Sialic Acid Content Research Articles

Hydrogel Grating Sensors with Boron Affinity and Molecular Imprinting Effects for Rapid and Sensitive Detection of Tumor Marker Sialic Acid.

Rapid and sensitive detection of the concentration of sialic acid (SA) in serum is crucial for early tumor screening and prognostic assessment; however, it still remains challenging. Here, we propose a novel kind of hydrogel grating sensor with boron affinity and molecular imprinting effects (B-MIP) for the rapid and sensitive detection of SA concentration in serum. The hydrogel gratings feature uniform surface relief microstructures and incorporate highly specific recognition binding sites into SA molecules provided by boron affinity and molecular imprinting. The periodic nanoridges of hydrogel gratings increase the specific surface area contacting the environmental solution; therefore, fast detection can be achieved within 2 min. Upon recognition of SA molecules, the height of hydrogel gratings changes at the nanoscale, causing a change in the diffraction efficiency of the hydrogel gratings. The B-MIP hydrogel grating sensors have highly specific binding sites to SA molecules distributed throughout the whole hydrogel and can preferentially and selectively recognize and respond to the SA molecules even in the presence of interference substances glucose and fructose with high concentrations. The B-MIP hydrogel grating sensors are effectively applicable for the rapid and sensitive detection of SA concentrations in real serum samples with satisfactory accuracy and precision. Our approach provides an excellent strategy to address the current challenges in SA detection and provides new insights into the detection of tumor markers in serum, thereby opening up new ways to accurately detect complex biological samples in analytical science.

Calculation of continuous reference intervals for biological parameters exhibiting strong age‐dependent level changes: Its application to glycosaminoglycans and sialic acid in urine

AbstractGlycosaminoglycan (GAG) and sialic acid (total and free) assays are used as first‐line screening tests for the diagnosis of mucopolysaccharidoses and glycoproteinoses, respectively. There is a pronounced age‐dependent variation in the urinary concentrations of these metabolites in the normal population, and the stratification of the reference values into discrete age ranges may lead to an undesirably high number of false‐positive or false‐negative results. The aim of this study was to design a method for calculating continuous reference intervals as a function of age and its application to the analysis of GAGs and sialic acid (total, free, and conjugated) in urine. In the postpubertal period, concentrations of urinary GAGs and sialic acid have reached a plateau, so a traditional calculation of the reference range in this specific age group was considered appropriate. In the prepubertal period, a nonlinear regression performed with the Excel add‐in Solver was used to fit the logarithmized concentrations of the controls to a curve that represents the mean values as a function of age. A uniform distribution of the residuals was obtained, which allowed the calculation of the reference intervals by adding the values of their 2.5 and 97.5 percentiles to the independent variable of the regression curve to calculate the upper and lower reference curves. The main advantages of the developed method are (1) a reduction in the number of control samples needed to obtain adequate reference intervals and (2) an improvement in the reliability of diagnostic screening by reducing the uncertainty generated by the gaps in the traditional age‐stratified method.

Association between sialic acid, sialidase activity and cholesterol of lipid-containing circulating immune complexes in the blood serum of patients with atherosclerosis

Atherosclerosis is the most common chronic non-infectious diseases, in the pathogenesis of which the accumulation of lipids in the subendothelial layer of the arteries and the local inflammatory reaction play a significant role. The source of lipid accumulation in the vascular wall is modified low-density lipoproteins. Desialylation is one of the known modifications that leads to the emergence of atherogenic properties in low-density lipoproteins. Enzymes that have sialidase activity circulate in human blood, i.e., the ability to cleave sialic acid from low-density lipoproteins. Desialylated low-density lipoproteins are autoantigens and induce the production of IgG autoantibodies, which form immune complexes with low-density lipoproteins, which aggravates the course of atherosclerosis. The purpose of the study was to establish associations between the levels of sialic acid in low-density lipoproteins, sialidase activity and the cholesterol content of lipid-containing circulating immune complexes in the blood serum of patients with atherosclerosis. Blood sera from patients with coronary heart disease were used as biological material to determine indicators of sialidase activity, cholesterol content of lipid-containing circulating immune complexes and sialic acid in low-density lipoproteins, which were isolated from blood serum. Serum samples were obtained from the laboratory of clinical biochemistry of the Institute of Clinical Cardiology, A.L. Myasnikov Federal State Budgetary Institution National Medical Research Center of Cardiology named after Academician E.I. Chazov as unutilized residues after performing routine biochemical tests. Fifty-one samples of blood serum and low-density lipoproteins isolated from it were analyzed. A significant positive relationship was revealed between the cholesterol content of circulating immune complexes and sialidase activity in the blood serum (r = 0.305 at p = 0.029). At the same time, no correlation was found between the content of sialic acid in low-density lipoproteins and sialidase activity in the blood serum, as well as between the cholesterol content of circulating immune complexes in the blood serum and sialic acid in low-density lipoproteins. It should be assumed that increased sialidase activity in the blood serum leads to the formation of desialylated immunogenic low-density lipoproteins with the subsequent appearance of autoantibodies and the formation of lipid-containing circulating immune complexes.

