Treatment of Helicobacter pylori infection in rhesus monkeys using a novel antiadhesion compound

The role of glycans in health and disease: Regulators of the interaction between gut microbiota and host immune system

The human gut microbiota is home to a diverse collection of microorganisms that has co-evolved with the host immune system in which host-microbiota interactions are essential to preserve health and homeostasis. Evidence suggests that the perturbation of this symbiotic host-microbiome relationship contributes to the onset of major diseases such as chronic inflammatory diseases including Inflammatory Bowel Disease. The host glycocalyx (repertoire of glycans/sugar-chains at the surface of gut mucosa) constitutes a major biological and physical interface between the intestinal mucosa and microorganisms, as well as with the host immune system. Glycans are an essential niche for microbiota colonization and thus an important modulator of host-microorganism interactions both in homeostasis and in disease. In this review, we discuss the role of gut mucosa glycome as an instrumental pathway that regulates host-microbiome interactions in homeostasis but also in health to inflammation transition. We also discuss the power of mucosa glycosylation remodelling as an attractive preventive and therapeutic strategy to preserve gut homeostasis.

Membrane lipid remodeling eradicates Helicobacter pylori by manipulating the cholesteryl 6'-acylglucoside biosynthesis

BACKGROUND

Helicobacter pylori, the main cause of various gastric diseases, infects approximately half of the human population. This pathogen is auxotrophic for cholesterol which it converts to various cholesteryl α-glucoside derivatives, including cholesteryl 6'-acyl α-glucoside (CAG). Since the related biosynthetic enzymes can be translocated to the host cells, the acyl chain of CAG likely comes from its precursor phosphatidylethanolamine (PE) in the host membranes. This work aims at examining how the acyl chain of CAG and PE inhibits the membrane functions, especially bacterial adhesion.

METHODS

Eleven CAGs that differ in acyl chains were used to study the membrane properties of human gastric adenocarcinoma cells (AGS cells), including lipid rafts clustering (monitored by immunofluorescence with confocal microscopy) and lateral membrane fluidity (by the fluorescence recovery after photobleaching). Cell-based and mouse models were employed to study the degree of bacterial adhesion, the analyses of which were conducted by using flow cytometry and immunofluorescence staining, respectively. The lipidomes of H. pylori, AGS cells and H. pylori-AGS co-cultures were analyzed by Ultraperformance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS) to examine the effect of PE(10:0)2, PE(18:0)2, PE(18:3)2, or PE(22:6)2 treatments.

RESULTS

CAG10:0, CAG18:3 and CAG22:6 were found to cause the most adverse effect on the bacterial adhesion. Further LC-MS analysis indicated that the treatment of PE(10:0)2 resulted in dual effects to inhibit the bacterial adhesion, including the generation of CAG10:0 and significant changes in the membrane compositions. The initial (1 h) lipidome changes involved in the incorporation of 10:0 acyl chains into dihydro- and phytosphingosine derivatives and ceramides. In contrast, after 16 h, glycerophospholipids displayed obvious increase in their very long chain fatty acids, monounsaturated and polyunsaturated fatty acids that are considered to enhance membrane fluidity.

CONCLUSIONS

The PE(10:0)2 treatment significantly reduced bacterial adhesion in both AGS cells and mouse models. Our approach of membrane remodeling has thus shown great promise as a new anti-H. pylori therapy.

LOX-1 acts as an N6-methyladenosine-regulated receptor for Helicobacter pylori by binding to the bacterial catalase

The role of N6-methyladenosine (m6A) modification of host mRNA during bacterial infection is unclear. Here, we show that Helicobacter pylori infection upregulates host m6A methylases and increases m6A levels in gastric epithelial cells. Reducing m6A methylase activity via hemizygotic deletion of methylase-encoding gene Mettl3 in mice, or via small interfering RNAs targeting m6A methylases, enhances H. pylori colonization. We identify LOX-1 mRNA as a key m6A-regulated target during H. pylori infection. m6A modification destabilizes LOX-1 mRNA and reduces LOX-1 protein levels. LOX-1 acts as a membrane receptor for H. pylori catalase and contributes to bacterial adhesion. Pharmacological inhibition of LOX-1, or genetic ablation of Lox-1, reduces H. pylori colonization. Moreover, deletion of the bacterial catalase gene decreases adhesion of H. pylori to human gastric sections. Our results indicate that m6A modification of host LOX-1 mRNA contributes to protection against H. pylori infection by downregulating LOX-1 and thus reducing H. pylori adhesion.

Dietary sialic acids: distribution, structure, and functions

Sialic acids (Sias), a group of over 50 structurally distinct acidic saccharides on the surface of all vertebrate cells, are neuraminic acid derivatives. They serve as glycan chain terminators in extracellular glycolipids and glycoproteins. In particular, Sias have significant implications in cell-to-cell as well as host-to-pathogen interactions and participate in various biological processes, including neurodevelopment, neurodegeneration, fertilization, and tumor migration. However, Sia is also present in some of our daily diets, particularly in conjugated form (sialoglycans), such as those in edible bird's nest, red meats, breast milk, bovine milk, and eggs. Among them, breast milk, especially colostrum, contains a high concentration of sialylated oligosaccharides. Numerous reviews have concentrated on the physiological function of Sia as a cellular component of the body and its relationship with the occurrence of diseases. However, the consumption of Sias through dietary sources exerts significant influence on human health, possibly by modulating the gut microbiota's composition and metabolism. In this review, we summarize the distribution, structure, and biological function of particular Sia-rich diets, including human milk, bovine milk, red meat, and egg.

Multifunctional Benefits of Prevalent HMOs: Implications for Infant Health

Breastfeeding is the best source of nutrition during infancy and is associated with a broad range of health benefits. However, there remains a significant and persistent need for innovations in infant formula that will allow infants to access a wider spectrum of benefits available to breastfed infants. The addition of human milk oligosaccharides (HMOs) to infant formulas represents the most significant innovation in infant nutrition in recent years. Although not a direct source of calories in milk, HMOs serve as potent prebiotics, versatile anti-infective agents, and key support for neurocognitive development. Continuing improvements in food science will facilitate production of a wide range of HMO structures in the years to come. In this review, we evaluate the relationship between HMO structure and functional benefits. We propose that infant formula fortification strategies should aim to recapitulate a broad range of benefits to support digestive health, immunity, and cognitive development associated with HMOs in breastmilk. We conclude that acetylated, fucosylated, and sialylated HMOs likely confer important health benefits through multiple complementary mechanisms of action.

The Potential for Sialic Acid and Sialylated Glycoconjugates as Feed Additives to Enhance Pig Health and Production

Simple Summary

This review discusses the current challenges in the pig industry and the potential nutritional significance of sialic acid (Sia) and glycoconjugates (Sia-GC’s) for pig health and nutrition. Sia is a nine-carbon acidic sugar which is present in various organs and body fluids of humans and animals. Sias contribute to many beneficial biological functions including pathogen resistance, immunomodulation, gut microbiota development, gut maturation, anti-inflammation and neurodevelopment. The role of Sias in regulating the metabolism of pigs has seldom been reported. However, we have documented significant beneficial effects of specific Sia-GC’s on health and production performance of sows and piglets. These findings are reviewed in relation to other studies while noting the beneficial effects of the inclusion of Sia, Sia containing oligosaccharide or the sialo-protein lactoferrin in the diets of gilts and sows. The importance of the passive transfer of of Sia and Sia-GC’s through milk to the young and the implications for their growth and development is also reviewed. This information will assist in optimizing the composition of sow/gilt milk replacers designed to increases the survival of IUGR piglets or piglets with dams suffering from agalactia, a common problem in pig production systems worldwide.

