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A pilot study of N-acetyl glucosamine, a nutritional substrate for glycosaminoglycan synthesis, in paediatric chronic inflammatory bowel disease
Abstract
The breakdown of glycosaminoglycans is an important consequence of inflammation at mucosal surfaces, and inhibition of metalloprotease activity may be effective in treating chronic inflammation.
To report an alternative approach, using the nutriceutical agent N-acetyl glucosamine (GlcNAc), an amino-sugar directly incorporated into glycosaminoglycans and glycoproteins, as a substrate for tissue repair mechanisms.
GlcNAc (total daily dose 3-6 g) was administered orally as adjunct therapy to 12 children with severe treatment-resistant inflammatory bowel disease (10 Crohn's disease, 2 ulcerative colitis). Seven of these children suffered from symptomatic strictures. In addition, similar doses were administered rectally as sole therapy in nine children with distal ulcerative colitis or proctitis resistant to steroids and antibiotics. Where pre- and post-treatment biopsies were available (nine cases), histochemical assessment of epithelial and matrix glycosaminoglycans and GlcNAc residues was made.
Eight of the children given oral GlcNAc showed clear improvement, while four required resection. Of the children with symptomatic Crohn's stricture, only 3 of 7 have required surgery over a mean follow-up of > 2.5 years, and endoscopic or radiological improvement was detected in the others. Rectal administration induced remission in two cases, clear improvement in three and no effect in two. In all cases biopsied there was evidence of histological improvement, and a significant increase in epithelial and lamina propria glycosaminoglycans and intracellular GlcNAc.
GlcNAc shows promise as an inexpensive and nontoxic treatment in chronic inflammatory bowel disease, with a mode of action which is distinct from conventional treatments. It may have the potential to be helpful in stricturing disease. However, controlled trials and an assessment of enteric-release preparations are required to confirm its efficacy and establish indications for use.
... Bovine colostrum contains abundant growth factors, including insulin-like and epidermal growth factors 28 , and demonstrates efficacy in ulcerative colitis 29,30 . N-acetyl glucosamine may restore the intestinal barrier since glycosylation is deficient in SAM 31,32 , and it has been shown to promote mucosal healing in inflammatory bowel disease (IBD) 33 . Teduglutide improves nutrient absorption through mucosal regeneration in intestinal failure 34,35 . ...
... All treatment courses were 14 days. Samples for endpoint analysis were collected on day 15 (permissible window [15][16][17][18][19]; children were then discharged if ready and reviewed on day 28 (window [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Blood samples for safety monitoring (full blood count, renal and liver function, phosphate) were collected at baseline, 5 and 15 days post-randomisation. ...
... 0.5-1 g colostrum/kg/day to examine gut immune priming 47 , and Barakat & Omar used 3 g/day of colostrum for children aged 6 months to 2 years suffering from acute diarrhoea 48 . The dose of N-acetyl glucosamine was based on our previous study in paediatric Crohn's disease, where daily dosage of 6 grams augmented expression of epithelial glycosaminoglycans without evidence of adverse effects 33 . Intravenous doses of up to 100 mg have been tolerated in adults without adverse effects 33 and breastfed newborns consume 650-1500 mg of n-acetyl glucosamine per litre of human breast milk from well-nourished mothers 49 . ...
Malnutrition underlies almost half of all child deaths globally. Severe Acute Malnutrition (SAM) carries unacceptable mortality, particularly if accompanied by infection or medical complications, including enteropathy. We evaluated four interventions for malnutrition enteropathy in a multi-centre phase II multi-arm trial in Zambia and Zimbabwe and completed in 2021. The purpose of this trial was to identify therapies which could be taken forward into phase III trials. Children of either sex were eligible for inclusion if aged 6–59 months and hospitalised with SAM (using WHO definitions: WLZ <−3, and/or MUAC <11.5 cm, and/or bilateral pedal oedema), with written, informed consent from the primary caregiver. We randomised 125 children hospitalised with complicated SAM to 14 days treatment with (i) bovine colostrum (n = 25), (ii) N-acetyl glucosamine (n = 24), (iii) subcutaneous teduglutide (n = 26), (iv) budesonide (n = 25) or (v) standard care only (n = 25). The primary endpoint was a composite of faecal biomarkers (myeloperoxidase, neopterin, α1-antitrypsin). Laboratory assessments, but not treatments, were blinded. Per-protocol analysis used ANCOVA, adjusted for baseline biomarker value, sex, oedema, HIV status, diarrhoea, weight-for-length Z-score, and study site, with pre-specified significance of P < 0.10. Of 143 children screened, 125 were randomised. Teduglutide reduced the primary endpoint of biomarkers of mucosal damage (effect size −0.89 (90% CI: −1.69,−0.10) P = 0.07), while colostrum (−0.58 (−1.4, 0.23) P = 0.24), N-acetyl glucosamine (−0.20 (−1.01, 0.60) P = 0.67), and budesonide (−0.50 (−1.33, 0.33) P = 0.32) had no significant effect. All interventions proved safe. This work suggests that treatment of enteropathy may be beneficial in children with complicated malnutrition. The trial was registered at ClinicalTrials.gov with the identifier NCT03716115.
... It is an important precursor to glycoproteins and GAG, such as hyaluronic acid, heparan sulfate, and keratan sulfate (Jerosch, 2011). Besides their chondroprotective and chondrostimulating role, GAG may increase epithelial defenses, contributing to intestinal integrity (Salvatore et al., 2000;Hori et al., 2001;Segarra et al., 2016) and mucin biosynthesis (Salvatore et al., 2000) in dogs, humans, and mice. ...
... It is an important precursor to glycoproteins and GAG, such as hyaluronic acid, heparan sulfate, and keratan sulfate (Jerosch, 2011). Besides their chondroprotective and chondrostimulating role, GAG may increase epithelial defenses, contributing to intestinal integrity (Salvatore et al., 2000;Hori et al., 2001;Segarra et al., 2016) and mucin biosynthesis (Salvatore et al., 2000) in dogs, humans, and mice. ...
... A longer villi in the jejunum of broilers fed diet supplemented with glucosamine sulfate may be related to the ability of this nutraceutical to increase epithelial defenses, which contributes to intestinal integrity and histomorphometry, as observed in humans (Salvatore et al., 2000). According to Liu et al. (2012), glucosamine may promote stabilization of intestinal mucosa barrier, which reduces penetration of intestinal endotoxins, food metabolites, and bacteria. ...
We aimed to evaluate the performance, nutrient digestibility, and intestinal histomorphometry of broilers fed diet supplemented with chondroitin sulfate and glucosamine sulfate. The experiment was carried out with 320 male broiler chicks distributed in a completely randomized design in a 2×2 factorial scheme (0 and 0.1% chondroitin sulfate and 0 and 0.3% glucosamine sulfate), with eight replications of 10 birds. Performance was evaluated at 7 and 21 days of age, nutrient digestibility of the diet was performed from 18 to 21 days of age, and small intestine histomorphometry was evaluated at 21 days of age. Broilers fed diet supplemented with 0.3% glucosamine sulfate showed high final weight and weight gain. A significant interaction was observed between sulfates for digestibility coefficients of nitrogen, mineral matter, and calcium. The use of 0.1% chondroitin sulfate without glucosamine sulfate resulted in a reduced digestibility of nitrogen but increased digestibility of total minerals and calcium. Diets without chondroitin sulfate with 0.3% glucosamine sulfate increased the digestibility coefficients of mineral matter and calcium. A significant interaction was found for jejunum villus height, which was higher in broilers fed diet supplemented with 0.3% glucosamine sulfate, regardless of the inclusion of chondroitin sulfate. Thus, supplementation with glucosamine sulfate in broiler diets contributes to high weight gain and villus height. Sulfates used in isolation promote high digestibility of minerals.
... Its administration has been shown to induce disease remission in a pilot study in paediatric IBD cases. 21 ...
... N-acetylglucosamine (NAG), a naturally occurring amino sugar which can be used as a precursor for epithelial glycosaminoglycan synthesis, was associated with an increase in the growth factor-containing principal component by day 15. As a sugar which is depleted in patients with IBD, 29 NAG can improve IBD symptoms in children 21 and inhibits inflammation and neurogeneration in adults with multiple sclerosis, 30 through controlling the N-linked glycans in cells which subsequently help to suppress T-helper-1 cells. This nutraceutical product, along with budesonide, is one of the cheapest and easiest to administer, as the product can be kept at room temperature and is given orally. ...
Background
Severe acute malnutrition (SAM) is the most life-threatening form of undernutrition, and children hospitalised with complications have unacceptably high mortality. Complicated SAM is a multisystem disease characterised pathophysiologically by muscle wasting, systemic inflammation, metabolic dysfunction, and malnutrition enteropathy including epithelial barrier dysfunction. There is a clear need for novel interventions to address the underlying pathogenic perturbations of complicated SAM.
Methods
In this analysis of tertiary outcomes from a phase II multi-centre trial in Zambia and Zimbabwe, multiplex biomarkers were measured in 122 children (57% male) with SAM randomised following stabilisation (‘baseline’) to one of four interventions for 14 days to treat malnutrition enteropathy: budesonide, N-acetylglucosamine, colostrum, or teduglutide, compared with standard-of-care. Following measurement of 35 biomarkers from day 15 plasma samples using Luminex and ELISA, the dimensionality of biomarker data was reduced using principal component analysis.
Findings
Both budesonide and colostrum reduced systemic inflammation (as measured by CD14, IL1-ra, CRP, and LBP), while children receiving colostrum had higher GLP2 and angiopoietin, and lower circulating lipopolysaccharide, suggesting better restoration of epithelial barrier function. N-acetylglucosamine, a precursor for epithelial glycosaminoglycan synthesis, increased biomarkers of epithelial regeneration (EGF, VEGF), and circulating growth factors (angiopoietin, IGFBP-3, and GCSF).
Interpretation
Interventions aimed at ameliorating malnutrition enteropathy showed plausible effects on biomarkers of inflammation and epithelial regeneration, demonstrating an interdependence of systemic inflammation and enteropathy markers seen in structural analysis. Given the interplay between inflammation and tissue restoration in malnutrition, this mechanism of action supports larger trials to determine the clinical benefits of interventions, either alone or in combination, in children with complicated SAM.
Funding
This analysis of tertiary outcomes for the TAME trial was funded by a 10.13039/100010269Wellcome grant to JPS (220566/Z/20/Z). The TAME trial was funded by a grant from the 10.13039/501100000265Medical Research Council (UK), number MR/P024033/1. AJP is funded by 10.13039/100010269Wellcome (108065/Z/15/Z). Takeda UK provided teduglutide at a discounted price.
... For example, a significant decrease in glucose, galactose, and mannose was described under rising temperature-stress conditions (Lee et al., 2016). Thus, mannose, glucose, and galactose can serve as markers for temperature stress, while N-acetyl glucosamine exhibits antiinflammatory properties and reduces the production of free radicals (Salvatore et al., 2000). ...
... For example, a significant decrease in glucose, galactose, and mannose was described under rising temperature-stress conditions (Lee et al. 2016). Thus, mannose, glucose, and galactose can serve as markers for temperature stress, while N-acetyl glucosamine exhibits anti-inflammatory properties and reduces the production of free radicals (Salvatore et al. 2000). N-acetyl galactosamine also helps in the O-glycosylation of coral mucin molecules. ...
Declaration As required under the Goa University Ordinance OA-19A, I state that the present thesis entitled "Characterization of coral mucus for its microbes and antimicrobial properties under healthy and stress conditions" is my original contribution and that the same has not been submitted on any previous occasion for any degree. To the best of my knowledge, the present study is the first comprehensive work of its kind from the area mentioned. The literature related to the problem investigated has been cited. Due acknowledgments have been made, wherever facilities and suggestions have been availed.
... 3,36 Glycan-targeting therapy also capitalizes on favorable safety and efficacy data of GlcNAc supplementation in patients with inflammatory bowel disease and other immune-mediated disorders, like multiple sclerosis. [37][38][39][40] To test in vivo, we supplemented Zip8 +/+ , Zip8 +/393T and Zip8 393T/393T with GlcNAc 0.25 mg/ml in drinking water for 7 days and studied the change in N-glycosylation of the ileal epithelial compartment by lectin immunofluorescence (Fig. 4A,B,C). The GlcNAc-treated Zip8 +/393T and Zip8 393T/393T animals show enhanced L-PHA staining, consistent with increased tri-and tetraantennary N-glycan branching of the ileal epithelial cells and along the epithelial brush border with a reciprocal decrease in sWGA staining compared to sham. ...
... 13,[69][70][71][72] GlcNAc supplementation builds from prior studies in animal models and patients with IBD showing safety and therapeutic benefit, as well as more recent studies in the treatment of patients with multiple sclerosis, with immune-mediated effects of enhancing N-glycan branching on effector T cells. 1,[38][39][40]73 By lectin staining, physiologic measurements of bile acid homeostasis and intestinal permeability, and DSS challenge (tested only in Zip8 393T/393T mice), the effect of GlcNAc supplementation was most significant in Zip8 +/393T and Zip8 393T/393T mice with minimal effects on Zip8 +/+ animals. These data support a specific benefit in ZIP8 391-Thr carriers, but the prior studies suggest that benefit from glycan-targeting therapy may extend to patients with other drivers of aberrant N-glycosylation and aligns with our data demonstrating consistent down-regulation of mRNA expression of glycosyltransferases and increased abundance of truncated N-glycans associated with Crohn's disease compared to healthy individuals. ...