Ganoderma lucidum extract normalizes the concentration of sialic acids in erythrocytes and blood plasma of rats with experimental metabolic syndrome

Ganoderma lucidum extract normalizes the concentration of sialic acids in erythrocytes and blood plasma of rats with experimental metabolic syndrome

Soft X-ray spectromicroscopy of human fibroblasts with impaired sialin function.

Salla disease (SD) is a lysosomal storage disease where free sialic acid (SA) accumulates in lysosomes due to the impaired function of a membrane protein, sialin. Synchrotron radiation-based scanning transmission soft X-ray spectromicroscopy (STXM) was used to analyze both SD patients' fibroblasts and normal human dermal fibroblasts (NHDF) from healthy controls. Both cell lines were also cultured with N-acetyl-d-mannosamine monohydrate (ManNAc) to see if it increased SA concentration in the cells. The STXM technique was chosen to simultaneously observe the morphological and chemical changes in cells. It was observed that free SA did not remain in the lysosomes during the sample processing, leaving empty vacuoles to the fibroblasts. The total cytosol and entire cell spectra, however, showed systematic differences between the SD and NHDF samples, indicating changes in the relative macromolecular concentrations of the cells. The NHDF cell lines contained a higher relative protein concentration compared to the SD cell lines, and the addition of ManNAc increased the relative protein concentration in both cell lines. In this study, two sample preparation methods were compared, resin-embedded thin sections and cells grown directly on sample analysis grids. While the samples grown on the grids exhibited clean, well-resolved spectra not masked by embedding resin, the low penetration depth of soft X-rays hindered the analysis to only the thin region of the microfilaments away from the thick nucleus.

Induced Muscle and Liver Absence of Gne in Postnatal Mice Does Not Result in Structural or Functional Muscle Impairment.

GNE Myopathy is a unique recessive neuromuscular disorder characterized by adult-onset, slowly progressive distal and proximal muscle weakness, caused by mutations in the GNE gene which is a key enzyme in the biosynthesis of sialic acid. To date, the precise pathophysiology of the disease is not well understood and no reliable animal model is available. Gne KO is embryonically lethal in mice. To gain insights into GNE function in muscle, we have generated an inducible muscle Gne KO mouse. To minimize the contribution of the liver to the availability of sialic acid to muscle via the serum, we have also induced combined Gne KO in liver and muscle. A mouse carrying loxp sequences flanking Gne exon3 was generated by Crispr/Cas9 and bred with a human skeletal actin (HSA) promoter driven CreERT mouse. Gne muscle knock out was induced by tamoxifen injection of the resulting homozygote GneloxpEx3loxp/HSA Cre mouse. Liver Gne KO was induced by systemic injection of AAV8 vectors carrying the Cre gene driven by the hepatic specific promoter of the thyroxine binding globulin gene. Characterization of these mice for a 12 months period showed no significant changes in their general behaviour, motor performance, muscle mass and structure in spite of a dramatic reduction in sialic acid content in both muscle and liver. We conclude that post weaning lack of Gne and sialic acid in muscle and liver have no pathologic effect in adult mice. These findings could reflect a strong interspecies versatility, but also raise questions about the loss of function hypothesis in Gne Myopathy. If these findings apply to humans they have a major impact on therapeutic strategies.

Surface Sialic Acid Detection of Small Extracellular Vesicles at the Single-Particle Level by Nano-Flow Cytometry.

