The activity of these enzymes varies reciprocally over the course of lactation. We hypothesized that differences in the specific organization of these enzymes in compartments of human milk might contribute to such differences in activity. Therefore, the distribution of these enzymes in various compartments of human milk was investigated. After ultracentrifugation at 120,000g for 2h, the fucosyltransferase activity distributes evenly between the supernatant and the membranous pellet. Ultracentrifugation at 180,000g for 17 h further fractionated the milk into a clear supernatant, a fluff layer from the supernatant, and a pellet. The fluff was visualized by electron microscopy. The distribution of fucosyltransferase activity in colostrum was compared with th...
Infants begin acquiring intestinal microbiota at parturition. Initial colonization by pioneer bac... more Infants begin acquiring intestinal microbiota at parturition. Initial colonization by pioneer bacteria is followed by active succession toward a dynamic ecosystem. Keystone microbes engage in reciprocal transkingdom communication with the host, which is essential for human homeostasis and health; therefore, these bacteria should be considered mutualists rather than commensals. This review discusses the maternal role in providing infants with functional and stable microbiota. The initial fecal inoculum of microbiota results from the proximity of the birth canal and anus; the biological significance of this anatomic proximity could underlie observed differences in microbiota between vaginal and cesarean birth. Secondary sources of inocula include mouths and skin of kin, animals and objects, and the human milk microbiome, but guiding microbial succession may be a primary role of human milk. The unique glycans of human milk cannot be digested by the infant, but are utilized by mutualist bacteria. These prebiotic glycans support expansion of mutualist microbiota, which manifests as differences in microbiota among breastfed and artificially fed infants. Human milk glycans vary by maternal genotype. Milks of genetically distinct mothers and variations in infant mucosal glycan expression support discrete microbiota. Early colonization may permanently influence microbiota composition and function, with ramifications for health.
A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammati... more A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammation through lipopolysaccharide (LPS) binding to intestinal toll-like receptor 4 (TLR4). Breast feeding lowers risk of disease, and human milk modulates inflammation. This study tested whether human milk oligosaccharides (HMOSs) influence pathogenic Escherichia coli-induced interleukin (IL)-8 release by intestinal epithelial cells (IECs), identified specific proinflammatory signalling molecules modulated by HMOSs, specified the active HMOS and determined its mechanism of action. Models of inflammation were IECs invaded by type 1 pili enterotoxigenic E. coli (ETEC) in vitro: T84 modelled mature, and H4 modelled immature IECs. LPS-induced signalling molecules co-varying with IL-8 release in the presence or absence of HMOSs were identified. Knockdown and overexpression verified signalling mediators. The oligosaccharide responsible for altered signalling was identified. HMOSs attenuated LPS-de...
Background: Many enteric pathogens bind fucosylated glycans of host cell receptors, which include... more Background: Many enteric pathogens bind fucosylated glycans of host cell receptors, which includes the H-2 epitope. These glycans, synthesized by fucosyltransferases encoded by the ABO/Lewis histo-blood group genes, may determine innate risk of diarrhea. Methods: A cohort of 297 Mexican children was followed from birth to 2 years of age with weekly surveillance for diarrhea; cases were diagnosed and characterized by a study physician. Saliva and blood samples were analyzed to define histo-blood group genotypes and phenotypes, and their relationship to risk of diarrhea. Results: Children with O Lewis a-b- blood group type, who express Fucα1,2 (H-2) epitopes, had the highest risk of diarrhea, 3.0 episodes/child-yr. Non-secretor children (O Lewis a+b- blood group, who do not express H-2 epitopes) had the lowest risk, 1.5 diarrhea episodes/child-yr (P=0.002). Those of A and B blood groups, who express H-2, but with an additional sugar at the terminus that partially masks binding, had in...
Late onset sepsis (LOS) contributes to mortality and morbidity in preterm infants. We tested the ... more Late onset sepsis (LOS) contributes to mortality and morbidity in preterm infants. We tested the hypotheses that microbes causing LOS originate from the gut, and that distortions in the gut microbial community increases subsequent risk of LOS. We examined the gut microbial community in prospectively collected stool samples from preterm infants with LOS and an equal number of age-matched controls at two sites (Cincinnati, OH and Birmingham, AL), by sequencing the bacterial 16S rDNA. We confirmed our findings in a subset of infants by whole genome shotgun sequencing, and analyzed the data using R and LEfSe. Infants with LOS in Cincinnati, as compared to controls, had less abundant Actinobacteria in the first samples after birth (median 18 days before sepsis onset), and less abundant Pseudomonadales in the last samples collected prior to LOS (median 8 days before sepsis onset). Infants with LOS in Birmingham, as compared to controls, had no differences identified in the first sample mi...
