Neonatal Exposure to Commensal-Bacteria-Derived Antigens Directs Polysaccharide-Specific B-1 B Cell Repertoire Development.

B-1 B cells derive from a developmental program distinct from that of conventional B cells, through B cell receptor (BCR)-dependent positive selection of fetally derived precursors. Here, we used direct labeling of B cells reactive with the N-acetyl-D-glucosamine (GlcNAc)-containing Lancefield group A carbohydrate of Streptococcus pyogenes to study the effects of bacterial antigens on the emergent B-1 B cell clonal repertoire. The number, phenotype, and BCR clonotypes of GlcNAc-reactive B-1 B cells were modulated by neonatal exposure to heat-killed S. pyogenes bacteria. GlcNAc-reactive B-1 clonotypes and serum antibodies were reduced in germ-free mice compared with conventionally raised mice. Colonization of germ-free mice with a conventional microbiota promoted GlcNAc-reactive B-1 B cell development and concomitantly elicited clonally related IgA+ plasma cells in the small intestine. Thus, exposure to microbial antigens in early life determines the clonality of the mature B-1 B cell repertoire and ensuing antibody responses, with implications for vaccination approaches and schedules.

Glucosamine-Mediated Hexosamine Biosynthesis Pathway Activation Uses ATF4 to Promote "Exercise-Like" Angiogenesis and Perfusion Recovery in PAD.

BACKGROUND: Endothelial cells (ECs) use glycolysis to produce energy. In preclinical models of peripheral arterial disease, further activation of EC glycolysis was ineffective or deleterious in promoting hypoxia-dependent angiogenesis, whereas pentose phosphate pathway activation was effective. Hexosamine biosynthesis pathway, pentose phosphate pathway, and glycolysis are closely linked. Glucosamine directly activates hexosamine biosynthesis pathway. METHODS: Hind-limb ischemia in endothelial nitric oxide synthase knockout (eNOS-/-) and BALB/c mice was used. Glucosamine (600 µg/g per day) was injected intraperitoneally. Blood flow recovery was assessed using laser Doppler perfusion imaging and angiogenesis was studied by CD31 immunostaining. In vitro, human umbilical vein ECs and mouse microvascular ECs with glucosamine, L-glucose, or vascular endothelial growth factor (VEGF165a) were tested under hypoxia and serum starvation. Cell Counting Kit-8, tube formation, intracellular reactive oxygen species, electric cell-substrate impedance sensing, and fluorescein isothiocyanate dextran permeability were assessed. Glycolysis and oxidative phosphorylation were assessed by seahorse assay. Gene expression was assessed using RNA sequencing, real-time quantitative polymerase chain reaction, and Western blot. Human muscle biopsies from patients with peripheral arterial disease were assessed for EC O-GlcNAcylation before and after supervised exercise versus standard medical care. RESULTS: On day 3 after hind-limb ischemia, glucosamine-treated versus control eNOS-/- mice had less necrosis (n=4 or 5 per group). Beginning on day 7 after hind-limb ischemia, glucosamine-treated versus control BALB/c mice had higher blood flow, which persisted to day 21, when ischemic muscles showed greater CD31 staining per muscle fiber (n=8 per group). In vitro, glucosamine versus L-glucose ECs showed improved survival (n=6 per group) and tube formation (n=6 per group). RNA sequencing of glucosamine versus L-glucose ECs showed increased amino acid metabolism (n=3 per group). That resulted in increased oxidative phosphorylation (n=8-12 per group) and serine biosynthesis pathway without an increase in glycolysis or pentose phosphate pathway genes (n=6 per group). This was associated with better barrier function (n=6-8 per group) and less reactive oxygen species (n=7 or 8 per group) compared with activating glycolysis by VEGF165a. These effects were mediated by activating transcription factor 4, a driver of exercise-induced angiogenesis. In muscle biopsies from humans with peripheral arterial disease, EC/O-GlcNAcylation was increased by 12 weeks of supervised exercise versus standard medical care (n=6 per group). CONCLUSION: In cells, mice, and humans, activation of hexosamine biosynthesis pathway by glucosamine in peripheral arterial disease induces an "exercise-like" angiogenesis and offers a promising novel therapeutic pathway to treat this challenging disorder.