Glycans, particularly sialic acids (SAs), play crucial roles in diverse biological processes. Despite their significance, analyzing specific glycans, such as sialic acids, on individual small extracellular vesicles (sEVs) has remained challenging due to the limited glycan capacity and substantial heterogeneity of sEVs. To tackle this issue, we introduce a chemical modification method of surface SAs on sEVs named PALEV-nFCM, which involves periodate oxidation and aniline-catalyzed oxime ligation (PAL), in conjunction with single-particle analysis using a laboratory-built nano-flow cytometer (nFCM). The specificity of the PALEV labeling method was validated using SA-decorated liposomes, enzymatic removal of terminal SA residues, lectin preblocking, and cellular treatment with an endogenous sialyltransferase inhibitor. Comprehensive mapping of SA distributions was conducted for sEVs derived from different sources, including conditioned cell culture medium (CCCM) of various cell lines, human saliva, and human red blood cells (RBCs). Notably, treatment with the calcium ionophore substantially increases the population of SA-positive RBC sEVs and enhances the SA content on individual RBC sEVs as well. nFCM provides a sensitive and versatile platform for mapping SAs of individual sEVs, which could significantly contribute to resolving the heterogeneity of sEVs and advancing the understanding of their glycosignature.

Sialyllactose supplementation enhances sialylation of Fc-fusion glycoprotein in recombinant Chinese hamster ovary cell culture

Sialylation during N-glycosylation plays an important role in the half-life of therapeutic glycoproteins in vivo and has sparked interest in the production of therapeutic proteins using recombinant Chinese hamster ovary (rCHO) cells. To improve the sialylation of therapeutic proteins, we examined the effect of sialyllactose supplementation on sialylation of Fc-fusion glycoproteins produced in rCHO cells. Two enzymatically-synthesized sialyllactoses, 3′-sialyllactose (3′-SL) and 6′-sialyllactose (6′-SL), were administered separately to two rCHO cell lines producing the same Fc-fusion glycoprotein derived from DUKX-B11 and DG44, respectively. Two sialyllactoses successfully increased sialylation of Fc-fusion glycoprotein in both cell lines, as evidenced by isoform distribution, sialylated N-glycan formation, and sialic acid content. Increased sialylation by adding sialyllactose was likely the result of increased amount of intracellular CMP-sialic acid (CMP-SA), the direct nucleotide sugar for sialylation. Furthermore, the degree of sialylation enhanced by sialyllactoses was slightly effective or nearly similar compared with the addition of N-acetylmannosamine (ManNAc), a representative nucleotide sugar precursor, to increase sialylation of glycoproteins. The effectiveness of sialyllactose was also confirmed using three commercially available CHO cell culture media. Taken together, these results suggest that enzymatically-synthesized sialyllactose represents a promising candidate for culture media supplementation to increase sialylation of glycoproteins in rCHO cell culture.

Sialylation status in placentas from anti-Ro/SSA- and anti-La/SSB-positive pregnant women

Women affected by different autoimmune diseases and displaying positivity for anti-Ro/SSA and anti-La/SSB autoantibodies are at high risk of adverse pregnancies in which placental dysfunction seems to play a determinant role. Sialylation is known to have important implications in the maintenance of the normal morpho-functional features of the placenta. Hence, the present study aimed to investigate possible changes in the distribution and content of sialic acids (Sias) with different glycosidic linkages (i.e., α2,3 and α2,6 Galactose- or N-acetyl-Galactosamine-linked Sias, and polysialic acid) in placentas from anti-Ro/SSA- and anti-La/SSB-positive pregnant women with autoimmune diseases by using lectin histochemistry and polysialic acid immunohistochemistry. Our findings revealed lower levels of α2,3-linked Sias in the trophoblast and basement membrane and/or basal plasma membrane of the pathological cases respect to control placentas. Some vessels of the pathological cases displayed α2,3-linked Sias. α2,6-linked Sias positivity was detected in the trophoblast and in some vessels of the pathological cases, while in control samples it was present only in the vessels. Lower levels of polysialic acid were observed in the trophoblast of pathological cases compared to controls. Collectively, our findings suggest that multiple changes in the sialylation status of placenta might affect placental morpho-functional features in anti-Ro/SSA- and anti-La/SSB-positive pregnancies.

Rapid total sialic acid monitoring during cell culture process using a machine learning model based soft sensor.