The treatment of defective glycosylation in clinical practice has been limited to patients with rare and severe phenotypes associated with congenital disorders of glycosylation (CDG). Carried by approximately 5% of the human population, the discovery of the highly pleiotropic, missense mutation in a manganese transporter ZIP8 has exposed under-appreciated roles for Mn homeostasis and aberrant Mn-dependent glycosyltransferases activity leading to defective N-glycosylation in complex human diseases. Here, we test the hypothesis that aberrant N-glycosylation contributes to disease pathogenesis of ZIP8 A391T-associated Crohns disease. Analysis of N-glycan branching in intestinal biopsies demonstrates perturbation in active Crohns disease and a genotype-dependent effect characterized by increased truncated N-glycans. A mouse model of ZIP8 391-Thr recapitulates the intestinal glycophenotype of patients carrying mutations in ZIP8. Borrowing from therapeutic strategies employed in the treatment of patients with CDGs, oral monosaccharide therapy with N-acetylglucosamine ameliorates the epithelial N-glycan defect, bile acid dyshomeostasis, intestinal permeability, and susceptibility to chemical-induced colitis in a mouse model of ZIP8 391-Thr. Together, these data support ZIP8 391-Thr alters N-glycosylation to contribute to disease pathogenesis, challenging the clinical paradigm that CDGs are limited to patients with rare diseases. Critically, the defect in glycosylation can be targeted with monosaccharide supplementation, providing an opportunity for genotype-driven, personalized medicine.
... Accordingly, F. prausnitzii encodes pectinolytic enzymes [107]. F. prausnitzii strains can utilize the glycoprotein N-acetylglucosamine [97] found in gut mucosa [98]. Treatment with N-acetylglucosamine heals inflamed and damaged soft tissues of the gut [98], and restores gut function to improve Crohn's disease (CD). ...
... F. prausnitzii strains can utilize the glycoprotein N-acetylglucosamine [97] found in gut mucosa [98]. Treatment with N-acetylglucosamine heals inflamed and damaged soft tissues of the gut [98], and restores gut function to improve Crohn's disease (CD). Mucin stimulates growth of the beneficial bacteria F. prausnitzii [99], since F. prausnitzii isolates cannot utilize mucin or mucopolysaccharides [97]. ...
Simple Summary
Hepatocellular carcinoma (HCC) remains one of the more incurable diseases. Thus, finding an HCC treatment is urgent for this unmet medical need. Immunotherapy is a break-through treatment that may help 15–20% of HCC patients. In this review, pharmacological and immune-therapeutical targeting of druggable cancer drivers, immune checkpoints, and long non-coding RNAs for HCC and cholangiocarcinoma are discussed.
Abstract
Cancer contains tumor-initiating stem-like cells (TICs) that are resistant to therapies. Hepatocellular carcinoma (HCC) incidence has increased twice over the past few decades, while the incidence of other cancer types has trended downward globally. Therefore, an understanding of HCC development and therapy resistance mechanisms is needed for this incurable malignancy. This review article describes links between immunotherapies and microbiota in tumor-initiating stem-like cells (TICs), which have stem cell characteristics with self-renewal ability and express pluripotency transcription factors such as NANOG, SOX2, and OCT4. This review discusses (1) how immunotherapies fail and (2) how gut dysbiosis inhibits immunotherapy efficacy. Gut dysbiosis promotes resistance to immunotherapies by breaking gut immune tolerance and activating suppressor immune cells. Unfortunately, this leads to incurable recurrence/metastasis development. Personalized medicine approaches targeting these mechanisms of TIC/metastasis-initiating cells are emerging targets for HCC immunotherapy and microbiota modulation therapy.
... In principle, the immediate consequence of PGM3 loss is reduced UDP-GlcNAc biosynthesis with downstream glycosylation defects underlying the associated consequences. Oral administration of GlcNAc has been shown to significantly increase the UDP-GlcNAc pool, glycoprotein production, and clinical improvement in pediatric inflammatory bowel disease (34,35). Therefore, exploring the effects of GlcNAc treatment on PGM3 insufficiency may provide a promising and inexpensive strategy to correct metabolic deficiencies. ...
Background
Hypomorphic mutations in the phosphoacetylglucosamine mutase 3 (PGM3) gene cause a glycosylation disorder that leads to immunodeficiency. It is often associated with recurrent infections and atopy. The exact etiology of this condition remains unclear.
Objective
This study aimed to characterize the phenotypes and immunological features associated with PGM3 insufficiency and investigate potential disease mechanisms.
Methods
A systematic review of 44 published cases of PGM3 variants was performed, followed by T-cell phenotyping of two patients with PGM3 variants. A genotype-phenotypic severity study was conducted by comparing the residual PGM3 expression of the 12 reconstituted variants in human B cells. A PGM3 inhibitor was used to assess its effect on CD4+ T cell proliferation and differentiation.
Results
Patients with PGM3 variants frequently presented with recurrent infections and atopy, accompanied by reduced naïve CD4+ T cell counts. A genotype–phenotype study showed that low levels of residual PGM3 expression are correlated with disease severity. Notably, inhibition of PGM3 activity impaired TCR-mediated CD4+ T cell proliferation and the synthesis of UDP-GlcNAc, complex N-glycans, O-GlcNAc, glycolytic stress, and mitochondrial respiration during proliferation in a dose-dependent manner. Partial loss of PGM3 activity was observed to preferentially enhance Th1 and Th2 differentiation, while attenuating Th17 and Treg differentiation, consistent with clinical observations.
Conclusion
PGM3 is a critical regulator of CD4+ T-cell proliferation and differentiation. These findings provide new insights into the diverse clinical manifestations and therapeutic development of PGM3 deficiency.
... In addition, an animal study showed that oral supplementation with GlcNAc enhanced intestinal barrier function and protected against chemically-induced colitis (39). A pilot clinical study that tested oral administration of GlcNAc in children with treatmentresistant inflammatory bowel disease showed promising results in improvement of symptoms (40). These results suggest that GlcNAc itself may influence barrier function and inflammation in the intestine. ...
Human milk oligosaccharides (HMOs) are a diverse group of structures and an abundant bioactive component of breastmilk that contribute to infant health and development. Preclinical studies indicate roles for HMOs in shaping the infant gut microbiota, inhibiting pathogens, modulating the immune system, and influencing cognitive development. In the past decade, several industrially produced HMOs have become available to fortify infant formula. Clinical intervention trials with manufactured HMOs have begun to corroborate some of the physiological effects reported in preclinical studies, especially modulation of the gut microbiota in the direction of breastfed infants. As more HMOs become commercially available and as HMOs have some shared mechanisms of action, there is a need to better understand the unique and differential effects of individual HMOs and the benefits of combining multiple HMOs. This review focuses on the differential effects of different HMO structural classes and individual structures and presents a scientific rationale for why combining multiple structurally diverse HMOs is expected to exert greater biological effects.
... Remarkably, a preliminary investigation into the oral administration of GlcNAc in pediatric IBD unveiled its potential as a potent therapeutic agent. Over half of the children receiving GlcNAc treatment experienced clinical remission along with histological improvement in terms of promoting intestinal lining of the mucosa [129]. In addition, oral gavage of mice with chito-oligosaccharides (COS), short chains of repeating units of N-GlcNAc, resulted in decreased colonic inflammation and reduced activation of inflammatory cells with lower levels of pro-inflammatory cytokines (TNF-α and IL-6) [130]. ...
... We have previously shown that GlcNAc limits T cell activation/growth and when provided orally to mice, inhibits experimental autoimmune encephalomyelitis, a mouse model of Multiple Sclerosis (MS), as well as autoimmune diabetes in the Non Obese Diabetic mouse model . GlcNAc has also been given orally (3-6 g/day) to children with refractory inflammatory bowel disease for~2 years, with 8 of 12 showing clinical improvement without reported toxicities and/or side effects (Salvatore et al., 2000). We have recently observed that serum levels of endogenous GlcNAc are markedly reduced in patients with the progressive form of MS and correlate with clinical disability and imaging measures of neurodegeneration (Alexander Brandt and Michael Demetriou, unpublished data). ...
Rapidly proliferating cells switch from oxidative phosphorylation to aerobic glycolysis plus glutaminolysis, markedly increasing glucose and glutamine catabolism. Although Otto Warburg first described aerobic glycolysis in cancer cells >90 years ago, the primary purpose of this metabolic switch remains controversial. The hexosamine biosynthetic pathway requires glucose and glutamine for de novo synthesis of UDP-GlcNAc, a sugar-nucleotide that inhibits receptor endocytosis and signaling by promoting N-acetylglucosamine branching of Asn (N)-linked glycans. Here, we report that aerobic glycolysis and glutaminolysis cooperatively reduce UDP-GlcNAc biosynthesis and N-glycan branching in mouse T cell blasts by starving the hexosamine pathway of glucose and glutamine. This drives growth and pro-inflammatory T H 17 over anti-inflammatory-induced T regulatory (iTreg) differentiation, the latter by promoting endocytic loss of IL-2 receptor-a (CD25). Thus, a primary function of aerobic glycolysis and glutaminolysis is to cooperatively limit metabolite supply to N-glycan biosynthesis, an activity with widespread implications for autoimmunity and cancer.
... 46 This suggested that glucosamine could potentially serve as a new functional food for individuals with IBD and may help in managing stricturing disease. 47 Considering clopidogrel, it potentially inhibits the inflammatory factors in IBD and alleviates IBD symptoms. Earlier research indicated that clopidogrel enhanced the inhibition of platelet activation, platelet-leukocyte interaction, and P-selectin expression on CD40 lymphocytes through P2Y12 receptor inhibition, which might contribute to the resolution of IBD symptoms. ...
Aim: Drug repurposing, utilizing electronic healthcare records (EHRs), offers a promising alternative by repurposing existing drugs for new therapeutic indications, especially for patients lacking effective therapies. Intestinal fibrosis, a severe complication of Crohn's disease (CD), poses significant challenges, increasing morbidity and mortality without available pharmacological treatments. This article focuses on identifying medications associated with an elevated or reduced risk of fibrosis in CD patients through a population-wide real-world data and artificial intelligence (AI) approach.
Methods: Patients aged 65 or older with a diagnosis of CD from 1996 to 2019 in the Danish EHRs were followed for up to 24 years. The primary outcome was the need of specific surgical procedures, namely proctocolectomy with ileostomy and ileocecal resection as proxies of intestinal fibrosis. The study explored drugs linked to an increased or reduced risk of the study outcome through machine-learning driven survival analysis.
Results: Among the 9,179 CD patients, 1,029 (11.2%) underwent surgery, primarily men (58.5%), with a mean age of 76 years, 10 drugs were linked to an elevated risk of surgery for proctocolectomy with ileostomy and ileocecal resection. In contrast, 10 drugs were associated with a reduced risk of undergoing surgery for these conditions.
Conclusion: This study focuses on repurposing existing drugs to prevent surgery related to intestinal fibrosis in CD patients, using Danish EHRs and advanced statistical methods. The findings offer valuable insights into potential treatments for this condition, addressing a critical unmet medical need. Further research and clinical trials are warranted to validate the effectiveness of these repurposed drugs in preventing surgery related to intestinal fibrosis in CD patients.
... For example, a significant decrease in glucose, galactose, and mannose was described under rising temperature-stress conditions (Lee et al. 2016). Thus, mannose, glucose, and galactose can serve as markers for temperature stress, while N-acetyl glucosamine exhibits anti-inflammatory properties and reduces the production of free radicals (Salvatore et al. 2000). N-acetyl galactosamine also helps in the O-glycosylation of coral mucin molecules. ...
Coral mucus secreted by mucocytes provides a protective physicochemical and physiological barrier between coral tissue and external environmental threats. The biomolecules and nutrients of the secreted mucus are derived from endosymbionts, coral polyps and support coral functions, such as feeding, sediment clearing and protection, against numerous biotic and abiotic stressors. The surface mucus layer also houses a diverse community of beneficial microorganisms that defend against pathogens. Enzymes including peptidases, esterases, and glycosidases were observed and described in mucus. Most importantly, the presence of phenoloxidase, an intracellular enzyme in secretory mucus, generally triggers melanin synthesis, providing fast-acting components of invertebrate immunity in disease resistance. However, the purpose and the mechanism of mucus release, effects of mucus components on defense properties, and functional roles in intra- and interspecific interactions are not well described. Thus, the present review aims to understand the mucus components and the complex roles played by mucus in microbial associations, feeding, and resilience that influence coral health.
... Glucosamine hydrochloride is a natural constituent of glycoproteins mainly found in connective tissues and gastrointestinal mucosal membranes. Therefore, it is considered an effective therapeutic agent for treating osteoarthritis, 14 gastritis, and inflammatory bowel diseases, 15 as well as lung injury. 16 Glucosamine is found to be a major constituent of brain glycogen, in addition, it has a protective effect against brain damage, 4,17 but its role in managing depression-like effect has not been established yet. ...
Radiotherapy is a very important tool in the treatment of cancer; nevertheless, its side effects are a hindrance to its use. The present study is designed to evaluate glucosamine effects against radiation-induced brain oxidative stress and depression-like effect in rats. Four groups of female Wister rats were used as control, irradiated (4 × 2 Gy), glucosamine (1 g/kg P.O), and glucosamine + irradiated group. The behavioral responses are estimated. The brain hippocampi of the rats are separated to evaluate oxidative stress biochemical parameters and glycogen synthase kinase pathway in addition to the biogenic amines. Irradiation exposure led to disturbances in the behavioral assessments (forced swimming test, light-dark box, and open field test) and a significant decrease in brain GSH, neurotransmitters (serotonin, norepinephrine, and dopamine), phosphatidyli-nositol 3 kinase (PI3K), and phosphorylated protein kinase-B (p-AKT) levels. Additionally, MDA and ROS levels increased significantly post-irradiation along with the phosphorylated glycogen synthase kinase (p-GSK3). Glucosamine administration before irradiation caused improvement in the behavioral valuations and the biochemical parameters in the brain as well. Glucosamine might be used as a radioprotector to improve brain function and as an antidepressant drug. It could be promising as a future therapy in managing depression occurring during radiotherapy.
... GlcNAc has great potential in the treatment of gastritis and inflammatory bowel disease, 55,56 damaged cartilage, 35 rheumatoid arthritis, and cancer. 49 However, these conclusions were all based on the exogenous administration of GlcNAc and were unrelated to the gut microbiota. ...
