The thick mucus layer of the gut provides a barrier to infiltration of the underlying epithelia by both the normal microbiota and enteric pathogens. Some members of the microbiota utilise mucin ...glycoproteins as a nutrient source, but a detailed understanding of the mechanisms used to breakdown these complex macromolecules is lacking. Here we describe the discovery and characterisation of endo-acting enzymes from prominent mucin-degrading bacteria that target the polyLacNAc structures within oligosaccharide side chains of both animal and human mucins. These O-glycanases are part of the large and diverse glycoside hydrolase 16 (GH16) family and are often lipoproteins, indicating that they are surface located and thus likely involved in the initial step in mucin breakdown. These data provide a significant advance in our knowledge of the mechanism of mucin breakdown by the normal microbiota. Furthermore, we also demonstrate the potential use of these enzymes as tools to explore changes in O-glycan structure in a number of intestinal disease states.
Intravenous fluids, an essential component of sepsis resuscitation, may paradoxically worsen outcomes by exacerbating endothelial injury. Preclinical models suggest that fluid resuscitation degrades ...the endothelial glycocalyx, a heparan sulfate-enriched structure necessary for vascular homeostasis. We hypothesized that endothelial glycocalyx degradation is associated with the volume of intravenous fluids administered during early sepsis resuscitation.
We used mass spectrometry to measure plasma heparan sulfate (a highly sensitive and specific index of systemic endothelial glycocalyx degradation) after 6 h of intravenous fluids in 56 septic shock patients, at presentation and after 24 h of intravenous fluids in 100 sepsis patients, and in two groups of non-infected patients. We compared plasma heparan sulfate concentrations between sepsis and non-sepsis patients, as well as between sepsis survivors and sepsis non-survivors. We used multivariable linear regression to model the association between volume of intravenous fluids and changes in plasma heparan sulfate.
Consistent with previous studies, median plasma heparan sulfate was elevated in septic shock patients (118 IQR, 113-341 ng/ml 6 h after presentation) compared to non-infected controls (61 45-79 ng/ml), as well as in a second cohort of sepsis patients (283 155-584 ng/ml) at emergency department presentation) compared to controls (177 144-262 ng/ml). In the larger sepsis cohort, heparan sulfate predicted in-hospital mortality. In both cohorts, multivariable linear regression adjusting for age and severity of illness demonstrated a significant association between volume of intravenous fluids administered during resuscitation and plasma heparan sulfate. In the second cohort, independent of disease severity and age, each 1 l of intravenous fluids administered was associated with a 200 ng/ml increase in circulating heparan sulfate (p = 0.006) at 24 h after enrollment.
Glycocalyx degradation occurs in sepsis and septic shock and is associated with in-hospital mortality. The volume of intravenous fluids administered during sepsis resuscitation is independently associated with the degree of glycocalyx degradation. These findings suggest a potential mechanism by which intravenous fluid resuscitation strategies may induce iatrogenic endothelial injury.
Septic patients frequently develop cognitive impairment that persists beyond hospital discharge. The impact of sepsis on electrophysiological and molecular determinants of learning is underexplored. ...We observed that mice that survived sepsis or endotoxemia experienced loss of hippocampal long-term potentiation (LTP), a brain-derived neurotrophic factor-mediated (BDNF-mediated) process responsible for spatial memory formation. Memory impairment occurred despite preserved hippocampal BDNF content and could be reversed by stimulation of BDNF signaling, suggesting the presence of a local BDNF inhibitor. Sepsis is associated with degradation of the endothelial glycocalyx, releasing heparan sulfate fragments (of sufficient size and sulfation to bind BDNF) into the circulation. Heparan sulfate fragments penetrated the hippocampal blood-brain barrier during sepsis and inhibited BDNF-mediated LTP. Glycoarray approaches demonstrated that the avidity of heparan sulfate for BDNF increased with sulfation at the 2-O position of iduronic acid and the N position of glucosamine. Circulating heparan sulfate in endotoxemic mice and septic humans was enriched in 2-O- and N-sulfated disaccharides; furthermore, the presence of these sulfation patterns in the plasma of septic patients at intensive care unit (ICU) admission predicted persistent cognitive impairment 14 days after ICU discharge or at hospital discharge. Our findings indicate that circulating 2-O- and N-sulfated heparan sulfate fragments contribute to septic cognitive impairment.
Pectic substances, one of the cell wall polysaccharides, exist widespread in vegetables and fruits. A surge of recent research has revealed that pectic substances can inhibit gut inflammation and ...relieve inflammatory bowel disease symptoms. However, physiological functions of pectins are strongly structure dependent. Pectic substances are essentially heteropolysaccharides composed of homogalacturonan and rhamnogalacturonan backbones substituted by various neutral sugar sidechains. Subtle changes in the architecture of pectic substances may remarkably influence the nutritional function of gut microbiota and the host homeostasis of immune system. In this context, developing a structure–function understanding of how pectic substances have an impact on an inflammatory bowel is of primary importance for diet therapy and new drugs. Therefore, the present review has summarized the polycomponent nature of pectic substances, the activities of different pectic polymers, the effects of molecular characteristics and the underlying mechanisms of pectic substances. The immunomodulated property of pectic substances depends on not only the chemical composition but also the physical structure characteristics, such as molecular weight (Mw) and chain conformation. The potential mechanisms by which pectic substances exert their protective effects are mainly reversing the disordered gut microbiota, regulating immune cells, enhancing barrier function, and inhibiting pathogen adhesion. The manipulation of pectic substances on gut health is sophisticated, and the link between structural specificity of pectins and selective regulation needs further exploration.