Total sialic acid content (TSA) in biotherapeutic proteins is often a critical quality attribute as it impacts the drug efficacy. Traditional wet chemical assays to quantify TSA in biotherapeutic proteins during cell culture typically takes several hours or longer due to the complexity of the assay which involves isolation of sialic acid from the protein of interest, followed by sample preparation and chromatographic based separation for analysis. Here, we developed a machine learning model-based technology to rapidly predict TSA during cell culture by using typically measured process parameters. The technology features a user interface, where the users only have to upload cell culture process parameters as input variables and TSA values are instantly displayed on a dashboard platform based on the model predictions. In this study, multiple machine learning algorithms were assessed on our dataset, with the Random Forest model being identified as the most promising model. Feature importance analysis from the Random Forest model revealed that attributes like viable cell density (VCD), glutamate, ammonium, phosphate, and basal medium type are critical for predictions. Notably, while the model demonstrated strong predictability by Day 14 of observation, challenges remain in forecasting TSA values at the edges of the calibration range. This research not only emphasizes the transformative power of machine learning and soft sensors in bioprocessing but also introduces a rapid and efficient tool for sialic acid prediction, signaling significant advancements in bioprocessing. Future endeavors may focus on data augmentation to further enhance model precision and exploration of process control capabilities.

Extraction optimization, partial purification, and characterization of sialoglycoproteins from Labeo rohita roes

In India, fish roes are generally considered worthless garbage and disposed of without recovering the valuable molecules, creating environmental and disposal problems. The present investigation aimed to optimize the extraction conditions, partial purification, and characterization of sialoglycoproteins (RRSGP) from Labeo rohita (rohu) roes. RSM generated optimum conditions for maximum RRSGP (70.49 %) extraction, which were 1.25 M NaCl, 1:32.5(w/v) solid-to-liquid ratio, 47.5 °C temperature, and 3 h time. Further, sialoglycoproteins from RRSGPs were partially purified, and result revealed that obtained peak-1 (PRRSGP) using QFF anion exchange chromatography exhibited higher glycoprotein and sialic acid content (p < 0.05). SDS-PAGE pattern of PRRSGP presented dominant bands of 97 kDa and 27 kDa glycoproteins. FTIR spectrum of PRRSGP confirmed the presence of glycated proteins. HPLC analysis revealed that PRRSGP consists of Neu5Ac. Furthermore, β-elimination reaction elucidated that PRRSGP contained N-glycosidic linkage. PRRSGP exhibited tyrosine and glutamate as primary amino acids. Glycan part of PRRSGP presented mannose and N-acetyl galactosamine as dominant neutral and amino sugar, respectively. Furthermore, PRRSGP exhibited antioxidant activity with EC50 value for DPPH (8.79 mg/ml) and ABTS (2.21 mg/ml). Besides, RRSGP displayed better protein solubility, foaming, and emulsion properties. Therefore, rohu roes are potential source of sialoglycoproteins that can be recovered and used as bio-functional ingredients in food and nutraceutical applications.

HPLC-QQQ-MS/MS-based authentication and determination of free and bound sialic acids content in human, bovine, sheep, goat milk, and infant formula.

An accurate method for qualitative and quantitative analysis of lipid-bound (LB), protein-bound (PB), oligosaccharides-bound, and free sialic acids in milk was developed by using high-performance liquid chromatography -triple quadrupole-tandem mass spectrometer. The profile of free and bound sialic acids in milk (human, bovine, goat, and sheep) and infant formula (IF) was examined in the present study. Human milk contains only N-acetylneuraminic acid (Neu5Ac) and was mainly present in the form of oligosaccharide-bound. The content of total Neu5Ac (T-Neu5Ac), free and bound Neu5Ac in human milk decreased with the prolongation of lactation. The most intriguing finding was the increase in the proportion of PB and LB sialic acids. The sialic acids in bovine and sheep milk were mainly PB and oligosaccharides-bound Neu5Ac. T-Neu5Ac in goat milk (GM) was 67.44-89.72µg/mL and was mainly PB Neu5Ac, but total N-glycolylneuraminic acid (T-Neu5Gc) content of GM can be as high as 100.01µg/mL. The concentration of T-Neu5Gc in sheep and GM was significantly higher than that of bovine milk (BM). T-Neu5Gc content of GM -based IF was 264.86µg/g, whereas T-Neu5Gc content of BM -based IF was less (2.26-17.01µg/g). Additionally, our results found that there were also sialic acids in IF ingredients, which were mainly bound with protein and oligosaccharides, primarily derived from desalted whey powder and whey protein concentrate.