Microbiota are known to modulate the host response to influenza infection, but the mechanisms remain largely unknown. Gut metabolites are the key mediators through which gut microbes play anti-influenza effect. Transferring fecal metabolites from mice with high influenza resistance into antibiotic-treated recipient mice conferred resistance to influenza infections. By comparing the metabolites of different individuals with high or low influenza resistance, we identified and validated N-acetyl-D-glucosamine (GlcNAc) and adenosine showed strong positive correlations with influenza resistance and exerted anti-influenza effects in vivo or in vitro, respectively. Especially, GlcNAc mediated the anti-influenza effect by increasing the proportion and activity of NK cells. Several gut microbes, including Clostridium sp., Phocaeicola sartorii, and Akkermansia muciniphila, were positively correlated with influenza resistance, and can upregulate the level of GlcNAc in the mouse gut by exogenous supplementation. Subsequent studies confirmed that administering a combination of the three bacteria to mice via gavage resulted in similar modulation of NK cell responses as observed with GlcNAc. This study demonstrates that gut microbe-produced GlcNAc protects the host against influenza by regulating NK cells, facilitating the elucidation of the action mechanism of gut microbes mediating host influenza resistance.
... Earlier studies have shown that intravenous doses of GlcNAc in humans that are ~ 2-8 times higher (20 g, 100 g) than examined here lacked toxicity, including no alterations in blood glucose or insulin [62,63]. Oral GlcNAc (3-6 g/ day) has also been used in 12 children with inflammatory bowel disease for ~ 2 years without reported toxicities [64]. In rats, chronic systematic toxicological studies at doses of 2323-2545 mg/kg/day for 114 weeks found no toxicity [65,66]. ...
Background
In the demyelinating disease multiple sclerosis (MS), chronic-active brain inflammation, remyelination failure and neurodegeneration remain major issues despite immunotherapy. While B cell depletion and blockade/sequestration of T and B cells potently reduces episodic relapses, they act peripherally to allow persistence of chronic-active brain inflammation and progressive neurological dysfunction. N-acetyglucosamine (GlcNAc) is a triple modulator of inflammation, myelination and neurodegeneration. GlcNAc promotes biosynthesis of Asn (N)-linked-glycans, which interact with galectins to co-regulate the clustering/signaling/endocytosis of multiple glycoproteins simultaneously. In mice, GlcNAc crosses the blood brain barrier to raise N-glycan branching, suppress inflammatory demyelination by T and B cells and trigger stem/progenitor cell mediated myelin repair. MS clinical severity, demyelination lesion size and neurodegeneration inversely associate with a marker of endogenous GlcNAc, while in healthy humans, age-associated increases in endogenous GlcNAc promote T cell senescence.
Objectives and methods
An open label dose-escalation mechanistic trial of oral GlcNAc at 6 g ( n = 18) and 12 g ( n = 16) for 4 weeks was performed in MS patients on glatiramer acetate and not in relapse from March 2016 to December 2019 to assess changes in serum GlcNAc, lymphocyte N-glycosylation and inflammatory markers. Post-hoc analysis examined changes in serum neurofilament light chain (sNfL) as well as neurological disability via the Expanded Disability Status Scale (EDSS).
Results
Prior to GlcNAc therapy, high serum levels of the inflammatory cytokines IFNγ, IL-17 and IL-6 associated with reduced baseline levels of a marker of endogenous serum GlcNAc. Oral GlcNAc therapy was safe, raised serum levels and modulated N-glycan branching in lymphocytes. Glatiramer acetate reduces T H 1, T H 17 and B cell activity as well as sNfL, yet the addition of oral GlcNAc dose-dependently lowered serum IFNγ, IL-17, IL-6 and NfL. Oral GlcANc also dose-dependently reduced serum levels of the anti-inflammatory cytokine IL-10, which is increased in the brain of MS patients. 30% of treated patients displayed confirmed improvement in neurological disability, with an average EDSS score decrease of 0.52 points.
Conclusions
Oral GlcNAc inhibits inflammation and neurodegeneration markers in MS patients despite concurrent immunomodulation by glatiramer acetate. Blinded studies are required to investigate GlcNAc’s potential to control residual brain inflammation, myelin repair and neurodegeneration in MS.
... 13 A previous study showed that 3-6 g d −1 of NAG supplementation improved IBD symptoms in children with treatment-resistant IBD. 14 Recent studies have reported that the supply of NAG increases the expression of genes involved in the synthesis of mucin-type oligosaccharides as well as the thickness of the mucus layer in an aged mouse model. 15 In another study, O-linked-N-acetylglucosaminylation (O-GlcNAcylation), which is characterized by a β-glycosidic bond between the residues of NAG, serine, and threonine, was found to strengthen the intestinal barrier and maintain intestinal homeostasis. ...
Ulcerative colitis (UC) is a chronic gastrointestinal disease whose incidence is increasing rapidly worldwide. Anti-inflammatory medications, including 5-aminosalicylic acid (5-ASA), corticosteroids, and immunosuppressants, are used for its treatment; however, new alternatives would be required due to the serious side effects of some of these medications. N-Acetylglucosamine (NAG) is an amino sugar composed of mucin that is secreted by intestinal epithelial cells. It is also used to promote the growth of intestinal bacteria. The current study aimed to determine the efficacy of NAG against dextran sulfate sodium (DSS)-induced chronic colitis and elucidate its mechanism of action. Mice were randomly divided into control, DSS, 0.1% sulfasalazine, 0.1% NAG, 0.3% NAG, and 0.3% NAG-dimer (NAG-D) groups, and results showed that colitis-induced body weight loss, disease activity, colonic tissue damage, colon length shortening, and the loss of mucin-secreting area were significantly improved in the NAG-D group. The intestinal permeability indicator, serum CD 14 level, and expression of the tight junction protein, occludin, were both improved in the 0.3% NAG group. Inflammatory biomarkers, including GATA3, IFN-γ, p-IκBα, COX2, TGF-β1, and Smad7, were significantly lower in the 0.3% NAG and NAG-D groups than in the DSS group. The intestinal microbial composition was most significantly altered in the 0.3% NAG group, showing decreased ratios of pathogenic bacteria, such as Betaproteobacteria, especially Burkholderiales. The results overall suggested that NAG or NAG-D supplementation can alleviate inflammation by strengthening the intestinal barrier function and maintaining gut microbiota homeostasis in a DSS-induced colitis mouse model.
... According to the outcomes of these administrations, GlcN and its derivatives greatly improve the protection from joint damage [34][35][36][37]. GlcNAc has also been shown to be a promising inexpensive and non-toxic treatment in inflammatory bowel disease such as ulcerative colitis and Crohn's disease [38]. Other studies have highlighted the role played by this substance against multiple sclerosis and other autoimmune diseases [39][40][41]. ...
Viral respiratory tract infections (RTIs) are responsible for significant morbidity and mortality worldwide. A prominent feature of severe respiratory infections, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is the cytokine release syndrome. Therefore, there is an urgent need to develop different approaches both against viral replication and against the consequent inflammation. N-acetylglucosamine (GlcNAc), a glucosamine (GlcN) derivative, has been developed as an immunomodulatory and anti-inflammatory inexpensive and non-toxic drug for non-communicable disease treatment and/or prevention. Recent studies have suggested that GlcN, due to its anti-inflammatory activity, could be potentially useful for the control of respiratory virus infections. Our present study aimed to evaluate in two different immortalized cell lines whether GlcNAc could inhibit or reduce both viral infectivity and the inflammatory response to viral infection. Two different viruses, frequent cause of upper and lower respiratory tract infections, were used: the H1N1 Influenza A virus (IAV) (as model of enveloped RNA virus) and the Human adenovirus type 2 (Adv) (as model of naked DNA virus). Two forms of GlcNAc have been considered, bulk GlcNAc and GlcNAc in nanoform to overcome the possible pharmacokinetic limitations of GlcNAc. Our study suggests that GlcNAc restricts IAV replication but not Adv infection, whereas nano-GlcNAc inhibits both viruses. Moreover, GlcNAc and mainly its nanoformulation were able to reduce the pro-inflammatory cytokine secretion stimulated by viral infection. The correlation between inflammatory and infection inhibition is discussed.
... Furthermore, the nanoparticles decreased signs related to colitis and facilitated mucosa healing (Xiao et al., 2017). One of the other attractive features of hyaluronic acid is that after breakdown, N-acetylglucosamine and Glucuronic acid act as building blocks for glycosaminoglycan synthesis and so accelerate bowel regeneration (Salvatore et al., 2000;Lee et al., 2020). ...
Inflammatory bowel disease (IBD) is a gastrointestinal disorder, affecting about several million people worldwide. Current treatments fail to adequately control some clinical symptoms in IBD patients, which can adversely impact the patient’s quality of life. Hence, the development of new treatments for IBD is needed. Due to their unique properties such as biocompatibility and sustained release of a drug, biomaterials-based drug delivery systems can be regarded as promising candidates for IBD treatment. It is noteworthy that considering the pathophysiological changes occurred in the gastrointestinal tract of IBD patients, especially changes in pH, surface charge, the concentration of reactive oxygen species, and the expression of some biomolecules at the inflamed colon, can help in the rational design of biomaterials-based drug delivery systems for efficient management of IBD. Here, we discuss about targeting these pathophysiological changes using biomaterials-based drug delivery systems, which can provide important clues to establish a strategic roadmap for future studies.
... Patients recovering from an exacerbation of ulcerative/membranous colitis display increased levels of glucosamine synthetase. This enzyme synthesizes N-acetyl-glucosamine (NAG), which was recently implicated in the tissue regeneration phase in pediatric IBD [26][27][28]. In addition, glucosamine and/or chondroitin are used as dietary supplements to reduce colonrectal cancer risk and systemic inflammation [29][30][31][32]. ...
Similar to canine inflammatory enteropathy, inflammatory bowel disease (IBD) is a chronic idiopathic condition characterized by remission periods and recurrent flares in which diarrhea, visceral pain, rectal bleeding/bloody stools, and weight loss are the main clinical symptoms. Intestinal barrier function alterations often persist in the remission phase of the disease without ongoing inflammatory processes. However, current therapies include mainly anti-inflammatory compounds that fail to promote functional symptoms-free disease remission, urging new drug discoveries to handle patients during this step of the disease. ALIAmides (ALIA, autacoid local injury antagonism) are bioactive fatty acid amides that recently gained attention because of their involvement in the control of inflammatory response, prompting the use of these molecules as plausible therapeutic strategies in the treatment of several chronic inflammatory conditions. N-palmitoyl-D-glucosamine (PGA), an under-researched ALIAmide, resulted in being safe and effective in preclinical models of inflammation and pain, suggesting its potential engagement in the treatment of IBD. In our study, we demonstrated that micronized PGA significantly and dose-dependently reduces colitis severity, improves intestinal mucosa integrity by increasing the tight junction proteins expression, and downregulates the TLR-4/NLRP3/iNOS pathway via PPAR-α receptors signaling in DNBS-treated mice. The possibility of clinically exploiting micronized PGA as support for the treatment and prevention of inflammation-related changes in IBD patients would represent an innovative, effective, and safe strategy.
... They are also available over the counter as a nutritional supplement, as well as a drug for treatment of osteoarthritis 94 and inflammatory bowel disease. 95 Rivlin et al. also pointed out that high oral doses (5-15 g/kg p.o.) are well tolerated in humans and that concentrations over 10 mM can be produced a few hours after oral administration, with a half-life of many hours. 89,96,101 This long time window and the fact that neither D-GlcN nor GlcNAc show significant effects on blood insulin and glucose levels 97 make them very suitable even for diabetic populations. ...
The ability of CEST MRI to detect the presence of millimolar concentrations of non‐metallic contrast agents has made it possible to study, noninvasively, important biological molecules such as proteins and sugars, as well as drugs already approved for clinical use. Here, we review efforts to use sugar and sugar polymers as exogenous contrast agents, which is possible based on the exchange of their hydroxyl protons with water protons. While this capability has raised early enthusiasm, for instance about the possibility to image D‐glucose metabolism with MRI in a way analogous to PET, experience over the past decade has shown that this is not trivial. On the other hand, many studies have confirmed the possibility to image a large variety of sugar analogues, each with potentially interesting applications to assess tissue physiology. Some promising applications are the study of (i) sugar delivery and transport to assess blood brain barrier integrity, (ii) sugar uptake by cells for their characterization (e.g. cancer vs healthy), as well as (iii) clearance of sugars to assess tissue drainage for instance through the glymphatic system. To judge these opportunities and their challenges, especially in the clinic, it is needed to understand the technical aspects of detecting the presence of rapidly exchanging protons through the water signal in MRI, especially as a function of magnetic field strength. We expect that novel approaches in terms of MRI detection (both saturation transfer and relaxation based), MRI data analysis, and sugar design will push this young field forward in the next decade.
... Both oral and rectal administration of NAG resulted in clear clinical and endoscopic or radiological improvement. 196 In adults with IBD, treatment with 6 g NAG orally for 4 weeks resulted in an 88.1% response rate for overall clinical symptoms; a 58.8% response for abdominal pain with a 49% reduction in symptom score; a 64.7% response for diarrhoea with a 47% reduction in symptom score. There were also significant reductions in symptom scores for nausea, passage of mucus and rectal bleeding. ...
Inflammatory bowel disease (IBD) has a complex multifactorial aetiology involving interactions between environmental factors (including diet), the microbiome, genetics and the immune system, leading to dysfunctional immune responses and chronic inflammation. Dietary factors and gut dysbiosis have emerged as important treatment targets in the management of IBD as they are involved in the initiation and perpetuation of inflammation, and subsequently disease development and progression. Specific dietary approaches and nutritional interventions have some, albeit limited, clinical evidence to suggest they can modify gene expression, have anti-inflammatory effects, induce mucosal healing, normalise intestinal microbiota, reduce disease activity and/or help maintain remission. This review uses evidence from nutritional science to propose a theoretical pragmatic model for the personalisation of nutritional therapy in patients with active or latent IBD, incorporating disease-modifying dietary recommendations and nutrient-based supplements, primarily as adjuvant therapies, with the intention to stimulate further investigation and research.
