Glucosamine regulation of LPS-mediated inflammation in human bronchial epithelial cells

Validation of a physiological type 2 diabetes model in human periodontal ligament stem cells

OBJECTIVES

Type 2 diabetes (T2DM), a recognized risk factor for periodontitis, is characterized by insulin resistance. However, the molecular mechanisms concerning the role of insulin resistance in linking T2DM and periodontitis remain poorly elucidated due to the absence of an appropriate T2DM cell model. We aimed to explore an appropriate model of T2DM in human periodontal ligament stem cells (hPDLSCs) and uncover the involved mechanisms.

MATERIALS AND METHODS

hPDLSCs were incubated with common reagents for recapitulating insulin resistance state including high glucose (HG) (15, 25, 35, 45 mM), glucosamine (0.8, 8, 18, 28, 38 mM), or palmitic acid (PA; 100, 200, 400, 800 μM), combined with LPS for 48 h. The insulin signaling pathway, inflammation, and pyroptosis were detected by western blots and quantitative real-time polymerase chain reaction (RT-qPCR). The effects on osteogenesis were evaluated by alkaline phosphatase staining, alizarin red S staining, RT-qPCR, and western blots.

RESULTS

HG failed to recapitulate insulin resistance. Glucosamine was sufficient to induce insulin resistance but failed to trigger inflammation. In total, 100 and 200 μM PA exhibited the most proinflammatory, insulin resistance, and pyroptosis induced role, and inhibited the osteogenic differentiation of hPDLSCs.

CONCLUSION

Palmitic acid is a promising candidate for developing T2DM model in hPDLSCs.

Glucosamine and Chondroitin Use and Mortality Among Adults in the United States from 1999 to 2014

Introduction: Glucosamine and chondroitin are supplements that are often, but not always, used in combination for arthritis and joint pain. Multiple studies have suggested that glucosamine and chondroitin may be associated with reduced risk of several diseases, as well as all-cause, cancer- and respiratory disease-specific mortality. Methods: Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) were used to further evaluate the association between glucosamine and chondroitin with mortality. Participants include 38,021 adults, ages 20+ years and older, who completed the detailed NHANES between 1999 and 2014. Participants were followed for death through linkage with the National Death Index through the end of 2015, over which time 4905 deaths occurred. Adjusted hazard ratios (HRs) for overall and cause-specific mortality were estimated using Cox regression models. Results: Despite glucosamine and chondroitin use appearing to be inversely associated with mortality in the minimally adjusted models, no association was observed in multivariable models (glucosamine: HR = 1.02; 95% confidence interval [CI]: 0.86-1.21, chondroitin: HR = 1.04, 95% CI: 0.87-1.25). No association with cancer mortality or other mortality rate was observed after multivariable adjustment. There was a suggestive, nonsignificant inverse association for cardiovascular-specific mortality (glucosamine HR = 0.72; 95% CI: 0.46-1.15, chondroitin: HR = 0.76; 95% CI: 0.47-1.21). Conclusion: The lack of significant relationship between glucosamine and chondroitin use and all-cause or cause-specific mortality after adjusting extensively for multiple covariates in this nationally representative adult population was in contrast to prior literature. Given the limited power to explore the cause-specific mortality, future well-powered studies will be needed to better understand the potential association with cardiovascular-specific mortality.

Commensal bacteria of the lung microbiota synergistically inhibit inflammation in a three-dimensional epithelial cell model