Development of a biotechnology process for the production of a novel hyperglycosylated long-acting recombinant bovine follicle-stimulating hormone.

Follicle-stimulating hormone (FSH) is an important protein used for bovine ovarian hyperstimulation in multiple ovulation and embryo transfer technology (MOET). Several attempts to produce bovine FSH (bFSH) in recombinant systems have been reported, nonetheless, up to date, the most commonly used products are partially purified preparations derived from porcine or ovine (pFSH or oFSH) pituitaries. Here we describe the development of a biotechnology process to produce a novel, hyperglycosylated, long-acting recombinant bFSH (LA-rbFSH) by fusing copies of a highly O-glycosylated peptide. LA-rbFSH and a nonmodified version (rbFSH) were produced in suspension CHO cell cultures and purified by IMAC with high purity levels (>99%). LA-rbFSH presented a higher glycosylation degree and sialic acid content than rbFSH. It also demonstrated a notable improvement in pharmacokinetic properties after administration to rats, including a higher concentration in plasma and a significant (seven-fold) reduction in apparent clearance (CLapp). In addition, the in vivo specific bioactivity of LA-rbFSH in rats was 2.4-fold higher compared to rbFSH. These results postulate this new molecule as an attractive substitute for commercially available porcine pituitary-derived products.

Association of Plasma Sialic Acid concentrations with Diabetic Nephropathy in Syrian Individuals with Type 2 Diabetes Mellitus

Association of Plasma Sialic Acid concentrations with Diabetic Nephropathy in Syrian Individuals with Type 2 Diabetes Mellitus

#1669 Gangliosides as biomarkers for early diagnosis of diabetic kidney disease: detection and characterization by high-performance mass spectrometry

Abstract Background and Aims The early identification of diabetic kidney disease (DKD) is crucial as it may facilitate immediate intervention, thus impeding the progression of the condition and the risk of developing end-stage renal disease (ESRD). Enhancing our understanding of the pathophysiology of this microvascular complication as well as developing therapeutic strategies are imperative. Hence, the aim of the current study was to address the problematics of detection and characterization of gangliosides in the urine of type 2 diabetes mellitus (DM) patients with DKD. Method In this cross-sectional study, the urine ganglioside content from 24 h collected urine samples of 60 type 2 DM patients (20 with normal to mildly increased albuminuria—A1 group, 20 with moderately increased albuminuria—A2 group, 20 with severe increased albuminuria—A3 group) was compared to that of 20 healthy controls using a promising technique based on high-resolution (HR) mass spectrometry (MS). Furthermore, for structural elucidation of individual compounds, we isolated the ions GT1 (d18:1/18:0), identified at m/z 708.3379 and, GQ1 (d18:1/18:0) at m/z 812.7068, observed only in the screening analysis of A3 patients, and exposed them to Higher-energy collisional dissociation (HCD MS/MS) in the negative ion mode. Results Patients with type 2 diabetes mellitus display a considerably greater abundance of different species in their urinary gangliosidome, which varies in either glycan or ceramide structure, in comparison to the control group. Even within the A1 group, a greater variety of structures exhibiting varying degrees of sialylation were observed. A wide range of carbohydrate chains were discovered, ranging from short, monosialylated chains (GM) to complex, pentasialylated chains (GP). Additionally, some ganglioside chains were modified with and O-acetyl (O-Ac) attachments. The gangliosidome of the A3 group comprises a higher variety of structures, compared to A1 and A2, differing in their overall sialic acid content, and more complex structures, including various biologically significant modifications, such as O-fucosylation, O-GalNAc and CH3COO− attachments. Both albuminuria and glomerular filtration rate proved to be correlated with the degree of sialylation of species. Furthermore, significant alterations occur also in the ceramide part, with the most noteworthy being the presence of sphingoid base trihydroxylation, which is shown in both A1 and A3 samples. Additionally, A3 exhibits unusual length of the fatty acid chains. GQ1d(d18:1/18:0), GT1α(d18:1/18:0), and GT1b(d18:1/18:0) were identified as predictive for specific isomers linked to the location of Neu5Ac along the oligosaccharide structure using HCD-based MS/MS. Conclusion We concluded that gangliosides may be involved in the development and progression of DKD through the use of mass spectrometry techniques, which provides considerable precision and ultrahigh reproducibility, sensitivity and processing power, and the capability to identify minor elements in complex biological matrices. Thus, a set of promising bioindicators for early detection and progression of DKD was established. Even in the normoalbuminuric stage, the sialylation level of the expressed species appears to be an extremely important biochemical marker of DKD. Moreover, the modifications detected in the composition of ceramide indicate that, alongside the oligosaccharide structure, the lipid component might function as a specific molecular indicator for different stages of DKD. The presence of a few isomers in the A3 group has been discovered to be associated with DKD progression, based on the informative sequence ions obtained from the structural analysis. Moreover, gangliosides might be used as target molecules for the implementation of therapeutic schemes in type 2 DM patients.