Journal of human lactation : official journal of International Lactation Consultant Association, Jan 13, 2015
Most protective components in human milk are stable during prolonged storage at 4ºC; however, pas... more Most protective components in human milk are stable during prolonged storage at 4ºC; however, pasteurization reduces some microbicidal activities responsible for suppressing microbial growth and protecting against infection. Donor milk used by neonatal intensive care units (NICUs) is frozen pasteurized donor human milk (PDHM) defrosted and stored at 4ºC. Current Human Milk Banking Association of North America (HMBANA) Best Practice guidelines recommend that milk be discarded 24 hours after being thawed, but experimental data on the duration of microbiological purity in thawed PDHM are sparse. This study evaluates microbiological purity of thawed PDHM during prolonged storage at 4ºC. A total of 42 independent, randomly selected PDHM samples were thawed at 4ºC. As is typical in NICUs, each bottle was opened at 3-hour intervals and 3 mL was withdrawn with a sterile syringe and transferred into a sterile tube. The 3 mL samples removed at 0, 24, 48, 72, 96 hours, and 9 days were tested f...
Breast-feeding is a highly effective strategy for preventing morbidity and mortality in infancy. ... more Breast-feeding is a highly effective strategy for preventing morbidity and mortality in infancy. The human-milk glycans, which include oligosaccharides in their free and conjugated forms, constitute a major and an innate immunologic mechanism by which human milk protects breast-fed infants against infections. The glycans found in human milk function as soluble receptors that inhibit pathogens from adhering to their target receptors on the mucosal surface of the host gastrointestinal tract. The alpha1,2-linked fucosylated glycans, which require the secretor gene for expression in human milk, are the dominant glycan structure found in the milk of secretor mothers, who constitute the majority ( approximately 80%) of mothers worldwide. In vitro and in vivo binding studies have demonstrated that alpha1,2-linked fucosylated glycans inhibit binding by campylobacter, stable toxin of enterotoxigenic Escherichia coli, and major strains of caliciviruses to their target host cell receptors. Con...
Several pathogenic agents of pediatric gastroenteritis are inhibited by fucosylated oligosacchari... more Several pathogenic agents of pediatric gastroenteritis are inhibited by fucosylated oligosaccharides of human milk. Biosynthesis and degradation of fucosyloligosaccharides is controlled by fucosyltransferase and alpha-L-fucosidase. The activity of these enzymes varies reciprocally over the course of lactation. We hypothesized that differences in the specific organization of these enzymes in compartments of human milk might contribute to such differences in activity. Therefore, the distribution of these enzymes in various compartments of human milk was investigated. After ultracentrifugation at 120,000g for 2h, the fucosyltransferase activity distributes evenly between the supernatant and the membranous pellet. Ultracentrifugation at 180,000g for 17 h further fractionated the milk into a clear supernatant, a fluff layer from the supernatant, and a pellet. The fluff was visualized by electron microscopy. The distribution of fucosyltransferase activity in colostrum was compared with th...
Infants begin acquiring intestinal microbiota at parturition. Initial colonization by pioneer bac... more Infants begin acquiring intestinal microbiota at parturition. Initial colonization by pioneer bacteria is followed by active succession toward a dynamic ecosystem. Keystone microbes engage in reciprocal transkingdom communication with the host, which is essential for human homeostasis and health; therefore, these bacteria should be considered mutualists rather than commensals. This review discusses the maternal role in providing infants with functional and stable microbiota. The initial fecal inoculum of microbiota results from the proximity of the birth canal and anus; the biological significance of this anatomic proximity could underlie observed differences in microbiota between vaginal and cesarean birth. Secondary sources of inocula include mouths and skin of kin, animals and objects, and the human milk microbiome, but guiding microbial succession may be a primary role of human milk. The unique glycans of human milk cannot be digested by the infant, but are utilized by mutualist bacteria. These prebiotic glycans support expansion of mutualist microbiota, which manifests as differences in microbiota among breastfed and artificially fed infants. Human milk glycans vary by maternal genotype. Milks of genetically distinct mothers and variations in infant mucosal glycan expression support discrete microbiota. Early colonization may permanently influence microbiota composition and function, with ramifications for health.
A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammati... more A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammation through lipopolysaccharide (LPS) binding to intestinal toll-like receptor 4 (TLR4). Breast feeding lowers risk of disease, and human milk modulates inflammation. This study tested whether human milk oligosaccharides (HMOSs) influence pathogenic Escherichia coli-induced interleukin (IL)-8 release by intestinal epithelial cells (IECs), identified specific proinflammatory signalling molecules modulated by HMOSs, specified the active HMOS and determined its mechanism of action. Models of inflammation were IECs invaded by type 1 pili enterotoxigenic E. coli (ETEC) in vitro: T84 modelled mature, and H4 modelled immature IECs. LPS-induced signalling molecules co-varying with IL-8 release in the presence or absence of HMOSs were identified. Knockdown and overexpression verified signalling mediators. The oligosaccharide responsible for altered signalling was identified. HMOSs attenuated LPS-de...
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Papers by David Newburg