Lignin/Carbohydrate Complex Isolated from Posidonia oceanica Sea Balls (Egagropili): Characterization and Antioxidant Reinforcement of Protein-Based Films.

A lignin fraction (LF) was extracted from the sea balls of Posidonia oceanica (egagropili) and extensively dialyzed and characterized by FT-IR and NMR analyses. LF resulted water soluble and exhibited a brownish-to-black color with the highest absorbance in the range of 250-400 nm, attributed to the chromophore functional groups present in the phenylpropane-based polymer. LF high-performance size exclusion chromatography analysis showed a highly represented (98.77%) species of 34.75 kDa molecular weight with a polydispersity index of 1.10 and an intrinsic viscosity of 0.15. Quantitative analysis of carbohydrates indicated that they represented 28.3% of the dry weight of the untreated egagropili fibers and 72.5% of that of LF. In particular, eight different monosaccharides were detected (fucose, arabinose, rhamnose, galactose, glucose, xylose, glucosamine and glucuronic acid), glucuronic acid (46.6%) and rhamnose (29.6%) being the most present monosaccharides in the LF. Almost all the phenol content of LF (113.85 ± 5.87 mg gallic acid eq/g of extract) was water soluble, whereas around 22% of it consisted of flavonoids and only 10% of the flavonoids consisted of anthocyanins. Therefore, LF isolated from egagropili lignocellulosic material could be defined as a water-soluble lignin/carbohydrate complex (LCC) formed by a phenol polymeric chain covalently bound to hemicellulose fragments. LCC exhibited a remarkable antioxidant activity that remained quite stable during 6 months and could be easily incorporated into a protein-based film and released from the latter overtime. These findings suggest egagropili LCC as a suitable candidate as an antioxidant additive for the reinforcement of packaging of foods with high susceptibility to be deteriorated in aerobic conditions.

Genomic-Led Discovery of a Novel Glycopeptide Antibiotic by Nonomuraea coxensis DSM 45129.

Glycopeptide antibiotics (GPAs) are last defense line drugs against multidrug-resistant Gram-positive pathogens. Natural GPAs teicoplanin and vancomycin, as well as semisynthetic oritavancin, telavancin, and dalbavancin, are currently approved for clinical use. Although these antibiotics remain efficient, emergence of novel GPA-resistant pathogens is a question of time. Therefore, it is important to investigate the natural variety of GPAs coming from so-called "rare" actinobacteria. Herein we describe a novel GPA producer-Nonomuraea coxensis DSM 45129. Its de novo sequenced and completely assembled genome harbors a biosynthetic gene cluster (BGC) similar to the dbv BGC of A40926, the natural precursor to dalbavancin. The strain produces a novel GPA, which we propose is an A40926 analogue lacking the carboxyl group on the N-acylglucosamine moiety. This structural difference correlates with the absence of dbv29-coding for an enzyme responsible for the oxidation of the N-acylglucosamine moiety. Introduction of dbv29 into N. coxensis led to A40926 production in this strain. Finally, we successfully applied dbv3 and dbv4 heterologous transcriptional regulators to trigger and improve A50926 production in N. coxensis, making them prospective tools for screening other Nonomuraea spp. for GPA production. Our work highlights genus Nonomuraea as a still untapped source of novel GPAs.

Anomeric configuration-dependence of the Lattrell-Dax epimerization from D-glucose to synthetically useful D-allose derivatives.