Diosgenyl glucosamine conjugates increase pro-apoptotic and selective activities in cancer cell lines.

BACKGROUND INFORMATION: Antiproliferative and apoptotic activities have been attributed to the phytosteroid diosgenin ((25R)-spirost-5-en-3ß-ol; 1). It is known that combining glucose with two rhamnoses (the chacotrioside framework) linked to diosgenin increases its apoptotic activity. However, the effects of diosgenin glucosamine glycosides on different cancer cell types and cell death have not been entirely explored. RESULTS: This study reports the antiproliferative, cytotoxic, and apoptotic activities of diosgenin and its glycosylated derivative ((25R)-spirost-5-en-3ß-yl ß-D-glucopyranoside; 2). It also explores the effects of two diosgenin glucosamine derivates, diosgenin 2-acetamido-2-deoxy-ß-D-glucopyranoside (3), and diosgenin 2-amino-2-deoxy-ß-D-glucopyranoside hydrochloride (4), on different cancer cell lines. We found that all the compounds affected proliferative activity with minimal toxicity. In addition, all cancer cell lines showed morphological and biochemical characteristics corresponding to an apoptotic process. Apoptotic cell death was higher in all cell lines treated with compounds 2, 3 and 4 than in those treated with diosgenin. Moreover, compounds 3 and 4 induced apoptosis better than compounds 1 and 2. These results suggest that combining glucosamine with modified glucosamine attached to diosgenin has a greater apoptotic effect than diosgenin or its glycosylated derivative (compound 2). Furthermore, diosgenin and the abovementioned glycosides had a selective effect on tumour cells since the proliferative capacity of human lymphocytes, keratinocytes (HaCaT) and epithelial cells (CCD841) was not significantly affected. CONCLUSIONS: Altogether, these results demonstrate that diosgenin glucosamine compounds exert an antiproliferative effect on cancer cell lines and induce apoptotic effects more efficiently than diosgenin alone without affecting non-tumour cells. SIGNIFICANCE: This study evidences the pro-apoptotic and selective activities of diosgenyl glucosamine compounds in cancer cell lines.

Effect of reducing isoflurane level on glucosamine uptake in the mouse brain during magnetic resonance imaging studies.

Anesthesia is often required during magnetic resonance imaging (MRI) examinations in animal studies. Anesthetic drugs differ in their capacity to interfere with homeostatic mechanisms responsible for glucose metabolism in the brain, which may create a constraint in the study design. Recent studies suggest that the chemical exchange saturation transfer (CEST) MRI scanning technique can detect localized metabolic changes in rodent brains induced by the uptake of glucose or its analogs; however, most of these studies do not account for the impact of anesthesia type on the brain metabolism. Herein, we aimed to evaluate the effect of reduced isoflurane levels on the preclinical imaging of glucosamine (GlcN) uptake in healthy mouse brains to establish optimal conditions for future brain imaging studies using the CEST MRI technique. The commonly used anesthesia protocol for longitudinal MRI examinations using 1.5% isoflurane level was compared to that using a mixture of low isoflurane (0.8%) level combined with midazolam (2 mg/kg, SC). Magnetization transfer ratio asymmetry (MTRasym) and area under the curve (AUC) analyses were used to characterize GlcN signals in the brain. The results indicated that mice injected with GlcN and anesthetized with 1.5% isoflurane exhibited low and insignificant changes in the MTRasym and AUC signals in the frontal cortex, whereas mice administered with 0.8% isoflurane combined with midazolam demonstrated a significant increase in these signals in the frontal cortex. This study highlights the diverse GlcN metabolic changes observed in mouse brains under variable levels of isoflurane anesthesia using the CEST MRI method. The results suggest that it is feasible to maintain anesthesia with low-dose isoflurane by integrating midazolam, which may enable the investigation of GlcN uptake in the brain. Thus, reducing isoflurane levels may support studies into mouse brain metabolism using the CEST MRI method and should be considered in future studies.