Abstract

Swine are one of the most important agricultural species for human food production. Given the significant disease challenges confronting commercial pig farming systems, introduction of a new feed additive that can enhance animal performance by improving growth and immune status represents a major opportunity. One such candidate is sialic acid (Sia), a diverse family of nine-carbon acidic sugar, present in various organs and body fluid, as well as an essential structural and functional constituent of brain ganglioside of humans and animals. Sias are key monosaccharide and biomarker of sialylated milk oligosaccharide (Sia-MOS’s), sialylated glycoproteins and glycolipids in milk and all vertebrate cells. Sias accomplish many critical endogenous functions by virtue of their physiochemical properties and via recognition by intrinsic receptors. Human milk sialylated glycoconjugates (Sia-GC’s) are bioactive compounds known to act as prebiotics that promote gut microbiota development, gut maturation, pathogen resistance, immunomodulation, anti-inflammation and neurodevelopment. However, the importance of Sia in pig health, especially in the growth, development, immunity of developing piglet and in pig production remains unknown. This review aims to critically discuss the current status of knowledge of the biology and nutritional role of Sia and Sia-GC’s on health of both female sow and newborn piglets.

Impact of dietary fibers in infant formulas on gut microbiota and the intestinal immune barrier

Human milk (HM) is the gold standard for the nutrition of infants. An important component of HM is human milk oligosaccharides (hMOs), which play an important role in gut microbiota colonization and gut immune barrier establishment, and thereby contribute to the maturation of the immune system in early life. Guiding these processes is important as disturbances have life-long health effects and can lead to the development of allergic diseases. Unfortunately, not all infants can be exclusively fed with HM. These infants are routinely fed with infant formulas that contain hMO analogs and other non-digestible carbohydrates (NDCs) to mimic the effects of hMOs. Currently, the hMO analogs 2'-fucosyllactose (2'-FL), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), and pectins are added to infant formulas; however, these NDCs cannot mimic all hMO functions and therefore new NDCs and NDC mixtures need to become available for specific groups of neonates like preterm and disease-prone neonates. In this review, we discuss human data on the beneficial effects of infant formula supplements such as the specific hMO analog 2'-FL and NDCs as well as their mechanism of effects like stimulation of microbiota development, maturation of different parts of the gut immune barrier and anti-pathogenic effects. Insights into the structure-specific mechanisms by which hMOs and NDCs exert their beneficial functions might contribute to the development of new tailored NDCs and NDC mixtures. We also describe the needs for new in vitro systems that can be used for research on hMOs and NDCs. The current data suggest that "tailored infant formulas" for infants of different ages and healthy statuses are needed to ensure a healthy development of the microbiota and the gut immune system of infants.

Adhesion of Helicobacter Species to the Human Gastric Mucosa: A Deep Look Into Glycans Role

Helicobacter species infections may be associated with the development of gastric disorders, such as gastritis, peptic ulcers, intestinal metaplasia, dysplasia and gastric carcinoma. Binding of these bacteria to the gastric mucosa occurs through the recognition of specific glycan receptors expressed by the host epithelial cells. This review addresses the state of the art knowledge on these host glycan structures and the bacterial adhesins involved in Helicobacter spp. adhesion to gastric mucosa colonization. Glycans are expressed on every cell surface and they are crucial for several biological processes, including protein folding, cell signaling and recognition, and host-pathogen interactions. Helicobacter pylori is the most predominant gastric Helicobacter species in humans. The adhesion of this bacterium to glycan epitopes present on the gastric epithelial surface is a crucial step for a successful colonization. Major adhesins essential for colonization and infection are the blood-group antigen-binding adhesin (BabA) which mediates the interaction with fucosylated H-type 1 and Lewis B glycans, and the sialic acid-binding adhesin (SabA) which recognizes the sialyl-Lewis A and X glycan antigens. Since not every H. pylori strain expresses functional BabA or SabA adhesins, other bacterial proteins are most probably also involved in this adhesion process, including LabA (LacdiNAc-binding adhesin), which binds to the LacdiNAc motif on MUC5AC mucin. Besides H. pylori, several other gastric non-Helicobacter pylori Helicobacters (NHPH), mainly associated with pigs (H. suis) and pets (H. felis, H. bizzozeronii, H. salomonis, and H. heilmannii), may also colonize the human stomach and cause gastric disease, including gastritis, peptic ulcers and mucosa-associated lymphoid tissue (MALT) lymphoma. These NHPH lack homologous to the major known adhesins involved in colonization of the human stomach. In humans, NHPH infection rate is much lower than in the natural hosts. Differences in the glycosylation profile between gastric human and animal mucins acting as glycan receptors for NHPH-associated adhesins, may be involved. The identification and characterization of the key molecules involved in the adhesion of gastric Helicobacter species to the gastric mucosa is important to understand the colonization and infection strategies displayed by different members of this genus.

Helicobacter pylori-targeting multiligand photosensitizer for effective antibacterial endoscopic photodynamic therapy

Helicobacter pylori (H. pylori) infection is closely associated with the development of gastric inflammatory diseases and cancer. However, the continued abuse and misuse of antibiotics has accelerated the spread of antibiotic-resistant strains, which poses a tremendous challenge for antibiotic-based H. pylori treatment. In this study, a H. pylori-targeting photodynamic therapy (PDT) system is proposed that multiple 3'-sialyllactose (3SL)-conjugated, poly-_l-lysine-based photosensitizer (p3SLP). p3SLP facilitates H. pylori-targeting PDT via the specific interaction between 3SL and sialic acid-binding adhesin (SabA) in the H. pylori membrane. p3SLP can be orally administered to H. pylori infected mice and irradiated using an endoscopic laser system. The gastrointestinal pathological analysis of the H. pylori-infected mice demonstrated significant H. pylori specific antibacterial effects of PDT without side effects to normal tissue. In addition, an anti-inflammatory response was observed at the site of infection after p3SLP treatment. Consequently, this study demonstrates the superior efficacy of anti-H. pylori PDT with p3SLP in H. pylori-infected mice, and this approach shows great potential for replacing antibiotic-based therapy.

Goat Milk Oligosaccharides: Their Diversity, Quantity, and Functional Properties in Comparison to Human Milk Oligosaccharides

Human milk is considered the golden standard in infant nutrition. Free oligosaccharides in human milk provide important health benefits. These oligosaccharides function as prebiotics, immune modulators, and pathogen inhibitors and were found to improve barrier function in the gut. Infant formulas nowadays often contain prebiotics but lack the specific functions of human milk oligosaccharides (hMOS). Milk from domesticated animals also contains milk oligosaccharides but at much lower levels and with less diversity. Goat milk contains significantly more oligosaccharides (gMOS) than bovine (bMOS) or sheep (sMOS) milk and also has a larger diversity of structures. This review summarizes structural studies, revealing a diversity of up to 77 annotated gMOS structures with almost 40 structures fully characterized. Quantitative studies of goat milk oligosaccharides range from 60 to 350 mg/L in mature milk and from 200 to 650 mg/L in colostrum. These levels are clearly lower than in human milk (5-20 g/L) but higher than in other domesticated dairy animals, e.g., bovine (30-60 mg/L) and sheep (20-40 mg/L). Finally, the review focuses on demonstrated and potential functionalities of gMOS. Some studies have shown anti-inflammatory effects of mixtures enriched in gMOS. Goat MOS also display prebiotic potential, particularly in stimulating growth of bifidobacteria preferentially. Although functional studies of gMOS are still limited, several structures are also found in human milk and have known functions as immune modulators and pathogen inhibitors. In conclusion, goat milk constitutes a promising alternative source for milk oligosaccharides, which can be used in infant formula.