... Recently, GlcNAc was tested as a therapy for osteoarthritis (Shikhman et al. 2005), gastrointestinal inflammation (Salvatore et al. 2000), and as a contrast agent for imaging and diagnosing cancers (Rivlin and Navon 2016). N-acetylglucosamine can be prepared chemically or enzymatically, although chemical production from chitin is expensive and inefficient (yields less than 65%) and generates acidic waste from HCl and acetic anhydride (Chen et al. 2010). ...
Using commercial API-ZYM screening kits, highly active α-glucosidase, β-glucosidase, and β-N-acetylglucosaminidase were found in Grifola frondosa, having potential for carbohydrate utilization. Of these, β-N-acetylglucosaminidase, which converts chitin to N-acetylglucosamine, was purified and characterized. The recovery was 24.5%, and the purified enzyme had a specific activity 0.67 U/mg protein. Chitinase activity was confirmed by zymogram analysis. The enzyme was also shown to be β-N-acetylglucosaminidase, as N-acetylglucosamine was the main hydrolysis product from colloidal chitin. Thus, the molecule was named NAG38, to indicate β-N-acetylglucosaminidase activity and a molecular weight of 38 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Enzymatic activity was optimal at pH 7.0 and 50 °C, with Km and Vmax values of 0.112 mM and 0.570 μmol/min/mg protein against p-nitrophenyl N-acetyl-β-D-glucosaminide. The bioactivity was inhibited by Hg2+, Ag+, Mg2+, Zn2+, Ca2+, and Mn2+, with residual enzyme bioactivity only 11.1% after incubation in Hg2+, but was not substantially inhibited by Ba2+, K+, and Na+.
... GlcN supplement has been used in the prevention and treatment of osteoarthritis symptoms [Bruyere & Reginster, 2007;Hrynets et al., 2016;McAlindon et al., 2000]. Although not without debates, other health claims reported for GlcN include improvement and ease of inflammatory bowel diseases (3-6 g of N-acetyl glucosamine administered orally or rectally to children daily for unspecified period) [Salvatore et al., 2000]; bone healing and pain alleviation (230 mg/kg glucosamine-sulfate daily intraperitoneal for 4 weeks to Wistar rats) [Uğraş et al., 2013]; as well as treatment of immunological diseases (10 μg/mL of 5-40 mM d-GlcN or deoxyfructosazines on Jurkat cells) [Zhu et al., 2007]. Aside from these potential health benefits associated with GlcN, this amino sugar could also find applications in the food industry since several studies have reported its antimicrobial [Hrynets et al., 2016], antioxidant [Gottardi et al., 2014;Xing et al., 2006] and flavour/ taste enhancing potentials [Fu et al., 2020], especially when incubated at moderate temperatures (between 25 and 50°C). ...
Aside from the possible health benefit of dietary consumption of glucosamine (GlcN), studies have also reported its flavour enhancing properties in varying food products. However, the impact of its inclusion on other quality attributes of meat products has been under-assessed. The present study examined the effect of the addition of ascorbic acid (0.1%) and varying levels of GlcN (0.75, 1.5 and 3.0%) on colour stability, textural as well as sensory attributes of beef burger. Except for L * (lightness) value, significant interaction ( p
... Their involvement in several biomolecular processes has carved out a niche for GAGs in clinical therapeutics. For example, chondroitin and hyaluronate are used in different pharmaceutical and nutraceutical formulations for the treatment of osteoarthritis [8][9][10][11]; heparin and its mimetics are used as anticoagulants for treating thrombosis; keratan sulphate is incorporated in ophthalmic products for treating certain eye defects and as biomarker for female genital tract carcinoma [12]. Beyond their use in different capacities as a replacement therapy, recent studies have suggested additional roles as possible therapeutic agents in inhibiting cell invasion by viruses causing severe acute respiratory syndrome (SARS) diseases [13,14]. ...
The increasing recognition of the biochemical importance of glycosaminoglycans (GAGs) has in recent times made them the center of attention of recent research investigations. It became evident that subtle conformational factors play an important role in determining the relationship between the chemical composition of GAGs and their activity. Therefore, a thorough understanding of their structural flexibility is needed, which is addressed in this work by means of all-atom molecular dynamics (MD) simulations. Four major GAGs with different substitution patterns, namely hyaluronic acid as unsulphated GAG, heparan-6-sulphate, chondroitin-4-sulphate, and chondroitin-6-sulphate, were investigated to elucidate the influence of sulphation on the dynamical features of GAGs. Moreover, the effects of increasing NaCl and KCl concentrations were studied as well. Different structural parameters were determined from the MD simulations, in combination with a presentation of the free energy landscape of the GAG conformations, which allowed us to unravel the conformational fingerprints unique to each GAG. The largest effects on the GAG structures were found for sulphation at position 6, as well as binding of the metal ions in the absence of chloride ions to the carboxylate and sulphate groups, which both increase the GAG conformational flexibility.
... 55 Similarly, intake of dietary fiber has been linked to improved outcomes in patients with coronary heart disease, 51 and intake of glycosaminoglycans has been studied as a treatment for arthritis 58 and inflammatory bowel disease. 59 These examples identify the potential to harness the specific properties of a wide range of polysaccharides to be used for medical benefit, even without additional engineering design. ...
Polysaccharides are an important class of biomolecules with many different biological functions and unique properties, thus it is unsurprising that polysaccharides are heavily researched as materials solutions in medicine and dentistry. This dissertation explores the potential of harnessing inherent and well-understood biological properties of polysaccharides, using chemical and materials modification techniques to create clinically useful systems for medical and dental challenges. Engineered polysaccharides systems were prepared and characterized, including starch nanoparticles with control of particle size, charge, loading, and attachment of functional molecules, and glycocalyx-mimetic polymer brushes. These systems were applied as a diagnostic aid for dental caries, as an anti-bacterial treatment, and in targeting tumor-associated macrophages. In the first application, fluorescent cationic (+5.8±1.2 mV) starch nanoparticles (size 101±56 nm) were prepared to target and adhere to early caries lesions to facilitate optical detection, test lesion activity, and monitor the impact of remineralization treatments in vitro. In the second application, similarly designed starch nanoparticles (size 440±58 nm) were loaded with antibacterial copper nanoparticles (6-7nm size, ~0.35% loading) to create a system which targets bacteria electrostatically and by their enzymatic metabolic processes. This system showed high antibacterial efficacy (3-log and 7-log bacterial reductions for S. aureus and B. subtilis, respectively, for copper nanoparticle dose of 17 µg/ml). The final application demonstrated high positive predictive value (>0.8 for M2 over M1) for cellular binding of glycocalyx-mimetic mannose-coatings with M2-polarized tumor-associated macrophages, with potential applications in cancer diagnostics and therapeutics. These examples highlight the utility of modified polysaccharides in the design of clinically useful systems in medicine and dentistry.
... Human clinical trials for NAG as treatment for osteoarthritis have nearly universally employed a dose of 1500 mg/day [15,23], closely aligning with the 1400 mg/day total dosing in the current study. In a pilot study by Salvatore et al., NAG was administered in doses ranging from 3 to 6 g with no adverse side effects of the treatment noted [24]. NAG is safe when administered intravenously in quantities as large as 20 g in humans, with no toxicity or alteration of blood glucose concentration [16,25]; likewise, the long-term safety of NAG has been endorsed due to the relative absence of treatment-related adverse effects in the literature [26]. ...
Background
Coronavirus disease 2019 (COVID-19) has affected millions globally, with a continued need for effective treatments. N-acetylglucosamine has anti-inflammatory activities and modulates immune response. This study evaluated whether N-acetylglucosamine administered orally improves clinical outcomes for patients admitted to the hospital due to COVID-19.
Materials and methods
This single-center, prospective, observational cohort study used a retrospective control group for comparison. Multivariate analyses evaluated whether N-acetylglucosamine was an independent predictor of primary outcomes (rate of intubation, hospital length-of-stay, and mortality) and select secondary outcomes (intensive care unit [ICU] admission, ICU length-of-stay, supplemental oxygen use duration, hospice initiation, and poor clinical outcome [defined as combined hospice initiation/death]).
Results
Of the 50 patients enrolled in the N-acetylglucosamine treatment group, 48 patients had follow-up data (50.0% [24/48] male; median age 63 years, range: 29–88). Multivariate analysis showed the treatment group had improved hospital length-of-stay (β: 4.27 [95% confidence interval (CI) −5.67; −2.85], p < 0.001), ICU admission (odds ratio [OR] 0.32 [95% CI 0.10; 0.96], p = 0.049), and poor clinical outcome (OR 0.30 [95% CI 0.09; 0.86], p = 0.034). Mortality was significantly lower for treatment versus control on univariate analysis (12.5% vs. 28.0%, respectively; p = 0.039) and approached significance on multivariate analysis (p = 0.081).
Conclusions
N-acetylglucosamine administration was associated with reduced hospital length-of-stay, ICU admission rates, and death/hospice rates in adults with COVID-19 compared to those who received standard care alone. An upcoming trial will further investigate N-acetylglucosamine's effects.
Trial Registration
NCT04706416.
... For example, large prospective cohort studies [11][12][13][14] involving glucosamine alone and in combination with chondroitin have suggested a reduced association of risk for developing colorectal cancers. Additionally, animal [15] and human [16] models have reported improvements in inflammatory bowel disease after glucosamine administration. In considering this data, other potential roles of glucosamine in human health and associated mechanisms of action may be evident, and other mechanisms of action, besides the proposed biochemical mechanisms related to the joints (i.e., cytokine and enzyme changes in the joints' chondrocytes, synoviocytes and synovial fluid), should be investigated to elucidate the potential benefits seen systemically by glucosamine supplementation. ...
Glucosamine (GLU) is a natural compound found in cartilage, and supplementation with glucosamine has been shown to improve joint heath and has been linked to reduced mortality rates. GLU is poorly absorbed and may exhibit functional properties in the gut. The purpose of this study was to examine the impact of glucosamine on gastrointestinal function as well as changes in fecal microbiota and metabolome. Healthy males (n = 6) and females (n = 5) (33.4 ± 7.7 years, 174.1 ± 12.0 cm, 76.5 ± 12.9 kg, 25.2 ± 3.1 kg/m 2 , n = 11) completed two supplementation protocols that each spanned three weeks separated by a washout period that lasted two weeks. In a randomized, double blind , placebo-controlled, crossover fashion, participants ingested a daily dose of GLU hydro-chloride (3000 mg GlucosaGreen ® , TSI Group Ltd., USA) or maltodextrin placebo. Study participants completed bowel habit and gastrointestinal symptoms questionnaires in addition to providing a stool sample that was analyzed for fecal microbiota and metabolome at baseline and after the completion of each supplementation period. GLU significantly reduced stomach bloating and showed a trend towards reducing constipation and hard stools. Phylogenetic diversity (Faith's PD) and proportions of Pseudomonadaceae, Peptococcaceae, and Bacillaceae were significantly reduced following GLU consumption. GLU supplementation significantly reduced individual, total branched-chain, and total amino acid excretion, with no glucosamine being detected in any of the fecal samples. GLU had no effect on fecal short-chain fatty acids levels. GLU supplementation provided functional gut health benefits and induced fecal microbiota and metabolome changes.
... Here, downregulation of uridine diphosphate-N-acetylglucosamine and upregulation of ATP in serum indicated that most N-AG6P generated likely can be converted into N-acetyl-D-glucosamine (N-AG) (a polysacchatide) and ATP, via N-acetyl-D-glucosamine kinase (NAGK). The resulting N-AG has confirmed its antiinflammatory efficacy for inflammatory bowel disease (51). It is worth mentioning that betaine, which might be synthesized from choline, can be degraded via two pathways. ...
The effects of dietary supplementation with guava leaf extracts (GE) on intestinal barrier function and serum and fecal metabolome in weaned piglets challenged by enterotoxigenic Escherichia coli (ETEC) were investigated. In total, 50 weaned piglets (Duroc × Yorkshire × Landrace) from 25 pens (two piglets per pen) were randomly divided into five groups: BC (blank control), NC (negative control), S50 (supplemented with 50 mg kg⁻¹ diet GE), S100 (100 mg kg⁻¹ diet GE), and S200 (200 mg kg⁻¹ diet GE), respectively. On day 4, all groups (except BC) were orally challenged with enterotoxigenic ETEC at a dose of 1.0 × 10⁹ colony-forming units (CFUs). After treatment for 28 days, intestinal barrier function and parallel serum and fecal metabolomics analysis were carried out. Results suggested that dietary supplementation with GE (50–200 mg kg⁻¹) increased protein expression of intestinal tight junction proteins (ZO-1, occludin, claudin-1) (p < 0.05) and Na⁺/H⁺ exchanger 3 (NHE3) (p < 0.05). Moreover, dietary supplementation with GE (50–200 mg kg⁻¹) increased the level of tetrahydrofolic acid (THF) and reversed the higher level of nicotinamide-adenine dinucleotide phosphate (NADP) induced by ETEC in serum compared with the NC group (p < 0.05), and enhanced the antioxidant capacity of piglets. In addition, dietary addition with GE (100 mg kg⁻¹) reversed the lower level of L-pipecolic acid induced by ETEC in feces compared with the NC group (p < 0.05) and decreased the oxidative stress of piglets. Collectively, dietary supplementation with GE exhibited a positive effect on improving intestinal barrier function. It can reprogram energy metabolism through similar or dissimilar metabolic pathways and finally enhance the antioxidant ability of piglets challenged by ETEC.