Small RNA-binding protein RapZ mediates cell envelope precursor sensing and signaling in Escherichia coli.

The RNA-binding protein RapZ cooperates with small RNAs (sRNAs) GlmY and GlmZ to regulate the glmS mRNA in Escherichia coli. Enzyme GlmS synthesizes glucosamine-6-phosphate (GlcN6P), initiating cell envelope biosynthesis. GlmZ activates glmS expression by base-pairing. When GlcN6P is ample, GlmZ is bound by RapZ and degraded through ribonuclease recruitment. Upon GlcN6P depletion, the decoy sRNA GlmY accumulates through a previously unknown mechanism and sequesters RapZ, suppressing GlmZ decay. This circuit ensures GlcN6P homeostasis and thereby envelope integrity. In this work, we identify RapZ as GlcN6P receptor. GlcN6P-free RapZ stimulates phosphorylation of the two-component system QseE/QseF by interaction, which in turn activates glmY expression. Elevated GlmY levels sequester RapZ into stable complexes, which prevents GlmZ decay, promoting glmS expression. Binding of GlmY also prevents RapZ from activating QseE/QseF, generating a negative feedback loop limiting the response. When GlcN6P is replenished, GlmY is released from RapZ and rapidly degraded. We reveal a multifunctional sRNA-binding protein that dynamically engages into higher-order complexes for metabolite signaling.

pH and ROS Dual-Sensitive Nanocarriers for the Targeted Co-Delivery and On-Demand Sequential Release of Tofacitinib and Glucosamine for Synergistic Rheumatoid Arthritis Treatment.

Rheumatoid arthritis (RA) progression involves multiple cell types, and sequential drug action on target cells is necessary for RA treatment. Nanocarriers are widely used for RA treatment; however, the targeted delivery and on-demand release of multiple drugs remains challenging. Therefore, in this study, a dual-sensitive polymer is developed using chondroitin sulfate (CS) for the co-delivery of the cartilage repair agent, glucosamine (GlcN), and anti-inflammatory drug, tofacitinib (Tof). In the joint cavity, acidic pH facilitates the cleavage of GlcN from CS polymer to repair the cartilage damage. Subsequently, macrophage uptake via CS-CD44 binding and intracellular reactive oxygen species (ROS) mediate conversion of (methylsulfanyl)propylamine to a hydrophilic segment jointly triggered rapid Tof/GlcN release via micelle disassembly. The combined effects of Tof, GlcN, and ROS depletion promote the M1-to-M2 polarization shift to attenuate inflammation. The synergistic effects of these agents against RA are confirmed in vitro and in vivo. Overall, the dual pH/ROS-sensitive CS nanoplatform simultaneously delivers GlcN and Tof, providing a multifunctional approach for RA treatment with synergistic drug effects.

Study of two glycosyltransferases related to polysaccharide biosynthesis in Rhodococcus jostii RHA1.

The bacterial genus Rhodococcus comprises organisms performing oleaginous behaviors under certain growth conditions and ratios of carbon and nitrogen availability. Rhodococci are outstanding producers of biofuel precursors, where lipid and glycogen metabolisms are closely related. Thus, a better understanding of rhodococcal carbon partitioning requires identifying catalytic steps redirecting sugar moieties to storage molecules. Here, we analyzed two GT4 glycosyl-transferases from Rhodococcus jostii (RjoGlgAb and RjoGlgAc) annotated as α-glucan-α-1,4-glucosyl transferases, putatively involved in glycogen synthesis. Both enzymes were produced in Escherichia coli cells, purified to homogeneity, and kinetically characterized. RjoGlgAb and RjoGlgAc presented the "canonical" glycogen synthase activity and were actives as maltose-1P synthases, although to a different extent. Then, RjoGlgAc is a homologous enzyme to the mycobacterial GlgM, with similar kinetic behavior and glucosyl-donor preference. RjoGlgAc was two orders of magnitude more efficient to glucosylate glucose-1P than glycogen, also using glucosamine-1P as a catalytically efficient aglycon. Instead, RjoGlgAb exhibited both activities with similar kinetic efficiency and preference for short-branched α-1,4-glucans. Curiously, RjoGlgAb presented a super-oligomeric conformation (higher than 15 subunits), representing a novel enzyme with a unique structure-to-function relationship. Kinetic results presented herein constitute a hint to infer on polysaccharides biosynthesis in rhodococci from an enzymological point of view.