Patients with chronic lung disease suffer from persistent inflammation and are typically colonized by pro-inflammatory pathogenic bacteria. Besides these pathogens, a wide variety of commensal species is present in the lower airways but their role in inflammation is unclear. Here, we show that the lung microbiota contains several species able to inhibit activation of the pro-inflammatory NF-κB pathway and production of interleukin 8 (IL-8), triggered by lipopolysaccharide (LPS) or H₂O₂, in a physiologically relevant three-dimensional (3D) lung epithelial cell model. We demonstrate that the minimal dose needed for anti-inflammatory activity differs between species (with the lowest dose needed for Rothia mucilaginosa), and depends on the type of pro-inflammatory stimulus and read out. Furthermore, we evaluated synergistic activity between pairs of anti-inflammatory bacteria on the inhibition of the NF-κB pathway and IL-8 secretion. Synergistic anti-inflammatory activity was observed for 4/10 tested consortia. These findings indicate that various microbiota members can influence lung inflammation either alone or as a consortium. This information can contribute to a better understanding of the lung microbiota in chronic lung disease development and process, and could open up new avenues for treatment.

Impact of health and lifestyle food supplements on periodontal tissues and health

According to the new classification, periodontitis is defined as a chronic multifactorial inflammatory disease associated with dysbiotic biofilms and characterized by progressive destruction of the tooth-supporting apparatus. This definition, based on the current scientific evidence, clearly indicates and emphasizes, beside the microbial component dental biofilm, the importance of the inflammatory reaction in the progressive destruction of periodontal tissues. The idea to modulate this inflammatory reaction in order to decrease or even cease the progressive destruction was, therefore, a logical consequence. Attempts to achieve this goal involve various kinds of anti-inflammatory drugs or medications. However, there is also an increasing effort in using food supplements or so-called natural food ingredients to modulate patients' immune responses and maybe even improve the healing of periodontal tissues. The aim of this chapter of Periodontology 2000 is to review the evidence of various food supplements and ingredients regarding their possible effects on periodontal inflammation and wound healing. This review may help researchers and clinicians to evaluate the current evidence and to stimulate further research in this area.

Glucosamine Use and Risk of Colorectal Cancer: Results from UK Biobank

BACKGROUND

Use of the dietary supplement glucosamine has been associated with reduced risk of colorectal cancer (CRC); however, it remains unclear if the association varies by screening status, time, and other factors.

METHODS

We therefore evaluated these questions in UK Biobank. Multivariable-adjusted Hazard Ratios (HRs) and 95% Confidence Intervals (95% CI) were estimated using Cox proportional hazards regression.

RESULTS

No association was observed between use of glucosamine and risk of CRC overall (HR: 0.94; 95% CI: 0.85-1.04). However, the association varied by screening status (p-interaction:0.05), with an inverse association observed only among never-screened individuals (HR: 0.86; 95% CI: 0.76-0.98). When stratified by study time, an inverse association was observed in early follow-up among those entering the cohort in early years (2006-2008, HR: 0.80; 95% CI: 0.67-0.95). No heterogeneity was observed by age, sex, body mass index, smoking status, or use of non-steroidal anti-inflammatory drugs.

CONCLUSIONS

While there was no association between glucosamine use and CRC overall, the inverse association among never-screened individuals mirrors our observations in prior exploratory analyses of US cohorts. The National Health Service Bowel Cancer Screening Program started in 2006 in England and was more widely implemented across the UK by 2009. In line with this, we observed an inverse association limited to early follow-up in those surveyed 2006-2008, before screening was widely implemented.

IMPACT

These data suggest that unscreened individuals may benefit from use of glucosamine; however, further studies are needed to confirm the interplay of screening and timing.

Subchronic toxicity evaluation of glucosamine and glucosamine in combination with chondroitin sulfate in obese Zucker rats