... Here, downregulation of uridine diphosphate-Nacetylglucosamine and upregulation of ATP in serum indicated that most N-AG6P generated likely can be converted into N-acetyl-D-glucosamine (N-AG) (a polysacchatide) and ATP, via N-acetyl-D-glucosamine kinase (NAGK). The resulting N-AG has been con rmed its anti-in ammatory e cacy for in ammatory bowel disease [57]. It is worth mentioning that betaine, which might be synthesized from choline, can be degraded via two pathways. ...
Background: The effects of dietary supplementation with guava leaf extracts (GE) on growth performance, diarrhea and intestinal barrier function, as well as associated with its modulation of serum and fecal metabolic changes in weaned piglets challenged by enterotoxigenic Escherichia coli (ETEC) were investigated.
Method: Fifty weaned piglets (Duroc × Yorkshire × Landrace) from 5 pens (2 piglets per pen) were randomly divided into five groups: blank control group (BC), negative control group (NC), or those supplemented with 50 mg kg⁻¹ (S50), 100 mg kg⁻¹ (S100), or 200 (S200) mg kg⁻¹ diet GE, respectively. On day 4, all piglets (except for BC) were orally challenged with about 1.0 × 10⁹ colony-forming units (CFU) enterotoxigenic ETEC. After 28-day trial, growth performance, diarrhea incidence, intestinal barrier function and metabolomics of serum and fecal were investigated.
Results: We demonstrated that dietary supplementation with GE (50-200 mg kg⁻¹) reduced diarrhea incidence of piglets and increased expression of intestinal tight junction proteins (ZO-1, Occludin, Claudin-1) (P < 0.05) and sodium hydrogen exchanger 3 (NHE3) (P < 0.05). Moreover, dietary supplementation with GE (50-200 mg kg⁻¹) upregulated level of tetrahydrofolic acid (THF) and reversed higher level of nicotinamide-adenine dinucleotide phosphate (NADP) caused by ETEC in serum compared with NC group (P < 0.05), and enhanced antioxidant ability of piglets. In addition, dietary addition with GE (100 mg kg⁻¹) reversed the lower level of L-pipecolic acid caused by ETEC in feces compared with NC group (P < 0.05), and decreased oxidative stress response of piglets. Further, there were no differences (P > 0.05) in the final weight, average daily feed intake (ADFI) and F/G among dietary groups during the overall period, and piglets in S50 group has the higher average daily gain (ADG).
Conclusion: Dietary supplementation with 50-200 mg kg⁻¹ GE reduced diarrhea incidence of weaned piglets challenged by ETEC and exhibited positive effect on improving intestinal barrier function. Meanwhile, dietary addition with GE organized and redistributed energy resources through similar or dissimilar metabolic pathways, and finally enhanced antioxidant ability of piglets challenged by ETEC.
... D-glucosamine (GlcN) and N-acetyl-d-glucosamine (GLcNAc) are naturally occurring amino sugars and essential carbohydrate components of biologically important glycoproteins, glycolipids, and glycosaminoglycans. GlcN has therapeutic potential in the treatments of various diseases including osteoarthritis, inflammatory bowel disease and gastritis [13]. GlcN has excellent antioxidant activities, as manifested by a strong chelating effect on ferrous ions and protection of macromolecules such as protein, lipid, and deoxyribose from oxidative damage induced by hydroxyl radicals [14]. ...
Glucosamine is known as anti-inflammatory, antioxidant and as neuroprotective as well as using to treat many of diseases. This work aimed to investigate the remedial effect of glucosamine (20mg/kg b.wt) against the damage induced by a single dose of γ-radiation (8Gy) or aluminium chloride (AlCl3) (100mg/kg b.wt) in the heart and brain tissues of female rats. Serum aspartate aminotransferase (AST), cholesterol, triglycerides (TGs), LDH and creatine kinase (CPK) were measured. Moreover, gene expression of amyloid protein precursor (APP) and seladin-1 were estimated in the brain tissue. Also, acetylcholinesterase activity (AChE) and p-tau protein expression were estimated in brain homogenate. Metallothioneine (MT) was estimated in the heart and brain tissues. Heart and brain histopathological examination was performed. Irradiation significantly decreased serum AST, CPK and LDH, as well as MT levels in heart and brain tissues. Also, gene expression of seladin-1 decreased. On the other hand, irradiation significantly increased serum TGs level and brain AchE activity, tau protein, and β-amyloid percursor (APP). AlCl3 administration (21 days) induced disturbance in most of the estimated parameters, especially AST, TGs, and MT. Glucosamine treatment with irradiation or AlCl3 improved most of the measured parameters. In addition, histopathological examination confirmed the biochemical results. In conclusion: Glucosamine could be used to improve the heart and brain damages induced by γ-radiation exposure or AlCl3.
... The therapeutic potential of GlcNAc is mainly attributed to its anti-inflammatory and chondroprotective effects (Dalirfardouei et al., 2016). GlcNAc also shows promising therapeutic efficacy in treatment of chronic inflammatory bowel disease by restoring the intestinal matrix and improving the epithelial morphology (Salvatore et al., 2000). As GlcNAc is non-toxic, this compound should be further explored to determine its potential of being used as an antibiotic adjuvant for treatment of chronic and recurrent infections in immunocompromised patients caused by members of Enterobacteriaceae. ...
Bacterial tolerance to antibiotics causes reduction in efficacy in antimicrobial treatment of chronic and recurrent infections. Nutrient availability is one major factor that determines the degree of phenotypic antibiotic tolerance. In an attempt to test if specific nutrients can reverse phenotypic tolerance, we identified N-acetyl-D-glucosamine (GlcNAc) as a potent tolerance-suppressing agent and showed that it could strongly re-sensitize a tolerant population of E. coli to ampicillin. Such re-sensitization effect was attributable to two physiology-modulating effects of GlcNAc. First, uptake of GlcNAc by the tolerant population triggers formation of the peptidoglycan precursor UDP-N-acetyl-D-glucosamine (UDP-GlcNAc) and subsequently re-activates the peptidoglycan biosynthesis process, rendering the organism susceptible to β-lactam antibiotics. Second, activation of glycolysis by-products of GlcNAc catabolism drives the re-sensitization process. Our findings imply that GlcNAc may serve as a non-toxic β-lactam adjuvant that enhances the efficacy of treatment of otherwise hard-to-treat bacterial infections due to phenotypic antibiotic tolerance.
... GlcNAc has been reported to have an anti-in ammatory impact during several in ammatory diseases by modulating NFκB activity. [78][79][80] Investigating the potential direct impact of these glycans on innate immune functions and in ammation, and how this affects HIV control during ART, warrants further investigations. Glycoproteins can also be shed from cells in different organs; therefore, their characteristics can re ect these cells' functions. ...
Non-invasive biomarkers that predict HIV remission after antiretroviral therapy (ART) interruption are urgently needed. Such biomarkers can improve the safety of analytic treatment interruption (ATI) and provide mechanistic insights into the pathways involved in post-ART HIV control. We identified plasma glycomic and metabolic signatures of time-to-viral-rebound and probability-of-viral-rebound using samples from two independent cohorts. These samples include a large number of post-treatment controllers, a rare population demonstrating sustained virologic suppression after ART-cessation. The signatures remained significant after adjusting for key demographic and clinical confounders. We also confirmed a mechanistic link between biomarkers and HIV latency reactivation and myeloid inflammation in vitro . Finally, machine learning algorithms selected sets of biomarkers that predict time-to-viral-rebound with 74–76% capacity and probability-of-viral-rebound with 97.5% capacity. In summary, we fill a major gap in HIV cure research by identifying non-invasive biomarkers, with potential functional significance, that predict duration and probability of viral remission after treatment interruption.
... In this study, 8 out of the 12 children studied went into clinical remission. 182 However, the specific therapeutic effect of GlcNAc in the modulation of T-cells functions was not understood at that time. ...
Carbohydrate structures (glycans) cover the surface of all mammalian cells, being fundamental for inter- and intracellular signaling, immune defense, inflammation, cell adhesion and pathogen invasion, both in health and disease. Alterations in the glycome (repertoire of glycans structures in an organism) are known to occur in several gastrointestinal and liver diseases, including inflammatory and autoimmune disorders as well as in cancer. The lack of effective (early) diagnosis, accurate prognostic markers and targeted treatments for these gastrointestinal pathologies highlights the unmet need to develop novel biomarkers and therapeutic strategies. In this context, protein glycosylation has emerged as a groundbreaking approach to mechanistically understand the pathogenesis of the different gastrointestinal diseases with the promise to reveal novel glycan-based biomarkers and treatments.
This chapter encompasses updated evidences on the relevance of cellular glycosylation in the immunopathogenesis of gastrointestinal disorders, with a focus on inflammatory bowel disease, inflammatory hepatic disorders, gastrointestinal and liver cancers, highlighting the potential of glycans as effective biomarkers and innovative therapeutic and preventive strategies with clinical applications.
... Moreover, treatment with insulin had no effect on the serum half-life of GlcNAc (63). Oral GlcNAc (3-6g/day) has also been used in 12 children with inflammatory bowel disease for ~2 years without reported toxicities and/or side effects (65). In rats, chronic systematic toxicological studies at doses of 2323-2545mg/kg/day for up to 114 weeks found no toxicity (66,67). ...
Myelination plays an important role in cognitive development and in demyelinating diseases like multiple sclerosis (MS), where failure of re-myelination promotes permanent neuro-axonal damage. Modification of cell surface receptors with branched N-glycans coordinates cell growth and differentiation by controlling glycoprotein clustering, signaling and endocytosis. N-acetylglucosamine (GlcNAc) is a rate-limiting metabolite for N-glycan branching. Here we report that GlcNAc and N-glycan branching trigger oligodendrogenesis from precursor cells by inhibiting PDGF receptor-α cell endocytosis. Supplying oral GlcNAc to lactating mice drives primary myelination in newborn pups via secretion in breast milk, while genetically blocking N-glycan branching markedly inhibits primary myelination. In adult mice with toxin (cuprizone) induced demyelination, oral GlcNAc prevents neuro-axonal damage by driving myelin repair. In MS patients, endogenous serum GlcNAc levels inversely correlated with imaging measures of demyelination and microstructural damage. Our data identifies N-glycan branching and GlcNAc as critical regulators of primary myelination and myelin repair and suggests oral GlcNAc may be neuro-protective in demyelinating diseases like MS.
N-acetyl glucosamine (NAG) is a natural amino sugar found in various human tissues with previously described anti-inflammatory effects. Various chemical modifications of NAG have been made to promote its biomedical applications. In this study, we synthesized two bi-deoxygenated NAG, BNAG1 and BNAG2 and investigated their anti-inflammatory properties, using an in vivo and in vitro inflammation mouse model induced by lipopolysaccharide (LPS). Among the parent molecule NAG, BNAG1 and BNAG2, BNAG1 showed the highest inhibition against serum levels of IL-6 and TNF α and the leukocyte migration to lungs and peritoneal cavity in LPS challenged mice, as well as IL-6 and TNF α production in LPS-stimulated primary peritoneal macrophages. BNAG2 displayed an anti-inflammatory effect which was comparable to NAG. These findings implied potential application of these novel NAG derivatives, especially BNAG1, in treatment of certain inflammation-related diseases.
The wastes generated by the shrimp industry are approximately between 50 and 60% of the catch volume. These residues such as head, viscera, and shell are potential pollutants if they are not treated for proper disposal. One way to solve this problem is to use the residues as functional food ingredients. In this regard, shrimp residues are rich in chitin, the second most abundant biopolymer on the planet after cellulose. Chitin is composed of N-acetyl glucosamine, a molecule used as a sweetener in the food industry and as an aid in the treatment of coronary diseases and gonarthrosis. N-acetyl glucosamine can be obtained by the hydrolysis of colloidal chitin using chemical or enzymatic methods; however, chemical methods are associated with pollution. In this study, we determined the hydrolysis conditions of shrimp colloidal chitin for obtaining N-acetyl glucosamine, using the extracellular enzymes produced by a marine bacterium isolated in the coastal zone of Progreso, Yucatan, Mexico. The best N-acetyl glucosamine yield obtained was 2.65%, using 10 mg/mL colloidal chitin, at 60°C, and pH 8.9 with 3.5% NaCl.
Severe acute malnutrition (SAM) is the most life-threatening form of undernutrition and underlies at least 10% of all deaths among children younger than 5 years in low-income countries. SAM is a complex, multisystem disease, with physiological perturbations observed in conjunction with the loss of lean mass, including structural and functional changes in many organ systems. Despite the high mortality burden, predominantly due to infections, the underlying pathogenic pathways remain poorly understood. Intestinal and systemic inflammation is heightened in children with SAM. Chronic inflammation and its consequent immunomodulation may explain the increased morbidity and mortality from infections in children with SAM, both during hospitalization and in the longer term after discharge. Recognition of the role of inflammation in SAM is critical in considering new therapeutic targets in this disease, which has not seen a transformational approach to treatment for several decades. This review highlights the central role of inflammation in the wide-ranging pathophysiology of SAM, as well as identifying potential interventions that have biological plausibility based on evidence from other inflammatory syndromes.
Multiple studies confirm use of Integrative Health (IH) therapies is common among children with IBD. Pediatric prevalence rates are compatible with or exceed IH use in adult IBD. Surveys indicate that biologically-based therapies are the most frequently utilized modality among the pediatric IBD population. Concurrent use of herbal remedies and dietary supplements (which we will define as biologically based IH therapies for the purpose of this chapter) and prescription medication is common and may cause untoward drug interactions. In this chapter, we review the available evidence for the safety and efficacy of the most commonly used biologically-based therapies and mind-body therapies in IBD. Clinicians need to know the prevalence of IH therapy utilization in the pediatric IBD population, parents’ receptivity towards these modalities as adjuvant therapies, and the reticence to disclose utilization. We suggest that maintenance of a cursory level of understanding and awareness of IH modalities, including knowledge of efficacy, interactions and contraindications, is essential to ensure patient safety.