Habitual use of glucosamine and adverse liver outcomes among patients with type 2 diabetes and MASLD.

BACKGROUND: Glucosamine is a dietary supplement commonly used to support joint health. However, there has been interest in exploring other effects of glucosamine on health outcomes due to its ant-inflammation effect. OBJECTIVE: This study compared the risks of major adverse liver outcomes (MALOs) between regular users and non-users of glucosamine among patients with type 2 diabetes and metabolic dysfunction associated steatotic liver disease (MASLD) using the data from a large prospective cohort study. METHODS: Demographic, anthropometric, laboratory and medication prescription information among 18 753 patients with type 2 diabetes and MASLD was obtained from the UK Biobank. MASLD was identified based on hepatic steatosis defined by fatty liver index ≥60 plus the presence of any clues of metabolic dysregulation and cardio-metabolic risk factors, excluding patients with moderate to severe alcohol consumption. RESULTS: During a mean follow-up of 11.4 years, 826 incident MALOs events were recorded. Patients not regularly using glucosamine compared with patients using glucosamine showed a significantly higher risk of the composite MALOs (HR 1.36, 95% confidence interval [CI] 1.09-1.69) as well as most individual MALOs except for ascites. The multivariable-adjusted HRs of MALOs within 3, 5 and 10 years among non-users of glucosamine compared with regular users were 1.79 (95% CI .69-2.03), 1.88 (95% CI 1.21-2.54) and 1.32 (95% CI 1.05-1.72), respectively. Further subgroup analyses in participants with different baseline characteristics and sensitivity analyses excluding participants who regularly took any other supplements and participants who used self-reports to diagnose diabetes confirmed the findings. CONCLUSIONS: The present study indicated that habitual use of glucosamine was associated with a low risk of individual and composite MALOs among patients with type 2 diabetes and MASLD.

Mitochondrial DNA variants and microbiota: An experimental strategy to identify novel therapeutic potential in chronic inflammatory diseases.

We previously demonstrated that mice carrying natural mtDNA variants of the FVB/NJ strain (m.7778 G>T in the mt-Atp8 gene in mitochondrial complex V), namely C57BL/6 J-mtFVB/NJ (B6-mtFVB), exhibited (i) partial protection from experimental skin inflammatory diseases in an anti-murine type VII collagen antibody-induced skin inflammation model and psoriasiform dermatitis model; (ii) significantly altered metabolites, including short-chain fatty acids, according to targeted metabolomics of liver, skin and lymph node samples; and (iii) a differential composition of the gut microbiota according to bacterial 16 S rRNA gene sequencing of stool samples compared to wild-type C57BL/6 J (B6) mice. To further dissect these disease-contributing factors, we induced an experimental antibody-induced skin inflammatory disease in gnotobiotic mice. We performed shotgun metagenomic sequencing of caecum contents and untargeted metabolomics of liver, CD4+ T cell, and caecum content samples from conventional B6-mtFVB and B6 mice. We identified D-glucosamine as a candidate mediator that ameliorated disease severity in experimental antibody-induced skin inflammation by modulating immune cell function in T cells, neutrophils and macrophages. Because mice carrying mtDNA variants of the FVB/NJ strain show differential disease susceptibility to a wide range of experimental diseases, including diet-induced atherosclerosis in low-density lipoprotein receptor knockout mice and collagen antibody-induced arthritis in DBA/1 J mice, this experimental approach is valuable for identifying novel therapeutic options for skin inflammatory conditions and other chronic inflammatory diseases to which mice carrying specific mtDNA variants show differential susceptibility.

Preliminary evidence for therapeutic impact of intravesical glucosamine on protamine sulfate and potassium chloride-induced bladder overactivity in rat model.