D-Allose and its derivatives play important roles in the field of health care and food nutrition. Pure and well-defined D-allose derivatives can facilitate the elucidation of their structure-activity relationship as an essential step for drug design. The Lattrell-Dax epimerization, refers to the triflate inversion using nitrite reagent, is known as valuable method for the synthesis of rare D-allose derivatives. Here, the influence of protecting group patterns on the transformation efficiency of D-glucose derivatives into synthetically useful D-alloses and D-allosamines via the Lattrell-Dax epimerization was studied. For C3 epimerization of D-glucose derivatives bearing O2-acyl group, an anomeric configuration-dependent acyl migration from O2 to O3 was found. In addition, a neighbouring group participation effect-mediated SN1 nucleophilic substitution of the D-glucosamine bearing C2 trichloroacetamido (TCA) group in the Lattrell-Dax epimerization was dependent upon anomeric configuration. Thus, the effect of anomeric configuration on the Lattrell-Dax epimerization of D-glucose suggests that ß-D-glucosides with low steric hindrance at C2 should be better substrates for the synthesis of D-allose derivatives. Significantly, the efficient synthesis of the orthogonally protected D-allose 13 and D-allosamine 18 will serve well for further assembly of complex glycans.

Kinetic Study of Glucosamine Production Using Aspergillus sydowii BCRC 31742 under Solid-State Fermentation.

In the present study, we aimed to obtain a high yield and productivity for glucosamine using a low-cost solid-state culture with Aspergillus sydowii BCRC 31742. The fermentation conditions, such as inoculum biomass, moisture content, and supplemental volume and mineral salt, were chosen to achieve high productivity of glucosamine (GlcN). When the initial supplemental volume used was 3 mL/g substrate, the yield and productivity of GlcN were 48.7 mg/gds and 0.69 mg/gds·h, respectively. This result will be helpful for the industrialization of the process.

Self-Adjuvanting Cancer Vaccines from Conjugation-Ready Lipid A Analogues and Synthetic Long Peptides.

Self-adjuvanting vaccines, wherein an antigenic peptide is covalently bound to an immunostimulating agent, have been shown to be promising tools for immunotherapy. Synthetic Toll-like receptor (TLR) ligands are ideal adjuvants for covalent linking to peptides or proteins. We here introduce a conjugation-ready TLR4 ligand, CRX-527, a potent powerful lipid A analogue, in the generation of novel conjugate-vaccine modalities. Effective chemistry has been developed for the synthesis of the conjugation-ready ligand as well as the connection of it to the peptide antigen. Different linker systems and connection modes to a model peptide were explored, and in vitro evaluation of the conjugates showed them to be powerful immune-activating agents, significantly more effective than the separate components. Mounting the CRX-527 ligand at the N-terminus of the model peptide antigen delivered a vaccine modality that proved to be potent in activation of dendritic cells, in facilitating antigen presentation, and in initiating specific CD8+ T-cell-mediated killing of antigen-loaded target cells in vivo. Synthetic TLR4 ligands thus show great promise in potentiating the conjugate vaccine platform for application in cancer vaccination.

In Silico and In Vitro Analyses of Glucosamine and Indole Acetaldehyde Inhibit Pathogenic Regulator Gene phcA of Ralstonia solanacearum, a Causative Agent of Bacterial Wilt of Tomato.

In this study, medicinal plant (Solanum surattense)-associated bacteria were isolated and their extracellular secondary metabolites were extracted. Dual-plate application of crude secondary metabolites proved that SSL2I and SSL5 had a good inhibitory activity against Ralstonia solanacearum. These biocontrol bacteria were identified as Bacillus subtilis and Bacillus velezensis by 16S rRNA gene sequencing analysis. The crude extracts of secondary metabolites were identified based on high-resolution liquid chromatography/mass spectrometry (HR-LCMS) analysis. On the basis of HR-LCMS analysis, we selected the compounds such as glucosamine and indole acetaldehyde for in silico analysis and inhibition of pathogenic gene of phcA from R. solanacearum. The specificity of identified pathogenic gene of R. solanacearum and its cytoplasmic localization were identified by BLASTP and PSORTB bioinformatics tools. The protein-protein interaction between the identified secondary metabolites and pathogenic gene revealed that the compound had antagonistic potential against pathogenic gene of phcA. Furthermore, the synthetic forms of the above metabolites showed that both the compounds had the ability to inhibit R. solanacearum under in vitro condition. On the basis of in silico and in vitro analyses, it was concluded that medicinal plant-associated Bacillus spp. could be used as a biocontrol agent in managing wilt disease caused by R. solanacearum.