D-glucosamine is a widely consumed dietary supplement used to promote joint health and treat osteoarthritis. It also stimulates intracellular hexosamine flux and increases transforming growth factor β1 (TGFβ1) mRNA expression and insulin resistance in animal studies. The effects of D-glucosamine exposure were investigated in obese Zucker rats. Male (leprfa/leprfa) Zucker rats were exposed to 30, 120, 300 and 600 mg D-glucosamine HCl per kg/day either alone or with chondroitin sulfate (24, 96, 240 and 480 mg/kg/day respectively) for 90 days. After 4 weeks exposure, these doses produced CmaxD-glucosamine concentrations of up to 24 μM in tail vein serum concurrent with a transient 30% increase in blood glucose concentration in the 600 mg/kg/day dose group. D-Glucosamine did not significantly alter body weight, blood glucose or serum insulin levels at any dose tested after 13 weeks exposure, but did increase urinary TGFβ1 concentrations. The Zucker rats developed nephropathy and scrotal sores that were related to their hyperglycemia and obesity, and D-glucosamine exposure exacerbated these conditions to a small extent. The incidence of pulmonary osseous metaplasia was increased in rats exposed to D-glucosamine and a single incidence of adrenal osseous metaplasia was noted in one animal exposed to 600/480 mg D-glucosamine HCl/chondroitin sulfate. These lesions may have been treatment related. These studies suggest that the risk of adverse effects of oral D-glucosamine is small compared to that of hyperglycemia in these animals, but the potential for TGFβ1-mediated pathologies, such as osseous metaplasia and renal nephropathy may be increased.

Glucosamine and Chondroitin Use in Relation to C-Reactive Protein Concentration: Results by Supplement Form, Formulation, and Dose

Objectives: Glucosamine and chondroitin supplements have been associated with reduced inflammation, as measured by C-reactive protein (CRP). It is unclear if associations vary by formulation (glucosamine alone vs. glucosamine+chondroitin), form (glucosamine hydrochloride vs. glucosamine sulfate), or dose. Design, Subjects, Setting, Location: The authors evaluated these questions using cross-sectional data collected between 1999 and 2010 on 21,917 US adults, surveyed as part of the National Health and Nutrition Examination Survey (NHANES). Exposures: Glucosamine and chondroitin use was assessed during an in-home interview; exposures include supplement formulation, form, and dose. Outcome/Analysis: CRP was measured using blood collected at interview. Survey-weighted linear regression was used to evaluate the multivariable-adjusted association between exposures and log-transformed CRP. Results: In early years (1999-2004), use of glucosamine (ratio = 0.87; 95% confidence interval [CI] = 0.79-0.96) and chondroitin (ratio = 0.83; 95% CI = 0.72-0.95) was associated with reduced CRP. However, associations significantly varied by calendar time (p-interaction = 0.04 and p-interaction = 0.01, respectively), with associations nonsignificant in later years (ratio = 1.09; 95% CI = 0.94-1.28 and ratio = 1.16; 95% CI = 0.99-1.35, respectively). Consequently, all analyses have been stratified by calendar time. Associations did not significantly differ by formulation in either set of years; however, significant associations were observed for combined use of glucosamine+chondroitin (ratioearly = 0.82; 95% CI = 0.72-0.95; ratiolate = 1.16; 1.00-1.35), but not glucosamine alone. Associations also did not significantly differ by supplement form. Even so, a significant inverse association was observed only for glucosamine sulfate in the early years (ratio = 0.78; 95% CI = 0.64-0.95); no significant association was observed for glucosamine hydrochloride. No significant trends were observed by dose. Conclusions: Although a significant inverse association was observed for glucosamine and chondroitin and CRP in early years, this association did not hold in later years. This pattern held for combined use of glucosamine+chondroitin as well as glucosamine sulfate, although associations did not significantly vary by supplement form, formulation, or dose. Further study is needed to better understand these associations in the context of calendar time.

Nutraceutical Strategies for Suppressing NLRP3 Inflammasome Activation: Pertinence to the Management of COVID-19 and Beyond

Inflammasomes are intracellular protein complexes that form in response to a variety of stress signals and that serve to catalyze the proteolytic conversion of pro-interleukin-1β and pro-interleukin-18 to active interleukin-1β and interleukin-18, central mediators of the inflammatory response; inflammasomes can also promote a type of cell death known as pyroptosis. The NLRP3 inflammasome has received the most study and plays an important pathogenic role in a vast range of pathologies associated with inflammation-including atherosclerosis, myocardial infarction, the complications of diabetes, neurological and autoimmune disorders, dry macular degeneration, gout, and the cytokine storm phase of COVID-19. A consideration of the molecular biology underlying inflammasome priming and activation enables the prediction that a range of nutraceuticals may have clinical potential for suppressing inflammasome activity-antioxidants including phycocyanobilin, phase 2 inducers, melatonin, and N-acetylcysteine, the AMPK activator berberine, glucosamine, zinc, and various nutraceuticals that support generation of hydrogen sulfide. Complex nutraceuticals or functional foods featuring a number of these agents may find utility in the prevention and control of a wide range of medical disorders.