In Love with Shaping You-Influential Factors on the Breast Milk Content of Human Milk Oligosaccharides and Their Decisive Roles for Neonatal Development

Human milk oligosaccharides (HMOs) are structurally versatile sugar molecules constituting the third major group of soluble components in human breast milk. Based on the disaccharide lactose, the mammary glands of future and lactating mothers produce a few hundreds of different HMOs implicating that their overall anabolism utilizes rather high amounts of energy. At first sight, it therefore seems contradictory that these sugars are indigestible for infants raising the question of why such an energy-intensive molecular class evolved. However, in-depth analysis of their molecular modes of action reveals that Mother Nature created HMOs for neonatal development, protection and promotion of health. This is not solely facilitated by HMOs in their indigestible form but also by catabolites that are generated by microbial metabolism in the neonatal gut additionally qualifying HMOs as natural prebiotics. This narrative review elucidates factors influencing the HMO composition as well as physiological roles of HMOs on their way through the infant body and within the gut, where a major portion of HMOs faces microbial catabolism. Concurrently, this work summarizes in vitro, preclinical and observational as well as interventional clinical studies that analyzed potential health effects that have been demonstrated by or were related to either human milk-derived or synthetic HMOs or HMO fractions.

Smart drug delivery against Helicobacter pylori: pectin-coated, mucoadhesive liposomes with antiadhesive activity and antibiotic cargo

The first step in the development of Helicobacter pylori pathogenicity is the receptor-mediated adhesion to the gastric epithelium. Inhibition of outer membrane proteins of H. pylori (e.g. BabA) by antiadhesive drugs will contribute to reduced recolonization and infection. Pectin from apple inhibits the BabA and LPS-mediated adhesion of H. pylori to human stomach cells. Pectin-coated liposomes with encapsulated amoxicillin were characterized for polydispersity, zeta potential, encapsulation efficiency, stability, and amoxicillin release. Coated liposomes did not influence the viability of AGS and HT29-MTX cells up to 100 μg/mL but exert cytotoxicity against H. pylori at 10 μg/mL. Pectin-coating of liposomes provoked direct interaction and subsequent binding of the particles to surface structures of H. pylori, and interaction with mucus from porcine stomach and mucus secreted by HT29-MTX cells. Laser scanning microscopy of H. pylori and AGS cells together with liposomes indicated co-aggregation. The mucoadhesive effect seems interesting as stomach cells are covered by a mucus layer. H. pylori is able to penetrate and cross the mucin rapidly to reach pH-neutral epithelium to escape the acidic environment, followed by interaction with epithelial cells. In summary, all experimental evidence is consistent with a specific interaction of pectin-coated liposomes with mucins and surface structures of H. pylori. As the coated liposomes show mucoadhesion to the negatively charged mucins, docking to stomach mucin, mucus penetration, and recognition of and adhesion to H. pylori, they can be considered a novel type of multifunctional drug carriers for local antibiotic therapy against H. pylori. KEY POINTS: • Smart, multifunctional mucoadhesive liposomes • Specific targeting against BabA/LPS of Helicobacter pylori • Inhibition of bacterial adhesion of H. pylori to human host cells • Release of antibiotic cargo.

Cholesteryl α-D-glucoside 6-acyltransferase enhances the adhesion of Helicobacter pylori to gastric epithelium

Helicobacter pylori, the most common etiologic agent of gastric diseases including gastric cancer, is auxotrophic for cholesterol and has to hijack it from gastric epithelia. Upon uptake, the bacteria convert cholesterol to cholesteryl 6′-O-acyl-α-D-glucopyranoside (CAG) to promote lipid raft clustering in the host cell membranes. However, how CAG appears in the host to exert the pathogenesis still remains ambiguous. Herein we identified hp0499 to be the gene of cholesteryl α-D-glucopyranoside acyltransferase (CGAT). Together with cholesteryl glucosyltransferase (catalyzing the prior step), CGAT is secreted via outer membrane vesicles to the host cells for direct synthesis of CAG. This significantly enhances lipid rafts clustering, gathers adhesion molecules (including Lewis antigens and integrins α5, β1), and promotes more bacterial adhesion. Furthermore, the clinically used drug amiodarone was shown as a potent inhibitor of CGAT to effectively reduce the bacterial adhesion, indicating that CGAT is a potential target of therapeutic intervention.

Jan et al. identify cholesteryl α-D- glucopyranoside acyltransferase as a key enzyme in Helicobacter pylori’s synthesis of cholesteryl 6’-O-acyl-α-D-glucopyranoside, which promotes bacterial adhesion. This study provides insights into the H. pylori-induced pathogenesis and therapeutic strategies against it.

Symposium review: Dairy-derived oligosaccharides-Their influence on host-microbe interactions in the gastrointestinal tract of infants

Oligosaccharides are the third most abundant component in human milk. It is widely accepted that they play several important protective, physiological, and biological roles, including selective growth stimulation of beneficial gut microbiota, inhibition of pathogen adhesion, and immune modulation. However, until recently, very few commercial products on the market have capitalized on these functions. This is mainly because the quantities of human milk oligosaccharides required for clinical trials have been unavailable. Recently, clinical studies have tested the potential beneficial effects of feeding infants formula containing 2'-fucosyllactose, which is the most abundant oligosaccharide in human milk. These studies have opened this field for further well-designed studies, which are required to fully understand the role of human milk oligosaccharides. However, one of the most striking features of human milk is its diversity of oligosaccharides, with over 200 identified to date. It may be that a mixture of oligosaccharides is even more beneficial to infants than a single structure. For this reason, the milk of domestic animals has become a focal point in recent years as an alternative source of complex oligosaccharides with associated biological activity. This review will focus specifically on free oligosaccharides found in bovine and caprine milk and the biological roles associated with such structures. These dairy streams are ideal sources of oligosaccharides, given their wide availability and use in so many regularly consumed dairy products. The aim of this review was to provide an overview of research into the functional role of bovine and caprine milk oligosaccharides in host-microbial interactions in the gut and provide current knowledge related to the isolation of oligosaccharides as ingredients for incorporation in functional or medical foods.

BabA and LPS inhibitors against Helicobacter pylori: pectins and pectin-like rhamnogalacturonans as adhesion blockers

The first step in the development of Helicobacter pylori pathogenicity is receptor-mediated adhesion to gastric epithelium. Adhesins of H. pylori not only enable colonisation of the epithelium, with BabA interacting with Lewis^b, but also interaction of lipopolysaccharide (LPS) with galectin-3 contributes to attachment of H. pylori to the host cells. Anti-adhesive compounds against H. pylori have been described, but specific analytical assays for pinpointing the interaction with BabA are limited. LPS-galectin-3 inhibitors have not been described until now. A sandwich ELISA with recombinant BabA₅₄₇-6K was developed to investigate the interaction of BabA with Lewis^b-HSA. Isothermal titration calorimetry gave thermodynamic information on the interaction between BabA, Lewis^b-HSA and anti-adhesive compounds. A highly esterified rhamnogalacturonan from Abelmoschus esculentus inhibited the adhesion of H. pylori to adherent gastric adenocarcinoma (AGS) cells (IC₅₀ 550 μg/mL) and interacted with BabA (IC₅₀ 17 μg/mL). Pectins with similar rhamnogalacturonan structure showed weak anti-adhesive activity. Highly branched rhamnogalacturonans with low uronic acid content and high degree of esterification are potent BabA inhibitors. BabA represents a promising target for the development of anti-adhesive drugs against H. pylori. The rhamnogalacturonan influenced also the binding affinity of H. pylori to recombinant galectin-3 in a concentration-dependent manner with an IC₅₀ of 222 μg/mL. Similar effects were obtained with pectin from apple fruits, while pectins from other sources were inactive.

