Structural basis for the interaction between human milk oligosaccharides and the bacterial lectin PA-IIL of Pseudomonas aeruginosa

One of the mechanisms contributing to the protection by breast-feeding of the newborn against enteric diseases is related to the ability of human milk oligosaccharides to prevent the attachment of pathogenic bacteria to the duodenual epithelium. Indeed, a variety of fucosylated oligosaccharides, specific to human milk, form part of the innate immune system. In the present study, we demonstrate the specific blocking of PA-IIL, a fucose-binding lectin of the human pathogen Pseudomonas aeruginosa, by milk oligosaccharides. Two fucosylated epitopes, Lewis a and 3-fucosyl-lactose (Lewis x glucose analogue) bind to the lectin with dissociation constants of 2.2×10−7 M and 3.6×10−7 M respectively. Thermodynamic studies indicate that these interactions are dominated by enthalpy. The entropy contribution is slightly favourable when binding to fucose and to the highest-affinity ligand, Lewis a. The high-resolution X-ray structures of two complexes of PA-IIL with milk oligosaccharides allow the precise determination of the conformation of a trisaccharide and a pentasaccharide. The different types of interaction between the oligosaccharides and the protein involve not only hydrogen bonding, but also calcium- and water-bridged contacts, allowing a rationalization of the thermodynamic data. This study provides important structural information about compounds that could be of general application in new therapeutic strategies against bacterial infections.

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Structural Basis for Norovirus Inhibition by Human Milk Oligosaccharides

Journal of Virology ◽

10.1128/jvi.03223-15 ◽

2016 ◽

Vol 90 (9) ◽

pp. 4843-4848 ◽

Cited By ~ 61

Author(s):

Stefan Weichert ◽

Anna Koromyslova ◽

Bishal K. Singh ◽

Satoko Hansman ◽

Stefan Jennewein ◽

...

Keyword(s):

Human Milk ◽

Blood Group ◽

Structural Basis ◽

Blood Group Antigens ◽

Human Milk Oligosaccharides ◽

Milk Oligosaccharides ◽

X Ray ◽

X Ray Crystallography ◽

Naturally Occurring

Histo-blood group antigens (HBGAs) are important binding factors for norovirus infections. We show that two human milk oligosaccharides, 2′-fucosyllactose (2′FL) and 3-fucosyllactose (3FL), could block norovirus from binding to surrogate HBGA samples. We found that 2′FL and 3FL bound at the equivalent HBGA pockets on the norovirus capsid using X-ray crystallography. Our data revealed that 2′FL and 3FL structurally mimic HBGAs. These results suggest that 2′FL and 3FL might act as naturally occurring decoys in humans.

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Assessment of the synbiotic properites of human milk oligosaccharides and Bifidobacterium longum subsp. infantis in vitro and in humanised mice

Beneficial Microbes ◽

10.3920/bm2016.0138 ◽

2017 ◽

Vol 8 (2) ◽

pp. 281-289 ◽

Cited By ~ 4

Author(s):

S. Musilova ◽

N. Modrackova ◽

P. Hermanova ◽

T. Hudcovic ◽

R. Svejstil ◽

...

Keyword(s):

Caesarean Section ◽

Human Milk ◽

Pathogenic Bacteria ◽

Bifidobacterium Longum ◽

Mode Of Delivery ◽

Human Milk Oligosaccharides ◽

Milk Oligosaccharides ◽

High Concentrations

The mode of delivery plays a crucial role in infant gastrointestinal tract colonisation, which in the case of caesarean section is characterised by the presence of clostridia and low bifidobacterial counts. Gut colonisation can be modified by probiotics, prebiotics or synbiotics. Human milk oligosaccharides (HMOs) are infant prebiotics that show a bifidogenic effect. Moreover, genome sequencing of Bifidobacterium longum subsp. infantis within the infant microbiome revealed adaptations for milk utilisation. This study aimed to evaluate the synbiotic effect of B. longum subsp. infantis, HMOs and human milk (HM) both in vitro and in vivo (in a humanised mouse model) in the presence of faecal microbiota from infants born by caesarean section. The combination of B. longum and HMOs or HM reduced the clostridia and G-bacteria counts both in vitro and in vivo. The bifidobacterial population in vitro significantly increased and produce high concentrations of acetate and lactate. In vitro competition assays confirmed that the tested bifidobacterial strain is a potential probiotic for infants and, together with HMOs or HM, acts as a synbiotic. It is also able to inhibit potentially pathogenic bacteria. The synbiotic effects identified in vitro were not observed in vivo. However, there was a significant reduction in clostridia counts in both experimental animal groups (HMOs + B. longum and HM + B. longum), and a specific immune response via increased interleukin (IL)-10 and IL-6 production. Animal models do not perfectly mimic human conditions; however, they are essential for testing the safety of functional foods.