Anti-Inflammatory Activity of Chitosan and 5-Amino Salicylic Acid Combinations in Experimental Colitis

Chitosan is used in various drug delivery approaches as a pharmaceutical excipient. Although its potential as an immunomodulatory agent has been reported, its use in this capacity has not been fully explored. The efficacy of chitosan as an active pharmacological agent, particularly in anti-inflammatory therapy in inflammatory bowel diseases (IBD), was investigated in this study. The potential impact of the molecular weight (MW) and degree of deacetylation (DD) of chitosan was investigated together with 5-amino salicylic acid (5-ASA) for its efficacy in a combination anti-inflammatory therapy in murine experimental colitis. Such a combination would potentially be developed into novel dual strategies whereby chitosan acts as a mucoadhesive excipient as well as provide an additional anti-inflammatory benefit. Chitosan grades with different MW and DD were administered intrarectally alone or in combination with 5-ASA to colitis mice for 3 days. Myeloperoxidase (MPO) and alkaline phosphatase (ALP) activity and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and nuclear factor kappa-B (NF-κB) levels were assessed from the colon. Intrarectal treatment of colitis with 30 mg/kg chitosan alone and with 30 mg/kg 5-ASA for 3 days led to a significant decrease in MPO, ALP, TNF-α, IL-6, IL-1β and NF-κB in colitis mice compared to untreated mice. Surprisingly, the efficacy of chitosan as an anti-inflammatory polymer was relatively independent from its structural properties, namely DD and MW. However, combinations of chitosan with 5-ASA showed a significant pharmacological improvement, whereby the additive anti-inflammatory efficacy observed shows the possibility of finetuning chitosan by combining it with anti-inflammatory agents to optimize its anti-inflammatory potential.

Pseudomonas aeruginosa-derived flagellin stimulates IL-6 and IL-8 production in human bronchial epithelial cells: A potential mechanism for progression and exacerbation of COPD

Background and purpose of the study: Pseudomonas aeruginosa commonly colonizes the airway of patients with chronic obstructive pulmonary disease (COPD) and exacerbates their symptoms. P. aeruginosa carries flagellin that stimulates toll-like receptor (TLR)-5; however, the role of flagellin in the pathogenesis of COPD remains unclear. The aim of the study was to evaluate the mechanisms of the flagellin-induced innate immune response in bronchial epithelial cells, and to assess the effects of anti-inflammatory agents for treatment. Materials and methods: We stimulated BEAS-2B cells with P. aeruginosa-derived flagellin, and assessed mRNA expression and protein secretion of interleukin (IL)-6 and IL-8. We also used mitogen-activated protein kinases (MAPK) inhibitors to assess the signaling pathways involved in flagellin stimulation, and investigated the effect of clinically available anti-inflammatory agents against flagellin-induced inflammation. Results: Flagellin promoted protein and mRNA expression of IL-6 and IL-8 in BEAS-2B cells and induced phosphorylation of p38, ERK, and JNK; p38 phosphorylation-induced IL-6 production, while IL-8 production resulted from p38 and ERK phosphorylation. Fluticasone propionate (FP) and dexamethasone (DEX) suppressed IL-6 and IL-8 production in BEAS-2B cells, but clarithromycin (CAM) failed to do so. Conclusions: P. aeruginosa-derived flagellin-induced IL-6 and IL-8 production in bronchial epithelial cells, which partially explains the mechanisms of progression and exacerbation of COPD. Corticosteroids are the most effective treatment for the suppression of flagellin-induced IL-6 and IL-8 production in the bronchial epithelial cells.