The host-guest incompatibility between a production host and non-native enzymes has posed an arduous challenge for synthetic biology, particularly between mesophile-derived enzymes and a thermophilic chassis. In the present study, we develop a thermophilic enzyme mining strategy comprising an automated co-evolution-based screening pipeline (http://cem.sjtu.edu.cn), computation-based enzyme characterization, and gene synthesis-based function validation. Using glucosamine-6-phosphate acetyltransferase (GNA1) as an example, we successfully mined four novel GNA1s with excellent thermostabilities and catalytic performances. Calculation and analysis based on AlphaFold2-generated structures were also conducted to uncover the mechanism underlying their excellent properties. Finally, our mined GNA1s were used to enable the high-temperature N-acetylglucosamine (GlcNAc) production with high titers of up to 119.3 g/L, with the aid of systems metabolic engineering and temperature programming. This study demonstrates effectiveness of the enzyme mining strategy, highlighting the application prospects of mining new enzymes from massive databases and providing an effective solution for tackling host-guest incompatibility.
Glycosylation has a profound influence on protein activity and cell biology through a variety of mechanisms, such as protein stability, receptor interactions and signal transduction. In many rheumatic diseases, a shift in protein glycosylation occurs, and is associated with inflammatory processes and disease progression. For example, the Fc-glycan composition on (auto)antibodies is associated with disease activity, and the presence of additional glycans in the antigen-binding domains of some autoreactive B cell receptors can affect B cell activation. In addition, changes in synovial fibroblast cell-surface glycosylation can alter the synovial microenvironment and are associated with an altered inflammatory state and disease activity in rheumatoid arthritis. The development of our understanding of the role of glycosylation of plasma proteins (particularly (auto)antibodies), cells and tissues in rheumatic pathological conditions suggests that glycosylation-based interventions could be used in the treatment of these diseases.
The diversity of glycan presentation in a cell, tissue and organism is enormous, which reflects the huge amount of important biological information encoded by the glycome which has not been fully understood. A compelling body of evidence has been highlighting the fundamental role of glycans in immunity, such as in development, and in major inflammatory processes such as inflammatory bowel disease, systemic lupus erythematosus and other autoimmune disorders. Glycans play an instrumental role in the immune response, integrating the canonical circuits that regulate innate and adaptive immune responses. The relevance of glycosylation in immunity is demonstrated by the role of glycans as important danger-associated molecular patterns and pathogen-associated molecular patterns associated with the discrimination between self and non-self; also as important regulators of the threshold of T cell activation, modulating receptors signalling and the activity of both T and other immune cells. In addition, glycans are important determinants that regulate the dynamic crosstalk between the microbiome and immune response. In this chapter, the essential role of glycans in the immunopathogenesis of inflammatory disorders will be presented and its potential clinical applications (diagnosis, prognosis and therapeutics) will be highlighted.
The recent outbreak and transmission of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) worldwide and the ensuing coronavirus disease 2019 (COVID‐19) pandemic has left us scrambling for ways to contain the disease and develop vaccines that are safe and effective. Equally important, understanding the impact of the virus on the host system in convalescent patients, healthy otherwise or with co‐morbidities, is expected to aid in developing effective strategies in the management of patients afflicted with the disease. Viruses possess the uncanny ability to redirect host metabolism to serve their needs and also limit host immune response to ensure their survival. An ever‐increasingly powerful approach uses metabolomics to uncover diverse molecular signatures that influence a wide array of host signalling networks in different viral infections. This would also help integrate experimental findings from individual studies to yield robust evidence. In addition, unravelling the molecular mechanisms harnessed by both viruses and tumours in their host metabolism will help broaden the repertoire of therapeutic tools available to combat viral disease.
Food waste (FW) remains a global challenge due to the increasing demand for food production to support a growing global population and the lack of effective waste management technologies for recycling and upcycling. Unique compounds in FW-such as carbohydrates, proteins, lignin, fats, and extractives-can be repurposed to produce important biobased fuels, bulk chemicals, dietary supplements, adsorbents, and antibacterial products, among many others. We review the thermal and thermocatalytic FW valorization strategies and the fundamental pathways. We discuss the potential integration of various valorization processes, their economic viability, the technical and marketing challenges, and the need for further developments. By overcoming several technical hurdles, repurposing FW into modular plants can create exciting economic and environmental prospects. This journal is
The glycosylation of the fragment crystallizable (Fc) region of immunoglobulins (Ig) is critical for the modulation of antibody effects on inflammation. Moreover, antibody glycosylation may induce pathologic modifications and ultimately contribute to the development of autoimmune diseases. Thanks to progress in the analysis of glycosylation, more data are available on IgG and its subclass structures in the context of autoimmune diseases. In this review, we focused on the impact of Ig glycosylation in autoimmunity, describing how it modulates the immune response and how glycome profiles can be used as biomarkers of disease activity. The analysis of antibody glycosylation demonstrated specific features in human autoimmune and chronic inflammatory conditions, including rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease and autoimmune liver diseases, among others. Within the same disease, different patterns are associated with disease severity and treatment options. Future research may increase the information available on the distinct glycome profiles and expand their potential role as biomarkers and as targets for treatment, ultimately favoring an individualized approach.
In nature, distinct number of renewable biopolymers are available which exist as chief starting material for various bioprocesses; chitin being one of them that is degraded by the chitinases. Chitinases belong to the family of hydrolytic enzymes that hydrolyses chitin and it is also used in various industries for waste management, recovery of tannase, as biocontrol agent, chitooligosaccharides and GlcNAc production, etc. In the current paper, various chitinases sources are discussed available worldwide such as bacteria, fungal, plants, mammals, etc. At laboratory scale, purification and characterisation of various chitinases have been performed but several difficulties arise at industrial scale due to expensive purification steps. This review summarises the developments in production, extraction, purification and various applications of chitinases.
Purpose
Childhood stricturing Crohn’s disease (CD) has significant morbidity. Interventions including resection, stricturoplasty and endoscopic balloon dilatation (EBD) are often required. Optimal intervention modality and timing, and use of adjuvant medical therapies, remains unclear. We aim to review the therapies used in paediatric stricturing CD.
Methods
A systematic review in accordance with PRISMA was performed (PROSPERO: CRD42020164464). Demographics, stricture features, interventions and outcomes were extracted.
Results
Fourteen studies were selected, including 177 patients (183 strictures). Strictures presented at 40.6 months (range 14–108) following CD diagnosis. Medical therapy was used in 142 patients for an average of 20.4 months (2–36), with a complete response in 11 (8%). Interventions were undertaken in 138 patients: 53 (38%) resections, 39 (28%) stricturoplasties, and 17 (12%) EBD. Complications occurred in 11% of resections, versus 15% stricturoplasties, versus 6% EBD ( p = 0.223). At a median follow-up of 1.9 years (interquartile range 1.2–2.4) pooled stricture recurrence was 22%. Resection had 9% recurrence, versus 38% stricturoplasty, versus 47% EBD ( p < 0.001).
Conclusions
Resection is associated with a low incidence of recurrence and complications. There remains a paucity of evidence regarding adjuvant medical therapy and the role of EBD. We propose a minimum reported dataset for interventions in paediatric stricturing CD.
Non-invasive biomarkers that predict HIV remission after antiretroviral therapy (ART) interruption are urgently needed. Such biomarkers can improve the safety of analytic treatment interruption (ATI) and provide mechanistic insights into the pathways involved in post-ART HIV control. We identified plasma glycomic and metabolic signatures of time-to-viral-rebound and probability-of-viral-rebound using samples from two independent cohorts. These samples include a large number of post-treatment controllers, a rare population demonstrating sustained virologic suppression after ART-cessation. The signatures remained significant after adjusting for key demographic and clinical confounders. We also confirmed a mechanistic link between biomarkers and HIV latency reactivation and myeloid inflammation in vitro . Finally, machine learning algorithms selected sets of biomarkers that predict time-to-viral-rebound with 74-76% capacity and probability-of-viral-rebound with 97.5% capacity. In summary, we fill a major gap in HIV cure research by identifying non-invasive biomarkers, with potential functional significance, that predict duration and probability of viral remission after treatment interruption.
We characterized the mechanisms by which recombinant (r) tumor necrosis factor (TNF), IFN-gamma, and IL-1, alone and in combination, regulate human lung fibroblast hyaluronic acid (HA) production. Each cytokine stimulated fibroblast HA production. The combination of rTNF and rIFN-gamma resulted in a synergistic increase in the production of high molecular weight HA. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous decrease in HA degradation. In contrast, when rTNF and rIL-1 were combined, an additive increase in low molecular weight HA was noted. This was due to a synergistic increase in hyaluronate synthetase activity and a simultaneous increase in HA degradation. Human lung fibroblasts contained a hyaluronidase that, at pH 3.7, depolymerized high molecular weight HA to 10-40 kD end products of digestion. However, hyaluronidase activity did not correlate with fibroblast HA degradation. Instead, HA degradation correlated with fibroblast-HA binding, which was increased by rIL-1 plus rTNF and decreased by rIFN-gamma plus rTNF. Recombinant IL-1 and rTNF weakly stimulated and rIL-1 and rTNF in combination further augmented the levels of CD44 mRNA in lung fibroblasts. In contrast, rIFN-gamma did not significantly alter the levels of CD44 mRNA in unstimulated or rTNF stimulated cells. These studies demonstrate that rIL-1, rTNF, and rIFN-gamma have complex effects on biosynthesis and degradation which alter the quantity and molecular weight of the HA produced by lung fibroblasts. They also show that fibroblast HA degradation is mediated by a previously unrecognized lysosomal-type hyaluronidase whose function may be regulated by altering fibroblast-HA binding. Lastly, they suggest that the CD44 HA receptor may be involved in this process.
There is increasing evidence that the glycosaminoglycan (GAG) component of the vascular endothelium is important in regulating vascular permeability, throm-boresistance and cellular interactions. We have investigated the GAG metabolism of cultured human umbilical vein endothelial cells (HUVEC) in response to a range of inflammatory stimuli. Using both chemical measurement of cellular and supernatant GAGS and 35S labelling to identify newly synthesised GAGS, interleukin 1 (ILI), tumour necrosis factor (TNF) and interferon gamma (IFN γ) were shown to influence sulphated GAG metabolism significantly. ILI and TNF caused a marked increase in culture supernatant GAGS and a concomitant reduction in cell-associated GAGS.
This was shown histochemically to be associated with a marked reduction and redistribution of endothelial surface anionic sites. The addition of neutrophils to HUVEC pretreated with Escherichia coli endotoxin, ILI or TNF resulted in a further reduction in both cellular GAGS and surface anionic sites. These results suggest that changes in endothelial cell GAG metabolism during inflammation may contribute to the disturbance of vascular endothelial homeostasis associated with infectious and inflammatory states.
Eighty inpatients with established osteoarthrosis received either 1.5 gm of glucosamine sulfate or placebo daily, in three divided oral doses, for 30 days. Articular pain, joint tenderness and swelling, and restriction of active and passive movements were scored at one-week intervals, as were possible side reactions. Hematologic analysis, urine analysis, and occult blood in feces were recorded before and after treatment. Samples of articular cartilage from two patients of each group and from one healthy subject were submitted to scanning electron microscopy after the end of treatment. All symptoms decreased in both groups. The patients treated with glucosamine sulfate experienced a reduction in overall symptoms that was almost twice as large (73% vs. 41%) and twice as fast (time to reduce symptoms by 50%: 20 days vs. 36 days) as those who had placebo. The improvement of autonomous mobility was relatively less, compared to improvement in the other symptoms, for patients with placebo; with glucosamine sulfate, on the contrary, the improvement was as great and as fast as that of the other symptoms. Thus a direct action of glucosamine sulfate on the cartilage is hypothesized. This hypothesis is supported by the findings of electron microscopy. The patients who had placebo showed a typical picture of established osteoarthrosis. Those who had glucosamine sulfate showed a picture more similar to healthy cartilage. It is concluded that glucosamine sulfate tends to rebuild the damaged cartilage, thus restoring articular function in most chronic arthrosic patients.
The pathogenesis of fibrotic disorders is similar regardless of the tissues involved. Inflammatory leukocytes infiltrate the site triggered by chemotactic and activating mediators. This is followed by the elaboration of cytokines that directly and indirectly induce the proliferation of fibroblasts and endothelial cells and the deposition of extracellular matrix (ECM). In the absence of inhibitory signals, the continued production of these mediators sustains the connective tissue accumulation, which results in permanent alteration in tissue structure and function.
This study determined the location and tissue density of cells immunoreactive for tumour necrosis factor alpha (TNF alpha) in intestinal specimens from 24 patients with chronic inflammatory bowel disease (15 with Crohn's disease, nine with ulcerative colitis) and 11 controls. There was significantly increased density of TNF alpha immunoreactive cells in the lamina propria of both ulcerative colitis and Crohn's disease specimens, although the distribution of these cells differed in the two conditions. In ulcerative colitis most of the TNF alpha immunoreactivity was seen in the subepithelial macrophages, with comparatively less in the deep lamina propria, while in Crohn's disease immunoreactive cells were distributed evenly throughout the lamina propria. Increased submucosal immunoreactivity was found only in Crohn's disease, in which TNF alpha positive macrophages tended to cluster around arterioles and venules, often infiltrating and disrupting vascular endothelium. It is suggested that this degree of TNF alpha production probably contributes significantly to the pathogenesis of both Crohn's disease and ulcerative colitis, by impairing the integrity of epithelial and endothelial membranes, increasing inflammatory cell recruitment, and by prothrombotic effects on the vascular endothelium.
Proteoglycans, consisting of glycosaminoglycan (GAG) side chains covalently linked to a protein core, are a major component of the extracellular matrix of the intestinal lamina propria.
This study investigated the effects of lamina propria T cell activation on the proteoglycan component of the matrix.