PURPOSE: To investigate the protective effect of intravesical glucosamine in treating overactive bladder (OAB). METHODS: Ninety-two female Sprague-Dawley (SD) rats were divided into 4 groups i.e. protamine sulfate (PS), N-acetylcysteine (NAC), and glucosamine-treated PS (GPS), and normal saline control (NC) were used. We induced hyperactivity in rats via intravesical infusion of PS and potassium chloride (KCl), whereas the NC group underwent a sustained intravesical saline infusion for 1 h. N-acetylcysteine (NAC), a potential antioxidant as well as anti-inflammatory agent was employed as positive control. Cystometrography (CMG) was then conducted to determine urodynamic parameters, i.e., leak point pressure (LPP, n = 48) and inter-contractile interval, the duration between two voids (ICI, n = 32). RESULTS: LPP was significantly elevated in the GPS group (mean ± SD: 110.9 ± 6.2 mmHg) compared to the NC (81.0 ± 32.5 mmHg), PS (40.3 ± 10.9 mmHg), and NAC group (70.3 ± 19.4 mmHg). The cystometrogram data also reveals a prolonged ICI in the GPS group (241.3 ± 40.2 s) compared to the NC group (216.0 ± 41.7 s), PS group (128.8 ± 23.6 s), and NAC group (193.8 ± 28.3 s). CONCLUSION: This preliminary study implies the ameliorative impact of GPS treatment on OAB in terms of improved urodynamic parameters, including LPP and ICI.

Maribacter halichondriae sp. nov., isolated from the marine sponge Halichondria panicea, displays features of a sponge-associated life style.

A new member of the family Flavobacteriaceae (termed Hal144T) was isolated from the marine breadcrumb sponge Halichondria panicea. Sponge material was collected in 2018 at Schilksee which is located in the Kiel Fjord (Baltic Sea, Germany). Phylogenetic analysis of the full-length Hal144T 16S rRNA gene sequence revealed similarities from 94.3 to 96.6% to the nearest type strains of the genus Maribacter. The phylogenetic tree of the 16S rRNA gene sequences depicted a cluster of strain Hal144T with its closest relatives Maribacter aestuarii GY20T (96.6%) and Maribacter thermophilus HT7-2T (96.3%). Genome phylogeny showed that Maribacter halichondriae Hal144T branched from a cluster consisting of Maribacter arenosus, Maribacter luteus, and Maribacter polysiphoniae. Genome comparisons of strain Maribacter halichondriae Hal144T with Maribacter sp. type strains exhibited average nucleotide identities in the range of 75-76% and digital DNA-DNA hybridisation values in the range of 13.1-13.4%. Compared to the next related type strains, strain Hal144T revealed unique genomic features such as phosphoenolpyruvate-dependent phosphotransferase system pathway, serine-glyoxylate cycle, lipid A 3-O-deacylase, 3-hexulose-6-phosphate synthase, enrichment of pseudogenes and of genes involved in cell wall and envelope biogenesis, indicating an adaptation to the host. Strain Hal144T was determined to be Gram-negative, mesophilic, strictly aerobic, flexirubin positive, resistant to aminoglycoside antibiotics, and able to utilize N-acetyl-ß-D-glucosamine. Optimal growth occurred at 25-30 °C, within a salinity range of 2-6% sea salt, and a pH range between 5 and 8. The major fatty acids identified were C17:0 3-OH, iso-C15:0, and iso-C15:1 G. The DNA G + C content of strain Hal144T was 41.4 mol%. Based on the polyphasic approach, strain Hal144T represents a novel species of the genus Maribacter, and we propose the name Maribacter halichondriae sp. nov. The type strain is Hal144T (= DSM 114563T = LMG 32744T).

Comparison of functional performance outcomes between oral patented crystalline glucosamine sulfate and platelet-rich plasma among knee osteoarthritis patients: a propensity score matching analysis.