Glucosamine use and risk of colorectal cancer: results from the Cancer Prevention Study II Nutrition Cohort

PURPOSE

Use of glucosamine supplements has been associated with reduced risk of colorectal cancer (CRC) in previous studies; however, information on this association remains limited.

METHODS

We examined the association between glucosamine use and CRC risk among 113,067 men and women in the Cancer Prevention Study II Nutrition Cohort. Glucosamine use was first reported in 2001 and updated every 2 years thereafter. Participants were followed from 2001 through June of 2011, during which time 1440 cases of CRC occurred.

RESULTS

As has been observed in prior studies, current use of glucosamine, modeled using a time-varying exposure, was associated with lower risk of CRC (HR 0.83; 95% CI 0.71-0.97) compared to never use. However, for reasons that are unclear, this reduction in risk was observed for shorter-duration use (HR 0.68; 95% CI 0.52-0.87 for current users with ≤ 2 years use) rather than longer-duration use (HR 0.90; 95% CI 0.72-1.13 for current users with 3 to < 6 years of use; HR 0.99; 95% CI 0.76-1.29 for current users with ≥ 6 years of use).

CONCLUSIONS

Further research is needed to better understand the association between glucosamine use and risk of CRC, and how this association may vary by duration of use.

Use of glucosamine and chondroitin supplements in relation to risk of colorectal cancer: Results from the Nurses' Health Study and Health Professionals follow-up study

Recent epidemiologic evidence has emerged to suggest that use of glucosamine and chondroitin supplements may be associated with reduced risk of colorectal cancer (CRC). We therefore evaluated the association between use of these non-vitamin, non-mineral supplements and risk of CRC in two prospective cohorts, the Nurses' Health Study and Health Professionals Follow-up Study. Regular use of glucosamine and chondroitin was first assessed in 2002 and participants were followed until 2010, over which time 672 CRC cases occurred. Cox proportional hazards regression was used to estimate relative risks (RRs) within each cohort, and results were pooled using a random effects meta-analysis. Associations were comparable across cohorts, with a RR of 0.79 (95% CI: 0.63-1.00) observed for any use of glucosamine and a RR of 0.77 (95% CI: 0.59-1.01) observed for any use of chondroitin. Use of glucosamine in the absence of chondroitin was not associated with risk of CRC, whereas use of glucosamine + chondroitin was significantly associated with risk (RR: 0.77; 95% CI: 0.58-0.999). The association between use of glucosamine + chondroitin and risk of CRC did not change markedly when accounting for change in exposure status over follow-up (RR: 0.75; 95% CI: 0.58-0.96), nor did the association significantly vary by sex, aspirin use, body mass index, or physical activity. The association was comparable for cancers of the colon and rectum. Results support a protective association between use of glucosamine and chondroitin and risk of CRC. Further study is needed to better understand the chemopreventive potential of these supplements.

Molecular mechanisms and biomedical applications of glucosamine as a potential multifunctional therapeutic agent

Glucosamine and its acetylated derivative, N-acetyl glucosamine, are naturally occurring amino sugars found in human body. They are important components of glycoproteins, proteoglycans and glycosaminoglycans. Scientific studies have supported that glucosamine has the beneficial pharmacological effects to relieve osteoarthritis symptoms. Glucosamine can also be as a promising candidate for the prevention and/or treatment of some other diseases due to its anti-oxidant and anti-inflammatory activities. Most of its function is exerted by modulation of inflammatory responses especially through Nuclear Factor-κB (NF-κB) that can control inflammatory cytokine production and cell survival. In this review, we present a concise update on additional new therapeutic applications of glucosamine including treatment of cardiovascular disease, neurological deficits, skin disorders, cancer and the molecular mechanistic rationale for these uses. This article will also examine safety profile and adverse effects of glucosamine in human.