The high degree of sulphation of GAGs means that they are polyanionic and thus can be visualised in tissue sections by means of colloidal-gold labelled cationic probes.
In human fetal small intestine there is a dense meshwork of anionic residues in the lamina propria and basement membrane. When explants of human fetal small intestine are cultured ex vivo, and resident lamina propria T cells are activated with pokeweed mitogen, mucosal destruction occurs within three days. This is associated with the rapid loss of anionic sites from the lamina propria. Dermatan sulphate proteoglycan is lost from the tissue and is present at increased concentrations in the organ culture supernatants, indicating that T cell activation has led to solubilisation of lamina propria proteoglycans. Tissue destruction and loss of anionic residues are inhibited in a dose dependent fashion by dexamethasone, and by the protease inhibitor, alpha 2 macroglobulin.
Proteolytic degradation of the lamina propria may therefore be a mechanism by which T cell hypersensitivity injures the intestinal mucosa.
Anti-TNF-alpha Ab therapy has been shown to be of benefit in the treatment of active Crohn's disease, but the tissue-injuring processes in the gut mediated by TNF-alpha that might be inhibited by neutralizing Ab are unknown. In this work, we have used a p55 TNF receptor-human IgG fusion protein (TNFR-IgG) to prevent the severe mucosal injury that ensues when lamina propria T cells in explant cultures of human fetal small intestine are directly activated with the lectin PWM. Following T cell activation and associated with mucosal injury, there is a marked elevation of soluble TNF-alpha in organ culture supernatants and a large increase in TNF-alpha mRNA transcripts. The addition of TNFR-IgG at the onset of cultures greatly reduced PWM-induced tissue injury, without inhibiting the increase in TNF-alpha and IFN-gamma transcripts seen following T cell activation. Mucosal injury in this model is mediated by endogenously-produced matrix metalloproteinases (MMPs). When TNFR-IgG was added to PWM-stimulated explants, there was a reduction in MMPs in the explant culture supernatants, especially stromelysin-1. Recombinant TNF-alpha and IL-1beta added directly to mucosal mesenchymal cell lines also caused an increase in MMP production, but only the former was inhibited by the TNFR-IgG. These results suggest that one of the ways in which TNF-alpha causes tissue injury in the gut is by stimulating mucosal mesenchymal cell to secrete matrix-degrading metalloproteinases. Neutralization of this activity should help maintain tissue integrity.
Proteoglycans (PGs) can influence cell behaviors through binding events mediated by their glycosaminoglycan (GAG) chains. This report demonstrates that chondroitin sulfate B, also known as dermatan sulfate (DS), a major GAG released during the inflammatory phase of wound repair, directly activates cells at the physiologic concentrations of DS found in wounds. Cultured human dermal microvascular endothelial cells exposed to DS responded with rapid nuclear translocation of nuclear factor-kappaB (NF-kappaB), increased expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, and increased ICAM-1 cell surface protein. Heparan sulfate and chondroitin sulfates A and C had no effect on activation of NF-kappaB or induction of ICAM-1. Inhibition of NF-kappaB activation blocked the effect of DS. The increase in cell surface ICAM-1 did not involve TNF-alpha or IL-1 release by endothelial cells, but it was facilitated by autocrine factors whose release was initiated by DS. The ICAM-1-inductive activity of DS was confirmed in vivo. Injection of DS, but not heparin or other chondroitin sulfates, into mice greatly increased circulating levels of soluble ICAM. These data provide evidence that DS, but not other GAGs, initiates a previously unrecognized cell signaling event that can act during the response to injury.
Degradation of the extracellular matrix and ulceration of the mucosa are major features of inflammatory bowel disease (IBD). One of the most important enzymes in degrading the matrix and produced in excess by cytokine activated stromal cells, is stromelysin-1. The activity of stromelysin-1 is controlled by tissue inhibitor of metalloproteinase (TIMP-1), its natural inhibitor. In model systems excess stromelysin-1 produces mucosal degradation.
Quantitative competitive RT-PCR was used to analyse stromelysin-1 and TIMP-1 transcripts; western blotting was used to measure the amount of stromelysin-1 and TIMP-1 protein in biopsy samples from children with IBD.
In biopsies from patients with active Crohn's disease (n=24), ulcerative colitis (n=23), and controls (n=16), TIMP-1 transcripts and protein were abundant and unchanged. Stromelysin-1 transcripts and protein were markedly elevated in mucosal biopsies obtained from inflamed sites of patients with active IBD but were not elevated in adjacent endoscopically normal mucosa (n=10). Elevated levels of stromelysin-1 transcripts in active Crohn's disease (n=5) returned to normal levels following treatment with enteral nutrition.
Stromelysin-1 is markedly overexpressed at inflamed sites in patients with IBD whereas TIMP-1 remains unaltered. Excess stromelysin-1 is likely to be responsible for loss of mucosal integrity in IBD.
The pathogenesis of fibrotic disorders is similar regardless of the tissues involved. Inflammatory leukocytes infiltrate the site triggered by chemotactic and activating mediators. This is followed by the elaboration of cytokines that directly and indirectly induce the proliferation of fibroblasts and endothelial cells and the deposition of extracellular matrix (ECM). In the absence of inhibitory signals, the continued production of these mediators sustains the connective tissue accumulation, which results in permanent alteration in tissue structure and function.
Anti-tumor necrosis factor alpha monoclonal antibody treatment (infliximab) reduces clinical signs and symptoms in patients with Crohn's disease. The effects of infliximab on mucosal histopathologic abnormalities in Crohn's ileocolitis were studied.
Thirteen patients with steroid-refractory Crohn's disease were treated with a single infusion of infliximab (5-20 mg/kg), and 5 were treated with placebo. Ileal and colonic biopsy specimens of all patients were collected before and 4 weeks after therapy. Severity of inflammation was assessed by a histological score. Immunohistochemical stainings with antibodies against HLA-DR, CD68, tumor necrosis factor alpha, intercellular adhesion molecule 1, lymphocyte function-associated antigen, CD4, CD8, and interleukin 4 were performed.
Total histological activity score was reduced significantly in both ileitis and colitis after infliximab. This is caused by a virtual disappearance of the neutrophils and a reduction of mononuclear cells. Mucosal architecture returned to normal in 4 patients at 4 weeks. The number of lamina propria mononuclear cells decreased because of a global reduction of CD4(+) and CD8(+) T lymphocytes and CD68(+) monocytes. Aberrant colonic epithelial HLA-DR expression completely disappeared. The percentage of intercellular adhesion molecule 1 and lymphocyte function-associated antigen 1-expressing and interleukin 4- and tumor necrosis factor-positive lamina propria mononuclear cells sharply decreased.
Infliximab dramatically decreases histological disease activity in Crohn's ileocolitis. Signs of active inflammation nearly disappear accompanied by a profound down-regulation of mucosal inflammatory mediators.
Glucosamine synthetase is the first enzyme in glycoprotein biosynthesis, catalysing the formation of glucosamine-6-phosphate, from which N-acetylglucosamine is formed. The levels of this enzyme in normal human colonic mucosa (in colectomy specimens and rectal biopsies) were found to be 13-8 +/- 4-0 micron mol glucosamine synthesised/h/g wet wt. In the colonic mucosa in ulcerative colitis and Crohn's colitis the enzyme level was diminished when there was loss of epithelial cells in the mucosa, although not when there was just loss of goblet cells. In patients recovering from an acute attack of ulcerative colitis, the enzyme levels rose to a peak above the normal range, an effect which did not occur in patients who did not recover promptly. This recovery peak may be related to the synthesis of gastrointestinal mucus, or immunoglobulin, or the secretory component of IgA, all of which contain large amounts of N-acetylglucosamine.
This study shows that N-acetyl-galactosamine and N-acetyl-glucosamine can diminish the production of superoxide anion from cytochalasin-B treated PMNs stimulated with FMLP. Inhibition ranged from 80.9% to 1.8%. N-acetyl-galactosamine was superior to N-acetyl-glucosamine, but both showed their action in a dose-related fashion. The mannosamine may diminish the superoxide production, but without a statistical significance. Other sugars such as L-fucose, D-fucose and D-glucose failed to induce inhibition of superoxide generation. Previous reports showed that sugars interfere with carbohydrates lectins interaction. This study shows that aminosugars can do more than interfere with carbohydrates-lectin interaction. The mechanism is not completely known yet. The question whether aminosugars affect cell-cell interaction, regulation of respiratory burst, inflammatory mediators functions, or the glucose uptake and utilization needs further study.
Wheat flour and other cereals toxic for celiac patients contain an alcohol-soluble protein fraction that, under experimental conditions simulating in vivo protein digestion, yields peptides that agglutinate undifferentiated K 562(S) cells. In contrast, cereals well tolerated in celiac disease (i.e., rice and maize) do not. Furthermore, purified A-gliadin peptides that damage in vitro-cultured flat celiac mucosa are powerful agglutinins for K 562(S) cells, whereas A-gliadin peptides that do not show any adverse in vitro effect on celiac intestine lack agglutinating activity. Mannan, acetylglucosamine, and its oligomers (N,N'-diacetylchitobiose and N,N',N"-triacetylchitotriose) were able to prevent and reverse cell agglutination induced by peptides from all the toxic cereals. Moreover, mannan and N,N',N"-triacetylchitotriose exhibited a protective effect on intestinal mucosa specimens of patients with active celiac disease cultured with wheat protein-derived peptides. These data are consistent with the hypothesis that the agglutinating and toxic peptides are bound by carbohydrates.
Evidence is accumulating that colonic mucin glycoconjugates are altered in ulcerative colitis. In order to investigate this further, the lectin-binding properties of rectal glycoconjugates have been studied in ulcerative colitis, Crohn's disease, and controls using lectin-peroxidase histochemistry. Ten lectins were used including peanut agglutinin (PNA) which is known to bind to malignant and adenomatous but not normal colonic mucins. Eight of 21 ulcerative colitis rectal biopsies and 10 of 17 Crohn's disease rectal biopsies showed PNA positivity, particularly in the supranuclear region of surface epithelial cells. There was no correlation between PNA positivity and duration of disease or inflammation, and none of the biopsies showed evidence of dysplasia. This abnormality in epithelial cell glycoconjugates seems to be commonly present in nondysplastic mucosa and occurs in both ulcerative colitis and Crohn's disease. It may reflect a fundamental abnormality in mucus glycoprotein synthesis in inflammatory bowel disease.
The synthesis of glycoproteins was investigated in intestinal mucosa from patients with inflammatory bowel disease (IBD) and from those with various other conditions. The incorporation into acid-insoluble macromolecules of the amino sugar glucosamine, the first and committed metabolite in the biosynthetic sequence, and its immediate derivative, N-acetyl glucosamine was determined. Tissue was incubated with 1-2 nmol 14C-glucosamine and 3H-N-acetyl glucosamine and the simultaneous incorporation of both isotopes was measured. Bowel tissue from areas microscopically uninvolved in active disease process was examined. Values for the incorporation of both substrates into acid-soluble constituents were similar for both IBD and non-IBD groups, as was also the incorporation of 3H into acid-insoluble constituents. The incorporation of 14C, however, when expressed relative to that of 3H in each individual patient, i.e., 14C/3H, was distinctly different in IBD cases. In 26 non-IBD samples this ratio ranged from 0.04-0.26 with a mean of 0.097 +/- 0.009. In nine cases of Crohn's disease values ranged from 0.013-0.06 with a mean of 0.039 +/- 0.011 (p less than 0.01); in nine cases of ulcerative colitis values were 0.007-0.06 with a mean of 0.031 +/- 0.006 (p less than 0.01). It is concluded that the step involving the N-acetylation of the amino sugar is relatively deficient in patients with IBD and this could reduce the synthesis of the glycoprotein cover which protects the mucosa from damage by bowel contents.
Long-term continuous ambulatory peritoneal dialysis (CAPD) frequently induces progressive structural changes in the peritoneal membrane, leading to dialysis failure. Because heparin and glycosaminoglycans favourably remodel anatomical barriers exposed to injury, we studied the effect of intraperitoneal administration of glycosaminoglycans on peritoneal dialysis efficiency. 16 CAPD patients received glycosaminoglycans for 30 days followed by a 30-day wash-out. Glycosaminoglycans in urea and creatinine dialysate-to-plasma ratios significantly increased (means 0.86 and 0.78 at baseline, 0.92 and 0.82 at 30 days, respectively). Peritoneal protein loss was reduced, and serum albumin concentration increased. We now need to assess whether glycosaminoglycans can postpone dialysis failure in the long term.
This review article highlights the evidence supporting the concept that, like lymphocytes, fibroblasts also consist of subpopulations with unique phenotypes and functions. A new view of the fibroblast is that they are dynamic and consist of subsets which produce cytokines and interact with the immune system. For example, murine lung fibroblasts separated by fluorescence-activated cell sorting on the basis of the thymocyte-1 antigen are heterogeneous in their morphology, expression of surface markers, antigen presentation to T lymphocytes, ability to synthesize collagen, and cytokine production. Human lung fibroblasts have also been found to be heterogeneous in surface marker expression, proliferation, and collagen production. Investigation of pulmonary fibroblast heterogeneity is important since the lung is particularly susceptible to fibrosis induced by chemotherapy and radiation, inhaled particles, systemic autoimmune disease, etc. The inflammatory responses which typically precede fibrotic induction may be controlled by a subset of resident fibroblasts. Another subset may be important for the fibroblast hyperplasia and extensive extracellular matrix production which are hallmarks of fibrosis. In another model system, periodontal fibroblasts, namely those from periodontal ligament (PDL) and gingiva, also reveal heterogeneity. For example, PDL fibroblasts are composed of subpopulations based on collagen production, morphology, and glycogen pools. Subsets of gingival fibroblasts have also been obtained based on receptors for cyclosporin A and C1q. Specific fibroblast subsets may be involved in gingival repair and hyperplasia. Studies comparing fibroblasts from normal skin vs skin involved with scleroderma have found that scleroderma fibroblasts are activated and able to participate in an inflammatory response. How these fibroblasts become activated is unclear, but it is believed that a subset of fibroblasts is selectively recruited by cytokines at the inflammation site. Finally, investigation and identification of fibroblast subsets from various tissues and their interaction with the immune system could lead to strategies to prevent or reverse debilitating and potentially fatal fibrotic development.