BACKGROUND: Among the medications used to treat knee osteoarthritis (OA), oral patented crystalline glucosamine sulfate (pCGS) and platelet-rich plasma (PRP) have become popular alternatives to painkillers or nonsteroidal anti-inflammatory drugs (NSAIDs). Although studies have shown that pCGS and PRP improve clinical outcomes, no study has compared outcomes between these optional treatments. We compared functional performance outcomes from baseline to the 1-year follow-up (FU) between oral pCGS and PRP in patients with knee OA. MATERIALS AND METHODS: Three hundred eighty-two patients receiving oral pCGS and 122 patients receiving PRP injections were enrolled for a review of functional performance outcomes, including a five-time sit-to-stand test (5xSST), time up-and-go test (TUGT), and 3-minute walk distance test (3MWDT). The patients were followed up for one year. The pCGS group received 1500 mg daily, whereas the PRP group received 2 cycles of intra-articular injections at week 0 and week 6. Using propensity score matching based on age, sex, height, weight, BMI, and Kellgren and Lawrence (KL) classification, all three functional performance outcomes were compared between the baseline (pretreatment), 6-week, 12-week, 24-week, and 1-year FUs. RESULTS: With a ratio of 2:1 (pCGS: PRP), 204 patients in the pCGS group were matched with 102 patients in the PRP group. Compared with the baseline levels, the PRP group showed significant improvements in 5xSST and TUGT outcomes from 6 weeks and significant improvements in 3MWDT outcomes from 12 weeks, whereas the pCGS group showed significant improvements in TUGT outcomes from 6 weeks and significant improvements in 5xSST and 3MWDT outcomes from 12 weeks. At the 24-week and 1-year FU, both groups showed significant improvements in all three functional performance tests without adverse events. CONCLUSIONS: Although the PRP group showed faster improvements in 5xSST outcomes at six weeks, from the 12-week to 1-year FU, both the pCGS and PRP groups showed significant improvements in 5xSST, TUGT, and 3MWDT outcomes. As the use of PRP is more complicated and invasive than the use of oral pCGS, the benefits and drawbacks of selecting PRP over pCGS in knee OA treatment should be examined.

Synthesis and Antifungal Activities of Glucosamine Aromatic Derivatives Against Four Phytopathogenic Fungi of Crops.

A series of diversified glucosamine derivatives (3a-3y) was synthesized and their antifungal activity was examined against four kinds of phytopathogens, Fusarium graminearum (F. graminearum), Fusarium moniliforme (F. moniliforme), Curvularia. lunata (C. lunata), and Rhizoctonia solani (R. solani) which cause seriously economic losses worldwide by affecting crops. The compound 3o showed remarkable antifungal activity against F. graminearum with EC50 value of 3.96 µg/mL, compared to the standard drug triadimefon (10.1 µg/mL). 3D-QSAR model with the statistically recommended values (r2=0.915, q2=0.872) showed that positive charge group or bulky group in the benzyl ring was favorable for the antifungal activity. Enzyme activity assays confirmed that 3o had a moderate inhibition of trehalase with inhibition rate of 51.4 % at 5 µg/mL, which is comparable to those of commercial inhibitor validamycin A with inhibition rate of 83.3 %. Molecular docking analysis revealed that 3o also had a hydrogen bond interaction with key amino acid residue compared to validoxylamine.

Can treatment with chondroitin and glucosamine sulphate prevent changes in the articular disc caused by temporomandibular joint osteoarthritis?

BACKGROUND: Chondroitin and glucosamine sulphates (CGS) are considered structure-modifying drugs and have been studied in the prevention, delay or reversal of structural morphological changes in joints caused by osteoarthritis. OBJECTIVE: The aim of the present study was to investigate the action of CGS on the progression of chemically induced osteoarthritis in the temporomandibular joint (TMJ) of rabbits by evaluating the serum levels of tumour necrosis factor (TNF-α) and collagen in the articular discs. MATERIALS AND METHODS: A sample of 36 male rabbits was divided into three groups: control (CG), osteoarthritis (OG) and treatment (TG). The disease was induced by intra-articular injection of sodium monoiodoacetate (10 mg/mL) in the OG and TG groups bilaterally. After 10 days, the TG animals received subcutaneous injection of chondroitin sulphates and glucosamine (7.5 mg/kg) and the OG and CG received saline solution (50 µL). Euthanasia times were subdivided into 40 and 100 days. Collagen quantification was performed by biochemical and histological analysis and for the quantification of serum levels of TNF-α, an enzyme immunoassay was used. RESULTS: The TG showed an increase in the collagen area of the articular disc when compared to the CG and the OG. The increase collagen concentration in the discs did not show a statistically significant difference between the groups. Post-treatment TNF-α levels were significantly lower in TG compared to OG. CONCLUSIONS: The results indicate that CGS treatment delayed the degeneration of the collagen in the TMJ articular disc and reduced serum TNF-α levels, indicating a preventive effect on OA progression.