Oligosaccharides Isolated from MGO™ Manuka Honey Inhibit the Adhesion of Pseudomonas aeruginosa, Escherichia Coli O157:H7 and Staphylococcus Aureus to Human HT-29 cells

Historically, honey is known for its anti-bacterial and anti-fungal activities and its use for treatment of wound infections. Although this practice has been in place for millennia, little information exists regarding which manuka honey components contribute to the protective nature of this product. Given that sugar accounts for over 80% of honey and up to 25% of this sugar is composed of oligosaccharides, we have investigated the anti-infective activity of manuka honey oligosaccharides against a range of pathogens. Initially, oligosaccharides were extracted from a commercially-available New Zealand manuka honey-MGO™ Manuka Honey (Manuka Health New Zealand Ltd)-and characterized by High pH anion exchange chromatography coupled with pulsed amperiometric detection. The adhesion of specific pathogens to the human colonic adenocarcinoma cell line, HT-29, was then assessed in the presence and absence of these oligosaccharides. Manuka honey oligosaccharides significantly reduced the adhesion of Escherichia coli O157:H7 (by 40%), Staphylococcus aureus (by 30%), and Pseudomonas aeruginosa (by 52%) to HT-29 cells. This activity was then proven to be concentration dependent and independent of bacterial killing. This study identifies MGO™ Manuka Honey as a source of anti-infective oligosaccharides for applications in functional foods aimed at lowering the incidence of infectious diseases.

Engineering of CHO cells for the production of vertebrate recombinant sialyltransferases

Background

Sialyltransferases (SIATs) are a family of enzymes that transfer sialic acid (Sia) to glycan chains on glycoproteins, glycolipids, and oligosaccharides. They play key roles in determining cell–cell and cell-matrix interactions and are important in neuronal development, immune regulation, protein stability and clearance. Most fully characterized SIATs are of mammalian origin and these have been used for in vitro and in vivo modification of glycans. Additional versatility could be achieved by the use of animal SIATs from other species that live in much more variable environments. Our aim was to generate a panel of stable CHO cell lines expressing a range of vertebrate SIATs with different physicochemical and functional properties.

Methods

The soluble forms of various animal ST6Gal and ST3Gal enzymes were stably expressed from a Gateway-modified secretion vector in CHO cells. The secreted proteins were IMAC-purified from serum-free media. Functionality of the protein was initially assessed by lectin binding to the host CHO cells. Activity of purified proteins was determined by a number of approaches that included a phosphate-linked sialyltransferase assay, HILIC-HPLC identification of sialyllactose products and enzyme-linked lectin assay (ELLA).

Results

A range of sialyltransferase from mammals, birds and fish were stably expressed in CHO Flp-In cells. The stable cell lines expressing ST6Gal1 modify the glycans on the surface of the CHO cells as detected by fluorescently labelled lectin microscopy. The catalytic domains, as isolated by Ni Sepharose from culture media, have enzymatic activities comparable to commercial enzymes. Sialyllactoses were identified by HILIC-HPLC on incubation of the enzymes from lactose or whey permeate. The enzymes also increased SNA-I labelling of asialofetuin when incubated in a plate format.

Conclusion

Stable cell lines are available that may provide options for the in vivo sialylation of glycoproteins. Proteins are active and should display a variety of biological and physicochemical properties based on the animal source of the enzyme.

Sialylated Oligosaccharides and Glycoconjugates of Human Milk. The Impact on Infant and Newborn Protection, Development and Well-Being

Human milk not only has nutritional value, but also provides a wide range of biologically active molecules, which are adapted to meet the needs of newborns and infants. Mother’s milk is a source of sialylated oligosaccharides and glycans that are attached to proteins and lipids, whose concentrations and composition are unique. Sialylated human milk glycoconjugates and oligosaccharides enrich the newborn immature immune system and are crucial for their proper development and well-being. Some of the milk sialylated oligosaccharide structures can locally exert biologically active effects in the newborn’s and infant’s gut. Sialylated molecules of human milk can be recognized and bound by sialic acid-dependent pathogens and inhibit their adhesion to the epithelial cells of newborns and infants. A small amount of intact sialylated oligosaccharides can be absorbed from the intestine and remain in the newborn’s circulation in concentrations high enough to modulate the immunological system at the cellular level and facilitate proper brain development during infancy. Conclusion: The review summarizes the current state of knowledge on sialylated human milk oligosaccharides and glycoconjugates, discusses the significance of sialylated structures of human milk in newborn protection and development, and presents the advantages of human milk over infant formula.

Carbohydrate-Dependent and Antimicrobial Peptide Defence Mechanisms Against Helicobacter pylori Infections

The human stomach is a harsh and fluctuating environment for bacteria with hazards such as gastric acid and flow through of gastric contents into the intestine. H. pylori gains admission to a stable niche with nutrient access from exudates when attached to the epithelial cells under the mucus layer, whereof adherence to glycolipids and other factors provides stable and intimate attachment. To reach this niche, H. pylori must overcome mucosal defence mechanisms including the continuously secreted mucus layer, which provides several layers of defence: (1) mucins in the mucus layer can bind H. pylori and transport it away from the gastric niche with the gastric emptying, (2) mucins can inhibit H. pylori growth, both via glycans that can have antibiotic like function and via an aggregation-dependent mechanism, (3) antimicrobial peptides (AMPs) have antimicrobial activity and are retained in a strategic position in the mucus layer and (4) underneath the mucus layer, the membrane-bound mucins provide a second barrier, and can function as releasable decoys. Many of these functions are dependent on H. pylori interactions with host glycan structures, and both the host glycosylation and concentration of antimicrobial peptides change with infection and inflammation, making these interactions dynamic. Here, we review our current understanding of mucin glycan and antimicrobial peptide-dependent host defence mechanisms against H. pylori infection.

3'-Sialyllactose as an inhibitor of p65 phosphorylation ameliorates the progression of experimental rheumatoid arthritis

Background and Purpose

3′‐Sialyllactose (3′‐SL) is a safe compound that is present in high levels in human milk. Although it has anti‐inflammatory properties and supports immune homeostasis, its effect on collagen‐induced arthritis (CIA) is unknown. In this study, we investigated the prophylactic and therapeutic effect of 3′‐SL on the progression of rheumatoid arthritis (RA) in in vitro and in vivo models.

Experimental Approach

The anti‐arthritic effect of 3′‐SL was analysed with fibroblast‐like synoviocytes in vitro and an in vivo mouse model of CIA. RT‐PCR, Western blotting and ELISA were performed to evaluate its effects in vitro. Histological analysis of ankle and knee joints of mice with CIA was performed using immunohistochemistry, as well as safranin‐O and haematoxylin staining.