Evaluation of Chondroprotective Activity of Channa striatus in Rabbit Osteoarthritis Model.

OBJECTIVES: The objective of the study is to evaluate the chondroprotective activity of Channa striatus (Channa) and glucosamine sulphate (glucosamine) on histomorphometric examinations, serum biomarker, and inflammatory mediators in experimental osteoarthritis (OA) rabbit model. DESIGN: Anterior cruciate ligament transection (ACLT) was performed to induce OA in thirty-three male New Zealand white rabbits and were randomly divided into three groups: Channa, glucosamine, and control group. The control group received drinking water and the Channa and glucosamine groups were orally administered with 51.4 mg/kg of Channa extract and 77.5 mg/kg of glucosamine sulphate in drinking water, respectively, for eight weeks and then sacrificed. The articular cartilage was evaluated macroscopically and histologically using semiquantitative and quantitative methods. Serum cartilage oligomeric matric protein (COMP), cyclooxygenase 2 (COX-2) enzyme, and prostaglandin E2 (PGE2) were also determined. RESULTS: Macroscopic analysis revealed that Channa group have a significantly lower severity grade of total macroscopic score compared to the control (p < 0.001) and glucosamine (p < 0.05) groups. Semiquantitative histology scoring showed that both Channa and glucosamine groups had lower severity grading of total histology score compared to the control group (p < 0.001). In comparison with the control, Channa group had lower histopathological changes in three compartments of the joint compared to glucosamine group which had lower histological scoring in two compartments only. The cartilage thickness, area, and roughness of both Channa (p < 0.05) and glucosamine (p < 0.05) groups were superior compared to the control group. However, the Channa group demonstrated significantly less cartilage roughness compared to the glucosamine group (p < 0.05). Serum COMP levels were lower in both Channa (p < 0.05) and glucosamine (p < 0.05) groups compared to the control group. CONCLUSION: Both oral administration of Channa extract and glucosamine exhibited chondroprotective action on an ACLT OA-induced rabbit model. However, Channa was superior to glucosamine in maintaining the structure of the cartilage.

Glucosamine Protects Rat Bone Marrow Cells Against Cisplatin-induced Genotoxicity and Cytotoxicity.

BACKGROUND AND OBJECTIVE: Glucosamine is a widely prescribed dietary supplement used in the treatment of osteoarthritis. In the present study, the chemoprotectant ability of glucosamine was evaluated against cisplatin-induced genotoxicity and cytotoxicity in rat bone marrow cells. METHODS: Glucosamine was orally administrated to rats at doses of 75 and 150 mg/kg body weight for seven consecutive days. On the seventh day, the rats were treated with a single injection of cisplatin (5 mg/kg, i.p.) at 1h after the last oral administration. The cisplatin antagonistic potential of glucosamine was assessed by micronucleus assay, Reactive Oxygen Species (ROS) level analysis, hematological analysis, and flow cytometry. RESULTS: Glucosamine administration to cisplatin-treated rats significantly decreased the frequencies of Micronucleated Polychromatic Erythrocytes (MnPCEs) and Micronucleated Normchromatic Erythrocytes (MnNCEs), and also increased PCE/(PCE+NCE) ratio in bone marrow cells. Furthermore, treatment of rats with glucosamine before cisplatin significantly inhibited apoptosis, necrosis and ROS generation in bone marrow cells, and also increased red blood cells count in peripheral blood. CONCLUSION: This study shows glucosamine to be a new effective chemoprotector against cisplatin-induced DNA damage and apoptosis in rat bone marrow cells. The results of this study may be helpful in reducing the harmful effects of cisplatin-based chemotherapy in the future.