Gelatinases, belonging to the matrix metalloproteases, contribute to tissue destruction in inflammatory demyelinating disorders of the central nervous system such as multiple sclerosis. We used experimental autoimmune encephalomyelitis (EAE) as an animal model to evaluate the effect of a hydroxamate matrix metalloprotease inhibitor (GM 6001) on inflammatory demyelination. A single dose of the inhibitor, given intraperitoneally, provided sufficient levels in the cerebrospinal fluid of animals with EAE to induce at least a partial inhibition of the gelatinase activity in the cerebrospinal fluid. When administered daily either from the time of disease induction or from the onset of clinical signs, GM 6001 suppressed the development or reversed clinical EAE in a dose-dependent way, respectively. Animals returned to the same clinical course as the nontreated group after cessation of treatment. Animals treated from the onset of clinical signs had normal permeability of the blood-brain barrier, compared with the enhanced permeability in nontreated animals. These results indicate that matrix metalloprotease inhibition can reverse ongoing EAE. This effect appears to be mediated mainly through restoration of the damaged blood-brain barrier in the inflammatory phase of the disease, since, the degree of demyelination and inflammation did not differ between the treatment groups.
We have studied the distribution and nature of sulphated glycosaminoglycans (GAGs) within normal and inflamed intestine. There is increasing evidence that these negatively charged polysaccharides, which both regulate the ability of albumin to leave the vasculature and inhibit thrombosis, may be affected by inflammatory cells and their products. We obtained samples of freshly resected intestinal tissue from eight controls, eleven patients with Crohn's disease, and six with ulcerative colitis. Sulphated GAGs were detected by means of a gold-conjugated poly-L-lysine probe, and the tissue density of anionic sites was assessed semiquantitatively by means of a Lennox graticule. In normal intestine there was staining in the vascular endothelium and the subepithelial basal lamina and throughout the extracellular matrix of the lamina propria and submucosa. Tissue from the patients with inflammatory bowel disease showed inflammation macroscopically and on histology. There were profound abnormalities of extracellular matrix GAGs, limited to the mucosa in ulcerative colitis and greatest in the submucosa in Crohn's disease. There was also substantial loss of GAGs from the subepithelial basal lamina in both disorders and from the vascular endothelium in submucosa in Crohn's disease. The extent of local GAG disruption was associated with the distribution of macrophages immunoreactive for tumour necrosis factor alpha and the activation marker RM 3/1. We suggest that inflammatory disruption of vascular and connective tissue GAGs may be an important pathogenetic mechanism, contributing to the leakage of protein and fluid, thrombosis, and tissue remodelling seen in inflammatory bowel disease.
Abnormalities in colonic glycoprotein synthesis have been implicated in the pathogenesis of ulcerative colitis and Crohn's disease. Glucosamine synthetase is the rate-limiting step in the biosynthesis of gastrointestinal glycoprotein and has been measured in control subjects (N = 23) and patients with ulcerative colitis (N = 26) or Crohn's disease of the colon (N = 20) classified according to the macroscopic status of the rectum. Glucosamine synthetase activity was relatively constant around the normal colon but lower levels were found in the terminal ileum. In ulcerative colitis, glucosamine synthetase activity was similar to controls (24.0 +/- 1.9) mmol/g wet (wt/hr) irrespective of disease activity (quiescent: N = 13, = 27.3 +/- 1.9; active N = 16, = 26.2 +/- 2.3). Rectal glucosamine synthetase activity was normal in the presence of active Crohn's proctocolitis (29.4 +/- 3.1) but raised in patients with Crohn's colitis and rectal sparing (37.2 +/- 4.9 P < 0.02). Glucosamine synthetase activity was strongly influence by the degree of epithelial preservation.
Cytokines are thought to be important in mediating tissue damage in inflammatory bowel disease (IBD). Many of the in vivo activities of tumor necrosis factor alpha (TNF-alpha) match the changes found in IBD, but its importance is controversial.
A sensitive, reverse hemolytic plaque assay was used to determine the frequency of TNF-alpha secreting cells isolated from mucosal biopsy specimens of children with Crohn's disease or ulcerative colitis (UC) and non-IBD controls before and after medical treatment.
Frequency of TNF-alpha secreting cells was significantly increased in biopsy specimens from children with mild, nonspecific inflammation compared with those with histologically normal intestine. Frequency did not increase in UC compared with children with nonspecific inflammation but was significantly greater in Crohn's disease than in UC. After treatment, the frequency of TNF-alpha secreting cells was reduced in patients receiving cyclosporin A, not reduced in patients with steroids or enteral nutrition, and not changed with treatment in UC.
TNF-alpha secreting cells are increased in the mucosa of inflamed intestine, regardless of pathogenesis. In patients with IBD, higher levels are seen in Crohn's disease than in UC, probably reflecting the extensive T-cell activation in Crohn's disease. No relation existed between histological healing and the frequency of TNF-alpha-secreting cells.
Scatter factor (SF), a cell motility factor with a multimodular structure, is identical to hepatocyte growth factor (HGF), a potent mitogen of various cell types. The receptor for SF/HGF has recently been identified as the c-Met proto-oncogene product, a transmembrane receptor tyrosine kinase. Depending on the target cells and culture conditions, SF/HGF has several distinct activities in vitro, i.e., it induces cell motility, proliferation, invasiveness, tubular morphogenesis, angiogenesis, or cytotoxicity. In vivo, SF/HGF might be involved in tissue regeneration, tumor progression, and embryological processes.
Proteoglycans (PGs) and lung hyaluronan (HA) are important components of the lung matrix both during normal development and in response to injury. We combined morphologic and biochemical techniques to study changes in PG and HA in a developmental series of Macaca nemestrina lungs ranging from 62% gestation to 3 mo post-term (n = 16), in adult lungs (n = 6), and from prematurely delivered, mechanically ventilated monkeys with hyaline membrane disease (HMD) (n = 7). Three groups of cuprolinic blue-positive (CuB) precipitates, identified by size, location, and susceptibility to enzyme digestion were found in lungs from all animals. Immature alveolar interstitium is characterized by loosely woven collagen bundles and an abundance of large (100 to 200 nm) stained filaments representing chondroitin sulfate proteoglycans (CSPGs). As maturation proceeds, the interstitial matrix appears increasingly organized, with large collagen bundles associated with 20 nm CuB-stained deposits (dermatan sulfate proteoglycans, DSPGs), and fewer large CSPGs. Fetal alveolar basement membrane contains CuB-stained heparin sulfate proteoglycans (HSPGs) (10 nm) scattered throughout. Lung matrix from animals with HMD appeared to have a disruption of the collagen-DSPG relationship, in addition to an enrichment in large CSPG. Complementary biochemical analysis of lung PGs and HA was done. Minced lung parenchyma was cultured with [3H]-glucosamine and [35S]-sulfate for 24 h; PGs and HA were extracted and analyzed. While PG synthesis during development tended to be highest at 80% gestation, animals with HMD showed greatly increased synthesis, approximately 2.5-fold higher than comparable fetal animals. In the developmental series, [3H]-glucosamine incorporation into HA was maximal at term, falling abruptly thereafter. HMD animals, however, showed a 2.3-fold increase over controls in net HA synthesis. Extracted PGs were separated according to buoyant density by dissociative cesium chloride density gradient ultracentrifugation. Two peaks of 35S-labeled PGs were separated from each density gradient fraction by chromatography on Sepharose CL-4B. A large CSPG was the principal PG eluting in the voiding volume, while the second broad peak (K(av) = 0.42) contained a mixed population of CSPG, DSPG, and HSPGs, the proportions of which varied with age. Both ultrastructural and biochemical analyses indicate that production of a large, high buoyant density CSPG predominates in fetal lung tissue, and diminishes with developmental age. Synthesis of large CSPG is greatly increased in lung explants from prematurely delivered animals with HMD.(ABSTRACT TRUNCATED AT 400 WORDS)
Postoperative abdominal adhesions are associated with numerous complications, including small bowel obstruction, difficult and dangerous reoperations, and infertility. A sodium hyaluronate and carboxymethylcellulose bioresorbable membrane (HA membrane) was developed to reduce formation of postoperative adhesions. The objectives of our prospective study were to assess the incidence of adhesions that recurred after a standardized major abdominal operation using direct laparoscopic peritoneal imaging and to determine the safety and effectiveness of HA membrane in preventing postoperative adhesions.
Eleven centers enrolled 183 patients with ulcerative colitis or familial polyposis who were scheduled for colectomy and ileal pouch-anal anastomosis with diverting-loop ileostomy. Before abdominal closure, patients were randomly assigned to receive or not receive HA membrane placed under the midline incision. At ileostomy closure eight to 12 weeks later, laparoscopy was used to evaluate the incidence, extent, and severity of adhesion formation to the midline incision.
Data were analyzed for 175 assessable patients. While only five (6 percent) of 90 control patients had no adhesions, 43 (51 percent) of 85 patients receiving HA membrane were free of adhesions (p < 0.00000000001). The mean percent of the incision length involved was 63 percent in the control group, significantly greater than the 23 percent observed in patients who received HA membrane (p < 0.001). Dense adhesions were observed in 52 (58 percent) of the 90 control patients, but in only 13 (15 percent) of the 85 receiving HA membrane (P < 0.0001). Comparison of the incidence of specific adverse events between the groups did not identify a difference (P > 0.05).
This study represents the first controlled, prospective evaluation of postoperative abdominal adhesion formation and prevention after general abdominal surgery using standardized, direct peritoneal visualization. In this study, HA membrane was safe and significantly reduced the incidence, extent, and severity of postoperative abdominal adhesions.
Although progression to pulmonary fibrosis in preterm infants with respiratory distress syndrome (RDS) is related to the inflammatory response, the nature of this response remains controversial. We have therefore performed sequential bronchoalveolar lavages in 30 infants with RDS (13 of whom developed bronchopulmonary dysplasia) and 7 ventilated control infants, characterizing the cells obtained by immunohistochemical analysis of lineage-specific markers and assaying macrophage-associated chemokines and cytokines in supernatant fluid. At all ages from birth, lavage supernatants demonstrated highly significant increase over controls of the beta-chemokine macrophage inflammatory protein (MIP)-1 alpha, although not of regulated upon activation, normal T cell expressed and secreted (RANTES), of the cytokines tumor necrosis factor (TNF)-alpha and IL-1 beta, and of elastase/alpha-1 antitrypsin. Significantly higher concentrations of MIP-1 alpha in particular were associated with the later development of fibrosis. Increased numbers of macrophages expressing the activation marker RM/3-1 were found at all ages in bronchopulmonary dysplasic infants, whereas neutrophil numbers were increased from d 3. Dexamethasone administered to 10 infants induced rapid decrease in inflammatory cell numbers and concentrations of MIP-1 alpha, tumor necrosis factor-alpha, IL-1 beta, and elastase/alpha-1 antitrypsin. The inflammatory response in neonatal RDS begins within the first day of life. Long-term outcome is associated with the magnitude of this early response, in particular production of MIP-1 alpha. The early introduction of specific therapy is thus likely to be beneficial.
Many of the clinicopathologic features of neonatal respiratory distress syndrome (RDS) may be related to the inflammatory response mounted by the affected infant, although little is known about the interstitial component of this response. We have thus studied the local inflammatory response in this condition by immunohistochemical analysis of whole lung lobes, obtained at postmortem from 40 infants who died from acute RDS in the first week of life. All had demonstrated classical clinical history and histologic features. An archival subgroup from the early 1970s had never received ventilatory support. Immunohistochemical analysis demonstrated rapid temporal increase from birth in the mucosal density of CD68+ macrophages, MAC-387+ monocytes/macrophages, polymorphonuclear neutrophils, and tumor necrosis factor-alpha-immunoreactive cells, maximal in those dying at or after 72 h. Using a cationic probe specific for sulfated glycosaminoglycans (GAGs), the inflammatory infiltration was seen to be associated with striking loss of endothelial, basement membrane, and interstitial GAGs, which was almost complete by 48-72 h. GAG degradation products were found within hyaline membranes in all infants dying after 48 h. This study confirms that neonatal RDS is characterized by intense interstitial inflammation, significantly underestimated on routine staining. This begins within hours of birth and is maximal by 72 h of age. Breakdown of sulfated GAGs within the extracellular matrix follows the same time course and may explain much of the physiologic derangement characteristic of this condition.
Glucosamine and its derivatives, such as glucosamine sulfate and N-acetyl-D-glucosamine (NAG), have been shown to be effective in the treatment of patients with osteoarthritis. Unfortunately, the half-life of glucosamine in the blood is relatively short; therefore, a sustained-release form of the compound would be highly desirable. The purpose of this pilot study was to determine whether the polymeric form of NAG (POLY-Nag) could provide a longer-lasting oral source of NAG. Ten healthy subjects each ingested 1 g/d of either NAG or POLY-Nag for 3 days. After a 4-day washout period, each subject was crossed over to receive the other compound for 3 days. Serum samples were collected and analyzed using high-performance liquid chromatography. Results show that orally ingested NAG and POLY-Nag are absorbed, resulting in increased serum levels of NAG, and POLY-Nag appears to be at least as effective as NAG. Serum levels of NAG had decreased by 48 hours after cessation of ingestion of NAG or POLY-Nag but were still above baseline levels. Increases in serum glucosamine levels indicate that NAG and POLY-Nag are converted to glucosamine in vivo. In conclusion, POLY-Nag may provide a source of serum glucosamine for treatment of patients with osteoarthritis. Longer and more rigorous pharmaco-kinetic and clinical studies need to be done.