Key Results

3′‐SL markedly alleviated the severity of CIA in the mice by reducing paw swelling, clinical scores, incidence rate, serum levels of inflammatory cytokines and autoantibody production. Moreover, 3′‐SL reduced synovitis and pannus formation and suppressed cartilage destruction by blocking secretion of chemokines, pro‐inflammatory cytokines, https://en.wikipedia.org/wiki/Matrix_metalloproteinases and osteoclastogenesis via NF‐κB signalling. Notably, phosphorylation of p65, which is a key protein in the NF‐κB signalling pathway, was totally blocked by 3′‐SL in the RA models.

Conclusions and Implications

3′‐SL ameliorated pathogenesis of CIA by suppressing catabolic factor expression, proliferation of inflammatory immune cells and osteoclastogenesis. These effects were mediated via blockade of the NF‐κB signalling pathway. Therefore, 3′‐SL exerted prophylactic and therapeutic effects and could be a novel therapeutic agent for the treatment of RA.

Developments in strategies for Quorum Sensing virulence factor inhibition to combat bacterial drug resistance

Quorum sensing (QS) is a complex bacterial intercellular communication system. It is mediated by molecules called auto-inducers (AIs) and allows coordinated responses to a variety of environmental signals by inducing alterations in gene expression. Communication through QS can tremendously stimulate the pathogenicity and virulence via multiple mechanisms in pathogenic bacteria. The present review explores the major types of multitudinous QS systems known in Gram-positive and Gram-negative bacteria and their roles in bacterial pathogenesis and drug resistance. Because bacterial resistance to antibiotics is increasingly becoming a significant clinical challenge to human health; alternate strategies to combat drug resistance are warranted. Targeting bacterial pathogenicity by interruptions in QS using natural QS inhibitors and synthetic quorum-quenching analogs are being increasingly considered for development of next generation antimicrobials. The review highlights the recent advancements in discovery of promising new QS modulators and their efficiency in controlling infections caused by multidrug-resistant bacterial pathogens.

Broad-spectrum neutralization of avian influenza viruses by sialylated human milk oligosaccharides: in vivo assessment of 3'-sialyllactose against H9N2 in chickens

Two sialylated human milk oligosaccharides (SHMOs) 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) were accessed for their possible antiviral activity against six different subtypes of thirteen avian influenza (AI) viruses in vitro. 3'-SL exhibited promising antiviral activity against almost all subtypes of tested AI viruses in hemagglutination inhibition assay, whereas 6'-SL showed activity against few selected H1N1, H1N2, and H3N2 subtype strains. 3'-SL has minimum inhibitory concentration values of 15.62 mM or less in more than half of the viruses examined. 3'-SL also showed effective inactivation of H9N2 Korea isolate (A/Chicken/Korea/MS96/1996) at 12.5 mM concentration in Madin Darby Canine Kidney (MDCK) cell line. Thus, 3'-SL was further studied for in vivo study against H9N2 virus in pathogen free chicken experiment models. In vivo study exhibited improved clinical symptoms on H9N2 infected chickens when treated with 3'-SL. Moreover, treating chickens with 3'-SL resulted in complete elimination of H9N2 viruses within 24 h of virus infection (0.8 HAU of H9N2). Indirect ELISA assay confirmed complete wash-out of H9N2 viruses from the colon after neutralization by 3'-SL without entering the blood stream. These in vivo results open up possible applications of 3'-SL for the prevention of AI virus infections in birds by a simple cleansing mechanism.

Innovative Solutions to Sticky Situations: Antiadhesive Strategies for Treating Bacterial Infections

Bacterial adherence to host tissue is an essential process in pathogenesis, necessary for invasion and colonization and often required for the efficient delivery of toxins and other bacterial effectors. As existing treatment options for common bacterial infections dwindle, we find ourselves rapidly approaching a tipping point in our confrontation with antibiotic-resistant strains and in desperate need of new treatment options. Bacterial strains defective in adherence are typically avirulent and unable to cause infection in animal models. The importance of this initial binding event in the pathogenic cascade highlights its potential as a novel therapeutic target. This article seeks to highlight a variety of strategies being employed to treat and prevent infection by targeting the mechanisms of bacterial adhesion. Advancements in this area include the development of novel antivirulence therapies using small molecules, vaccines, and peptides to target a variety of bacterial infections. These therapies target bacterial adhesion through a number of mechanisms, including inhibition of pathogen receptor biogenesis, competition-based strategies with receptor and adhesin analogs, and the inhibition of binding through neutralizing antibodies. While this article is not an exhaustive description of every advancement in the field, we hope it will highlight several promising examples of the therapeutic potential of antiadhesive strategies.

Anti-Helicobacter pylori activity of crude N-acetylneuraminic acid isolated from glycomacropeptide of whey

Helicobacter pylori colonizes the gastric mucosa of about half of the world's population, causing chronic gastritis and gastric cancer. An increasing emergence of antibiotic-resistant H. pylori arouses demand on alternative non-antibiotic-based therapies. In this study, we freshly prepared crude N-acetylneuraminic acid obtained from glycomacropeptide (G-NANA) of whey through a neuraminidase-mediated reaction and evaluated its antibacterial ability against H. pylori and H. felis. Overnight cultures of the H. pylori were diluted with fresh media and different concentrations (1-150 mg/mL) of crude G-NANA were added directly to the culture tube. Bacterial growth was evaluated by measuring the optical density of the culture medium and the number of viable bacteria was determined by a direct count of the colony forming units (CFU) on agar plates. For the in vivo study, mice were orally infected with 100 µL (5×10(8) cfu/mL) of H. felis four times at a day's interval, accompanied by a daily administration of crude G-NANA or vehicle. A day after the last infection, the mice were daily administered the crude G-NANA (0, 75, and 300 mg/mL) for 10 days and euthanized. Their stomachs were collected and bacterial colonization was determined by quantitative real-time PCR. Crude G-NANA inhibited H. pylori's growth and reduced the number of viable bacteria in a dose-dependent manner. Furthermore, crude G-NANA inhibited bacterial colonization in the mice. These results showed that crude G-NANA has antibacterial activity against Helicobacter and demonstrated its therapeutic potential for the prevention of chronic gastritis and gastric carcinogenesis induced by Helicobacter infection in humans.

Clinical applications of bioactive milk components

Milk represents a unique resource for translational medicine: It contains a rich pool of biologically active molecules with demonstrated clinical benefits. The ongoing characterization of the mechanistic process through which milk components promote development and immunity has revealed numerous milk-derived compounds with potential applications as clinical therapies in infectious and inflammatory disease, cancer, and other conditions. Lactoferrin is an effective antimicrobial and antiviral agent in high-risk patient populations and a potentially potent adjuvant to chemotherapy in lung cancer. Enteric nutrition formulas supplemented with transforming growth factor β, a milk cytokine, have been shown to promote remission in pediatric Crohn's disease. A number of milk glycans, including human milk oligosaccharides, show promise in preclinical studies as antimicrobial and anti-inflammatory agents. While active preclinical investigations of human milk may soon result in large-scale production of human milk molecules, bovine milk components in many instances represent a practical source of bioactive milk compounds for use in clinical trials. This review summarizes current efforts to translate the compounds derived from human and bovine milk into effective clinical therapies. These efforts suggest a common pathway for the translation of milk-derived compounds into clinical applications.