Enhanced Antiarthritic Efficacy by Nanoparticles of (-)-Epigallocatechin Gallate-Glucosamine-Casein.

This work aims to improve the antiarthritic activity of (-)-epigallocatechin gallate (EGCG) and glucosamine (GA) through fabrication and optimization of casein protein nanoparticles (EGC-NPs). Optimized EGC-NPs were obtained with a EGCG/GA/casein ratio of 1:2:8 (w/w/w). The EGC-NPs gave a mean size of 186 ± 3.5 nm and an entrapment efficiency of 86.8 ± 2.7%, and they exhibited a greater inhibitory activity against human fibroblast-like synoviocytes-osteoarthritis cells and human fibroblast-like synoviocytes-rheumatoid arthritis cells compared with that of the EGCG-GA mixture by 33.5% and 20.8%, respectively. Freeze-dried EGC-NPs stored at 25 °C during 12 months showed high dispersion stability. Moreover, the redispersion of the freeze-dried EGC-NPs produced almost no significant changes in their physicochemical properties and bioactivity. Rat experiments demonstrated that the antiarthritis effect of the EGC-NPs was significantly higher than that of EGCG-GA mixture, as assessed through an analysis of anti-inflammatory efficacy, radiographic images and histopathological assessments of paw joints, and immunohistochemical changes in serum cytokines. The enchanced antiarthritic activity in vivo was consistent with that in vitro. The EGC-NPs demonstrate potential as a food supplement for the treatment of arthritis.

Glucosamine for the Treatment of Osteoarthritis: The Time Has Come for Higher-Dose Trials.

Although clinical trials with glucosamine in osteoarthritis have yielded mixed results, leading to doubts about its efficacy, the utility of glucosamine for preventing joint destruction and inflammation is well documented in rodent models of arthritis, including models of spontaneous osteoarthritis. The benefit of oral glucosamine in adjuvant arthritis is markedly dose dependent, likely reflecting a modulation of tissue levels of UDP-N-acetylglucosamine that in turn influences mucopolysaccharide synthesis and the extent of protein O-GlcNAcylation. Importantly, the minimal oral dose of glucosamine that exerts a detectible benefit in adjuvant arthritis achieves plasma glucosamine levels similar to those achieved when the standard clinical dose of glucosamine, 1.5 g daily, is administered as a bolus. The response of plasma glucosamine levels to an increase in glucosamine intake is nearly linear. Remarkably, every published clinical trial with glucosamine has employed the same 1.5 g dose that Rottapharm recommended for its proprietary glucosamine sulfate product decades ago, yet there has never been any published evidence that this dose is optimal with respect to efficacy and side effects. If this dose is on the edge of demonstrable clinical efficacy when experimental design is ideal, then variations in the patient populations targeted, the assessment vehicles employed, and the potency of glucosamine preparations tested could be expected to yield some null results. Failure to employ bolus dosing may also be a factor in the null results observed in the GAIT study and other trials. Clinical studies evaluating the dose dependency of glucosamine's influence on osteoarthritis are long overdue.

Antimicrobial photodynamic therapy alone or in combination with antibiotic local administration against biofilms of Fusobacterium nucleatum and Porphyromonas gingivalis.