There is strong recent interest in ultrathin, flexible, safe energy storage devices to meet the various design and power needs of modern gadgets. To build such fully flexible and robust ...electrochemical devices, multiple components with specific electrochemical and interfacial properties need to be integrated into single units. Here we show that these basic components, the electrode, separator, and electrolyte, can all be integrated into single contiguous nanocomposite units that can serve as building blocks for a variety of thin mechanically flexible energy storage devices. Nanoporous cellulose paper embedded with aligned carbon nanotube electrode and electrolyte constitutes the basic unit. The units are used to build various flexible supercapacitor, battery, hybrid, and dual-storage battery-in-supercapacitor devices. The thin freestanding nanocomposite paper devices offer complete mechanical flexibility during operation. The supercapacitors operate with electrolytes including aqueous solvents, room temperature ionic liquids, and bioelectrolytes and over record temperature ranges. These easy-to-assemble integrated nanocomposite energy-storage systems could provide unprecedented design ingenuity for a variety of devices operating over a wide range of temperature and environmental conditions.
Low molecular heparins (LMWHs) are structurally complex, heterogeneous, polydisperse, and highly negatively charged mixtures of polysaccharides. The direct characterization of LMWH is a major ...challenge for currently available analytical technologies. Electrospray ionization (ESI) liquid chromatography-mass spectrometry (LC-MS) is a powerful tool for the characterization complex biological samples in the fields of proteomics, metabolomics, and glycomics. LC-MS has been applied to the analysis of heparin oligosaccharides, separated by size exclusion, reversed phase ion-pairing chromatography, and chip-based amide hydrophilic interaction chromatography (HILIC). However, there have been limited applications of ESI-LC-MS for the direct characterization of intact LMWHs (top-down analysis) due to their structural complexity, low ionization efficiency, and sulfate loss. Here we present a simple and reliable HILIC-Fourier transform (FT)-ESI-MS platform to characterize and compare two currently marketed LMWH products using the top-down approach requiring no special sample preparation steps. This HILIC system relies on cross-linked diol rather than amide chemistry, affording highly resolved chromatographic separations using a relatively high percentage of acetonitrile in the mobile phase, resulting in stable and high efficiency ionization. Bioinformatics software (GlycReSoft 1.0) was used to automatically assign structures within 5-ppm mass accuracy.
Dibutyl phthalate (DBP) is an environmental pollutant that can threaten human health. The strain Arthrobacter sp. ZJUTW, isolated from the sludge of a river of Hangzhou, can efficiently degrade DBP. ...Its genomic and transcriptomic differences when cultivated with DBP compared with glucose revealed specific DBP metabolic pathways in the ZJUTW strain. The degrading gene clusters localize separately on a circular chromosome and a plasmid pQL1. Genes related to the initial steps of DBP degradation from DBP to phthalic acid (PA), the pehA gene, and pht gene cluster, are located on the plasmid pQL1. However, the pca gene cluster related to the transforming of intermediate protocatechuic acid (PCA) to acetyl‐CoA, is located on the chromosome. After comparative analysis with the reported gene clusters, we found that there were a series of homologous genes in pht and pca gene clusters that contribute to the efficient degradation of DBP by ZJUTW. In addition, transcriptomic analysis suggested a synergistic effect between pht and pca clusters, which also favor ZJUTW allowing it to efficiently degrade DBP. Combined genomic and transcriptomic analyses revealed a complete DBP metabolic pathway in Arthrobacter sp. ZJUTW that is different from that of other reported Arthrobacter strains. After necessary modification based on its metabolic characteristics, Arthrobacter sp. ZJUTW or its derivatives might represent promising candidates for the bioremediation of DBP pollution.
DBP degrading strain Arthrobacter sp. ZJUTW contains a new complete metabolic pathway from DBP to Acetyl‐CoA first found in genus Arthrobacter.
Hyaluronic acid (HA) is a major glycosaminoglycan, a family of structurally complex, linear, anionic hetero-co-polysaccharides. HA is important in various anatomical structures including the eyes, ...joints, heart and myriad intricate tissues, and is currently widely used in the therapeutics and cosmetics areas. The synthesis of HA of well-defined and uniform chain lengths is of major interest for the development of safer and more reliable drugs and to gain a better understanding of its structure-activity relationships. However, HA has received less attention from the synthetic carbohydrate community compared with other members of the glycosaminoglycan family. In this review, we examine the remarkable progress that has been made in the chemical and chemoenzymatic synthesis of HA, providing a broad spectrum of options to access HA of well controlled chain lengths.
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•A brief overview of CBD development in recent decades is presented.•Approaches for accessing specific carbohydrates and glycoconjugates are clarified.•Microarray and library are ...critical for rapid screening of bioactive carbohydrates.•Gut microbiota system is promising for evaluation of orally administrated CBD.•Advanced technologies and toolkit accelerated the CBD discovery.
Carbohydrates, one of the most abundant and widespread biomolecules in nature, play indispensable roles in diverse biological functions, and represent a treasure trove of untapped potential for pharmaceutical applications. Here, we provide a brief overview of carbohydrate-based drug development (CBDD) over the past two decades. More importantly, advanced techniques and methodologies related to CBDD are emerging, including enzymatic synthesis, metabolic engineering, site-specific glycoconjugation, carbohydrate libraries and microarrays as well as carbohydrate-gut microbiome evaluation. These technologies have dramatically accelerated the speed of CBDD. The recently approved drugs and emerging techniques summarized herein will inspire new sights into potential opportunities to discover novel carbohydrate drugs.
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