Synthesis of Novel 3-Deoxy-3-thio Derivatives of d-Glucosamine and Their Application as Ligands for the Enantioselective Addition of Diethylzinc to Benzaldehyde.

A series of novel thio-derivatives of d-glucosamine has been synthesized using double inversion procedures at the C3 atom. New compounds were applied as ligands for the diethylzinc addition to benzaldehyde and the products of the addition were obtained with a low to good enantiomeric ratio. The direction and the level of the asymmetric induction were highly dependent on the type of protecting groups on the nitrogen and sulfur atoms.

Glucosamine Enhancement of Learning and Memory Functions by Promoting Fibroblast Growth Factor 21 Production.

Fibroblast growth factor 21 (FGF21) plays a crucial role in metabolism and brain function. Glucosamine (GLN) has been recognized for its diverse beneficial effects. This study aimed to elucidate the modulation of FGF21 production by GLN and its impact on learning and memory functions. Using both in vivo and in vitro models, we investigated the effects of GLN on mice fed with a normal diet or high-fat diet and on mouse HT22 hippocampal cells, STHdhQ7/Q7 striatal cells, and rat primary cortical neurons challenged with GLN. Our results indicated that GLN promotes learning and memory functions in mice and upregulates FGF21 expression in the hippocampus, cortex, and striatum, as well as in HT22 cells, STHdhQ7/Q7 cells, and cortical neurons. In animals receiving GLN together with an FGF21 receptor FGFR1 inhibitor (PD173074), the GLN-enhanced learning and memory functions and induction of FGF21 production in the hippocampus were significantly attenuated. While exploring the underlying molecular mechanisms, the potential involvement of NF-κB, Akt, p38, JNK, PKA, and PPARα in HT22 and NF-κB, Akt, p38, and PPARα in STHdhQ7/Q7 were noted; GLN was able to mediate the activation of p65, Akt, p38, and CREB in HT22 and p65, Akt, and p38 in STHdhQ7/Q7 cells. Our accumulated findings suggest that GLN may increase learning and memory functions by inducing FGF21 production in the brain. This induction appears to be mediated, at least in part, through GLN's activation of the NF-κB, Akt, p38, and PKA/CREB pathways.

Evaluation of efficacy and safety of glucosamine sulfate, chondroitin sulfate, and their combination regimen in the management of knee osteoarthritis: a systematic review and meta-analysis.