Antimicrobial photodynamic therapy (aPDT) kills several planktonic pathogens. However, the susceptibility of biofilm-derived anaerobic bacteria to aPDT is poorly characterized. Here, we evaluated the effect of Photodithazine (PDZ)-mediated aPDT on Fusobacterium nucleatum and Porphyromonas gingivalis biofilms. In addition, aPDT was tested with metronidazole (MTZ) to explore the potential antimicrobial effect of the treatment. The minimum inhibitory concentration (MIC) of MTZ was defined for each bacterial species. Single-species biofilms of each species were grown on polystyrene plates under anaerobic conditions for five days. aPDT was performed by applying PDZ at concentrations of 50, 75 and 100 mg/L, followed by exposure to 50 J/cm2 LED light (660 nm) with or without MTZ. aPDT exhibited a significant reduction in bacterial viability at a PDZ concentration of 100 mg/L, with 1.12 log10 and 2.66 log10 reductions for F. nucleatum and P. gingivalis in biofilms, respectively. However, the antimicrobial effect against F. nucleatum was achieved only when aPDT was combined with MTZ at 100× MIC. Regarding P. gingivalis, the combination of PDZ-mediated aPDT at 100 mg/L with MTZ 100× MIC resulted in a 5 log10 reduction in the bacterial population. The potential antimicrobial effects of aPDT in combination with MTZ for both single pathogenic biofilms were confirmed by live/dead staining. These results suggest that localized antibiotic administration may be an adjuvant to aPDT to control F. nucleatum and P. gingivalis biofilms.

Influence of Excipients on the Antimicrobial Activity of Tobramycin Against Pseudomonas aeruginosa Biofilms.

PURPOSE: It is unknown if inactive pharmaceutical ingredients influence the activity of antibiotics they are co-formulated with. Recently it was found that materials acting as carbon nutrient sources for bacteria can promote bacterial dispersion from a biofilm and/or reverse the persister state of a subpopulation of bacteria within the biofilms. Both can make bacteria more susceptible to antibiotics. Thus, the aim was to identify potential excipients to improve antibiotic activity in Pseudomonas aeruginosa biofilms. METHODS: We screened 190 potential excipients alone, and in combination with tobramycin sulfate against P. aeruginosa (strain PAO1) grown planktonically or as biofilms. After the excipient screening stage, we investigated the effect of 10 selected excipients against a more virulent strain (luminescent strain UCBPP-PA14). Temporal changes in luminescence, as an indicator of bacterial proliferation, and surviving colony forming units (CFUs) from the treated PA14 biofilms were quantified. RESULTS: Forty-eight materials tested caused a reduction of PAO1 proliferation either alone or combined with tobramycin. L-alanine (p < 0.05), D-alanine (p > 0.05), and N-acetyl-D-glucosaminitol (p > 0.05) improved the activity of tobramycin measured by PA14 luminometry. Additionally, L-alanine and succinic acid significantly reduced the survival of PA14 biofilms (p < 0.05). CONCLUSIONS: L-alanine, succinic acid, and N-acetyl-D-glucosaminitol may be useful as antibiotic adjuvants in future tobramycin anti-biofilm formulations.

Geriatric-Oriented High Dose Nutraceutical ODTs: Formulation and Physicomechanical Characterization.

CONTEXT: Oral disintegrating tablets (ODTs) represent a better option than conventional tablets for geriatric population, owing to their fast onset of action and their better patient compliance. OBJECTIVE: Two principal therapeutic high-dose nutraceuticals; chondroitin sulphate and glucosamine were formulated into an oral disintegration tablet (ODT) intended for sublingual administration, and optimized to improve compliance and achieve rapid onset of action in osteoarthritis treatment. MATERIALS AND METHODS: Different formulations were prepared either by melt granulation or direct compression techniques. Excipients at different ratios such as superdisintegrants, pharmaburst™ C1, spray-dried mannitol, and polyethylene glycols were used to enhance the disintegration time for the ODT systems. RESULTS: Although the ODT systems weighed around 1.3 gm with 60% drug load, some systems disintegrated within 2-3 min with 100% drug release. Pharmaburst™ C1 turned out to be the key excipient responsible for the superdisintegration properties of the ODTs. Dissolution enhancement of the two nutraceuticals could be achieved compared to the marketed conventional tablets. CONCLUSION: The improved disintegration and dissolution properties of our prepared ODTs are expected to enhance the bioavailability of the high dose glucosamine and chondroitin sulphate in comparison with conventional tablets, which delineates them as a promising dosage form for the aforementioned nutraceuticals.

Glucosamine and N-acetyl glucosamine as new CEST MRI agents for molecular imaging of tumors.