ROLE OF NF-κB TRANSCRIPTION FACTOR ACTIVATION IN THE PROCESSES OF CONNECTIVE TISSUE COMPONENTS DEGRADATION IN SKELETAL MUSCLES UNDER METABOLIC SYNDROME

Connective tissue, encompassing both cellular and non-cellular elements, plays an important role in the progression of numerous pathological processes across various organs and tissues. Within skeletal muscle tissue, the extracellular matrix not only plays a structural and supporting function, but it is a complex multicomponent system that performs a number of regulatory functions. At present, the effect of activation of the transcription factor NF-κB on the quantitative and qualitative composition of the components of the extracellular matrix in skeletal muscles under metabolic syndrome development is insufficiently studied. The aim of this work is to study the effect of ammonium pyrrolidinedithiocarbamate on the concentration of glycosaminoglycans, the concentration of individual fractions of glycosaminoglycans, the content of free L-oxyproline and sialic acids in the biceps femoris muscle of rats under metabolic syndrome. The study was conducted on 24 male Wistar rats weighing 200-260 g, which were randomly divided into 4 groups of 6 animals each. The first was control; the second made up the metabolic syndrome modeling group. Metabolic syndrome was reproduced by adding a 20% fructose solution to the standard vivarium diet as the only source of drinking water. Metabolic syndrome was modelled for 60 days. The third group received ammonium pyrrolidinedithiocarbamate administration at a dose of 76 mg/kg intraperitoneally (i/p) three times a week for 60 days. The fourth group underwent combined treatment involving the administration of both ammonium pyrrolidinedithiocarbamate and metabolic syndrome modeling. In a 10% homogenate of the biceps femoris muscle, the total concentration of glycosaminoglycans, the concentration of the heparin-heparan fraction of glycosaminoglycans, the keratan-dermatan fraction of glycosaminoglycans, the chondroitin fraction of glycosaminoglycans, and the content of free L-oxyproline and sialic acids were assessed. The introduction of ammonium pyrrolidinedithiocarbamate under metabolic syndrome modelling led to a decrease in the total concentration of glycosaminoglycans by 9.2% compared to the metabolic syndrome group. Under these conditions, the concentration of the heparin-heparan fraction increased by 121.1%, the keratan-dermatan fraction decreased by 32.8%, and the concentration of the chondroitin fraction decreased by 38.7% compared to the metabolic syndrome group. The concentration of free L-oxyproline and sialic acids in the biceps femoris muscle decreased by 19.8% and 24.4%, respectively, compared to the metabolic syndrome group. Blockade of activation of the transcription factor NF-κB by intraperitoneal administration of ammonium pyrrolidinedithiocarbamate against the background of metabolic syndrome modelling leads to a decrease in the depolymerization of glycoproteins and proteoglycans, reduces the intensity of collagenolysis and leads to a redistribution of concentrations of individual fractions of glycosaminoglycans, characterized by an increase in the content of the heparin-heparan fraction and a decrease in chondroitin and keratan-dermatan fractions in the biceps femoris muscle of rats.