AIM: This study was aimed to assess the efficacy and safety of two oral Symptomatic Slow Acting Drugs for Osteoarthritis (SYSADOAs)-Glucosamine Sulfate, Chondroitin Sulfate, and their combination regimen in the management of knee osteoarthritis (KOA). METHODS: This systematic review was conducted according to PRISMA 2020 guidelines. A detailed literature search was performed from 03/1994 to 31/12/2022 using various electronic databases including PubMed, Embase, Cochrane Library, and Google Scholar, using the search terms-Glucosamine sulfate (GS), Chondroitin sulfate (CS), Knee osteoarthritis, Joint pain, Joint disease, and Joint structure, for literature concerning glucosamine, chondroitin, and their combination in knee osteoarthritis treatment. Cochrane Collaboration's Risk assessment tool (version 5.4.1) was used for assessing the risk of bias and the quality of the literature. The data was extracted from the included studies and subjected to statistical analysis to determine the beneficial effect of Glucosamine Sulfate, Chondroitin Sulfate, and their combination. RESULTS: Twenty-five randomized controlled trials (RCTs) were included in this systematic review. In short, exclusively 9 RCTs for GS, 13 RCTs for CS, and 3 RCTs for the combination of GS and CS. All these studies had their treatment groups compared with placebo. In the meta-analysis, CS showed a significant reduction in pain intensity, and improved physical function compared to the placebo; GS showed a significant reduction in tibiofemoral joint space narrowing. While the combination of GS and CS showed neither a reduction in pain intensity, nor any improvement in the physical function. However, the combination exhibited a non-significant reduction in joint space narrowing. In the safety evaluation, both CS and GS have shown good safety profile and were well tolerated. CONCLUSION: This meta-analysis revealed that the CS (with decreased pain intensity and improvement in the physical function), and GS (with significant reduction in the joint space narrowing) have significant therapeutic benefits. However, their combination did not significantly improve the symptoms or modify the disease. This may be due to the limited trials that are available on the combination of the sulfate forms of the intervention. Hence, there is a scope for conducting multicentric randomised controlled trials to evaluate and conclude the therapeutic role of CS and GS combination in the management of KOA.

D-Hexopyranosides with Vicinal Nitrogen-Containing Functionalities.

Various substituted D-hexopypyranosides units with nitrogen-containing functionalities are present in many important natural compounds and pharmaceutical substances. Since their complex structural diversity contributes to a broad spectrum of biological functions and activities, these derivatives are frequently studied. This review covers syntheses of D-hexopyranosides with vicinal nitrogen-containing functionalities since the 1960s, when the first articles emerged. The syntheses are arranged according to the positions of substitutions, to form a relative configuration of vicinal functionalities, and synthetic methodologies.

Synthesis of cyclic ß-1,6-oligosaccharides from glucosamine monomers by electrochemical polyglycosylation.

The synthesis of protected precursors of cyclic ß-1,6-oligoglucosamines from thioglycosides as monomers is performed by electrochemical polyglycosylation. The monomer with a 2,3-oxazolidinone protecting group afforded the cyclic disaccharide exclusively. Cyclic oligosaccharides up to the trisaccharide were obtained using the monomer with a 2-azido-2-deoxy group.

Inhibition of N-glycosylation by glucosamine hydrochloride inhibits TGF-ß1-induced LOXL2 secretion.

Kidney fibrosis is closely associated with the progression of chronic kidney disease (CKD). Furthermore, copper-containing secretory amine oxidases, such as lysyl oxidase (LOX) and LOX-like 1-4 (LOXL1-4), play pivotal roles in the regulation of extracellular components and facilitate fibrosis. In this study, we investigated the regulation of LOX enzymes in human tubular epithelial HK2 cells to help clarify the role of LOX enzymes in kidney fibrosis. Among 5 LOX enzymes, LOXL2 expression is abundantly expressed in HK2 cells. LOX enzymes inhibitor, ß-aminopropionitrile, suppressed transforming growth factor-ß1 (TGF-ß1)-promoted epithelial-to-mesenchymal transition processes in HK2 cells, indicating that LOX enzymes are involved in TGF-ß1-mediated fibrotic processes. Recent studies suggest that LOX enzymes are secreted into the extracellular spaces by exosomes and promote fibrotic processes. Similar to the previous reports, we observed that exosomes secreted from HK2 cells carry LOXL2 into the extracellular spaces. Furthermore, we determined that N-glycosylation on the asparagine residues plays a key role in LOXL2 secretion. Amino acid mutations in three asparagine residues, which can be glycosylated, suppressed the secretion of mutated LOXL2. Moreover, N-acetylglucosaminyltransferase 5, an enzyme used for the biosynthesis of ß1,6N-acetylglucosamine-branched N-glycans, participated in LOXL2 secretion, and the N-glycosylation inhibitor, glucosamine hydrochloride (GS), inhibited TGF-ß1-mediated LOXL2 secretion and fibrotic processes. Overall, TGF-ß1 promotes LOXL2 secretion and may participate in kidney fibrosis. Our results provide novel insight into the antifibrotic properties of GS that contribute to the inhibition of CKD progression.