The efficacy of glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) as agents for chemical exchange saturation transfer (CEST) magnetic resonance molecular imaging of tumors is demonstrated. Both agents reflect the metabolic activity and malignancy of the tumors. The method was tested in two types of tumors implanted orthotopically in mice: 4T1 (mouse mammary cancer cells) and MCF7 (human mammary cancer cells). 4T1 is a more aggressive type of tumor than MCF7 and exhibited a larger CEST effect. Two methods of administration of the agents, intravenous (IV) and oral (PO), gave similar results. The CEST MRI observation of lung metastasis was confirmed by histology. The potential of the clinical application of CEST MRI with these agents for cancer diagnosis is strengthened by their lack of toxicity as can be indicated from their wide use as food supplements.

Novel biologically active series of N-acetylglucosamine derivatives for the suppressive activities on GAG release.

(d)-Glucosamine and other nutritional supplements have emerged as safe alternative therapies for osteoarthritis, a chronic and degenerative articular joint disease. N-acetyl-(d)-glucosamine, a compound that can be modified at the N position, is considered to improve the oral bioavailability of (d)-glucosamine and has been proven to possess greater in vitro chondroprotective activity compared with the parent agent. In this study, to further utilize these properties, we focus on the modification of the N position with a benzenesulfonyl and different isoxazole formyl groups. Among these compounds, the 3-(2-chlorobenzene)-5-methyl-isoxazole formyl chloride and p-methoxybenzenesulfonyl chloride modifying structures proved to be the most active of the series and efficiently processed the chondrocytes in vitro. These novel N-position substitution compounds may represent promising leads for osteoarthritis drug development.

Droplet-based glucosamine sensor using gold nanoparticles and polyaniline-modified electrode.

A droplet-based electrochemical sensor for direct measurement of D-glucosamine was developed using carbon paste electrodes (CPEs) modified with gold nanoparticles (AuNPs) and polyaniline (PANI). Central composition design (CCD) was employed as a powerful method for optimization of parameters for electrode fabrication. The optimized amounts of AuNPs and PANI obtained from the response surface were determined as 300 and 3000mgL(-1), respectively. Coupled with a droplet microfluidic system, the analysis of glucosamine was performed in a high-throughput manner with a sample throughput of at least 60 samples h(-1). In addition, the adsorption of the analyte on the electrode surface was prevented due to compartmentalization in droplets. Linearity of the proposed system was found to be in the range of 0.5-5mM with a sensitivity of 7.42×10(-3)Amol(-1)Lcm(-2) and limits of detection and quantitation of 0.45 and 1.45mM, respectively. High intraday and interday (evaluated among 3 days) precisions for the detection of 50 droplets containing glucosamine were obtained with relative standard deviation less than 3%. The system was successfully used to determine the amounts of glucosamine in supplementary products with error percentage and relative standard deviation less than 3%. In addition, the amounts of glucosamine measured using the developed sensor were in good agreement with those obtained from a CE method. These indicate high accuracy and precision of the proposed system.

Enhanced oral bioavailability of a novel folate salt: comparison with folic acid and a calcium folate salt in a pharmacokinetic study in rats.