Anti-inflammatory effects of orally administered glucosamine oligomer in an experimental model of inflammatory bowel disease

Anti-inflammatory effects of oral administration of the glucosamine oligomers (chito-oligosaccharides: COS) were evaluated in an experimental model of inflammatory bowel disease (IBD). Oral administration of COS improved shortening of colon length and tissue injury (as assessed by histology) in mice. Oral administration of COS inhibited inflammation in the colonic mucosa by suppression of myeloperoxidase activation in inflammatory cells, as well as activation of nuclear factor-kappa B, cyclooxygenase-2, and inducible nitric oxide synthase. Oral administration of COS also reduced serum levels of pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-6). Moreover, it prolonged survival time in mice. These data suggest that COS have anti-inflammatory effects in an experimental model of IBD, and could be new functional foods for IBD patients.

Associations between glucosamine and chondroitin supplement use and biomarkers of systemic inflammation

OBJECTIVES

Glucosamine and chondroitin supplements have been shown to have anti-inflammatory properties in both in vitro studies and animal models; however, little is known about these relationships in humans. The VITamins and Lifestyle (VITAL) biomarker study evaluated the associations between use of these supplements and a panel of circulating inflammatory biomarkers.

DESIGN

Study participants included 217 men and women age 50-75 years living in the Seattle metropolitan area. Use of glucosamine and chondroitin supplements was ascertained by home interview/supplement inventory. Inflammation was assessed by using blood and urine collected at the time of home interview. Measures of systemic inflammation included plasma high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, soluble TNF receptors I and II, and urinary prostaglandin E2-metabolite (PGE-M). Multivariate-adjusted linear regression was used to evaluate the associations between supplement use and biomarkers of inflammation.

RESULTS

High users (14 or more pills/week) of chondroitin had 36% lower hsCRP (ratio, 0.64; 95% confidence interval [CI], 0.39-1.04; p for trend=.03) and 27% lower PGE-M (ratio, 0.73; 95% CI, 0.5-0.98; p for trend=.07) than nonusers. Compared with nonusers, high users of glucosamine had 28% lower hsCRP (ratio, 0.72; 95% CI, 0.47-1.08; p for trend=.09) and 24% lower PGE-M (ratio, 0.76; 95% CI, 0.59-0.97; p for trend=0.10). Use of glucosamine and chondroitin supplements was not associated with the other markers of inflammation.

CONCLUSIONS

These results support prior research suggesting that use of glucosamine and chondroitin is associated with reduced hsCRP and PGE2, but further work is needed to more definitively evaluate the anti-inflammatory potential of these supplements.

Glucosamine attenuates cigarette smoke-induced lung inflammation by inhibiting ROS-sensitive inflammatory signaling

Cigarette smoking causes persistent lung inflammation that is mainly regulated by redox-sensitive pathways. We have reported that cigarette smoke (CS) activates a NADPH oxidase-dependent reactive oxygen species (ROS)-sensitive AMP-activated protein kinase (AMPK) signaling pathway leading to induction of lung inflammation. Glucosamine, a dietary supplement used to treat osteoarthritis, has antioxidant and anti-inflammatory properties. However, whether glucosamine has similar beneficial effects against CS-induced lung inflammation remains unclear. Using a murine model we show that chronic CS exposure for 4 weeks increased lung levels of 4-hydroxynonenal (an oxidative stress biomarker), phospho-AMPK, and macrophage inflammatory protein 2 and induced lung inflammation; all of these CS-induced events were suppressed by chronic treatment with glucosamine. Using human bronchial epithelial cells, we demonstrate that cigarette smoke extract (CSE) sequentially activated NADPH oxidase; increased intracellular levels of ROS; activated AMPK, mitogen-activated protein kinases (MAPKs), nuclear factor-κB (NF-κB), and signal transducer and activator of transcription proteins 3 (STAT3); and induced interleukin-8 (IL-8). Additionally, using a ROS scavenger, a siRNA that targets AMPK, and various pharmacological inhibitors, we identified the signaling cascade that leads to induction of IL-8 by CSE. All these CSE-induced events were inhibited by glucosamine pretreatment. Our findings suggest a novel role for glucosamine in alleviating the oxidative stress and lung inflammation induced by chronic CS exposure in vivo and in suppressing the CSE-induced IL-8 in vitro by inhibiting both the ROS-sensitive NADPH oxidase/AMPK/MAPK signaling pathway and the downstream transcriptional factors NF-κB and STAT3.