Role of neuraminidase in promoting the shedding of endothelial mechanosensing structures in type 2 diabetes

Endothelial dysfunction represents a causal factor in the pathogenesis of cardiovascular disease associated with type 2 diabetes (T2D). Previous work shows that endothelial mechanosensing structures are degraded in T2D, resulting in impaired shear stress mechanotransduction and decreased endothelial-derived nitic oxide (NO) bioavailability. Recent evidence suggests that glypican-1, a well-known mechanosensor, is a substrate of the proinflammatory enzyme a disintegrin and metalloproteinase-17 (ADAM17). A key step in ADAM17 activation is externalization of phosphatidylserine (PS) to the outer leaflet of the plasma membrane, which can be mediated by the phospholipid scramblase anoctamin-6 (ANO6). However, whether ANO6-mediated activation of ADAM17 leads to glypican-1 shedding in endothelial cells remains unknown. Also unknown are the mechanisms by which this pathway becomes overactive in T2D. We recently reported that T2D is associated with increased circulating levels of neuraminidase, a soluble enzyme that cleaves sialic acid residues. We also showed that intraluminal exposure of isolated arteries to neuraminidase impairs shear stress mechanotransduction. Herein, we tested the hypothesis that neuraminidase-induced impaired shear stress mechanotransduction is mediated by ANO6-induced ADAM17 activation and consequent shedding of glypican-1. All reported differences are significant at P&lt;0.05. In support of our hypothesis, we show that neuraminidase and ADAM17 activities are increased, while nitrite (NO surrogate) is decreased, in plasma of men and women with T2D who also display evidence of impaired shear stress mechanotransduction ( i.e., diminished flow-mediated dilation). In cultured endothelial cells, we show that neuraminidase exposure decreases sialic acid content and increases intracellular Ca2+ mobilization, adhesion of lactadherin (a peptide that binds externalized PS), ADAM17 activity, and shedding of glypican-1. Also in cultured endothelial cells, overexpression of ADAM17 increases shedding of glypican-1 and impairs shear stress-induced activation of endothelial NO synthase. Congruently, intraluminal exposure of human omental arteries to active ADAM17 recombinant protein impairs flow-mediated dilation. Furthermore, silencing of ANO6 reduces ADAM17 activity, leading to increased presence of glypican-1 on the endothelial cell surface. Taken together, we provide evidence that neuraminidase, an enzyme increased in the circulation of individuals with T2D, promotes ANO6-dependent externalization of PS in endothelial cells, which in turn leads to ADAM17 activation and consequent shedding of glypican-1. Thus, this work supports the idea that the neuraminidase-ANO6-ADAM17 axis should be considered as a potential target for restoring endothelial mechanosensation and improving NO bioavailability in T2D. R01HL151384 (to LAML and JP), R01HL153264 (to LAML and JP), R01HL137769 (to JP), and R21DK116081 (to CM-A). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Employing fruit juices to hydrolyze edible bird's nest and enhance the antioxidant, anti-tyrosinase, and wound-healing activities of the hydrolysates

Enzymatic hydrolysis of edible bird's nest (EBN) has attracted great interest in both scientific and commercial fields due to the enhancement of solubility and nutraceutical values. The present study attempted to investigate the hydrolysis of EBN with papaya (Carica papaya L.), pineapple (Ananas comosus (L.) Merr.), and cantaloupe (Cucumis melo L.) juices as well as two commercial enzymes papain and bromelain. Our analysis revealed that EBN hydrolysis with pineapple juice and bromelain produced a degree of hydrolysis (DH) value of approximately 27 % while it was about 25 % for the hydrolysis with cantaloupe juice and 22 % for the hydrolysis with papaya juice and papain after 4 h of treatment. When EBN was digested by fruit juices and enzymes, the protein solubility and free sialic acid content were increased and the highest values were achieved for EBN hydrolysis with pineapple juice and bromelain (estimately 11 mg/mL of soluble protein and 18 g/kg of free sialic acid). The ABTS•+-scavenging, •OH-scavenging, and anti-tyrosinase capacities were higher in the EBN hydrolysates by papaya juice (IC50 of 0.034, 0.108, and 0.419 mg/mL, respectively), pineapple juice (IC50 of 0.025, 0.045, and 0.190 mg/mL, respectively), and cantaloupe juice (IC50 of 0.031 mg/mL, 0.056, and 0.339 mg/mL, respectively) than in the hydrolysates by unhydrolyzed EBN (IC50 of 0.094, 0.366, and 1.611 mg/mL, respectively). An improvement in ABTS•+-scavenging, •OH-scavenging, and anti-tyrosinase abilities was also observed for the hydrolysates by papain (IC50 of 0.041, 0.129, and 0.417 mg/mL, respectively) and bromelain (IC50 of 0.025, 0.069, and 0.336 mg/mL, respectively) but in a lesser extent as compared to the hydrolysates by respective papaya and pineapple juices. Noticeably, the EBN hydrolysates by fruit juices remarkably enhanced the wound closure in human fibroblasts by about 1.4–1.8 times after 24 h of treatment whereas this property was insignificant in the hydrolysates by enzymes. As papaya, pineapple, and cantaloupe juices are easily obtainable and have pleasant flavors, our results provide a possible method to hydrolyze EBN and apply the resultant hydrolysates in functional food products.