Dietary amelioration of Helicobacter infection

We review herein the basis for using dietary components to treat and/or prevent Helicobacter pylori infection, with emphasis on (a) work reported in the last decade, (b) dietary components for which there is mechanism-based plausibility, and (c) components for which clinical results on H pylori amelioration are available. There is evidence that a diet-based treatment may reduce the levels and/or the virulence of H pylori colonization without completely eradicating the organism in treated individuals. This concept was endorsed a decade ago by the participants in a small international consensus conference held in Honolulu, Hawaii, USA, and interest in such a diet-based approach has increased dramatically since then. This approach is attractive in terms of cost, treatment, tolerability, and cultural acceptability. This review, therefore, highlights specific foods, food components, and food products, grouped as follows: bee products (eg, honey and propolis); probiotics; dairy products; vegetables; fruits; oils; essential oils; and herbs, spices, and other plants. A discussion of the small number of clinical studies that are available is supplemented by supportive in vitro and animal studies. This very large body of in vitro and preclinical evidence must now be followed up with rationally designed, unambiguous human trials.

Inhibition of adhesion of intestinal pathogens (Escherichia coli, Vibrio cholerae, Campylobacter jejuni, and Salmonella Typhimurium) by common oligosaccharides

Inhibition of the binding of pathogenic adhesins to host glycans by suitable oligosaccharides forms the basis of antiadhesion therapies. Experiments were carried out to study the inhibition capability of oligosaccharides on the adhesion of four microorganisms (Escherichia coli, Vibrio cholerae, Campylobacter jejuni, and Salmonella Typhimurium) to HT-29 cells. Results showed that, in the absence of oligosaccharides, all of the four pathogens efficiently adhered to the cells. Cell adhesion with different bacteria was inhibited by distinct oligosaccharides (e.g., the adhesion number relative to control of V. cholerae could be significantly decreased by pectin oligosaccharide and chitooligosaccharide to about 16.1% and 18.9%, respectively). Saturation studies showed that the extent of antiadhesive effect for most of the suitable carbohydrates was dependent on their concentration. The observations from the study suggest that various carbohydrates may have antiadhesive activity and may be useful in future therapeutic study.

Human Milk Oligosaccharides (HMOS): Structure, Function, and Enzyme-Catalyzed Synthesis

The important roles played by human milk oligosaccharides (HMOS), the third major component of human milk, in the health of breast-fed infants have been increasingly recognized, as the structures of more than 100 different HMOS have now been elucidated. Despite the recognition of the various functions of HMOS as prebiotics, antiadhesive antimicrobials, and immunomodulators, the roles and the applications of individual HMOS species are less clear. This is mainly due to the limited accessibility to large amounts of individual HMOS in their pure forms. Current advances in the development of enzymatic, chemoenzymatic, whole-cell, and living-cell systems allow for the production of a growing number of HMOS in increasing amounts. This effort will greatly facilitate the elucidation of the important roles of HMOS and allow exploration into the applications of HMOS both as individual compounds and as mixtures of defined structures with desired functions. The structures, functions, and enzyme-catalyzed synthesis of HMOS are briefly surveyed to provide a general picture about the current progress on these aspects. Future efforts should be devoted to elucidating the structures of more complex HMOS, synthesizing more complex HMOS including those with branched structures, and developing HMOS-based or HMOS-inspired prebiotics, additives, and therapeutics.

Functional role and mechanisms of sialyllactose and other sialylated milk oligosaccharides

Human milk is a rich source of oligosaccharides. Acidic oligosaccharides, such as sialyllactose (SL), contain sialic acid (SA) residues. In human milk, approximately 73% of SA is bound to oligosaccharides, whereas only 3% is present in free form. Oligosaccharides are highly resistant to hydrolysis in the gastrointestinal tract. Only a small portion of the available oligosaccharides in breast milk is absorbed in the neonatal small intestine. SL and sialylated oligosaccharides are thought to have significant health benefits for the neonate, because of their roles in supporting resistance to pathogens, gut maturation, immune function, and cognitive development. The need for SA to allow proper development during the neonatal period is thought to exceed the endogenous synthesis. Therefore, these structures are important nutrients for the neonate. Based on the potential benefits, SL and sialylated oligosaccharides may be interesting components for application in infant nutrition. Once the hurdle of limited availability of these oligosaccharides has been overcome, their functionality can be explored in more detail, and supplementation of infant formula may become feasible.

Antiadhesive properties of arabinogalactan protein from ribes nigrum seeds against bacterial adhesion of Helicobacter pylori

Fruit extracts from black currants (Ribes nigrum L.) are traditionally used for treatment of gastritis based on seed polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach cells. For detailed investigations an arabinogalactan protein (F2) was isolated from seeds and characterized concerning molecular weight, carbohydrate, amino acid composition, linkage, configuration and reaction with β-glucosyl Yariv. Functional testing of F2 was performed by semiquantitative in situ adhesion assay on sections of human gastric mucosa and by quantitative in vitro adhesion assay with FITC-labled H. pylori strain J99 and human stomach AGS cells. Bacterial adhesins affected were identified by overlay assay with immobilized ligands. ¹²⁵I-radiolabeled F2 served for binding studies to H. pylori and interaction experiments with BabA and SabA. F2 had no cytotoxic effects against H. pylori and AGS cells; but inhibited bacterial binding to human gastric cells. F2 inhibited the binding of BabA and fibronectin-binding adhesin to its specific ligands. Radiolabeled F2 bound non-specifically to different strains of H. pylori; and to BabA deficient mutant. F2 did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors. From these data the non-specific interactions between F2 and the H. pylori lead to moderate antiadhesive effects.

Antiadhesive properties of Abelmoschus esculentus (Okra) immature fruit extract against Helicobacter pylori adhesion

BACKGROUND

Traditional Asian and African medicine use immature okra fruits (Abelmoschus esculentus) as mucilaginous food to combat gastritis. Its effectiveness is due to polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach tissue. The present study investigates the antiadhesive effect in mechanistic detail.

METHODOLOGY

A standardized aqueous fresh extract (Okra FE) from immature okra fruits was used for a quantitative in vitro adhesion assay with FITC-labled H. pylori J99, 2 clinical isolates, AGS cells, and fluorescence-activated cell sorting. Bacterial adhesins affected by FE were pinpointed using a dot-blot overlay assay with immobilized Lewis(b), sialyl-Lewis(a), H-1, laminin, and fibronectin. (125)I-radiolabeled Okra FE polymer served for binding studies to different H. pylori strains and interaction experiments with BabA and SabA. Iron nanoparticles with different coatings were used to investigate the influence of the charge-dependence of an interaction on the H. pylori surface.

PRINCIPAL FINDINGS

Okra FE dose-dependently (0.2 to 2 mg/mL) inhibited H. pylori binding to AGS cells. FE inhibited the adhesive binding of membrane proteins BabA, SabA, and HpA to its specific ligands. Radiolabeled compounds from FE bound non-specifically to different strains of H. pylori, as well as to BabA/SabA deficient mutants, indicating an interaction with a still-unknown membrane structure in the vicinity of the adhesins. The binding depended on the charge of the inhibitors. Okra FE did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors.

CONCLUSION

Non-specific interactions between high molecular compounds from okra fruits and the H. pylori surface lead to strong antiadhesive effects.