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Selective Utilization of the Human Milk Oligosaccharides 2′-Fucosyllactose, 3-Fucosyllactose, and Difucosyllactose by Various Probiotic and Pathogenic Bacteria

Journal of Agricultural and Food Chemistry ◽

10.1021/acs.jafc.0c06041 ◽

2020 ◽

Author(s):

Krista Salli ◽

Johanna Hirvonen ◽

Jani Siitonen ◽

Ilmari Ahonen ◽

Heli Anglenius ◽

...

Keyword(s):

Human Milk ◽

Pathogenic Bacteria ◽

Human Milk Oligosaccharides ◽

Milk Oligosaccharides

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Human Milk Oligosaccharides Exhibit Biofilm Eradication Activity Against Matured Biofilms Formed by Different Pathogen Species

Frontiers in Microbiology ◽

10.3389/fmicb.2021.794441 ◽

2022 ◽

Vol 12 ◽

Author(s):

Sylwia Jarzynka ◽

Riccardo Spott ◽

Tinatini Tchatchiashvili ◽

Nico Ueberschaar ◽

Mark Grevsen Martinet ◽

...

Keyword(s):

Human Milk ◽

Pathogenic Bacteria ◽

Biological Significance ◽

Burkholderia Cenocepacia ◽

Respiratory Pathogens ◽

Human Milk Oligosaccharides ◽

Group B Streptococci ◽

Milk Oligosaccharides ◽

Gram Positive ◽

Group B

Human milk oligosaccharides (HMOs) have been shown to exhibit plenty of benefits for infants, such as prebiotic activity shaping the gut microbiota and immunomodulatory and anti-inflammatory activity. For some pathogenic bacteria, antimicrobial activity has been proved, but most studies focus on group B streptococci. In the present study, we investigated the antimicrobial and antibiofilm activities of the total and fractionated HMOs from pooled human milk against four common human pathogenic Gram-negative species (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Burkholderia cenocepacia) and three Gram-positive species (Staphylococcus aureus, Enterococcus faecium, and Enterococcus faecalis). The activity of HMOs against enterococci and B. cenocepacia are addressed here for the first time. We showed that HMOs exhibit a predominant activity against the Gram-positive species, with E. faecalis being the most sensitive to the HMOs, both in planktonic bacteria and in biofilms. In further tests, we could exclude fucosyllactose as the antibacterial component. The biological significance of these findings may lie in the prevention of skin infections of the mother’s breast as a consequence of breastfeeding-induced skin laceration and/or protection of the infants’ nasopharynx and lung from respiratory pathogens such as staphylococci.

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Beneficial effects of human milk oligosaccharides on gut microbiota

Beneficial Microbes ◽

10.3920/bm2013.0080 ◽

2014 ◽

Vol 5 (3) ◽

pp. 273-283 ◽

Cited By ~ 61

Author(s):

S. Musilova ◽

V. Rada ◽

E. Vlkova ◽

V. Bunesova

Keyword(s):

Gut Microbiota ◽

Human Milk ◽

Pathogenic Bacteria ◽

Structural Diversity ◽

Human Milk Oligosaccharides ◽

High Concentration ◽

Milk Oligosaccharides ◽

Beneficial Effects ◽

Specific Effects ◽

The Relationship

Human milk is the gold standard for nourishment of early infants because it contains a number of bioactive components, such as human milk oligosaccharides (HMOs). The high concentration and structural diversity of HMOs are unique to humans. HMOs are a group of complex and diverse glycans that are resistant to gastrointestinal digestion and reach the infant colon as the first prebiotics. N-acetyl-glucosamine containing oligosaccharides were first identified 50 years ago as the ‘bifidus factor’, a selective growth substrate for intestinal bifidobacteria, thus providing a conceptual basis for HMO-specific bifidogenic activity. Bifidobacterial species are the main utilisers of HMOs in the gastrointestinal tract and represent the dominant microbiota of breast-fed infants, and they may play an important role in maintaining the general health of newborn children. Oligosaccharides are also known to directly interact with the surface of pathogenic bacteria, and various oligosaccharides in milk are believed to inhibit the binding of pathogens and toxins to host cell receptors. Furthermore, HMOs are thought to contribute to the development of infant intestine and brain. Oligosaccharides currently added to infant formula are structurally different from the oligosaccharides naturally occurring in human milk and, therefore, they are unlikely to mimic some of the structure-specific effects. In this review, we describe how HMOs can modulate gut microbiota. This article summarises information up to date about the relationship between the intestinal microbiota and HMOs, and other possible indirect effects of HMOs on intestinal environment.

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