Potential effects of sialic acid and 3′-Sialyllactose on intestinal health and anti-cardiovascular disease in mice fed with a high-fat diet

This study investigated the beneficial effects of sialic acid (SA) and 3′-Sialyllactose (3′-SL) on the intestinal and cardiovascular health of mice fed with a high-fat diet. Male C57BL/6J mice were administered 0.9 % NaCl, SA, or 3′-SL by gavage throughout the experiment. After eight weeks, the ability of glucose regulation increased, the blood lipid decreased, the serum inflammatory factors decreased, and the SA content of low-density lipoprotein increased in the intervention groups. Transcriptome analysis of the small intestine and colon revealed gene expression patterns related to digestion, absorption, immunity, and the circadian rhythm. Metabonomic analysis of colon contents corroborated the findings of colonic transcriptomics.. The gut microbiome was characterised by an increase in beneficial bacteria and a decrease in harmful bacteria, which correlated with the blood lipid concentration. This study highlights the potential effects of SA and 3′-SL on intestinal health and anti-cardiovascular disease.

Influence of organism stimulation with bacterial lipopolysaccharide on the metabolism of the extracellular matrix of the heart of rats under conditions of experimental metabolic syndrome

Until recently, the extracellular matrix was considered only a structural component of the organ, which performs exclusively the function of the framework. However, recent studies provide insight into a much broader role of extracellular matrix in metabolic homeostasis, the transmission of intra-organ and tissue signals. Metabolic syndrome and chronic infectious diseases can change the extracellular matrix’s structure in the heart. However, the combined effect of bacterial lipopolysaccharide and metabolic syndrome on extracellular matrix of the heart remains insufficiently elucidated at present. The purpose of this work is to establish the effect of organism stimulation with bacterial lipopolysaccharide on the concentration of different fractions of glycosaminoglycans, the intensity of collagenolysis and the content of sialic acids in the heart of rats under conditions of experimental metabolic syndrome. The study was conducted on 24 sexually mature rats of the “Wistar” line weighing 200-260 g. Animals were divided into 4 groups with 6 animals in each group: control, metabolic syndrome group, lipopolysaccharide injection group and combination of lipopolysaccharide injection and metabolic syndrome group. Metabolic syndrome was modelled by using 20% fructose solution as the only water source. Lipopolysaccharide of S. typhi was administered according to the scheme: the first week, 0.4 μg/kg 3 times intraperitoneally, then once a week 0.4 μg/kg throughout the experiment. Experiment lasted for 60 days. The concentration of glycosaminoglycans, their separate fractions, the content of free L-hydroxyproline and sialic acids was studied in 10% rat heart homogenate. The combined effect of stimulation of the organism with bacterial lipopolysaccharide and metabolic syndrome modeling led to an increase in the total concentration of glycosaminoglycans in the heart of rats by 73.46% compared to the control group. Under these conditions, the concentration of the heparin-heparan fraction of glycosaminoglycans in the heart of rats increased by 188.64% compared to the control group. The content of the keratan-dermatan fraction of glycosaminoglycans increased by 75.34%, and the chondroitin fraction of glycosaminoglycans increased by 17.63%. The concentration of free L-hydroxyproline increased by 167.23%. The content of sialic acids increased by 66.95%. Metabolic syndrome, stimulation of the organism with bacterial lipopolysaccharide and their combination lead to intensification of degradation of the extracellular matrix of the heart of rats due to increased collagenolysis, destruction of proteoglycans and glycoproteins.