Transcriptional response of HT-29 intestinal epithelial cells to human and bovine milk oligosaccharides

Human milk oligosaccharides (HMO) have been shown to interact directly with immune cells. However, large quantities of HMO are required for intervention or clinical studies, but these are unavailable in most cases. In this respect, bovine milk is potentially an excellent source of commercially viable analogues of these unique molecules. In the present study, we compared the transcriptional response of colonic epithelial cells (HT-29) to the entire pool of HMO and bovine colostrum oligosaccharides (BCO) to determine whether the oligosaccharides from bovine milk had effects on gene expression that were similar to those of their human counterparts. Gene set enrichment analysis of the transcriptional data revealed that there were a number of similar biological processes that may be influenced by both treatments including a response to stimulus, signalling, locomotion, and multicellular, developmental and immune system processes. For a more detailed insight into the effects of milk oligosaccharides, the effect on the expression of immune system-associated glycogenes was chosen as a case study when performing validation studies. Glycogenes in the current context are genes that are directly or indirectly regulated in the presence of glycans and/or glycoconjugates. RT-PCR analysis revealed that HMO and BCO influenced the expression of cytokines (IL-1β, IL-8, colony-stimulating factor 2 (granulocyte–macrophage) (GM-CSF2), IL-17C and platelet factor 4 (PF4)), chemokines (chemokine (C–X–C motif) ligand 1 (CXCL1), chemokine (C–X–C motif) ligand 3 (CXCL3), chemokine (C–C motif) ligand 20 (CCL20), chemokine (C–X–C motif) ligand 2 (CXCL2), chemokine (C–X–C motif) ligand 6 (CXCL6), chemokine (C–C motif) ligand 5 (CCL5), chemokine (C–X3–C motif) ligand 1 (CX3CL1) and CXCL2) and cell surface receptors (interferon γ receptor 1 (IFNGR1), intercellular adhesion molecule-1 (ICAM-1), intercellular adhesion molecule-2 (ICAM-2) and IL-10 receptor α (IL10RA)). The present study suggests that milk oligosaccharides contribute to the development and maturation of the intestinal immune response and that bovine milk may be an attractive commercially viable source of oligosaccharides for such applications.

Anti-adhesion methods as novel therapeutics for bacterial infections

Anti-adhesion therapies for bacterial infections offer an alternative to antibiotics, with those therapies bacteria are not killed but are prevented from causing harm to a host by inhibiting adherence to host cells and tissues, a prerequisite for the majority of infectious diseases. The mechanisms of these potential therapeutic agents include inhibition of adhesins and their host receptors, vaccination with adhesins or analogs, use of probiotics and dietary supplements that interfere with receptor-adhesin interactions, subminimal inhibitory concentrations of antibiotics and manipulation of hydrophobic interactions. Once developed, these drugs will contribute to the arsenal for fighting infectious disease in the future, potentially subverting antibiotic resistance.

Catechins and Sialic Acid Attenuate Helicobacter pylori-Triggered Epithelial Caspase-1 Activity and Eradicate Helicobacter pylori Infection

The inflammasome/caspase-1 signaling pathway in immune cells plays a critical role in bacterial pathogenesis; however, the regulation of this pathway in the gastric epithelium during Helicobacter pylori infection is yet to be elucidated. Here, we investigated the effect of catechins (CAs), sialic acid (SA), or combination of CA and SA (CASA) on H. pylori-induced caspase-1-mediated epithelial damage, as well as H. pylori colonization in vitro (AGS cells) and in vivo (BALB/c mice). Our results indicate that the activity of caspase-1 and the expression of its downstream substrate IL-1β were upregulated in H. pylori-infected AGS cells. In addition, we observed increased oxidative stress, NADPH oxidase gp91phox, CD68, caspase-1/IL-1β, and apoptosis, but decreased autophagy, in the gastric mucosa of H. pylori-infected mice. We have further demonstrated that treatment with CASA led to synergistic anti-H. pylori activity and was more effective than treatment with CA or SA alone. In particular, treatment with CASA for 10 days eradicated H. pylori infection in up to 95% of H. pylori-infected mice. Taken together, we suggest that the pathogenesis of H. pylori involves a gastric epithelial inflammasome/caspase-1 signaling pathway, and our results show that CASA was able to attenuate this pathway and effectively eradicate H. pylori infection.

Evaluation of the anti-adhesive effect of milk fat globule membrane glycoproteins on Helicobacter pylori in the human NCI-N87 cell line and C57BL/6 mouse model

BACKGROUND

 The interest in non-antibiotic therapies for Helicobacter pylori infections in man has considerably grown because increasing numbers of antibiotic-resistant strains are being reported. Intervention at the stage of bacterial attachment to the gastric mucosa could be an approach to improve the control/eradication rate of this infection.

MATERIALS AND METHODS

 Fractions of purified milk fat globule membrane glycoproteins were tested in vitro for their cytotoxic and direct antibacterial effect. The anti-adhesive effect on H. pylori was determined first in a cell model using the mucus-producing gastric epithelial cell line NCI-N87 and next in the C57BL/6 mouse model after dosing at 400 mg/kg protein once or twice daily from day -2 to day 4 post-infection. Bacterial loads were determined by using quantitative real-time PCR and the standard plate count method.

RESULTS

 The milk fat globule membrane fractions did not show in vitro cytotoxicity, and a marginal antibacterial effect was demonstrated for defatted milk fat globule membrane at 256 μg/mL. In the anti-adhesion assay, the results varied from 56.0 ± 5.3% inhibition for 0.3% crude milk fat globule membrane to 79.3 ± 3.5% for defatted milk fat globule membrane. Quite surprisingly, in vivo administration of the same milk fat globule membrane fractions did not confirm the anti-adhesive effects and even caused an increase in bacterial load in the stomach.

CONCLUSIONS

 The promising anti-adhesion in vitro results could not be confirmed in the mouse model, even after the highest attainable exposure. It is concluded that raw or defatted milk fat globule membrane fractions do not have any prophylactic or therapeutic potential against Helicobacter infection.

Anti-infective bovine colostrum oligosaccharides: Campylobacter jejuni as a case study

Campylobacter jejuni is the leading cause of acute bacterial infectious diarrhea in humans. Unlike in humans, C. jejuni is a commensal within the avian host. Heavily colonized chickens often fail to display intestinal disease, and no cellular attachment or invasion has been demonstrated in-vivo. Recently, researchers have shown that the reason for the attenuation of C. jejuni virulence may be attributed to the presence of chicken intestinal mucus and more specifically chicken mucin. Since mucins are heavily glycosylated molecules this observation would suggest that glycan-based compounds may act as anti-infectives against C. jejuni. Considering this, we have investigated naturally sourced foods for potential anti-infective glycans. Bovine colostrum rich in neutral and acidic oligosaccharides has been identified as a potential source of anti-infective glycans. In this study, we tested oligosaccharides isolated and purified from the colostrum of Holstein Friesian cows for anti-infective activity against a highly invasive strain of C. jejuni. During our initial studies we structurally defined 37 bovine colostrum oligosaccharides (BCO) by HILIC-HPLC coupled with exoglycosidase digests and off-line mass spectroscopy, and demonstrated the ability of C. jejuni to bind to some of these structures, in-vitro. We also examined the effect of BCO on C. jejuni adhesion to, invasion of and translocation of HT-29 cells. BCO dramatically reduced the cellular invasion and translocation of C. jejuni, in a concentration dependent manner. Periodate treatment of the BCO prior to inhibition studies resulted in a loss of the anti-infective activity of the glycans suggesting a direct oligosaccharide-bacterial interaction. This was confirmed when the BCO completely prevented C. jejuni binding to chicken intestinal mucin, in-vitro. This study builds a strong case for the inclusion of oligosaccharides sourced from cow's milk in functional foods. However, it is only through further understanding the structure and function of milk oligosaccharides that such compounds can reach their potential as food ingredients.