Glucosamine hydrochloride exerts a protective effect against unilateral ureteral obstruction-induced renal fibrosis by attenuating TGF-β signaling

Abstract

Renal fibrosis is a common consequence of unilateral ureteral obstruction, which provides a useful model to investigate the pathogenesis of obstructive nephropathy and progressive renal fibrosis. Transforming growth factor (TGF-β1) has been recognized as a key mediator in renal fibrosis by stimulating matrix-producing fibrogenic cells and promoting extracellular matrix deposition. Therefore, considerable efforts have been made to regulate TGF-β signaling for antifibrotic therapy. Here, we investigated the mode of action of glucosamine hydrochloride (GS-HCl) on TGF-β1-induced renal fibrosis. In the obstructed kidneys and TGF-β1-treated renal cells, GS-HCl significantly decreased renal expression of α-smooth muscle actin, collagen I, and fibronectin. By investigating the inhibitory mechanism of GS-HCl on renal fibrosis, we found that GS-HCl suppressed TGF-β signaling by inhibiting N-linked glycosylation of the type II TGF-β receptor (TβRII), leading to an inefficient trafficking of TβRII to the membrane surface. Defective N-glycosylation of TβRII further suppressed the TGF-β1-binding to TβRII, thereby decreasing TGF-β signaling. Notably, GS-HCl treatment significantly reduced TGF-β1-induced up-regulation of Smad2/3 phosphorylation and transcriptional activity in vivo and in vitro. Taken together, GS-HCl-mediated regulation of TGF-β signaling exerted an antifibrotic effect, thereby ameliorating renal fibrosis. Our study suggests that GS-HCl would be a promising agent for therapeutic intervention for preventing TGF-β1-induced renal fibrosis in kidney diseases.

Key message

Glucosamine-mediated attenuation of TGF-β signaling ameliorates renal fibrosis in vivo

TGF-β1-induced fibrogenic action is reduced by glucosamine in vitro

N-glycosylation of the type II TGF-β receptor is suppressed by glucosamine

Glucosamine-induced defective N-glycosylation of TβRII decreases TGF-β signaling.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-013-1086-1) contains supplementary material, which is available to authorized users.

Glucosamine induces activated T cell apoptosis through reduced T cell receptor

Glucosamine (GlcN), like N-acetylglucosamine (GlcNAc), is salvaged into the hexosamine pathway and is converted to UDP-GlcNAc. Golgi N-glycan branching enzymes produce N-glycans, using UDP-GlcNAc as a substrate, which attach to the T cell receptor (TCR) and cytotoxic T-lymphocyte antigen-4 (CTLA-4). These findings suggest that GlcN exerts the immunoregulation through TCR signalling, which could be involved not only in cytokine production but also activated T cell apoptosis. In fact, a preliminary study showed that GlcN reduced the number of CD3+ T cells of NC/Nga mice with AD-like skin lesions. Therefore, whether apoptosis of T cells would be one of the potential molecular mechanisms of GlcN-induced immunosuppression was investigated. Cultured human primary along with Jurkat T cells and purified T cells from NC/Nga mice with or without Df-induced AD-like skin lesion were used for the study. Glucosamine treatment increased the number of T cells expressing β1,6GlcNAc-branched N-glycans, with reduced ZAP-70 phosphorylation and enhanced CTLA-4 expression. Glucosamine treatment reduced the number of activated T cells from both the human primary and Jurkat cells and the dermatitis-induced mice. The expression of FasL and activated caspases, particularly caspase-3, was increased, whereas the phosphorylation of PI3K, Akt and NF-κB was decreased by GlcN treatment. Therefore, in addition to down-regulating TCR signalling and promoting CTLA-4 expression, GlcN may also suppress T cell function by enhancing apoptosis of activated T cells, through both extrinsic and intrinsic apoptotic signalling pathways, which were regulated by the inhibition of PI3K/Akt and NF-κB phosphorylation.