BACKGROUND: Folates play an important role to prevent neurological disorders in embryo development and in cardiovascular diseases. Folate supplementation is suggested, particularly in females of childbearing age, for the prevention of embryonal NTDs during pregnancy. Folic acid and reduced folate ((6S)5-MTHF) are currently used in supplementation. The aim of this study was to compare the bioavailability of Quatrefolic®, a novel patented (6S)5-MTHF glucosamine salt, with (6S)5-MTHF calcium salt and folic acid in Sprague Dawley rats. METHODS: Fifty-four to fifty-five-day old male Sprague-Dawley rats were divided in 3 treatment groups, each comprising 6 animals, receiving folic acid, (6S)5-MTHF calcium salt or Quatrefolic® at the dose of 70 µg/kg of (6S)5-MTHF equivalents in a single oral administration. Folates were determined in plasma with a HPLC method employing fluorimetric detection. (6S)5-MTHF level was chosen as a convenient end point to evaluate folate absorption. The main pharmacokinetic parameters were calculated (Cmax, tmax, AUC). RESULTS: Quatrefolic® administration produced a plasmatic (6S)5-MTHF concentration peak (Cmax: 879.6±330.3 ng/mL) 1.8 times higher than (6S)5-MTHF Ca salt (486.8±184.1 ng/mL), and 3.1 times higher than folic acid supplementation (281.5±135.7 ng/mL), while tmax values were similar for the three folate forms. Quatrefolic® supplementation showed AUC8h (1123.9 ng/mL ∙ h) 9.7 times higher than folic acid (114.7 ng/mL ∙ h) and 1.12 times higher than (6S)5-MTHF Ca salt (997.6 ng/mL ∙ h). CONCLUSIONS: Quatrefolic® has demonstrated an enhanced oral bioavailability in comparison to other reduced folates and to folic acid in rats.

White kidney bean lectin exerts anti-proliferative and apoptotic effects on cancer cells.

A 60-kDa glucosamine binding lectin, white kidney bean lectin (WKBL), was purified from Phaseolus vulgaris cv. white kidney beans, by application of anion exchange chromatography on Q-Sepharose, affinity chromatography on Affi-gel blue gel, and FPLC-size exclusion on Superdex 75. The anti-proliferative activity of WKBL on HONE1 cells and HepG2 cells was stronger than the activity on MCF7 cells and WRL68 cells (IC50 values for a 48-h treatment with WKBL on HONE1 cells: 18.8 µM; HepG2 cells: 19.7 µM; MCF7 cells: 26.9 µM; and WRL68 cells: >80 µM). The activity could be reduced by addition of glucosamine, which occupies the binding sites of WKBL, indicating that carbohydrate binding is crucial for the activity. Annexin V-FITC and PI staining, JC-1 staining and Hoechst 33342 staining revealed that apoptosis was induced on WKBL-treated HONE1 cells and HepG2 cells, but not as obviously on MCF7 cells. Cell cycle analysis also showed a slight cell cycle arrest on HONE1 cells after WKBL treatment. Western blotting suggested that WKBL induced apoptosis of HONE1 cells occurred through the extrinsic apoptosis pathway, with detection of increased level of active caspase 3, 8 and 9.

Glucosamine Modulates T Cell Differentiation through Down-regulating N-Linked Glycosylation of CD25.

Glucosamine has immunomodulatory effects on autoimmune diseases. However, the mechanism(s) through which glucosamine modulates different T cell subsets and diseases remain unclear. We demonstrate that glucosamine impedes Th1, Th2, and iTreg but promotes Th17 differentiation through down-regulating N-linked glycosylation of CD25 and subsequently inhibiting its downstream Stat5 signaling in a dose-dependent manner. The effect of glucosamine on T helper cell differentiation was similar to that induced by anti-IL-2 treatment, further supporting an IL-2 signaling-dependent modulation. Interestingly, excess glucose rescued this glucosamine-mediated regulation, suggesting a functional competition between glucose and glucosamine. High-dose glucosamine significantly decreased Glut1 N-glycosylation in Th1-polarized cells. This finding suggests that both down-regulated IL-2 signaling and Glut1-dependent glycolytic metabolism contribute to the inhibition of Th1 differentiation by glucosamine. Finally, glucosamine treatment inhibited Th1 cells in vivo, prolonged the survival of islet grafts in diabetic recipients, and exacerbated the severity of EAE. Taken together, our results indicate that glucosamine interferes with N-glycosylation of CD25, and thereby attenuates IL-2 downstream signaling. These effects suggest that glucosamine may be an important modulator of T cell differentiation and immune homeostasis.