Urinary excretion of in vivo ¹³C-labelled milk oligosaccharides in breastfed infants

Recent observations indicate that human milk oligosaccharides (HMO) are involved in a variety of physiological processes in infants. Their metabolic fate, however, is virtually unknown. We investigated metabolic aspects in infants after endogenous 13C-labelling of HMO. An oral bolus of natural and 13C-labelled galactose (Gal; 23 g Gal+4 g 13C-Gal) was given to ten lactating women. Aliquots of milk at each nursing as well as breath samples from the mothers and urine from their infants were collected over 36 h. The 13C-enrichment of HMO and their renal excretion was determined by isotope ratio-MS; characterisation was achieved by fast atom bombardment-MS. After the Gal bolus was given, an immediate 13C-enrichment in milk and in infants' urine was observed which lasted 36 h. Mass spectrometric analysis of 13C-enriched urinary fractions confirmed the excretion of a variety of neutral and acidic HMO without metabolic modification of their structures. Components with glucose split off at the reducing end were also detectable. Quantitative data regarding the infants' intake of lacto-N-tetraose and its monofucosylated derivative lacto-N-fucopentaose II ranged from 50 to 160 mg with each suckling, respectively; renal excretion of both components varied between 1 and 3 mg/d. Since the intake of individual HMO by the infants was in the range of several hundred mg per suckling, i.e. several g/d, and some of these components were excreted in mg amounts as intact HMO with the infants' urine, not only local but also systemic effects might be expected.

The influence of milk oligosaccharides on microbiota of infants: opportunities for formulas

In addition to a nutritive role, human milk also guides the development of a protective intestinal microbiota in the infant. Human milk possesses an overabundance of complex oligosaccharides that are indigestible by the infant yet are consumed by microbial populations in the developing intestine. These oligosaccharides are believed to facilitate enrichment of a healthy infant gastrointestinal microbiota, often associated with bifidobacteria. Advances in glycomics have enabled precise determination of milk glycan structures as well as identification of the specific glycans consumed by various gut microbes. Furthermore, genomic analysis of bifidobacteria from infants has revealed specific genetic loci related to milk oligosaccharide import and processing, suggesting coevolution between the human host, milk glycans, and the microbes they enrich. This review discusses the current understanding of how human milk oligosaccharides interact with the infant microbiota and examines the opportunities for translating this knowledge to improve the functionality of infant formulas.

The role of bacteria in the pathogenesis of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) have features that suggest bacterial involvement, and all genetic models of inflammatory bowel disease (IBD) require the presence of commensal bacteria. CD is associated with innate immune response genes such as NOD2/CARD15 and the autophagy genes ATG16L1 and IRGM. However, IBD responds to immunosuppression, suggesting that any bacteria involved are not acting as conventional pathogens. Molecular techniques are rapidly advancing our knowledge of the gut microbiota. In CD there is reduced diversity, and notably a reduction in the probiotic Faecalibacterium prausnitzii, the presence of which in the terminal ileum is associated with a reduced risk of recurrence following surgery. There is also a consistent increase in mucosa-associated Escherichia coli with an "adherent and invasive" phenotype, which allows them to replicate inside macrophages and induce granulomas. Speculation that CD could be caused by the Mycobacterium avium subspecies paratuberculosis (MAP) continues. The response to antitumor necrosis factor treatments suggests that, if relevant at all, MAP is not acting as a conventional pathogen. However, there is increased colonization by MAP in CD, and there is evidence that it could have an indirect effect mediated by the suppression of macrophage function. UC relapse is frequently associated with infection by pathogens, but there is less evidence for involvement of a specific bacterial species. Poor barrier integrity followed by an inflammatory reaction to bacterial components, with chronicity maintained by an autoimmune process, seems a plausible pathogenic model. Bacterial theories of pathogenesis are now becoming testable by targeted therapeutic interventions.

Paradigm shift in discovering next-generation anti-infective agents: targeting quorum sensing, c-di-GMP signaling and biofilm formation in bacteria with small molecules

Small molecules that can attenuate bacterial toxin production or biofilm formation have the potential to solve the bacteria resistance problem. Although several molecules, which inhibit bacterial cell-to-cell communication (quorum sensing), biofilm formation and toxin production, have been discovered, there is a paucity of US FDA-approved drugs that target these processes. Here, we review the current understanding of quorum sensing in important pathogens such as Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus and provide examples of experimental molecules that can inhibit both known and unknown targets in bacterial virulence factor production and biofilm formation. Structural data for protein targets that are involved in both quorum sensing and cyclic diguanylic acid signaling are needed to aid the development of molecules with drug-like properties in order to target bacterial virulence factors production and biofilm formation.

Mass spectrometric methods for analysis of oligosaccharides in human milk

Establishing the analytical platforms for characterizing human milk oligosaccharides is important to fully assess their specific functionalities. The characterization of these biomolecules, however, is still considered challenging, owing to their overall complexity and diversity. Addressed here are the technical difficulties with an emphasis on the application of mass spectrometry to rapidly profile and quantify human milk oligosaccharides. Fundamental concepts and improvements in instrumentation and an overview of the biological functions and structures of these compounds are also discussed. Results reveal that small-chain oligosaccharides, evident in abundance in the early stage of lactation, are selectively consumed by specific stains of Bifidobacterium longum biovar, infantis.

In-vitro interaction of l-dopa with bacterial adhesins of Helicobacter pylori: an explanation for clinicial differences in bioavailability?

Objectives

Recent investigations on the pharmacokinetics of levodopa (l-dopa) indicated that the presence of Helicobacter pylori in patients with Parkinson's disease, orally treated with l-dopa, influences the absorption of this compound, which consequently leads to decreased plasma levels. Therefore this work aims to study a potential in-vitro interaction of l-dopa with H. pylori and its surface adhesins.

Methods

Solutions containing l-dopa of different concentrations were incubated with H. pylori at different bacterial densities and time intervals. Free l-dopa was quantified from the incubation supernatants by HPLC. A flow cytometric assay with fluorescence labelled H. pylori was used to investigate the influence of l-dopa on the bacterial adhesion of H. pylori: FITC-labelled bacteria were pre-incubated with l-dopa, followed by incubation with gastric epithelial cells (AGS cells) and FACS quantification of adhering bacteria.

Key findings

Evaluation of time- and concentration-dependent incubation experiments indicated a significant decrease in l-dopa concentrations when coming into contact with H. pylori. The reduction in l-dopa concentrations was determined as 47 to 12%, referred to the initial starting concentration, with time-dependency and dependency of the H. pylori density. FITC-labelled H. pylori, pre-incubated with differing l-dopa concentrations, were shown to have a significantly reduced bacterial adhesion to AGS cells, with a maximum reduction of 22 ± 9%. These results demonstrate a direct interaction of l-dopa with the outer membrane proteins of H. pylori responsible for the adhesion to gastric epithelial cells. By this interaction the unbound l-dopa concentration in bacterial suspension was strongly reduced.

Conclusions

This study suggests a potential in-vitro interaction of l-dopa with H. pylori adhesins, confirming the clinical changes found in pharmacokinetics of l-dopa therapy by H. pylori-positive patients with Parkinson's disease.