The effect of glucosamine sulfate on the proliferative potential and glycosaminoglycan synthesis of nucleus pulposus intervertebral disc cells

STUDY DESIGN

On the basis of the similarities in the structure of cartilage and intervertebral disc and on the property of glucosamine of being the building block for the construction of proteoglycan aggregates, we investigated the compound's role in the proliferation of nucleus pulposus cells under iso- and hyperosmotic conditions, the putative activation of signaling cascades, and the induction of glycosaminoglycan production.

OBJECTIVE

We examined the mode of action of glucosamine in nucleus pulposus cells.

SUMMARY OF BACKGROUND DATA

Glucosamine that naturally occurs in cartilage tissues has been widely used for treating osteoarthritis, but its role in nucleus pulposus cells is largely unknown.

METHODS

The effect of glucosamine sulfate on the viability and proliferation of nucleus pulposus cells was assessed by the microculture tetrazolium test (MTT) assay, direct cell counting, and tritiated thymidine incorporation. Changes in the expression and phosphorylation profile of selected proteins were estimated by Western analysis. Glycosaminoglycan production was measured using the Blyscan assay.

RESULTS

We showed that glucosamine sulfate up to 1 mM did not influence the viability, proliferation rate, or novel DNA synthesis of nucleus pulposus cells in the presence or absence of elevated osmolality but induced the transient phosphorylation of p38 mitogen-activated protein kinase. The highest concentration used (10 mM) negatively affected cellular proliferation and resulted in deactivation of extracellular signal-regulated kinases and c-Jun N-terminal kinases. Interestingly, these effects resulted from an additional hyperosmotic stress provoked by glucosamine alone. Finally, we found that a long-term incubation with glucosamine leads to an increase in the glycosaminoglycan content of nucleus pulposus cells.

CONCLUSION

Glucosamine sulfate was not found to reverse the high osmolality-mediated delay of proliferation in nucleus pulposus cells needed for the maintenance of the tissue's homeostasis. In addition, glycosaminoglycan synthesis stimulated by glucosamine provides a possible promising clinical role for treating disc degenerative disorders.

Lipopolysaccharide enhances mouse lung tumorigenesis: a model for inflammation-driven lung cancer

The association between pulmonary inflammation and lung cancer is well established. However, currently there are no appropriate models that recapitulate inflammation-related lung cancer in humans. In the present study, we examined, in 2 tumor bioassays, enhancement by bacterial lipopolysaccharide (LPS) of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice. Mice that were treated with NNK alone developed 29.6 ± 9.8 and 36.2 ± 4.1 lung tumors per mouse in experiments 1 and 2, respectively. Chronic intranasal instillation of LPS to NNK-treated mice increased the multiplicity of lung tumors to 47.3 ± 16.1 and 51.2 ± 4.8 lung tumors per mouse in experiments 1 and 2, corresponding to a significant increase by 60% and 41%, respectively. Moreover, administration of LPS to NNK-pretreated mice significantly increased the multiplicity of larger tumors and histopathologically more advanced lesions (adenoma with dysplasia and adenocarcinoma), macrophage recruitment to the peritumoral area, and expression of inflammation-, cell proliferation-, and survival-related proteins. Overall, our findings demonstrated the promise of the NNK-LPS-A/J mice model to better understand inflammation-driven lung cancer, dissect the molecular pathways involved, and identify more effective preventive and therapeutic agents against lung cancer.